There are further classifications according to lens design, finish, colour, etc., which make the whole subject very confusing. If you want what is best the answer must be, ‘Whatever your practitioner advises as the best optical correction according to your eye sensitivity and required duration of wear.’ The classifications given are in fact properties of the lens, and a combination of them gives a particular kind of lens. Some types are commercially available by trade names on an `off-the-shelf’ basis, others have to be manufactured by specification. They are all made of plastics, however, though some absorb water while others do not. Most absorb and transmit gas, a necessary function to maintain the chemical equilibrium of the eye-system. Read the rest of this entry »
At the beginning of this century the most prominent cause of blindness was infections of the eye. The eye is exposed externally to infections because of the very delicate skin-lining of the lids and sensitive outer membrane of the eye itself. Other tissue areas of equal susceptibility to infection are the nose, mouth and genitalia. It is even possible for all these orifices to be infected by the same organism.
Since the the availability of antibiotics has drastically reduced the incidence of chronic consequences following an infection. Many serious infections, provided they are treated quickly, no longer inflict severe damage. Read the rest of this entry »
Contusions
Severe blows to the face and eyes are relatively rare in life; but casual blows and knocks are common, occurring mostly in the home or on the sports field. For those involved in warfare they are common enough injuries. Explosions exert great changes of air pressure upon the body, followed by a rebound as the pressure suddenly drops again. This is the invisible fist of the battlefield, and of some industrial accidents. The eye can be convulsed from its muscle connections and the orbit severely damaged. Most explosions are also associated with flying debris (it could be shrapnel, it could be glass), so that injury is often compounded by different types of damage. Other instances where contusive damage occurs are motor accidents, especially where safety belts are not worn, champagne bottle corks, squash balls and fireworks. Read the rest of this entry »
