Proper positioning of the plume evacuator in the VISX Star3 excimer laser minimizes central island formation in patients undergoing laser in situ keratomileusis

PURPOSE: To identify risk factors in a series of patients who developed steep central islands after laser in situ keratomileusis (LASIK). METHODS: We analyzed and compared the refractive and topographic outcome of a study group composed of 83 eyes of 44 patients who underwent LASIK using the VISX Star3 excimer laser with a refraction-matched control group of 83 eyes treated later. The vacuum aspirator of the excimer laser was abnormally positioned during the surgeries performed in the study group. RESULTS: Mean preoperative spherical equivalent refraction in the study group was -6.75 +/- 2.50 D. Four eyes with a mean preoperative spherical equivalent refraction of -9.27 +/- 2.29 D developed steep central islands. Thirty-three (38%) of 83 eyes treated needed retreatment for residual myopia or myopic astigmatism. In the control group, mean preoperative spherical equivalent refraction was -6.76 +/- 2.50 D. Ninety-three percent of eyes were within +/- 1.00 D of target refraction. Five (6.02%) of 83 eyes required retreatment and no eyes developed central islands. CONCLUSION: The abnormally positioned vacuum aspirator coupled with the higher preoperative refractive correction were the likely causative factors for central island formation and the increased incidence of undercorrection in these patients.     

Topographic centration of ablation after LASIK for myopia using the CustomVue VISX S4 excimer laser

PURPOSE: To determine the ablation centration, efficacy, predictability, and safety of CustomVue LASIK using the VISX S4 excimer laser for the treatment of myopia and myopic astigmatism. METHODS: A retrospective review of 20 myopic eyes of 12 patients treated with LASIK CustomVue VISX S4 was conducted. Corneal topography was used to determine ablation centration. Primary outcome variables including manifest refraction, best spectacle-corrected visual acuity (BSCVA), uncorrected visual acuity (UCVA), and complications were evaluated at 3 months postoperatively. RESULTS: Mean decentration (from ablation zone to entrance pupil) was 0.23 +/- 0.08 mm at 3 months postoperatively. No eyes were decentered > 0.5 mm. Preoperatively, the mean spherical equivalent refraction was -4.81 +/- 11.39 diopters (D) (range: -6.75 to -2.25 D). At 3 months postoperatively, mean spherical equivalent refraction was -0.63 +/- 0.25 D (range: -2.00 to 0.25 D). Nineteen (95%) of 20 eyes had UCVA of 20/40 and 16 (80%) of 20 eyes had UCVA of 20/20 at 3 months postoperatively. Fourteen (70%) eyes were within +/- 0.50 D and 18 (90%) eyes were within +/- 1.00 D of emmetropia. No eye lost > 1 line of BSCVA. CONCLUSIONS: Wavefront-guided LASIK using the CustomVue VISX S4 for myopic eyes results in minimal decentration ablation and effective, predictable, and safe visual outcomes.     

Arcuate keratotomy for asymmetrical steep islands after laser in situ keratomileusis and automated lamellar keratoplasty

PURPOSE: To determine the safety and efficacy of arcuate keratotomy (AK) to reduce or eliminate steep asymmetrical islands after laser in situ keratomileusis (LASIK) and automated lamellar keratoplasty (ALK). SETTING: Rancho Bernardo Laser and Vision Center, San Diego, California, USA. METHODS: This retrospective and noncomparative interventional study comprised 8 eyes of 5 patients who received arcuate incisions to reduce topographically defined asymmetrical steep islands after LASIK (n = 7) and ALK for hyperopia (n = 1). The islands occurred unexpectedly after standard excimer laser treatment (VISX Star and S2) for myopic astigmatism that induced irregular astigmatism and unwanted optical effects. Cases occurred consecutively over 16 months, an incidence of less than 1%. Arcuate incisions extended 30 or 45 degrees in LASIK eyes based on the amount of residual refractive astigmatism and were placed at 7.0 mm on the steep axis. Radial incisions were limbal sparing to a 5.0 mm optical zone following the Casebeer nomogram. Outcome measures were uniformity of postenhancement topography, uncorrected visual acuity (UCVA), postenhancement refraction, and reduction in unwanted optical effects. RESULTS: The preenhancement mean spherical equivalent (SE) in the LASIK eyes was -0.99 diopters (D) +/- 0.48 (SD); the astigmatism ranged from 0.50 to 1.75 D. After incisional keratotomy, the mean SE was -0.21 +/- 0.12 D and the net residual astigmatism was reduced to a range of 0 to 0.75 D. All 8 eyes had AK to reduce topographically defined steep islands that were causing visual blurring and unwanted optical effects including ghosting, halos, and polyplopia. After enhancement, there was a marked reduction in the asymmetrical steep islands by topography, fewer unwanted optical effects, less refractive astigmatism, and improved UCVA. Two patients retained small inferior steep areas that may indicate forme fruste keratoconus, although this condition was not detected preoperatively by topographical indices. CONCLUSION: Uncorrected visual acuity improved and unwanted optical effects were reduced after AK on the peripheral axis of asymmetrical steep islands that occurred after uneventful LASIK and hyperopic ALK. This relatively simple incisional approach may be used until more advanced topography-linked ablations with rapid and precise eye tracking are perfected and widely available.     

Photoastigmatic refractive keratectomy for low, moderate, and high astigmatism using a broad beam excimer laser: evaluataion according to new international criteria

BACKGROUND: Photorefractive keratectomy (PRK) is an accepted procedure to correct myopia in Germany. The purpose of this study was to evaluate photoastigmatic refractive keratectomy (PARK) for myopic astigmatism. MATERIAL AND METHODS: PARK using the VISX 20/20 excimer laser was performed in 50 eyes of 36 patients (25 female, 16 male) aged 22 to 68 years (mean 38 +/- 10 years) in the period of 1995 to 1996. Retrospective evaluation was done after dividing the patients into three astigmatic groups between -0.5 diopters (D) and -1.5 D (group I, n = 28), between -1.75 D and -3.0 D (group II, n = 16) und between -3.25 D and -5.5 D (group III, n = 6). The correction of myopic astigmatism was assessed concerning the criteria safety, efficacy, predictability and stability. Mean follow-up was 12 months (8-15 months). RESULTS: Seventy-eight % of all eyes achieved an uncorrected visual acuity of > 0.5. Sixty-eight % of the eyes were within +/- 1.0 D of the desired correction. Loss of 2 or more lines of best corrected visual acuity occurred in 6 eyes (12.0%). We observed in group I an astigmatic reduction of 36.0%, in group II of 66.5% and in group III of 68.0%. The surgically induced astigmatism was calculated with 1.29 +/- 1.0 D. Mean axis rotation of the refractive cylinder was 22.12 +/- 23.05 degrees. CONCLUSIONS: PARK using the VISX 20/20 excimer laser is an acceptable procedure to correct myopic astigmatism. However, the study revealed that astigmatic reduction with a broad beam laser is not yet perfect in terms of efficacy, predictability and safety.     

Nomogram adjustment of laser in situ keratomileusis for myopia and myopic astigmatism with the Alcon LADARVision system

PURPOSE: To evaluate the visual and refractive results of conventional (non-wavefront) laser in situ keratomileusis (LASIK) for treatment of myopia and myopic astigmatism using the Alcon LADARVision 4000 excimer laser system and nomogram adjustment techniques. METHODS: A retrospective analysis of 499 eyes that had LASIK for myopia and myopic astigmatism was performed. Preoperative manifest spherical equivalent refraction ranged from -0.43 to -6.00 D and preoperative astigmatism ranged from 0 to -4.75 D. Patients were evaluated during 3 months following surgery. RESULTS: One month after surgery, 72% of eyes examined (298/415 eyes) had uncorrected visual acuity (UCVA) of 20/20 or better. Three months after surgery, 83% of eyes examined (216/261 eyes) had UCVA of 20/20 or better. One and three months after surgery, 82% and 83% of eyes, respectively, were within +/-0.50 D of attempted correction; 97% of eyes were within +/-1.00 D at both 1 and 3 months. No eye lost more than 1 line of best spectacle-corrected visual acuity (BSCVA) at 3 months after surgery. At the 3-month examination, 83% of eyes had UCVA better than or equal to preoperative BSCVA. CONCLUSIONS: Conventional LASIK to correct myopia and myopic astigmatism was safe and effective using the Alcon LADARVision 4000 excimer laser system. Outcomes were substantially improved throughout development of an accurate nomogram, derived from continually updated regression analysis of previous refractive results.     

Laser in situ keratomileusis for the correction of myopia and myopic astigmatism

PURPOSE: To evaluate the efficacy, safety, predictability, and surgically induced astigmatism (SIA) of laser in situ keratomileusis (LASIK) for the correction of myopia and myopic astigmatism. SETTING: Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan. METHODS: This retrospective study comprised 69 eyes that had LASIK to correct myopia and 74 eyes that had LASIK to correct myopic astigmatism. The excimer laser keratectomy was performed using a Summit Apex Plus machine. Refraction, visual acuity, and computerized corneal videokeratography data from the preoperative and postoperative examinations were collected. The astigmatic change was calculated by the Alpins vector analysis method. RESULTS: The preoperative spherical equivalent at the glasses plane in the myopia and myopic astigmatism groups was -8.08 diopters (D) and -9.73 D, respectively. At 6 months, the spherical equivalent and residual corneal astigmatism were -0.25 D and 0.85 D, respectively, in the myopia group and -0.71 D and 0.82 D, respectively, in the myopic astigmatism group. In the myopia group, 88% of eyes were within +/-1.0 D of the intended myopia correction and in the myopic astigmatism group, 85% were within +/-1.0 D of the targeted spherical equivalent and 90% were within +/-1.0 D of the intended astigmatism correction. The uncorrected visual acuity was 20/40 or better in 94.1% of eyes in the myopia group and 92.5% of eyes in the myopic astigmatism group. The SIA magnitude was 0.66 D with the axis randomly distributed in the myopia group. The mean astigmatism correction index was 0.97, the mean magnitude of error was 0.13 D +/- 0.62 (SD), and the mean angle of error was -3.70 +/- 13.73 degrees in the myopic astigmatism group. CONCLUSION: Laser in situ keratomileusis had similar predictability, safety, and efficacy in the treatment of myopia and myopic astigmatism. The astigmatism correction was effective, but the results suggest that subjective astigmatism of less than 1.0 D need not be treated with the Summit Apex Plus laser.     

Eight-year follow-up of photorefractive keratectomy for myopia

PURPOSE: We evaluated 8-year results of excimer laser photorefractive keratectomy (PRK) for myopia in terms of stability and late complications. METHODS: Ninety-two myopic eyes of 55 patients were treated with a single-step method using an Aesculap-Meditec MEL 60 excimer laser with a 5.0-mm ablation zone. Treated eyes were divided into three groups according to preoperative refraction: low myopes (< or = -6.00 D), medium myopes (-6.10 to -10.00 D), and high myopes (>-10.00 D). RESULTS: Change in myopic regression stabilized in all myopia groups within 12 months, although a small myopic shift occurred up to 8 years after PRK. Mean change in refraction between 2 and 8 years was -0.42 +/- 0.48 D for low myopes, -0.37 +/- 0.34 D for medium myopes, and -0.41 +/- 0.50 D for high myopes. The percentage of eyes within +/- 1.00 D of emmetropia 8 years after PRK was 78.3% in the low myopia group, 68.8% in the medium myopia group, and 57.1% in the high myopia group. One eye lost 2 lines of best spectacle-corrected visual acuity due to irregular astigmatism. In 13.0% of eyes, a residual trace corneal haze was observed, which had no effect on visual acuity. Apart from the loss of 2 lines of BSCVA in one eye, there were no other late complications during the study period. CONCLUSIONS: The mean change in refraction between 2 and 8 years was less than -0.50 D, regardless of preoperative refraction, and may be attributed to natural age-related refractive change. The appearance of residual corneal haze after 8 years correlated with the amount of myopic correction. PRK was a safe and stable surgical procedure in this group of patients.     

Photoastigmatic refractive keratectomy in myopes. Nidek US Investigators Group

PURPOSE: Photoastigmatic refractive keratectomy (PARK) was studied in a multi-center clinical trial. The Nidek EC-5000 excimer laser was evaluated for its effect on refraction, visual acuity, and safety measures as part of a U.S. Food and Drug Administration (FDA) regulated study. METHODS: Eight U.S. centers enrolled adults with eyes having refractive astigmatism up to 4.00 D and a myopic spherical equivalent refraction up to -8.00 D. Results are reported for 749 eyes of 486 patients with at least 6 months follow-up. The rectangular beam scanning Nidek EC-5000 used a 5.5-mm-diameter treatment zone, a 7.0-mm-diameter peripheral blend zone, and a 40 Hz pulse rate for surface treatment of myopic astigmatism. Nomogram corrections to machine settings were required to achieve the desired results. RESULTS: Preoperative average spherical equivalent refraction of -4.90+/-1.74 D was reduced to -0.02+/-0.79 D at 6 months. Refractive stability was established at 3 months. Over 62% of eyes were within +/-0.50 D of desired correction at 6 months, with over 86% within +/-1.00 D. Uncorrected visual acuity improved by an average of 10 Snellen lines; over 64% of eyes saw 20/20 or better uncorrected and over 93% saw 20/40 or better uncorrected at 6 and 12 months. PARK treatment effectively reduced astigmatism with little average axis error or magnitude error. Corneal haze and safety concerns were minimal. CONCLUSIONS: Photoastigmatic refractive keratectomy using the Nidek EC-5000 excimer laser provided significant reduction of myopia and astigmatism, with minimal complications.     

Diameters of topographic optical zone and programmed ablation zone for laser in situ keratomileusis for myopia

PURPOSE: To compare topographic optical zones with programmed ablation zone settings of eyes treated with laser in situ keratomileusis (LASIK) for myopia using the VISX S2 excimer laser. METHODS: Two-hundred three eyes treated with LASIK using the VISX S2 excimer laser were retrospectively evaluated to determine the size of the topographic optical zone. Three to six months after LASIK, the topographic optical zone was measured at the zone of highest curvature on topography and subtraction topography. Eyes were divided into four groups (A, B, C, D) in order of increasing myopia. RESULTS: When the topographic optical zone was compared with the programmed ablation zone, an optical zone reduction of 0.5 +/- 0.1 mm and 0.4 +/- 0.1 mm was found for the longest and shortest diameters, respectively. For eyes with spherical ablation zones, this reduction was 0.6 +/- 0.1 mm and 0.4 +/- 0.1 mm shorter than the programmed horizontal and vertical dimensions. Groups A, B, C, and D, in order of increasing myopia, all showed reductions of approximately 0.5 +/- 0.1 mm for the longest and 0.3 to 0.4 +/- 0.1 mm for the shortest diameters of the optical zone. CONCLUSIONS: The topographic optical zone was reduced from the programmed ablation zone. This reduction was statistically significant for both elliptical and spherical ablations, and seemed to be independent of the amount of myopia.     

Laser in situ keratomileusis for undercorrection after radial keratotomy.

PURPOSE: To assess the safety and efficacy of excimer laser in situ keratomileusis (LASIK) in treating residual myopia and/or astigmatism following refractive keratotomy. METHODS: Fourteen eyes that had previously undergone radial and/or arcuate keratotomy were included. The surgeries were performed using the Chiron Automated Microkeratome and the VISX 20/20B excimer laser. RESULTS: Average follow-up was 12.64+/-5.02 months. Mean spherical equivalent refraction was reduced from -3.48+/-3.52 D preoperatively to -0.04+/-0.87 D postoperatively. At the last follow-up examination there were 8 eyes (57.1%) with a refraction within+/-0.50 D, and 10 eyes (71.4%) within +/-1.00 D of emmetropia. Uncorrected visual acuity was 20/20 or better in 4 eyes (28.6%) and 20/40 or better in 10 eyes (71.4%). Vector analysis of the astigmatic correction showed an index of success of 80%. There was no significant loss (> or = or =2 lines) of spectacle-corrected visual acuity. We observed interface epithelial ingrowth in one eye. CONCLUSIONS: The correction of residual myopia and/or astigmatism with LASIK in eyes with prior refractive keratotomy proved to be safe and effective. Careful preoperative evaluation may help to avoid complications such as reopening of incisions during surgery or postoperative ingrowth of epithelium beneath the corneal flap.     

Ten-year follow-up of laser in situ keratomileusis for high myopia

PURPOSE: To evaluate the long-term outcomes of laser in situ keratomileusis (LASIK) for high myopia. DESIGN: A long-term (10 years) follow-up retrospective interventional case series study. METHODS: The study included 196 myopic eyes of 118 patients with a mean preoperative spherical equivalent of -13.95 +/- 2.79 diopter (D) treated with myopic LASIK at the Instituto Oftalmológico de Alicante, Spain using the VISX 20/20 excimer laser (VISX Inc, Santa Monica, California, USA) and the Automated Corneal Shaper microkeratome (Chiron Vision, Irvine, California, USA). All patients were evaluated three months, one year, two years, five years, and 10 years postoperatively. The main outcome measures were refractive predictability and stability, mean corneal keratometry, topographical cylinder, safety, efficacy, stability of visual acuity, and postoperative complications. RESULTS: At 10 years, 82 (42%) of 196 eyes were within +/-1.00 D and 119 (61%) were within +/-2.00 D. Fifty-four (27.5%) eyes underwent retreatments attributable to under correction and/or regression. The myopic regression decreases with time in eyes that did not undergo retreatment with a mean rate of -0.25 +/- 0.18 D per year. Eleven eyes (5%) lost more than 2 lines of best spectacle-corrected visual acuity (BSCVA) and 78 eyes (40%) showed a postoperatively uncorrected visual acuity of 20/40 or better. Two eyes (1%) with more than 15 D myopic correction developed corneal ectasia. CONCLUSIONS: LASIK for myopia over -10 D is a safe procedure with myopic regression that slows down with time and a high rate of BSCVA increase in the long-term.     

Ten-year follow-up of photorefractive keratectomy for myopia of more than -6 diopters

PURPOSE: To evaluate the long-term outcomes of excimer laser myopic photorefractive keratectomy (PRK) for myopia higher than -6 diopters (D). DESIGN: A long-term (10-year) follow-up retrospective, interventional case series. METHODS: The study included 267 eyes of 191 patients with myopia with spherical equivalent (SE) of more than -6 D treated with myopic PRK at the Instituto Oftalmológico de Alicante, Alicante, Spain, using the VISX 20/20 excimer laser (Santa Clara, California, USA). All patients were evaluated three months, one year, two years, five years, and 10 years after surgery. The main outcome measures were refractive predictability and stability, mean corneal keratometry, topographical cylinder, safety, efficacy, stability of visual acuity, and postoperative complications. RESULTS: At 10 years, 156 (58%) of 267 eyes were within +/- 1.00 D and 209 (78%) were within +/- 2.00 D. One hundred and twenty-four eyes (46.4%) underwent retreatments because of overcorrection, regression, or both. The mean SE decreased (myopic regression) in eyes that did not undergo retreatment, with a mean magnitude of -1.33 +/- 2.0 D over 10 years (-1.13 +/- 0.20 D per year). One hundred and twenty-one (48.3%) of 267 eyes demonstrated increase in best spectacle-corrected visual acuity, and only eight eyes lost lines of vision because of cataract and posterior segment-related complications. The mean corneal haze score decreased gradually from 0.48 +/- 0.69 at three months to 0.09 +/- 0.33 at 10 years. CONCLUSIONS: PRK for myopia of more than -6 D is a safe and effective procedure in the long-term.     

Laser in situ keratomileusis for myopic astigmatism with the Nidek EC-5000 laser

PURPOSE: We studied the efficacy, predictability, and safety of laser in situ keratomileusis (LASIK) for moderate to high simple and compound myopic astigmatism. METHODS: Ninety-two eyes of 46 consecutive patients who had LASIK for myopic astigmatism (64 eyes, astigmatism 3.00 to 9.00 D; myopia 0 to -20.00 D), or simple myopia (28 eyes, myopia -4.00 to -20.00 D; astigmatism 0 to 0.50 D) were retrospectively studied. Mean baseline spherical equivalent refraction (SE) in the myopia group was -8.11 +/- 3.94 D and in the astigmatism group, -8.55 +/- 4.49 D. All eyes underwent LASIK using the Nidek EC-5000 laser by the same surgeon. RESULTS: At 6 months after LASIK in the myopia group versus the astigmatism group, 24 eyes (85%) vs. 54 eyes (84%) were available for follow-up, 12 eyes (50%) vs. 13 eyes (24%) had uncorrected visual acuity (UCVA) of 20/20, 19 eyes (79%) vs. 44 eyes (81%) had UCVA of 20/40, 8 eyes (33%) vs. 18 eyes (33%) had SE within +/- 0.50 D, 15 eyes (62%) vs. 39 eyes (72%) had SE within +/- 1.00 D, and mean SE was -1.22 +/- 1.17 D vs. -0.74 +/- 1.46 D. Mean astigmatism (vertexed to the corneal plane) in the astigmatism group was 2.77 D at 0 degrees before surgery and 0.32 D at 7 degrees at 6 months. None of the myopic eyes and three of the astigmatic eyes (5%) lost > or = 2 lines of best spectacle-corrected visual acuity. CONCLUSION: LASIK with the Nidek EC-5000 laser for myopic astigmatism was reasonably effective, predictable, and safe. Astigmatism was under-corrected with the nomogram implemented in this study.     

Photorefractive keratectomy for residual myopia after cataract surgery

PURPOSE: To evaluate the effectiveness, predictability, and safety of photorefractive keratectomy (PRK) for correcting residual myopia and myopic astigmatism after cataract surgery with intraocular lens implantation. SETTING: Refractive Surgery and Cornea Unit, Instituto Oftalmológico de Alicante, Alicante, Spain. METHODS: Thirty consecutive eyes (30 patients) had PRK for residual myopia after cataract surgery. Surface PRK with a VISX Twenty-Twenty excimer laser was used in all patients. Follow-up was 1 year. RESULTS: Before PRK, no eye had an uncorrected visual acuity (UCVA) of 20/40 or better. Twelve months after PRK, 16 eyes (53.33%) had a UCVA of 20/40 or better. After PRK, best corrected visual acuity (BCVA) improved 1 line or more in 14 eyes (46.66%) over the preoperative values, and 15 eyes (50.00%) had the same BCVA as before PRK. Mean pre-PRK refraction of -5.00 diopters (D) +/- 2.50 (SD) decreased significantly to -0.25 +/- 0.50 D at 12 months (P < .001). At 12 months, the spherical equivalent was within +/- 1.00 D of emmetropia in 27 eyes (90.00%). No vision-threatening complications occurred. CONCLUSION: Photorefractive keratectomy was an effective, predictable, and safe procedure for correcting residual myopia and myopic astigmatism after cataract surgery.     

Prospective study of photorefractive keratectomy for myopia using the VISX StarS2 excimer laser system

PURPOSE: To evaluate the safety, efficacy, and predictability of excimer laser photorefractive keratectomy (PRK) for compound myopic astigmatism using the VISX StarS2 excimer laser system with international version 3.1 software. METHODS: We report a prospective consecutive study of myopic excimer laser PRK, performed in a multi-surgeon environment with 200 eyes of 117 patients, to correct naturally occurring compound myopic astigmatism of between -0.50 to -5.90 D manifest refractive sphere and up to -3.50 D manifest refractive astigmatism. Patients were assessed prior to surgery and at 1, 3, 6, and 12 months after treatment. RESULTS: One hundred and ninety-eight of 200 treatments (99%) were reviewed 1 year after surgery; 193 of 198 eyes (97%) achieved 20/40 or better uncorrected visual acuity and 163 of 198 eyes (82%) achieved 20/20 or better. One eye lost two lines of Snellen visual acuity assessed at 12 months but recovered acuity when assessed at 18 months. Mean spherical equivalent corneal plane power was reduced from -3.50 to +0.90 D 1 month after treatment and 0 D at 12 months (SD 0.67 D). Three eyes of three patients underwent further treatment, two with LASIK and one with PRK for residual refractive error. Refractive astigmatism of >1.00 D was reduced from a mean -1.70 to -0.70 D at 1 year after treatment. Vector magnitude was 79% of that intended and mean vector axis error (absolute) was 8.5 degrees. No eye had a severe haze response. Pelli-Robson contrast acuity was significantly reduced after treatment from a mean 1.72 D preoperatively to 1.63 D at 12 months (P<.01). CONCLUSIONS: PRK for myopia using the VISX StarS2 excimer laser system was effective in the treatment of low myopic astigmatism, although there was a significant reduction in Pelli-Robson contrast sensitivity.     

One year clinical results of photoastigmatic refractive keratectomy for compound myopic astigmatism.

PURPOSE: To evaluate the efficacy, predictability, and safety of excimer laser photoastigmatic refractive keratectomy (PARK) to correct compound myopic astigmatism. SETTING: Departments of Ophthalmology, Robert Debré Hospital and Rothschild Foundation, Paris, France. METHODS: This retrospective study included 27 eyes with compound myopic astigmatism treated with a Nidek EC 5000 excimer laser. The refractive results were measured at 1 year, and the cylindrical component was analyzed by the Alpins method. Mean preoperative myopia was -4.50 diopters (D) (range -0.75 to -4.00 D) and mean preoperative cylinder, -1.64 D (range -0.75 to -4.00 D). RESULTS: At 1 year, the spherical equivalent was -0.47 D (range +1.00 to -3.00 D) and residual subjective astigmatism, -0.40 (range -0.25 to -1.50 D). Uncorrected visual acuity of 20/40 or better was obtained in 22 of the 27 eyes; 21 eyes were within +/- 1.0 D of emmetropia. Vector analysis showed a mean coefficient adjustment of 1.50 D +/- 0.53 (SD), a mean axis shift of 2.64 +/- 12.10 degrees, and a mean magnitude of error of 0.45 +/- 0.56 D. Haze was absent in 22 eyes and grade 1+ in 5 eyes. Five eyes gained 1 line of best corrected visual acuity and 3 lost 1 line. No patient lost more than 1 line. CONCLUSION: Excimer laser PARK successfully corrected low and moderate myopia combined with up to 4.0 D of astigmatism with a low mean angle of error. To increase the accuracy of toric ablation, specific algorithms for the cylinder component are needed.     

Epi-LASEK for the correction of myopia and myopic astigmatism

PURPOSE: To analyze patient results after laser-assisted subepithelial keratectomy (epi-LASEK) for myopia and myopic astigmatism. SETTING: Private practice setting, Columbus, Ohio, USA. METHODS: Three hundred forty-three eyes of 188 patients with myopia or myopic astigmatism were prospectively evaluated after having epi-LASEK by a single surgeon using the VISX Star S2 excimer laser. Uncorrected visual acuity (UCVA), manifest refraction, postoperative pain, time to epithelial healing, and postoperative haze were recorded. The patients were followed for up to 6 months. RESULTS: The mean preoperative sphere and cylinder were -5.42 diopters (D) +/- 2.62 (SD) (range -1.0 to -14.0 D) and 0.87 +/- 0.75 D (range 0 to 4.75 D), respectively. At 1 week, the mean UCVA was 20/30. At 6 months, it was 20/40 or better in 98% of patients. At 3 months, 78% and 92% of patients were within +/-0.5 D and +/-1.0 D, respectively, of the intended correction. This improved to 85% and 94%, respectively, at 6 months. The mean time to epithelial healing was 4.76 days (range 3 to 9 days). Most patients (87%) reported no postoperative pain. In the first 3 months, haze was noted in 1.6% of patients. CONCLUSIONS: Epi-LASEK appeared to be a safe and effective treatment for the correction of myopia and myopic astigmatism. Most patients achieved postoperative visual acuities comparable to those with laser in situ keratomileusis and photorefractive keratectomy. There was a low incidence of haze and pain postoperatively.     

Topographic changes in corneal asphericity and effective optical zone after laser in situ keratomileusis

PURPOSE: To determine the relationship between the spherical refractive change after myopic excimer laser surgery and the effective optical zone (EOZ) and corneal asphericity determined by corneal topography. SETTING: Baylor College of Medicine, Houston, Texas, USA. METHODS: Preoperative and postoperative topographies along with refractions were evaluated in all patients who had had laser in situ keratomileusis since January 1999 and had at least 6 months of follow-up. The VISX Smoothscan S2 excimer laser and the Hansatome microkeratome (Bausch & Lomb) were used in all cases. Because optical zones are oval with astigmatic treatments with the VISX laser, only patients with spherical refractions and treatments were included. Thirty-nine cases met the criteria; their treatments ranged from -1.50 to -18.00 diopters (D). The preoperative and postoperative corneal asphericities (Q-values) were taken directly from the Holladay Diagnostic Summary Report on the EyeSys 2000, version 4.0. The mean diameter of the optical zone was measured on the local radius of curvature map using the outer edge of the yellow zone, which corresponds to 2 color changes or approximately 0.50 D steepening from the mean central radius (green). RESULTS: The EOZ decreased as the amount of treatment increased. The decrease was slightly nonlinear, decreasing slightly more rapidly at higher treatments. For an "intended" 6.0 mm optical zone, the nominal EOZs from the least-squares second-order polynomial regression were 6.0 mm for -1.5 D, 5.4 mm for -5.0 D, 4.6 mm for -10.0 D, 3.8 mm for -15.0 D, and 3.2 mm for -18.0 D. The least-squares second-order polynomial regression yielded a standard error of the estimate (SEE) of +/- 0.22 mm (R(2) = 0.90). The asphericity increased nonlinearly in a positive direction (oblate) with the amount of treatment, indicating greater amounts of correction produced progressively more oblate corneal surfaces. The least-squares second-order polynomial regression yielded an SEE of +/- 0.42 (R(2) = 0.55). CONCLUSIONS: The EOZ decreased and the Q-value increased with the amount of myopic excimer laser treatment. The optical zone was approximately 4.3 mm with a spherical treatment of -12.0 D. These findings may explain the clinical studies that indicate high myopic treatments (above -12.0 D) are associated with poor visual outcomes.     

One-year evaluation of myopic laser photoastigmatic refractive keratectomy using the summit apex plus: phase III of a Food and Drug Administration clinical trial

PURPOSE: To prospectively evaluate the safety and efficacy of the Summit Apex Plus excimer laser in the treatment of primary compound myopic astigmatism. DESIGN: Prospective noncomparative interventional case series. PARTICIPANTS: Patients with primary compound myopic astigmatism: sphere of -1.0 to -7.0 diopters (D) and cylinder -1.0 to -5.0 D. METHODS: Ninety-three eyes of 56 patients with a mean spherical equivalent of -4.98 +/- 1.80 D (-1.75 to -8.5) underwent photoastigmatic refractive keratectomy (PARK) with the Summit Apex Plus excimer laser using erodible mask technology. Prospective follow-up is analyzed at 1-year postoperatively. MAIN OUTCOME MEASURES: Postoperative reduction in myopic sphere, myopic astigmatism, spherical equivalent, angle of error, magnitude of error, difference vector, uncorrected visual acuity, and corneal haze. RESULTS: Seventy-one eyes were available at 1-year follow-up. Mean spherical equivalent was reduced 86.5% to a mean residual of -0. 65 D +/-0.70 D (-2.88-+1.13 D). Astigmatism was reduced 66.2% to a mean residual of -0.76 +/- 0.52 D (-2.25-0.00 D); 77.5% were within 1.0 D of attempted correction; 1.4% of eyes experienced an overcorrection >1.0 D of spherical equivalent; 0.27 D of mean myopic regression was demonstrated between 1 and 12 months; 93.0% of eyes achieved an uncorrected visual acuity of 20/40 or better; and 49.3% of eyes achieved an uncorrected visual acuity of 20/20 or better. CONCLUSIONS: PARK with the Summit Apex Plus excimer laser is effective at reducing compound myopic astigmatism. However, current laser algorithms result in consistent undercorrection of both the compound myopia and the astigmatic component.     

Laser in situ keratomileusis for myopic astigmatism

PURPOSE: To evaluate the refractive results of laser in situ keratomileusis (LASIK) for myopic astigmatic eyes, and to assess the efficacy, accuracy, stability, and safety of the procedure. METHODS: LASIK was performed on 113 eyes of 73 patients for correction of myopic astigmatism ranging from 1.00 to 5.00 D, as measured by manifest refraction, with a mean baseline refractive astigmatism of 2.09 +/- 1.12 D. The Chiron Automated Corneal Shaper was used to create a corneal flap, and laser ablation was performed using the Chiron-Technolas Keracor 116 excimer laser. Follow-up time was 12 months for all eyes. RESULTS: Refractive astigmatism was stable by 3 months after surgery. At 1 year after LASIK, refractive astigmatism was reduced to a mean of 0.25 +/- 0.31 D (range 0 to 1.00 D). Sixty-one eyes (54%) had no residual astigmatism and 98 eyes (86.7%) had 0 to 0.50 D of refractive astigmatism. The mean percent reduction of preoperative astigmatism was 87.9 +/- 14.9%. The mean axis deviation of the surgically induced astigmatism was 2.1 +/- 3.1 degrees, with 96 eyes (84.9%) within 5 degrees of the desired axis. The percent correction of preoperative astigmatism in the proper axis was 97.1 +/- 15.5%. Spectacle-corrected visual acuity improved by 2 lines in 11 eyes (9.7%), and was reduced by 1 line only in 1 eye. There were no other significant complications. CONCLUSION: LASIK with the Chiron-Technolas Keracor 116 excimer laser was effective for correction of myopic astigmatism, with good stability after 3 months. The results were predictable with an acceptable degree of accuracy. LASIK is a safe procedure with very few complications.