Measuring aniseikonia tolerance range for stereoacuity - a tool for the refractive surgeon.

OBJECTIVE: No method exists to measure aniseikonia tolerance in stereoacuity. The brain can compensate for 2%-3% aniseikonia (i.e. 2-3 dioptres of anisometropia) without impairing stereoacuity; however, a substantial proportion of anisometropic patients experience problems caused by disruptions of sensory fusion due to surgically induced aniseikonia. We hypothesized that individual differences in tolerance to aniseikonia exist and sought to develop a method to measure aniseikonia tolerance. METHODS: A total of 21 eye-healthy phakic individuals older than 50 years of age and 11 patients awaiting clear lens extraction were included. Patients were tested with best corrected near and distance visual acuity, cover/uncover test, eye dominance test, stereoacuity threshold (TNO test), slit lamp examination and ocular coherence tomography. The stereoacuity threshold was determined with aniseikonia induced by different size lenses ranging from 1% to 9% magnification of both eyes in increments of 1%. The aniseikonia tolerance range (ATR) was defined as the percentage aniseikonia in which the stereoacuity threshold was maintained. RESULTS: We examined 32 patients with a median age of 65 (95% CI: 62-66 years), CDVA better than 6/7.5 (0.1 logMAR), and median near visual acuity better than 6/6 (0.0 logMAR). The median stereoacuity threshold was 60 arcsec (maximum 30, minimum 120). We observed large inter-individual differences in ATR: 6/31 (19%) participants had an ATR of ≤1%, 1/31 (3%) had an ATR of 1-5%, 7/31 (22%) had an ATR of 5-10%, and 17/31 (54%) had an ATR of >10%. CONCLUSION: We present a reliable method for measuring the amount of aniseikonia that a person can tolerate without impairing stereopsis. We report large inter-individual differences in tolerance of aniseikonia.

Simulation of advanced cataract surgery - validation of a newly developed test.

PURPOSE: To develop and investigate an Eyesi simulator-based test for the more experienced cataract surgeon for evidence of validity. METHODS: The study was a prospective interventional cohort study and carried out at the Copenhagen Academy for Medical Education and Simulation. The Eyesi Simulator was used for the test which was developed by three expert cataract surgeons. Ten cataract surgeons (>250 surgeries performed) and ten ophthalmic residents performed two repetitions of the test. The test consisted of four modules: Iris Expansion Ring insertion - level 1, Iris Expansion Ring extraction - level 2, Capsulorhexis - level 3 and Anterior Vitrectomy - level 6. RESULTS: Internal consistency reliability showed Cronbach's alpha of 0.63. Test-retest reliabilities were significant for Iris Expansion Ring extraction - level 2 (p = 0.012) and Capsulorhexis - level 3 (p = 0.018). Differences between the two groups were only significant in both repetitions for the Iris Expansion Ring extraction - level 2 (p < 0.001 and p = 0.041, respectively). Furthermore, we found a statistically significant difference between the mean module scores for novices and the more experienced surgeons for Iris Expansion Ring insertion - level 1 (p = 0.021) and Capsulorhexis - level 3 (p = 0.019) in the first repetition. CONCLUSION: The investigated modules show evidence of validity within several aspects of Messick's framework. However, the evidence is not strong enough to apply the test for certification purposes of cataract surgeons, but the modules may still be relevant in the training of advanced cataract surgical procedures.

Correlation of virtual reality performance with real-life cataract surgery performance.

PURPOSE: To investigate the correlation between performance on a virtual reality simulator and real-life cataract surgical performance. SETTING: Nine ophthalmology departments in Denmark and Copenhagen Academy for Medical Education and Simulation, Copenhagen, Denmark. DESIGN: Prospective multicenter study. METHODS: Cataract surgeons with different experience levels were included. The participants performed 3 consecutive video-recorded phacoemulsification surgeries that were rated by masked raters using the Objective Structured Assessment of Cataract Surgical Skills (OSACSS) scoring system. Thereafter, the participants performed a previously validated test on an Eyesi virtual reality simulator. Primary outcomes were the mean OSACSS score from all 3 surgeries and the simulator score from the participants' first repetition of the performance test. RESULT: Nineteen surgeons participated. There was a statistically significant correlation between the simulator performance score and the mean OSACSS score across all experience levels, with a Pearson correlation of 0.65 (P = .003, R2 = 0.42). CONCLUSION: Simulator performance was significantly correlated with real-life cataract surgical performance.

Operating Room Performance Improves after Proficiency-Based Virtual Reality Cataract Surgery Training.

PURPOSE: To investigate the effect of virtual reality proficiency-based training on actual cataract surgery performance. The secondary purpose of the study was to define which surgeons benefit from virtual reality training. DESIGN: Multicenter masked clinical trial. PARTICIPANTS: Eighteen cataract surgeons with different levels of experience. METHODS: Cataract surgical training on a virtual reality simulator (EyeSi) until a proficiency-based test was passed. MAIN OUTCOME MEASURES: Technical performance in the operating room (OR) assessed by 3 independent, masked raters using a previously validated task-specific assessment tool for cataract surgery (Objective Structured Assessment of Cataract Surgical Skill). Three surgeries before and 3 surgeries after the virtual reality training were video-recorded, anonymized, and presented to the raters in random order. RESULTS: Novices (non-independently operating surgeons) and surgeons having performed fewer than 75 independent cataract surgeries showed significant improvements in the OR-32% and 38%, respectively-after virtual reality training (P = 0.008 and P = 0.018). More experienced cataract surgeons did not benefit from simulator training. The reliability of the assessments was high with a generalizability coefficient of 0.92 and 0.86 before and after the virtual reality training, respectively. CONCLUSIONS: Clinically relevant cataract surgical skills can be improved by proficiency-based training on a virtual reality simulator. Novices as well as surgeons with an intermediate level of experience showed improvement in OR performance score.

Simulation-based certification for cataract surgery.

PURPOSE: To evaluate the EyeSi(™) simulator in regard to assessing competence in cataract surgery. The primary objective was to explore all simulator metrics to establish a proficiency-based test with solid evidence. The secondary objective was to evaluate whether the skill assessment was specific to cataract surgery. METHODS: We included 26 ophthalmic trainees (no cataract surgery experience), 11 experienced cataract surgeons (>4000 cataract procedures) and five vitreoretinal surgeons. All subjects completed 13 different modules twice. Simulator metrics were used for the assessments. RESULTS: Total module score on seven of 13 modules showed significant discriminative ability between the novices and experienced cataract surgeons. The intermodule reliability coefficient was 0.76 (p < 0.001). A pass/fail level was defined from the total score on these seven modules using the contrasting-groups method. The test had an overall ability to discriminate between novices and experienced cataract surgeons, as 21 of 26 novices (81%) versus one of 11 experienced surgeons (9%) did not pass the test. The vitreoretinal surgeons scored significantly higher than the novices (p = 0.006), but not significantly lower than the experienced cataract surgeons (p = 0.32). CONCLUSION: We have established a performance test, consisting of seven modules on the EyeSi(™) simulator, which possess evidence of validity. The test is a useful and reliable tool for assessment of both cataract surgical and general microsurgical skills in vitro.

Endothelial cell loss and refractive predictability in femtosecond laser-assisted cataract surgery compared with conventional cataract surgery.

PURPOSE: To investigate the amount of endothelial cell loss (ECL) and refractive predictability by femtosecond laser-assisted cataract surgery (FLACS) compared to conventional phacoemulsification cataract surgery (CPS). METHODS: Forty-seven patients had one eye operated by FLACS and the contralateral eye operated by CPS (stop and chop technique). Both eyes had intraocular aspheric lenses implanted. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), central corneal endothelial cell count and hexagonality with a non-contact specular microscope were assessed preoperatively, 1-3 days postoperatively and 3 months postoperatively. RESULTS: Three days postoperatively, mean ECL was 249 cells/mm(2) (SD ± 744) (9.1%) by FLACS and 235 cells/mm(2) (SD ± 681) (8.2%) by CPS (p = 0.87). Three months postoperatively, mean ECL was 274 cells/mm(2) (SD ± 358) (11.4%) by FLACS compared with 333 cells/mm(2) (SD ± 422) (13.9%) by CPS, (p = 0.30) 3 months postoperatively, hexagonality was decreased by 1.8% (SD ± 30) by FLACS and by 1.4% (SD ± 13) by CPS, (p = 0.84). The mean absolute difference from the attempted refraction was 0.37 dioptres (D) (SD ± 0.33) by FLACS and 0.41 D (SD ± 0.42) by CPS (p = 0.56). Mean CDVA was 0.89 (0.3; 1.25) by FLACS and 0.93 (0.4; 1.25) by CPS at 3 months postoperatively (p = 0.36). Within both groups, 70% gained a CDVA of 6/6. Mean surgery time was 9.3 min (SD ± 1.9) by FLACS and 8.0 min (SD ± 1.9) by CPS, (p = 0.0018). Mean phaco energy was 3.78 U/S (SD ± 5.1) and 5.45 U/S (SD ± 4.6) (p < 0.0001) by FLACS and CPS, respectively. CONCLUSION: We found no significant difference in ECL and refractive predictability between FLACS and CPS 3 months postoperatively.

[Inadvertent instillation of superglue in both eyes should not be treated conservatively]. / Sammenlimning af begge øjne skal ikke behandles konservativt.

We describe a case of a 4-year-old boy who accidentally had both eyes glued together. The eyelashes were cut and the boy's eyelids were separated in general anaesthesia. When both eyes are glued together, we do not recommend expectancy, especially not in paediatric cases. For psychological reasons, the lids should be separated surgically. Furthermore, we suggest that similarities between ophthalmic bottles and superglue bottles are avoided so that future incidences may be avoided.