John A van Westenbrugge

Incidence and management of intraoperative and early postoperative complications in 1000 consecutive laser in situ keratomileusis cases.

OBJECTIVE To identify intraoperative and early postoperative complications of laser in situ keratomileusis (LASIK) surgery learning curve and to offer recommendations on prevention and management. DESIGN Retrospective noncomparative case series. PARTICIPANTS The first 1000 consecutive myopic LASIK eyes (April 1995-February 1997) operated on by one surgeon (HVG) were examined. INTERVENTION Myopic LASIK surgery was performed with the Chiron Corneal Shaper and NIDEK EC-5000 excimer laser. MAIN OUTCOME MEASURES The preoperative and 6-month postoperative spherical equivalent, best-corrected visual acuity, and corneal status were recorded, as was the incidence of intraoperative and early postoperative complications. The rate of retreatments was also recorded. RESULTS There were 32 (3.2%) intraoperative complications and surgical events recorded, including 19 (1.9%) microkeratome-related flap complications and 13 (1.3%) nonmicrokeratome-related surgical events such as inability to obtain sufficient suction. There were 18 (1.8%) postoperative complications requiring repositioning of microwrinkled or shifted flaps. Six-month spherical equivalent was -0.52 diopter [D] +/- 1.19 D for eyes with microkeratome complications, -0.56 D +/- 1.07 D for the group with nonmicrokeratome-related intraoperative events, and -0.78 D +/- 0.92 for eyes requiring postoperative flap repositioning. None of the 32 eyes with intraoperative complications and surgical events lost 2 or more lines of vision. One eye in the postoperative complications group lost two lines of vision. The rate of microkeratome complications related to surgical technique and the overall surgery times decreased over the course of the first 1000 myopic LASIK cases. CONCLUSION The complications encountered during the early learning curve of LASIK surgery have not in this series resulted in a significant loss of best-corrected visual acuity. With increasing surgical experience, the incidence of complications, along with surgical times, has decreased.

Simultaneous bilateral laser in situ keratomileusis: Safety and efficacy1

OBJECTIVE To compare the safety and efficacy of simultaneous bilateral to sequential bilateral laser in situ keratomileusis (LASIK) surgery for the correction of myopia. DESIGN Retrospective, nonrandomized, comparative trial. PARTICIPANTS A total of 2142 consecutive simultaneous and sequential bilateral myopic LASIK surgery eyes operated from March 1996 through June 1998 for the correction of myopia were reviewed. INTERVENTION Two surgeons (HVG and JAV) performed myopic LASIK using the Nidek EC-5000 excimer laser and either the Chiron Automated Corneal Shaper or the Bausch & Lomb Hansatome microkeratome. MAIN OUTCOME MEASURES The incidence of intra- or perioperative complications for sequential and simultaneous bilateral LASIK for myopia was recorded. Refractive and visual outcomes at 3 to 6 months postoperative were analyzed. Deviations from targeted spherical equivalent (SE), uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), and retreatment rates are reported. RESULTS Laser in situ keratomileusis was performed on the first eye of 1853 patients scheduled for simultaneous bilateral myopic LASIK. Of these, 28 (1.5%) first eyes had intraoperative or perioperative complications. The second eye surgery was cancelled in 11 cases, and 1842 second eyes completed simultaneous surgery; 13 (0.7%) intraoperative or perioperative complications occurred. Of these 41 complications in simultaneous cases, 1 eye lost 1 line of BCVA at 6 months follow-up. Two hundred eighty-nine patients were scheduled for sequential bilateral myopic LASIK. Five (1.8%) first eyes of the sequential cases had intraoperative complications compared with four (1.4%) sequential second eyes. There was no loss of BCVA in any sequential bilateral case with complications at a minimum at 6 months follow-up. There was no statistically significant difference between intra- and perioperative complication rates comparing simultaneous to sequential bilateral LASIK. Three to 6 months postoperative visual and refractive data were reviewed; except when comparing simultaneous first eye postoperative SE to sequential first eye, there was no statistically significant difference in refractive or visual outcomes, including deviation from targeted SE, UCVA, BCVA, and retreatment rates. CONCLUSION Simultaneous bilateral LASIK is as safe and effective as sequential surgery. Simultaneous bilateral LASIK may offer several benefits to the patient.

Accuracy and predictability of intraocular lens power calculation after photorefractive keratectomy.

PURPOSE To investigate the accuracy and predictability of intraocular lens (IOL) power calculation in postoperative photorefractive keratectomy (PRK) eyes. SETTING Gimbel Eye Centre, Calgary, Alberta, Canada. METHODS The results in 5 cataract surgery eyes that had had PRK were analyzed retrospectively. Target refractions based on actual and refraction-derived keratometric values were compared with postoperative achieved refractions. The target refractions calculated using 5 IOL formulas and 2 A-constants were also compared with the achieved refractions. RESULTS In postoperative PRK eyes, the power calculation was more accurate and predictable when the smaller of either the actual or refraction-derived keratometric value was used to calculate the IOL power. The difference between target and achieved refractions appeared smaller when the Binkhorst formula was used. No significant hyperopic shift was observed after cataract surgery. CONCLUSION The smaller of the actual or the refraction-derived keratometric value is recommended for calculating IOL power in post-PRK eyes.

Comparison of laser and manual removal of corneal epithelium for photorefractive keratectomy.

BACKGROUND Photorefractive keratectomy relies on precise ablation of cornea stromal tissue to achieve a desired change in refraction. The routine technique for photorefractive keratectomy has been manual debridement of the epithelium prior to performing excimer laser ablation. We investigated whether laser ablation versus manual debridement of the corneal epithelium influences the refractive result. METHODS A retrospective matched controlled study analyzing the refractive outcome of 46 eyes after excimer laser photorefractive keratectomy was performed. Half of the eyes had the corneal epithelium ablated with the excimer laser, while the other half had mechanical removal. Topical postoperative corticosteroid dosing was different in the two groups. All photorefractive keratectomies were performed by the same surgeon (H.V.G.). The two groups were analyzed for statistical differences in refractive outcomes and corneal haze after 6 months. RESULTS The mean preoperative spherical equivalent refraction in the laser removal group was -5.11 diopters (D), and -5.09 D in the manual group. At 6 months postoperatively, the mean spherical equivalent refraction in the laser group was +0.03 D and -0.40 D for the manual group (p = .21). At no point postoperatively was there any significant difference in the mean refractive outcome or variance of the refractive results between the two groups, although there was a trend toward greater correction with laser ablation of epithelium. There was no statistical difference in the amount of stromal haze by slit-lamp microscopy in the two different debridement groups. There was no significant difference in final uncorrected visual acuity, rate of reepithelialization, or reported incidence of halos or glare between the two groups. CONCLUSION There was a tendency toward greater refractive correction at 6 months using the laser for corneal epithelial removal than manual debridement, although the difference was not statistically significant. The trend toward slightly higher correction emphasizes the need for care when removing epithelium with the laser to prevent concomitant stromal ablation.

Visual, Refractive, and Patient Satisfaction Results Following Bilateral Photorefractive Keratectomy for Myopia

Reports of the visual, refractive, and patient satisfaction results after photorefractive keratectomy (PRK) are now becoming available. The visual, refractive, and patient satisfaction results of 52 patients after bilateral excimer laser photorefractive keratectomy for myopia were studied. Patient satisfaction was measured using a five-part questionnaire. Initial patients obtained an overcorrection which necessitated adjusting the programmed correction to 75% of targeted correction.

Incidence of retinal detachment following Nd:YAG capsulotomy after cataract surgery

ABSTRACT In a retrospective study, we reviewed 218 consecutive Nd:YAG laser posterior capsulotomies performed at the Gimbel Eye Centre between June 1987 and November 1989 for the incidence of retinal detachment (RD) following treatment. Matched controls were found for 198 YAG cases. The median post‐surgical follow‐up for the YAG cases was 49.5 months; for the controls, 50.0 months. The median time between cataract extraction and YAG laser posterior capsulotomy was 24.8 months. The median follow‐up after YAG was 24.2 months. Two of the 198 YAG cases (1.0%) and one of the 198 controls (0.5%) had RD. In the YAG cases, RD occurred 54.8 and 36.5 months after cataract surgery; in the control cases, 51.8 months after cataract surgery. Retinal detachment occurred at 15.0 and 17.0 months after YAG capsulotomy. These rates were lower than those reported in the literature. We feel that the surgical techniques of continuous circular capsulorhexis and in‐the‐bag IOL placement reduce the risk of RD following Nd:YAG posterior capsulotomy.

Wavefront-guided Multipoint (Segmental) Custom Ablation Enhancement Using the Nidek NAVEX Platform

PURPOSE To present our clinical experience regarding enhancement (retreatment) of previously performed non-wavefront-guided refractive surgery by wavefront-guided multipoint (segmental) custom ablation utilizing the Nidek NAVEX platform. METHODS Retrospective clinical analysis was conducted of 20 eyes (19 patients) with mixed myopic or hyperopic astigmatism who had undergone primary laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) and reported postoperative reductions in quality of vision. These vision disturbances correlated with clinically significant elevations in the root mean square of higher order aberrations (RMS of HOA) values. Before wavefront-guided multipoint (segmental) custom ablation enhancement with the NAVEX platform, all patients underwent testing with the Nidek Optical Path Difference Scan (OPD-Scan) and analysis with Final Fit Software. RESULTS Twenty eyes showed improvement or resolution of visual symptoms following wavefront-guided multipoint (segmental) custom ablation enhancement. The postoperative root mean square of higher order aberration values were variable and not always related to improvement in visual function. No patient lost two or more lines of best spectacle-corrected visual acuity. CONCLUSION Topography and wavefrontguided multipoint (segmental) custom ablation enhancements were safe and effective in improving visual symptoms following primary refractive surgery. In some eyes, improved visual function without correspondingly lower RMS of HOA values may be an effect of neutralizing some chromatic aberrations across the visible light spectrum, thereby improving the modulation transfer function.

Assessment of nerve fiber layer thickness before and after laser in situ keratomileusis using scanning laser polarimetry with variable corneal compensation.

Purpose: To determine the effect of laser in situ keratomileusis (LASIK) on retinal nerve fiber layer (RNFL) thickness measurements obtained by scanning laser polarimetry with variable corneal compensation (SLP‐VCC). Setting: Gimbel Eye Centre, Calgary, Alberta. Methods: Retinal nerve fiber layer thickness measurements were performed in both eyes of 25 consecutive healthy patients the day of LASIK surgery and 1 month after by trained examiners using the GDx‐VCC nerve fiber analyzer. Thickness measurements and all other parameters provided by the software of the machine before and after LASIK were analyzed using the paired Student t test. Results: Mean age of the patients was 39 years ± 9.6 (SD) (range 24 to 57 years). The mean preoperative spherical equivalent was −4.15 ± 1.76 diopters (D) (range −1.0 to −7.50 D) and the mean postoperative spherical equivalent, 0.12 ± 0.39 D (range −0.75 to +1.00 D). Mean ablation depth was 62 ± 23 μm. No statistically significant difference was found in SLP parameters after LASIK (P<.05). No clinically significant difference in RNFL thickness measurements was noted in any eye. Conclusion: These data suggest that SLP‐VCC mean thickness measurements are not influenced by LASIK‐induced alterations in corneal architecture. Measurements obtained with SLP‐VCC before surgery may be used for future comparisons.

Necrotizing Keratitis after Laser Refractive Surgery in Patients with Inactive Inflammatory Bowel Disease

Two cases of necrotizing keratitis following laser refractive corneal surgery, with stable and controlled Crohn’s disease are described. A 40-year-old woman developed bilateral stromal inflammation and inferior thinning in the right eye along the flap edge within 1 day of uneventful bilateral IntraLase laser-assisted in situ keratomileusis. The other case is a 30-year-old man who also developed bilateral inferior stromal infiltrates 2 days following photorefractive keratectomy. Both cases were aggressively treated with systemic and topical corticosteroids. The infiltrates in both patients gradually resolved, with one relapse during the 7 months period of follow-up in the first case. These cases highlight the importance of taking precautions considering this and similar autoimmune conditions as a relative contraindication to refractive surgery.

Intraocular availability and pupillary effect of flurbiprofen and indomethacin during cataract surgery

Purpose: To compare the bioavailability and pupillary effect of flurbiprofen and indomethacin during phacoemulsification and intraocular lens implantation. Setting: Gimbel Eye Centre, Calgary, Alberta, Canada. Methods: In this prospective, randomized, double‐masked study, 236 patients had cataract extraction by phacoemulsification and posterior chamber intraocular lens implantation. They received topical flurbiprofen 0.03% solution or indomethacin 1 % suspension applied every 15 minutes for 60 to 75 minutes before surgery. An aqueous humor sample (100 &mgr;L) was taken immediately before the corneal incision was made. Pupil diameters (horizontal and vertical) were measured before aqueous humor sampling, after phacoemulsification, after irrigation and aspiration (I/A), and after acetylcholine instillation. Results: Mean concentration of flurbiprofen and indomethacin in the aqueous humor was 59.8 ng/mL and 90.2 ng/mL, respectively (P < .001). The percentage of dose detected in the aqueous humor was 4.38% in the flurbiprofen group and 0.21 % in the indomethacin group (P < .001). Pupil diameters were 7.2 and 7.3 mm presurgery and 7.0 and 7.0 mm after I/A in the flurbiprofen and indomethacin groups, respectively (P > .05). No adverse events were reported in either group. Conclusions: Although the absolute concentration of indomethacin was higher, the percentage of dose detected in the aqueous humor was 20 times greater in the flurbiprofen than in the indomethacin group. Flurbiprofen is absorbed 20 times more readily than indomethacin. Both drugs were equally effective in preventing miosis during cataract surgery.