INTRAOPERATIVE INTRAOCULAR PRESSURE CHANGES DURING PHACOEMULSIFICATION IN PATIENTS WITH DIABETIC RETINOPATHY OR GLAUCOMA: A RANDOMIZED CONTROLLED FEASIBILITY TRIAL IN PAKISTAN
Keywords:
Phacoemulsification; intraocular pressure; diabetic retinopathy; glaucoma; complications; surgical efficiency; PakistanAbstract
Purpose. To determine whether lowering the infusion pressure during phacoemulsification, using the Centurion Vision System with Active Sentry handpiece, changes surgical efficiency, complication rates, or a range of clinical and imaging measures, compared with the higher pressures conventionally used in patients who have cataract together with diabetic retinopathy or glaucoma.
Setting. A tertiary eye centre in Islamabad, Pakistan.
Design. Randomized, observer-masked feasibility trial.
Methods. Patients with cataract and either diabetic retinopathy or primary open-angle glaucoma (any severity) were randomly assigned to an infusion pressure of 30 mmHg (LOW) or 60 mmHg (HIGH). All other fluidic settings were held constant. Surgical metrics, clinical measures and imaging were recorded before surgery and on days 1, 18 and 36 afterwards.
Results. Eighty three eyes of 83 patients (45 with diabetic retinopathy, 38 with glaucoma) were operated on and followed to completion. Cumulative dissipated energy (CDE) did not differ between groups (mean 6.5 percent-seconds in HIGH vs 6.5 in LOW; p = 0.65), nor did any other surgical metric. No posterior capsule rupture or other intraoperative complication occurred. The proportion of eyes with raised IOP on day 1 was similar between groups. Slit-lamp-visible corneal oedema on day 1 was seen in 7 LOW-group patients (23.2%) and 6 HIGH-group patients (15.3%), and had resolved in all by day 18.
Visual acuity, IOP, corneal thickness and optical coherence tomography (OCT) measures did not differ between groups at any time point. However, on OCT angiography, the foveal avascular zone (FAZ) perimeter and area at day 18 were significantly smaller (relative to baseline) in the HIGH group than in the LOW group (p = 0.04 and 0.06), with a matching rise in superficial vascular plexus density (p = 0.04).
Conclusion. Operating at 30 mmHg, with aspiration settings kept identical, was not less efficient and did not raise complication rates relative to 60 mmHg. Lower pressure appeared to provoke fewer short-term changes in the retinal microvasculature; the long-term meaning of this is unknown.
