This affection is characterized by pain in the eye so severe as to prevent sleep. The pain also extends to the brow and the temples, in consequence of which it is often mistaken for neuralgia. The eye is congested, especially about the cornea. The lids are likely to be swollen and puffy. There is at first a sensation of burning and itching in the eye, but the pain shortly becomes much more severe, being sharp and cutting. The pain is worse during the night, diminishing toward the morning. There is some feverishness, coated tongue, want of appetite, and often nausea and vomiting, so that the affection is sometimes mistaken for a bilious attack. Iritis, may also be regarded as a simple cold in the eye at first, an error which may result in loss of the sight by occasioning neglect. A symptom of very great importance is contraction of the pupil. The pupil generally contracts promptly when exposed to a strong light, and dilates when the light is withdrawn. If the pupil is contracted and remains so, whether exposed to strong light or not, or if it moves very slowly, there being at the same time great sensitiveness to light, inflammation of the iris may be very strongly suspected. An excellent test is to drop into the eye two or three drops of a solution of atropia, two or three grains to the ounce of water. The effect of this treatment is to dilate the pupil. If the pupil is found greatly enlarged fifteen or twenty minutes after the application of the atropia, the iris is probably not affected. The most common causes of iritis are rheumatism and syphilis, which may result from overuse of the eyes, from sympathetic irritation with another eye which has been the seat of injury, or from direct injury.