Preliminary evaluation of the VIsion PERformance(VIPER) simulator

Background:This study evaluated the VIsion PERformance(VIPER)simulator’s ability to assess the functional visual performance in warfighters conducting civilian and military tasks.Methods:Thirty service members,aged 25–35 years old with a best corrected distance visual acuity(VA)better than or equal to 20/20 or logarithm of the minimum angle of resolution(logMAR)0.00,were randomized to locate and identify road signs and mock improvised explosive devices(IEDs)under either daytime conditions or with infrared imagery,with(cc)and without(sc)wearing their habitual correction.Participants also underwent binocular uncorrected(UDVA)and corrected(CDVA)visual assessment,refraction,contrast sensitivity testing and wavefront aberrometry.Results:The mean age was 28.47 years.The manifest spherical equivalent was–3.16±1.75 diopters(D),the UDVA in both eyes(OU)was logMAR 0.83±0.47,and the CDVA OU was–0.11±0.06.For VIPER,the mean difference in the detection distance(DD)for road signs ccDD vs.scDD was(76.7±52.8)m(P<0.001).The average difference in identification distance(ID)ccID vs.scID was(13.9±6.3)m(P<0.001).The mean accuracies were 83.5%and 27.9%for cc and sc,respectively(P<0.001).The regression analysis indicated that a 1.6 m change in the distance accounts for a 1%change in the accuracy(P=0.002).Without correction,a 4.1 m change accounts for a 1%change in the accuracy(P<0.001).The average IED ccDD was(29.9±8.2)m,and that for scDD was(13.2±13.6)m(P<0.001).The average IED ccID was(32.2±6.2)m and that for the scID was(7.4±10.3)m(P<0.001).The mean IED identification accuracy was 46.7 and 11.4%for cc and sc,respectively(P<0.001).Conclusions:The preliminary results reflect VIPER’s ability to assess functional visual performance when detecting and identifying signs and IEDs.Furthermore,VIPER is able to detect performance changes with and without correction.

Wavefront-optimized surface retreatments of refractive error following previous laser refractive surgery: a retrospective study

Background:Retreatments are sometimes necessary to correct residual or induced refractive errors following refractive surgery.Many different combinations of primary treatment methods and retreatment techniques have been studied,however,few studies have investigated wavefront-optimized(WFO)technology for retreatment following primary refractive surgery.This study aimed to report the outcomes of WFO photorefractive keratectomy(PRK)retreatments of refractive error following previous laser refractive surgery with PRK,laser in situ keratomileusis(LASIK),or laser-assisted subepithelial keratectomy(LASEK).Methods:We reviewed records of patients who underwent WFO PRK retreatments using the Allegretto Wave Eye-Q 400 Hz Excimer Laser System(Alcon Surgical)between January 2008 and April 2011 at Walter Reed Army Medical Center and Madigan Army Medical Center.Outcomes were recorded in terms of uncorrected distance visual acuity(UDVA),manifest refraction spherical equivalent(MRSE),corrected distance visual acuity(CDVA),and complications at 1 month(M),3 M,and 6 M post-op.Results:Seventy-eight patients(120 eyes)underwent WFO PRK retreatment during the study period.Primary surgery was surface ablation in 87 eyes(78 PRK,9 LASEK)and LASIK in 33 eyes.The mean spherical equivalent before retreatment was−0.79±0.94 D(−3.00 to 1.88 D).UDVA was≥20/20 in 69 eyes(60.0%)at 1 M,54 eyes(71.1%)at 3 M,and 27 eyes(73.0%)at 6 M follow-up.MRSE was within±0.50 D of emmetropia in 78 eyes(67.8%)at 1 M,59 eyes(77.6%)at 3 M,and 25 eyes(67.6%)at 6 M follow-up.CDVA was maintained within±1 line of pre-op in 113 of 115 eyes(98.3%)at 1 M,74 of 76 eyes(97.4%)at 3 M,and 37 eyes(100%)at 6 M follow-up.Conclusion:Although follow-up was limited beyond 3 M,WFO PRK retreatments in patients with residual refractive error may be a safe and effective procedure.Further studies are necessary to determine the long-term safety and stability of outcomes.