Variety Of Causes For Loss Of Sight

Press, Volume CII, Issue 30191, 24 July 1963, Page 10

Variety Of Causes For Loss Of Sight

In later life, time can pass slowly if poor sight makes reading and other sedentary hobbies impossible. This distressing loss of vision can be due to a large variety of causes, some of which are common, ana many of which are rare. These causes fall into three categories: those conditions which can be remedied or cured; those in which further deterioration of vision can be prevented; anti those for which, as yet, no treatment can be offered.

If an older person becomes aware that he or she is seeing less clearly and does not seek appropriate medical advice this may not matter much if. at a later stage, vision can be restored with treatment or on the ,other hand, if nothing be done to arrest the deterioration of vision. However, if the failure of vision happens to be due to one of the causes in the second category, delay in seeking expert attention may be nothing less than tragic, because in these cases what has been lost is irrecovably lost and also because treat-

ment is commonly only really effective in preventing further loss of vision if it is instituted in the early stages of the complaint. By far the most important cause of this type of visual loss is due to a group of eye diseases known as glaucoma. The various types of glaucoma have in common an increase in the pressure inside the eye-ball and the eventual total destruction of vision. Glaucoma is more common with advancing years. The number of people suffering from these conditions who are already under treatment in New Zealand is not known, but there are several thousand of them. Strange Symptoms One type of glaucoma in its early stages gives rise to strange symptoms. Affected people experience attacks in which their vision is slightly blurred and their eyes are vaguely uncomfortable, and the observant ones notice rainbow coloured haloes around lights at night, much the same as may he seen when looking through a misted car window at a naked street light. These episodes are transient, and rarely obtrusive, and therefore it is common for them to be disregarded. If they are ignored and appropriate treatment not instituted, eventually a much more dramatic attack is likely. In this, the eye becomes agonisingly painful and the vision is profoundly reduced in a matter of hours. If this acute attack is not urgently treated permanent loss of sight in the affected eye is inevitable. However, appropriate treatment can prevent such disastrous attacks from ever occurring if the full significance of the warning episodes of blurred vision and haloes is appreciated. Similar haloes around lights can be due to other causes, such as the early stages of cataract formation, but they should never be regarded as meaningless curiosities. No Warning

People who suffer from another and much more common type of glaucoma are given no warning that they are suffering from this condition. It is a silently treacherous destroyer of vision which over a period of years so slowly diminishes sight that the affected person is quite unaware of what is happening. There is no pain, the eye looks clear and normal on the outside and activities such as reading are not in any way impaired. By the time the patient becomes aware of his failing sight the condition is so firmly established that treatment is disappointingly unsuccessful. Early Diagnosis Essential In other words, for fully effective treatment this condition must be diagnosed before it has caused any symptoms. If diagnosed at an early stage and effective treatment is embarked upon, further

loss can be prevented in almost all cases. In the majority of these early cases, the treatment necessary is the application of drugs of various types to the eye, usually in the form of eye-drops. This treatment is not truly curative. It will only control the condition and therefore must be consistently used for the rest of the patient’s life. This, however, is a small price to pay for normal sight. In a few cases surgical treatment is necessary to lower the pressure inside the eyeball to a level at which further destruction of the delicate tissues inside the eye does not occur.

The paramount importance of early detection of glaucoma will be obvious and it will also be obvious that this can only be achieved if people from the age of fiftyfive to sixty years regularly submit their eyes to medical examination for the specific purpose of determining whether or not they are suffering from early glaucoma. In surveys undertaken in some overseas countries, it has been found that 2 per cent of the population over the age of 40 years is suffering from unsuspected glaucoma. Until such time as a comprehensive scheme of eye examination for older people can be provided in New Zealand, it is up to the individual to seek this examination for himself.

This article was prepared for the New Zealand Foundafor the Blind bp a senior ophthalmologist.