Inversion of the lid, from contraction of a cicatrix in the conjunctiva, may be counteracted, by destroying with caustic, or removing with cutting instruments, a portion of the outer integuments, corresponding to the internal cicatrix. Forceps with broad points are used for taking up a fold of the skin, and an oval portion is then excised with a knife or scissors, cutting instruments being less painful and more precise than caustics. Of the latter, the sulphuric acid has been particularly recommended for this purpose. The contraction of the wound releases the cilia from the power of the internal cicatrix, and the parts are restored to their healthy state. [Illustration] The term _Pterygium_ is employed to denote a thickened and vascular state of part of the conjunctiva. The diseased portion is generally of a triangular form, commencing at the inner corner of the eye, extending towards the cornea, gradually diminishing in breadth, and terminating in a sharp apex, either at the margin of the cornea, or somewhere between its margin and centre. The thickening is seldom great, but the vessels which traverse the thickened part are numerous, enlarged, and tortuous—are, in fact, varicose. The base of the pterygium is always on the circumference of the eye, generally at the inner corner, and its apex is seldom, if ever, situated beyond the centre of the cornea: frequently the sclerotic conjunctiva alone is affected. The motions of the eye are little disturbed by the disease, but vision is materially impaired when a considerable part of the cornea is covered. Pterygium is in general single, but sometimes, though very rarely, there are two or more pterygia in one eye; and, in such cases, the patient’s vision is seriously affected, in consequence of the apices of the different pterygia uniting and coalescing on the cornea, and investing the greater part of that organ with a thick and dark shade. When several occur, they sometimes unite throughout their whole extent, and cover the half or more of the eye. This disease is very common amongst negroes and persons residing in equatorial climates.