Eye Care Blog

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.

Conjunctivitis occurs at times of illness, low resistance to contagious infections or when the eye surface and lids suffer repeated irritation from the atmosphere. The latter can be due to industrial atmospheric pollution or even badly controlled ventilation. Low resistance to infection may be due to the fact that the young person has never met that type of infection before or the normal body processes that fight infection (immune reactions) may be deficient for one reason or another. In boarding schools, where both diet and age factors are present, contagious conjunctivitis often spreads rapidly through the entire community. On the other hand, a serious attack of a virus illness such as measles may affect the skin of the eyes as well as the mouth in the early stages and persist if not treated. Since conjunctivitis is so common and the organisms that can cause it range from the simple staphylococcus of the skin to the dreaded gonococcus of venereal disease, it behoves everyone living at close quarters with fellow humans to use the simple methods of hygiene and maintain positive health.

The question is often asked, ‘If something enters my eye, or if my contact lens comes off the cornea, can it go behind the eye? Can it slip round to the back?’ The answer is no, it cannot. The conjunctiva is joined to the eyeball at the point where it folds back on itself. If a foreign body is allowed to lodge under the conjunctiva, however, it may easily become inflamed. Here the deeper tissues of the lid that carry the blood vessels provide the tools for the process of inflammation.

When inflammation is exaggerated relative to its cause the condition may be apprehended as an allergic reaction. Examples of this are reactions to drugs and chemicals, pollens, house dust, animals and even cosmetics.

Some creatures sleep with their eyes open, even though they have eyelids (whose original evolutionary purpose is to keep the eye clean and lubricated). The advantage of sleeping with the lids closed is twofold: it prevents stimulation of the brain from light entering the eye, and it prevents the cornea from drying. Blinking of the lids during the waking period is essential to wipe the cornea free from debris and to keep the tear film evenly spread. Blinking also enables the eyes to move without the brain receiving several conflicting pictures until the eye is in its chosen position.

Most fish do not have eyelids, but then, since they live in a watery environment they do not need to have them. They do not have tear glands because they live in what could be called one vast tear. The rapid staccato movements of many smaller fish achieve the function of blinking when they wish to shift their view. If you look at goldfish in a tank you will notice that though their bodies quiver, their heads are held remarkably still.

As the human grows older the fat behind the eye shrinks and the eye itself ’sinks back‘. This may be associated with looseness of the skin round the eyes and weakness of the muscles that encircle the eyelids. These muscles are used to open and close the lids. When used excessively they can exert a great deal of pressure on the eyes. They can in fact ’screw up’ the eyes and decrease the palpebral aperture (pupil) and improve vision by reducing the number of rays entering the eye. (Remember how looking through pinholes or small slits negates some aberrations in the optical system.)

The combination of muscular atrophy and sunken eyeballs often results in the lower lid becoming loose, and this in turn leads to tears spilling over the lids and running down the cheeks. Old people therefore have a natural tendency to ‘cry’, regardless of their emotions. This is particularly the case in cold weather, when the lid margin becomes red and the lower lid sore. On the other hand, the muscle in the lower lid may momentarily go into spasm, and then the lower lid inverts. This results in the eyelashes rubbing against the eyeball, an irritating and sometimes painful condition, which may also occur in infancy. Whilst the baby will nearly always grow out of the problem as the eyeball increases its size, the elderly adult can expect no such succour and, where the condition is severe, may have to undergo surgery to tighten the loose tissues. Such surgery is minor, however, and the outcome is usually very good.

There are several treatments for inverted eyelashes. The simplest is the pulling out of the lashes, but these inevitably grow again; and if they are broken stubby ends can give as much aggravation as the complete lash. A more permanent method is to freeze the lid and kill the lash follicle (or bed of origin). Electrolysis can be used. But where the condition is intractable the use of surgery to turn the lash margin outwards again is best. In desperation, contact lenses can be used to protect the front of the eye from the lashes.

Loose skin round the eye of the elderly person is often disfiguring, and some patients ask for what in effect is a form of plastic surgery for cosmetic reasons. But it may be more than disfiguring. Loose skin may hang down over the cornea, in which case it occludes vision. To cut away such skin and tighten the lids is a relatively simple operation, and, if done expertly, the results may be excellent. But there can be complications in the healing process, and so it is not necessarily advisable to operate.

Watering of the eyes in infancy and childhood may be associated with non-development of the tear-drainage system. Excess tears normally drain into the lower lid hole (punctum) at the inner corner of the eye, passing back into a sac which allows the fluid to enter the back part of the nose. Thus watering of the eyes, either from irritation or crying, will lead to excess tears running backwards through the nose into the throat. Hence people who cry profusely tend also to sob.

If the tear-duct does not develop during the first year of life a fine blunt probe can be passed (under general anaesthetic) through the punctum backwards into the nose. Very often this is all the treatment required. In adults, however, obstructions of the tear-drainage system can only rarely be corrected by simple washing out or probing of the ducts. If the condition is very troublesome it may be necessary to undergo an operation that provides a new duct between the sac and the internal nose cavity, but such an operation is not always successful.

Finally, there are several non-senile conditions where the upper lid hangs down, owing either to a weakness of the eyelid muscle or the non-functioning of the nerve-supply. Such a condition is called ptosis. In infancy it may be just one eye which is ptosic. Unless the lid can be made to open and close, surgery is necessary, but again the results are variable. Even in expert hands the cutting of tissue does not always lead to the desired outcome. Where surgery is desired for mere cosmetic reasons it should be approached with caution, for it is an unwise surgeon who promises perfection.

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