Loss of vision

The fovea is the only part of the eye with 6/6 vision. When it is damaged, vision loss occurs in most cases.

• In such cases, the patient always waits for an answer to the question: “Am I blind?”
• Each such patient requires the attention of a specialist, unless, of course, the cause of vision loss is migraine.
• Always determine the ESR in such cases, since this way it is possible to identify temporal arteritis, and this can save the vision of the other eye.

Intermittent blindness (amaurosis fugax) is a temporary loss of vision. In such cases, the patient says that it is as if a curtain has fallen before his eyes. In temporal arteritis, this sometimes precedes irreversible loss of vision. The cause may also be an embolism of the corresponding artery, so that a correct diagnosis can save vision.

The main causes of vision loss:

Ischemic optic neuropathy. If blood flow in the ciliary arteries is disrupted (occlusion due to inflammatory infiltration or arteriosclerosis), then damage to the optic nerve occurs. Fundoscopy reveals a pale and swollen optic disc.

Temporal arteritis (giant arteritis). It is important to recognize this disease because there is a high risk of losing vision in the other eye if treatment is not started promptly. The condition may be accompanied by general weakness, sudden transient pain when chewing (mandibular intermittent claudication) and sensitivity when palpating the scalp in the temporal arteries (when checking their pulsation). This disease is often combined with rheumatic polymyalgia. ESR may exceed 40 mm/h, which allows us to suspect this disease; a biopsy of the temporal artery may also yield a false-negative result if a section of an unaffected artery is included in the biopsy. In such cases, prednisolone should be quickly prescribed at 80 mg/day orally. A gradual reduction in the steroid dose as the clinical picture stabilizes and the ESR decreases may last for more than a year.

Arteriosclerotic ischemic optic neuropathy. Hypertension, lipid metabolism disorders and diabetes mellitus may predispose to this disease, and it can be observed even in relatively young people. Appropriate treatment will help preserve vision in the other eye.

Occlusion of the central retinal artery. In this case, the eye does not perceive light and an afferent pupillary defect is noted. The retina is very pale (almost white), but a cherry-red dot can be seen in the macula. The optic disc is swollen. Occlusion of the artery usually occurs due to a thrombus or embolus (in such cases, it is necessary to auscultate the carotid arteries in order to detect noise). I can try to press hard on the eyeball in order to displace what has blocked the artery, but if the occlusion continues for more than an hour, then atrophy of the optic nerve occurs with subsequent blindness. If one branch of the retinal artery is occluded, then, accordingly, retinal and visual changes will affect only that part of the retina where the blood supply is disrupted.

Vitreous hemorrhage. This is a particularly common cause of vision loss in patients with diabetes mellitus, who develop new vessels. Such hemorrhage can also occur with hemorrhagic diathesis, with retinal detachment. If the hemorrhage is large enough and vision is lost, the red reflex disappears, and the retina cannot be seen. Vitreous hemorrhages undergo spontaneous resorption, so treatment for the hemorrhage itself is expectant, but in general it should be aimed at the causes that caused it (for example, photocoagulation of newly formed vessels). Small blood extravasates lead to the formation of floating bodies in the vitreous body, which may not significantly impair vision.

Central retinal vein occlusion. The incidence of this disease increases with age. It is more common than central retinal artery occlusion. Predisposing factors include chronic simple glaucoma, arteriosclerosis, hypertension and polycythemia. If the entire central retinal vein is thrombosed, sudden loss of vision occurs and its acuity decreases to "counting fingers". The fundus of the eye has the appearance of "sunset before a storm", it is hyperemic, the veins are sharply tortuous, with hemorrhages along their course. The long-term prognosis is variable, improvement is possible in periods from 6 months to 1 year, mainly peripheral vision improves, while macular vision remains impaired. Formation of new vessels may begin with a high risk of hemorrhage into the eye (in 10-15% of cases). If only the branches of the central vein are affected, changes in the fundus are traced only in the corresponding quadrant. There is no specific treatment.

Loss of vision in one eye may occur due to retinal detachment, acute glaucoma (painful), and migraine. Stroke patients sometimes complain of blindness in one eye, but visual field examination in such cases usually reveals homonymous hemianopsia. Sudden blindness in both eyes is extremely rare, for example, in cytomegalovirus infection in AIDS patients.

Subacute vision loss

Optic neuritis is an inflammation of the optic nerve. Unilateral loss of visual acuity occurs for hours or days. Color perception is impaired: red appears less red; eye movements may be painful. An afferent defect is found in the pupil. The optic disc may be edematous (papillitis), unless, of course, the inflammation is localized more centrally (then we speak of retrobulbar neuritis). There is virtually no treatment, but young people usually recover, although some of these patients later develop multiple sclerosis.

Gradual loss of vision

Possible causes of gradual vision loss in one eye may be choroiditis, "spreading" inferior retinal detachment, or choroidal melanoma. If vision loss occurs in both eyes (usually asymmetrical), then its causes are often cataracts, chronic glaucoma, diabetic and hypertensive retinopathy, senile macular degeneration, or optic nerve atrophy.

Choroiditis (chorioretinitis). The choroidea is part of the vascular tunic of the eyeball. (In addition to the choroid, the choroid also includes the iris and ciliary body.) Therefore, inflammatory processes affecting the uvea also affect the choroid. The retina can be invaded by microorganisms, which usually causes granulosmatous reactions (which must be differentiated from retinoblastoma). Toxoplasmosis and toxocariasis are currently more common than tuberculosis. Sarcoidosis can also be the cause of such a reaction. Examination of the patient - chest X-ray, Mantoux test, serological tests, Kveim test. In the acute phase, vision may be blurred, unclear; Raised whitish-gray spots may be visible on the retina, the vitreous may be clouded, and cells may be found in the anterior chamber of the eye. Later, a chorioretinal scar (a white spot with pigmentation around it) appears. This is not accompanied by any symptoms, unless, of course, the area of the macula is involved in the process. Treatment is etiological.

Malignant melanoma of the choroid. This is the most common malignant tumor of the eye. Initially, gray-black spots appear on the fundus, and as they grow, retinal detachment occurs. The tumor spreads hematogenously or through local invasion of the orbit. Treatment consists of enucleation of the affected eyeball, but in some cases local treatment is also possible.

Senile macular degeneration. This is the most common cause of registered blindness in the UK. Senile macular degeneration begins in older people who complain of deterioration of central vision. There is a loss of visual acuity, but the visual fields are not affected. The optic disc is normal but there is pigment, minor exudate and haemorrhage in the macula. In some cases the macula is swollen and raised by a large amount of exudate - this is called discoid degeneration. In most cases there is no effective treatment. However, laser therapy is sometimes used. The use of adjuvant measures can bring symptomatic relief.

Tobacco amblyopia. This is an atrophy of the optic nerve due to smoking, or rather, cyanide poisoning. This causes a gradual loss of central vision. An early and constant symptom is the loss of the ability to distinguish between red and green colors.

Optic nerve atrophy. The optic disc appears pale, but the degree of paleness does not always correspond to vision loss. Optic nerve atrophy may be secondary to increased intraocular pressure (glaucoma), retinal damage (choroiditis, retinitis pigmentosa, cerebromacular degeneration), but it may also be associated with ischemia (retinal artery occlusion). In addition to tobacco, optic nerve atrophy may be caused by toxic substances such as methanol, lead, arsenic, quinine, and carbon bisulfide. Other causes include Leber's optic atrophy, multiple sclerosis, syphilis, external pressure on the nerve (intraorbital or intracranial tumors, Paget's disease localized in the skull).