Randomized dose-response analysis of mitomycin-C to prevent haze after photorefractive keratectomy for high myopia.

PURPOSE: To evaluate the safety and efficacy of mitomycin-C (MMC) 0.01% (0.1 mg/mL) in preventing haze formation after wavefront-guided photorefractive keratectomy (PRK) for higher myopia at 3 exposures. SETTING: United States Navy Refractive Surgery Center, San Diego, California, USA. DESIGN: Double-masked randomized prospective trial. METHODS: Sixty-, 30-, and 15-second exposures of MMC 0.01% were compared in wavefront-guided PRK for higher myopia. One eye received MMC (surgical sponge) and the other a placebo. All eyes received a 4-month tapering postoperative topical steroid regimen. Endothelial cell densities, haze scores, high- and low-contrast acuities, and manifest refraction were measured preoperatively and 1, 3, 6, and 12 months postoperatively. Outcomes were analyzed as repeated measures over time. RESULTS: The mean preoperative manifest refraction spherical equivalent was -5.98 diopters (D) (range -4.4 to -8.0 D). No eye developed more than trace haze. There was a significant difference in haze scores between MMC-treated eyes and untreated eyes at 1 and 3 months (P=.034) but no difference at 6 and 12 months. Endothelial cell densities decreased in the treated eyes and untreated eyes at all 3 exposures at 1 month but returned to baseline by 6 months. There was no difference in acuities or refractions with or without MMC. CONCLUSIONS: Mitomycin-C may not be needed to prevent haze after modern PRK with a 4-month steroid taper. There was no clinically significant difference in haze formation between MMC eyes and control eyes at the concentration and exposures used.

Night driving simulation in a randomized prospective comparison of Visian toric implantable collamer lens and conventional PRK for moderate to high myopic astigmatism.

PURPOSE: To compare changes in simulated night driving performance after Visian Toric Implantable Collamer Lens (TICL; STAAR Surgical) implantation and photorefractive keratectomy (PRK) for the correction of moderate to high myopic astigmatism. METHODS: This prospective, randomized study consisted of 43 eyes implanted with the TICL (20 bilateral cases) and 45 eyes receiving conventional PRK (VISX Star S3 excimer laser) with mitomycin C (22 bilateral cases) for moderate to high myopia (-6.00 to -20.00 diopters[D] sphere) measured at the spectacle plane and 1.00 to 4.00 D of astigmatism. As a substudy, 27 eyes of 14 TICL patients and 41 eyes of 21 PRK patients underwent a simulated night driving test. The detection and identification distances of road signs and hazards with the Night Driving Simulator (Vision Sciences Research Corp) were measured with and without a glare source before and 6 months after each procedure. RESULTS: No significant difference was noted in the pre- to postoperative Night Driving Simulator in detection distances with and without the glare source between the TICL and PRK groups. The differences in identification distances without glare were significantly better for business and traffic road signs and pedestrian hazards in the TICL group relative to the PRK group whereas with glare, only the pedestrian hazards were significantly better. A clinically relevant change of Night Driving Simulator performance (>0.5 seconds change in ability to identify tasks postoperatively) was significantly better in the TICL group (with and without glare) for all identification tasks. CONCLUSIONS: The TICL performed better than conventional PRK in the pre- to postoperative Night Driving Simulator testing with and without a glare source present.

Comparison of night driving performance after wavefront-guided and conventional LASIK for moderate myopia.

PURPOSE: To compare preoperative and postoperative changes in simulated night driving performance after wavefront-guided (wLASIK) and conventional LASIK (cLASIK) for the treatment of moderate myopia. DESIGN: Retrospective, comparative study. PARTICIPANTS: All eyes of subjects with a preoperative manifest spherical equivalent (MSE) between -4.50 and -6.00 who underwent night driving simulator (NDS) testing from 2 clinical trials were entered into the study. This comprised 38 cLASIK patients (62 eyes; mean -5.46 diopters [D] MSE) and 21 wLASIK patients (36 eyes, mean -5.20 D MSE). METHODS: Patients' records were reviewed from 2 LASIK clinical trials that had similar enrollment criteria. One trial treated patients with conventional LASIK using a bladed microkeratome (cLASIK) and the other treated with a wavefront-guided profile using a femtosecond laser (wLASIK). In both trials, patients with moderate myopia were asked to participate in NDS testing. MAIN OUTCOME MEASURES: The detection and identification distances of road hazards were measured with and without a glare source before and 6 months after LASIK. Each eye was tested independently in best-corrected trial frames by a masked operator. RESULTS: In every category, there was a mean reduction in the preoperative to postoperative NDS performance after cLASIK (mean change, -21.3 to -27.9 ft, -6.5 to -8.5 m; 95% confidence interval [CI], -12.0 to -41.3 ft, -3.7 to -12.6 m); there was a corresponding mean improvement after wLASIK (mean change +15.0 to +29.1 ft, +4.6 to +8.9 m; 95% CI, +8.3 to +41.5 ft, +2.5 to +12.6 m). Significant differences between cLASIK and wLASIK NDS performance was observed in every category (P<0.;01, Tukey's honest significant difference for unequal numbers). A clinical relevant loss of NDS performance (>0.5 seconds) was observed in 32% to 38% of cLASIK eyes for all tasks, whereas only 0% to 3% of eyes had this loss after wLASIK. Between 2% and 7% of cLASIK eyes and 11% and 31% of eyes had a significant postoperative improvement in NDS performance in every task. CONCLUSIONS: Wavefront-guided LASIK to correct myopia combined with a femtosecond laser flap significantly improved mean night driving visual performance and was significantly better than cLASIK using a mechanical keratome.

Comparison of tropicamide and cyclopentolate for cycloplegic refractions in myopic adult refractive surgery patients.

PURPOSE: To compare tropicamide 1%, a shorter-acting cycloplegic agent, with cyclopentolate 1% for cycloplegic refractions in adult refractive surgery patients. SETTING: Navy Refractive Surgery Center, Ophthalmology, Naval Medical Center, San Diego, California. METHODS: The study was prospective, single center, with randomized sequencing of cycloplegic agent; each patient received both agents. Thirty consecutive myopic adult refractive surgery patients (mean age 35.4 years) participated. A complete preoperative examination, including cycloplegic refraction, was obtained twice, 1 week apart. The patient and the examiner were masked to the medication. Main outcome measures included cycloplegic and manifest refractions, best corrected distance acuity, near-point accommodation, pupil diameters, and subjective appraisal of experience with cycloplegic agents. RESULTS: Twenty-eight of 30 patients completed both examinations. Both eyes were measured, but comparisons were limited to right and left eyes, independently. No statistically significant difference was found between the tropicamide and cyclopentolate cycloplegic refractions (mean difference in MSE +/- SD, OD=0.054 +/- 0.214 diopters (D), t=1.33, P=.10; OS=0.054 +/- 0.253 D, t=1.12, P=.14). Five eyes of 3 patients had a difference of 0.50 D or greater between the 2 agents; less myopia with cyclopentolate. Near-point testing revealed less residual accommodation with cyclopentolate (difference in MSE, OD=-0.27 +/- 0.51 D, t=2.68, P=.006; OS=-0.32 +/- 0.49 D, t=3.46, P=.001). Subjectively, 24 of 28 (86%) patients preferred tropicamide, 1 (4%) preferred cyclopentolate, and 3 (10%) had no preference. CONCLUSIONS: There was no statistically significant difference in mean cycloplegic refractions. Cyclopentolate was more effective than tropicamide in reducing accommodative amplitude in adult myopes (near-point testing). Patients strongly preferred tropicamide.

Pupil size and quality of vision after LASIK.

PURPOSE: To evaluate factors related to the quality of vision after LASIK. DESIGN: Survey study. PARTICIPANTS: One hundred consecutive patients. INTERVENTION: LASIK with a 6.0-mm elliptical ablation pattern without transition zone to treat mild to moderate myopia or astigmatism (preoperative manifest spherical equivalent [MSE], -4.79 +/- 1.33 diopters [D]; range, -2.88 to -9.25 D). The second eye was treated 1 month after the first. MAIN OUTCOME MEASURES: Completed questionnaires assessing night vision problems (glare, haze, and halo symptoms) before surgery and at 1, 3, and 6 months after surgery in 97, 75, 81, and 66 subjects, respectively. Mesopic pupil size and preoperative and postoperative variables were analyzed with questionnaire data using an analysis of variance (ANOVA) and multivariate regression analysis. RESULTS: Patients with large mesopic pupils had significantly more reports of glare, haze, and halo than did those with smaller pupils in the treated eye at 1 month after surgery (P=0.02, P=0.03, and P=0.02, respectively ANOVA) and of glare at 3 months (P=0.05). Significant predictors of symptoms at 6 months, identified through multivariate regression analysis, included preoperative MSE (for glare and haze), preoperative contrast acuity (glare), postoperative uncorrected visual acuity (UCVA; haze), and residual cylinder (haze). Together, these factors accounted for only 19% of the overall variability in glare and 37% of the variability in haze responses. No relationship between pupils and symptoms was noted at 6 months after surgery in either the ANOVA or regression analysis group. CONCLUSIONS: Patients with large pupils had more quality of vision symptoms in the early postoperative period, but no correlation was observed 6 months after surgery. Factors related to long-term symptoms include the level of treatment (preoperative myopia), preoperative contrast acuity, postoperative UCVA, and residual cylinder. Most of the variability in visual quality could not be explained by preoperative or clinical outcome measures, including pupil size.

Contrast sensitivity: establishing normative data for use in screening prospective naval pilots.

BACKGROUND: Contrast sensitivity testing can be a useful supplement to standard visual acuity tests. Currently there are no standards for contrast sensitivity in military aviation. Student naval pilots, who often have better-than-average visual acuity, could be expected to have better-than-average contrast sensitivity. Any attempt to establish contrast sensitivity standards for military aviation should begin with establishing normative data, particularly data gathered from the military aviation community. HYPOTHESIS: Student naval pilots differ from the general military population on Small Letter Contrast Test measurements. METHODS: Contrast sensitivity was measured in a group of student naval pilots (n = 107) and compared with results from aviation and non-aviation personnel. The Small Letter Contrast Test (SLCT) was used (19). Other subjects consisted of student naval flight officers (n = 40), experienced naval pilots and flight officers (n = 35 and 86, respectively), enlisted aircrew (n = 175), and other military personnel tested before undergoing photorefractive keratectomy (n = 185). RESULTS: Data collected provide large-group demographic characteristics and normative values for contrast sensitivity measured with the SLCT. Of the non-aviation controls, 95% scored at least 0.62 (read at least 7 lines plus 2 of 10 letters on the 8th line of the chart), and 95% of the student pilots scored at least 0.81, (read at least 9 lines plus 1 letter on the 10th line). CONCLUSION: Student naval pilots scored significantly better on the SLCT than the military control population. The SLCT shows potential as a screening device during induction physical examinations of military pilots.