To Drain or Not to Drain? The Manchester Buckle Study

PURPOSE: To assess whether external drainage of subretinal fluid (SRF) improves anatomical or visual outcomes in scleral buckle surgery for rhegmatogenous retinal detachment (RRD). METHODS: Retrospective review of 609 primary scleral buckles performed at Manchester Royal Eye Hospital (2008-2023). Pre/intra-operative characteristics, drainage use, best-corrected visual acuity (BCVA) and single-surgery anatomical success (SSAS) were analysed. RESULTS: 428 patients without SRF drainage and 181 with drainage were included. Groups were similar for age (p=0.33), preoperative BCVA (p=0.47), RRD type (dialysis vs. retinal hole, p=0.17), high myopia (p=0.52) and trauma (p=0.06). Drainage group had more macula-off RRDs (48 % vs 39 %, p=0.05) and were more often operated on by consultants (p<0.01). SSAS rates were 86.7 % with drainage and 83.6 % without (p=0.67). Final BCVA also showed no difference in all (p=0.47); macula-on (p=1.00); and macula-off eyes (p=0.17). After adjusting for age, high myopia, trauma, type of RRD, macula status, surgeon grade, external SRF drainage was not independently associated with either SSAS (OR=1.39, 95% CI 0.81-2.36, p=0.23) or postoperative BCVA (B= -0.023, 95% CI -0.093 to 0.048, p=0.532). Drainage caused subretinal haemorrhage in 34 eyes (18.8 %), almost all (32) small and localised to the drainage site; no endophthalmitis, retinal incarceration or vitreous loss occurred. CONCLUSIONS: External SRF drainage during scleral buckling is safe but did not improve SSAS or BCVA. Its use should remain individualized based on RRD characteristics and surgeon preference.