Structural defects of the eye in which the light rays from a viewed object do not meet in a single focal point, resulting in blurred images being sent to the brain. An astigmatic cornea is not perfectly rounded like a basketball but has an irregular shape more like the side of a football
Blepharitis is an inflamation that usually affects both eyes along the edges of the eyelids. It commonly occurs when tiny oil glands near the base of the eyelashes become clogged, causing irritation and redness
There are 2 clinical forms that can be desiphered:
– Prior damages on the skin side of the palpebral edge (free edge and eyelashes) such as staphylococcal seborrheic blepharitis
– Posterior damage, also called “meibomian dysfunction”, concerning the mucous side of the palpebral edge. Meibomian dysfunction is characterized by a meibum that is too viscous to naturally exit the meibomian glands when blinking. The obstruction of the orifices of these glands disrupts the lipid layer of the tear film which leads to dry eyes by hyperevaporation of the tears.
Symptoms are common for both clinical forms – redness, swollen palpebral edge, secretions and crusts. In first type damage to the eyelashes is predominant (short, brittle eyelashes or even loss of eyelashes). In latter one, thick secretions, dry eyes and often recurrent chalazia can be observed in children.
Partial or total clouding of the lens that interferes with the passage of light. In most cases cataracts are related to age.
Age-related cataracts are the leading cause of blindness worldwide (48%), being resposible for 18 million people. (*Data by WHO)
It affects more than 60% of people over 85 years old in France.
State of a person deprived of the vision.
The mucous membrane that covers the front of the eye and lines the inside of the eyelids
Inflammation of the conjunctiva of allergic, viral or bacterial origin. It is manifested by itching, redness, tearing and a feeling of sand in the eye.
Thin and transparent membrane on the surface of the eye covering the iris and pupil. It constitutes the first lens of the ocular optical system.
Intermediate layer of the tear film consisting of water (98%), mucins and anti-inflammatory proteins. It is secreted by the lacrimal glands and provides defense and nutrition functions for the ocular surface.
Surface layer of the tear film consisting of meibum and phospholipids. Essentially secreted by the Meibomian glands, it limits the evaporation of tears and acts as a lubricant between the cornea and the eyelids.
Basal layer of the tear film made up of mucins that make the ocular surface hydrophilic. It allows the tear film to adhere to the ocular surface and contributes to its stability.
Internal lens of the eye which ensures the sharpness of the images by modifying its curvature. If the lens loses its elasticity, it is responsible for presbyopia and if it becomes cloudy, it is responsible for cataracts.
Eye disease which may appear with age. It affects the center of the retina, called the macula, and causes loss of central vision without affecting peripheral vision.
AMD is the third leading cause of visual impairment in the world and accounts for 8.7% of the causes of blindness. It is the leading cause of visual impairment in industrialized countries.
The main risk factor is age. Other possible risk factors are smoking, genetic influence, degree of pigmentation (greater risk in case of clear iris), high blood pressure, ultraviolet rays and dietary imbalance. (* Source: WHO)
The tear film provides nutritional functions as well as mechanical, chemical and anti-infectious protection of the ocular surface.
It is made up of 3 layers:
– The mucinic layer
– The aqueous layer
– The lipid layer
The entire lipid layer is essential: its deterioration leads to overevaporation of tears and eventually to dry eye.
The Meibomian glands were named by Meibom H. who first described them in 1666. They are located on the free edge of the eyelids and number 30 to 40 for the upper eyelid and 20 to 30 for the lower eyelid.
These glands secrete oil substance, meibum, which coats the surface of our eyes and keeps the water component of our tears from evaporating (drying out)
Glands that produce tears.
Eye disease due to a rise in eye pressure leading to damage to the optic nerve and the visual field. Two major types are acute glaucoma (or angle closure glaucoma), which is relatively rare, and chronic glaucoma (or open-angle glaucoma), the most common form.
The estimated number of people blind due to primary glaucoma is 4.5 million and represents more than 12% of global blindness. (* Source WHO)
Visual defect characterized by a clearer vision from afar than near, due to an eye that is too “small” or not powerful enough. As a result, images form behind the retina.
Major cause of dry eye (80% of cases). The lipid layerof the tear film is altered and no longer performs its anti-evaporative role despite the production of tears in sufficient quantity.
Insufficient production of tears by thelacrimal glands.
The colored tissue at the front of the eye that contains the pupil in the center. The iris helps control the size of the pupil to let more or less light into the eye.
A liposome is a spherical-shaped vesicle that is composed of one or more phospholipid bilayers, which closely resembles the structure of cell membranes.
Oily substance produced by the meibomian glands. Its role is to slow the evaporation of tears.
Visual defect characterized by a blurred vision from afar but clear up close, due to an eye that is too “long” or too powerful: the distance between the cornea and the retina is too great. As a result, images are formed in front of the retina.
Nerve that transmits images as a nerve impulse to the brain. It measures approximately 5mm in diameter and 35 to 55mm in length.
Amphiphilic lipids: they are made up of a hydrophilic part and a hydrophobic part.
Visual defect characterized by difficulty in seeing up close, due to the natural aging of the lens, which loses its flexibility and therefore its capacity to adapt. Presbyopia is corrected with suitable glasses.
Central opening of the iris through which light rays enter the eye towards the retina.
Nerve membrane lining the back of the eye on which images are formed which are transmitted directly to the brain.
Dry eye is a disease of the tears and the surface of the eye that causes symptoms of discomfort, visual disturbance, and tear film instability with potential damage to the ocular surface.
There are 2 types:
Spray solution applied directly to the eye. (Learn more)
Simple alternative to eye drops and eye ointments.
Autoimmune disease manifested by sicca syndrome, affecting more particularly the salivary glands and lacrimal glands. It affects 0.1 to 0.4% of the population. Among those affected, women represent 90% of cases.