Biochem: Metabolic Profile----->Eye Flashcards
What is the importance of bicarb ion transport in the cornea?
The cornea contains keratin sulphate GAGs which keep the cornea transparent but also increase tonicity in the cornea and attract water from the aqueous humor.
So the cornea secretes bicarb into the aqueous humor to make increase tonicity in the humor which prevents water from entering the cornea. This also helps keep the cornea transparent.
The cornea is avascular, how does it receive nutrients?
Nutrients diffuse to the cornea thru the aqueous humor.
Why does the aqueous humor have 3-4x more lactate than the plasma?
The aqueous humor removes metabolic waste from the cornea and lens which are both avascular. For this reason they operate with mainly anaerobic metabolism which produces lactate.
What is the difference between open angle and closed angle glaucoma?
Both result from increased intraocular pressure due to blockage of the canal of Schlemm.
Open angle results from waste products or debris blocking the drainage canal.
Closed angle resuts from a decrease in the angle between the cornea and iris usually resulting from prolonged contraction of the dilator pupillae muscle.
Gold Standard treatment for open angle glaucoma.
Prostaglandin Analogs
ex. Latanoprost
What is posterior vitreous detachment?
Occurs mostly in elderly. The vitrous humor becomes more fluid and detaches from the retina. Patients claim to see flashing lights and floaters.
What is the mechanism of diabetic cataracts?
- High blood glucose causes accumulation of glucose in the vitreous humor and in the lens.
- Excess glucose is converted into sorbitol.
- Sorbitol increases osmolarity in the lens and water content increases.
- The crystalin proteins are hydrated and aggregate which scatters the light.
What is the difference between dry and wet macular degeneration and what is a treatment for wet macular degeneration?
Dry macular degeneration is a gradual breakdown of cells in the macula.
Wet macular degeneration results from blood vessels growing beneath the macula and leaking causing damage to macular cells. Treated with VEGF inhibitors to prevent vessel growth.
