Age-related macular degeneration accounts for more than 54% of all vision loss in the white population in the USA. An estimated 8 million Americans are affected with early age-related macular degeneration, of whom over 1 million will develop advanced age-related macular degeneration within the next 5 years. In the UK, age-related macular degeneration is the cause of blindness in almost 42% of those who go blind aged 65–74 years, almost two-thirds of those aged 75–84 years, and almost three-quarters of those aged 85 years or older.

Macular degeneration is more likely to be found in Caucasians than in people of African descent.

Studies indicate drusen associated with AMD are similar in molecular composition to Beta-Amyloid (βA) plaques and deposits in other age-related diseases such as Alzheimer's disease and atherosclerosis. This suggests that similar pathways may be involved in the etiologies of AMD and other age-related diseases.

All people with "diabetes mellitus" are at riskthose with Type I diabetes and those with Type II diabetes. The longer a person has diabetes, the higher their risk of developing some ocular problem. Between 40 and 45 percent of Americans diagnosed with diabetes have some stage of diabetic retinopathy. After 20 years of diabetes, nearly all patients with Type I diabetes and >60% of patients with Type II diabetes have some degree of retinopathy; however, these statistics were published in 2002 using data from four years earlier, limiting the usefulness of the research. The subjects would have been diagnosed with diabetes in the late 1970s, before modern fast acting insulin and home glucose testing.

Prior studies had also assumed a clear glycemic threshold between people at high and low risk of diabetic retinopathy.

However, it has been shown that the widely accepted WHO and American Diabetes Association diagnostic cutoff for diabetes of a fasting plasma glucose ≥ 7.0 mmol/l (126 mg/dl) does not accurately identify diabetic retinopathy among patients. The cohort study included a multi-ethnic, cross-sectional adult population sample in the US, as well as two cross-sectional adult populations in Australia. For the US-based component of the study, the sensitivity was 34.7% and specificity was 86.6%. For patients at similar risk to those in this study (15.8% had diabetic retinopathy), this leads to a positive predictive value of 32.7% and negative predictive value of 87.6%.

Published rates vary between trials, the proposed explanation being differences in study methods and reporting of prevalence rather than incidence values.

During pregnancy, diabetic retinopathy may also be a problem for women with diabetes.

It is recommended that all pregnant women with diabetes have dilated eye examinations each trimester to protect their vision.

People with Down's syndrome, who have extra chromosome 21 material, almost never acquire diabetic retinopathy. This protection appears to be due to the elevated levels of endostatin, an anti-angiogenic protein, derived from collagen XVIII. The collagen XVIII gene is located on chromosome 21.

STGD1 is the most common form of inherited juvenile macular degeneration with a prevalence of approximately 1 in 10,000 births.

Familial transmission is now recognized in a small proportion of people with MacTel type 2; however, the nature of any related genetic defect or defects remains elusive. The MacTel genetic study team hopes that exome analysis in the affected population and relatives may be more successful in identifying related variants.

Optic pits occur equally between men and women. They are seen in roughly 1 in 10,000 eyes, and approximately 85% of optic pits are found to be unilateral (i.e. in only one eye of any affected individual). About 70% are found on the temporal side (or lateral one-half) of the optic disc. Another 20% are found centrally, while the remaining pits are located either superiorly (in the upper one-half), inferiorly (in the lower one-half), or nasally (in the medial one-half towards the nose).

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.

No particular risk factors have been conclusively identified; however, there have been a few reports that demonstrate an autosomal dominant pattern of inheritance in some families. Therefore, a family history of optic pits may be a possible risk factor.

Although a variety of complex classification schemes are described in the literature, there are essentially two forms of macular telangiectasia: type 1 and type 2. Type 1 is typically unilateral and occurs almost exclusively in males after the age of 40.

Type 2 is mostly bilateral, occurs equally in males and females.

Cystoid macular edema (CME) involves fluid accumulation in the outer plexiform layer secondary to abnormal perifoveal retinal capillary permeability. The edema is termed "cystoid" as it appears cystic; however, lacking an epithelial coating, it is not truly cystic. The cause for CME can be remembered with the mnemonic "DEPRIVEN" (diabetes, epinepherine, pars planitis, retinitis pigmentosa, Irvine-Gass syndrome, venous occlusion, E2-prostaglandin analogues, nicotinic acid/niacin).

Diabetic macular edema (DME) is similarly caused by leaking macular capillaries. DME is the most common cause of visual loss in both proliferative, and non-proliferative diabetic retinopathy.

The long-term prognosis for patients with Stargardt disease is widely variable although the majority of people will progress to legal blindness.

Stargardt disease has no impact on general health and life expectancy is normal. Some patients, usually those with the late onset form, can maintain excellent visual acuities for extended periods, and are therefore able to perform tasks such as reading or driving.

This ocular pathology was first described by Iwanoff in 1865, and it has been shown to occur in about 7% of the population. It can occur more frequently in the older population with postmortem studies showing it in 2% of those aged 50 years and 20% in those aged 75 years.

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.

The pathogenesis of GA is multifactorial and is generally thought to be triggered by intrinsic and extrinsic stressors of the poorly regenerative retinal pigment epithelium (RPE), particularly oxidative stress caused by the high metabolic demand of photoreceptors, photo-oxidation, and environmental stressors such as cigarette smoke. Variations in several genes, particularly in the complement system, increase the risk of developing GA. This is an active area of research but the current hypothesis is that with aging, damage caused by these stressors accumulates, which coupled with a genetic predisposition, results in the appearance of drusen and lipofuscin deposits (early and intermediate AMD). These and other products of oxidative stress can trigger inflammation via multiple pathways, particularly the complement cascade, ultimately leading to loss of photoreceptors, RPE, and choriocapillaris, culminating in atrophic lesions that grow over time.

Vitelliform macular dystrophy or vitelliform dystrophy is an irregular autosomal dominant eye disorder which can cause progressive vision loss. This disorder affects the retina, specifically cells in a small area near the center of the retina called the macula. The macula is responsible for sharp central vision, which is needed for detailed tasks such as reading, driving, and recognizing faces. The condition is characterized by yellow (or orange), slightly elevated, round structures similar to the yolk (Latin "vitellus") of an egg.

Geographic Atrophy (GA), also known as atrophic age-related macular degeneration (AMD) or advanced dry AMD, is an advanced form of age-related macular degeneration that can result in the progressive and irreversible loss of retina (photoreceptors, retinal pigment epithelium, choriocappillaris) which can lead to a loss of visual function over time. It is estimated that GA affects >5 million people worldwide and approximately 1 million patients in the US, which is similar to the prevalence of neovascular (wet) AMD, the other advanced form of the disease.

The incidence of advanced AMD, both geographic atrophy and neovascular AMD, increases exponentially with age and while there are therapies for wet AMD, GA currently has no approved treatment options. The aim of most current clinical trials is to reduce the progression of GA lesion enlargement.

A cone dystrophy is an inherited ocular disorder characterized by the loss of cone cells, the photoreceptors responsible for both central and color vision.

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.

"Best disease" is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In most cases, an affected person has one parent with the condition.

The inheritance pattern of adult-onset vitelliform macular dystrophy is definitively autosomal dominant. Many affected people, however, have no history of the disorder in their family and only a small number of affected families have been reported. This is because the penetrance of the condition is incomplete; therefore, it is possible for an individual to have a copy of the mutant allele and not display the VMD phenotype. The ratio of males to females is approximately 1:1.

This may be present in conditions causing traction on the retina especially at the macula. This may occur in:

a) The vitreomacular traction syndrome; b) Proliferative diabetic retinopathy with vitreoretinal traction; c) Atypical cases of impending macular hole.

In the UK, screening for diabetic retinopathy is part of the standard of care for people with diabetes. After one normal screening in people with diabetes, further screening is recommended every two years. Teleophthalmology has been employed in these programs.

There is no good evidence for any preventive actions, since it appears this is a natural response to aging changes in the vitreous. Posterior vitreous detachment (PVD) has been estimated to occur in over 75 per cent of the population over age 65, that PVD is essentially a harmless condition (although with some disturbing symptoms), and that it does not normally threaten sight. However, since epiretinal membrane appears to be a protective response to PVD, where inflammation, exudative fluid, and scar tissue is formed, it is possible that NSAIDs may reduce the inflammation response. Usually there are flashing light experiences and the emergence of floaters in the eye that herald changes in the vitreous before the epiretinal membrane forms g

Drusen are associated with aging and macular degeneration are distinct from another clinical entity, optic disc drusen, which is present on the optic nerve head. Both age-related drusen and optic disc drusen can be observed by ophthalmoscopy. Optical coherence tomography scans of the orbits or head, calcification at the head of the optic nerve without change in size of globe strongly suggests drusen in a middle-age or elderly patient.

Whether drusen promote AMD or are symptomatic of an underlying process that causes both drusen and AMD is not known, but they are indicators of increased risk of the complications of AMD.

'Hard drusen' may coalesce into 'soft drusen' which is a manifestation of macular degeneration.

Despite its name, the "presumed" relationship of POHS to "Histoplasma capsulatum" is controversial. The fungus has rarely been isolated from cases with POHS, the condition has also been found in locations where histoplasmosis is rare, and there appears to be a relationship with tobacco smoking.