MRCOPHTH Flashcards
(160 cards)
1
Q
Acute zonal occult outer retinopathy (AZOOR)
A
- an idiopathic conditions which may be precipitated by punctate inner choroiodapthy (PIC), multifocal choroiditis (MIC) or multiple evasnescent white dot syndrome (MEWDS)
- it is characterized by a rapid loss of visual field which cannot be explained by the ophthalmoscopic changes
- majority of the sufferers are healthy young white myopic females.
- initial presentation is with photopsia and increased blind spot in the presence of normal visual acuity. Later, the visual field is decreased with decreased visual acuity.
- fluorescein angiography is not helpful as it is normal or might only show the precipitation condition initially.
- In electrophysiology, the electro-oculogram (EOG) light rise is often reduced and the ERG is usually very abnormal.
- there is no effective treatment. In some patients, the vision returns spontaneously.
2
Q
Idiopathic polypoidal choroidal vasculopathy (IPCV)
A
- is also known as posterior uveal bleeding syndrome and multiple recurrent serosanguineous REP detachment syndrome.
- although originally described in black hypertensive females in middle age. It is now been recognized in other races.
- the characteristic lesion appears to be an inner choroidal vascular network of vessels ending in an aneurysmal bulge or outward projection.
- recurrent and multiple REP detachments with or without the associated subretinal bleeding (posterior uveal bleeding syndrome) may then occur.
- the absence of drusen, retinal vascular disease and intraocular inflammation is characteristic of the condition. Vitreous haemorrhage may also occur.
- the lesions were originally described to be peripapillary in location, but pure macular lesions have also been reported.
- indocyanine green angiography is most helpful in identifying polyps.
- it has a better prognosis than other causes of haemorrhagic detachments of the retina. Direct laser therapy to the lesion appears to carry a better prognosis in IPCV compared to laser therapy of CNV in AMD patients.
3
Q
Stickler’s syndrome
A
- autosomal disorders
- associated with abnormal production of type II collagen
- ocular features include myopia, cataracts, strabismus, and optically-empty vitreous traction and lattice degeneration
- multiple retinal breaks occurs in more than 75% of the patients.
- systemic manifestation include maxillary and mandibular hypoplasia, cleft palate, abnormal uvula, neurosensory hearing loss and skeletal abnormalities with joint hyperextensibility, and marfanoid habitus
4
Q
Difference between ARN and PORN
A
- both conditions are associated with herpes virus chiefly herpes simplex and zoster
- both conditions can lead to retinal detachment
- ARN is seen both in healthy and immunocompromised patients whereas PORN is seen exclusively in AIDS or immunocompromised patients
- vitritis is often severe in ARN but is usually minimal or absent in PORN
- ARN responds to intravenous acyclovir but PORN responds poorly and PORN patients usually have poorer eventual visual outcome
5
Q
Vigabatrin
A
- indicated only when all other appropriate antiepileptic drug combinations have proved ineffective or poorly tolerated
- is an GABA transaminase inhibitor
- indicated as first line therapy only in infantile spasm
- about 1/3 of epilepsy patients using it have characteristic visual field defects which can vary from asymptomatic to severe and disabling
- the defect is not reversible even with cessation of the therapy
- the cause of the visual field loss is unknown
- not recommended in patients with pre-existing visual field defects
6
Q
Familial exudative vitreoretinopathy
A
- FEVR is normally an autosomal dominantly inherited disease but X-linked inheritance has been described.
- although both eyes are affected, the degree of involvement may be very asymmetrical.
- the fundus appearances may be confused with retinopathy of prematurity (ROP)
- it is characterized by peripheral areas of avascularity in the peripheral retina, almost indistinguishable from ROP. The lack of history of premature birth, low birth weight, or oxygen therapy differentiates this condition from retinopathy of prematurity.
- dragging of the retina temporally with vessel straightening, subretinal exudation, cicatrization and retinal detachment are all features of this condition. Complications include neovascularisation in the peripheral retina.
- treatment with cryotherapy to neovascular areas, and scleral buckling and vitrectomy procedures for tractional detachments have all been used in the treatment.
- relentless progression is uncommon. Visual impairment tends to occur early and it is rare to lose vision after the age of 30 unless the patient develops tractional retinal detachment.
7
Q
Oguchi disease
A
- is a form of congenital stationary night blindness
- is characterized by a golden/grey-white discoloration of the retina giving a metallic sheen to the back of the eye. This disappeared when the fundus was viewed after some time in the dark and has become known as the Mizuo-Nakamura phenomenon.
- visual acuity, colour vision and visual fields are usually normal in Oguchi disease.
- two genes involved in Oguchi disease have been identified and include: arrestin, a gene located in the region of the distal arm of chromosome 2q, and rhodopsin kinase. The arrestin mutations are more common in Japanese Oguchi disease, and rhodopsin kinase in European Oguchi disease.
- patients are asymptomatic in light, but are night blind.
- dark adaptation shows extremely retarded rod function.
8
Q
Retinal crystals are seen in
A
- drug-induced:
- tamoxifen
- canthaxanthin
- talc
- methoxyflurane
- metabolic disorders
- cysintonosis
- primary oxalosis type 1
- Others
- Bietti retinal dystrophy
- Sjorgren-Larsson syndrome
9
Q
Shaken baby syndrome
A
- typically occurs in children less than 3 years of age and results from violent shaking
- there is no external eye injury but the posterior segment shows retinal haemorrhages (both intra and subretinal) and vitreous haemorrhage
- skull fracture is uncommon but CT scan reveals subarachnoid or intracerebral haemorrhages
- vomiting, lethargy and focal neurologic findings are common
- the visual prognosis is poor due to macular scarring, vitreous haemorrhage and retinal detachment
10
Q
In central retinal artery occlusion and ophthalmic artery occlusion
A
- both give cherry-red spot in the acute phase
- both causes relative afferent pupillary defect
- in ophthalmic artery occlusion, the a and b waves on the ERG are abnormal due to insult to the outer and inner retina
- in ophthalmic artery occlusion, both the choroidal and retinal circulation are delayed
- in ophthalmic artery occlusion, the REP is disturbed resulting in pigmentary changes at a later date
11
Q
Aberrant regeneration of the third nerve (oculomotor synkinesis):
A
- features of congenital third nerve palsies and those caused by tumours, aneurysms and trauma but not those due to ischaemic ophthalmoplegia
- known features include: elevation of the upper lid on attempted adduction or depression of the eye, retraction of the globe on attempted depression or elevation of the eye
- constriction of the pupil on attempted adduction or depression
12
Q
Abnormal material in the vitreous include
A
- pseudoexfoliation in pseudoexfoliation syndrome
- haemosiderin from vitreous haemorrhage
- amyloidosis in familial amyloidosis
- calcium in asteroid hyalosis
13
Q
Absent of pupil response to direct and consensual light response
A
- occur when the iris of the affected eye is paralysed and this occur in
- blunt trauma
- third nerve palsy
- atropine
- siderosis bulbi
14
Q
Acquired syphilis
A
- causes painless ulcer in the primary stage which is highly infectious
- in the secondary stage, the patient may develop a rash which is non-infectious
- uveitis can occur in the secondary stage
- treatment is with penicillin
- Interstitial keratitis is a feature of congenital syphilis
15
Q
Acute posterior multifocal placoid pigment epitheliopathy (APMPPE)
A
- typically affects healthy young adults who presents with sudden onset central or paracentral visual loss after a flu like illness
- scattered, patchy creamy lesions at the level of the retinal pigment epithelium layers
- the lesions fade after one to two weeks leaving behind granular pigmentary changes
- fluorescein angiography shows early blockage of choroidal circulation by these lesions but in the late phase the lesions show late staining
- other findings: uveitis, serous retinal detachment, cerebral vasculitis, cerebrospinal fluid pleocytosis, headache, hearing loss and tinnitus
- spontaneous resolution is common and systemic steroid has not been shown to be useful
16
Q
Adenocystic carcinoma of the lacrimal gland:
A
- the most common malignant tumour of the lacrimal gland
- has no well-defined capsule
- invade perineural tissue causing pain and metastasise early to the brain
- 5 histologic patterns: cribriform (Swiss cheese and of lower grade), solid (basaloid), sclerosing, comedocarcinomatous and tubular (ductal)
- treatment is with orbital exenternation and removal of involved bone
- the prognosis is very poor
17
Q
Albinism
A
- can be of oculocutaneous or ocular types
- oculocutaneous types can be divided into tyrosinase-positive and tyrosinase-negative types. Hair bulb test is useful to differentiate the two within the first three years of life
- is associated with abnormal platelet aggregation in Hermansky-Pudlak syndrome
- poor vision is usually due to macular hypoplasia
18
Q
Angioid streaks occur in many conditions including:
A
- pseudoxanthoma elasticum
- Ehlers-Danlos syndrome
- sickle cell disease
- Paget’s disease
19
Q
Ankylosing spondylitis:
A
- inflammatory disorders of spinal joints
- 90% have the HLA-B27 halotype
- systemic features include peripheral arthritis, uveitis, aortic valve incompetence and chronic inflammatory bowel disease
- the condition is commoner and more severe in males than females
- in the spine, the inflammation begins at the site where ligaments are attached to vertebral bone (the entheses), however, signs may occur before the patients complain of any symptoms.
20
Q
Anterior capsule removal:
A
capsulorrhexis is a more difficult technique to master than capsulotomy but produces a stronger edge and causes less displacement of the lens due to more equal distribution of force should the capsule undergoes fibrosis
21
Q
Anti-glaucoma medications
A
- beta-blocker causes slowing of heart rate but is not contra-indicated in primary heart block ( prolonged PR interval)
- beta-blocker should be avoided in patients taking centrally acting calcium channel blocker such as verapamil. Nifedipine acts peripherally
- acetazolide contains structure similar to sulphonamide and should be avoided in those who is allergic to it
- acetazolamide causes diuresis and loss of potassium, supplement may be needed latanoprost is contraindicated in patients with intraocular inflammation
*
22
Q
Benign intracranial hypertension:
A
- the eye movement is usually normal but there may be sixth nerve palsy
- the CT scan should be normal
- in young women on contraceptive pill, brain scan is important to exclude saggital sinus thrombosis which may presents with similar pictures
- optic nerve fenestration is indicated if there were evidence of optic nerve dysfunction
- the condition can be treated with diuretic and repeated lumbar puncture. Ventricular-peritoneal is rarely required.
23
Q
Biopsy report in rheumatoid arthritis include
A
- posterior scleritis
- episcleral necrotic tissue
- vasculitis
24
Q
Breaks in Descemet’s membrane occurs in
A
- trauma as in forcep delivery
- keratoconus
- congenital glaucoma
25
Central retinal artery occlusion:
* rubeosis iridis occurs in about 10% of patients
* rarely retinal neovascularization is seen
* atrial fibrillation is a cause of embolus which may lead to retinal artery occlusion
* delayed hyperfluorescence of choroidal circulation is a feature of ophthalmic artery occlusion
* optic atrophy occurs due to loss of ganglion cell layers and these may take months to develop
26
Central serous retinopathy
* the patient usually presents with distorted vision without significant central visual loss
* Amsler's chart testing usually shows distortion of lines or scotoma
* the image appears smaller than the unaffected eye
27
Choroideremia
* X-linked recessive disorder characterised by progressive degeneration of the choriocapillaris and RPE
* typically affects male
* onset is in the first decade with night blindness
* central vision is affected late
* ERG shows reduced a and b waves female carriers may shows peripheral pigmentary changes
28
Coat's disease
* non-hereditary, unilateral congenital disorder characterised by abnormal telangiectatic and aneurysmal retinal vessels in the peripheral retina
* male outnumber female by 3 to 1
* presents with leukocoria and strabismus. Untreated can lead to exudative retinal detachment, glaucoma and pthisical eye
* laser is useful in destroying the abnormal blood vessels
29
Colour defect:
* macular problems usually cause loss of blue/yellow colour discrimination
* optic nerve defects tend to result in red / green colour defect
30
Congenital glaucoma secondary to:
* aniridia
* Sturge-Weber's syndrome
* anterior chamber angle cleavage syndrome such as Peter's anomaly or Axenfeld's syndrome
31
Corneal dystrophy:
- inherited and bilateral conditions
- the following abnormal substance are documented:
* glycoaminoglycan (macular dystrophy, fleck dystrophy)
* hyaline degeneration (granular dystrophy)
* amyloid (lattice dystrophy)
* lipid (fleck dystrophy)
* cholesterol (central crystalline dystrophy)
32
Cyclosporin A
* is the product of the fungus Tolypocladium inflatum
* inhibits T cell activation by stopping the expression of receptors on T lymphocytes that recognize the DR antigen found on antigen presenting cells
* has poor tissue penetration when applied topically
* is the drug of choice in patients with Behcet's disease
* causes nephrotoxicity as the main side effect which is dose-dependent
* other side effects include: hypertension, hypertrichosis, gastrointestinal upset, gingival hyperplasia, anaemia and raised ESR
33
Deafness occurs in
* Cockayne's syndrome: premature ageing, dwarfism, bird like facies and retinal degeneration
* Altroem's syndrome: retinitis pigmentosa, deafness, obesity and diabetes mellitus
* Alport's syndrome: haematuria, sensorineural deafness, anterioir lenticonus
* Usher's syndrome: neurosensory deafness, retinitis pigmentosa
34
Dendritic ulcer of the cornea can be treated with:
* iodination
* debridement
* topical or systemic acyclovir
35
Dissociated vertical deviation
* refers to the phenomenon in which the eye elevates when the amount of light entering it is reduced
* usually begins between 2 to 3 years of age
* associated with infantile esotropia
* the binocular vision is usually poor
* surgery of choice is either superior rectus recession or Faden's procedure
36
Duane type A
Brown's classification
Type A: limited abduction and less marked adduction limitation
Type B: limited abduction and normal adduction
Type C: limitation of adduction exceeds the limitation of abduction
* widening of the palpebral fissure on abduction
* globe retraction and palpebral narrowing on adduction
* face turns to the affected side is common
* caused by innervation of the lateral rectus by a branch of third nerve in place of absent sixth nerve
* sixth nerve nucleus aplasia has been documented
37
Enlarged corneal nerves occur in
* multiple endocrine adenomatosis
* keratoconus
* ichthyosis
* Refsum's disease
* Fuchs' corneal dystrophy
* neurofibromatosis
* leprosy
* trauma
* congenital glaucoma
* failed corneal graft
* keratoconjunctivitis sicca
* advanced age
* acanthamoeba keratitis
*
38
Giant cell arteritis
* disease of the elderly
* sudden, painless and profound visual loss
* female more susceptible than male
* headache, low grade fever, anorexia, weight loss, tenderness upon brushing hair and jaw claudication
* ESR and C-reactive proteins are always raised but not diagnostic of the condition
* diagnosis is base on biopsy which reveal fragmentation of the internal elastic lamina and giant cell infiltration of the tunica media of the artery. However, giant cells are not essential for diagnosis.
39
Goldenhar's syndrome:
* is a type of hemifacial microsomia
* sporadic occurrence
* facial asymmetry with mandibular hypoplasia
* preauricular appendages, malformation of the ear, hearing loss caused by external ear lesions
* ocular features: epibulbar dermoids, limbal dermoids, eyelid colobomas and subcutaneous dermoids of the lids
40
Heimann-Bielschowsky phenomenon
a type of monocular nystagmus that occurs due to longstanding poor vision in one eye with amblyopia, optic neuropathy, or dense cataract
41
Heterochromic cyclitis
* chronic uveitis associated with cataract and glaucoma
* glaucoma develops in 20% of patients
* iris atrophy causes transillumination
* Amsler's sign occurs during cataract extraction and is due to wispy iris vessels which extends from the iris to the trabecular meshwork and do not cause anterior synechiae
* is resistant to steroid treatment
42
Histological staining:
* Giemsa stain can demonstrate inclusion body such as chlamydia
* osmium tetroxide is used to fix and stain myelin for electron microscopy
* yeast and fungi can be stained with Fuelgin's stain, PAS, Luxol blue fast and Gomori methenamine silver
* eosin stains the cytoplasm pink whereas haematoxylin stains the nuclei blue
43
Holme-Adie's pupil
* there is light-near dissociation however there may be delayed or absent pupil reaction to both
* the condition is usually unilateral
* women are affected more often than men
* due to paralysis of the ciliary muscle, the accommodation is impaired
* denervation hypersensitivity is demonstrated by constriction to 2.5% methacholine and 0.1% pilocarpine
44
Hypotony:
* occurs when the intraocular pressure is sufficient low to compromise the ocular function usually below 6 mmHg
* may be caused by decreased aqueous production or excessive aqueous drainage
* can results in:
- corneal oedema
- cataract formation
- uveal effusion
- macular oedema
- disc oedema
- choroidal folds
- choroidal detachment
45
Hypoxic damage in diabetic mellitus is suggested by
* cotton-wool spots
* extensive IRMA
* vascular bleading
* extensive retinal haemorrhages
* iris neovascularization
46
In blow-out fracture
* the orbital rim may be fracture or intact. In the former a step can be felt
* occur only when the air sinuses have develop
* surgical emphysema is a feature
* although typically cause problem with upgaze, the horizontal recti have connective tissue that extends to the orbital floor and therefore horizontal movement may be impaired to some extent
* the infraorbital nerve is involved but the nerve does not supply the tip of the nose which is by nasociliary nerve
47
In corneal graft:
* the epithlium, keratocytes, nerves and epithelium will eventually be replaced by the host tissue
* the endothelium does not regenerate and therefore will remains that of donor.
* the descemet's membrane is produced by the endothelium and will therefore remains that of donor
48
Indications for subretinal fluid drainage include:
* bullous detachment making hole or tear identification difficult
* immobilized retina
* raised intraocular pressure
* inferior retinal detachment
49
Inferior oblique recession:
* a weakening procedure
* is performed in the following situation: primary inferior oblique overaction as in V-pattern esotropia or secondary inferior overaction as in ipsilateral superior oblique palsy or contralateral superior rectus palsy
* is more difficult to perform than myectomy as the muscle needs to be reattached posteriorly
50
Intravitreal gas injection:
* can cause retinal tear and cataract
* C3F8 has a longer half life than SF6 and also more expansile. C3F8 typically expands to 4 times its volume where as SF6 only 2 to 3 times and therefore C3F8 also causes more significant increase in intraocular pressure than SF6
51
Investigation of sarcoidosis
* chest X-ray typically shows bilateral hilar lymphadenopathy, there may also be interstitial infiltrate
* ACE concentration is increased
* conjunctival biopsy may show non-caseating granuloma
* serum calcium may be raised in sarcoidosis
* gallium scan shows increase in parts of body affected by sarcoidosis
52
Kayser-Fleishcer's ring
* occurs in Wilson's disease and intraocular copper foreign body
* the ring is caused by copper deposited in Descemet's membrane which may be orange, brown, green- brown or grey in colour
* it begins superiorly then inferiorly and finally circumferentially
* regresses with D-penicillamine treatment
53
Keratoconus occurs in
* connective tissue disorders such as Ehlers-Danlos's syndrome and Marfan's syndrome
* atopic eye conditions such as atopic keratoconjunctivitis
* Down's syndrome
54
Laser:
* green light is not absorbed by xanthophyll and therefore it is theoretically more advantageous to use green laser in the macular area
* diode laser penetrate vitreous haemorrhage well and is therefore ideal in vitreous haemorrhage
* YAG laser is colourless and therefore require neodymium to give it red colour for targeting
* used in ophthalmic practice is classified as type IV laser
55
Leber's optic neuropathy
* a mitochondrial inherited disease
* bilateral loss of central vision which is severe and painless
* typically in the second decade of life
* classic early picture shows a triad of circumpapillary telangiectatic microangiopathy, pseudoedema of the disc and absent fluorescein staining
56
Many drugs have been implicated in optic neuropathy, the following are the better known:
* anti-tuberculous: ethambutol and isoniazid
* chloramphenicol
* digitalis
* oral hypoglycaemic agents: chlopropamide and tolbutamide
* chloroquine
* disulfirum
* D-penicillamine
57
Marfan's syndrome:
* autosomal dominant condition
* caused by incorrect expression of a gene product for 350kD glycoprotein known as fibrillin which is responsible for the extracellular microfibrol network. Type I collagen abnormality is seen in osteogenesis imperfecta
* 80% have lens subluxation which is typically displaced up and out
* lenticular myopia with normal axial length is a feature
* unlike homocystinuria, the patient is mentally normal
58
Measles:
* is a paramyxovirus containing RNA
* causes Koplik's spots on the conjunctiva and caruncle
* causes acute catarrhal conjunctivitis
* causes punctate keratitis which is self-limiting in developed countries but in the presence of malnutrition especially vitamin A deficiency, blinding keratitis can occur
* subacute sclerosing panencephalitis tends to occur in children who acquire measles before one year of age. It is characterized by progressive neurological deficit with dementia, myoclonus and focal signs causing death.
59
Melanocytoma
* benign, highly pigmented tumour arising from melanocytes
* most commonly found in optic nerve head
* histologically shows plump polyhedral cells
* equally sex incidence
* commoner in black population
* usually asymptomatic but may show enlargement of blind spots
* 50% have associated choroidal naevus
* rarely the tumour shows necrosis, vascular obstruction and optic nerve compression
60
Mesodermal dysgenesis:
* Axenfeld's syndrome is associated with posterior embryotoxon and iris strands extending onto the cornea. Iris hypoplasia is a feature of Reiger's anomaly
* Axenfeld's syndrome is an autosomal dominant disorder
* Rieger's anomaly is associated with posterior embryotoxon, prominent iris processes and iris stroma atrophy. Rieger's syndrome is Rieger anomaly plus skeletal, facial, cranial and dental anomalies
* Peter's anomaly consists of bilateral central corneal opacity due to defects in the posterior stroma. 50% of cases have glaucoma
61
Microangiopathy in diabetes mellitus is characterised by
* microvascular obstruction and non-perfusion of capilaries
* retinal capillary microaneurysms
* absent membrane thickening
* loss of pericytes
* intraretinal microvascular abnormality
62
Mutton fat keratic precipitates occurs in chronic granulomatous uveitis and seen in
* tuberculosis
* fungal
* leprosy
* syphilis
* sarcoidosis
* juvenile xanthogranuloma
* histiocytosis X
* sympathetic ophthalmia
* Vogt-Koyanagi-Harada syndrome
* toxoplasmosis
*
63
Nystagmus
* see-saw nystagmus is seen with bitemporal hemianopia
* down-beat nystagmus occurs with lesion in the cervico-medullary junction at the foramen magnum
* manifest latent nystagmus is a type of horizontal jerk nystagmus which increases in amplitude when one eye is covered. It occurs in strabismus, amblyopia or uniocular pathology such as cataract
* gaze-evoked potential is not specific for cerebellar lesion, it occurs when the eyes are unable to maintain an eccentric gaze position through weakness of muscle tone in the agonist muscle
* convergence retraction nystagmus occurs with mid-brain tumours such as pinealoma
64
Ocular bobbing
* conjugate involuntary recurrent downward movement of the eyes
* rapid downward movement with a slower return to the neutral position
* absent horizontal movements
* occurs in patients with acute pontine lesion who are either comatose or locked-in state
* can occur with tumour in the pontine
65
Optic nerve glioma
* associated with type I neurofibromatosis
* most common type is pilocytic (hair-like) astrocytoma
* the age of onset is usually before the age of 10
* low-grade and rarely infiltrate the perineural tissue
* reactive meningeal hyperplasia
* good long-term survival
*
66
Pars planitis
* commonly affect young adult and children
* presents with floater or decreased visual acuity due to cystoid macular oedema
* 80% bilateral
* clinical examination shows inflammatory cells and snowball opacity in vitreous
* main complications are cataract and cystoid macular oedema. However, the visual prognosis is usually good
* rare complication include band keratopathy, glaucoma, vitreous organisation, tractional retinal detachment and vitreous haemorrhage.
* treatment is indicated only with decreased visual acuity from CMO and severe inflammation
* treatment include: periocular steroid, cryotherapy to vitreous base, par plana vitrectomy and use of immunosuppresive agents.
*
67
Pathology of thyroid ophthalmopathy
* there is enlargement and inflammation of orbital tissue especially the extraocular muscles
* histologically there is interstitial oedema and inflammatory cell infiltration (mainly lymphocytes, plasma cells and sometimes mast cells)
* thecondition tend to involve the nontendinous part of extraocular muscle
* the endomysial fibroblasts produces mucopolysaccharide especially hyaluronic acid
* the muscles are initially inflammed and at later stage undergoes fibrosis and shows fatty infiltrate
*
68
Persistent hyperplastic primary vitreous
* caused by abnormal regression of primitive hyaloid vascular system
* typically there is a fibrovascular stalk extending from optic disc and form a retrolental membrane
* the membrane extend to the ciliary process and if contract can lead to elongation of the ciliary processes
* causes shallow anterior chamber and acute glaucoma in untreated cases
* the prognosis is good if treated early especially if the retina were normal
69
Phlyctenular conjunctivitis:
* is a type IV immune response to some sensitized antigen typically bacteria antigen
* tuberculosis is a known cause but it is more often associated with Staphlococcus aureus
* often occurs near the limbus
* commoner in children
* topical steroid is the treatment of choice
70
Phospholine iodide:
* is an acetylcholinesterase inhibitor which is used as a miotic agent
* can help patient with hypermetropic accommodative esotropia and patient with a high AC/A ratio
* causes contraction of ciliary muscle and iris sphincter resulting in an increased accommodation for a given accommodative effort and therefore less convergence
* side effects include: iris cysts (reduced with concurrent treatment with phenylephrine), cataract, retinal detachment and angle closure glaucoma in adults.
* has systemic effect and can prolong the action of succinylcholine. Therefore, patients should not have succinylcholine or have to stop the drops at least six weeks prior to surgery
71
Pseudoexfoliation syndrome:
* compare with primary open angle glaucoma, the intraocular pressure is more difficult to control with medication and there is greater incidence of asymmetry of glaucoma. Otherwise, the age range is identical and the success rate of trabeculectomy is not different
* there is presence of pigments in the trabecular meshwork called the Sampaolesi's line
72
Reduced blinking occurs in
* Parkinson's disease
* progressive supranuclear palsy
* alcohol intoxication
* neurotrophic keratitis
* contact lens wear
73
Reduction of post-operative astigmatism:
* reduced by small incision
* reduced by incision far from the centre of the cornea and therefore limbal better than corneal approach and temporal corneal approach better than superior approach (the horizontal diameter of the cornea is greater than the vertical diameter)
74
Refractive surgery:
* radial keratomy is suitable only for myopes with less than 8D of myopia. Long term stability is a problem in between 15 to 30% of patients with hypermetropic shift and there are complications associated with the procedures including loss of best corrected visual acuity, glare, diurnal fluctuation of visual acuity and etc.
* removal of suture along the axis of the largest plus cylinder is useful in reducing astigmatism
* keratomileusis involves removal of the anterior part of the corneal tissue which is then carved on its posterior stromal surface to alter its radius of curvature before replacing it.
*
75
Retinal dialysis
* caused by full thickness separation of the retina at the ora serrata
* traumatic dialysis is most often found in the superonasal quadrant
* idiopathic dialysis is most often in the inferotemporal quadrant
* can be closed with cryotherapy to the base of the dialysis followed by local scleral buckle
76
Retinoblastoma
* most cases are due to new gene mutation only 10% is inherited
* caused by deletion of 13q14
* rosettese suggests cell differentiation and therefore better prognosis; however other factors such as size and optic nerve involvement may be more important
* has increased risk of osteosarcom (the oncogene of which is also located on chromosome 13)
* prognosis is generally good at around 90%
77
Retinoschisis
* presents in 5% of the population and is caused by the splitting of the neurosensory retinal in the outer plexiform layer
* often bilateral
* arises from coalescence of peripheral cystoid degeneration
* associated with hypermetropia
* asymptomatic but can cause absolute scotoma (cf with retinal detachment which causes relative scotoma)
* does not cause water mark which is a feature of retinal detachment and is due to transformation of escaped retinal pigment epithelial cells
* renal breaks on the internal layer is common but if associated with breaks in the outer layer, there is a risk of retinal detachment
78
Roth's spots
* many causes including subacute bacterial endocarditis, leukaemia, anaemia etc
* contain white areas in the centre of retinal haemorrhage
* the white areas may contain immunocomplex, lymphoblasts or purulent exudates
* in subacute bacterial endocarditis, the white centres may contain organisms, although the majority are sterile and consists mainly of white blood cells and fibrin thrombus at the site of extravasation of blood
79
Stigma of acute angle closure glaucoma:
* iris atrophy
* sphincter paralysis due to ischaemia
* pigment dispersion
* glaukomflecken which is white opacities on the anterior surface of the lens caused by necrosis of the anterior lens capsule
80
Sympathetic ophthalmitis
* a uncommon bilateral granulomatous panuveitis which occurs after penetrating ocular injury or intraocular surgery
* the inflammation usually begins 4 to 8 weeks after the injury
* Dellen-Fuch's nodules are seen at the level of Bruch's membrane and represent aggregates of epitheloid cells, it is not diagnostic as the nodules also occur in VKH syndrome
* may have systemic manifestation identical to Vogt-Koyanagi-Harada syndrome with cerebrospinal fluid pleocytosis, miningismus, alopecia, vitiligo and poliosis
* prevention is only useful if the injured eye were removed within the first 2 weeks after injury
81
The classification of retinopathy of prematurity is as follow:
* Stage 1: presence of demarcation line
* Stage 2: presence of demarcation line that protrudes into the vitreous
* Stage 3: presence of peripheral retina fibrovascular proliferation
* Stage 4: subtotal retinal detachment
* Stage 5: total retinal detachment
82
The following association are true
* abetalipoproteinaemia with acanthocytosis
* Refsum's disease with cerebellar ataxia
* Friedrich'a ataxia with spinocerebellar degeneration
* Paget's disease and deafness
* Homocystinuria causes recurrent aterial thrombosis
83
The following conditions are inherited as
* X-linked in protanopia (red-green colour blindness) and juvenile retinoschisis
* autosomal dominant in neurofibromatosis
* autosomal recessive in blue cone achromatopsia
* non-inherited in Sturge-Weber's syndrome
84
The following conditions are pre-malignant
* actinic keratosis is the result of metaplasia due to ultraviolet light
* Bowen's disease
Oncocytoma of the caruncle results from metaplasia of the accessory gland and is not thought to be pre-malignant
Squamous papilloma is benign hyperplasia of the skin
Syringoma is benign tumour of the sweat glands
85
The prognosis of retinoblastma is detemined by
* evidence of external spread such as optic nerve involvement
* size of the tumours
* cell differentiation
* Calcification and necrosis are common in retinoblastoma.
86
Thiamine (B1) deficiency
* common in chronic alcoholics and in those with long-standing diseases of the upper gastrointestinal tract such as peptic ulcer or gastric carcinoma
* causes Wernicke's encepholopathy with memory impairment, ataxia, peripheral neuropathy. Ocular signs include external ophthalmoplegia and nystagmus
* there is characteristic perivascular haemorrhages in the region of the fourth ventricle and aqueduct and also in the mamillary bodies
* treatment of choice is with intravenous thiamine (vitamin B1)
87
Unilateral internuclear ophthalmoplegia:
* results from a lesion in the medial longitudinal fasciculus between the sixth nerve and third nerve nuclei
* causes failure of the ipsilateral medial rectus to adduct on horizontal gaze
* there is nystagmus of the contralateral abducting eye (caused by excessive innervation to the normal lateral rectus in accordance with Hering's law)
* diplopia is a feature
* due to abnormal saccade the OKN is abnormal
88
Unrecovered sixth nerve palsy:
* botulinum toxin injection reduces the problem of medial rectus contracture but does not speed up recovery
* resection/recession of the affected eye can move the eye into the primary position and reduces diplopia in this position
* operation on more than two muscles is associated with anterior segment ischaemia
* Faden's procedure on the contralateral medial rectus produces progressive weakening on adduction which matches the poor abduction of the affected eye
89
Uveal melanoma:
* occur mainly in the white population
* the incidence shows little difference between the sexes
* unlike retinoblastoma the optic nerves are seldom infiltrated
* epithelioid cell type is associated with poor prognosis
* blood test is more sensitive than CT scanning in revealing hepatic metastasis
90
Vernal keratoconjunctivitis
* affects mainly young people
* an allergic inflammatory condition characterised by giant papillae in the tarsal conjunctiva
* the limbal type is found commonly in black with typical Horner-Trantas' dots which are giant papillae containing eosinophils
* causes keratitis and corneal ulcer / scarring
* treatment is avoidance of allergens, mast cell stabilisers and short course of steroid in acute phase
91
Xeroderma pigmentosa:
* inheritance is autosomal recessive
* marked sensitive of skin to sunlight
* malignant skin tumours including squamous cell tumour, basal cell carcinoma and fibrosacorma
* main defect is due to the inability of the cells to repair damaged DNA following ultraviolet exposure
92
Carotid-cavernous fistula:
* dilated superior ophthalmic vein can be seen on CT scan due to congestion
* blood in the Schlemmn's canal occurs due to raised episcleral pressure
* as the two cavernous sinuses are interconnected, unilateral fistula can cause contralateral proptosis
* there are two types of fistula: the high flow in which there is direct connection between the internal carotid artery and the cavernous sinus this is seen in the traumatic cases. The low flow is the dural fistula which results from a connection between the meningeal branches of the internal carotid or external carotid artery and the cavernous fistula. The low flow is typically seen in post-menopausal women with history of atherosclerosis or hypertension
* high flow fistula rarely close spontaneously whereas the low flow closes spontaneously in about 50% of cases
93
Cavernous sinus lesion in a patient with unilateral third nerve palsy:
involvement of other nerves in the cavernous sinus such as fourth nerve, sixth nerve, fifth nerve (causing reduced corneal reflex and decreased facial sensation), and sympathetic nerve (pupil constriction).
94
Congenital nystagmus:
* may be sensory due to abnormality involving the afferent vision or motor
* the nystagmus is worse when one eye is covered
* the nystagmus is reduced on convergence and this may result in nystagmus blockage syndrome with esotropia
* about 2/3 of the patients have paradoxical inversion of the opticokinetic response (the direction of the quick recovery phase is the same as that of the drum rotation instead of in the opposite direction)
* oscillopsia is not a feature
* paradoxical pupillary constriction may occur with the pupil initially constrict when the room light is dimmed
95
Lawrence-Moon-Biedle's syndrome have the following features:
* mental retardation
* obesity
* hypogenitalism
* polydactyly
* spastic paraplegia
* retinitis pigmentosa
96
Local anaesthesia:
* peribulbar anaesthesia relies on diffusion of the anaesthetic agents into the muscle cone to achieve anaesthesia whereas with retrobulbar anaesthesia, the anaesthetic agents are injected directly into the muscle cone
* lignocaine works faster than marcaine but the duration of action is shorter
* topical amethocaine can achieve adequate anaesthesia of cornea and conjunctiva but no the iris
* retrobulbar haemorrhage increases the orbital pressure and therefore the risk of expulsive haemorrhage
97
Pigmentry glaucoma:
* typically seen in young myopic males
* raised pressure is believed to be due to blockage of the trabecular meshwork by the pigments
* there is radial iris transillumination
* high intraocular pressure following exercise is a feature
98
Radiation therapy:
* the pathology appears similar to diabetic retinopathy with occlusive microangiopathy secondary to loss of endothelial cell and capillary closure
* the lowest report dose is 11 Gy
* the photoreceptors are more resistant than the vascular cells the damage of which is the main cause of radiation therapy
* patients who are on chemotherapy, hypertensive and diabetic are more vulnerable to radiation therapy
* hyperbaric oxygen is of unproven benefit
99
Sarcoidosis:
* a systemic disorder of unknown origin
* tends to affect people in their 20s and 30s
* produces non-caseating granuloma
* bilateral hilar lymphadenopathies are common even in the absence of chest symptoms
* causes reduced number of circulating lymphocytes
100
Gout:
* is the result of purine metabolism
* may be associated with excess alcohol consumption but not a direct link
* causes conjunctivitis and scleritis if the uric crystals were to become deposited in the conjunctiva or sclera
* may cause uric acid crystals deposition in the cornea typically in the interpalpebral fissure but the crystals are typically subepithelial
101
Laser iridotomy:
* dark colour iris absorbs argon laser well and therefore respond better than light colour iris
* less energy is usually required for YAG than argon laser
* raised intraocular pressure may be reduced with anti-glaucoma treatment such as iodipine
* patient iridotomy is indicated when pigment is seen flowing out of the hole
* cataract may occur but is usually localized and of no visual significant.
102
Latanaprost:
* is a prostaglandin analogue
* more potent than beta-blocker in reducing the intraocular pressure
* works by increasing the uveal scleral outflow
* side effects include: conjunctival injection, increased iris pigmentation, hypertrichosis and ocular inflammation
103
Alport's syndrome:
* a disease with neurosensory hearing loss and haemorrhagic nephritis
* only 15% have ocular abnormalities and this include anterior lenticonus and peripheral retinal fleck
* inheritance may be dominant (most common), X-linked and recessive
104
Argon laser trabeculoplasty:
* high power can lead to significant inflammation and anterior synechiae
* is better in those over 50 years of age
* reduced pressure is due to alternation of the aqueous outflow
* produces a drop of pressure of between 5 to 10 mmHg
* is used when the patient is not responsive to maximal medical therapy for glaucoma
105
Corneal deposits:
* the mucopolysaccharadosis is a group of storage disease caused by an error of carbohydrate metabolism. Corneal deposits are seen in all types except in Sanfilippo's (type III) and the majority of Hunter's (type II) syndrome
* myeloma can lead to amyloidosis of cornea
* cystinosis is an autosomal recessive condition characterized by widespread cystine crystal deposits including the cornea
106
Corneal graft donor:
* history of hepatitis B or HIV are contraindicated
* low endothelial cell count contribute to early corneal decompensation
107
In acute bacterial endophthalmitis:
* Staphylococcus epidermidis is the most common pathogen
* according to the Endophthalmitis Vitrectomy Study, the majority of patients present at 6 days after operation
* the Study also shows systemic antibiotic is of no value and treatment should include intravitreal antibiotics
* the role of steroid is controversial but not contraindicated
* mycotic causes tend to take longer to develop
108
In ptosis surgery:
* brow suspension allows the frontalis to perform upper lids elevation and is therefore recommended in severe congenital ptosis
* Fasavella-Servant is reserved for mild ptosis
* previous ptosis results in distortion of the normal lid anatomy making posterior approach unsuitable
* in mitochondrial myopathy poor Bell's phenomenon is often a feature and maximal resection can result in corneal exposure
* assessment of Bell's phenomenon and corneal sensation are essential prior to surgery to avoid exposure keratitis
109
Infantile esotropia:
* the patients typically present in the first six months of life
* there is a large angle esotropia
* associated features include: inferior oblique overaction (70%), DVD (75%) and latent nystagmus (50%)
* a mild to moderate hypermetropia is common (+2.00 to +3.00 dioptres)
* monocular asymmetrical OKN is seen with poor response when the drum is rotated from the nasal to temporal direction
110
Lattice degeneration:
* found in 8% of the population
* causes 25% of the retinal detachment
* has a higher incidence amongst the high myopes
* retinal detachment usually occurs due to tear at the periphery of the degeneration rather than due to the hole within the lattice
* extensive cases are better treated with cryotherapy
111
Scleritis:
* many varieties and some have a higher incidence of systemic association than other. In decreasing order: necrotizing scleritis without inflammation ie. scleromalacia perforans (over \>90%), nodular and necrotizing scleritis (50%), diffuse scleritis (30%) and posterior scleritis (10%)
* severe pain is common
* serous retinal detachment is a known complication especially with posterior scleritis
* in mild to moderate scleritis, oral non-steroidal anti-inflammatory agents such as dicoflenac are useful in suppressing the inflammation
* glaucoma occurs in 5% of cases and is related to: steroid use, increased episcleral venous pressure and rarely angle closure glaucoma due to choroidal effusion
112
X-linked condition:
* Fabry's disease is an **X-linked recessive disorder** caused by the deficiency of the enzyme galactosidase
* Norrie's disease is an **X-linked recessive disorder** with ocular dysgenesis with progressive auditory and mental impairment.
* Choroideremia is an **X-linked recessive disorder** with bilateral progressive degeneration of the choriocapillaris.
113
Accommodative esotropia:
* there is overconvergence associated with accommodation
* most patients have a hypermetropia of +2.00 dioptres or more
* age of presentation is between 18 months and 4 years
* binocular fusion is usually good
* unlike infantile esotropia, inferior oblique overaction is not a feature
114
Alexander's law
nystagmus increases in amplitude and frequency as the patient looks in the direction of the fast phase
115
Brown's syndrome:
* caused by a taut superior oblique tendon
* slight downshooting on adduction is common and widening of the palpebral fissure on adduction
* the condition may resolve spontaneously and therefore surgery is not usually indicated
* surgery include superior oblique tenotomy with silicone expander or superior oblique tenotomy with ipsilateral inferior oblique recession to prevent post-operative inferior oblique overaction
116
Corneal blood staining:
* seen in 5% of hyphaema
* caused by passage of erythrocyte breakdown product into the stroma
* it is commoner in: recurrent hyphaema, large hyphaema, presence of endothelial dysfunction and elevated intraocular pressure
* clearing of the staining typically begins peripherally and move centrally. This may take months or years
117
Corneal grafts:
* zenografts refer to transplant between two different species
* isografts refer to transplant between two identical twins
* lamellar keratoplasty is not suitable for Fuch's dystrophy where the endothelium is non-functioning
* blood transfusion does not appear to affect graft survival. In some transplant like renal, previous transfusion actually has a positive effect
* broken suture can elicit neovascularization leading to increased rejection
118
Cystoid macular oedema:
* visually insignificant CMO occurs in about 15% of patients undergoing extracapsular cataract extract as demonstrated by fluorescein angiography. Visually significant CMO only occurs in about 1% of these patients
* the risk of CMO is higher in intracapsular cataract extraction than extracapsular extraction
* other risk factors include: prolapsed vitreous, malpositioned of the intraocular lens and post-operative endophthalmitis.
119
Fourth nerve palsy can be treated by three surgical approaches:
* strengthening of the ipsilateral superior oblique such as tucking
* weakening of ipsilateral inferior oblique (myectomy or recession)
* weakening of the contralateral inferior rectus (recession)
120
Iron deposition in the cornea:
* Fleischer's ring occurs at the base of keratoconus
* Hudson-Stahli's line is a normal ageing change
* Stocker's line is found in front of a pterygium
* Ferry's line is found in front of a bleb
* iron deposition is commonly seen near incisions of radial keratotomy
121
Medication and contact lenses:
* contraceptive pill may cause poor tear secretion and interfere with contact lens wear
* rifampicin causes discoloration of secretion including the tear which may stain the contact lens
122
Ocular parasites:
* Trichinella spiralis causes trichinosis which is an infestation of striated muscle by the larva. They are acquired through eating undercooked pork. The orbit and the upper lid can become infested leading to inflammation and pain on eye movement.
* Loa loa is acquired through bites from Mango flies . The patients presents with pruritic subcutaneous swelling. Ocular manifestation include migration of worms under the conjunctiva, in the anterior chamber and the vitreous
* Leishmania donovani can cause either cutaneous or / and visceral leishmaniasis. It is transmitted by the bite of sandfly. In cutaneous form, the eyelids may become involved and untreated can lead to interstitial keratitis.
123
Sickle cell disease:
* sickle cell trait occurs in 8% of the population
* although SS disease has the most severe systemic manifestation, retinopathy is most severe with SC and S-thal diseases
* neovascularization typically occurs in the peripheral retina
* salmon patches are the result of pre-retinal or internal lining membrane haemorrhages
* the main cause of visual loss is vitreous haemorrhage and rhegmatogenous retinal detachment.
124
Tentorial herniation:
* occurs when a mass lesion makes one cerebral hemisphere too large for its compartment and cause the infero-medial part of the cerebral hemisphere to be pushed through the tentorial hiatus ( which separates the cerebrum from the cerebellum)
* the increased pressure causes vomiting
* deterioration of consciousness occurs due to disturbance of the reticular formation
* compression on the third nerve results in dilated pupil, ocular palsy and ptosis
* results in coning with the whole brainstem being pushed downward. This interfere with the vital functions of respiration (controlled by medulla oblongata)
* compression of the pyramidal fibres result in hemiparesis
125
Cystoid macular oedema without fluorescein leakage occurs in
* some cases of retinitis pigmentosa
* X-linked juvenile retinoschisis
* Goldman-Favre syndrome
* nicotinic acid maculopathy
126
Rhegmatogenous retinal detachment is associated with
* posterior vitreous detachment
* lattice degeneration
* cystic retinal tuft
* meridional folds
* white without pressure
127
Acute macular neuroretinopathy
* an uncommon condition which causes paracentral scotoma in young adult
* fundoscopy reveals dark lesion in the macula which is typically triangular in shape
* otherwise the fundus is normal
* the lesion is confined to the macula and therefore the ERG is normal
* the visual loss is mild and spontaneous recovery is common
128
von Hippel-Lindau's syndrome
* is an autosomal dominant condition with variable penetrance
* 50% of the patients has angiomatosis retinae which may be found in the optic disc or the periphery
* those in the optic disc or juxtapapillary may mimic choroidal neovascularization
* the angioma enlarges slowly leading to visual loss mainly through exudative maculopathy and also vitreous haemorrhage, tractional retinal detachment or epiretinal membrane
129
Stargardt's disease
* is usually inherited in an autosomal recessive inheritance
* it is regarded as a type of fundus flavimaculatus
* lipofuscin substance is found within the REP cells which give rise to dark choroid during fluorescein angiography
* colour vision defect along the red-green axis is common
* in late stage the macula can assume bull's eye maculopathy
* most patients become symptomatic within the first or second decade of life
130
Wyburn-Mason's syndrome
* a type of phakomatoses
* sporadic condition
* characterized by arteriovenous communications of the retina and brain beginning in adolescence
* the arteriovenous communications of the retina gives rise to racemose aneurysm of the retina
* unlike von Hippel Lindau syndrome, exudative maculopathy is uncommon instead the visual loss is due to the loss of capillary bed or overlying of the vessels over the macula
* visual field defect is seen in one-third of the patient due to the vascular abnormalities
131
Electrophysiology
* EOG is useful in detecting Best's disease but is normal in adult onset foveomacular dystrophy
* electroretinogram is abnormal in carrier of X-linked retinitis pigmentosa and is diagnostic in Leber's congenital amaurosis
* in Stargardt's disease, the ERG is variable and is therefore not useful for diagnosis
* carrier of choroideremia has normal ERG despite changes in the peripheral retina
132
Bietti's crystalline dystrophy
* it is an autosomal recessive disorders
* is characterized by crystalline deposits in all layers of the retina, cornea and also in the lymphocytes
* the crystals are made up of cholesterol and lipid
* REP and choroidal atrophy are common features
* patients present with night blindness and progressive visual loss
* ERG and EOG are abnormal
133
Mucopolysaccharidosis associated with pigmentary retinopathy include
* Type I-H (Hurler)
* Type I-S (Scheie)
* Type II (Hunter)
* Type III (Sanfilippo's)
* Type IV (Morquio's)
Type VI (Maroteaux-Lamy's syndrome) and type VII (Sly's syndrome) are not associated with pigmentary retinopathy
134
Optically empty vitreous (due to vitreous liquefaction) and peripheral retinal pigmentary changes occur in:
* Stickler's syndrome
* Jansen's disease
* Wagner's disease
* Goldmann-Favre disease
135
Jansen's disease and Wagner's disease
* both conditions are autosomal dominant
* high myopia, cataract and glaucoma are common in both conditions
* the ERG are abnormal in both conditions
* the EOG are normal in both conditions
* the main distinguishing feature is the increased risk of retinal detachment in Jansen's disease which is not seen in Wagner's disease
136
Macroaneurysms
* are more common in women than men
* found mainly along the temporal arcade
* causes retinal artery occlusion, retinal haemorrhages and vitreous haemorrhages
* symptomatic only if it bleeds or causes exudative maculopathy, spontaneous closure is common due to thrombosis
* IRVAN syndrome is made up of Idiopathic Retinal Vasculitis, Aneurysms and Neuroretinitis. It is characterized by bilateral multiple bilateral macroaneurysms
137
Carcinoma associated retinopathy (CAR)
* is a paraneoplastic syndrome
* colour vision defect, night blindness and rapid visual loss are typical presentation
* the condition may present before the diagnosis of the primary tumour which is typically oat cell carcinoma of the lung
* autoantibodies are commonly seen in the blood
* both rod and cone ERG are abnormal
* there is no effective treatment
138
Deafness and pigmentary retinopathy are seen in the following conditions
* Congenital syphilis
* Congenital rubella
* Usher's syndrome
* Cockaryne's syndrome
* Alstroms syndrome
* Leber's amaurosis
* Alport's syndrome
* Hunter's syndrome (MP II)
* San Fillipo's disease (MP III)
139
Norrie's disease
* a rare X-linked disorders
* bilateral blindness with abnormal retina development
* rosette formation is common in retina histology
* 1/3 has hearing abnormality
* retrolental masses are common which may be mistaken for retinoblastoma
140
X-linked retinoschisis
* splitting of the retina occurs at the nerve fibre layer
* electrophysiology reveals negative ERG with normal a wave but reduced b wave
* the main cause of visual loss is central macular abnormalities
* other causes of visual loss include retinal detachment and vitreous haemorrhage
* hypermetropia is an association
* DNA analysis is useful in detecting the carrier, the abnormal gene is located at XLRS1gene on the short arm of the X-chromosome
*
141
Significant macular oedema as defined by ETDRS are
* retinal thickening within 500 microns of the centre of the fovea
* hard exudate within 500 microns of the centre of the fovea with adjacent retinal thickening
* one disc area of retinal thickening, any part of which is within 1 disc diameter of the centre of the fovea
142
Branch Retinal Vein Occlusion Study
* no treatment for macular oedema for at least 3 months
* fluorescein angiography is not useful at the time of presentation due to retinal haemorrhages, it is only useful when the haemorrhages clear
* laser treatment is useful in patients with vision of 6/12 or less and without evidence of macular ischaemia on fluorescein angiography
* although sectorial panphotocoagulation is useful in reducing the risk of vitreous haemorrhage in those patients who have more than 5 disc diameter of ischaemia, the recommendation is for the PRP to be performed only in the presence of neovascularization and not based on ischaemia of more than 5 disc diameter as the majority of the eyes do not develop neovascularization
143
Findings of the Diabetes Control and Complications Trial are
* intensive insulin treatment resulted in a statistically significant reduction in incidence and progression of DR and the need for macular laser panphotocoagulation or PRP
* these only apply to insulin dependent diabetic
* initial worsening during the first year was noted in some eyes, but after 3 years there was a beneficial effect on progression of DR
* severe hypoglycaemia was more common in the tight control group
144
In intermittent exotropia
* tinted glasses are useful if bright light constitutes a major dissociative factor and allow the patient better control the deviation
* concave glasses are useful in stimulating accommodation and convergence
* orthoptic exercise is useful but is rarely successful if the deviation is more than 15 prism dioptre
* base-in prism is used preoperative to control the deviation and is usually in combination with exercise
* miotic decreases accommodation and therefore make the exotropia worse
145
Post-operative esotropia
* a small degree of consecutive esotropia is desirable and usually decreases as the effect of the surgery is lessen.
* postoperative diplopia is common and usually resolves within 2 weeks.
146
In fourth nerve palsy
* deviation of the eye in fourth nerve palsy depends on which eye is the fixating eye. If the fixating eye is the right eye, then the left eye will become hypodeviated and vice versa
147
Feature of congenital fourth nerve palsy include
* absence of cyclotorsion
* higher vertical fusional amplitude
Abnormal head posture occurs in any long-standing fourth nerve palsy as a compensatory device and is not specific to congenital palsy.
148
Features in favour of bilateral fourth nerve palsy include
* slight hyperdeviation in primary position
* reversal of hyperdeviation and diplopia on lateral versions
* large V pattern
* chin depression being the main abnormal head posture with little or no head tilt
* extorsion of more than 10 degrees
* positive Bielchowsky head tilt test with head tilt to either shoulder
149
Sixth nerve palsy
* the esotropia is worse for distant than near
* face turn to the affected side
* duction is better than version and therefore the ocular movement is better when the unaffected side is closed
* V pattern is common on upgaze
150
Microtropia
* a common form of anomalous binocular single vision
* the strabismus is 10 prism dioptres or less
* the squinting eye has reduced vision
* anisometropia is found in most cases
* stereopsis is reduced but rarely absent
* foveal suppression scotoma is present in the affected eye and can be tested by placing a base out 4 dioptre prism over the affected eye; there is absent of eye movement.
151
Spasmus nutans
* consists of nystagmus, involuntary head movement and abnormal head posture
* usually begins between 3 to 18 months of age
* nystagmus is jerky but of small amplitude and high frequency
* involuntary head movement can be either head nodding or shaking or both
* most resolves by 3 years of age
* rarely associated with neurologic dysfunction but in some cases may be associated with glioma of the chiasm
152
Accommodative esotropia
* usually occurs around 2 years of age
* patients with accommodative esotropia usually suppress the deviating eye and therefore diplopia is uncommon; however due to the suppression amblyopia is common unless the patient has alternating esotropia
* there is usually hypermetropia of greater than +3.00D or a high AC/A ratio
153
154
Cerebral Malaria
155
Malarial Retinopathy
* Retinal haemorrhages
* Typically blot haemorrhages, white centres
* Retinal Whitening
* Typically around the fovea, temporal raphe, peripheries
* Vessel discolouration
* Orange or white
* Papilloedema
156
Early Visual Milestones
157
Normal Visual Development
158
Eye muscles
159
Treatment of Childhood Glaucoma
160
Secundary Glaucomas
