There are several inconveniences that can affect vision : metamorphopsia, photophobia, scotomas, night blindness, visual hallucinations, occasional loss of vision, mirages, altered perception of colours, visual fatigue or “dryness” syndromes.
Type of publication:Good practises
Date of publication:12/24/2012
Publishing organization:Centich, France
What are metamorphopsia? What causes them and how to treat them?
It is a distorted perception of lines and objects.
From close up, lines of text seem wavy and distorted.
From further away, distortion of trees or white traffic lines is common.
Causes are diverse. The professional opinion of an ophthalmologist is necessary in order to diagnose and cure them.
What is photophobia? What causes it and how to treat it?
It is the need to avoid light due to the inconveniences and/or pain it results in. The affected people hide in the shade behind tinted glass. It can cause a blepharospasm: the eyelids are clenched, held together to protect the eyes from light.
Photophobia can be caused by a neurological or ocular condition. In order to determine the cause, a medical examination is necessary. In cases of photophobia, it is the cause which must first be treated.
What are scotomas? What causes them and how to treat them?
They are the more or less intense blurring of one's field of vision.
There are several kinds of scotoma:
Scintillating scotomas, which are bright moving patches
Central scotomas, which appear in the centre of the field of vision, or peripheral ring scotomas that appear anywhere else in the field of vision.
They can be caused by:
floating bodies on the vitreous membrane that are tiny patches or filaments that float around and that, when trying to observe them directly, either disappear, either stay in place,
a maculopathy. It is a lesion of the centre of the retina, observed during age-related macular degeneration, producing a patch at the centre of the field of vision which prevents reading and perception of details.
A retinal detachment that causes the perception of a peripheral dark haze progressing towards the centre, preceded by flashes and sparkles.
In cases of scotoma, it is the cause which is treated.
What is night blindness? What causes it and how to treat it?
It is a disorder of the retinal adaptation to darkness causing difficulties to move in low light conditions.
It concerns mainly hereditary diseases such as retinitis pigmentosa but is also observed in acquired conditions such as lack of vitamin A.
There is no treatment.
What are visual hallucinations? What causes them and how to treat them?
They are the perception of non-real objects. They can be “basic” images of luminous dots but also more elaborate images of people or objects.
They are common for people that suffer from migraines (scintillating scotomas), epilepsy (where “déjà vu” feelings can precede the outbreaks), or during intense reactions to drug or alcohol-induced intoxications.
In cases of visual hallucinations, it is the cause which is treated.
What is an occasional loss of vision? What are the causes and how to treat it?
It is the spontaneously regressive total or partial loss of vision observed in cases of retinal migraine. They are most often caused by vascular problems or lack of blood flow to the brain, and require a general and neurological examination to determine the most appropriate treatment.
What are mirages?
It is a phenomenon linked to light reflection that occurs when a cool air stream flows over a warmer one. It is then possible to observe the distorted image of a real object in the distance.
What is an altered perception of colours?
- Hereditary alterations in perception of colours.
They concern 8% of men against 0.4% of women.
We distinguish three types of alteration:
The protanomaly, which prevents the subject from perceiving red
The deutanomaly, which prevents the subject from perceiving green,
And tritanomaly which prevents the subject from perceiving all colours.
The discomfort is insignificant on a personal level but can be socially restrictive and result in vocational contraindications.
- Acquired alterations in perception of colours.
They can be the result of conditions of the retina or the optic nerve, of general pathologies such as diabetes or of drug induced intoxication from ethambutol or synthetic antimalarials for instance.
What is visual fatigue? What are the causes and how to treat it?
They are experienced at end of a working day, week or term and are characterized by their spontaneous return to normal after a period of rest.
People feel tingling and eye burns.
To prevent this fatigue, it is necessary to observe periodical visual breaks especially when working on a computer all day.
What are “dryness” syndromes? What causes them and how to treat them?
They appear around the age of fifty and are characterised by a pain when opening the eyes in the morning with tingling and eye burns throughout the day.
There are two main causes:
Causes linked to the use of drugs: beta blockers, anti-psychotics, atropine.
General cause: the Sjögren syndrome.
The subject has a “foreign body” sensation, endures itching and dry eyes with, at maximum, frothy edges of eyelids.
It can be found in rheumatoid arthritis, periarteritis nodosa and lupus erythematosus. The treatment is that of its cause.