The Effect Of Intraocular Pressure During Phacoemulsification In Patients With Diabetic Retinopathy And Glaucoma; A Randomised Controlled Feasibility Trial

The Centurion Vision System combined with Active Sentry Handpiece (Alcon Laboratories, USA) has considerably reduced surge and enabled surgeons to operate with lower intraocular pressure (IOP) levels than was previously possible. It is not known if low IOP settings improve the outcomes or efficiency of surgery, as compared to higher IOP settings, particularly in patients with diabetic retinopathy or glaucoma, where the effects of the strategy are likely to be of greatest benefit.

Routine phacoemulsification surgery performed by three experienced surgeons in a specialist ophthalmology centre in the United Kingdom.

Masked observer randomised cotrolled feasibility trial of a low (30mmHg) infusion pressure as compared to a standard pressure (60mmHg) during phacoemulsification in patients with either diabetic retinopathy or glaucoma. All other surgical settings were matched between the groups. The primary endpoint was the CDE, measured in percent-seconds, i.e. the total energy dissipated during phacoemulsification. A wide range of exploratory parameters were investigated including surgical metrics, anterior segment optical coherence tomography (OCT) angiography (OCTA), or retinal nerve fibre layer using spectral domain OCT were also assessed. Variables were measured at baseline, and postoperative days 1, 21 and 40.

70 eyes of 70 patients underwent surgery and were analysed. 37 were randomised to the standard infusion and 33 to the low. There were 41 patients (21 standard and 20 low) with diabetic retinopathy and 29 (16 standard and 13 low) with glaucoma. The groups were well matched for all baseline features. There were no operative complications. No significant difference between the two pressure groups for CDE used [6.5 (SD 3.6) versus 6.1 (SD 3.4)], p=0.68, or other surgical metrics. There were no significant differences in any of the postoperative variables. There was a significant reduction in the foveal avascular zone area and perimeter on OCTA in the standard infusion group at day 21 but not in the low infusion group (p=0.04 and 0.03).  

Surgery was successfully carried out with the lower IOP settings without any loss in surgical efficiency, increase in operative complications or worsening of postoperative outcomes.