Effect of varying the optical zone diameter on the results of hyperopic laser in situ keratomileusis.

PURPOSE: To compare the predictability and safety of laser in situ keratomileusis (LASIK) for low to moderate spherical hyperopia using different ablation zone diameters. DESIGN: Retrospective, nonrandomized, comparative trial. PARTICIPANTS: Forty-nine eyes that underwent hyperopic LASIK. INTERVENTION: Two surgeons (JMD, RKM) performed hyperopic LASIK using the VISX STAR S2 excimer laser (VISX, Inc., Sunnyvale, CA) and the Bausch & Lomb Hansatome microkeratome (Chiron Vision, Irvine, CA) using ablation zone diameters of 5 x 9 mm, 5.5 x 8.5 mm, or 6 x 9 mm (the first number represents the optical zone diameter and the second number represents the diameter of the outer border of the ablation zone). MAIN OUTCOME MEASURES: Refractive and visual outcomes at 3 to 6 months after surgery were analyzed. Groups were compared for deviations from targeted spherical equivalent, uncorrected visual acuity, and loss of best spectacle-corrected visual acuity (BSCVA). RESULTS: The mean intended hyperopic correction was +2.48 +/- 1.13 diopters (D; 0.63-5.50 D). There were 16 eyes in the 5 x 9-mm group, 15 eyes in the 5.5 x 8.5-mm group, and 18 eyes in the 6 x 9-mm group. On average, the 5 x 9-mm group achieved 97% of the programmed correction, the 5.5 x 8.5-mm group achieved 104%, and the 6 x 9-mm group achieved 112% of the programmed correction. The tendency toward overcorrection in the 6 x 9-mm group compared with the 5 x 9-mm group was statistically significant (P < 0.05). The incidence of one line loss of BSCVA was greatest in the 5 x 9-mm group (19%) and lowest in the 6 x 9-mm group (6%). These differences were not statistically significant. No eyes experienced a loss of two or more lines of BSCVA at last examination. CONCLUSIONS: Hyperopic LASIK using the VISX STAR is safe and effective using different ablation zone diameters. There appears to be an increased tendency toward overcorrection with progressively larger optical zone diameters.

Intraocular lens power calculations in patients with extreme myopia.

PURPOSE: To determine the variables that might contribute to improved intraocular lens (IOL) power calculations preoperatively in cataract patients with extreme myopia. METHODS: This retrospective study included 50 patients with extreme myopia and axial lengths longer than 27.0 mm. All patients had clear corneal phacoemulsification by the same surgeon and implantation of the Domilens SiFlex 1 IOL (power range -6.0 to +5.0 diopters [D]). The performances of the SRK/T, Hoffer Q, Holladay 1, and Holladay 2 formulas in predicting an IOL power that would meet the target refraction of +/-1.00 D were compared. RESULTS: The formulas tended to suggest underpowered IOLs, more severe in eyes with axial lengths greater than 30.00 mm. These eyes accounted for most of the minus-power IOLs implanted. Back calculations of axial lengths in patients with minus-power IOLs showed that, on average, emmetropia could have been predicted by choosing shorter axial lengths (up to 2.72 mm shorter) than those used in the original IOL power calculations. Preoperative B-scan ultrasonography demonstrated the presence of a posterior pole staphyloma temporal to the optic nerve in several patients who required minus-power IOLs, which suggests that axial length measurement problems were a major source of IOL calculation errors in these patients. CONCLUSIONS: In eyes with axial lengths longer than or equal to 27.0 mm, current third- and fourth-generation lens calculation formulas have a tendency to over minus patients between -1.0 and -4.0 D. The formulas appear to perform better for plus-power IOL implantation than for minus-power IOL implantation. The use of B-scan ultrasonography to locate posterior pole staphylomas may improve the accuracy of IOL calculations in eyes with extreme myopia.

Combined posterior chamber phakic intraocular lens and laser in situ keratomileusis: bioptics for extreme myopia.

PURPOSE: To examine the efficacy, predictability, stability, and safety of combined posterior chamber phakic intraocular lens (IOL) implantation and laser in situ keratomileusis (LASIK) in eyes with extreme myopia. METHODS: We analyzed the results of 67 eyes that received a posterior chamber hydrogel-collagen plate phakic IOL (STAAR Collamer Implantable Contact Lens) and also underwent secondary LASIK for the correction of extreme myopia. Mean follow-up was 3 months after the LASIK portion of the procedure (range, 1 day to 6 mo after LASIK). RESULTS: Mean preoperative spherical equivalent refraction was -23.00 +/- 3.60 D (range, -18.75 to -35.00 D), and mean refractive cylinder was 1.50 +/- 1.20 D (range, 0 to 5.00 D). Mean spherical equivalent refraction after IOL implantation and before LASIK was -6.00 +/- 2.80 D (range, -2.00 to -14.38 D) and mean refractive cylinder 1.50 +/- 1.10 D (range, 0 to 5.00 D). Mean postoperative spherical equivalent refraction at last examination after the LASIK portion of the two-part phakic IOL-LASIK procedure was -0.20 +/- 0.90 D (range, +1.75 to -5.13 D), and mean refractive cylinder was 0.50 +/- 0.50 (range, 0 to 2.25 D). Eighty-five percent (57 eyes) were within +/- 1.00 D and 67% (45 eyes) were within +/- 0.50 D of emmetropia at last examination. The refractions remained stable with a statistically insignificant change (P > .05 at each interval) during follow-up. Postoperative uncorrected visual acuity at last examination was 20/20 or better in 3% (2 eyes) and 20/40 or better in 69% (46 eyes). A gain of 2 or more lines of spectacle-corrected visual acuity was seen in 51 eyes (76%) and no eyes lost 2 or more lines of spectacle-corrected visual acuity at last examination. CONCLUSION: Combined posterior chamber phakic IOL implantation with the STAAR Collamer plate lens and LASIK (bioptics) is an effective and reasonably predictable method for correcting myopia from -18 to -35 D. Gains in spectacle-corrected visual acuity were common, and results demonstrated good short-term safety and refractive stability.

Posterior chamber phakic intraocular lens for myopia of -8 to -19 diopters.

PURPOSE: To examine the efficacy, predictability, stability, and safety of posterior chamber phakic intraocular lens (IOL) implantation in patients with extreme myopia. METHODS: We analyzed the results of 124 eyes that received a posterior chamber hydrogel collagen plate phakic IOL (Staar Collamer Implantable Contact Lens, ICL) for the correction of their myopia. The target postoperative spherical equivalent refraction was emmetropia. Mean follow-up was 11 months (range 1 to 36 mo). RESULTS: The mean preoperative spherical equivalent refraction was -13.38 +/- 2.23 D (range, -8.50 to -18.63 D). Mean postoperative spherical equivalent refraction at last examination was -0.78 +/- 0.87 D (range, +1.63 to -3.50 D), with 69% (86 eyes) within +/-1.00 D and 44% (55 eyes) within +/-0.50 D of emmetropia. The refraction remained stable with a statistically insignificant change (p > 0.05 at each interval) during follow-up. A gain of two or more lines of spectacle-corrected visual acuity was seen in 36% (45 eyes) at last examination. One eye (0.8%) lost two or more lines of spectacle-corrected visual acuity from a retinal detachment. CONCLUSION: Posterior chamber phakic IOL implantation with the Staar Collamer plate lens is an effective and safe method for reducing or correcting myopia between -8 and -19 D. Gains in spectacle-corrected visual acuity were common, and results suggested good refractive stability. Improvements in phakic IOL power calculation formulas are needed to improve the predictability of refractive outcome.

Posterior chamber phakic intraocular lens for hyperopia of +4 to +11 diopters.

PURPOSE: To examine the efficacy, predictability, stability, and safety of posterior chamber phakic intraocular lens (IOL) implantation in eyes with high hyperopia. METHODS: We analyzed the results of 24 eyes that received a posterior chamber hydrogel-collagen plate phakic IOL (Staar Collamer Implantable Contact Lens, ICL) for the correction of hyperopia with the goal of emmetropia. Mean follow-up was 8.4 months (range, 1 to 18 mo). RESULTS: The mean preoperative spherical equivalent refraction was +6.51 +/- 2.08 D (range, +3.75 to +10.50 D). Mean postoperative spherical equivalent refraction at last examination was -0.39 +/- 1.29 D (range, +1.25 to -3.88 D), with 79% (19 eyes) within +/-1.00 D and 58% (14 eyes) within +/-0.50 D of emmetropia. Postoperative uncorrected visual acuity at last examination was 20/20 or better in 8% (two eyes) and 20/40 or better in 63% (15 eyes). A gain of two or more lines of spectacle-corrected visual acuity was seen in two eyes (8%) at last examination. One eye (4%) lost two or more lines of spectacle-corrected visual acuity due to progressive neovascular glaucoma initiated by early postoperative pupillary block. CONCLUSION: Posterior chamber phakic IOL implantation with the Staar Collamer plate lens is an effective method for correcting high hyperopia. Large, patent iridotomies are important in hyperopic eyes to lower the risk of postoperative pupillary block. Improved phakic IOL power calculation formulas will refine predictability of refractive outcome.

Results and complications of laser in situ keratomileusis by experienced surgeons.

PURPOSE: To identify intraoperative and early postoperative adverse events and complications that may be encountered after the laser in-situ keratomileusis (LASIK) learning process. METHODS: One hundred sixty-nine consecutive eyes of 108 patients who had LASIK by a surgeon experienced in LASIK were studied. All intraoperative and early postoperative adverse events and complications were noted. Patients were examined at 1 day and 1 to 3 months after surgery. Six baseline refractive groups were studied: high myopia with astigmatism (-10.25 to -17.50 D; 18 eyes), moderate myopia with astigmatism (-6.00 to -9.50 D; 31 eyes), low myopia with astigmatism (-0.75 to -5.87 D; 81 eyes), mixed astigmatism (-0.25 to +0.50 D; 6 eyes), low to moderate hyperopia with astigmatism (+1.00 to +3.75 D; 19 eyes), and high hyperopia with astigmatism (+4.25 to +7.37 D; 12 eyes). Seventy-eight percent (132 eyes) had a primary LASIK procedure; 22% (37 eyes) had LASIK after previous refractive surgery. Primary and secondary LASIK procedures were analyzed together. The Nidek EC-5000 or the Chiron PlanoScan excimer lasers were used. RESULTS: The most commonly observed adverse intraoperative events were minor corneal bleeding (3%) and thin flap (1%). The most commonly observed postoperative events were punctate epithelial keratopathy (6%) and small epithelial defect 1 day after surgery (5%). The most serious complication occurred in three eyes with preoperative high hyperopia (spherical equivalent refraction greater than +4.00 D) in which corneal topographic abnormalities resulted. At last examination, mean postoperative spherical equivalent refraction was less than +1.00 D in all groups. Spectacle-corrected visual acuity was 20/20 in 70 eyes (41%) and 20/25 or better in 119 eyes (70%). Loss of spectacle-corrected visual acuity of two or more lines occurred in five eyes (3%), three of which had preoperative high hyperopia with abnormal postoperative corneal topography. CONCLUSION: Our prospective study should help LASIK surgeons gauge their expectations of intraoperative and early postoperative complications. Surgeons should proceed cautiously when treating patients with high hyperopia, because a higher incidence of loss of spectacle-corrected visual acuity may be encountered postoperatively.

Laser in situ keratomileusis for myopia from -5.50 to -11.50 diopters with astigmatism.

PURPOSE: To determine the efficacy, predictability, safety, and short-term stability of laser in situ keratomileusis (LASIK) in treating patients with high myopia and astigmatism. METHODS: We retrospectively studied the results of our initial 119 eyes with myopia ranging from -5.50 to -11.50 D and astigmatism less than 4.00 D that underwent LASIK with the Nidek EC-5000 excimer laser. Follow-up was at 1 day, 1 month, and 3 to 6 months; follow-up was 71% (84 eyes) at the 3 to 6 month visit (average 4.5 months). RESULTS: Of the 84 eyes with 3 to 6 months of follow-up, mean baseline spherical equivalent refraction was -8.62 +/- 1.27 D and mean cylinder was -1.84 +/- 1.02 D. Mean postoperative spherical equivalent refraction at the last examination was -0.61 +/- 0.84 D and mean cylinder was -0.39 +/- 0.38 D, with 83% (70 eyes) achieving a spherical equivalent refraction within +/-1.00 D of emmetropia, and 56% (47 eyes) within +/-0.50 D. Mean regression of spherical equivalent from 1 day to 1 month was less than -0.50 D and refractions were stable between 1 month and 3 to 6 months. An uncorrected visual acuity of 20/40 or better was noted in 84% (71 eyes) of these eyes on day 1 after surgery, in 75% (63 eyes) at 1 month, and in 77% (65 eyes) at 3 to 6 months. Twenty-two percent (18 eyes) of these eyes achieved 20/20 or better uncorrected visual acuity at 3 to 6 months; only 17% (14 eyes) had 20/20 or better spectacle-corrected visual acuity before surgery. One patient lost two or more lines of spectacle-corrected visual acuity at the last examination due to epidemic keratoconjunctivitis. CONCLUSION: LASIK with the Nidek EC-5000 excimer laser appears to be an effective and safe means for treating patients with high myopia and astigmatism. Studies with longer follow-up will help evaluate the long-term stability of the procedure and the possibility of late complications.