Perimetric and angiographic effects of retinotomy

Aim: We sought to characterise the morphological and functional effects of drainage retinotomy on the vascular, neural, subretinal and epiretinal components of the affected retina. Patients and methods: Following successful retinal reattachment surgery involving drainage retinotomy in 15 cases (retinotomy group) and no retinotomy in 14 cases (control group), the existence, nature and quadrantic area of visual field loss to a white III4e target was determined using kinetic Goldmann perimetry. Vascular alterations were characterised using fluorescein angiography with peripheral sequences. Results: Visual field defects within 30 degrees of fixation were present in 12 of 14 (86%) of the retinotomy group (including ail eyes in which the retinotomy was sited within five disc diameters of fixation) and none of the control group (Fisher exact test, P=0.00005). Following superonasal retinotomy, inferotemporal field area (median area 82 units, range 44 to 128) was approximately half that following superotemporal retinotomy (median area 167 units, range 119 to 192) (Wilcoxon's ranksum P=0.003). No vascular abnormalities distal to the retinotomy were identified, although subretinal neovascularisation (two eyes) and epiretinal membrane formation (one eye) occurred at the retinotomy site. Conclusion: We recommend that where possible subretinal fluid be drained via existing breaks, and if retinotomy is necessary, that it should be sited more than five disc diameters from fixation in the superotemporal quadrant to minimise visual field loss.