Cataract Flashcards
What is cataract?
It is a clouding of the normally clear lens of the eye, reducing the ability to transmit light
Symptoms?
Blurred vision Increasing difficulty in vision at night Sensitive to light Halos around the light Need for brighter light to see
Development?
It usually develops slowly with no pain.
Early stage
- Cloudiness may affect only a small part of the lens which patient often does not notice
Later stage
- cataract grows larger, it clouds more of the lens which lesser light will reach the retina resulting in vision impairment
In normal lens
- it is made of proteins and fibres and they are arrange d in the way that it makes the lens clear and allow light to pass through
In cataract:
- composition of lens changes
- structure of protein fibres break down and insoluble proteins clump tgt, clouding small areas of the lens
- as cataract develops, clouding becomes more dense and involved greater parts of the lens
associated with oxidative stress
- damage and changes resulting from oxidation
(sources = cellular sources, environment)
- during oxidation, free radicals are produced and protein to protein disulfide bridges are formed which result in polymerization and cross-linking of lipids and proteins. This will increase the insoluble protein and cause clumping which will attack the lipids and proteins of the mem
in diabetic cataract
- glucose is converted to sorbitol which is cannot pass through the plama mem. So it will accumulate inside the cytoplasm which will increase the osmotic pressure in the eye. Water enters to neutralize the hyperosmolarity and this will result in swelling and disruption of the lens fibres and form cataract
Whos at risk
Elderly Diabetes Family history of cataract Previous eye injury Previous eye surgery Smoking Excessive exposure to sunlight
Treatment
Drugs - reverse cataract formation - inhibiting cataract formation Surgery - remove cataract - clear artificial lens is implanted into the empty lens to replace the cataract
