"No. I suppose inflammation of the eyes—the iris."
"Precisely. Now, just because you're a woman of intelligence I'm going to try to give you a little explanation of your trouble, so you will know what you are facing."
"I wish you would."
"Very well. Now, you must think of the eye as a lens, but one made up of cells, of tissues. It can know inflammation. As a result of many inflammations there is what we call an exudation—a liquid passes from the tissues. This may be thin or serum-like, or it may be heavier, something like granulations. The tissues are weak—they exude something in their distress, in their attempt to correct this condition when they have been inflamed.
"The pupil of your eye is the aperture, the stop of the lens. That is the hole through which the light passes. Around it lie the tissues of the iris. In the back of the eye is the retina, which acts as a film for the eye's picture.
"Now, it was the part of the eye around that opening which got inflamed and began to exude. Such inflammation may come from eye-strain, sometimes from glare like furnace heat, or the reflection of the sun on the snow. Snow-blindness is sometimes painful. Why? Iritis.
"In any case, a chronic irritation came into your case some time. Little by little there came a heavy exudation around the edges of the inflamed iris. It was so heavy that we call it a 'plastic' exudation. Now, that was what was the technical trouble of your eye—plastic exudation.
"This exudation, or growth, as we might call it, went on from the edges of the iris until it met in the middle of the pupil. Then there was spread across the aperture of your lens an opaque granulated curtain through which light could not pass. Therefore you could not see. The plastic exudation had done its evil work as the result of the iritis—that is to say, of the sufferings of the iris."
"I begin to understand," said Mary Gage. "That covers what seemed to happen."
"It covers it precisely, for that is precisely what did happen. It was not cataract. I knew, or thought I knew, that it was not from retinal scars due to inflammation in the back of the eye. It was just a filling up of the opening of the eye.