Glaucoma is a term describing a group of ocular disorders with multi-factorial etiology united by a clinically characteristic intraocular pressure-associated optic neuropathy. This can permanently damage vision in the affected eye(s) and lead to blindness if left untreated. It is normally associated with increased fluid pressure in the eye (aqueous humour). The term "ocular hypertension" is used for people with consistently raisedintraocular pressure (IOP) without any associated optic nerve damage. Conversely, the term 'normal tension' or 'low tension' glaucoma is used for those with optic nerve damage and associated visual field loss, but normal or low IOP.
Retinopathy (damage to the retina) is caused by complications of diabetes, which can eventually lead toblindness. It is an ocular manifestation of diabetes, a systemic disease, which affects up to 80 percent of all patients who have had diabetes for 10 years or more. Despite these intimidating statistics, research indicates that at least 90% of these new cases could be reduced if there was proper and vigilant treatment and monitoring of the eyes. The longer a person has diabetes, the higher his or her chances of developing diabetic retinopathy.
A cataract is a clouding of the lens inside the eye which leads to a decrease in vision. It is the most common cause of blindness and is conventionally treated with surgery. Visual loss occurs because opacification of the lens obstructs light from passing and being focused on to theretina at the back of the eye. It is most commonly due to biological aging but there are a wide variety of other causes. Over time, yellow-brown pigment is deposited within the lens and this, together with disruption of the normal architecture of the lens fibers, leads to reduced transmission of light, which in turn leads to visual problems. Those with cataracts commonly experience difficulty in appreciating colors and changes in contrast, driving, reading, recognizing faces, and coping with glare from bright lights.
Allergic conjunctivitis is inflammation of the conjunctiva (the membrane covering the white part of the eye) due to allergy. Although allergensdiffer between patients, the most common cause is hay fever. Symptoms consist of redness (mainly due to vasodilation of the peripheral small blood vessels), oedema (swelling) of the conjunctiva, itching and increased lacrimation (production of tears). If this is combined with rhinitis, the condition is termed allergic rhinoconjunctivitis. The symptoms are due to release of histamine and other active substances by mast cells, which stimulate dilation of blood vessels, irritate nerve endings and increase secretion of tears. Treatment of allergic conjunctivitis is by avoiding the allergen (e.g. avoiding grass in bloom during the "hay fever season") and treatment withantihistamines, either topical (in the form of eye drops), or systemic (in the form of tablets). Antihistamines, medication that stabilizes mast cells, and non-steroidal anti-inflammatory drugs (NSAIDs) are safe and usually effective.
Age-related macular degeneration (AMD) is a medical condition which usually affects older adults and results in a loss of vision in the center of the visual field (the macula) because of damage to the retina. It occurs in "dry" and "wet" forms. It is a major cause of blindness and visual impairment in older adults (>50 years). Macular degeneration can make it difficult or impossible to read or recognize faces, although enough peripheral vision remains to allow other activities of daily life. Starting from the inside of the eye and going towards the outer surface, the three main layers at the back of the eye are the retina, which is light-sensitive tissue that is considered part of the central nervous system and is actually brain tissue; the choroid, which contains the blood supply; and the sclera, which is the white, outer, layer of the eye.
Retinal detachment is a disorder of the eye in which the retina peels away from its underlying layer of support tissue. Initial detachment may be localized, but without rapid treatment the entire retina may detach, leading to vision loss and blindness. It is a medical emergency. Permanent damage may occur, if the detachment is not repaired within 24-72 hours. The retina is a thin layer of light sensitive tissue on the back wall of the eye. The optical system of the eye focuses light on the retina much like light is focused on the film or sensor in a camera. The retina translates that focused image into neural impulses and sends them to the brain via the optic nerve. Occasionally, posterior vitreous detachment, injury or trauma to the eye or head may cause a small tear in the retina. The tear allows vitreous fluid to seep through it under the retina, and peel it away like a bubble in wallpaper.
Amblyopia, also known as lazy eye, is an eye disorder characterized by an impaired vision in an eye that otherwise appears normal, or out of proportion to associated structural abnormalities of the eye. It has been estimated to affect 1-5% of the population. In amblyopia, visual stimulation either fails to transmit or is poorly transmitted through the optic nerve to the brain for a continuous period of time. It can also occur when the brain "turns off" the visual processing of one eye to prevent double-vision, for example in strabismus (crossed-eyes). It often occurs during early childhood, resulting in poor or blurry vision. Amblyopia normally affects only one eye in most patients. However, it is possible, though rare, to be amblyopic in both eyes, if both fail to receive clear visual images.
Strabismus is also known as squint and heterotropia (and including the two variants cross-eye and walleye), is a condition in which the eyes are not properly aligned with each other. It typically involves a lack of coordination between the extraocular muscles, which prevents bringing the gaze of each eye to the same point in space and thus hampers proper binocular vision, and which may adversely affect depth perception. Strabismus can present as manifest (heterotropia) or latent (heterophoria) varieties, and can be either a disorder of the brain in coordinating the eyes, or of the power or direction of motion of one or more of the relevant muscles moving the eye. Strabismus is primarily managed by ophthalmologists, optometrists and orthoptists. Strabismus is present in about 4% of children. Treatment should be started as soon as possible to ensure the best possible visual acuity.