Wavefront-guided enhancements using the wavelight excimer laser in symptomatic eyes previously treated with LASIK

PURPOSE: To describe our clinical experience in wavefront-guided LASIK enhancements using the WaveLight ALLEGRETTO system (WaveLight Technologie AG, Erlangen, Germany) for symptomatic eyes previously treated with standard LASIK. METHODS: Twenty-six eyes of 20 patients with residual myopia, hyperopia, or mixed astigmatism and/or night vision symptoms after primary standard LASIK were considered for wavefront-guided customized retreatment using the WaveLight ALLEGRETTO WAVE 200 Hz excimer laser system (model 106). Preoperative best spectacle-corrected visual acuity (BSCVA), uncorrected visual acuity, topography with the ALLEGRETTO Topolyzer, wavefront analysis using the ALLEGRETTO WAVE Tscherning Analyzer, and contrast sensitivity were compared to postoperative (enhancement) measurements. RESULTS: Twenty-two of the original 26 eyes underwent wavefront-guided enhancement, 4 were excluded because they did not meet wavefront-guided treatment inclusion guidelines of this study. Mean follow-up was 8 months (range: 6 to 13 months, standard deviation [SD] 2). All patients were within +/- 0.50 diopters (manifest refraction) of intended postoperative refraction. The mean preoperative BSCVA improved from 20/25 (SD +/- 0.12) to 20/18 (SD +/- 0.1) postoperatively. All patients gained at least one line of BSCVA, and a maximum of three lines. There was no loss of BSCVA in any patient. The total amount of high order aberrations (RMSH) decreased from an average of 1.04 (SD +/- 0.22) to 0.46 (SD +/- 0.14) microm. Patients also had a mean improvement in low contrast sensitivity of 59%. CONCLUSIONS: Based on this small series, customized wavefront-guided enhancements using the WaveLight ALLEGRETTO system in patients who underwent previous LASIK appear to be safe and effective in correcting residual refractive error, reducing high order aberrations, and improving visual symptoms when reliable and reproducible measurements are achieved.     

Topography-guided ablation for treatment of patients with irregular astigmatism

PURPOSE: To evaluate the customized aspheric treatment zone (CATz) topography-guided ablation for the correction of irregular astigmatism induced by initial corneal refractive surgery or corneal injury. METHODS: CATz ablation was performed on 32 eyes of 28 patients. Each procedure was performed by photorefractive keratectomy (PRK) or LASIK using a NIDEK EC-5000 excimer laser. The eyes had decentered ablations, small optical zones, decreased best spectacle-corrected visual acuity (BSCVA), and asymmetrical astigmatism. Subjective symptoms, uncorrected visual acuity (UCVA), BSCVA, refraction, corneal topography, and higher order aberrations were measured. Mean follow-up was 161.9 +/- 129.9 days (range: 90 to 492 days). RESULTS: Data obtained at final postoperative follow-up show that UCVA and BSCVA increased by > or = 2 lines after CATz ablation in 17 and 11 eyes and decreased in 4 and 2 eyes, respectively. Higher order aberrations were decreased in 16 eyes and increased in 1 eye. Topographical maps were improved with decreased surface regularity index (20 eyes) and surface asymmetry index (22 eyes). Seven eyes required further enhancement for residual refractive errors. Thirteen patients (15 eyes) claimed they were satisfied with the outcome, 6 patients (7 eyes) stated that the outcome was lower than expected, and 4 patients (4 eyes) stated they were dissatisfied. CONCLUSIONS: CATz topographic ablation effectively improves the quality of vision and symptoms in the majority of patients with irregular corneal astigmatism from previous excimer laser refractive surgery. However, residual or induced refractive errors may need to be corrected with a second operation after CATz.     

Target Z-axis optimized LASIK for 2 cases with decentered ablation

Purpose: To report target z-axis optimized LASIK treating for two eyes from two pa-tients with decentered ablation.Methods: The LaserSight AstraPro2.2 Z software is a topography-guided custom ellip-soid ablation platform. LASIK with target z-axis optimization was performed to restore pre-operative visual axis using a LaserSight SLX excimer laser (version 5.3,300 Hz).Results: During preoperative examination, the uncorrected visual acuity (UCVA) was 0.5 in both eyes, and the best spectacle-corrected visual acuity(BSCVA) was 1.0 and 0.8. The decentered ablation zones were diagnosed with LaserSight AstraMax topogra phy. Following target z-axis microtranslation, fifteen and eight μm of central corneal tissues were preserved in the two eyes respectively,the UCVA was 1.2 in both eyes,and secondary ablation zones were both centered on the visual axis.Topography maps and UCVA were stable in both eyes at the time of final follow-up.Conclusions: Using target z-axis optimized LASIK with the LaserSight AstraPro Plan-ner 2.2 Z customized ablation software was an effective method to modify decentered ablation and restore the visual axis.     

Wavefront-optimized versus wavefront-guided LASIK for myopic astigmatism with the ALLEGRETTO WAVE: three-month results of a prospective FDA trial

PURPOSE: To compare visual outcomes using the WaveLight ALLEGRETTO WAVE to administer either wavefront-optimized (standard LASIK) or wavefront-guided (custom LASIK) treatments in myopic eyes. METHODS: In this prospective, open-label, multicenter study conducted in the United States, 374 eyes were randomized by alternating enrollment to receive either wavefront-optimized or wavefront-guided LASIK treatments with this laser platform. Bilateral treatments were administered, with both eyes of each patient receiving the same treatment. Corneal flaps were created using the IntraLase femtosecond laser. RESULTS: In this FDA clinical trial, results at 3 months postoperatively revealed that 93% of eyes in both cohorts receiving either wavefront-optimized or wavefront-guided treatments attained an uncorrected visual acuity (UCVA) of 20/20 or better. Seventy-six percent of eyes with the wavefront-optimized treatment and 64% of eyes with the wavefront-guided treatment achieved UCVA of 20/16 or better. None of the eyes that received either treatment lost two lines or more of best spectacle-corrected visual acuity (BSCVA). In addition, 58% of eyes with wavefront-optimized treatment and 62% of eyes with wavefront-guided treatment gained one line or more of BSCVA. None of the eyes in either treatment group underwent retreatment. CONCLUSIONS: In the majority of eyes, no statistically significant differences were found between either treatment group in regard to visual acuity and refractive outcomes. Wavefront-guided treatments are not required in most cases with this laser, but may be considered if the magnitude of preoperative root-mean-square (RMS) higher order aberrations is >0.35 microm. In this study population, 83% of eyes had preoperative RMS higher order aberrations of <0.3 microm.     

Topography-guided treatment of decentered laser ablation using LaserSight's excimer laser

PURPOSE: To assess the efficacy of topography-guided laser ablation for correction of previously decentered laser ablation using LaserSight's excimer laser. METHODS: Re-treatment was performed to correct decentered ablation using LaserSight's excimer laser for 18 patients who previously underwent LASIK surgery for myopia correction in both eyes. For each patient, only the decentered eye was re-treated while the other asymptomatic eye forms a control group for this study. Measurements were conducted on ablation center, best spectacle-corrected visual acuity (BSCVA), contrast sensitivity and corneal aberrations pre- and post-operatively. RESULTS: For the retreated 18 eyes, the mean decentration was significantly reduced from 1.32+/-0.28mm to 0.61+/-0.23mm post-operatively (t=16.24, p<0.001), and with a significant improvement in mean BSCVA from 0.08+/-0.09 logMAR to 0.01+/-0.11 logMAR (t=4.58, p<0.001). The post-operative contrast sensitivity at the spatial frequencies (SF) of 1.00 and 0.70 was significantly improved (p<0.05 for both SFs). Corneal higher-order aberrations (HOAs), including the coma-like aberrations and spherical aberration, were decreased. In comparing the measurements for the retreated group to those for the control group, no significant differencewas found either in decentration or in BSCVA, but the contrast sensitivity at 0.70 was lower and the level of corneal aberrations was higher. CONCLUSIONS: Topography-guided ablation with LaserSight excimer laser is effective to correct decentered ablation. However, the re-treated eye is still inferior to the eye with originally centered ablation in corneal optical quality or visual performance.     

LASIK for hyperopia with the WaveLight excimer laser

PURPOSE: To evaluate the safety and efficacy of the ALLEGRETTO WAVE excimer laser system (WaveLight Laser Technologie AG, Erlangen, Germany) in LASIK for hyperopia and hyperopic astigmatism. METHODS: One hundred twenty consecutive LASIK cases for hyperopia with or without astigmatism treated with the ALLEGRETTO WAVE excimer laser were prospectively evaluated up to 12 months postoperatively. Patients were allocated into three groups according to their refractive sphere and cylinder: a low hyperopia group, with up to +3.00 diopters (D) sphere and astigmatism < or = +1.00 D (n = 52); a moderate hyperopia group with +3.25 to +5.00 D sphere and astigmatism of < or = +1.00 D (n = 45); and a high hyperopia/toric group with sphere > or = +5.25 D or cylinder > or = +1.25.D (n = 23). Flaps were created with the Moria M2 microkeratome (Moria, Antony, France). Parameters evaluated were pre- and postoperative refractive error, uncorrected visual acuity, best spectacle-corrected visual acuity (BSCVA), higher order aberration change, and contrast sensitivity. RESULTS: One hundred twelve eyes (93%) were available for follow-up at 12 months. Of the eyes in the low hyperopia group, 92% were within +/- 0.50 D of the refractive goal. For the moderate sphere group and the high hyperopia/toric group, 79% and 71% of eyes, respectively, were within +/- 0.50 D of the refractive goal. No eye lost > or = 2 lines of BSCVA. An increase in higher order aberrations was noted in the high hyperopia/toric group from 0.47 microm (+/- 0.096) to 0.94 microm (+/- 0.167) (P < .001). No significant changes in higher order aberrations were noted in the low and moderate hyperopia groups. CONCLUSIONS: Hyperopic LASIK using the WaveLight ALLEGRETTO WAVE excimer laser appears to be safe and effective in the correction of low, moderate, and high hyperopia and hyperopic astigmatism.     

Custom phototherapeutic keratectomy with intraoperative topography

PURPOSE: Treatment of highly aberrated eyes with opacities or irregularities consequent to previous refractive treatment, ulcers, keratitis, trauma, or corneal dystrophies remains a challenge for refractive surgeons. We evaluated the results of custom phototherapeutic keratectomy (CPK) with intraoperative corneal topography-based aberrometry and custom ablation in highly aberrated eyes. METHODS: We prospectively evaluated eyes undergoing custom phototherapeutic keratectomy (CPK) with custom ablation for corneal opacities and/or irregularities due to previous refractive treatment, keratitis, trauma, or dystrophies. Customization was planned according to corneal topography-based aberrometry, performed intraoperatively after removal of corneal epithelium. RESULTS: We treated 35 eyes of 34 patients. Mean preoperative haze was 1.6 +/- 1.4 in eyes with previous refractive surgery. Mean preoperative pachymetry was 425.7 +/- 119.3 microm. Mean preoperative spherical equivalent refraction was -1.60 +/- 3.65 D ranging from -9.38 to +10.00 D. No eye reached 20/15 best spectacle-corrected visual acuity (BSCVA), and only 63% could see 20/30 BSCVA. At final 6-month examination, mean spherical equivalent refraction was -0.71 +/- 4.01 D, ranging from -11.25 to +5.25 D. All eyes reached 20/30 or better BSCVA, and 19% had 20/15 or better BSCVA. CONCLUSIONS: Intraoperative, epithelium-free topography-based corneal aberrometry proved to be a feasible option for custom ablation in highly aberrated eyes. This approach widens the applications of PTK, providing a new procedure, custom PTK, that can be a successful solution for eyes that would otherwise require penetrating keratoplasty.     

Topography-guided custom retreatments in 27 symptomatic eyes

PURPOSE: To evaluate the use of topography-guided ablations for refractive irregularities induced by previous surgery. METHODS: This prospective, non-comparative trial comprised 27 symptomatic eyes with a history of LASIK for myopia that underwent topography-guided treatment with the ALLEGRETTO WAVE system. Pre- and postoperative refraction, uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), corneal asphericity (Q value), low contrast sensitivity, and patient's subjective assessment of improvement were measured. RESULTS: Preoperative data were sphere -0.84 +/- 1.37 diopters (D), cylinder -1.55 +/- 0.78 D, UCVA 20/49 +/- 0.22, BSCVA 20/32 +/- 0.15, and Q value 1.46 +/- 0.79. Postoperative data at mean 6-month follow-up were: sphere -0.61 +/- 0.81 D, cylinder -0.53 +/- 0.58 D, UCVA 20/25 +/- 0.21 (P < .01), BSCVA 20/21 +/- 0.14 (P < .001), and Q value 1.07 +/- 0.89. Contrast sensitivity scores improved by 70%. No loss of BSCVA occurred in any patient. CONCLUSIONS: Topography-guided treatments may be effective in correcting the quality of vision. It should be viewed as a possible two-step procedure due to spherical adjustment that may change refraction unpredictably.     

Long-term outcomes of photorefractive keratectomy in eyes with previous epikeratophakia for keratoconus

PURPOSE: To determine the long-term safety and effectiveness of photorefractive keratectomy (PRK) in the treatment of refractive errors after epikeratophakia (EP) for keratoconus. METHODS: Ten patients (14 eyes) who had refractive errors after EP for keratoconus received PRK surgery. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refractive error, corneal astigmatism, pachymetry, corneal topography, and complications were monitored. RESULTS: Mean follow-up after PRK was 63.4 +/- 19.8 months. Mean spherical equivalent was -5.5 +/- 3.9 D before PRK, -0.9 +/- 0.5 D at 1 month after PRK, and -1.5 +/- 1.0 D at 3 years. Mean astigmatism was 4.2 +/- 2.1 D before PRK, 1.2 +/- 0.5 D at 1 month after PRK, and 1.5 +/- 0.6 D at 3 years. Thirteen (93%) eyes had an UCVA <20/40, and 12 (86%) had a BSCVA of 20/40 or better before PRK. At 1 year, the UCVA was 20/40 or better in 8 (57%) eyes, and the BSCVA was 20/40 or better in all eyes. Mean central corneal thickness was 749 +/- 35 microm before PRK and 621 +/- 56 mum at 3 years. During the follow-up period, haze (grade no more than 1.0) was observed in 2 eyes. No immune rejection episode or recurrent keratoconus was found. CONCLUSIONS: PRK appears to be reliable and safe for the correction of residual ametropia after EP for keratoconus, and the visual acuity can remain stable after PRK for a long time.     

Topography-guided custom ablation for irregular corneal astigmatism using the NIDEK NAVEX Laser System

PURPOSE: To determine whether topography-guided custom ablation produces acceptable outcomes in the treatment of irregular corneal astigmatism caused by previous corneal surgery or corneal disease. METHODS: Thirteen eyes of nine patients who had irregular corneal astigmatism from previous corneal surgery or corneal disease were treated with customized aspheric treatment zone (CATz) ablations using the NIDEK Advanced Vision Excimer Laser System (NAVEX). Changes in corneal surface regularity index, surface asymmetry index, asymmetry component, corneal and ocular higher order aberrations, uncorrected visual acuity, and best spectacle-corrected visual acuity (BSCVA) were analyzed using Wilcoxon and paired t tests. A P value < .05 was considered statistically significant. RESULTS: After CATz treatment, 62% of eyes (8 of 13) showed an increase in BSCVA. Improvements in both the surface asymmetry index and asymmetry components were statistically significant after CATz treatment (P < .05). CONCLUSIONS: Topography-guided custom ablation can be safe and effective in the management of irregular corneal astigmatism due to previous corneal surgery or corneal disease.     

Two-step LASIK with topography-guided ablation to correct astigmatism after penetrating keratoplasty

PURPOSE: To assess the efficacy, predictability, stability, and safety of a two-step LASIK procedure using topography-guided ablation to correct astigmatism after penetrating keratoplasty. METHODS: Fifteen eyes of 15 patients underwent a two-step LASIK procedure at the Maggiore Hospital of Bologna, Italy. In the first step, a flap was created using the Hansatome microkeratome. In the second step, topography-guided ablation using the LaserSight LSX was planned with interactive software (CIPTA) once topographical and refractive stabilization had been obtained. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), cylindrical correction, gain of lines of BSCVA, spherical equivalent refraction, and complications were analyzed. RESULTS: Minimum follow-up was 12 months (range: 12 to 30 months). Uncorrected visual acuity improved in all 15 (100%) eyes. At the last postoperative examination, 11 (73%) eyes had UCVA > or = 20/40. Nine (60%) eyes were within 1.0 diopter (D) of the attempted correction. Mean postoperative astigmatism was -1.67 (range: -3.5 to 0; standard deviation: 1.26). Index of success of astigmatic correction was 0.26. No patient lost Snellen lines of BSCVA. Intraoperative complications included two buttonhole flaps, and postoperative complications included one flap retraction. No further laser treatment was needed. CONCLUSIONS: The two-step LASIK procedure using topography-guided ablation reduces spherical and cylindrical refractive error due to penetrating keratoplasty. Topography-guided ablation also proved to be effective in correcting irregular astigmatism.     

Photorefractive keratectomy with mitomycin C versus LASIK in custom surgeries for myopia: a bilateral prospective randomized clinical trial

PURPOSE: To compare photorefractive keratectomy (PRK) with prophylactic use of mitomycin C (MMC) and LASIK in custom surgeries for myopic astigmatism. METHODS: Eighty-eight eyes of 44 patients with a minimum estimated ablation depth of 50 microm were randomized to receive PRK with MMC 0.002% for 1 minute in one eye and LASIK in the fellow eye. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), cycloplegic refraction, slit-lamp microscopy, contrast sensitivity, specular microscopy, aberrometry, and a subjective questionnaire were evaluated. Forty-two patients completed 6-month follow-up. RESULTS: Mean spherical equivalent refraction error before surgery and mean ablation depth were -3.99+/-1.20 diopters (D) and 73.09+/-14.55 microm in LASIK eyes, and -3.85+/-1.12 D and 70.7+/-14.07 microm in PRK with MMC eyes, respectively. Uncorrected visual acuity was significantly better in PRK with MMC eyes 3 months (P=.04) and 6 months (P=.01) after surgery. Best spectacle-corrected visual acuity and spherical equivalent refraction did not differ significantly in the groups during follow-up (P>.05). Significant haze was not observed in any PRK with MMC eye. Mean higher order aberration was lower in PRK with MMC eyes postoperatively compared with LASIK eyes (P=.01). Better contrast sensitivity was observed in PRK with MMC eyes than LASIK eyes (P<.05). The endothelial cell count did not differ significantly between groups (P=.65). In terms of visual satisfaction, PRK with MMC eyes were better rated. CONCLUSIONS: Photorefractive keratectomy with MMC appears to be more effective than LASIK in custom surgery for moderate myopia. During 6-month follow-up, no toxic effects of MMC were evident. Long-term follow-up is necessary to attest its safety.     

Topographically guided excimer laser photorefractive keratectomy to treat superficial corneal opacities

OBJECTIVE: To demonstrate the efficacy and safety of topographically guided excimer laser photorefractive keratectomy (PRK) in treating superficial corneal opacities. DESIGN: Prospective, noncomparative interventional case series. METHODS: Twenty-six eyes of 24 patients with postinfectious (n = 6), post-traumatic (n = 18), and post-PRK (n = 2) scars were treated with an excimer laser linked to a computerized videokeratography unit with a topographically supported customized ablation workstation. MAIN OUTCOME MEASURES: Manifest spectacle refraction, best spectacle-corrected visual acuity (BSCVA), uncorrected visual acuity (UCVA), change of corneal clarity, and topographic indexes of surface regularity. RESULTS: The mean follow-up period was 7.7+/-2.1 months (+/- standard deviation) (range = 6-12). Corneal clarity and corneal topography patterns improved in all eyes. Uncorrected visual acuity improved from 0.7+/-0.8 logarithm of the minimum angle of resolution (logMAR) to 0.4+/-0.5 logMAR (P = 0.008), and BSCVA improved from 0.3+/-0.6 logMAR to 0.1+/-0.6 logMAR (P<0.001). The BSCVA increased in all eyes (>/=2 lines in 76.9% of eyes and 1 line in 23.1%). The mean spherical equivalent refraction changed from -0.125+/-2.77 diopters (D) to +1.33+/-1.28 D (P = 0.019). CONCLUSIONS: The use of topographically guided PRK with the topographically supported customized ablation method resulted in significant increases of UCVA and BSCVA and improved corneal clarity in all patients. The technique seems to be safe and effective for treating various superficial corneal diseases, including postinfectious, post-traumatic, and post-PRK scars.     

Combination of photorefractive and phototherapeutic keratectomy in the treatment of keratoconus

Twenty patients (28 eyes) with primary keratoconus of stages I-II (Amsler) were operated using photorefraction keratectomy (PRK) supplemented by phototherapeutic keratectomy (PRK). Mean UCVA before surgery was 0.04 +/- 0.004, BCVA 0.68 +/- 0.03. Eximer laser EC-5000(NIDEK) was used in the treatment. PRK included spherical, cylindrical ablations, or both. The diameter of ablation zone in PRK was 6 mm. in PTK the diameter of ablation zone was 8 mm, transition zone 9 mm. In PTK the ablation zone was decentered towards the cone apex (according to corneal computer topography). The method is patented in the Russian Federation. Visual acuity without correction notably improved in all 20 patients and its mean value after the operation was 0.73 +/- 0.03, 68% eye having visual acuity of 1.0. In one female patient keratoconus progressed 6 months after the operation. Haze was observed in 1 patient as a result of delayed reepithelialization. No progress of keratoconus was observed in other patients (period of observation 17.3 +/- 1.5 months). Hence, the new PRK-PTK method is an effective method for treating primary keratoconus of the first-second stage according to Amsler; the method arrests the progress of the condition in 96% cases.     

Custom-contoured ablation pattern method for the treatment of decentered laser ablations

PURPOSE: To evaluate the custom-contoured ablation pattern (C-CAP) method as a tool for providing customized laser ablations for decentered ablations based on corneal topography data. SETTING: Department of Ophthalmology, Stanford University, Stanford, California, USA. METHODS: In a prospective noncomparative interventional case series, 8 eyes from 7 post-laser in situ keratomileusis (LASIK) patients and 1 post-photorefractive keratectomy (PRK) patient with symptomatic laser decentration were treated with the C-CAP method. The Zeiss Humphrey topography system was used to identify and analyze decentered ablations. The computer software allowed the surgeon to preoperatively model the effect of various ablation schemes on the preoperative topography until a scheme that alleviated the decentration was identified. The planned ablation parameters, which included size, depth, and location of the ablation, were programmed into the Visx S4 excimer laser before treatment. RESULTS: The mean follow-up after C-CAP ablation was 4.2 months (range 1.8 to 6.3 months). At the last postoperative examination, no eye lost a line of best spectacle-corrected visual acuity (BSCVA). The uncorrected visual acuity (UCVA) improved by 3 lines in 1 eye (12.5%), by 2 lines in 1 eye (12.5%), and by 1 line in 3 eyes (37.5%); it remained unchanged in 2 eyes (25.0%) and decreased by 1 line in 1 eye (12.5%). The BSCVA improved by 3 lines in 1 eye (12.5%), by 2 lines in 2 eyes (25.0%), and by 1 line in 3 eyes (37.5%); it remained unchanged in 2 eyes (25.0%). In all eyes, including those without improvement in UCVA or BSCVA, a significant improvement in centration and subjective complaints was achieved. The pre-C-CAP and post-C-CAP root-mean-square (RMS) wavefront data were available in 5 of 8 eyes. The total and higher-order RMS aberrations decreased by 41.7% (P =.0027) and 45.5% (P =.039), respectively, after C-CAP treatment. CONCLUSIONS: Early U.S. results show the topography-driven C-CAP method is an effective tool to address untreatable postsurgical decentration. This method is presented as a technique to enhance the overall quality of vision, reduce patient-perceived visual aberrations, regularize the corneal surface, and maximize BSCVA.     

Development of unilateral corneal ectasia after PRK with ipsilateral preoperative forme fruste keratoconus

PURPOSE: To describe clinical and topographic features of keratectasia after photorefractive keratectomy (PRK) in a patient with abnormal preoperative topography. METHODS: A 25-year-old man underwent uneventful bilateral PRK for moderate myopia of -5.75 -1.75 x 95 in the right eye and -7.50 -1.25 x 80 in the left eye with best spectacle-corrected visual acuity (BSCVA) of 20/25 in both eyes. Preoperative corneal thickness was 500 microm in the right eye and 460 microm in the left eye. The total calculated ablation depth was 70 microm in the right eye and 100 microm in the left eye. Preoperative corneal topography revealed forme fruste keratoconus in the right eye with an inferior-superior ratio of 4. RESULTS: Five years postoperatively, the patient developed unilateral inferior keratectasia in the right eye with refraction of +0.50 -5.50 x 90, BSCVA of 20/100, and central corneal thickness of 481 microm with inferior corneal thickness of 374 microm. CONCLUSIONS: This case report adds to the growing body of evidence in the ophthalmic literature suggesting that patients with preoperative forme fruste keratoconus or early keratoconus may develop clinically significant progression of corneal ectasia after PRK.     

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.     

Photorefractive keratectomy retreatment after LASIK

PURPOSE: To study the results of late photorefractive keratectomy (PRK) in corneas originally subjected to LASIK. METHODS: Seven eyes of seven patients who had LASIK for myopia were retreated with PRK at least 2 years after LASIK. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refraction, and haze were evaluated before and after LASIK and after retreatment by PRK. RESULTS: Photorefractive keratectomy retreatment improved BSCVA in six (86%) of seven eyes, and one (14%) eye showed no changes. None of the eyes lost lines of BSCVA. Five of seven eyes developed mild haze, which disappeared before the last postoperative follow-up. CONCLUSIONS: Photorefractive keratectomy retreatment performed at least 2 years after LASIK can improve visual acuity. We hypothesize that LASIK-induced corneal nerve damage disturbs corneal wound healing by increasing the tendency for development of haze.     

Photorefractive keratectomy with mitomycin C after deep anterior lamellar keratoplasty for keratoconus

PURPOSE: To evaluate the safety and efficacy of photorefractive keratectomy (PRK) with intraoperative mitomycin C (MMC) after deep anterior lamellar keratoplasty (DALK) for keratoconus. METHODS: This was a prospective, noncomparative single-surgeon study. Eyes with compound myopic astigmatism after DALK with a spherical equivalent (SE) between -3 and -10 D were treated by PRK. After ablation, MMC 0.2 mg/mL was placed on the stromal bed for 45 seconds. A 6% undercorrection was planned. RESULTS: The study was completed on 10 eyes of 10 patients. The preoperative mean SE was -4.98 +/- 1.75 (SD) D. At 10 months after surgery, the mean SE was 0.28 +/- 0.61 D, and the mean defocus equivalent was 1.08 +/- 0.58 D. Postoperatively, 9 eyes were within 2 D, 6 were within 1 D, and 1 eye was within 0.5 D of defocus equivalent. The preoperative mean best spectacle-corrected visual acuity (BSCVA) was 0.68 +/- 0.15 D, and at 10 months it was 0.78 +/- 0.13 D. The 95% confidence interval for the mean difference of pre- and postoperative BSCVA was 0.02-0.17 (P < 0.05). No lines of BSCVA were lost. The mean postoperative uncorrected visual acuity was 0.55 +/- 0.1. The safety index was 1.15, and the efficacy index was 0.81. Corneal haze was grade 0 in 8 eyes and grade 0.5 in 2 eyes. Mean epithelialization time was 4.1 +/- 0.99 days. Preoperative mean endothelial cell density was 2320 +/- 184 cells/mm(2), and at 10 months it was 2284 +/- 175 cells/mm(2). CONCLUSIONS: PRK with MMC can safely and effectively correct myopia and regular myopic astigmatism after DALK. Undercorrection should be planned to compensate for the overcorrecting effect of MMC.     

Changes in corneal topography after excimer laser photorefractive keratectomy for myopia

Computer-assisted analysis of corneal topography was performed in 17 normally sighted human eyes during the first year after excimer laser photorefractive keratectomy (PRK) for myopia. Laser ablation of the central cornea produced an optical zone with a smooth power transition to the peripheral cornea. Decentration of the ablation was noted in some eyes (less than 0.5 mm in 3 eyes, 0.5 to 1.0 mm in 10 eyes, 1 to 1.5 mm in 3 eyes, and 2.1 mm in 1 eye), suggesting that careful alignment of the laser beam is critical. Improved methods to align the ablation within the center of the entrance pupil are needed. In 12 of 17 eyes, the topographic pattern appeared to stabilize between 3 and 7 months after PRK. In the remaining five eyes, central ablation power changed by more than 0.5 diopters (D) between the 6- and 12-month examinations. Regression was more common and more pronounced in eyes with intended corrections more than 5 D, whereas the majority of eyes with intended corrections of 5 D or less showed good correspondence between the final change in central ablation power and the attempted correction. Two eyes had a loss of at least two lines of best spectacle-corrected visual acuity that was attributable to irregular astigmatism, decentration of the ablation, and/or corneal opacification.