Examination of the eye is essential at regular intervals to ascertain the functional health of this vital organ.

How frequently should the eye be examined?

Upto the age of 40, an eye examination once in 2 years is usually adequate, unless there is a reason for an earlier visit like redness or a fall in vision or eye strain. After the age of 40, it is mandatory that the eye be examined every year.

When should my child have his eyes examined?

The first eye examination and perhaps the most important is before the age of 6 months.

A fair number of eye diseases can be detected and treated at this early age. After 6 months, if, for any reason, light has been prevented from entering the eye, the fovea of the retina does not develop and no treatment done in future can help.

The second eye examination is at the age of 18 months to 2 years. At this age the development of the eye is almost complete. Again, any treatment which may be required should be instituted at this stage.

The next important date is at the age of 4 years. By this time the muscular development of the delicate eye muscles is complete. Any imbalances should be assessed and evaluated. At this stage muscle exercises to control imbalances are extremely effective.

Again: 2 years later, at the age of 6 years. The optical aspects of the eye are complete. Any residual hypermetropia can be easily detected and checked.

Subsequent eye examination dates should be at intervals that do not exceed 2 years.

It is important to remember that a vision check is only part of eye care. Merely checking spectacle number in a shop does not comprise an eye examination.

What does an eye examination consist of?

The eye examination can be divided into three categories: (1) Examination of vision for distance and near. (2) Examination of muscle balance. (3) Examination of the outside and inside of the eye or the structural examination of the eye.

What are the preliminary stages prior to eye examination? What should you tell the doctor?

A doctor can tell a lot by simply looking at an eye while the patient is talking. Any undue swelling, changes in lid position, excess blinking, instability in eye positions are automatically detected. Muscular paralysis or weakness is also detected by the angle at which the head is held. The head tries to rotate the eyes in a position where the paralysis would not affect the vision—this is termed compensatory head posture.

However, it is important to tell the doctor about your general health. If you have hypertension or diabetes or any illness, tell him about the drugs you take and their dosages. Since the eye is really an extension of the brain and the body, whatever affects the body can cause changes.

It is also important to mention when you had your last check-up, and your old spectacle number and prescription for eye drops or drugs, if any.

The doctor is also interested in knowing if you had any episodes of redness or pain in the eye. Also if the eyes feel itchy.

It is a good rule to note the complaints and your personal medical history, in brief, on a slip of paper and take it with you. It has two advantages: the most important being the obvious one that you do not forget to tell something which may prove to be important, and secondly, it presents a coherent summary to the doctor who can then give more attention to your case.

All previous prescriptions and spectacle records are best carried clipped together, being thus far easier to maintain and display. It permits one at a glance to note changes which are occurring in the power of the eye.

What does vision examination entail? How is vision gauged?

The vision has to be tested for distance and near separately. Distance vision is tested at a distance of 20 feet or 6 metres, as rays of light from a point this far are nearly parallel.

The type of test letters on a chart (termed test-type) is accurately based on an optical size for a fixed distance, termed Snellen chart.

The size of the letters diminishes from the top downwards. The uppermost letter is of such a size that it can be read at 60 metres. The following rows of letters should be read at 36, 24, 18, 12, 9 and 6 metres by a normal eye.

The acuity of vision is expressed by a fraction, the numerator of which corresponds to the number of metres separating the patient from the chart (6 metres) and the denominator indicating the distance at which the smallest row of letters read by the patient should be read by a normal patient. If the patient's sight is normal, his acuity of vision equals 6/6. If he can read the third line from the top it is 6/24; if only the top letter, 6/60.

Most sophisticated charts have an illumination device from behind so that the intensity remains constant.

Dustin Flores

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