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.

Simultaneous bilateral laser in situ keratomileusis: safety and efficacy.

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.

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.

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.

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.

Effect of sulcus vs capsular fixation on YAG-induced pressure rises following posterior capsulotomy.

Neodymium-YAG capsulotomy for secondary cataracts can induce acute intraocular pressure rises, possibly by a blocking of the trabecular meshwork by debris. To test a hypothesis that bag-fixated intraocular lenses may act as a barrier to debris, thus reducing pressure rises after YAG capsulotomy, we conducted a study comparing pressures (at 1, 2, 3, 6, and 24 hours after YAG capsulotomy) between bag-fixated and sulcus-fixated cases. There were substantial and statistically significant intraocular pressure rises in the sulcus-fixated group starting at 1 and 2 hours after YAG capsulotomy, and peaking at 3 hours (mean rise, 7.83 mm Hg). There were no such peaks of intraocular pressure rise among bag-fixated cases (mean change, -0.32 mm Hg at 3 hours). There was a weak but significant (r = -.18) correlation between the change 1 hour after YAG capsulotomy in intraocular pressure and percent of enclosure of the intraocular lens optic among bag-fixated cases. Higher proportions (fourfold to fivefold) of cases with sulcus-fixated lenses had significant flare and particulate matter in the anterior chamber, compared with bag-fixated cases.

Treatment of iris melanoma by photocoagulation: a case report.

A 13-year-old white male was found to have a melanoma of the iris. Three treatments with xenon arc photocoagulation resulted in regression of the lesion with development of an iris coloboma. There were no complications, and corrected visual acuity has remained at 20/15 after a 19-year follow-up.