Since the retinal nerves radiate from the cup of the optic nerve (the seat of the blind spot) the loss of retinal function tends to occur in a way that is diagnostic. For example: the group of nerve fibres that tend to be affected first are those that function in arches around the centre of vision. The next group to go are those providing vision in the nasal field (the lateral part of the retina). But it is all too possible for a patient to be unaware of these losses of vision, and because the condition is symptom-free in its early stages and only gradually progressive, diagnosis is often difficult. 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 »
The eye has its natural protective mechanisms. The lids, for example, protect the front of the eye from dust, wind and objects coming towards the face. They also protect the eye from excessive light. The eye itself is set in its bony cavity: the orbit. In the orbit there are some soft fatty tissues which act as a cushion, permitting the eye to sustain a light blow without injury. Nevertheless the eyes are vulnerable. The eye will be injured, often severely, by fast-flying hard objects, and also by some gases and solutions. It is easy to incapacitate a human being, either temporarily or permanently, by spraying irritant solutions onto the face, and such methods have been widely used by criminals, police and the armed services. Read the rest of this entry »
