In all elderly persons the lens of the eye gradually becomes harder, less elastic, and somewhat yellow; when these senile or degenerative changes take place and cause part or total loss of transparency of the lens, the condition called cataract is present. Often the cause is not known, but certain recognised diseases, such as diabetes mellitus, are liable to give rise to cataract; injuries, accidents, or foreign bodies in the eye may also be responsible, and the condition is commoner in people over sixty years of age although cataract is sometimes seen in younger persons.
It is important for the specialist to recognise the different types of cataract since the out-look varies, some cataracts advancing to complete opacity of the whole lens, while others remain more or less in the same state. The urine should always be tested for sugar and albumen to detect diabetes or disease of the kidneys.
If the opacity is in the centre of the lens it is called a nuclear cataract, while at the edge it is said to be cortical. Nuclear cataracts generally develop in old people, producing the senile type, but they may be present during middle age.
Cataracts may be hard or soft; the hard type is senile, and the lens can be removed by means of an extraction operation. Soft cataracts may occur in children or people under thirty years, and are removed by 'needling' or suction.
Senile cataract generally develops in people after forty-five or fifty years of age, and is caused by shrinkage. This type of cataract causes dark spots and dimness of vision, especially for distant objects, or there may be double vision, when objects are seen double. Progress is variable and the cataract may take two or three years to mature or ripen, when it becomes milky-white. Central cataract is slower than the cortical type.
Cataract often affects both eyes, but usually develops in one eye before the other. In the early stages suitable glasses often improve the sight.
Extraction of the lens by operation and the provision of suitable glasses is undertaken for mature cataracts. Only one eye should be operated on at a time, since occasionally iritis or some other complication may follow. When one eye is affected before the other, it is usual to post-pone the operation while the patient still has fairly good sight in the second eye.
The cornea or transparent coat of the eye in front of the pupil usually heals quickly in successful cases, but skilled nursing is essential. Care must be taken when the patient is up and about to avoid knocks, or straining such as sneezing or coughing, which may open the wound or cause the vitreous humour of the eye to be squeezed out.
Diabetic cataract is a type of cataract similar to the senile cortical type, and always affects both eyes. It ripens quickly, but the possibility of surgical treatment depends on the patient's general health.
Cataract Due to Lens Injury
Cataract due to injury of the lens may develop within a few days if a sharp instru-ment pierces the lens capsule, and iritis is likely to follow, for which atropine drops should be instilled three or four times a day as a preventive. Sometimes surgical treat-ment is required if there is much pain, but is generally avoided when possible. Other types of cataract, such as the secondary type that may follow glaucoma, hereditary cataract, and cataract after gonor-rhoeal inflammation in the eyes of infants, also occur. ‘Needling’ operations are used to break up soft cataracts; the lens capsule is torn. The softened lens becomes absorbed by the aqueous humour in the front part of the eye.
Cataract is sometimes, though wrongly, suspected especially by a short-sighted person, when small floating spots, specks, threads, or chains of spots are sometimes seen to pass across the eye. These small particles are the remains of cellular fragments present during the development of the eye. When the eye is moved the spots or threads are jerked about and then slowly sink; they can often be perceived by looking at a white ceiling or light wall. They are not of serious import, and only opaque particles that can be detected by an ophthalmoscopic examination are likely to be a sign of any disorder of the eyes.
Similar of Cataract