The colour of your eyes is inherited. The colour and pattern of the iris are as individuated as fingerprints. It is coated on its back with brown-black pigment. This prevents light penetrating to the back of the eye except through its centre, or pupil. This hole can change its size, dilating or contracting as the level of light requires. In bright light, or when we wish to scrutinize a near object, it contracts. In dull light, or when we wish to relax our eyes and stare in the distance, it dilates. It also becomes bigger if we are frightened or excited, and it dilates in death. Read the rest of this entry »
When examining you an ophthalmologist will test eye-pressure through the simple expedient of placing his fingers on your closed eyelids. The experienced physician will know immediately whether the pressure is unusually high, but even so he is unlikely to be able to distinguish, using this technique, between more than four grades: namely soft, normal, suspicious and high. Accurate measurement requires instruments. Such instruments have to touch the cornea, which is therefore suitably anaesthetized beforehand, using a special kind of drop. Several types of local anaesthetic drop exist, e.g. amethocaine, pentocaine and xylocaine. One instrument blows a puff of air on to the cornea and then measures the degree of corneal flattening that results. This does not require a local anaesthetic. Read the rest of this entry »
The lids consist of movable tissue. Inside they are coated by a smooth, delicate tissue-membrane which, if traced up and down, forms a fold coming back on itself and then enveloping the eye, but stopping at the edge of the cornea. This fine membrane is called the conjunctiva. Thus the inside of the lid and the surface of the eye are in direct contact, more so when the lids are closed and the cornea itself is covered. Sometimes this membrane becomes subject to a mild infection, of a non-specific type, and the result is conjunctivitis. This is not usually a serious condition, and is easily treated either with drops or by bathing the eye in a prepared solution. The symptoms are irritability, discharge, redness, particularly along the top edge of the lower lid, and occasionally swelling. Most people will experience conjunctivitis at least once in their lives. Some have more than one attack each year. People who wear contact lenses are more prone, since the daily routine of placing lenses on the eye offers a greater opportunity for an infective organism or irritant chemical to reach the eye. Read the rest of this entry »
Squint, or strabismus, is a general term used to describe any one of several conditions in which the two eyes are not properly co-ordinated. One eye focuses on an object, but the other eye fails to align itself to the same fixation. Most commonly the errant eye is aligned inwards (cross-eye or esotropia) or outwards (wall-eye or exotropia); less commonly it looks upwards (hypertropia) or downwards (hypotropia). Other words to describe these conditions are ‘cast’ and ‘turn’. The phrase ‘evil eye‘ has also doubtless been used in association with squint. Where a squint remains uncorrected the person who has it is often forced to adopt an unusual, even grotesque, head- posture, adding to a general impression of unsightliness. But because the squint sufferer has the potential for normal stereoscopic vision the treatment of squint is an important ophthalmic activity. Read the rest of this entry »
As regards lens-implant surgery the benefits are very great. To be able to have normal sight again without the need for thick spectacles or the bother of wearing contact lenses is surely the preferred treatment. Where contact lenses are used subsequent to a cataract operation, they differ from ordinary contact lenses in certain ways. The condition of an eye that has had its crystalline lens removed is known as aphakia, and aphakia almost invariably demands a contact lens that is much thicker in its centre than the lens worn by the ordinary short-sighted person. Read the rest of this entry »
At the beginning of this century the most prominent cause of blindness was infections of the eye. The eye is exposed externally to infections because of the very delicate skin-lining of the lids and sensitive outer membrane of the eye itself. Other tissue areas of equal susceptibility to infection are the nose, mouth and genitalia. It is even possible for all these orifices to be infected by the same organism.
Since the the availability of antibiotics has drastically reduced the incidence of chronic consequences following an infection. Many serious infections, provided they are treated quickly, no longer inflict severe damage. Read the rest of this entry »
More familiar to us are X-rays, harmful to our tissues in large doses. They can cause cataract and retinal damage. In practice X-rays used for diagnostic purposes are of low dosage, and their effects, both as regards the patient and the practitioner, are controlled. In high intensity they can be used in narrow beams to burn away tissue. (Laser is an example of concentrated light rays.) If such beams are directed on the eye, immediate and irreparable damage would be done. The eye is designed to cope with normal light, i.e. that part of the light (electro-magnetic radiation) between the infra-red and ultra-violet parts of the spectrum. The spectrum extends considerably further in each direction, and the eye can only absorb small low-dosage radiations from these outer areas. In outer space such radiations abound, but the earth’s atmosphere acts as a screen protecting us from harmful rays. Read the rest of this entry »
This not always possible for people to go to a competent I physician for relief. As the method of treating eye defects presented is comparatively new, it may be impossible to find a physician in the neighborhood who understands it, and a person may not be able to afford the expense of a long journey or take the time for treatment away from home. To such persons I wish to say that it is possible for a large number of people to correct defective eyesight without the aid either of a physician or of anyone else. Read the rest of this entry »
At the request of the superintendent of schools in Grand Forks at that time, the system was introduced into all the schools of the city and was used continuously for eight years. During this time it reduced myopia among the children, which I found at first to be about six per cent, to less than one per cent.
A few years later the same system was introduced into some of the schools of New York City, with an attendance of about ten thousand children. Many of the teachers, however, neglected to use the cards, being unable to believe that such a simple method, and one so entirely at variance with previous teaching on the subject, could accomplish the desired results. Read the rest of this entry »
