Week 2.02 Cataract Flashcards
Forward vs backward light scatter
- When light reaches cataract, it can scatter backwards (away from eye) or forwards (onto the retina)
What are the three types of cataract
Cortical
Nuclear
Posterior sub capsular
What are the risk factors for cortical cataract
- Increasing age
- UV exposure
- Diabetes?
- Particularly found inferior nasal – superior part protected by orbital brow - sun hitting inferior nasal light the most
What are the sxs of cortical cataract
- Cannot get glasses clean
- Difficulty night driving
- Difficulties reading
- Double vision
What does cortical cataract look like
Spoke like capacities
Periphery mainly, spoke encroaches into centre
If only periphery no vision loss
What are the risk factors of nuclear cataract
- age
- smoking - more longer and heavier the more likely
- diabetes?
What are the sxs of nuclear cataract
Possible increases in short sightedness - myopic shift
What kind of cataract might a person have if they come in saying they couldn’t see at near before and now they can
Nuclear cataract
2nd sight of the elderly —> px who doesn’t wear rx for glasses e.g +2.50 spheres for reading, myopic shift become myopic and then are able to read without glasses
What are sxs of nuclear cataract
- Difficulty night driving
- Problems on sunny days
- Colour vision changes – blue appears black, light blue appears grey
What does nuclear cataract look like
Absorbs blue light so appears yellow
Only cataract that absorbs light
What are the risk factors for posterior subcapsular cataract
- age
- smoking
- diabetes
- oral steroid use
- other eye diseases - retinitis pigmentosa
- trauma
Sxs of posterior sub capsular cataract
- middle of pupil, visually debilitating
- vision especially poor with glare and near work
- can occur in younger age groups
- early can be difficult to spot - have to dilate and find if suspect
What does posterior subcapsular cataract look like
Located superior to posterior capsule
In centre and typically round
(Just looks like a wound indent)
When should you refer px for cataract surgery
Determined by when the cataract causes vision loss that affects lifestyle: should be supported by clinical vision loss such as visual acuity, contrast sensitivity or glare testing
What is the pen light glare test
Glare test measures VA or CS when a peripheral glare source is shone into the eye
Simplest test is to remeasure VA when a light from a penlight or direct ophthalmoscope is shone into the eye
Need to standardise light output and test distance
Why do we usually do both eye surgery
- Can cause huge anisometropia – emmetropic in the eye with surgery whilst -5 in the other
- Reduced stereopsis – problems judging things
- Improvements found in mobility-orientation, avoidance of obstacles, face perception , driving
