Pretraining of basic skills on a virtual reality vitreoretinal simulator: A waste of time.

PURPOSE: To investigate whether pretraining of basic skills in virtual vitreoretinal surgery affected the performance curve when proceeding to procedure-specific modules. METHODS: This study was a prospective, randomized, controlled, two-centre study. Medical students were randomized into two groups: Group 1 pretrained basic psycho-motor skills (Navigation Training level 2 and Bimanual Training level 3) until they reached their performance curve plateau. Hereafter, both groups trained on the procedure-specific modules (Posterior Hyaloid level 3 and ILM Peeling level 3) until they reached their performance curve plateau. Plateau was defined as three consecutive sessions with the same score with an acceptable variation. The primary outcome was time used to reach performance curve plateau in the procedure-specific modules. RESULTS: A total of 68 medical students were included, and equally randomized into two groups. The participants in Group 1 used a median time of 88 minutes to reach plateau in the basic skills modules but did not differ from Group 2 in time to reach plateau on the procedure-specific modules (183 min versus 210 min, p = 0.40) or in the amplitude of plateau. Group 1 and 2 differed significantly in the starting score of ILM peeling level 3 (0 (0-0) versus 3.5 (0-75), p = 0.03). CONCLUSION: We were not able to show positive skill transfer from basic skills training to the procedure-specific modules in time, starting score or amplitude of plateau. Thus, we recommend that aspiring vitreoretinal surgeons proceed directly to simulation-based training of procedures instead of spending valuable training time on basic skills training.

Loss of retinal tension and permanent decrease in retinal function: a new porcine model of rhegmatogenous retinal detachment.

PURPOSE: Permanent loss of visual function after rhegmatogenous retinal detachment can occur despite successful surgical reattachment in humans. New treatment modalities could be explored in a detachment model with loss of retinal function. In previous porcine models, retinal function has returned after reattachment, regardless of height and duration of detachment. Difference in retinal tension between the models and the disease might explain these different outcomes. This study investigates, for the first time in an in vivo porcine model, another characteristic of rhegmatogenous retinal detachment - the loss of retinal tension. METHODS: Left eyes (n = 12) of 3-month-old domestic pigs were included. Baseline multifocal electroretinogram (mfERG) and a fundus photograph were obtained following anaesthesia (isoflurane). The pigs were vitrectomized, saline was injected subretinally, and the RPE was removed. The eyes were evaluated at 2, 4 and 6 weeks after surgery. Four eyes were enucleated at each evaluation for histologic examinations. RESULTS: A retinal detachment structurally resembling rhegmatogenous retinal detachment was induced in 11 out of 12 pigs. MfERG amplitudes were significantly decreased despite partial reattachment four and 6 weeks after detachment. The retinal thickness decreased with 27%, the inner nuclear layer degenerated, Müller cells hypertrophied, and outer segments were lost. In the ganglion cell layer, cellularity increased and there was cytoplasmic staining with Cyclin D1. Vimentin and GFAP staining for glial cells increased. After 2 weeks of detachment, the ganglion cells had lost their nucleus and nucleolus. CONCLUSIONS: Loss of retinal tension in the detached retina seems to induce permanent damage with loss of retinal function. Death of ganglion cells, observed as soon as 2 weeks after detachment, explains the permanent loss of retinal function. The new model enables investigations of time-relationship between retinal detachment and lasting damage in addition to exploration of novel treatment modalities.

High correlation between performance on a virtual-reality simulator and real-life cataract surgery.

PURPOSE: To investigate the correlation in performance of cataract surgery between a virtual-reality simulator and real-life surgery using two objective assessment tools with evidence of validity. METHODS: Cataract surgeons with varying levels of experience were included in the study. All participants performed and videorecorded three standard cataract surgeries before completing a proficiency-based test on the EyeSi virtual-reality simulator. Standard cataract surgeries were defined as: (1) surgery performed under local anaesthesia, (2) patient age >60 years, and (3) visual acuity >1/60 preoperatively. A motion-tracking score was calculated by multiplying average path length and average number of movements from the three real-life surgical videos of full procedures. The EyeSi test consisted of five abstract and two procedural modules: intracapsular navigation, antitremor training, intracapsular antitremor training, forceps training, bimanual training, capsulorhexis and phaco divide and conquer. RESULTS: Eleven surgeons were enrolled. After a designated warm-up period, the proficiency-based test on the EyeSi simulator was strongly correlated to real-life performance measured by motion-tracking software of cataract surgical videos with a Pearson correlation coefficient of -0.70 (p = 0.017). CONCLUSION: Performance on the EyeSi simulator is significantly and highly correlated to real-life surgical performance. However, it is recommended that performance assessments are made using multiple data sources.

Effect of glial cell line-derived neurotrophic factor on retinal function after experimental branch retinal vein occlusion.

PURPOSE: The objective of the study was to investigate the effect of glial cell line-derived neurotrophic factor (GDNF) on the multifocal electroretinogram (mfERG) following an induced branch retinal vein occlusion (BRVO) in pigs. METHODS: Electrophysiological examination of the retina was performed in 20 pigs with standard and four-frame mfERG 4 weeks after induced BRVO and intravitreal injection of GDNF or vehicle. BRVO was induced by intraocular diathermia of the superior retinal vein. Inner retinal function was measured by analysis of the four-frame mfERG (iN1) and outer retinal function with standard mfERG (P1). RESULTS: In GDNF-treated BRVO eyes, P1 and iN1 amplitudes (P = 0.51 and 0.78) or implicit times (P = 0.08 and 0.99) did not differ from those in healthy fellow eyes. After vehicle injection, P1 and iN1 amplitudes of BRVO eyes were significantly lower than in the healthy fellow eye (P = 0.022 and 0.013). The log ratios of mfERG amplitudes between experimental and healthy fellow eyes were calculated (BRVO/healthy). GDNF improved the ratios of the four-frame mfERG (1.29 [0.88-1.88]) compared with vehicle (0.32 [0.21-0.50], P < 0.001). Equally, GDNF improved the ratios of the standard mfERG; GDNF (0.75 [0.51-1.10]) and vehicle (0.42 [0.27-0.63], P = 0.048). CONCLUSIONS: GDNF appears neuroprotective on retinal electrophysiological function after BRVO. The efficacy and safety of GDNF remain to be investigated in primate eyes.