The Auckland cataract study: co-morbidity, surgical techniques, and clinical outcomes in a public hospital service

To prospectively assess cataract surgery in a major New Zealand public hospital by defining presenting clinical parameters and surgical and clinical outcomes in a cohort of subjects just below threshold for treatment, based upon a points based prioritisation system.

The prospective observational study comprised 488 eyes of 480 subjects undergoing consecutive cataract operations at Auckland Hospital. All subjects underwent extensive ophthalmic examination before and after surgery. Details of the surgical procedure, including any intraoperative difficulties or complications, were documented. Postoperative review was performed at 1 day and 4 weeks after surgery. Demographic data, clinical outcomes, and adverse events were correlated by an independent assessor.

The mean age at surgery was 74.9 (SD 9.6) years with a female predominance (62%). Significant systemic disease affected 80% of subjects, with 20% of the overall cohort exhibiting diabetes mellitus. 26% of eyes exhibited coexisting ocular disease and in 7.6% this affected best spectacle corrected visual acuity (BSCVA). A mean spherical equivalent of -0.49 (1.03) D and mean BSCVA of 0.9 (0.6) log MAR units (Snellen equivalent approximately 6/48) was noted preoperatively. Local anaesthesia was employed in 99.8% of subjects (94.9% sub-Tenon's). The majority of procedures (97.3%) were small incision phacoemulsification with foldable lens implant. Complications included: 4.9% posterior capsule tears, 3.8% cystoid macular oedema, and one case (0.2%) of endophthalmitis. Mean BSCVA after surgery was 0.1 (0.2) log MAR units (6/7.5 Snellen equivalent), with a mean spherical equivalent of -0.46 (0.89) D, and was 6/12 or better in 88% of all eyes. A drop in BSCVA, thought to be directly attributable to the surgical intervention, was recorded in a small percentage of eyes (1.5%) after surgery.

This study provides a representative assessment of the management of cataract in the New Zealand public hospital system. A predominantly elderly, female population, frequently exhibiting significant systemic illness and coexisting ocular disease, relatively advanced cataracts, and poor BSCVA, presented for cataract surgery. The majority of subjects underwent small incision, phacoemulsification, day case surgery. While almost 90% achieved at least 6/12 BSCVA post-surgery, approximately 5% sustained an adverse intraoperative event and 1.5% of eyes exhibited a reduction in BSCVA postoperatively.