Consolidating Approaches to Maximise Outcomes and Minimise Complications of Contemporary Cataract Surgery

Abstract

Cataract is an unavoidable age-change of the crystalline lens which progressively develops and causes visual impairment affecting millions worldwide. Cataract surgery with an intraocular lens, typically performed under local anaesthetic, transforms both vision and quality of life. This thesis explores several key aspects of contemporary cataract surgery, which is the most commonly performed surgical procedure in the world. The New Zealand Cataract Risk Stratification system (NZCRS) was refined and used in a major prospective study (N=512 cases) of cataract surgery in a teaching hospital setting (NZCRS IV). This revealed excellent adherence to the system in Auckland District Health Board (ADHB) and the refined system maintained a reduced complication rate compared to prior non-stratification phase (Auckland Cataract Studies). To evaluate the effectiveness of sub-Tenon’s block (STB) regional anaesthesia in cataract surgery, the prospective data from NZCRS IV were combined with similar prospective cohort studies previously conducted in ADHB (NZCRS I-III) (N=2,000). Patient age and nurse-administered STB positively influenced patient intraoperative control of head movement, eye movement, and analgesia - which were also identified as risk factors for intraoperative complications. A parallel retrospective study assessed the effectiveness of cataract surgery with toric intraocular lenses to correct corneal astigmatism (N=200 eyes). This study revealed excellent visual outcomes and low residual refractive astigmatism. To assess relative dexterity in eye surgery the Eyesi® Surgical virtual reality simulator was used to evaluate the dominant hand (DH) and non-dominant hand (NDH) of medical and non-medical participants. Predictors for DH and NDH dexterity were identified that may help surgical training schemes develop appropriate training programs to improve surgical skills. Finally, to evaluate the effect of improved cataract surgery and other factors on corneal transplantation rates, analysis of the prospective New Zealand National Eye Bank database (1991-2020) was performed (N=6840). This revealed that transplantation for pseudophakic bullous keratopathy (a long-term complication of cataract surgery) is declining, highlighting improved long term cataract surgery outcomes. Together these five interrelated studies provide new data on all aspects of cataract surgery from training surgeons, predicting and reducing intraoperative complications, evaluating visual outcomes, and assessing long-term trends in postoperative complications.