Retinal Vein Occlusion
The inner layers of the eye are full of blood vessels (arteries and veins). Arteries carry oxygen and other essential nutrients to all issues of the body including the eye. Veins drain the deoxygenated blood from all issues so that it returns to the heart and lungs to bind oxygen again to be transferred back to all organs including the eye. Atherosclerosis is a process which involves the inner lining of the arteries. With age, the inside of the arteries becomes narrower because of atherosclerotic plaques slowly developing. This whole process results in the hardening of the arteries. Blood clots can also form, further reducing blood flow or even totally cutting off the circulation within the artery. Veins and arteries run close together and can cross over each other. When a hardened artery presses on a nearby vein, the vein can be blocked and then a retinal vein occlusion occurs.
The impaired blood flow within the vein causes accumulation of fluid and blood stasis within the retina. At this stage retinal function begins to decline as the retinal cells do not receive enough nutrients. If the central retinal vein is involved we have a Central Retinal Vein Occlusion (CRVO). When only a branch of the retinal vein is occluded, we have a Branch Retinal Vein Occlusion (BRVO). A CRVO is more serious than BRVO because a greater part of the retinal blood supply is affected.
Risk Factors
The exact cause of the retinal vein occlusion is sometimes unknown but the following risk factors have been associated with the condition :
- Diabetes
- Hypertension
- Glaucoma
- High cholesterol
- Smoking
It is very important to treat all above conditions in case a patient has a vein occlusion in one eye in order to prevent recurrence in the fellow eye. Patients should also quit smoking for obvious reasons.
Diagnosis
Diagnosis is made with retinal scans and a special retinal angiogram (Fundus Fluorescein Angiogram or FFA) which shows the exact location and extend of the affected retinal vessels. The accumulation of fluid in the central part of the retina is the main cause for visual loss.
Treatment
Treatment can be offered with antiVEGF injections just like wet Age Related Macular Degeneration. Another treatment option is steroid implants introduced in the eye which last longer (for few months) but potentially can cause a cataract to progress in the same eye or glaucoma.
Finally in cases of retinal vein occlusion, abnormal blood vessels may grow inside the eye and can cause internal bleeding or glaucoma. To prevent these complications, application of retinal laser treatment is usually required.
Patients will need to be followed up frequently to monitor the condition and to assess the need for repeat injections as these usually last for few weeks or months. Intraocular pressure also needs monitoring to prevent the development of glaucoma.