Ophthalmology

• Hypoxia of the retina leads to development of new vessels which subsequently may form fibrous and glial tissue.

• Gliosis and fibrosis in the new vessels from the retina onto the posterior vitreous interface may cause retinal traction and retinal detachment.

• New blood vessels can also grow into the angle of the anterior chamber of the eye (rubeosis iridis) leading to neovascular or rubeotic glaucoma.

• Rubeotic glaucoma is a serious complication with visual loss and raised intra-ocular pressure, resulting eventually in acute severe periorbital pain, corneal oedema, and optic atrophy.

• Advanced diabetic eye disease can remain asymptomatic for a long time, due to the slow progression of proliferative retinopathy.

• Diabetic retinopathy screening is an important factor in early identification and following timely laser, may prevent development of advanced disease.

• The anterior segment

• The cornea

• The sclera

• The iris

• The lens

• The aqueous humour.

• The posterior segment

• The vitreous humour

• The retina

• The neuro-sensory layer

• The photoreceptors (rods and cones)

• The retinal pigment epithelium (RPE)

• Bruch’s membrane

• The choroid

• The macula

• The fovea

• The retinal vasculature

• The optic nerve.

• The appearance of a healthy fundus

• Normal variations:

• Pigmentation

• RPE changes

• Glare

• Pseudophakia

• Tortuous vessels

• Tigroid fundus

• Myopic crescent.

• Maculopathy is one of the commonest causes of blindness in the Western world.

• In diabetic populations diabetic maculopathy causes blindness in 80% of cases due to diabetic retinopathy (DR).

• It is defined as a disease of the macula region located within the retina.

• Screening for diabetic maculopathy and identification of surrogate markers for clinically significant macula oedema (CSMO) will identify sight-threatening maculopathy at a stage when there is the best potential laser treatment outcome.

• There are three main types of maculopathy: exudative, ischaemic, and cystoid maculopathy due to diabetes, all of which have a detrimental effect on visual acuity (VA) if untreated.

• Laser photocoagulation remains the main treatment for diabetic retinopathy (DR).

• Laser photocoagulation is unlikely to improve vision once it has decreased but is effective in stabilizing vision.

• Treatment with intra-vitreal drugs for maculopathy is a major development.

• Optical coherence tomography is an invaluable new imaging tool for DR.

• Pars plana vitrectomy is available for advanced DR.

• When screening the diabetic population for diabetic retinopathy (DR), many other retinal conditions will be identified.

• The most common conditions which may be diagnosed as DR are retinal vein and artery occlusion, hypertensive retinopathy, arterial emboli, and retinal changes due to blood disorders, for example, anaemia. These need local protocols for medical management.

• Familiarity and pattern recognition are important to recognize common abnormalities, for example, drusen, chorioretinitis, asteroides hyalosis, choroidal naevi, and age-related macula degeneration.

• Pre-proliferative retinopathy precedes proliferative retinopathy (new vessel growth) and is therefore an indication that the eye will soon be affected byadvanced stages of retinopathy

• Pre-proliferative retinopathy indicates chronic retinal ischaemia due to blocked capillaries and the clinical signs include

• Multiple cotton wool spots

• Venous beading and/or looping

• Multiple deep round and blot haemorrhages

• Intra-retinal microvascular abnormalities.

• New vessels arise on the optic disc (NVD) or on the retinal surface (NVE) due to retinal ischaemia and growth factors (VEGF and others). The new vessels help re-vascularize the hypoxic (oxygen-starved) tissue.

• New vessels can easily rupture, leading to haemorrhage and severe visual loss.