III.—On Hemiopsy, or Half-Vision

Extract

The affection of Half-vision, or Half-blindness as it has been called, was first distinctly described by Dr Wollaston, in a paper “On Semidecussation of the Optic Nerves,” published in the Philosophical Transactions for 1824. “It is now more than twenty years,” he says, “since I was first affected with this peculiar state of vision, in consequence of violent exercise I had taken for two or three hours before. I suddenly found that I could see but half the face of a man whom I met, and it was the same with every object I looked at. In attempting to read the name Johnson over a door, I saw only son, the commencement of the name being wholly obliterated from my view. In this instance, the loss of sight was towards my left, and was the same, whether I looked with my right eye or my left. This blindness was not so complete as to amount to absolute blackness, but was a shaded darkness, without definite outline. The complaint lasted only about a quarter of an hour.” In 1822, Dr Wollaston had another attack of hemiopsy, with this difference, that the blindness was to the right of the centre of vision, and he has referred to three other cases among his friends; but in these, the affection was accompanied with headache and indigestion.