Can virtual reality simulation help to determine the importance of stereopsis in intraocular surgery?

Aim: To establish the effect of acute loss of stereopsis on simulated intraocular surgical performance.

Methods: This study was performed using the EYESi ophthalmic surgical simulator. Thirty junior doctors with no previous ophthalmic surgical experience were enrolled and distance visual acuity (Snellen), near visual acuity and stereoacuity (Frisby) were recorded. All participants completed a standard introductory programme on the forceps module to eliminate the learning curve. They then undertook four attempts of level 4 forceps module binocularly and another four monocularly to simulate an acute loss of stereopsis. Total score, odometer movement, corneal area injured, lens area injured and total time taken were recorded.

Results: Mean age was 31 years (SD±9). None had amblyopia, with all demonstrating distance visual acuity of 6/6 or better and N6 for near. Mean stereopsis was 35 s of arc (SD±18). Average total score decreased from 60 while operating binocularly to 47 monocularly (p<0.05). Average corneal area injured increased from 0.95 mm(2) to 2.30 mm(2) (p<0.05), average lens area injured increased from 1.76 mm(2) to 3.53 mm(2) (p<0.05) and average time taken increased from 69.6 s to 77.4 s (p<0.05).

Conclusion: The importance of stereopsis for intraocular surgery is difficult to establish in a live theatre setting without compromising patient safety. Virtual reality simulators provide a safe alternative. This study demonstrates a statistically significant decrease in simulated intraocular surgical performance with acute loss of stereopsis in potential ophthalmic training applicants. Caution is recommend in using these results to advocate stereopsis testing as a screening tool in interviews because some participants performed well despite an absence of stereopsis.