What kind of eyes do I have?

Normal conditions requiring correction

The human eye is both simple and complex. In its simplest form the eye works by focusing using a lens and passing the light onto a membrane (the retina) which converts the light into neural signals. Once you understand this you can see the key areas where the process can go wrong:

• Short -sightedness - (also known as myopia) is caused when the eyeball is too long (or the cornea too steep) resulting in the focal point being in front of the retina. Near objects are clear enough, but distant objects appear blurred.
• Far-sightedness – (also known as hyperopia) is the opposite of short-sightedness but with the inverse causes.
• Astigmatism – (not a stigmatism!) is caused by irregular shaping of the eye. A perfect eye would be spherical in shape whereas in the case of astigmatism certain parts are longer than others (imagine a rugby ball on its side). This is cured by toric contact lenses.

Clearly, you may have combinations of the above at the same time but no degree of complexity per se prevents you being able to wear contact lenses.

All of the above will become apparent either from birth or more often will develop during your school years. Although various methods may be tried to stabilize certain conditions, you are most likely to reach a point of stability at some point. Subsequently from your mid 20’s until your mid to late 40’s your eye-sight will more or less stay the same (with some exceptions). You may find yourself attending your annal contact lens aftercare and paying your money for up to 20 years without any appreciable change.

Conditions affected by ageing

Ageing results in another problem – presbyopia. Basically the muscles which control the focussing become less adept at changing the point of focus. It also becomes harder to see near objects (particularly in the case of reading) and your life will be overtaken by reading glasses. Typically, this is when many people abandon contact lenses (why bother with lenses when you need to carry glasses around?) but actually there are 2 proven solutions:

• Bifocal / multifocal contact lenses (a relatively recent solution), which work in very much the same way as bifocal or varifocal glasses.
• Monovision, which involves wearing a lens for distance in one eye and a lens for near in the other. It sounds strange (and actually some people cannot get along with it) but it works and many people quite happily make the transition.