Inflammation of the membrane which lines the eyelid (conjunctiva) is known as simple ophthalmia or conjunctivitis. The disease may present itself in various forms, from the acute to the chronic. In all stages of the disease the normal secretion from the membrane undergoes certain changes, and in the human subject the terms catarrhal, purulent, and diphtheritic ophthalmia are employed to indicate the nature of the discharge.

Causes of simple ophthalmia are - exposure to cold, the action of irritating gases, dust, bits of chaff, and other foreign particles, injuries, and it is very often associated with febrile diseases.

A distinction may at once be drawn between inflammation of the conjunctiva resulting from the causes referred to and swelling of the lids arising out of injury. The symptoms in the former case are less sudden in their appearance, generally beginning with slight redness of the membrane and an increased secretion of tears. As the disease advances the discharge becomes thicker, and more or less opacity of the cornea may follow; the animal instinctively avoids exposure to a strong light, and the swelling of the eyelids becomes gradually more marked. The treatment of these cases will depend upon the stage which the disease has reached. If the inflammation is of the sub-acute or chronic form astringent lotions may be applied at once, and a weak solution of sulphate of zinc, two grains to the ounce of water, will be effective. It may be applied by gently pulling down the lower lid and dropping the fluid into the eye by means of a camel's-hair pencil.

When the affection is in the acute stage, a mild dose of physic should be given at the outset, and fomentations of warm water applied to the affected eyes, to be followed by an astringent lotion when the inflammation subsides. In cases where ophthalmia is connected with febrile disease - influenza for example - an important point is to place the animal where the eyes will not be irritated by too much light. The main treatment, however, should be directed to the cure of the systemic disease, and it may be that no local remedies will be needed.

The practice of bleeding from the eye-vein has for a long time been discontinued.

When ophthalmia assumes the purulent form it may be necessary to apply a more powerful astringent lotion, and a solution of nitrate of silver, three grains to the ounce of distilled water, is generally very effective in altering the character of the discharge, and in removing diphtheritic or granular deposit which sometimes accumulates on the surface of the membrane.