It is well known that in cases of rhegmatogenous * retinal detachment1the ocular tension does not remain at its normal level. Fresh retinal detachments generally show a certain degree of ocular hypotony, whereas long-standing cases may have a tendency toward glaucoma. Surgical reattachment of the retina is also followed by a change of the ocular tension, which is low immediately after a successful operation and rises gradually to a normal level during the ensuing weeks or months. The mechanisms of tension changes associated with rhegmatogenous retinal detachment are not well understood. In addition, the effects on the ocular tension of surgical procedures for reattachment of the retina have not been investigated in detail. In this respect, it is sometimes felt that surgical procedures which markedly modify the shape of the globe may influence the ocular pressure to a greater degree than simple diathermy procedures. The purpose of this series