KHIO 1 Flashcards
(55 cards)
Causes of floaters and flashes and when they might occur separately:
- Both
○ PVD
○ Retinal tear
○ RRD
○ Vit. Haem (assoc. Fibrovascular contraction) - Floaters
○ Late PVD
○ Asteroid hyalosis (Ca-Lipid deposit)
○ Uveitis/Vitritis
○ Intraocular tumours - Flashes
○ Early PVD
○ Optic neuritis
○ TRD
DDX flashes:
PVD
Retinal tear
RRD, TRD
Vit. Haem
* Migraine
* Stroke
Patho of myopia:
Dopamine theory: Low outdoor / Increased near work > Low light exposure > decreased dopamine release > increased scleral growth (uninhibited)
Hyperopic defocus: Accommodative lag / Urbanization > Altered signals from retina through to sclera > signalling cascade > axial elongation
Genetic inheritance of myopia:
7%, 25%, 50%
PAX6, GJD2 genes
MYP1/2/3 Loci
Syndromic genes:
- COL2A1 (sticklers)
- FBN1 (Marfans)
IOP changes with time:
Peak in morning due to head position
Types of glaucoma and risk factors:
POAG (common):
* African, FOH
* Myopia, DM
PACG: gradual anatomical closure
* Asian, FOH
* Hyperopia
* Shallow AC
Secondary ACG: Blockage unrelated to anatomy
* Neovasc.
* Traumatic
* Uveitic
* Phacomorphic
* Pupillary block
○ PDX
Secondary OAG:
* Pigmentary: PDS
○ Myopia, males
Steroid induced
Surgical management for glaucoma:
Trabeculectomy: OAG
* Drainage through bleb
Tube shunt:
* Baerveldt implant
SLT: Irritate TM
Laser iridotomy: ACG
Cyclodestruction: removal of CB
Vogt’s limbal girdle:
Benign white opacity at limbus (chalky)
Age/UV/Oxidative stress > collagen degeneration > Ca deposits
* Usually has interval of Vogt
Arcus senilis:
Benign white opacity at limbus
Age/hyperlipidemia > decreased lipid metabolism > aggregation at bowmans layer
* Clear interval of vogt
<50yo needs assesment for hyperlipidema/Cardiovascular evaluation
Peripheral retinal degenerations
Lattice degeneration: Myopia > NS retinal atrophy > thinning
○ Monitored > Laser for high risk
Senile Retinoschisis: Age>50 > peripheral separation of NFL from NSR > cystic cavities
○ Monitor > VF for peripheral defect > Laser/Cryo
X-linked Retinoschisis: RS1 gene > dysfunctional retinoschisin protein > poor retinal structure > separation of all layers of retina > central vision loss
○ Genetic counselling
Pavingstone degeneration: Benign Progressive degeneration of outer retinal layers > adhesion of remaining layers to bruchs
Monitored
Management of retinal holes:
- Observation: small, asymptomatic, low risk (no traction)
- Laser photocoagulation: Vit. Traction, Tears, High risk
○ Argon 488nm blue / 514nm green > Melanin/Haem > chorioretinal adhesions - Cryotherapy: Media opacity
- Pars-Planar Vitrectomy: When laser ineffective
○ Gas retinopexy - Scleral buckle: for developing RRD
In conjunction with laser
Retinal holes:
Full thickness loss of retina
- Operculated hole: PVD > mechanical separation
○ May have operculum
○ Risk RRD
- Focal/Simple hole: Hole where vit. May still be attached
○ RRD if Vit. Is attached
- Horseshoe tear: PVD > Retinal flap
○ High risk RRD; requires Laser
- Atrophic hole: Retinal degeneration (lattice) > hole
○ Asymptomatic
Risk RRD
Signs of retinal detachments:
RRD:
○ Schafer’s
○ Lattice degenerations
○ Dark vessels, corrugated
○ Fl/Fl, Curtain VF defect
TRD:
○ Diabetic, Retinal NMV
○ CWS, microaneurysms, exudates
○ Concave, no breaks
○ Gradual painless loss of vision
Exudative:
Chorioretinitis, Tumour
Stroke types:
Ischemic (90%): Obstruction of BV’s in brain
○ Thrombosis: Blood clot formed in brain
○ Embolism: Plaque debris travels to brain
Haemorrhagic: BV rupture
Ocular effects of stroke:
VF defect: Based on visual pathway loss
Agnosia (recognition): Temporal lobe
Diplopia: CN3 (oculomotor), CN4(Trochlear), CN 6(Abducens)
Anisocoria and Ptosis:
○ CN3 > Mydriasis / Full ptosis
○ Horners > Miosis / Partial ptosis
CN7 > Facial Ptosis
Specific VF defects based on Visual pathway lesion:
○ Amaurosis: AAION
○ Bitemporal hemianopia: Pituitary adenoma
○ Homonymous Hemianopia: Lesion of optic tract / Radiations / Occipital
○ Sup. Quadrantanopia: Temporal lobe Myers loop
○ Inf. Quadrantanopia: Parietal lobe
Central scotoma: Occipital tip
T1DM:
AAD against pancreatic beta cells in islet’ of langerhans > insulin deficiency
○ HLA-DR3/4
Symptoms:
○ Polyuria (urination)
○ Polydipsia (thirst)
○ Polyphagia (hunger)
○ Weight loss
○ Fatigue
Management:
Life long insulin therapy
DDX Epiphora:
Reflex tearing:
○ DED
○ Blepharitis
○ Conjunctivitis
○ Trichiasis
○ Entropion
Lacrimal drainage obstruction:
○ Ectropion
Neurological:
CNV stimulation (Trigeminal neuralgia/HZO)
T2DM:
- Poor diet/physical activity > ^Fat storage > ^Lipid breakdown to glycerol/FFAs
- Chronic elevation of FFAs > insulin resistance / compensatory insulin increase > downregulation of insulin receptors > glucose uptake loss > hyperglycemia
- Chronic hyperglycimia/lipotoxicity(FFAs) > pancreatic-B cell apoptosis > insulin secretion loss
○ Decreased muscle glucose uptake
○ Increased hepatic glucogenesis
^Beta cell insulin production > beta cell failure > Insulin deficiency:
○ Glucotoxicity
Lipotoxicity (^FFAs)
Entropion types:
Involutional: Age > Laxity of lid retractors
Cicatricial: Trachoma, SJS
Spastic: ocular irritation
Congenital: birth defects
Ectropion types:
Involutional: Age > laxity
Cicatricial: Chronic inflammation, burns
Paralytic: CN7 Bells palsy
Mechanical: Lid swelling, Tumor
Congenital: birth defects
Causes of trichiasis:
Chronic blepharitis (common): Lid inflammation > lash misdirection
Trachoma: Conj. Cicatrisation
OCP: AAD > Conj. Fibrosis
SJS: Mucosal inflammation
Trauma, Idiopathic
Entropion and ectropion management:
Conservative:
○ Lubricating drops
○ Lid taping
○ BoTox
○ Moisture chamber (ectropion)
Surgical for entropion:
○ Sutures (temp > involutional)
○ Lower lid retractor reinsertion
○ Mucous membrane grafting
Surgical for ectropion:
○ Lateral tarsal strip (involutional)
Skin grafting (cicatricial
Management of Trichiasis:
Conservative:
○ Lubricating drops > ointments
○ Epilation
Temporary:
○ Electrolysis (lash destruction)
○ Cryotherapy
○ Argon laser
Surgical:
○ Lid rotation
○ Tarsotomy
Mucous membrane grafting