A thorough history is essential and should cover family history, diet; drug/toxin exposure social history, including tobacco and alcohol use; and occupational background, with details on whether similar cases exist among coworkers. Treatment of any chronic disease such as pernicious anemia should always be elucidated.

In most cases of nutritional/toxic optic neuropathy, the diagnosis may be obtained via detailed medical history and eye examination. Additionally, supplementary neurological imaging studies, such as MRI or enhanced CT, may be performed if the cause remains unclear.

When the details of the examination and history indicate a familial history of similar ocular or systemic disease, whether or not there is evidence of toxic or nutritional causes for disease, certain genetic tests may be required. Because there are several congenital causes of mitochondrial dysfunction, the patients history, examination, and radiological studies must be examined in order to determine the specific genetic tests required. For example, 90% of cases of Leber’s Hereditary Optic Neuropathy (LHON) are associated with three common mtDNA point mutations (m.3460G>A/MT-ND1, m.11778G>A/MT-ND4, m.14484T>C/MT-ND6) while a wider range of mtDNA mutations (MT-ND1, MT-ND5, MT-ND6; http://www.mitomap.org/) have been associated with overlapping phenotypes of LHON, MELAS, and Leigh syndrome.

The United States Preventive Services Task Force as of 2013 states there is insufficient evidence to recommend for or against screening for glaucoma. Therefore, there is no national screening program in the US. Screening, however, is recommended starting at age 40 by the American Academy of Ophthalmology.

There is a glaucoma screening program in the UK. Those at risk are advised to have a dilated eye examination at least once a year.

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.

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.

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).

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.

The diagnosis of childhood blindness is done via methods to ascertain the degree of visual impairment in the affected child doing so via "dilating eye drops" and the proceeding eye exam.

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.

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.

Braille is a universal way to learn how to read and write, for the blind. A refreshable braille display is an assistive learning device that can help such children in school. Schools for the blind are a form of management, however the limitations of using studies done in such schools has been recognized. Children that are enrolled presently, usually, had developed blindness 5 or more years prior to enrollment, consequently not reflecting current possible causes. About 66% of children with visual impairment also have one other disability (comorbidity), be it, intellectual disabilities, cerebral palsy, or hearing loss. Eye care/screening for children within primary health care is important as catching ocular disease issues can lead to better outcomes.

Those diseases understood as congenital in origin could either be specific to the ocular organ system (LHON, DOA) or syndromic (MELAS, Multiple Sclerosis). It is estimated that these inherited optic neuropathies in the aggregate affect 1 in 10,000

Of the acquired category, disease falls into further etiological distinction as arising from toxic (drugs or chemicals) or nutritional/metabolic (vitamin deficiency/diabetes) insult. It is worth mentioning that under-nutrition and toxic insult can occur simultaneously, so a third category may be understood as having a combined or mixed etiology. We will refer to this as Toxic/Nutritional Optic Neuropathy, whereby nutritional deficiencies and toxic/metabolic insults are the simultaneous culprits of visual loss associated with damage and disruption of the RGC and optic nerve mitochondria.

Screening for glaucoma is usually performed as part of a standard eye examination performed by optometrists and ophthalmologists. Testing for glaucoma should include measurements of the intraocular pressure via tonometry, anterior chamber angle examination or gonioscopy, and examination of the optic nerve to look for any visible damage to it, or change in the cup-to-disc ratio and also rim appearance and vascular change. A formal visual field test should be performed. The retinal nerve fiber layer can be assessed with imaging techniques such as optical coherence tomography, scanning laser polarimetry, and/or scanning laser ophthalmoscopy (Heidelberg retinal tomogram).

Owing to the sensitivity of all methods of tonometry to corneal thickness, methods such as Goldmann tonometry should be augmented with pachymetry to measure the central corneal thickness (CCT). A thicker-than-average cornea can result in a pressure reading higher than the 'true' pressure whereas a thinner-than-average cornea can produce a pressure reading lower than the 'true' pressure.

Because pressure measurement error can be caused by more than just CCT (i.e., corneal hydration, elastic properties, etc.), it is impossible to 'adjust' pressure measurements based only on CCT measurements. The frequency doubling illusion can also be used to detect glaucoma with the use of a frequency doubling technology perimeter.

Examination for glaucoma also could be assessed with more attention given to sex, race, history of drug use, refraction, inheritance and family history.

Glaucoma has been classified into specific types:

Retinopathy is diagnosed by an ophthalmologist or an optometrist during eye examination. Stereoscopic fundus photography is the gold standard for the diagnosis of retinopathy. Dilated fundoscopy, or direct visualization of the fundus, has been shown to be effective as well.

Diabetic retinopathy is diagnosed entirely by recognizing abnormalities on retinal images taken by fundoscopy. Color fundus photography is mainly used for staging the disease. Fluorescein angiography is used to assess the extent of retinopathy that aids in treatment plan development. Optical coherence tomography (OCT) is used to determine the severity of edema and treatment response.

Because fundoscopic images are the main sources for diagnosis of diabetic retinopathy, manually analyzing those images can be time-consuming and unreliable, as the ability of detecting abnormalities varies by years of experience. Therefore, scientists have explored developing computer-aided diagnosis approaches to automate the process, which involves extracting information about the blood vessels and any abnormal patterns from the rest of the fundoscopic image and analyzing them.

Patients and their primary care physicians must be made fully aware of the ophthalmic risks and the need for regular screening examinations to detect retinal toxicity at an early stage.

Baseline evaluation for patients beginning treatment with a chloroquine derivative should include a complete eye examination by an eye care professional, retinal photography for follow-up comparisons, and Visual field testing with a white pattern. Central visual field assessment should test the central 10° of vision with a white test target (such as Humphrey 10-2 program).

In patients at risk or those with unclear presentation, optical coherence tomography (loss of IS/OS junctions), fundus autofluorescence (focal hyper or hypoautofluorescence), and multifocal electroretinography (paracentral depressions) may be obtained.

Profound abnormalities detected with visual field and multifocal electroretinography testing can be observed in the presence of a normal retinal appearance. Retinal examinations are advised for documentation, but visible bull's-eye maculopathy is a late change, and the goal of screening is to recognize toxicity at an earlier stage. Annual screening should begin after 5 years (or sooner if there are unusual risk factors).

Retinal degeneration is the deterioration of the retina caused by the progressive and eventual death of the cells of the retina. There are several reasons for retinal degeneration, including artery or vein occlusion, diabetic retinopathy, R.L.F./R.O.P. (retrolental fibroplasia/ retinopathy of prematurity), or disease (usually hereditary). These may present in many different ways such as impaired vision, night blindness, retinal detachment, light sensitivity, tunnel vision, and loss of peripheral vision to total loss of vision. Of the retinal degenerative diseases retinitis pigmentosa (RP) is a very important example.

Inherited retinal degenerative disorders in humans exhibit genetic and phenotypic heterogeneity in their underlying causes and clinical outcomes*. These retinopathies affect approximately one in 2000 individuals worldwide. A wide variety of causes have been attributed to retinal degeneration, such as disruption of genes that are involved in phototransduction, biosynthesis and folding of the rhodopsin molecule, and the structural support of the retina. Mutations in the rhodopsin gene account for 25% to 30% (30% to 40% according to) of all cases of autosomal dominant retinitis pigmentosa (adRP) in North America. There are many mechanisms of retinal degeneration attributed to rhodopsin mutations or mutations that involve or affect the function of rhodopsin. One mechanism of retinal degeneration is rhodopsin overexpression. Another mechanism, whereby a mutation caused a truncated rhodopsin, was found to affect rod function and increased the rate of photoreceptor degeneration.

- *For example, a single peripherin/RDS splice site mutation was identified as the cause of retinopathy in eight families; the phenotype in these families ranged from retinitis pigmentosa to macular degeneration.

Cessation of the drug at the first sign of toxicity is recommended. No treatment exists as yet for this disorder, so it is imperative that patients and their ophthalmologists be aware of the best practices for minimizing toxic damage.

It is important to differentiate CPEO from other pathologies that may cause an ophthalmoplegia. There are specific therapies used for these pathologies.

CPEO is diagnosed via muscle biopsy. On examination of muscle fibers stained with Gömöri trichrome stain, one can see an accumulation of enlarged mitochondria. This produces a dark red staining of the muscle fibers given the name “ragged red fibers”. While ragged red fibers are seen in normal aging, amounts in excess of normal aging give a diagnosis of a mitochondrial myopathy.

Polymerase Chain Reaction (PCR), from a sample of blood or muscle tissue can determine a mutation of the mtDNA.

Elevated acetylcholine receptor antibody level which is typically seen in myasthenia gravis has been seen in certain patients of mitochondrial associated ophthalmoplegia.

It is important to have a dilated eye exam to determine if there is pigmentary retinopathy that may signify Kearns-Sayre syndrome which is associated with cardiac abnormalities.

MRI may be helpful in the diagnosis, in one study volumes of medial rectus, lateral rectus, and inferior rectus muscles in CPEO were not smaller than normal (in contrast to the profound atrophy typical of neurogenic paralysis). Although volumes of the superior rectus muscle-levator complex and superior oblique were significantly reduced.

Generally speaking, people diagnosed with photic retinopathy recover visual acuity completely within two months, though more severe cases may take longer, or not see complete recovery at all.

Treatment is based

on the stage of the disease. Stage 1 does not

require treatment and

should be observed. 4

Neovascularization

(stage 2) responds well

to laser ablation or

cryotherapy.2,4 Eyes

with retinal detachments (stages

3 through 5) require surgery, with

earlier stages requiring scleral

buckles and later stages ultimately

needing vitrectomy. 2,4

More recently, the efficacy of

anti-VEGF intravitreal injections

has been studied. In one study,

these injections, as an in adjunct

with laser, helped early stages

achieve stabilization, but further

investigation is needed.6

The prognosis for CSR is generally excellent. Whilst immediate vision loss may be as poor as 20/200 in the affected eye, clinically over 90% of patients regain 20/30 vision or better within 6 months.

Once the fluid has resolved, by itself or through treatment, visual acuity should continue to improve and distortion should reduce as the eye heals. However, some visual abnormalities can remain even if visual acuity is measured at 20/20, and lasting problems include decreased night vision, reduced color discrimination, and localized distortion caused by scarring of the sub-retinal layers.

Complications include subretinal neovascularization and pigment epithelial detachment.

The disease can re-occur causing progressive vision loss. There is also a chronic form, titled as type II central serous retinopathy, which occurs in approximately 5% of cases. This exhibits diffuse rather than focalized abnormality of the pigment epithelium, producing a persistent subretinal fluid. The serous fluid in these cases tends to be shallow rather than dome shaped. Prognosis for this condition is less favorable and continued clinical consultation is advised.

A neuro-ophthalmologist is usually involved in the diagnosis and management of KSS. An individual should be suspected of having KSS based upon clinical exam findings. Suspicion for myopathies should be increased in patients whose ophthalmoplegia does not match a particular set of cranial nerve palsies (oculomotor nerve palsy, fourth nerve palsy, sixth nerve palsy). Initially, imaging studies are often performed to rule out more common pathologies. Diagnosis may be confirmed with muscle biopsy, and may be supplemented with PCR determination of mtDNA mutations.

FEVR is, as its name suggests,

familial and can be inherited in an

autosomal dominant, autosomal

recessive or X-linked recessive pattern.1-3 It is caused by mutations in

FZD4, LRP5, TSPAN12 and NDP

genes, which impact the wingless/

integrated (Wnt) receptor signaling

pathway. 3 Disruption of this path

way leads to abnormalities of vascu-

lar growth in the peripheral retina. 2,3

It is typically bilateral, but asymmetric, with varying degrees of

progression over the individual’s

lifetime. Age of onset varies, and

visual outcome can be strongly

influenced by this factor. Patients

with onset before age three have a

more guarded long-term prognosis

whereas those with later onset are

more likely to have asymmetric

presentation with deterioration of

vision in one eye only. 2-3 However,

because FEVR is a lifelong disease,

these patients are at risk even as

adults.2 Ocular findings and useful

vision typically remain stable if the

patient does not have deterioration

before age 20.2,4 Due to the variability and unpredictability of the

disease course, patients with FEVR

should be followed throughout

their lifetime.

Clinical presentation can vary

greatly. In mild variations, patients

may experience peripheral vascular

changes, such as peripheral avascular zone, vitreoretinal adhesions,

arteriovenous anastomoses and a

V-shaped area of retinochoroidal

degeneration. 4 Severe forms may

present with neovascularization,

subretinal and intraretinal hemorrhages and exudation. 4 Neovascularization is a poor prognostic

indicator and can lead to retinal

folds, macular ectopia and tractional retinal detachment. 2,4 Widefield FA has been crucial in

helping to understand this disease,

as well as helping to confirm the

diagnosis. An abrupt cessation

of the retinal capillary network

in a scalloped edge posterior to

fibrovascular proliferations can

be made using FA.2,3,5 Patients can

also show delayed transit filling on

FA as well as delayed/patchy choroidal filling, bulbous vascular terminals, capillary dropout, venous/venous shunting and abnormal

branching patterns. 2,3,5 The staging of FEVR is similar

to that of retinopathy of prematurity. The first two stages involve an

avascular retinal periphery with or

without extraretinal vascularization (stage 1 and 2, respectively). 4 Stages three through five delineate

levels of retinal detachment; stage 3

is subtotal without foveal involvement, stage 4 is subtotal with foveal

involvement and stage 5 is a total

detachment, open or closed funnel.4

Because there was neovascularization in the absence of retinal detachment, our patient was

considered to have

stage 2.

Photic retinopathy generally goes away on its own over time, but there is no specific treatment known to be reliable for speeding recovery. One path sometimes attempted, which has unclear results, is to treat the initial macular edema with corticosteroids.

It is not necessary to biopsy an ocular muscle to demonstrate histopathologic abnormalities. Cross-section of muscle fibers stained with Gömöri trichrome stain is viewed using light microscopy. In muscle fibers containing high ratios of the mutated mitochondria, there is a higher concentration of mitochondria. This gives these fibers a darker red color, causing the overall appearance of the biopsy to be described as "ragged red fibers. Abnormalities may also be demonstrated in muscle biopsy samples using other histochemical studies such as mitochondrial enzyme stains, by electron microscopy, biochemical analyses of the muscle tissue (ie electron transport chain enzyme activities), and by analysis of muscle mitochondrial DNA. "