Gradual loss of vision | Flashcards
(127 cards)
1
Q
What is a cataract?
A
Any opacity on or within the lens
2
Q
How does the incidence of cataracts change with age?
A
Incidence increases with age - by age of 100 years, incidence of cataracts is 100%
3
Q
What are the main structures of the lens from front to back (5)?
A
- Anterior lens capsule
- Lens epithelium
- Cortex
- Lens nucleus
- Posterior lens capsule
4
Q
What are the different causes of cataracts (8)?
A
- Age
- Trauma
- Metabolic
- Toxic
- Secondary (complicated)
- Maternal infection
- Maternal drug ingestion
- Hereditary
5
Q
What are the 3 types of age-related cataracts?
A
- Subcapsular cataracts
- Anterior subcapsular
- Posterior subcapsular - Nuclear sclerotic cataract
- Cortical cataract
6
Q
How would a patient with a posterior subcapsular cataract typically present? (2)
A
- Trouble with bright sunlight/oncoming headlights
2. Reading vision affected more than distance vision
7
Q
How would a patient with a nuclear sclerotic cataract typically present?
A
Myopic shift up to 3 diopters
8
Q
What are cortical cataracts?
What configuration do they form?
A
Opacification of lens cortex
Radial spoke-like configuration
9
Q
Do all cataract patients need surgery?
A
No - only if it affects their vision
10
Q
What are the 2 types of diabetic cataracts?
A
- Age-related cataract + diabetes (cataract appears earlier)
- True diabetic cataract
11
Q
In what group of diabetics do age-related cataracts appear earlier?
A
Non-insulin dependent diabetes
12
Q
Why does cataract surgery not benefit all patients with diabetes to the same extent?
A
They may have retinopathy as well
13
Q
What are the features of a true diabetic cataract?
A
Osmotic overhydration of the lens - lens epithelium is leaky so fluid flows from anterior chamber into lens itself
Causing posterior or anterior lens opacities - snowflake opacities
14
Q
What is the role of the lens epithelium?
A
Controls flow of fluid from anterior chamber into lens
15
Q
How can you classify cataracts according to stage of development (3 stages)?
A
- Immature cataract
- Mature cataract
- Hypermature cataract
16
Q
What is a immature cataract?
A
Cataract hasn’t involved the whole lens
17
Q
What is a mature cataract?
A
When the cortex is totally opaque
18
Q
What is a hypermature cataract?
A
A mature cataract, where the lens material has become smaller and lens capsule is wrinkled due to leakage of water out the lens
19
Q
What are the other metabolic causes of cataract (excluding diabetes)
- 2 common
- 4 rare
A
Common:
- Galactosaemia
- Hypocalcaemic syndromes
Rare
- Mannosidosis
- Fabry’s disease
- Lowe’s
- Wilson’s disease
20
Q
Metabolic disease are more common causes of cataracts in what age groups?
A
Congenital or infantile
21
Q
What are the 5 types of cataracts caused by trauma?
A
- Penetrating eye injuries – direct damage to lens
- Blunt injury – iris pigment imprinted onto lens
- Glass Blower’s cataract – infared radiation affects anterior lens capsule
- Electric shock
- Ionising radiation
22
Q
What are the 3 toxic causes of cataracts?
A
- Corticosteroids (systemic/topical) – causes posterior subcapsular cataract
- Chlorpromazine – fine yellow deposits anterior lens capsule
- Chemotherapy e.g. busulphan
23
Q
What are the 4 secondary complicated causes of cataracts?
A
- Anterior uveitis
- Hereditary retinal degenerations
- Retinitis pigmentosa
- Gyrate atrophy
- Stickler’s syndrome - High myopia
- Glaucomflecken – small grey white anterior subcapsular cataract
24
Q
What are 3 maternal infections and 2 drug ingestions that cause cataracts?
A
Maternal infections:
- Rubella
- Toxoplasmosis
- CMV
Drugs:
Thalidomide, corticosteroids
25
How common are cataracts caused by maternal rubella infection?
50% - of mothers infected during pregnancy in 1st/2nd trimester get cataracts. After 6 weeks gestation, virus can cross lens capsule
26
What are 4 syndromes associated with cataracts?
1. Down's syndrome
2. Alport's syndrome
3. Werner's syndrome
4. Rothmund's syndrome
27
What is retinitis pigmentosa (4)?
1. Genetic disorder of the eyes that causes loss of vision
2. Symptoms include trouble seeing at night and decreased peripheral vision
3. Involves the progressive loss of rod photoreceptor cells in the back of the eye. This is generally followed by loss of cone photoreceptor cells
4. Eventually leads to tunnel vision
28
What is gyrate atrophy (5)?
1. An inherited disorder characterized by progressive vision loss
2. There is an ongoing atrophy in the retina and choroid
3. In childhood, they experience myopia, night blindness, resulting in tunnel vision
4. Many also develop cataracts
5. Eventually leads to blindness by around the age of 50
29
What is Stickler's syndrome (2)?
1. A group of hereditary conditions characterized by a distinctive facial appearance, eye abnormalities, hearing loss, and joint problems.
2. Many have severe nearsightedness (high myopia), abnormal vitreous, glaucoma, cataracts and retinal detachment, which can cause impaired vision or blindness
30
What is high myopia (2)?
1. If the eye requires -6.0 diopters or more of lens correction
2. Increases risk of cataract, retinal detachment and glaucoma
31
What are glaucomflecken?
Small grey-white epithelial and anterior cortical lens opacities that occur followin an episode of markedly elevated IOP, as in acute angle closure glaucoma
32
In the management of cataracts, what are the 7 things you need to assess in a patient?
1. Degree of disability
2. Patient's opinion - do they want it?
3. Best corrected visual acuity i.e. after a recent refraction
4. Coexisting ocular pathology
5. General health, serious cardiac or respiratory disease
6. Age of the patient is not a contraindication for cataract surgery
7. No need to wait until cataract 'matures'
33
What are 4 important aspects to ask about regarding degree of disability with cataracts?
1. Does it bother them?
2. Affects reading, driving?
3. Affects occupation
4. Impact on household work, watching TV?
34
What are the 2 main issues regarding best corrected visual acuity when going into cataract surgery
1. You can change the refraction error, so need to know recent spectacle correction
2. If you make one eye emmotropic, and the other eye is still myopic, the eye can only tolerate a certain difference in power between the eyes otherwise it will lead to double vision
- could do surgery in one eye, followed by the other eye (not together for safety reasons)
- or if patient doesn't want surgery in the other eye, balance power in the eye being operated on so they can see without diplopia
35
What 2 main issues regarding coexisting ocular pathology need to be addressed when a patient undergoes cataract surgery?
1. Need to check for e.g. macular degeneration - the patient may not have as good a result following cataract surgery if they have coexisting pathologies, which needs to be explained to patient beforehand
2. Check for glaucoma as the high pressures can complicate surgery and lead to expulsive haemorrhage or complete loss of vision
36
What is the management of cataracts?
1. Biometry - calculation of required intraocular lens power
| 2. Operations - usually phacoemulsification
37
What are the 3 things that the biometry calculation is based on?
1. Corneal dioptric power
2. Axial length of the eye
3. IOL formula
38
What refraction are patients usually corrected to with biometry?
Slightly myopic so they can have some reading vision
39
What is the main type of cataract operation?
Phacoemulsification
40
How is phacoemulsification done (5)?
1. Small incision from 2.5-3.5
2. Anterior lens capsule is peeled in a circular fashion, known as capsulorrhexis
3. High frequency ultrasound phaco probe is used to fragment and aspirate the lens nucleus
4. Lens cortex is aspirated with irrigation and aspiration probe
5. Foldable intraocular lens made up of acrylic and silicone is inserted through the wound which then unfolds in the lens capsule bag with anterior opening
41
What are the 3 advantages of phacoemulsification?
1. Small incision, fast recovery - frequently manage to see 6/6 next day - although generally takes 2 weeks
2. Good refractive results, very little astigmatism
3. Quick operation
42
What are 4 complications of cataract surgery?
| How frequently do they occur?
1. Posterior capsule opacification (20-40%) over the next few years
2. Vitreous loss (4%)
3. Retinal detachment (1%)
4. Endophthalmitis (0.1%)
43
What are the 5 clinical features of acute bacterial endophthalmitis?
1. Pain and marked visual loss
2. Absent or poor red reflex
3. Corneal haze
4. Fibrinous exudate
5. Hypopyon (inflammatory cells in the anterior chamber of the eye)
44
What are the 3 common causative organisms of acute bacterial endophthalmitis?
1. Staph. epidermidis
2. Staph. aureus
3. Pseudomonas sp
45
What is glaucoma?
Term used to describe a number of disorders by which the intraocular pressure (IOP) is elevated to damage the optic nerve and normal visual process
46
What structure produces aqueous?
Where does it go before it is drained?
Ciliary body
Goes into the posterior chamber, through pupil into anterior chamber, and then is drained
47
What drains the aqueous humour?
Trabecular meshwork
| Then goes into collecting channels, then into venous system of superficial eye
48
Where is the trabecular meshwork?
On the angle between the cornea and the iris
| It is 360 degrees around the eye
49
What equipment needs to be used to see the trabecular meshwork?
Contact lens with LA
50
What are the 3 different classifications of glaucoma?
1. Primary vs secondary
2. Open versus closed
3. Congenital vs acquired
51
What is the general pathogenesis of glaucoma (5)?
1. Aqueous humour drains through the trabecular meshwork
2. Over time, the trabecular meshwork undergoes morphological changes, the cause of which not known, which impair drainage
3. This leads to a rise in intraocular pressure (IOP)
4. IOP is transmitted to the optic disc where nerve fibre damage occurs
52
What are the 2 main factors that influence the level of IOP in the eyes?
1. The rate of aqueous humour production
| 2. The resistance of the drainage of the aqueous humour
53
Which is the most common type of glaucoma?
(Progressive/primary) open angle glaucoma
| POAG
54
What are the 5 risk factors for open angle glaucoma?
1. Raised IOP
2. Family history
3. Myopia
4. Black race
5. Diabetes
55
What is the pathology of progressive/primary open angle glaucoma (6)?
**********
1. Raised IOP +/- vascular factors at optic nerve head (disc)
2. Loss of retinal nerve fibres
3. Optic disc excavation (cupping)
4. Visual field defects (peripheral)
5. Tunnel vision
6. Blindness (if left untreated)
56
In POAG, what percentage of nerve fibres do you need to lose before get:
1. A noticable field defect?
2. Symptomatic
What does this mean clinically?
1. ~30-40% of nerve fibres
2. 90% until you are symptomatic
Means that it is an asymptomatic disease until you are almost blind
57
What are the 4 things you need to examine for in POAG?
1. Optic disc assessment
- increased cup-disc ratio
2. Intraocular pressure readings
3. Visual field analysis
4. Visual acuity
58
What is the disability associated with glaucoma (2)?
1. Significant peripheral field loss may result in patient unable to legally drive
2. Advanced glaucoma results in permanent blindness
59
What are 4 the clinical features of POAG?
1 .Elevated IOP > 21 mmHg
2. Open angle
3. Glaucomatous cupping
4. Peripheral visual field loss
60
Is POAG usually unilateral or bilateral?
Bilateral
61
Is POAG slowly or quickly progressive?
Chronic, slowly progressive
62
Is POAG more common in males/females?
Neither
63
What is the ISNT rule for a normal size of optic disc?
The inferior neuroretinal rim of the disc should be larger than the superior rim, which should be larger than the nasal rim, which should be larger than the temporal rim
64
Is the blind spot temporal or nasal?
Temporal
65
Where do people with glaucoma often experience visual field defects?
Superiorly
66
What are the changes in visual field defects over time in a patient with glaucoma (5)?
1. Starts with a second blind spot superiorly/superior-nasally (usually unnoticed by patient)
2. Later, there is an extension of the superior blind spot around in an arcuate fashion, called a scotoma, which finishes at the horizonal raphe.
A lower scotoma may also appear
3. As time goes on there is a larger loss of vision in an arcuate distribution even to the brightest parts. May go unnoticed if its in one eye, but if bilateral, may be noticed
4. After a longer amount of time, only central vision is preserved and an area on the temporal side called the temporal island (patient will notice this)
5. Without treatment, there is loss of central vision, with only vision in temporal side
67
In a patient with POAG and severe visual field loss, with only central and temporal island preserved, what happens to their visual acuity?
Can be normal
68
In a patient with PAOG and severe visual field loss, with their loss of central vision, what happens to their visual acuity?
They can't read the chart
69
What determines progression in POAG?
IOP
70
What is the rule regarding visual field in defects with optic nerve disease?
The visual field defect does not cross the horizontal midline in optic nerve disease
71
What are the 3 principles of management of POAG?
1. Reducing IOP
2. Monitoring visual field loss
3. Monitoring visual acuity
72
What are the 3 treatment options of POAG?
1. Medical therapy
- topical
- systemic
2. Argon laser trabeculoplasty/selective laser trabeculoplasty
3. Surgical - trabeculectomy
73
What is the treatment goal of the medical treatment of POAG?
To reduce IOP to prevent further optic nerve damage and visual field progression
74
What is the target reduction of IOP?
By 30%
75
What are the 5 families of eye drops that can be used as medical treatment to lower IOP?
1. Prostaglandin agonist
2. Beta blockers
3. Carbonic anhydrase inhibitors
4. Alpha adrenergic agonist
5. Cholinergic miotics
76
What is the most common topical prostaglandin agonist used?
Latanoprost 0.005% qhs
77
How do prostaglandin agonists work?
Lower IOP by increasing the uveoscleral outflow of aqueous humour
78
What are 3 side effects of prostaglandin agonists?
1. Melanin deposition in iris
2. Conjunctival congestion
3. Increase in length of eyelashes
79
What are 3 contraindications of prostaglandin agonists?
1. Uveitis
2. Cystoid macular oedema
3. Pregnancy
80
What is the most common topical beta-blocker used in treatment of POAG?
Timolol 0.25-0.5% bd
81
How do beta-blockers work in treatment of POAG?
Reduces IOP by decreasing the aqueous secretion
82
What are the 6 contraindications for beta-blockers in treatment of POAG?
1. Asthma
2. COPD
3. Heart block
4. Congestive heart failure
5. Depression
6. Myasthenia gravis
83
What are the 2 most common topical alpha adrenergic agonist used in treatment of POAG?
Apraclonidine (0.5 to 1%) tds
| Brimonidine (0.2%) tds
84
How do alpha adrenergic agonists work in treatment of POAG?
Reduce IOP by decreasing the aqueous secretion - have quick action but effective for short periods of time (3-6 months)
85
What is a contraindication of the use of alpha adrenergic agonists?
In patients on monoamine oxidase therapy - can cause hypertensive crisis
86
What are 7 side effects of the use of topical alpha adrenergic agonists in the treatment of POAG?
1. Dryness of the mouth
2. Dryness of the eyes
3. Lethargy
4. Mydriasis
5. Hypotension
6. Dizziness
7. Allergy
87
What are the 2 commonly used topical carbonic anhydrase inhibitors in the treatment of POAG?
Dorzolamide (2%) tds
Brinzolamide (1%) tds
88
How do topical carbonic anhydrase inhibitors work in the treatment of POAG?
Reduce aqueous secretion
89
What are the 4side effects of topical carbonic anhydrase inhibitors in the treatment of POAG?
1. Burning sensation in the eyes on instillation
2. Bitter taste
3. Topical allergy
4. Acidosis
90
What is a commonly used cholinergic/miotic in the treatment of POAG?
What type of glaucoma is it most commonly used for?
Pilocarpine (1-4%)
Commonly used in acute angle closure
91
How do cholinergics/miotics work in the treatment of POAG?
Constricts the pupil and releases the iris tissue from blocking the angle structures
92
What are 4 contraindications of cholinergics/miotics in the treatment of POAG?
1. High myopia
2. Retinal holes
3. Retinal detachments
4. Aphakia (absence of lens)
93
What are 3 side effects of cholinergics/miotics in the treatment of POAG?
1. Can cause accommodative spasm in patients above 40 years of age
2. Eye ache
3. Dim vision
94
What is a systemic therapy that can be used in POAG?
Carbonic anhydrase inhibitors
95
What are 2 common systemic carbonic anhydrase inhibitors used in the treatment of POAG?
Acetazolamide
Diamox (125 to 500mg)
Given IV or orally bd to tds depending on IOP and urgency of IOP reduction
96
What are 2 contraindications of systemic carbonic anhydrase inhibitors in the treatment of POAG?
1. Renal stones
| 2. Sulpha allergy
97
What are 4 systemic side effects of systemic carbonic anhydrase inhibitors in the treatment of POAG?
1. Metabolic acidosis
2. Hypokalaemia
3. Parasthaesia of fingers and toes
4. Nausea and vomiting
98
How does argon laser trabeculoplasty work?
What are its 2 disadvantages?
The argon laser, directed at the trabecular meshwork, induces changes to encourage it to drain more fluid, leading to lower IOP
1. Effect is not permanent
2. Repeat treatment is not effective
99
What is the advantage of selective laser trabeculoplasty over argon laser?
It can be repeated (selective is more common in UK)
100
What are 2 indications for a surgical trabeculectomy?
1. Patient needs an especially low IOP to stop POAG progressing
2. Patient intolerant to drops, or laser does not work
101
What are 3 reasons for poor compliance of eye drops in the treatment of POAG?
1. Hard to administer drops
2. Side effects - can be life threatening
3. Forgetting
102
What are side effects of topical beta-blockers in the treatment of POAG?
Cardiac (heart block) and respiratory effects
103
How does a trabeculectomy work (5)?
1. A controlled fistula is formed for aqueous to seep out of the anterior chamber under the conjunctiva
2. Incision can be in the conjunctiva at:
-at limbus (between cornea and sclera)
OR
-reflect conjunctiva over limbus
3. In both cases, it creates a trapdoor, of a partial thickness of sclera at the top of the eye.
4. The sclera is reflected over the cornea, then an internal sclerostomy is done (a portion of internal sclera is removed), then the flap is put back and sutured in place to control flow of aq out of eye
5. Then conjunctiva is sutured back together allowing aqueous to flow gently out the eye through the hole, under the trap door and collect under the conjunctiva to form a trabeculectomy drainage bleb
104
What is a risk in the lifetime of a trabeculectomy?
Trabeculectomy bleb infection
105
What are the 5 risk factors for failure of a trabeculectomy?
1. Previous surgery
2. Black race
3. Long term topical medications (especially pilocarpine)
4. Coexisting uveitis (past or present)
5. Diabetes (esp with retinopathy)
106
When is failure of a trabeculectomy most likely to occur?
First 6 months
107
Why does trabeculectomy failure occur?
Scarring
108
What is acute angle closure glaucoma (primary)?
A condition whereby obstruction to the aqueous outflow (drainage) is due to the closure of the angle by the peripheral iris to the lens so aq humour can't pass through the pupil, and crowding of the anterior chamber angle, preventing aqueous access to the trabecular meshwork. It is usually predisposed by the anatomy of the eye e.g. hypermetropic
109
Is acute angle closure glaucoma usually uni or bilateral?
Blateral
110
Is acute angle closure glaucoma more common in females or males?
Females:males
4:1
111
What are the 3 symptoms and 3 signs of acute angle closure glaucoma?
Acute high pressure eye
1. Pain in and around eye due to sudden increase in IOP
2. Blurred vision, rapid progressive impairment of vision
3. Nausea + vomiting
1. Corneal oedema (sudden increase in IOP)
2. Red eye
3. Fixed mid-dilated pupil
112
What are 4 risk factors for acute angle closure glaucoma?
1. Family history: eye size and shape
2. Hypermetropia (smaller globes - shorter axial length)
3. Shallow anterior chamber
4. Increasing lens size
113
How urgently does acute angle closure glaucoma need to be treated?
Emergency
114
What is the acute management of acute angle closure glaucoma (4)?
```
1. Intensive miotic therapy (4% pilocarpine eye drops every 5 mins)
PLUS
2. IV/oral acetazolamide
PLUS
3. Analgesia
4. Anti-emetics
```
115
What is the principle of treatment of the acute phase of acute angle closure glaucoma?
Urgent reduction of IOP to avoid irreversible damage to the optic nerve and preservation of vision
116
How does intensive miotic therapy work in the treatment of acute angle closure glaucoma?
Constricts the pupil and therefore pulls the peripheral iris away from the angle
117
How does acetazolamide work in the treatment of acute angle closure glaucoma?
Reduces aqueous secretion
118
What is important to remember in the treatment of acute angle closure glaucoma?
To treat the unaffected eye prophylactically
119
Following the acute phase, what is the treatment of acute angle closure glaucoma (2)?
1. Peripheral laser iridotomy (hole in iris) in both eyes to allow direct drainage of aqueous from the posterior to anterior chamber
2. Resistant cases can be given a trabeculectomy
120
What is secondary glaucoma?
Glaucoma that is due to pathologies not primarily involving drainage apparatus including the trabecular meshwork
121
What are 5 secondary causes of glaucoma?
1. Inflammatory e.g uveitis
2. Neovascular e.g. 2o to DR or CRVO
3. Pigment dispersion syndrome
4. Pseudoexfoliation syndrome
5. Traumatic hyphaema
122
What CRVO?
central retinal vein occlusion
123
How does CRVO lead to glaucoma?
Retinal ischaemia releases vasoproliferative factors causing new blood vessels to grow, especially on surface of iris and peripheral of iris, crossing the trabecular meshwork. With the vessels, scar tissue also forms, which contracts, closing off the angle, causing high pressure
124
What are 2 symptoms and 4 signs of glaucoma secondary to CRVO?
1. Pain
2. Reduced vision (due to corneal oedema or vein occlusion
1. Red eye
2. Corneal oedema
3. Rubeosis - new bv on iris
4. Pupil distortion
125
How does uveitis cause 2o glaucoma?
1. Acute
2. Chronic
1. Rapid onset inflammation, obstruction of intertrabecular spaces and subsequent increased IOP
2. Repeated bouts of uveitis leading to fibroblastic infiltration and formation of scar tissue that slowly obstructs the anterior chamber angle
126
How does DR cause glaucoma?
DR leads to ocular ischaemia, espcially retinal ischaemia, which may result in anterior segment neovascularisation. New vessels grow across the surface of the iris into the angle, closing it off and within the trabecular meshwork which becomes blocked
127
What are the consequences of patient non-compliance, delayed diagnosis and treatment failure in glaucoma?
Blindness
