Signs and symptoms of macular degeneration include:

- Visual symptoms

- Distorted vision in the form of metamorphopsia, in which a grid of straight lines appears wavy and parts of the grid may appear blank: Patients often first notice this when looking at things like miniblinds in their home or telephone poles while driving. There may also be central scotomas, shadows or missing areas of vision

- Slow recovery of visual function after exposure to bright light (photostress test)

- Visual acuity drastically decreasing (two levels or more), e.g.: 20/20 to 20/80

- Blurred vision: Those with nonexudative macular degeneration may be asymptomatic or notice a gradual loss of central vision, whereas those with exudative macular degeneration often notice a rapid onset of vision loss (often caused by leakage and bleeding of abnormal blood vessels).

- Trouble discerning colors, specifically dark ones from dark ones and light ones from light ones

- A loss in contrast sensitivity

Macular degeneration by itself will not lead to total blindness. For that matter, only a very small number of people with visual impairment are totally blind. In almost all cases, some vision remains, mainly peripheral. Other complicating conditions may possibly lead to such an acute condition (severe stroke or trauma, untreated glaucoma, etc.), but few macular degeneration patients experience total visual loss.

The area of the macula comprises only about 2.1% of the retina, and the remaining 97.9% (the peripheral field) remains unaffected by the disease. Even though the macula provides such a small fraction of the visual field, almost half of the visual cortex is devoted to processing macular information.

The loss of central vision profoundly affects visual functioning. It is quite difficult, for example, to read without central vision. Pictures that attempt to depict the central visual loss of macular degeneration with a black spot do not really do justice to the devastating nature of the visual loss. This can be demonstrated by printing letters six inches high on a piece of paper and attempting to identify them while looking straight ahead and holding the paper slightly to the side. Most people find this difficult to do.

Patients with idiopathic macular telangiectasia type 1 are typically 40 years of age or older. They may have a coincident history of ischemic vascular diseases such as diabetes or hypertension, but these do not appear to be causative factors.

Macular telangiectasia type 2 usually present first between the ages of 50 and 60 years, with a mean age of 55–59 years. They may present with a wide range of visual impact, from totally asymptomatic to substantially impaired; in most cases however, patients retain functional acuity of 20/200 or better. Metamorphopsia may be a subjective complaint. Due to the development of paracentral scotomota (blind spots), reading ability is impaired early in the disease course. It might be even the first symptom of the disease.

The condition may remain stable for extended periods, sometimes interspersed with sudden decreases in vision. Patients’ loss of visual function is disproportionately worse than the impairment of their visual acuity, which is only mildly affected in many cases. In patients with MacTel, as compared with a reference population, there is a significantly higher prevalence of systemic conditions associated with vascular disease, including history of hypertension, history of diabetes, and history of coronary disease. MacTel does not cause total blindness, yet it commonly causes gradual loss of the central vision required for reading and driving.

Intermediate AMD is diagnosed by large drusen and/or any retinal pigment abnormalities. Intermediate AMD may cause some vision loss, however, like Early AMD, it is usually asymptomatic.

Geographic atrophy (GA) is a chronic disease, which leads to visual function loss. This often results in difficulties performing daily tasks such as reading, recognizing faces, and driving, and ultimately has severe consequences on independence.

Initially, patients often have good visual acuity if the GA lesions are not involved in the central macular, or foveal, region of the retina. As such, a standard vision test may underrepresent the visual deficit experienced by patients who report challenges reading, driving or seeing in low light conditions.

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.

The most common sign at presentation is leukocoria (abnormal white reflection of the retina). Symptoms typically begin as blurred vision, usually pronounced when one eye is closed (due to the unilateral nature of the disease). Often the unaffected eye will compensate for the loss of vision in the other eye; however, this results in some loss of depth perception and parallax. Deterioration of sight may begin in either the central or peripheral vision. Deterioration is likely to begin in the upper part of the vision field as this corresponds with the bottom of the eye where blood usually pools. Flashes of light, known as photopsia, and floaters are common symptoms. Persistent color patterns may also be perceived in the affected eye. Initially, these may be mistaken for psychological hallucinations, but are actually the result of both retinal detachment and foreign fluids mechanically interacting with the photoreceptors located on the retina.

One early warning sign of Coats' disease is yellow-eye in flash photography. Just as the red-eye effect is caused by a reflection off blood vessels in the back of a normal eye, an eye affected by Coats' will glow yellow in photographs as light reflects off cholesterol deposits. Children with yellow-eye in photographs are typically advised to immediately seek evaluation from an optometrist or ophthalmologist, who will assess and diagnose the condition and refer to a vitreo-retinal specialist.

Coats' disease itself is painless. Pain may occur if fluid is unable to drain from the eye properly, causing the internal pressure to swell, resulting in painful glaucoma.

Coats' usually affects only one eye (unilateral) and occurs predominantly in young males 1/100,000, with the onset of symptoms generally appearing in the first decade of life. Peak age of onset is between 6–8 years of age, but onset can range from 5 months to 71 years.

Coats' disease results in a gradual loss of vision. Blood leaks from the abnormal vessels into the back of the eye, leaving behind cholesterol deposits and damaging the retina. Coats' disease normally progresses slowly. At advanced stages, retinal detachment is likely to occur. Glaucoma, atrophy, and cataracts can also develop secondary to Coats' disease. In some cases, removal of the eye may be necessary (enucleation).

Patients with Stargardt disease usually develop symptoms in the mid-first to the late second decade of life, with age of onset which can be as early as ~6 years of age. The main symptom of Stargardt disease is loss of visual acuity, uncorrectable with glasses, which progresses and frequently stabilizes between 20/200 and 20/400. Other symptoms include wavy vision, blind spots (scotomata), blurriness, impaired color vision, and difficulty adapting to dim lighting (delayed dark adaptation). The disease sometimes causes sensitivity to glare; overcast days offer some relief. Vision is most noticeably impaired when the macula (center of retina and focus of vision) is damaged, leaving peripheral vision more intact. Generally, vision loss starts within the first 20 years of life.

Examination with an ophthalmoscope shows few notable findings in the early stages of the disease. Eventually, however, an oval-shaped atrophy with a horizontal major axis appears in the retinal pigment epithelium, and has the appearance of beaten bronze, along with sparing of the area surrounding the optic disc (peripapillary sparing). Techniques such as fundus autofluorescence (FAF), Optical Coherence Tomography (OCT), or less frequently fluorescein angiography, can detect early signs before they are visible ophthalmoscopically.

Optic nerve damage is progressive and insidious. Eventually 75% of patients will develop some peripheral field defects. These can include nasal step defects, enlarged blind spots, arcuate scotomas, sectoral field loss and altitudinal defects. Clinical symptoms correlate to visibility of the drusen. Central vision loss is a rare complication of bleeding from peripapillar choroidal neovascular membranes. Anterior ischemic optic neuropathy (AION) is a potential complication.

Drusen, from the German word for "node" or "geode" (singular, "Druse"), are tiny yellow or white accumulations of extracellular material that build up between Bruch's membrane and the retinal pigment epithelium of the eye. The presence of a few small ("hard") drusen is normal with advancing age, and most people over 40 have some hard drusen. However, the presence of larger and more numerous drusen in the macula is a common early sign of age-related macular degeneration (AMD).

Macular telangiectasia describes two distinct retinal diseases affecting the macula of the eye, macular telangiectasia type 1 and macular telangiectasia type 2.

Macular telangiectasia (MacTel) type 1 is a very rare disease, typically unilateral and usually affecting male patients. MacTel type 2 is more frequent than type 1 and generally affects both eyes (bilateral). It usually affects both sexes equally. Both types of MacTel should not be confused with Age-related macular degeneration (AMD), from which it can be distinguished by symptoms, clinical features, pathogenesis, and disease management. However, both AMD and MacTel eventually lead to (photoreceptor) atrophy and thus loss of central vision.

The etiology of both types of MacTel is still unknown and no treatment has been found to be effective to prevent further progression. Because lost photoreceptors cannot be recovered, early diagnosis and treatment appear to be essential to prevent loss of visual function. Several centers are currently trying to find new diagnostics and treatments to understand the causes and biochemical reactions in order to halt or counteract the adverse effects.

Contemporary research has shown that MacTel type 2 is likely a neurodegenerative disease with secondary changes of the blood vessels of the macula. Although MacTel type 2 has been previously regarded as a rare disease, it is in fact probably much more common than previously thought. The very subtle nature of the early findings in MacTel mean the diagnoses are often missed by optometrists and general ophthalmologists. Due to increased research activity since 2005, many new insights have been gained into this condition since its first description by Dr. J. Donald Gass in 1982.

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.

In most patients, optic disc drusen are an incidental finding. It is important to differentiate them from other conditions that present with optic disc elevation, especially papilledema, which could imply raised intracranial pressure or tumors. True papilledema may present with exudates or cotton-wool spots, unlike ODD. The optic disc margins are characteristically irregular in ODD but not blurred as there is no swelling of the retinal nerve fibers. Spontaneous venous pulsations are present in about 80 percent of patients with ODD, but absent in cases of true disc edema. Other causes of disc elevation clinicians must exclude may be: hyaloid traction, epipapillary glial tissue, myelinated nerve fibres, scleral infiltration, vitreopapillary traction and high hyperopia. Disorders associated with disc elevation include: Alagille syndrome, Down syndrome, Kenny-Caffey syndrome, Leber Hereditary Optic Neuropathy and linear nevus sebaceous syndrome.

"Typical lattice" consists of sharply demarcated, spindle-shaped areas of retinal thinning, usually located between the equator of the retina and the posterior border of the vitreous base. This is more frequently located in the temporal half of the retina and is seen more superiorly than inferiorly.

"Atypical lattice" is characterised by radial lesions which appear continuous with the peripheral blood vessels. This type is typically seen in patients with Stickler syndrome.

Lattice degeneration is a disease of the human eye wherein the peripheral retina becomes atrophic in a lattice pattern and may develop tears, breaks, or holes, which may further progress to retinal detachment. It is an important cause of retinal detachment in young myopic individuals. The cause is unknown, but pathology reveals inadequate blood flow resulting in ischemia and fibrosis.

Lattice degeneration occurs in approximately 6–8% of the general population and in approximately 30% of phakic retinal detachments. Similar lesions are seen in patients with Ehlers-Danlos syndrome, Marfan syndrome, and Stickler syndrome, all of which are associated with an increased risk of retinal detachment. Risk of developing lattice degeneration in one eye is also increased if lattice degeneration is already present in the other eye.

Progressive retinal atrophy (PRA) is a group of genetic diseases seen in certain breeds of dogs and, more rarely, cats. Similar to retinitis pigmentosa in humans, it is characterized by the bilateral degeneration of the retina, causing progressive vision loss culminating in blindness. The condition in nearly all breeds is inherited as an autosomal recessive trait, with the exception of the Siberian Husky (inherited as an X chromosome linked trait) and the Bullmastiff (inherited as an autosomal dominant trait). There is no treatment.

In general, PRAs are characterised by initial loss of rod photoreceptor cell function followed by that of the cones and for this reason night blindness is the first significant clinical sign for most dogs affected with PRA. As other retinal disorders, PRA can be divided into either dysplastic disease, where the cells develop abnormally, and degenerative, where the cells develop normally but then degenerate during the dog's lifetime.

Generalized PRA is the most common type and causes atrophy of all the neural retinal structures. Central progressive retinal atrophy (CPRA) is a different disease from PRA involving the retinal pigment epithelium (RPE), and is also known as retinal pigment epithelial dystrophy (RPED).

Retinoschisis is an eye disease characterized by the abnormal splitting of the retina's neurosensory layers, usually in the outer plexiform layer. Most common forms are asymptomatic, some rarer forms result in a loss of vision in the corresponding visual field.

Many people often do not have symptoms until very late in their disease course. Patients often become symptomatic when there is irreversible damage. Symptoms are usually not painful and can include:

- Vitreous hemorrhage

- Floaters, or small objects that drift through the field of vision

- Decreased visual acuity

- "Curtain falling" over eyes

Stargardt disease, or fundus flavimaculatus, is the most frequent form of inherited juvenile macular degeneration. Stargardt causes progressive vision loss usually to the point of legal blindness. Several genes are associated with the disorder. Symptoms, mainly central vision loss, typically develop before age 20 (median age of onset: ~17 years old), and also include wavy vision, blind spots, blurriness, impaired color vision, and difficulty adapting to dim lighting (dark adaptation delays).

Stargardt is often used to refer to any juvenile macular dystrophy; however, it properly refers to atrophic macular dystrophy with yellow, poorly-defined flecks surrounding the macula in the retinal pigment epithelium.

Diabetic retinopathy often has no early warning signs. Even macular edema, which can cause rapid vision loss, may not have any warning signs for some time. In general, however, a person with macular edema is likely to have blurred vision, making it hard to do things like read or drive. In some cases, the vision will get better or worse during the day.

In the first stage which is called non-proliferative diabetic retinopathy (NPDR) there are no symptoms, the signs are not visible to the eye and patients will have 20/20 vision. The only way to detect NPDR is by fundus photography, in which microaneurysms (microscopic blood-filled bulges in the artery walls) can be seen. If there is reduced vision, fluorescein angiography can be done to see the back of the eye. Narrowing or blocked retinal blood vessels can be seen clearly and this is called retinal ischemia (lack of blood flow).

Macular edema in which blood vessels leak their contents into the macular region can occur at any stage of NPDR. The symptoms of macular edema are blurred vision and darkened or distorted images that are not the same in both eyes. Ten percent (10%) of diabetic patients will have vision loss related to macular edema. Optical Coherence Tomography can show the areas of

retinal thickening (due to fluid accumulation) of macular edema.

In the second stage, abnormal new blood vessels (neovascularisation) form at the back of the eye as part of "proliferative diabetic retinopathy" (PDR); these can burst and bleed (vitreous hemorrhage) and blur the vision, because these new blood vessels are fragile. The first time this bleeding occurs, it may not be very severe. In most cases, it will leave just a few specks of blood, or spots floating in a person's visual field, though the spots often go away after a few hours.

These spots are often followed within a few days or weeks by a much greater leakage of blood, which blurs the vision. In extreme cases, a person may only be able to tell light from dark in that eye. It may take the blood anywhere from a few days to months or even years to clear from the inside of the eye, and in some cases the blood will not clear. These types of large hemorrhages tend to happen more than once, often during sleep.

On funduscopic exam, a doctor will see cotton wool spots, flame hemorrhages (similar lesions are also caused by the alpha-toxin of "Clostridium novyi"), and dot-blot hemorrhages.

Macular edema occurs when fluid and protein deposits collect on or under the macula of the eye (a yellow central area of the retina) and causes it to thicken and swell (edema). The swelling may distort a person's central vision, because the macula holds tightly packed cones that provide sharp, clear, central vision to enable a person to see detail, form, and color that is directly in the centre of the field of view.

This type of retinoschisis is very common with a prevalence of up to 7 percent in normal persons. Its cause is unknown. It can easily be confused with retinal detachment by the non-expert observer and in difficult cases even the expert may have difficulty differentiating the two. Such differentiation is important since retinal detachment almost always requires treatment while retinoschisis never itself requires treatment and leads to retinal detachment (and hence to visual loss) only occasionally. Unfortunately one still sees cases of uncomplicated retinoschisis treated by laser retinopexy or cryopexy in an attempt to stop its progression towards the macula. Such treatments are not only ineffective but unnecessarily risk complications. There is no documented case in the literature of degenerative retinoschisis itself (as opposed to the occasional situation of retinal detachment complicating retinoschisis) in which the splitting of the retina has progressed through the fovea. There is no clinical utility in differentiating between typical and reticular retinoschisis. Degenerative retinoschisis is not known to be a genetically inherited condition.

There is always vision loss in the region of the schisis as the sensory retina is separated from the ganglion layer. But like the loss is in the periphery, it goes unnoticed. It is the very rare schisis that encroaches on the macula where retinopexy is then properly used.

The diagnosis of POHS is based on the clinical triad of multiple white, atrophic choroidal

scars, peripapillary pigment changes (dark spots around optic disc of the eye), and a maculopathy caused by choroidal neovascularization.

Completely distinct from POHS, acute ocular histoplasmosis may rarely occur in immunodeficiency.

A rhegmatogenous retinal detachment is commonly preceded by a posterior vitreous detachment which gives rise to these symptoms:

- flashes of light (photopsia) – very brief in the extreme peripheral (outside of center) part of vision

- a sudden dramatic increase in the number of floaters

- a ring of floaters or hairs just to the temporal (skull) side of the central vision

Although most posterior vitreous detachments do not progress to retinal detachments, those that do produce the following symptoms:

- a dense shadow that starts in the peripheral vision and slowly progresses towards the central vision

- the impression that a veil or curtain was drawn over the field of vision

- straight lines (scale, edge of the wall, road, etc.) that suddenly appear curved (positive Amsler grid test)

- central visual loss

In the event of an appearance of sudden flashes of light or floaters, an eye doctor needs to be consulted immediately. A shower of floaters or any loss of vision, too, is a medical emergency.