2: Cataracts Flashcards
Define cataracts
Opacification of the lens
What are immature cataracts
Red-reflex still in tact
What are dense cataracts
No red-reflex visible
What are nuclear cataracts
Change in refractive index - causing dull colours
What are posterior sub capsular cataracts
Progress faster. Occur just deep to the lens. Present with dazzling of lights in bright sunlight and when driving at night.
What causes posterior sub capsular cataracts
Glucocorticoid use
What increases dot opacities
Diabetes and myotonic dystrophy
What is the commonest cause of preventable blindness
Cataracts
How does incidence of cataracts change with age
Increases with age (75% of over 65’s)
What gender are cataracts more common
Female
How should an individual with congenital cataracts be managed and why
Urgent referral to surgery before 6W to prevent development of amblyopia
What is amblyopia
‘Cortical blindness’ - individual will be unable to see despite glasses or contact lenses
What investigation should be ordered in congenital cataracts
TORCH screen
What does a TORCH screen entail
Toxoplasmosis
Other: VZV, parvovirus B19, syphillis, listeriosis
Rubella
CMV
HSV
What is a non-modifiable risk factor for cataracts
Age
What are 4 co-morbidities associated with acquired cataracts
- Diabetes
- Myotonic dystrophy
- HIV
- Wilson’s disease
What medication increases risk of posterior sub capsular cataracts
Glucocorticoids
What are 3 physical risk factors for cataracts
- Trauma
- Radiation
- Sunlight
What 2 lifestyle factors increase risk of cataracts
Smoking
Alcohol
Explain onset of symptoms in cataracts
Gradual onset of blurred vision
How will unilateral cataracts present
May go unnoticed expect loss of depth perception
What is a loss of depth perception called
Stereopsis
How may bilateral cataracts present
Gradual loss of vision presents as:
- Having to change glasses prescription frequently
- Dazzling bright lights
- Monocular diplopia
What do patients with cataracts often report
- Halos around streetlights and difficultly driving at night
Will near of distance vision be impacted more in cataracts
Near and far distance will be impacted equally
What will nuclear cataracts present with
Loss of colour vision
What will posterior sub capsular cataracts present with
Dazzle from bright light
What are 2 differential diagnosis for cataracts
Open-angle glaucoma
Macular degeneration
Explain pathology of cataracts
- Normally light enters eye
through the lens - In cataracts there is
precipitation of protein in the
lens causing opacification - This distorts the light which is refracted and dispersed over the retina
What does lens enable
Accommodation
What are the 3 parts of the lens
Nucleus
Cortex
Capsule
What is the nucleus of the lens
Innermost part of the lens
What is the cortex
Transparent fibres that surround the lens
What happens as we age to the cortex
There are more layers of transparent fibres that are added
What is the capsule
Elastic fibres that holds the nucleus and cortex
What connects to the capsule
Zonnules
What do zonnules connect
Connect to ciliary bodies
What does changing the shape of the capsule enable
Accommodation reflex
What investigations are ordered in cataracts
Automated perimetry
Ophthalmoscopy
Slit Lamp
How will automated perimetry present in cataracts
Normal
What will be seen on ophthalmoscopy in cataracts
Loss of red reflex
What is the red reflex
Orange discolouration caused by reflection of light from the retina
Why is red reflex lost in cataracts
As cataract prevents light hitting the retina
What are the non-surgical methods of managing cataracts
Change glasses prescription
Brighter lights
What is the problem with conservative measures for cataracts
Optimise vision but do not slow down progression of cataracts
What are the indications for surgery in cataracts
- Significant visual impairment
- Impact QOL
- Patient choice
Explain procedure of cataracts
Capsule is cut
Lens is fragmented
Plastic IOL is inserted in its place
Capsule is re-attacged
What is the most common complication of cataract surgery
1 in 10 will need further laser surgery for opacification behind posterior capsule
What is the criteria for Group I license in cataracts
- Read a number plate more than 20m
2. Visual acuity must be at least 6/12
What is the criteria for group II license in cataracts
- Visual acuity of 6/7.5 in better eye and 6/60 in other eye.
- Can’t wear glasses corrective more than +/I 8 diopters
Define partial sightedness
Visual acuity of <6/60. Or >6/60 with visual field impairment.
Define blindness
Visual acuity <3/60 or >3/60 with significant visual field loss
Who does the decision that someone is ‘blind’ lie with
Local authorities. opthalmologists make an application which Is voluntary, not statutory.
What is the advantage of claiming blindness
Benefits
Reduction TV fees
Trave concession
Tax allowances
What are the 3 most common cause of blindness worldwide
- Cataracts
- Glaucoma
- Age-related macular degeneration
