Risk factors for CRAO include the following: being between 60 and 65 years of age, being over the age of 40, male gender, hypertension, caucasian, smoking and diabetes mellitus. Additional risk factors include endocarditis, atrial myxoma, inflammatory diseases of the blood vessels, and predisposition to forming blood clots.

Severe ipsilateral or bilateral carotid artery stenosis or occlusion is the most common cause of ocular ischemic syndrome. The syndrome has been associated with occlusion of the common carotid artery, internal carotid artery, and less frequently the external carotid artery. Other causes include:

- Takayasu's arteritis

- Giant cell arteritis

- Severe ophthalmic artery occlusion, due to thromboembolism.

- Surgical interruption of anterior ciliary blood vessels supplying the eye, particularly during extensive strabismus surgery on 3 or more rectus muscles, leading to an anterior segment ischemic syndrome.

Studies have identified the following abnormalities as risk factors for the development of BRVO:

- hypertension

- cardiovascular disease

- obesity

- glaucoma

Diabetes mellitus was not a major independent risk factor.

Risk factors include:

- Hypertension

- Elevated lipid levels

- cigarette smoking

- Diabetes

With respect to embolic and hemodynamic causes, this transient monocular visual loss ultimately occurs due to a temporary reduction in retinal artery, ophthalmic artery, or ciliary artery blood flow, leading to a decrease in retinal circulation which, in turn, causes retinal hypoxia. While, most commonly, emboli causing amaurosis fugax are described as coming from an atherosclerotic carotid artery, any emboli arising from vasculature preceding the retinal artery, ophthalmic artery, or ciliary arteries may cause this transient monocular blindness.

- Atherosclerotic carotid artery: Amaurosis fugax may present as a type of transient ischemic attack (TIA), during which an embolus unilaterally obstructs the lumen of the retinal artery or ophthalmic artery, causing a decrease in blood flow to the ipsilateral retina. The most common source of these athero-emboli is an atherosclerotic carotid artery. However, a severely atherosclerotic carotid artery may also cause amaurosis fugax due to its stenosis of blood flow, leading to ischemia when the retina is exposed to bright light. "Unilateral visual loss in bright light may indicate ipsilateral carotid artery occlusive disease and may reflect the inability of borderline circulation to sustain the increased retinal metabolic activity associated with exposure to bright light."

- Atherosclerotic ophthalmic artery: Will present similarly to an atherosclerotic internal carotid artery.

- Cardiac emboli: Thrombotic emboli arising from the heart may also cause luminal obstruction of the retinal, ophthalmic, and/or ciliary arteries, causing decreased blood flow to the ipsilateral retina; examples being those arising due to (1) atrial fibrillation, (2) valvular abnormalities including post-rheumatic valvular disease, mitral valve prolapse, and a bicuspid aortic valve, and (3) atrial myxomas.

- Temporary vasospasm leading to decreased blood flow can be a cause of amaurosis fugax. Generally, these episodes are brief, lasting no longer than five minutes, and have been associated with exercise. These vasospastic episodes are not restricted to young and healthy individuals. "Observations suggest that a systemic hemodynamic challenge provoke[s] the release of vasospastic substance in the retinal vasculature of one eye."

- Giant cell arteritis: Giant cell arteritis can result in granulomatous inflammation within the central retinal artery and posterior ciliary arteries of eye, resulting in partial or complete occlusion, leading to decreased blood flow manifesting as amaurosis fugax. Commonly, amaurosis fugax caused by giant cell arteritis may be associated with jaw claudication and headache. However, it is also not uncommon for these patients to have no other symptoms. One comprehensive review found a two to nineteen percent incidence of amaurosis fugax among these patients.

- Systemic lupus erythematosus

- Periarteritis nodosa

- Eosinophilic vasculitis

- Hyperviscosity syndrome

- Polycythemia

- Hypercoagulability

- Protein C deficiency

- Antiphospholipid antibodies

- Anticardiolipin antibodies

- Lupus anticoagulant

- Thrombocytosis

- Subclavian steal syndrome

- Malignant hypertension can cause ischemia of the optic nerve head leading to transient monocular visual loss.

- Drug abuse-related intravascular emboli

- Iatrogenic: Amaurosis fugax can present as a complication following carotid endarterectomy, carotid angiography, cardiac catheterization, and cardiac bypass.

If carotid occlusive disease results in ophthalmic artery occlusion, general ocular ischemia may result in retinal neovascularization, rubeosis iridis, cells and flare, iris necrosis, and cataract. The condition leads to neovascularization in various eye tissues due to the ischemia. The eye pressure may become high due to associated neovascular glaucoma. An ischemic optic neuropathy may eventually occur.

The artery can re-canalize over time and the edema can clear. However, optic atrophy leads to permanent loss of vision. Irreversible damage to neural tissue occurs after only 90 minutes. Two thirds of patients experience 20/400 vision while only one in six will experience 20/40 vision or better.

The mean age of affected patients is 60 years. The right eye is affected more commonly than the left eye which probably reflects the greater possibility of cardiac or aortic emboli traveling to the right carotid artery.

Most of the cases are due to emboli to the retinal circulation. Three main types of retinal emboli have been identified: Cholesterol, calcific, and fibrin-platelet.

In general, BRVO has a good prognosis: after 1 year 50–60% of eyes have been reported to have a final VA of 20/40 or better even without any treatment. With time the dramatic picture of an acute BRVO becomes more subtle, hemorrhages fade so that the retina can look almost normal. Collateral vessels develop to help drain the affected area.

The central retinal vein is the venous equivalent of the central retinal artery and, like that blood vessel, it can suffer from occlusion (central retinal vein occlusion, also CRVO), similar to that seen in ocular ischemic syndrome. Since the central retinal artery and vein are the sole source of blood supply and drainage for the retina, such occlusion can lead to severe damage to the retina and blindness, due to ischemia (restriction in blood supply) and edema (swelling).

It can also cause glaucoma.

Nonischemic CRVO is the milder form of the disease. It may progress to the more severe ischemic type.

Ocular causes include:

- Iritis

- Keratitis

- Blepharitis

- Optic disc drusen

- Posterior vitreous detachment

- Closed-angle glaucoma

- Transient elevation of intraocular pressure

- Intraocular hemorrhage

- Coloboma

- Myopia

- Orbital hemangioma

- Orbital osteoma

- Keratoconjunctivitis sicca

Treatment consists of Anti-VEGF drugs like Lucentis or intravitreal steroid implant (Ozurdex) and Pan-Retinal Laser Photocoagulation usually. Underlying conditions also require treatment. Non-Ischemic CRVO has better visual prognosis than Ischemic CRVO.

A systematic review studied the effectiveness of the anti-VEGF drugs ranibizumab and pagatanib sodium for patients suffering from non-ischemic CRVO. Though there was a limited sample size, participants in both treatment groups showed improved visual acuity over 6 month periods, with no safety concerns.

The two most common causes of retinopathy include diabetic retinopathy and retinopathy of prematurity. Diabetic retinopathy affects about 5 million people and retinopathy of prematurity affect about 50,000 premature infants each year worldwide. Hypertensive retinopathy is the next most common cause affecting anywhere from 3 to 14% of all non-diabetic adults.

This condition is often associated with diabetes in advanced proliferative diabetic retinopathy. Other conditions causing rubeosis iridis include central retinal vein occlusion, ocular ischemic syndrome, and chronic retinal detachment.

Genetic mutations are rare causes of certain retinopathies and are usually X-linked including "NDP" family of genes causing Norrie Disease, FEVR, and Coats disease among others. There is emerging evidence that there may be a genetic predisposition in patients who develop retinopathy of prematurity and diabetic retinopathy. Trauma, especially to the head, and several diseases may cause Purtscher's retinopathy.

As one gets older, pockets of fluid can develop in the vitreous. When these pockets develop near the back of the eye, the vitreous can pull away from the retina and possibly tear it. Posterior vitreous detachment accounts for 3.7–11.7% of vitreous hemorrhage cases.

Less common causes of vitreous hemorrhage make up 6.4–18% of cases, and include:

- Proliferative sickle cell retinopathy

- Macroaneurysm

- Age-related macular degeneration

- Terson syndrome

- Retinal neovascularization as a result of branch or central retinal vein occlusion

- Other – about 7 cases in 100,000 have no known cause attributed to them.

Several other diseases can result in retinopathy that can be confused with hypertensive retinopathy. These include diabetic retinopathy, retinopathy due to autoimmune disease, anemia, radiation retinopathy, and central retinal vein occlusion.

Retinal haemorrhages commonly occur in high attitude climbers, most likely due to the effects of systemic hypoxia on the eye. Risk is correlated with the maximum altitude reached, duration of exposure to high altitude conditions, and climb rate.

Signs of damage to the retina caused by hypertension include:

- Arteriolar changes, such as generalized arteriolar narrowing, focal arteriolar narrowing, arteriovenous nicking, changes in the arteriolar wall (arteriosclerosis) and abnormalities at points where arterioles and venules cross. Manifestations of these changes include "Copper wire arterioles" where the central light reflex occupies most of the width of the arteriole and "Silver wire arterioles" where the central light reflex occupies all of the width of the arteriole, and "arterio-venular (AV) nicking" or "AV nipping", due to venous constriction and banking.

- advanced retinopathy lesions, such as microaneurysms, blot hemorrhages and/or flame hemorrhages, ischemic changes (e.g. "cotton wool spots"), hard exudates and in severe cases swelling of the optic disc (optic disc edema), a ring of exudates around the retina called a "macular star" and visual acuity loss, typically due to macular involvement.

Mild signs of hypertensive retinopathy can be seen quite frequently in normal people (3–14% of adult individuals aged ≥40 years), even without hypertension. Hypertensive retinopathy is commonly considered a diagnostic feature of a hypertensive emergency although it is not invariably present.

It is usually associated with disease processes in the retina, which involve the retina becoming starved of oxygen (ischaemic). The ischemic retina releases a variety of factors, the most important of which is VEGF. These factors stimulate the formation of new blood vessels (angiogenesis). Unfortunately, these new vessels do not have the same characteristics as the blood vessels originally formed in the eye. In addition, new blood vessels can form in areas that do not have them. Specifically, new blood vessels can be observed on the iris. In addition to the blood vessels in the iris, they can grow into the angle of the eye. These blood vessels eventually go through a process called fibrosis which closes the normal physiologic anatomy of the angle. The closing of the angle prevents fluid from leaving the eye resulting in an increase in intraocular pressure. This is called neovascular glaucoma.

Retinal hemorrhage is a disorder of the eye in which bleeding occurs into the light sensitive tissue on the back wall of the eye. A retinal hemorrhage can be caused by hypertension, retinal vein occlusion (a blockage of a retinal vein), or diabetes mellitus (which causes small fragile blood vessels to form, which are easily damaged). Retinal hemorrhages can also occur due to shaking, particularly in young infants (shaken baby syndrome) or from severe blows to the head.

Retinal hemorrhages that take place outside the macula can go undetected for many years, and may sometimes only be picked up when the eye is examined in detail by ophthalmoscopy, fundus photography, or a dilated fundus exam. However, some retinal hemorrhages can cause severe impairment of vision. They may occur in connection with posterior vitreous detachment or retinal detachment.

Risk factors for retinal detachment include severe myopia, retinal tears, trauma, family history, as well as complications from cataract surgery.

Retinal detachment can be mitigated in some cases when the warning signs are caught early. The most effective means of prevention and risk reduction is through education of the initial signs, and encouragement for people to seek ophthalmic medical attention if they have symptoms suggestive of a posterior vitreous detachment. Early examination allows detection of retinal tears which can be treated with laser or cryotherapy. This reduces the risk of retinal detachment in those who have tears from around 1:3 to 1:20. For this reason, the governing bodies in some sports require regular eye examination.

Trauma-related cases of retinal detachment can occur in high-impact sports or in high speed sports. Although some recommend avoiding activities that increase pressure in the eye, including diving and skydiving, there is little evidence to support this recommendation, especially in the general population. Nevertheless, ophthalmologists generally advise people with high degrees of myopia to try to avoid exposure to activities that have the potential for trauma, increase pressure on or within the eye itself, or include rapid acceleration and deceleration, such as bungee jumping or roller coaster rides.

Intraocular pressure spikes occur during any activity accompanied by the Valsalva maneuver, including weightlifting. An epidemiological study suggests that heavy manual lifting at work may be associated with increased risk of rhegmatogenous retinal detachment, but this relationship is not strong. In this study, obesity also appeared to increase the risk of retinal detachment. A high Body Mass Index (BMI) and elevated blood pressure have been identified as a risk factor in non-myopic individuals.

Genetic factors promoting local inflammation and photoreceptor degeneration may also be involved in the development of the disease.

Other risk factors include the following:

- Glaucoma

- AIDS

- Cataract surgery

- Diabetic retinopathy

- Eclampsia

- Family history of retinal detachment

- Homocysteinuria

- Malignant hypertension

- Metastatic cancer, which spreads to the eye (eye cancer)

- Retinoblastoma

- Severe myopia

- Smoking and passive smoking

- Stickler syndrome

- Von Hippel-Lindau disease

The causes of macular edema are numerous and different causes may be inter-related.

- It is commonly associated with diabetes. Chronic or uncontrolled diabetes type 2 can affect peripheral blood vessels including those of the retina which may leak fluid, blood and occasionally fats into the retina causing it to swell.

- Age-related macular degeneration may cause macular edema. As individuals age there may be a natural deterioration in the macula which can lead to the depositing of drusen under the retina sometimes with the formation of abnormal blood vessels.

- Replacement of the lens as treatment for cataract can cause pseudophakic macular edema. (‘pseudophakia’ means ‘replacement lens’) also known as Irvine-Gass syndrome The surgery involved sometimes irritates the retina (and other parts of the eye) causing the capillaries in the retina to dilate and leak fluid into the retina. Less common today with modern lens replacement techniques.

- Chronic uveitis and intermediate uveitis can be a cause.

- Blockage of a vein in the retina can cause engorgement of the other retinal veins causing them to leak fluid under or into the retina. The blockage may be caused, among other things, by atherosclerosis, high blood pressure and glaucoma.

- A number of drugs can cause changes in the retina that can lead to macular edema. The effect of each drug is variable and some drugs have a lesser role in causation. The principal medication known to affect the retina are:- latanoprost, epinephrine, rosiglitazone, timolol and thiazolidinediones among others.

- A few congenital diseases are known to be associated with macular edema for example retinitis pigmentosa and retinoschisis.

Predisposing factors for Postoperative PVR are preoperative PVR, aphakia, high levels of vitreous proteins, duration of retinal detachment before corrective surgery, the size of the retinal hole or tear, intra-ocular inflammation, vitreous hemorrhage, and trauma to the eye. An equation to calculate the patient's risk for acquiring PVR is:

1 is added if the risk factor is present and 0 if the risk factor is absent. A patient is at a high risk for developing PVR is the PVR score is >6.33.