Hypotony after cataract extraction.

TREACHER COLLINS (1917), in his classical article on the sequelae of persistent hypotony, stated that the pathological changes in the ocular tissues were " brought about either from the relaxation of tissues usually kept taut or from altered conditions in the circulation ". Subsequent reports have only confirmed the accuracy of these observations. Within recent years the physiology of hypotony, especially the influence of neurogenic factors, has been investigated by many authors (Magitot, 1917, 1918; Schmidt and de Decker, 1930; Weekers, 1932; Kronfeld and Lin, 1937; Poos, 1952; Kronfeld, 1953), yet very little consideration has been given to the signs and symptoms produced by a continuing low ocular tension. In this paper the varying nature of both the symptoms and the complications of persistent hypotony will be emphasized. Experimental studies indicate that, although the posterior part of a limbal wound heals very slowly, a well-closed cataract incision is strong enough to withstand normal intra-ocular forces by the end of nine days (Yasuna, Ojers, Frayer, and Scheie, 1954; Gliedman and Karlson, 1955). Furthermore, it has been shown that when any rise in intra-ocular pressure occurs during the first week after operation aqueous humour will seep through the wound without disrupting it (Dunnington, 1955). The clinical appearance of such drainage is a boggy conjunctival flap throughout the entire length of the incision without evidence of hyphaema. Under normal conditions the oedema of the conjunctival flap disappears and union becomes firm by the end of 10 days. However, when healing is impaired, the aqueous humour continues to leak and the globe remains hypotonic. In as much as this drainage may be constant or intermittent, complete or incomplete, the accompanying signs and symptoms are not uniform. They are determined by the completeness and constancy of the loss of the anterior chamber. It is well, therefore, to subdivide the cases into the following two types, which differ greatly in onset, course, ,and clinical manifestations: