Ablation centration in laser in situ keratomileusis for hyperopia: comparison of VISX S3 ActiveTrak and VISX S2

PURPOSE: To compare ablation centration and outcome measurements in laser in situ keratomileusis (LASIK) for hyperopia using the pupil-tracking VISX S3 ActiveTrak or the nontracking VISX S2 excimer laser. METHODS: In a retrospective study, 49 consecutively treated hyperopic eyes (32 patients) that had LASIK by the VISX StarS3 ActiveTrak were compared to 49 control-matched eyes treated with the VISX StarS2 without pupil-tracking. Primary outcome variables including ablation centration, uncorrected visual acuity, best spectacle-corrected visual acuity, manifest refraction, complications, and induced cylinder analyzed by vector analysis were evaluated 3 months postoperatively. RESULTS: Hyperopic sphere ranged between plano and +5.50 D and cylinder between 0 and +2.75 D. Ninety-five of 98 eyes (96.9%) were available for analysis at 3 months. Of these 95, 52 eyes could be used for analysis of ablation centration. Mean decentration of the ablation zone from the entrance pupil was 0.30 +/- 0.20 mm in tracked eyes (n=31) and 0.41 +/- 0.39 mm in nontracked eyes (n=21), P=.17. Two eyes (6.5%) in the tracked group were significantly decentered between 0.5 and 1 mm from the pupil center. In the nontracked group, decentration was between 0.5 and 1 mm in one eye (4.8%) and greater than 1 mm in two eyes (9.5%). CONCLUSIONS: Comparable ablation centration in LASIK for hyperopia was achieved between actively-tracked and nontracked eyes. Decentrations (greater than 1 mm) were not seen with a tracking system in this study. Visual and refractive results were similar between the VISX StarS3 ActiveTrak and VISX StarS2 laser systems.     

Hyperopic LASIK following intracorneal hydrogel lens explantation

PURPOSE: To report hyperopic LASIK results after intracorneal hydrogel lens explantation in a bilateral hyperopic patient. METHODS: Slit-lamp examination showed diffuse corneal opacity around the lens edge and over the anterior lens surface affecting both eyes with uncorrected visual acuity of 0.4 in the right eye and 0.5 in the left eye. RESULTS: The intracorneal hydrogel lenses were explanted, and 6 months later hyperopic LASIK using the Schwind ESIRIS excimer laser (Schwind, Kleinostheim, Germany) was performed after lifting the same flap for the intracorneal hydrogel lens implantation. Six months after hyperopic LASIK, visual acuity recovered to the initial preoperative best spectacle-corrected levels: right eye 0.8 with +1.50 D sphere and left eye 0.9 with +1.00 -0.50 x 90 degrees. Central corneal transparency also fully recovered. CONCLUSIONS: Hyperopic LASIK is a possible alternative after intracorneal hydrogel lens explantation in hyperopic eyes.     

Laser in situ keratomileusis with a flying-spot excimer laser and a carriazo-barraquer microkeratome - outcomes after 6 months

PURPOSE: To evaluate safety, efficacy, predictability and refractive stability of LASIK, using a flying-spot excimer laser, 91 eyes were examined during a 6-months follow-up. PATIENTS AND METHODS: Consecutively, 91 eyes were enrolled in the study, each eye previously underwent LASIK with the ESIRIS excimer laser (ESIRIS, supplier: eye-tech-solutions Schwind, Kleinostheim, Germany). 91 myopic eyes (mean preoperative refraction: - 5.4 D, range: - 3 to - 13.3 D, astigmatism: - 1 D, range: 1.3 to 3.5 D) were included. A full ophthalmological examination was performed during the first week, 1, 3 and 6 months postoperatively. RESULTS: 26 % of all eyes achieved an uncorrected visual acuity of 0.8, 35 % of 1.0 and 5 % 1.2 6 months postoperatively. 23 % of the eyes lost 1 line of best spectacle-corrected visual acuity (BSCVA), 25 % gained one or more lines of BSCVA. Refraction of 90 eyes were within +/- 1 D of emmetropia 6 months postoperatively. There was no change in spherical equivalent within the interval of 6 months, all eyes were within +/- 0.5 D. CONCLUSION: LASIK with the ESIRIS excimer laser was an effective and safe option with good stability and predictability within the specified interval.     

Centration analysis of ablation over the coaxial corneal light reflex for hyperopic LASIK

PURPOSE: To analyze postoperative topographic centration when the coaxially sighted corneal light reflex was used for laser centration in hyperopic LASIK. METHODS: Centration photographs of 21 eyes (12 patients) that underwent hyperopic LASIK with centration over the coaxially sighted corneal light reflex were reviewed to determine the distance from the entrance pupil center to the coaxially sighted corneal light reflex. Postoperative ablation centration was determined topographically at day 1 and 3 months by four different methods. The difference between the actual decentration and the decentration that would have occurred had the ablation been centered over the entrance pupil center was calculated. RESULTS: The mean deviation of the coaxially sighted corneal light reflex from the entrance pupil center preoperatively was 0.34 +/- 0.24 mm nasal or 4.5 +/- 3.0 degrees. At 1 day, the average decentration was 0.10 mm or 1.3 degrees temporal. The mean decentration that would have occurred if the ablation had been centered over the entrance pupil center was 0.44 mm or 5.5 degrees temporal. At 3 months, the average decentration was 0.07 mm or 0.25 degrees temporal. The mean decentration that would have occurred if the ablation had been centered over the entrance pupil center was 0.45 mm or 5.6 degrees temporal. Mean uncorrected visual acuity (logMAR) improved 3 lines from 0.54 +/- 0.14 (20/70) to 0.22 +/- 0.17 (20/32). No eye lost >2 lines of best spectacle-corrected visual acuity (BSCVA); 2 (10%) eyes lost 1 line of BSCVA at 3-month follow-up. CONCLUSIONS: Excellent centration in hyperopic ablation is possible even in eyes with positive angle kappa when the ablation is centered over the corneal light reflex.     

Topographic changes after hyperopic LASIK with the SCHWIND ESIRIS laser platform

PURPOSE: To analyze and compare refractive power changes with topographic changes after hyperopic LASIK using the ESIRIS laser platform. METHODS: Sixty-six consecutive eyes of 37 patients were evaluated retrospectively. Outcomes were evaluated at 3 months. In all cases, standard examinations including pre- and postoperative topographic and corneal wavefront analysis with a Keratron topographer were performed. Preoperative mean spherical equivalent was +/- 2.74 diopters (D) with a mean cylinder of 0.67 D. The ESIRIS excimer laser system was used to perform ablations. Topographic changes of Maloney index, simulated keratometry (sim-K), and K-reading at 5 and 7 mm were evaluated. RESULTS: Ninety-two percent of eyes were within +/- 0.50 D manifest refraction at 3 months postoperatively. Changes in refraction, Maloney indices, and sim-K indices after surgery were strongly correlated with the intended correction. Induction of negative corneal spherical aberrations and increased prolate asphericity was correlated with the achieved defocus correction. No other Zernike mode was significantly correlated. Topographically, an overcorrection within the central 3 mm and a gradual peripheral undercorrection also was observed. CONCLUSIONS: Analyzing the topographic maps, the corneal power change of the Maloney indices correlated with the intended correction. After hyperopic LASIK, an overcorrection was observed in the 3-mm central zone, and progressive undercorrections were observed in the 5- and 7-mm zones.     

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.     

Corneal aberration changes after hyperopic LASIK: a comparison between the VISX Star S2 and the Asclepion-Meditec MEL 70 G Scan excimer lasers

PURPOSE: To compute and compare anterior corneal aberration changes following hyperopic LASIK using two different excimer lasers: the VISX Star S2 and the Asclepion-Meditec MEL 70 G Scan. METHODS: The right eyes of 43 patients with preoperative refraction ranging from +0.75 to +5.50 diopters (D) and astigmatism ranging from 0.00 to 1.00 D were randomly divided into two groups. The first group was operated with the Star S2, a broad-beam excimer laser (n = 22), and the second group with the MEL 70, a flying-spot excimer laser (n = 21). Total higher order aberrations (Z(i), n > or = 3), coma (Z (+/- 1(3)), Z (+/- 1(5)), and spherical aberration (Z0(4)) values were computed from videokeratography using CT View software preoperatively and 6 months postoperatively, for 3.0- and 6.5-mm aperture diameters. RESULTS: Higher order aberrations, coma, and spherical aberration increased after hyperopic LASIK and were greater for larger pupil diameters in both groups. No statistically significant differences were found between the Star S2 and MEL 70 excimer lasers in terms of aberrometric increase, mean postoperative visual acuity, and residual refraction. CONCLUSIONS: Anterior corneal aberrations increase after hyperopic LASIK. The type of laser (Star S2 versus MEL 70) seems to have no impact on the amount of anterior corneal aberrations induced after hyperopic LASIK.     

Measurement of the spatial shift of the pupil center

PURPOSE: To evaluate the effectiveness of the pupil center as an anatomic landmark for excimer laser treatments. SETTING: Sekal-Microchirurgia-Rovigo Centre, Rovigo, Italy. METHODS: Pupillometry with the Costruzione Strumenti Oftalmici S.R.L. (CSO) pupil-measuring module (incorporated in Eye Top videokeratoscope) was performed in 52 patients with a diagnosis of myopia and in 25 patients with a diagnosis of hyperopia. Measurements both in mesopic and photopic conditions consisted of pupil diameters, spatial shift of the pupil center, and the distance between the pupil center and keratoscopic axis. RESULTS: The mean pupil diameter in photopic conditions of illumination in myopic eyes was 3.52 mm +/- 0.56 (SD), while in mesopic conditions it was 5.37 +/- 0.78 mm; in hyperopic eyes the mean photopic pupil diameter was 3.01 +/- 0.46 mm, while the mean mesopic diameter was 5.12 +/- 0.48 mm. The mean spatial shift of the pupil center in myopic eyes was 0.086 mm (maximum 0.269 mm), while in the hyperopic eyes it was 0.095 mm (maximum 0.283 mm). The mean distance between the pupil center and keratoscopic axis in myopic eyes was 0.226 +/- 0.13 mm (maximum 0.75 mm), while in hyperopic eyes it was 0.45 +/- 0.19 mm (maximum 0.8 mm). CONCLUSIONS: The mean of the measured pupil sizes was greater in myopic eyes than in hyperopic eyes. The spatial shift of the pupil center, as the pupil dilates, was relatively small in all groups; therefore, the pupil center is a good anatomic landmark for both traditional refractive surgery and wavefront-guided treatments. The mean distance between the keratoscopic axis and pupil center was greater in the hyperopic group than in the myopic group. Therefore, centration of any laser treatment on the basis of the keratoscopic analysis should be done carefully, especially in hyperopic eyes and in cases in which the pupil center is meaningfully shifted from keratoscopic axis, even in photopic conditions of illumination.     

Eye movement during laser in situ keratomileusis

PURPOSE: To measure eye motion in patients having laser in situ keratomileusis (LASIK) using a video technique and determine centration and variance of the eye position during surgery. SETTING: Laser refractive surgery center. METHODS: The procedure was videotaped in 5 consecutive eyes having LASIK performed by a single surgeon with the VISX Star S2 excimer laser. Following surgery, video images of the eyes were digitized and stored in a computer for processing. Digitized images were obtained at a rate of 25 images per second during the laser procedure. The pupil margin and a visual landmark, such as a scleral blood vessel, were identified in the initial image of each eye. Custom software was used to track the location of the landmark and the pupil center in subsequent images. RESULTS: Three of the 5 eyes were well centered on average. The remaining 2 eyes were decentered inferiorly by approximately 0.25 mm. The standard deviation in all eyes was approximately 0.10 mm. CONCLUSIONS: With these techniques, the position of the entrance pupil center relative to the excimer laser axis could be determined. Although the system is not fast enough to be used during surgery, it does allow quantification of centration and intraoperative motion after surgery.     

Wavefront-guided laser in situ keratomileusis: early results in three eyes

PURPOSE: Wavefront optical aberrations induced by refractive corneal surgery correction of myopia are probably the reason for deterioration of visual performance in some eyes after surgery. Customized photoablation of the cornea to correct both the sphero-cylindrical refractive error as well as individual optical aberrations may improve postoperative visual acuity and visual performance. METHODS: In 3 eyes of 3 patients the wavefront deviations were measured by means of an aberrometer of the Tscherning-type. Based on these measurements an ablation pattern was determined and applied during a LASIK procedure using a Wavelight Allegretto scanning spot excimer laser with a spot size of 1 mm and a laser repetition rate of 200 Hz. The 3 eyes are part of a prospective study on wavefront-guided LASIK started in July 1999. RESULTS: At 1 month after LASIK, all 3 eyes had gained up to 2 lines of best spectacle-corrected visual acuity. Best spectacle-corrected visual acuity improved to 20/10 in all 3 eyes, uncorrected visual acuity was 20/10 in two eyes, and 20/12.5 in 1 eye 1 month postoperatively. The wavefront deviations were reduced by 27% on average. At 3 months, best spectacle-corrected visual acuity was 20/10 in 2 eyes and 20/12.5 in 1 eye. CONCLUSION: Wavefront-guided LASIK is a feasible approach in refractive corneal surgery. Optimized ablation patterns may further improve the visual results.     

Ablation centration in myopic laser in situ keratomileusis. comparing the Visx S3 ActiveTrak and the Visx S2

PURPOSE: To compare ablation centration and outcome measurements in myopic laser in situ keratomileusis (LASIK) using the eye-tracking Visx S3 ActiveTrak and the nontracking Visx S2 excimer lasers. SETTING: University-based refractive surgery practice. METHODS: In a retrospective study, 71 consecutively treated myopic eyes that had LASIK with the Visx Star S3 ActiveTrak were compared to 71 control-matched eyes treated with the Visx Star S2 without pupil tracking. Primary outcome variables including ablation centration, uncorrected visual acuity, best spectacle-corrected visual acuity, manifest refraction, complications, and induced cylinder analyzed by vector analysis were evaluated 3 months postoperatively. RESULTS: The myopia ranged from -1.50 to -11.25 diopters (D) and the cylinder, from +0.25 to +2.75 D. Ninety-four of 142 eyes (66%) were available for analysis at 3 months; 50 eyes could be used to analyze ablation centration. At 3 months, the mean decentration of the ablation zone from the entrance pupil was 0.22 mm +/- 0.20 (SD) in tracked eyes (n = 25) and 0.21 +/- 0.26 mm in nontracked eyes (n = 25) (P =.88). Three eyes (12%) in the tracked group were decentered 0.5 to 1.0 mm, and 1 eye (4%) in the nontracked group was decentered more than 1.0 mm. All other eyes were decentered less than 0.5 mm. There was an association in the tracked group between greater decentrations and higher levels of myopia (r = 0.67), but this association did not exist in the nontracked group (r = -0.03). CONCLUSION: Comparable ablation centration as well as visual and refractive outcomes can be achieved with and without active eye tracking during myopic and astigmatic myopic LASIK.     

Laser in situ keratomileusis to correct hyperopic shift after radial keratotomy

PURPOSE: To assess the safety and efficacy of excimer laser in situ keratomileusis (LASIK) to correct hyperopic shift following radial keratotomy (RK). SETTING: Ophthalmic Health Center, Tel Aviv, Israel. METHODS: The study comprised 15 eyes of 12 patients who had uneventful RK and subsequently developed a hyperopic shift. Laser in situ keratomileusis was performed using the Chiron Automated Corneal Shaper and the Nidek EC-5000 excimer laser with 5.5 mm central and 7.5 mm peripheral ablation zones. The corneal flap was 160 microm in thickness and 8.5 mm in diameter. The refractive correction corresponded to the patients' refractive errors. RESULTS: The mean time after RK was 10.46 years +/- 2.21 (SD) and the mean follow-up after LASIK, 7.3 months (range 1 to 42 months). The mean spherical equivalent refraction was corrected from +3.08 +/- 1.02 diopters (D) to -0.16 +/- 0.73 D after LASIK. At the last examination, 12 eyes (80%) had a refractive error within +/-1.00 D of emmetropia and an uncorrected visual acuity of 20/40 or better. No wound dehiscence, epithelial ingrowth, or other significant complication developed in any eye. CONCLUSIONS: Early postoperative results of the correction by LASIK of a hyperopic shift after RK are encouraging, but long-term studies of a larger population group are required to evaluate the method's clinical value.     

Separate effects of the microkeratome incision and laser ablation on the eye's wave aberration

PURPOSE: To study the optical changes induced by the microkeratome cut, the subsequent laser ablation, and the biomechanical healing response of the cornea in normal laser in situ keratomileusis (LASIK) eyes. DESIGN: Prospective randomized clinical trial. METHODS: A Hansatome microkeratome was used to cut a corneal flap in one eye (study eye) of 17 normal myopic patients and a subsequent laser ablation was performed 2 months after this initial microkeratome incision. Control eyes received conventional LASIK treatments at the latter time point. The wave aberration of both the study and contralateral control eyes were measured over a 6-mm pupil with a Shack-Hartmann wavefront sensor for all preoperative, postflap cut, and postablation visits. RESULTS: The eye's higher order aberrations had a small, but significant increase (P =.03) of approximately 30% 2 months after cutting a flap. No systematic changes were observed in nearly all Zernike coefficients from their preoperative levels at 2 months postflap cut. A significant difference between the study and control eyes was observed for one trefoil mode, Z(3)(3) (P =.04). CONCLUSIONS: There was a wide variation in the response of individual Zernike modes across patients after cutting a flap. The majority of spherical aberration induced by the LASIK procedure seems to be due to the laser ablation and not the microkeratome cut. In addition, the total and higher order root mean square of wavefront errors were nearly identical for both the study and control eyes 3-months after the laser ablation, indicating that a procedure in which the incision and the ablation are separated in time to better control aberrations does not compromise the outcome of a conventional LASIK treatment.     

Comparison of videokeratographic functional optical zones in conductive keratoplasty and laser in situ keratomileusis for hyperopia

PURPOSE: To compare the videokeratographic functional optical zone of eyes treated with conductive keratoplasty to eyes treated with laser in situ keratomileusis (LASIK) for hyperopia. METHODS: Sixteen eyes treated with conductive keratoplasty for hyperopia were retrospectively evaluated to determine the size of the videokeratographic functional optical zone. The functional optical zone of these eyes was compared to the functional optical zone of 16 eyes that underwent LASIK for hyperopia with the VISX S2 excimer laser, for comparable amounts of hyperopia. The functional optical zone was measured at the edge of central corneal steepening and paracentral flattening on videokeratography 3 to 6 months after surgery. RESULTS: The functional optical zone after surgery measured an average of 5.6 mm horizontally and 5.6 mm vertically in the conductive keratoplasty eyes, and 4.7 mm horizontally and 5.1 mm vertically in the hyperopic LASIK eyes (P<.001 and P<.005). The mean functional optical zone area was 31.1 mm2 in the conductive keratoplasty eyes and 24.6 mm2 in the hyperopic LASIK eyes (P<.001). The functional optical zone created by conductive keratoplasty had more uniform central steepening and less peripheral blending than the functional optical zone created by hyperopic LASIK. CONCLUSION: Conductive keratoplasty was effective at creating central steepening in the cornea. The functional optical zone resulting from conductive keratoplasty was significantly larger than that obtained with hyperopic LASIK using the VISX S2 excimer laser.     

Laser in situ keratomileusis for residual hyperopic astigmatism after conductive keratoplasty

PURPOSE: To report a case of laser in situ keratomileusis (LASIK) in a patient with previous conductive keratoplasty. METHODS: A 48-year-old man underwent conductive keratoplasty for low hyperopic astigmatism (manifest refraction OD: +2.25 -0.50 x 77 degrees; OS: +2.50 -0.50 x 105 degrees). Three months postoperatively, UCVA was 20/25 and BSCVA was 20/20 in both eyes; manifest refraction OD: -0.25 -0.75 x 110 degrees; OS: +0.75 -0.75 x 50 degrees. Sixteen months after the operation, regression of refractive outcome was (manifest) OD: +1.75 -1.25 x 90 degrees; OS: +2.50 -0.50 x 85 degrees; UCVA was 20/40 in the right eye and 20/63 in the left eye and BSCVA was 20/20 in both eyes. LASIK was performed for hyperopic regression in the left eye using an automated microkeratome (Alcon SKBM, 130-microm plate; Aesculap-Meditec MEL 70 excimer laser). RESULTS: LASIK was uneventful and no intraoperative or postoperative complications related to the previous conductive keratoplasty procedure or LASIK were observed. Three months after LASIK and 19 months after the initial conductive keratoplasty, the patient's left eye was emmetropic; UCVA was 20/20(-2), BSCVA was 20/20 and manifest refraction was +0.25 -0.25 x 35 degrees. There was a uniform increase in topographical steepening. Visual acuity, refraction and topographic findings remained unchanged at 6 months. CONCLUSIONS: Even though our experience is limited, treatment of hyperopia with LASIK in an eye with refractive regression following previous conductive keratoplasty resulted in a predicted refractive outcome, with no complications, and improvement in visual acuity at 6 months follow-up.     

Transepithelial photorefractive keratectomy mode using SCHWIND-ESIRIS excimer laser: initial clinical results

AIM: To evaluate postoperative pain, uncorrected visual acuity (UCVA), and cornea haze value after transepithelial photorefractive keratectomy (T-PRK) performed with aspherical ablation profile using SCHWIND ESIRIS excimer laser. METHODS: Retrospective case series. Fifty-nice eyes (32 patients) with myopia associated with or without astigmatism underwent phototherapeutic keratectomy (PTK) followed by photorefractive keratectomy (PRK) which performed by Optimized Refractive Keratecomy (ORK)-CAM software based on aspherical ablation profile using SCHWIND ESIRIS excimer laser. Postoperative pain scale was measured on a questionnaire through five levels. Haze was graded by five grades, and UCVA, manifest refraction spherical equivalent (MRSE) were analyzed. RESULTS: Mean pain level was (1.37±0.613) (range: 1 to 3), the mean time picking out the soft contact lens was (6.22±1.73) days, at 3 months, UCVA was 1.0 for 40 eyes (67.8%), 0.5 for all eyes (100.0%). The UCVA was significantly less than the preoperative best spectacle corrected visual acuity (BSCVA) (t=-2.84, P=0.006), haze value was (0.27±0.25), no patients had a haze grade up to 2. Mean MRSE was (0.76±0.96) diopter(D) by 3 months. CONCLUSION: The outcomes from this study show that using the SCHWIND ESIRIS aspherical ablation profile for transepithelial PRK has a good visual result. The primary advantage is related to a spherical ablation profile, automatically considers the ablation volume of the stroma and the accurate and smooth removal of the epithelium with PTK. Additional studies are needed to determine long-term outcomes.     

Corneal higher order wavefront aberrations after hyperopic laser in situ keratomileusis

PURPOSE: To evaluate the changes in corneal higher order wavefront aberrations after hyperopic laser in situ keratomileusis (LASIK). METHODS: In a prospective case series, 15 eyes of 12 patients who had hyperopic LASIK were evaluated. Corneal topography was obtained before and after hyperopic LASIK with a Nidek EC 5000 laser using 5.5/8.0 ablation zones. Using anterior corneal height data, the changes in corneal higher order wavefront aberrations were calculated. RESULTS: The surgery significantly increased both corneal coma-like aberration (preoperative/6 months postoperative, 0.054/0.147 [172% increase] for 3-mm pupil and 0.381/1.076 [182% increase] for 6-mm pupil) and corneal spherical-like aberration (preoperative/6 months postoperative, 0.039/0.067 [72% increase] for 3-mm pupil and 0.297/0.959 [223% increase] for 6-mm pupil). The surgery significantly decreased Zernike coefficient 12 and the polarity of corneal spherical aberration changed from preoperative positive value to negative postoperatively. For a 3-mm pupil, the achieved changes in spherical equivalent refraction significantly correlated with the induced changes in the corneal coma-like aberration (R = 0.629, P = .010), but not with those in corneal spherical-like aberration (R = 0.408, P=.133) or Zernike coefficient 12 (R = -0.301, P = .282). For a 6-mm pupil, the achieved changes in spherical equivalent refraction significantly correlated with the induced changes in the corneal spherical-like aberration (R = 0.862, P < .0001) and Zemike coefficient 12 (R = -0.872, P < .001) but not with those in corneal coma-like aberration (R = 0.449, P = .094). CONCLUSIONS: Hyperopic LASIK significantly increases corneal coma-like and spherical-like aberrations and changes corneal spherical aberration from a positive to negative value.     

Transepithelial photorefractive keratectomy mode using SCHWIND-ESIRIS excimer laser: initial clinical results

AIM: To evaluate postoperative pain, uncorrected visual acuity (UCVA), and cornea haze value after transepithelial photorefractive keratectomy (T-PRK) performed with aspherical ablation profile using SCHWIND ESIRIS excimer laser. METHODS: Retrospective case series. Fifty-nice eyes (32 patients) with myopia associated with or without astigmatism underwent phototherapeutic keratectomy (PTK) followed by photorefractive keratectomy (PRK) which performed by Optimized Refractive Keratecomy (ORK)-CAM software based on aspherical ablation profile using SCHWIND ESIRIS excimer laser. Postoperative pain scale was measured on a questionnaire through five levels. Haze was graded by five grades, and UCVA, manifest refraction spherical equivalent (MRSE) were analyzed. RESULTS: Mean pain level was (1.37±0.613) (range: 1 to 3), the mean time picking out the soft contact lens was (6.22±1.73) days, at 3 months, UCVA was 1.0 for 40 eyes (67.8%), 0.5 for all eyes (100.0%). The UCVA was significantly less than the preoperative best spectacle corrected visual acuity (BSCVA) (t=-2.84, P=0.006), haze value was (0.27±0.25), no patients had a haze grade up to 2. Mean MRSE was (0.76±0.96) diopter(D) by 3 months. CONCLUSION: The outcomes from this study show that using the SCHWIND ESIRIS aspherical ablation profile for transepithelial PRK has a good visual result. The primary advantage is related to a spherical ablation profile, automatically considers the ablation volume of the stroma and the accurate and smooth removal of the epithelium with PTK. Additional studies are needed to determine long-term outcomes.     

Laser in situ keratomileusis for recurrent hyperopia following laser thermal keratoplasty

PURPOSE: Laser thermal keratoplasty (LTK) has its main indication in the correction of hyperopia. However, regression of refractive effect following LTK is a limitation. Laser in situ keratomileusis (LASIK) may provide a good alternative to correct residual refractive errors. METHODS: Fifty hyperopic eyes with varying amounts of regression after LTK underwent LASIK. The Chiron Automated Corneal Shaper microkeratome was used to make a flap of 160 microm and laser ablation was performed with the Technolas 217 Planoscan excimer laser. Postoperative follow-up was 6 months. RESULTS: Mean spherical equivalent refraction improved from +2.92+/-1.60 D to +0.36+/-1.48 D. Mean best spectacle-corrected visual acuity changed from 0.78+/-0.14 before LASIK to 0.76+/-0.16 D 6 months after LASIK. Mean uncorrected visual acuity changed from 0.37+/-0.16 to 0.66+/-0.24. Forty-two percent (21 eyes) were within +/-0.50 D of intended correction, 60% (30 eyes) were within +/-1.00 D, and 76% (38 eyes) were within +/-2.00 D. After LASIK, confluent haze between previous LTK spots was observed in most eyes, as LASIK ablation took place at the sites of the LTK spots. CONCLUSIONS: LASIK after LTK is a good alternative for hyperopic regression. Predictability and efficacy are less than with primary LASIK for hyperopia, but the procedure is equally safe.     

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.