Vision, acute loss

Results in degeneration of retinal ganglion cells and their axons, causing an acute or sub-acute loss of central vision affects predominantly young adult males. Due to one of three point mutations in the ND4, NDl or ND6 subunit genes of complex I. 

The Vitrasert has proved to be safe and effective for treatment of CMV retinitis as an adjimct to continued systemic therapy. Although use of the Vitrasert is relatively safe, it is not free of complications. Adverse events can occur in 10% to 20% of patients and can result in significant loss of vision. Acute and long-term complications associated with the Vitrasert or its surgical procedure include retinal detachment, vitreous hemorrhage, and endophthalmitis. 

A 60-year-old smoker was treated with interferon alfa (100 MU/week for 2 months and 9 MU/week for 15 weeks) for cutaneous melanoma. Ocular examination was normal before treatment, but he developed acute loss of peripheral vision in his left eye after 23 weeks. Examination was consistent with anterior ischemic optic neuropathy, and there was optic disc edema, a pupillary defect, and circular visual field constriction in the left eye. There was renal artery constriction in both eyes. Despite treatment with aspirin, high-dose dexamethasone, heparin, and finally withdrawal of interferon alfa, loss of visual function progressed and affected both eyes. Ciclosporin was started, but he was considered to have irreversible loss of visual function. 

Severe irritant to eyes, skin, and respiratory tract can cause skin burn on contact causes visual disturbance and cloudy swelling of cornea with total or partial loss of vision acute inhalation and oral toxicity low symptoms irritation, nausea, and headache exposure to concentration >2000 ppm for 1-2 hr was lethal to most test subjects LD50 oral (mice) ... 

Patients with ocular hypertension or primary open-angle glaucoma typically have a slow, insidious loss of vision. This is contrasted by the course of acute primary angle-closure glaucoma which can lead to rapid vision loss that develops over hours to days. 

Acute, painless loss of vision Orbital cellulitis... 

A variety of disorders may lead to rapid, painless, monocular or binocular vision loss. This may include central retinal artery occlusion, acute narrow-angle glaucoma, trauma, or others. The differential diagnosis is complex and needs to be undertaken by an emergency department or ophthalmologist.9... 

Complex I deficiency due to mtDNA mutations (seven subunits of complex I are encoded by mtDNA) can be divided into encephalomyopathies and myopathies. The most important encephalomyopathy is Leber s hereditary optic neuropathy, characterized by acute or subacute loss of vision due to severe bilateral optic atrophy, with onset usually between 18 and 30 years and marked predominance in men. Three mutations (in ND1, ND4 and ND6)... 

In livestock, selenium has been found to be the cause of blind staggers and alkali disease. Blind staggers occurs as a result of acute ingestion of seleniferous plants and is characterized by impaired vision, depressed appetite, a tendency to wander in circles, paralysis, and death from respiratory failure. A more chronic syndrome described in horses and livestock is alkali disease, which also is associated with consumption of grains or plants containing selenium. The disease is characterized by lack of vitality, loss of appetite, emaciation, deformed hoofs, loss of hair, erosion of the joints of long bones, anemia, cirrhosis, and cardiac atrophy ... 

If steroid therapy fails or is contraindicated, irradiation of the posterior orbit, using well-collimated high-energy x-ray therapy, will frequently result in marked improvement of the acute process. Threatened loss of vision is an indication for surgical decompression of the orbit. Eyelid or eye muscle surgery may be necessary to correct residual problems after the acute process has subsided. 

The symptoms of acute exposure include headache, giddiness, nervousness, blurred vision, weakness, nausea, cramps, loss of muscle control or reflexes, convulsion, or coma. It has been suggested that impurities or additives may be associated with some cases of delayed polyneuropathy (damage to nerve cells) attributed to ingestion of large amounts of trichlorfon.87-90... 

During an acute imilateral attack, pupil testing reveals RAPD, because demyelinating disease can disrupt the impulses traveling within the pupillary fibers of the light reflex pathway. Color vision is reduced in most cases. Contrast sensitivity is reduced in cases of MS and may remain reduced after visual recovery occms. The ONTT reported that diffuse visual field loss occurred in 48.2% of eyes and that altitudinal field defects or other nerve fiber bimdle-type defects were present in 20.1% of eyes. Significantly, there was asymptomatic visual field involvement in the fellow eye in 68.8% of patients. 

Mild toxic reactions are characterized by slight reduction of visual acuity, flickering of vision, color vision decrease, impaired night vision, tinnitus, weakness, or confusion. In more severe cases, symptoms consist of sudden complete loss of vision, dizziness, and even deafness. Coma with circulatory collapse characterizes the most severe form of quinine toxicity. Patients may complain of impairment of night vision, but color vision is usually normal. The visual fields usually demonstrate concentric constriction. Improvement of the visual fields after the acute episode may require days or months, but the field loss may show no recovery and become permanent. 

In aluminium-overloaded dialysis patients, acute visual impairment can occur after only the first or second intravenous test dose of 40mg/kg deferoxamine (42-44). Visual symptoms are of retinal origin and include impairment of color vision, night bhndness, and reduced visual acuity serious and persistent visual loss can occur... 

The onset of visual loss can be sudden and dramatic, with color vision defects in the red-green or blue-yellow spectra, as well as variable field defects. In acute cases, disc edema is accompanied by sphnter hemorrhages. Retrobulbar neuritis with ethambutol can be predominantly axial, presenting with reduced visual acuity and central scotoma, or periaxial, with peripheral field defects. In non-acute tjrpes the fundi and discs appear normal (13). Visual defects can be unilateral or bilateral. 

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