Purpose: To determine whether impaired or absent stereopsis affects the ability to perform simulated microsurgical tasks. Setting: University of Edinburgh, United Kingdom. Design: Prospective randomized cross-over study. Methods: Visual acuity and stereoacuity were measured. A band-pass filter was placed over the nondominant eye to reduce stereoacuity to 150 seconds of an arc (partial stereopsis), or the nondominant eye was completely occluded (absent stereopsis). Participants completed a computerized surgical simulator task 3 times with a randomized testing order (normal stereopsis, absent stereopsis, and partial stereopsis). The task involved using forceps to grasp and position objects in the anterior chamber. Outcomes included area of ocular injury, time to task completion, and overall score. Results: Ocular damage area was significantly worse with partial stereopsis (P = .002) and worse still when stereopsis was absent (P < .001 for normal vs absent stereopsis and P = .005 for partial vs absent stereopsis). The median ocular damage area was 3.55 mm2 (interquartile range [IQR], 1.21-5.88 mm2) with normal stereopsis, increasing to 6.10 mm2 (IQR, 3.96-12.47 mm2) with stereopsis reduced to 150 seconds of an arc and to 9.25 mm2 (IQR, 4.93-18.70 mm2) with no stereopsis. Time taken to complete the task increased and overall score decreased as stereopsis was reduced. The overall score decreased from 53% (IQR, 22.5-82%) under normal stereopsis to 0% (IQR, 0-43.5%) with absent stereopsis. Conclusions: Impaired stereopsis was associated with worse microsurgical performance, which may have implications for surgical training. The absence of stereopsis resulted in worse performance than partial reduction in stereopsis.

Genetic eye diseases, representing a wide spectrum of simple and complex conditions, are one of the leading causes of visual loss in children and working adults, and progress in the field has led to changes in disease investigation, diagnosis, and management. The past 15 years have seen the emergence of novel therapies for these previously untreatable conditions to the extent that we now have a licensed therapy for one form of genetic eye disease and many more in clinical trial. This is a systematic review of published and ongoing clinical trials of gene therapies for monogenic eye diseases. Databases of clinical trials and the published literature were searched for interventional studies of gene therapies for eye diseases. Standard methodological procedures were used to assess the relevance of search results. A total of 59 registered clinical trials are referenced, showing the significant level of interest in the potential for translation of these therapies from bench to bedside. The breadth of therapy design is encouraging, providing multiple possible therapeutic mechanisms. Some fundamental questions regarding gene therapy for genetic eye diseases remain, such as optimal dosing, the relative benefits of adeno-associated virus (AAV)–packaging and the potential for a significant inflammatory response to the therapy itself. As a result, despite the promise of the eye as a target, it has proven difficult to deliver clinically effective gene therapies to the eye. Despite setbacks, the licensing of Luxturna (voretigene neparvovec, Novartis) for the treatment of RPE65-mediated Leber congenital amaurosis (LCA) is a major advance in efforts to treat these rare, but devastating, causes of visual loss.