The fundus exam via ophthalmoscopy is essentially normal early on in cone dystrophy, and definite macular changes usually occur well after visual loss. Fluorescein angiography (FA) is a useful adjunct in the workup of someone suspected to have cone dystrophy, as it may detect early changes in the retina that are too subtle to be seen by ophthalmoscope. For example, FA may reveal areas of hyperfluorescence, indicating that the RPE has lost some of its integrity, allowing the underlying fluorescence from the choroid to be more visible. These early changes are usually not detected during the ophthalmoscopic exam.

The most common type of macular lesion seen during ophthalmoscopic examination has a bull’s-eye appearance and consists of a doughnut-like zone of atrophic pigment epithelium surrounding a central darker area. In another, less frequent form of cone dystrophy there is rather diffuse atrophy of the posterior pole with spotty pigment clumping in the macular area. Rarely, atrophy of the choriocapillaris and larger choroidal vessels is seen in patients at an early stage. The inclusion of fluorescein angiography in the workup of these patients is important since it can help detect many of these characteristic ophthalmoscopic features. In addition to the retinal findings, temporal pallor of the optic disc is commonly observed.

As expected, visual field testing in cone dystrophy usually reveals a central scotoma. In cases with the typical bull’s-eye appearance, there is often relative central sparing.

Because of the wide spectrum of fundus changes and the difficulty in making the diagnosis in the early stages, electroretinography (ERG) remains the best test for making the diagnosis. Abnormal cone function on the ERG is indicated by a reduced single-flash and flicker response when the test is carried out in a well-lit room (photopic ERG). The relative sparing of rod function in cone dystrophy is evidenced by a normal scotopic ERG, i.e. when the test is carried out in the dark. In more severe or longer standing cases, the dystrophy involves a greater proportion of rods with resultant subnormal scotopic records. Since cone dystrophy is hereditary and can be asymptomatic early on in the disease process, ERG is an invaluable tool in the early diagnosis of patients with positive family histories.

Cone dystrophy in general usually occurs sporadically. Hereditary forms are usually autosomal dominant, and instances of autosomal recessive and X-linked inheritance also occur.

In the differential diagnosis, other macular dystrophies as well as the hereditary optic atrophies must be considered. Fluorescent angiography, ERG, and color vision tests are important tools to help facilitate diagnosis in early stages.

Diagnosis of age-related macular degeneration rests on signs in the macula, irrespective of visual acuity. Diagnosis of AMD may include the following procedures and tests:

- The transition from dry to wet AMD can happen rapidly, and if it is left untreated can lead to legal blindness in as little as six months. To prevent this from occurring and to initiate preventative strategies earlier in the disease process, dark adaptation testing may be performed. A dark adaptometer can detect subclinical AMD at least three years earlier than it is clinically evident.

- There is a loss of contrast sensitivity, so that contours, shadows, and color vision are less vivid. The loss in contrast sensitivity can be quickly and easily measured by a contrast sensitivity test like Pelli Robson performed either at home or by an eye specialist.

- When viewing an Amsler grid, some straight lines appear wavy and some patches appear blank

- When viewing a Snellen chart, at least 2 lines decline

- Preferential hyperacuity perimetry changes (for wet AMD)

- In dry macular degeneration, which occurs in 85–90 percent of AMD cases, drusen spots can be seen in Fundus photography

- In wet macular degeneration, angiography can visualize the leakage of bloodstream behind the macula. Fluorescein angiography allows for the identification and localization of abnormal vascular processes.

- Using an electroretinogram, points in the macula with a weak or absent response compared to a normal eye may be found

- Farnsworth-Munsell 100 hue test and Maximum Color Contrast Sensitivity test (MCCS) for assessing color acuity and color contrast sensitivity

- Optical coherence tomography is now used by most ophthalmologists in the diagnosis and the follow-up evaluation of the response to treatment with antiangiogenic drugs.

An accurate diagnosis of retinitis pigmentosa relies on the documentation of the progressive loss photoreceptor cell function, confirmed by a combination of visual field and visual acuity tests, fundus and optical coherence imagery, and electroretinography (ERG),

Visual field and acuity tests measure and compare the size of the patient's field of vision and the clarity of their visual perception with the standard visual measurements associated with healthy 20/20 vision. Clinical diagnostic features indicative of retinitis pigmentosa include a substantially small and progressively decreasing visual area in the visual field test, and compromised levels of clarity measured during the visual acuity test. Additionally, optical tomography such as fundus and retinal (optical coherence) imagery provide further diagnostic tools when determining an RP diagnosis. Photographing the back of the dilated eye allows the confirmation of bone spicule accumulation in the fundus, which presents during the later stages of RP retinal degeneration. Combined with cross-sectional imagery of optical coherence tomography, which provides clues into photoreceptor thickness, retinal layer morphology, and retinal pigment epithelium physiology, fundus imagery can help determine the state of RP progression.

While visual field and acuity test results combined with retinal imagery support the diagnosis of retinitis pigmentosa, additional testing is necessary to confirm other pathological features of this disease. Electroretinography (ERG) confirms the RP diagnosis by evaluating functional aspects associated with photoreceptor degeneration, and can detect physiological abnormalities before the initial manifestation of symptoms. An electrode lens is applied to the eye as photoreceptor response to varying degrees of quick light pulses is measured. Patients exhibiting the retinitis pigmentosa phenotype would show decreased or delayed electrical response in the rod photoreceptors, as well as possibly compromised cone photoreceptor cell response.

The patient's family history is also considered when determining a diagnosis due to the genetic mode of inheritance of retinitis pigmentosa. At least 35 different genes or loci are known to cause "nonsyndromic RP" (RP that is not the result of another disease or part of a wider syndrome). Indications of the RP mutation type can be determine through DNA testing, which is available on a clinical basis for:

- (autosomal recessive, Bothnia type RP)

- (autosomal dominant, RP1)

- (autosomal dominant, RP4)

- (autosomal dominant, RP7)

- (autosomal dominant, RP13)

- (autosomal dominant, RP18)

- CRB1 (autosomal recessive, RP12)

- (autosomal recessive, RP19)

- (autosomal recessive, RP20)

For all other genes (e.g. DHDDS), molecular genetic testing is available on a research basis only.

RP can be inherited in an autosomal dominant, autosomal recessive, or X-linked manner. X-linked RP can be either recessive, affecting primarily only males, or dominant, affecting both males and females, although males are usually more mildly affected. Some digenic (controlled by two genes) and mitochondrial forms have also been described.

Genetic counseling depends on an accurate diagnosis, determination of the mode of inheritance in each family, and results of molecular genetic testing.

Diagnosis can be established on clinical grounds and this may be enhanced with studies on surgically excised corneal tissue and in some cases with molecular genetic analyses. As clinical manifestations widely vary with the different entities, corneal dystrophies should be suspected when corneal transparency is lost or corneal opacities occur spontaneously, particularly in both corneas, and especially in the presence of a positive family history or in the offspring of consanguineous parents.

Superficial corneal dystrophies - "Meesmann dystrophy" is characterized by distinct tiny bubble-like, punctate opacities that form in the central corneal epithelium and to a lesser extent in the peripheral cornea of both eyes during infancy that persists throughout life. Symmetrical reticular opacities form in the superficial central cornea of both eyes at about 4–5 years of age in "Reis-Bücklers corneal dystrophy". Patient remains asymptomatic until epithelial erosions precipitate acute episodes of ocular hyperemia, pain, and photophobia. Visual acuity eventually becomes reduced during the second and third decades of life following a progressive superficial haze and an irregular corneal surface. In "Thiel–Behnke dystrophy", sub-epithelial corneal opacities form a honeycomb-shaped pattern in the superficial cornea. Multiple prominent gelatinous mulberry-shaped nodules form beneath the corneal epithelium during the first decade of life in "Gelatinous drop-like corneal dystrophy" which cause photophobia, tearing, corneal foreign body sensation and severe progressive loss of vision. "Lisch epithelial corneal dystrophy" is characterized by feather shaped opacities and microcysts in the corneal epithelium that are arranged in a band-shaped and sometimes whorled pattern. Painless blurred vision sometimes begins after sixty years of life.

Corneal stromal dystrophies - "Macular corneal dystrophy" is manifested by a progressive dense cloudiness of the entire corneal stroma that usually first appears during adolescence and eventually causing severe visual impairment. In "Granular corneal dystrophy" multiple small white discrete irregular spots that resemble bread crumbs or snowflakes become apparent beneath Bowman zone in the superficial central corneal stroma. They initially appear within the first decade of life. Visual acuity is more or less normal. "Lattice dystrophy" starts as fine branching linear opacities in Bowman's layer in the central area and spreads to the preiphery. Recurrent corneal erosions may occur. The hallmark of "Schnyder corneal dystrophy" is the accumulation of crystals within the corneal stroma which cause corneal clouding typically in a ring-shaped fashion.

Posterior corneal dystrophies - "Fuchs corneal dystrophy" presents during the fifth or sixth decade of life. The characteristic clinical findings are excrescences on a thickened Descemet membrane (cornea guttae), generalized corneal edema and decreased visual acuity. In advanced cases, abnormalities are found in the all layers of the cornea. In "posterior polymorphous corneal dystrophy" small vesicles appear at the level of Descemet membrane. Most patients remain asymptomatic and corneal edema is usually absent. "Congenital hereditary endothelial corneal dystrophy" is characterized by a diffuse ground-glass appearance of both corneas and markedly thickened (2–3 times thicker than normal) corneas from birth or infancy.

Usually being asymptomatic, drusen are typically found during routine eye exams where the pupils have been dilated.

The diagnosis of Reis-Bücklers corneal dystrophy is based on the clinical presentation, rather than labs or imaging. Sometimes it is difficult to distinguish the disease from honeycomb dystrophy.

A practical application of AMD-associated genetic markers is in the prediction of progression of AMD from early stages of the disease to neovascularization.

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.

Imaging studies such as ultrasonography (US), Computerized Tomography (CT) and Magnetic Resonance Imaging (MRI) can aid diagnosis. On ultrasound, Coats' disease appears as a hyperechoic mass in the posterior vitreous without posterior acoustic shadowing; vitreous and subretinal hemorrhage may often be observed.

On CT, the globe appears hyperdense compared to normal vitreous due to the proteinaceous exudate, which may obliterate the vitreous space in advanced disease. The anterior margin of the subretinal exudate enhances with contrast. Since the retina is fixed posteriorly at the optic disc, this enhancement has a V-shaped configuration.

On MRI, the subretinal exudate shows high signal intensity on both T1- and T2-weighted images. The exudate may appear heterogeneous if hemorrhage or fibrosis is present. The subretinal space does not enhance with gadolinium contrast. Mild to moderate linear enhancement may be seen between the exudate and the remaining vitreous. The exudate shows a large peak at 1-1.6 ppm on proton MR spectroscopy.

Though there is no treatment for Cone dystrophy, certain supplements may help in delaying the progression of the disease.

The beta-carotenoids, lutein and zeaxanthin, have been evidenced to reduce the risk of developing age related macular degeneration (AMD), and may therefore provide similar benefits to Cone dystrophy sufferers.

Consuming omega-3 fatty acids (docosahexaenoic acid and eicosapentaenoic acid) has been correlated with a reduced progression of early AMD, and in conjunction with low glycemic index foods, with reduced progression of advanced AMD, and may therefore delay the progression of cone dystrophy.

A diagnosis of choroideremia can be made based on family history, symptoms, and the characteristic appearance of the fundus. However, choroideremia shares several clinical features with retinitis pigmentosa, a similar but broader group of retinal degenerative diseases, making a specific diagnosis difficult without genetic testing. Because of this choroideremia is often initially misdiagnosed as retinitis pigmentosa. A variety of different genetic testing techniques can be used to make a differential diagnosis.

Macular telangiectasia type 1 must be differentiated from secondary telangiectasis caused by retinal vascular diseases such as retinal venous occlusions, diabetic retinopathy, radiation retinopathy, sickle cell maculopathy, inflammatory retinopathy/Irvine–Gass syndrome, ocular ischemic syndrome/carotid artery obstruction, hypertensive retinopathy, polycythemia vera retinopathy, and localized retinal capillary hemangioma. In addition, Macular telangiectasia type 1 should be clearly differentiated from dilated perifoveal capillaries with evidence of vitreous cellular infiltration secondary to acquired inflammatory disease or tapetoretinal dystrophy. Less commonly, macular telangiectasis has been described in association with fascioscapulohumeral muscular dystrophy, incontinentia pigmenti, and familial exudative vitreoretinopathy with posterior pole involvement.

Macular telangiectasia type 2 is commonly under-diagnosed. The findings may appear very similar to diabetic retinopathy, and many cases ave been incorrectly ascribed to diabetic retinopathy or age-related macular degeneration. Recognition of this condition can save an affected patient from unnecessarily undergoing extensive medical testing and/or treatment. MacTel should be considered in cases of mild paramacular dot and blot hemorrhages and in cases of macular and paramacular RPE hyperplasia where no other cause can be identified.

Progressive vision loss in any dog in the absence of canine glaucoma or cataracts can be an indication of PRA. It usually starts with decreased vision at night, or nyctalopia. Other symptoms include dilated pupils and decreased pupillary light reflex. Fundoscopy to examine the retina will show shrinking of the blood vessels, decreased pigmentation of the nontapetal fundus, increased reflection from the tapetum due to thinning of the retina, and later in the disease a darkened, atrophied optic disc. Secondary cataract formation in the posterior portion of the lens can occur late in the disease. In these cases diagnosis of PRA may require electroretinography (ERG). For many breeds there are specific genetic tests of blood or buccal mucosa for PRA.

Absent a genetic test, animals of breeds susceptible to PRA can be cleared of the disease only by the passage of time—that is, by living past the age at which PRA symptoms are typically apparent in their breed. Breeds in which the PRA gene is recessive may still be carriers of the gene and pass it on to their offspring, however, even if they lack symptoms, and it is also possible for onset of the disease to be later than expected, making this an imperfect test at best.

Fluorescein angiography is usually performed for diagnosis and follow-up of patients with POHS.

Phototherapeutic keratectomy (PTK) done by an ophthalmologist can restore and preserve useful visual function for a significant period of time in patients with anterior corneal dystrophies including EBMD.

Retinal detachment can be examined by fundus photography or ophthalmoscopy. Fundus photography generally needs a considerably larger instrument than the ophthalmoscope, but has the advantage of availing the image to be examined by a specialist at another location and/or time, as well as providing photo documentation for future reference. Modern fundus photographs generally recreate considerably larger areas of the fundus than what can be seen at any one time with handheld ophthalmoscopes.

Ultrasound has diagnostic accuracy similar to that of examination by an ophthalmologist. The recent meta-analysis shows the diagnostic accuracy of emergency department (ED) ocular ultrasonography is high. The sensitivity and specificity ranged from 97% to 100% and 83% to 100%. The typical feature of retinal detachment when viewed on ultrasound is "flying angel sign". It shows the detached retina moving with a fixed point under the B mode, linear probe 10 MHz.

Grossly, retinal detachment and yellowish subretinal exudate containing cholesterol crystals are commonly seen.

Microscopically, the wall of retinal vessels may be thickened in some cases, while in other cases the wall may be thinned with irregular dilatation of the lumen. The subretinal exudate consists of cholesterol crystals, macrophages laden with cholesterol and pigment, erythrocytes, and hemosiderin. A granulomatous reaction, induced by the exudate, may be seen with the retina. Portions of the retina may develop gliosis as a response to injury.

Although MacTel is uncommon, its prevalence is probably higher than most physicians believe. The early findings are subtle, so the diagnosis is likely often missed by optometrists and general ophthalmologists. MacTel was detected in 0.1% of subjects in the Beaver Dam study population over age 45 years, but this is probably an underestimate because identification was made based only on color photographs.

No major new biomicroscopic features of MacTel have been identified since the early work of Gass and colleagues.

The advent of optical coherence tomography (OCT) has allowed better characterization of the nature of the inner and outer lamellar cavities. Loss of central masking seen on autofluorescence studies, apparently due to loss of luteal pigment, is now recognized as probably the earliest and most sensitive and specific MacTel abnormality.

The key fundus findings in macular telangiectasia type 2 involve retinal crystalline—fine, refractile deposits in the superficial retinal layers—may be seen within the affected area.a focal area of diminished retinal transparency (i.e. "greying") and/or small retinal hemorrhages just temporal to the fovea. Dilated capillaries may also be noted within this area, and while this is often difficult to visualize ophthalmoscopically, the abnormal capillary pattern is readily identifiable with fluorescein angiography.

Areas of focal RPE hyperplasia, i.e.pigment plaques, often develop in the paramacular region as a response to these abnormal vessels. Other signs of macular telangiectasia type 2 include right angle venules, representing an unusual alteration of the vasculature in the paramacular area, with vessels taking an abrupt turn toward the macula as if being dragged.

Diagnosis of MacTel type 2 may be aided by the use of advanced imaging techniques such as fluorescein angiography, fundus autofluorescence, and OCT. These can help to identify the abnormal vessels, pigment plaques, retinal crystals, foveal atrophy and intraretinal cavities associated with this disorder.

Fluorescein angiography (FA) is helpful in identifying the anomalous vasculature, particularly in the early stages of Type 2 disease. Formerly, FA was essential in making a definitive diagnosis. However, the diagnosis can be established with less invasive imaging techniques such as OCT and fundus autofluorescence. Some clinicians argue that FA testing may be unnecessary when a diagnosis is apparent via less invasive means.

The natural history of macular telangiectasia suggests a slowly progressive disorder. A retrospective series of 20 patients over 10 to 21 years showed deterioration of vision in more than 84% of eyes, either due to intra-retinal edema and serous retinal detachment (Type 1) or pigmented RPE scar formation or neovascularisation (Type 2).

CNV can be detected by using a type of perimetry called preferential hyperacuity perimetry. On the basis of fluorescein angiography, CNV may be described as classic or occult. Two other tests that help identify the condition include indocyanine green angiography and optical coherence tomography.

A minority of retinal detachments result from trauma, including blunt blows to the orbit, penetrating trauma, and concussions to the head. A retrospective Indian study of more than 500 cases of rhegmatogenous detachments found that 11% were due to trauma, and that gradual onset was the norm, with over 50% presenting more than one month after the inciting injury.

The diagnosis usually starts with a dilated examination of the retina, followed with confirmation by optical coherence tomography and fluorescein angiography. The angiography test will usually show one or more fluorescent spots with fluid leakage. In 10%-15% of the cases these will appear in a "classic" smoke stack shape. Differential diagnosis should be immediately performed to rule out retinal detachment, which is a medical emergency.

A clinical record should be taken to keep a timeline of the detachment. An Amsler grid can be useful in documenting the precise area of the visual field involved. The affected eye will sometimes exhibit a refractive spectacle prescription that is more far-sighted than the fellow eye due to the decreased focal length caused by the raising of the retina.

Indocyanine green angiography can be used to assess the health of the retina in the affected area which can be useful in making a treatment decision.

Vitelliform macular dystrophy causes a fatty yellow pigment (lipofuscin) to build up in cells underlying the macula. The retinal pigment epithelium also degenerates. Over time, the abnormal accumulation of this substance can damage the cells that are critical for clear central vision. As a result, people with this disorder often lose their central vision and may experience blurry or distorted vision, and loss is rarely symmetric. Scotomata appear, first with red light and then for green; finally, relative (or in more serious cases, absolute) scotomata occur with white light. Vitelliform macular dystrophy does not affect side (peripheral) vision or the ability to see at night.

Researchers have described two forms of vitelliform macular dystrophy with similar features. The early-onset form (known as Best disease) usually appears in childhood; however, the onset of symptoms and the severity of vision loss vary widely. The adult-onset form begins later, usually in middle age, and tends to cause relatively mild vision loss. The two forms of vitelliform macular dystrophy each have characteristic changes in the macula that can be detected during an eye examination.

Recurrence within a few years occurs in all patients following corneal transplantation. Soft contact lenses are effective in decreasing recurrences.

Early stages may be asymptomatic and may not require any intervention. Initial treatment may include hypertonic eyedrops and ointment to reduce the corneal edema and may offer symptomatic improvement prior to surgical intervention.

Suboptimal vision caused by corneal dystrophy usually requires surgical intervention in the form of corneal transplantation. Penetrating keratoplasty, a common type of corneal transplantation, is commonly performed for extensive corneal dystrophy.

With penetrating keratoplasty (corneal transplant), the long-term results are good to excellent. Recent surgical improvements have been made which have increased the success rate for this procedure. However, recurrence of the disease in the donor graft may happen. Superficial corneal dystrophies do not need a penetrating keratoplasty as the deeper corneal tissue is unaffected, therefore a lamellar keratoplasty may be used instead.

Phototherapeutic keratectomy (PTK) can be used to excise or ablate the abnormal corneal tissue. Patients with superficial corneal opacities are suitable candidates for a this procedure.

Treatment modalities currently under clinical investigation include cell therapy, gene therapy and oral therapies.

Regarding cell therapy, Advanced Cell Technology, now called Ocata Therapeutics, has completed Phase I/II multicenter clinical trial using retinal cells derived from human embryonic stem cells (hESCs) to treat patients with Stargardt. After treating and collecting data on 18 patients, Advanced Cell was given approval to test its stem cell therapy on patients with 20/100 vision. In October 2014, the results of the Phase I/II clinical trial were published in "the Lancet".

Research at the preclinical (animal) stage include a new compound that can remove lipofuscin from retinal pigment epithelial cells.