13.07.2006 Health


By Enyam Marny
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Dr. F. Kojovi Morny, MA, OD, D.Optics, Diploma in Orthoptics, FBCO, FGOA

You must have seen people with “crossed eyes” known as “squints” on stage at public functions. Such public speakers may wish they could hide their deformity, but in vain. Such are those whose eye care was neglected by their parents in childhood. This article looks at the importance of why parents must be more aware of their children's eyes and vision so that children can reach their full visual potential.

Records state that 76% to 90% of everything a child learns comes from what he sees. The eyes can be compared to two digital cameras, which need to be linked by a wiring system to a computer in order to produce pictures. The computer in this case, is the brain. As long as each eye produces a good picture, the brain will put the two impressions together and create a 3-dimensional (3-D) object (i.e. solid body not a flat picture). If unfortunately the picture from one eye is inadequate, the brain will ignore it and will use only the clear picture coming from the other eye, resulting in abnormality of the eye.

At birth, the eye is not fully developed in size and full seeing ability, but by six months, the baby's vision is vastly established. At this stage, a family with history of squint and lazy eyes should be on the lookout for such abnormalities in their children, and if in doubt, the child should have specialist eye examination and attention before 18 months, to catch any anomalies early.

If a “turn-in-eye” (referred to as “convergence squint or strabismus) appears in the first six months of life, it is usually easily noticed, as the child appears “cross eyed”. It must be noted that surgery is normally required before the child is 12 months old to ensure the best chance of visual development. Luckily, 60% of convergence squint can be corrected, or “made straight” by wearing spectacles, as these squints are associated with hyperopia (long sightedness); however the remaining 40% of convergence squints will require both surgery and spectacles. Again Surgery during the early years helps to ensure that the eye develops properly in a straight-ahead position, whereas squint surgery after the age of six years is simply cosmetic.

It is estimated in UK, that 2-3% of children are affected by “lazy eyes”, which optometrists call 'amblyopia'; this is where there is reduced vision in usually one eye, although in extreme circumstances, both eyes can be affected.

If a child under six year is found to have reduced vision in one eye, appropriate spectacles are prescribed, and orthoptic treatment by patching the good eye for certain periods of the day is recommended. Patching the good eye forces the brain to establish a connection with the previously bad eye. Over time, the poor eye begins to see well.

Eyes are designed to work better in 'stereo', just as how stereo sound is superior to mono. Stereo vision is responsible for being able to see objects in solid form and in space. This depends upon the two eyes working well together as a team. Thus when there is a significant difference in refractive error, wearing spectacles will help develop this facility.

A child not treated early enough for a squint, or for amblyopia will never have 3-D vision. Luckily the amount of 'stereopsis' can be measured using variety of tests- such as Polaroid lenses and/or Red and Green lenses by doctors of optometry.

Eye development is very rapid in the pre-school age group (3-5 years), thus it is vital that any potential vision problems should be detected at this stage to achieve the best treatment. Some parents wrongly think that as their children do not know the alphabets, examination of their eye is not possible. This is not true; vision could be measured subjectively at that age using pictures of different sizes called “Kay picture cards”, or for the more advanced children, by comparing single letters on a card called the “Sheridan Gardiner test.

Subjective vision measurement (done by questions and answers) is important, but the optometrist is able to measure the prescription of eyes using an objective technique called 'retinoscopy'; where a streak or spot of light is passed across the pupil, and the way the light moves determines the prescription of the eye. In some eye examinations, eye drops (cycloplegics) are used to temporally relax the focusing ability of the eye (accommodation), so that a consistent and accurate result can be obtained.

During 4 to 16 years, the educational environment highlights problems previously unnoticed; and children are also more able to report their symptoms or experiences. It is then that the child's teacher might be the first to notice a squint or a strange habit of periodically covering one eye during detailed work, reading, or copying from the board, which indicates visual difficulties. It is then that some children require spectacles, and/or orthoptic eye exercises, such as “pencil to nose” exercise to improve the ability of the eye to work together for near tasks under supervision of the doctor of optometry and parents.

During adolescence, significant growth of the eye changes its size. For hyperopic children, this may lead to a reduction in their prescription; and for others, myopia may start to develop. Education of parents on the impacts of growth spurs on the eye is needed, so that more frequent eye examinations must be made. Usually, teenagers are more self-conscious about their spectacles; and it is then also that some school activities such as sports and swimming interfere with spectacles wearing. A good advice on appropriate eyewear, such as swimming goggles and contact lenses (which is not yet common here in Ghana), can make a significant difference to their self-esteem and performance.

A child must feel happy wearing his spectacles, or it will not be worn at all. This will not only waste their parents' money, but they also will not be receiving the full therapeutic benefit from the correction. At times the dislike may be due to faults, especially with heavy lenses which tend to pull the spectacles down the nose; for this, only a good fit is needed. Here, a dispensing optician or an optometrist must assist in the choice of frame. Parents should be made aware of the availability of thinner, lightweight, reflection-free lenses especially in the case of heavier, high prescription. On the other hand, an amblyopic correction, for example, means that the good eye requires little or no help from the glasses. Some children often peer over the top of the frame leaving the amblyopic eye untreated; parent supervision is needed.

Safety is the prime consideration for children wearing spectacles. Plastic or polycarbonate lenses which are toughest must be dispensed with a scratch resistant coating.

Finally, it is vital that parents understand that a child will not 'grow out of a squint' or most other eye problems. The problem must be treated at the earliest opportunity and certainly before age six. The other age groups too must not be ignored. Luckily, two universities in Ghana are running comprehensive 6-year Doctor of Optometry programs to train optometrists competent to manage these anomalies of vision.

The Author
Dr. F. Kojovi Morny is a renowned Doctor of Optometry and orthoptist who owns and practices at Morny Eye Care Centre in Kumasi, Ghana. He is a Fellow of the British College of Optometrist and the Ghana Optometrists Association. He established the two Doctor of Optometry programmes in the University of Cape Coast, and the Kwame Nkrumah University of Science and Technology in Ghana. He is currently also a visiting scholar, Optometry Department, UCC. He was the 2005 World Council of Optometry Prize Winner and is acclaimed the “Father of Optometry in Africa”.

Article submitted with permission from the Author by
Enyam Morny,
University of Cape Coast, Ghana

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