Homonymous hemianopia- A stroke occurring within the optic tract (post chiasm projection to the lateral geniculate nucleus of the thalamus), results in a homonymous hemianopia. The nasal visual field on the affected side, and the temporal retinal shield on the unaffected side are affected. The patient will complain of frequently bumping into things.
Glaucoma- This is a condition characterised by progressive visual loss and optic nerve damage. A rise in intraocular pressure is a major risk factor (possibly sue to decreased drainage of the aqueous humor in the anterior chamber of the eye). The condition is divided into closed angle and open angle. Open angle is painless, and develops chronically over time. Closed angle is also chronic, but is usually painful and may present acutely. The patient may also complain of sudden blurred vision, nausea and vomiting.
Pituitary Tumour- The pituitary gland sits in the sella turcica, a bony cavity within the body of the sphenoid bone. This cavity lies directly beneath the optic chiasm. If the pituitary gland enlarges e.g. due to a tumour, the tumours may compress the chiasm from beneath. This affects the fibers that cross over (from the temporal visual fields, which corresponds to the nasal retina), and results in bitemporal hemianopia. Patients lose their peripheral vision, which results in the patient knocking into things as they walk or drive.
Diabetic retinopathy- Glucose in the micro-arteries of the retina is very damaging. Changes to the retina occur, following from the ischaemia. Cotton wool spots, flame haemorrhages, exudates and aneurysms result. In advanced disease, neovascularisation begins, and may affect the macula, compromising the patient’s central high quality vision.