DISEASES OF THE CORNEA 105 



drawn tightly and tied, and the whole covered by the 

 conjunctiva by tightening and tying the puckering 

 threads. The excision should be performed so as to get 

 a transverse closure and as near the center as possible, 

 to avoid irritation in the act of winking. 



Keratectasia is a protrusion of the cornea following 

 a keratitis without perforation, though the cornea has 

 become thin by destruction of the superficial layers 

 and offers httle resistance to intra-ocular pressure. 

 It differs from a staphyloma in that the iris is not 



involved. 



An incision through the cornea at the margin, followed 

 by a compress bandage, is of value, though if tension 

 persists an iridectomy should be done, not to reduce the 

 tension alone, but for visual purposes as well. 



Keratoconus, or conic cornea, resembles keratecta- 

 sia in some respects. It is not due to an inflammatory 

 process, however, and does not become opacified. It 

 is caused by a thinness of the corneal layers which 

 yield readily to the pressure within the globe, causing 

 the cornea to assume a clear cone shape. 



Keratoglobus, also called hydrophthalmus and buph- 

 thalmus (ox eye) .-In this case there is not a protru- 

 sion of the cornea alone, as in the preceding diseases, 

 but rather an enlargement of the cornea in keeping 

 with the general enlargement of the globe. It is con- 

 genital, as a rule, or appears in early life, and is said 

 to be analogous to glaucoma in later life. The coats 



