Conditions Of The Eye: Glaucoma, Cataracts And Colour Blindness Flashcards
How does the eye drain fluid?
Aqueous humour is produced in the anterior cavity of the eye by the ciliary processes using carbonic anhydrase. This drains down the trabecular mesh work to the canal of Schlemm, which is connected to anterior ciliary veins. The intraocular pressure is a measure of the resistance of flow of aqueous humour in the trabecular mesh work.
What is the anterior chamber of the eye?
Space between the cornea and the iris containing aqueous humour.
What is the posterior chamber of the eye?
Space between the iris and the optic disc containing vitreous humour.
What is chronic glaucoma?
Open angle glaucoma caused by resistance to flow of aqueous humour in the trabecular mesh work, with a large angle between the iris and lens in the anterior chamber and results in increased intraocular pressure.
There is a slow and gradual onset that causes loss of peripheral vision, headaches and gradual vision loss generally that is worse at night. Cupping of the optic disc occurs.
What are the risk factors for open angle glaucoma?
Myopia (shortsightedness)
Family history
Hypertension due to previous chronic conditions such as diabetes
Long term corticosteroid use
Eye injury
What is acute glaucoma?
Chronic glaucoma which is an opthalmagic emergency caused by the iris bulging forward and creating a reduced angle from the lens that blocks the trabecular mesh work for drainage of the aqueous humour. There is painful red eye and blurred vision which progresses to nausea and vomiting.
What is glaucoma?
Increased intraocular pressure caused by resistance to aqueous humour flow in the trabecular meshwork that can lead to damage to the optic nerve.
What are the risk factors for closed angle glaucoma?
Older Age, Female, East Asian, Family history.
What is the treatment of open angle glaucoma?
Prostaglandin analogues which induce vasodilation
Beta blockers which will reduce aqueous humour production.
Carbonic anhydrase inhibitors which reduce aqueous humour production
Sympathomimetics which reduce aqueous humour production and increase flow out of the eye.
What is the treatment of closed angle glaucoma?
Carbonic anhydrase inhibitors to induce reduction of aqueous humour production.
Pilocarpine eye drops, a miotic which activates the parasympathetic system for reduction in pupil size and opens channels in the trabecular meshwork and induces fluid to drain from the eye
Which type of glaucoma is more common?
Primary open angle glaucoma.
What is cataracts?
Opacity of the lens due to degeneration of the proteins, such as the modified epithelial cells which make it up or the lens capsule. It results in vision loss and is the leading cause of blindness worldwide. With cataracts, secondary vision phenomenon can occur where there is correction of previous myopia.
Who is most commonly affected by cataracts?
Older people
Caucasian
People with endocrine disorders such as diabetes
Men and women are equally affected
What are the risk factors for cataracts?
Smoking
Alcohol
Previous eye trauma
UV radiation
Trauma
Diabetes
How is cataracts treated?
Surgical removal of lens and replacement with artificial lens.
How is glaucoma diagnosed?
Tonometry to measure the intraocular pressure.
->In the optic disc, there is a tiny centre called the optic cup. Because of death of nerve cells in glaucoma, the optic cup becomes larger in comparison to the disc.
Visual perimeter.
