What is it about ?
To see requires a complex collaboration between the eyes, the brain, and the nerves that connect the eyes to the brain. The eyes allow us to distinguish light, dark, colors and depth, but it is the brain that gives meaning to these elements so that we can recognize objects.
The causes of vision disturbances are very numerous. It may be an eye condition (bleeding in the eye, glaucomainflammation retinal detachment, myopia, hyperopia), a general disease (hypertension, diabetes…), increased pressure in the brain (tumor, hemorrhage…), a blood supply disorder (thrombosis of the artery of the eye), ingestion of a toxic substance (methanol, quinine …) or a hereditary disease.
If your visual disturbance appears quickly and you do not know the cause, see your doctor or an ophthalmologist urgently. The faster the vision loss, the faster you have to react.
Slowly developing symptoms may also sometimes require an ophthalmologist urgently (for example, with a wet form of age-related macular degeneration).
The most urgent situations are those where it is possible to save the vision by rapid treatment.
How to recognize it?
The reduction in vision can be sudden or slow, brief or prolonged and with or without pain, distortion of the image, disturbances of the field of vision or general symptoms such as headache, nausea, fever …
Diseases that require urgent treatment
It is important to quickly recognize problems that require urgent treatment. These are usually diseases that affect only one eye:
- Sudden, painless vision loss in one eye may be due to a blockage (thrombosis) of a major blood vessel in the eye.
- The appearance of a shadow or “veil” that takes up more and more space in the field of view of one eye may indicate a retinal detachment.
- Suddenly reduced vision in one eye combined with pain in that eye and nausea and headache may indicate poor drainage from the eye (acute glaucoma).
Common causes
- In case of cataract, the lens of the eye becomes opaque. First, it turns yellow-green, then red-brown. White flakes may appear. The view then becomes blurry, as if there is fog. The images are sometimes distorted. Often there is also double vision and light sensitivity (the person cannot stand bright light). People with cataracts become myopic (loss of distance vision). At the last stage, they see only light and dark, but no longer have an image.
- Near vision is normal with myopia, but the person cannot see well from a distance. To see better from a distance, the person narrows their eyes. Nearsighted children find it difficult to read what is written on the board.
- In the case of hyperopia, the reverse is true: the person sees well from a distance, but they cannot see well up close. Since near vision requires effort, the eyes are tired, especially at night. Headaches can occur, sometimes with the feeling of a bar above the eyes.
- In astigmatism, the eye is not perfectly round, but slightly distorted like a rugby ball. As a result, the person sees poorly, both far and near.
Other causes
- Increased pressure in the skull : sudden and transient loss of vision without pain for several seconds. Double vision, dizziness, headache, nausea and vomiting (especially in the morning) can also occur transiently. Increased pressure inside the skull may be due to a brain tumor, brain hemorrhage, or inflammation of the brain.
- Disorder of the blood supply to the optic nerve or retina : sudden and painless loss of vision.
- Rheumatic disease, a muscular rheumatism : sudden loss of vision with headache or general symptoms (cramps in the jaw muscles, sore temples, fever, weight loss and muscle pain for several weeks or months).
- Ingestion of toxic substances such as methanol (a highly toxic type of alcohol) or quinine (medicine for malaria (malaria)): reduced vision or even blindness.
- Clogged eye vein (thrombosis of the eye): Vision deteriorates on one side only, and this is most noticeable in the morning.
- Bleeding in eye fluid (glazed): a hazy screen suddenly appears in the field of vision; it moves with the movements of the head or the eyes.
- Glaucoma acute: decrease in vision within a few hours, with headache, severe eye pain, nausea and vomiting. In this disease, eye fluid can no longer be drained normally. As a result, the pressure in the eye increases, which leads to the death of the nerve fibers in the eye and the loss of part of the field of vision.
- Eye infection (due to viruses, bacteria or parasites): redness and mild pain in the eye with decreased vision within a few days. Sensitivity to light (photophobia) and swelling of the eyelid may also occur.
- Retinal detachment : decrease in vision for days and appearance of a shadow in the field of vision. This can happen spontaneously or after eye damage or surgery on the eye.
- Inflammation of the optic nerve due to an infection or neurological disease, such as multiple sclerosis (MS) : A decrease in vision for a few days with a dull ache, which becomes more intense when moving the eyes, is often a sign of visual disturbances of central origin. The person then no longer sees the image in the center of the field of vision, and he can sometimes only distinguish the movements of the hand. Color vision is also affected (reduced sensitivity to red and contrasts).
- Chronic glaucoma : deterioration of sight over months or years, accompanied by progressive disturbances in the field of vision. In the terminal stage, the person can go blind.
- Inherited diseases of the retina (such as retinitis pigmentosa) are accompanied by glare in the field of vision, sensitivity to light, night blindness, and a progressive narrowing of the field of vision.
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