Drainage of subretinal fluid: why, when, where and how.

The release of subretinal fluid is only required in certain complicated types of retinal detachment and should be avoided when possible. An important consideration in releasing subretinal fluid is the timing of this step in relation to the application of diathermy or cryotherapy as the primary treatment modality. Drainage should precede application of cryotherapy but follow the use of diathermy. The most satisfactory site for drainage is either immediately above or below the medial or lateral long ciliary nerve, just posterior to the equator of the globe. A technique for drainage of subretinal fluid has been developed and evaluated. An 'L'-shaped scleral flap is dissected to produce a relatively staphylomatous zone and the choroid is perforated near its center.