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Home > The Eye > Eye Diseases

Eye anatomy


Eye Diseases


Diabetic retinopathy

Pigmentary retinitis

Age-Related Retina Degeneration


Eye cancers


Floating bodies (myodesopsies)

Ocular infections: conjunctivitis, sty and others


The eye possesses its own lens called « crystalline lens » that functions as a camera lens. It allows focus of images on the retina. When it becomes cloudy, it affects near- and farsightedness and we call it a cataract. In most cases, ageing of the eye causes this cloudiness. However, other risk factors can lead to the development of a cataract:

  • Diabetes and other metabolic illnesses;
  • An eye wound;
  • Heredity;
  • Medications;
  • UV rays.

Diabetic retinopathy

Retina is a membrane covering the back of the eye and it captures images to forward to the brain. Diabetes can bring some problems to this part of the eye, such as a disease called diabetic retinopathy. In people suffering from this illness, abnormal blood vessels develop and fat or liquids can leak from them, causing a swelling of the retina. Small blood vessels may also spread on the retina and grow like the roots of a tree. If they break up, they may provoke hemorrhages.  

Pigmentary retinitis

View a testimony (in French):

Age-Related Retina Degeneration (ARRD)

The central part of the retina is called macula. It allows to read, write, threading a needle, and make any precision work. When macula is degenerated, the central vision (precision one) decreases and may even goes completely. However, peripheral vision is not affected and the disease does not lead to complete blindness. People suffering from ARRD are generally able to move by themselves, but they will have to stop driving their car.

ARRD mostly affects elderly and in North America, this disease is the main cause of central vision loss in people of more than 75 years old.

In the last 5 years, research regarding ARRD improved considerably. Breakthroughs have identified cigarette smoking and hereditary factors as 8 to 10 times increased risk to suffer from this disease.


The rounded shape of the eye is maintained by a light pressure from liquids secreted inside the eye. This is what we call intraocular pressure. If liquid outflow outside the eye is decreased, (for any reason) this pressure may increase and as a consequence, it may lead to optic nerve dysfunction (this nerve carries images from each eye to the brain).

Glaucoma is a disease leading to a damage of the optic nerve and a partial loss of vision fields (everything the eye can see on each side, on the bottom and above when focusing straight forward). Increase of intraocular pressure is often associated to glaucoma, but there are other risk factors who favor its development:

  • Family history of glaucoma;
  • Ageing;
  • Diabetes and other vascular diseases;
  • An important short-sightedness.

Eye cancers

There are two kinds of eye cancers, and their frequencies are fortunately rare: retinoblastoma and choroidian melanoma.

The first one is a malignant tumor of the retina that usually develops before the age of 5 years old. It affects one eye or both. This illness is genetic and affects one newborn out of between 15 000 and 20 000. The two most common symptoms are strabismus (wandering eye) and a white glint on the pupil (may be seen in a particular angle, under some lights).

Thanks to recent breakthroughs, this kind of cancer can be cured using laser, cryotherapy (use of cold to burn sick tissues), chemotherapy and/or radiotherapy, and patients can keep their eye. However, eye removal may still be necessary, especially if the cancer is in a late stage.

Choroidian melanoma is usually seen in adults (mean age when diagnosed is 56 years old). It is even less frequent than the retinoblastoma: there is one case for 100 000 people each year in France. This kind of melanoma mostly develops in pale eyes and sun exposure seems to be a risk factor (as for skin melanoma). More than one case may be seen in a family, or skin melanoma in addition to choroidian melanoma may develop in different members of the same family. However, heredity does not seem to be the cause. In opposition to retinoblastoma, it is very rare that both eyes are affected. The melanoma often spreads metastasis to the liver. The treatment is the same for both kinds of melanoma.


Amblyopia is a decrease of eyesight acquired in the first years of life. The vision of each eye is stimulated starting from birth and at each time the newborn opens his eyes.

In 4 to 7% of children, the vision path from one eye to the brain is not stimulated adequately. The most common cause of this problem is strabismus, which affects about 2% of population. The other main cause is when one eye sends a clear message to the brain while the other one is not used because it forwards a wrong image. It happens when one eye is more myopic (eye too long) or more hypermetropic (eye too short) than the other one.

Fortunately, amblyopia can be cured, usually using an eye patch to stimulate the visual development of the deficient eye only. If this treatment is started when the children is very young, it may be completely sorted out.

Floating bodies (myodesopsies)

A well-known phenomenon is called « floating bodies » and is characterized by opacities of different shapes and densities bathing in the fluids inside the eye (similar to wine red). Under some angles, the shadow of these floating bodies is superimposed to objects seen and the person feels like seeing small points, threads or even spiders.

If they are only few of them, there is no danger in having floating bodies in the eyes. However, if their quantity suddenly increases or if the person sees light flashes in addition to floating bodies, this person should quickly have an examination of the back of the eye by an ophthalmologist in order to detect more serious problems.


Ocular infections: conjunctivitis, sty and others

Ocular infections are frequent but usually safe and there are medications to cure them.


This infection is usually caused by a virus or bacteria, but it may also results from an allergy. It is characterized by an infection the conjunctiva, a translucent membrane covering the inside of eyelids and part of eyeballs.

Conjunctivitis is recognized by a redness of the eye, itching and thickened secretions that may make though eye opening when waking up. 

Usually, conjunctivitis subsides after few days and no serious consequences are observed. However, the infectious agent may affect the other eye.  Therefore, it is very important to use separated ophthalmic drops for each eye, to wash one's hands often and do not rub the infected eye, as you could contaminate your family circle.


Keratitis is an infection caused by a virus, bacteria or mold (in this latter case wearing of contact lenses may promote the disease). It is characterized by erosions or ulcerations of the cornea, which affects eyesight and makes it cloudy. The eye becomes red, painful and sensitive to light, as for conjunctivitis. However, healing time for a keratitis is longer and it is preferable to see an ophthalmologist for this kind of infection. This eye care professional will prescribe medications to accelerate recovery and by the way prevent cornea opacification. Otherwise, the affected person could have its eyesight decreased on a permanent basis.


This infection develops in the follicle of an eyelash and is seen as a small and swollen red ball. It is treated by applying an antibiotic ointment and warm and humid pack, which allows the stye to come to a head. Once it burst, it usually heals by itself.


There are glands in the eyes called « Meibomius glands » and these glands produce oily substances contained in tears. The chalazion is a cyst generally not painful and caused by an obstruction of these glands. It is treated with ophthalmic drops or antibiotic ointment and/or anti-inflammatory medications.


On eyelids, there are sebaceous glands producing a lubricating substance called sebum. When there is an increase in its production, a skin bacterium may cause an infection such as blepharitis, characterized by eyelid redness. Another symptom that may be seen is development of a scab, especially in the morning. There is usually no decrease in eyesight, but it causes a lot of discomfort to the affected eye.

References for the information presented in this section are in French (listed at the end of the page of the French content)