The Eye in Graves' Disease.

Classification "Lid lag" True lid lag is virtually specific for hyperthyroidism. It is probably due to increased tone in the levator palpebrae superioris and gives rise to the "staring" appearance. It can be elicited by making the subject follow movements of the finger rapidly up and down. The upper lid can Ibe observed to lag behind the movement of the eyeballs, especially in a downward direction, with the result that a line of sclera can be observed between the lid and the upper margin of the iris during this move'ment. It is commonly bilateral but may be much more marked in the one eye than the other. When this sign is more marked the upper lid may be permanently retracted so that even at rest a margin of sclera may be observed between the upper lid and the upper margin of the iris. This can be conveniently measured, especially in consecutive photographs. These signs usually disappear when the patient becomes euthyroid. The subsequent improvement in the appearance of the patient may give rise to the false impression that the other signs are progressing favourably (Dobyns, 1950).