Short-Term Clinical Results of Hyperopic LASEK in Korean Patients

PURPOSE: To evaluate short-term clinical outcomes following hyperopic laser-assisted subepithelial keratomileusis (LASEK) in Korean patients. METHODS: This retrospective study included 18 eyes of 10 patients who underwent hyperopic LASEK between May 2005 and March 2013 in Seoul National University Hospital. Visual acuity and spherical equivalent were evaluated preoperatively and at 1 and 3 months postoperatively. High order aberrations and contrast sensitivity were measured before and 3 months after the operation. Alternative prism cover test (APCT) was performed both preoperatively with correction and postoperatively without correction. RESULTS: The mean age of patients was 32 +/- 11 years and the mean spherical equivalent refractive error was -2.95 +/- 1.24 diopters (D). Uncorrected visual acuities were log MAR +0.17 +/- 0.15 and log MAR +0.14 +/- 0.15 at postoperative 1 month and 3 months, respectively and showed no significant difference in best corrected visual acuity (+0.25 +/- 0.30). Spherical equivalent was -0.22 +/- 1.22 D at 1 month and 0.38 +/- 0.91 D at 3 months postoperatively. In 6 patients who had esotropia before the operation, APCT was 7.83 +/- 3.60 prism diopters (PD) esotropia at distance with correction preoperatively and 4.67 +/- 5.65 PD at distance without correction postoperatively. Three patients (16.7%) showed delayed wound healing with 1 (5.56 %) having persistent corneal opacity without significant visual loss. CONCLUSIONS: The effect of LASEK may be comparable for correcting hyperopia and esotropia when compared with the effect of LASIK in previous reports; however, delayed wound healing may be a concern.

Clinical Results of Wavefront-guided LASIK

PURPOSE: To investigate and compare the clinical outcomes of wavefront-guided LASIK performed by 2 different laser platforms. METHODS: A retrospective analysis of consecutive cases of eyes that underwent wavefront-guided LASIK by using the VISX S4 CustomVue system and the Zyoptix Z100 system advanced personalized mode. All procedures were performed by one surgeon. Fifty-six eyes of 36 patients were included. Of the 56 eyes, 30 eyes underwent LASIK by using the VISX S4 CustomVue system (CustomVue group), and other 26 eyes underwent LASIK by using the Zyoptix Z100 system (APT group). Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), manifest refraction, contrast sensitivity, total high order aberration (HOA), spherical aberration (SA) and Q-value were recorded preoperatively and at 1 week, 1 and 3 months postoperatively. RESULTS: There was no statistically significant difference between two groups in terms of preoperative UCVA, BCVA, manifest refraction, high order aberrations, Q-value and contrast sensitivity. Induced amount of SA was significantly lower in CustomVue group than in APT group (p = 0.02). CONCLUSIONS: Wavefront-guided LASIK performed by 2 different laser platforms caused clinically acceptable outcomes including good visual acuity and contrast sensitivity through 3 months. Furthermore, LASIK performed by VISX S4 CustomVue system caused less SA at three months after operation.

Comparison of Refractive Outcomes of Broad Beam and Flying Spot Excimer Laser after Photorefractive Keratectomy

PURPOSE: To assess the refractive outcomes in photorefractive keratectomy (PRK) of two eximer lasers: Broad beam and Flying spot laser. METHODS: We compared the refractive outcomes of 74 eyes (group I) treated with a VISX 20/20(excimer laser (VISX Inc. USA) using broad beam laser with those of 96 eyes (group II) treated with a Technolas 217 C-Lasik(TM) (Bausch and Lomb, USA) using flying spot laser. Each patients had been followed up for more than 6 months after surgery. RESULTS: Corneal astigmatism at preoperation were 1.25 +/- 0.62D in group I and 1.03 +/- 0.51D in group II and at postoperative 6 months, decreased to 1.12 +/- 0.53D in group I and 0.60 +/- 0.83D in group II. Manifest refraction were outside +/- 1D of spherical lens or 0.5 D of cylinder lens in 23.6 % in group I and 13.5% in group II. CONCLUSIONS: We suggests that PRK using flying spot laser effectively more reduces corneal astigmatism and provided more satisfactory predictability in refractive results than that of broad beam laser.

Comparision of Clinical Results of Excimer Laser Correction of Myopia and Compound Myopic Astigmatism Using VISX 20/20B isionKeyTM / 영남의대학술지

PURPOSE: To compare the efficacy, predictability, stability and safety of excimer laser photorefracive keratectomy(PRK) for mypia and photoastigmatic refractive keratectomy(PARK) for compound myopic astigmatism. METHODS: Two-hundred-three eyes(118 eyes or =-7D spherical equivalent) received excimer laser correction for compound myopic astigmatism and 152 eyes(116 eyes or =-7D) for simple myopia. A VISX 20/20B VisionKeyTM excimer laser was used to perform either PARK or PRK. Visual acuity with and without correction, refraction, IOP, corneal haze, and topography were evaluated at 1, 3, 6, and 12 months postoperatively. All patients were followed up for more than 12 months. RESULTS: Postoperative refraction were generally stable after 3 months without significant early overcorrection. At 12 months, 110(94.8%) eyes that underwent PRK and 104(88.1%) eyes that underwent PARK achieved UCVA of 20/30 or better in the group who had lower than -7D correction. For eyes treated with -7D or more, these figures were 31(86.1%) eyes after PRK and 57(67.1%) eyes after PARK. The incidence of within 1D of plano refraction at 1 year follow-up were 97.4% after PRK and 93.2% after PARK in group who had lower than -7D correction. For eyes treated with -7D or more, there figures were 80.6% after PRK and 70.6% after PARK. CONCLUSIONS: Myopia with or without astigmatism was successfully treated in most of the eyes using PRK or PARK with VISX 20/20B VisionKeyTM excimer laser. The predictability and stability of the postoperative refraction during the first 12 months seem to be quite reliable. Futher improvement of excimer laser system and software should increase the clinical outcomes and safety of refractive procedures.

Clinical Result of 105 Cases Overcorrected Temporally after LASIK: 6 Months follow-up

This study aimed to evaluate the refractive and visual results of the cases temporally overcorrected after laser in situ keratomileusis (LASIK). Among 582 myopic eyes that underwent LASIK using VISX STAR from March 1997 to October 1998, 105 eyes were overcorrected more than one diopter (D) one week after LASIK. 105 eyes were divided into three groups according to their spherical equivalent (SE) at one week: Group l (> or = 3D, 9 eyes), group ll (2-2.9D, 14 eyes), and group lll (1-1.9D, 82 eyes).Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), SE, and complications were studied one day, one week, two months, and six months after LASIK. The mean preoperative SE was -11.17 +/-2.57D in group l,-9.40 +/-2.91D in group lland -8.09 +/-1.92D in group lll. At 6 months, the mean SE was 1.81 +/-1.61D, 0.04 +/-0.43D and -0.37 +/-0.76D in group l, ll and lll, respectively. The mean regression of SE from one day to six months was 1.85D, 2.27D and 1.73D in group l,ll and lll, respectively (p>0.05). The proportion of eyes that lost two or more lines of UCVA after LASIK compared to preoperative BCVA was 33.3% in group l, 10% in group ll, and 9.2% in group lll. There were central island (5 eyes), capsular wrinkling (3 eyes), free cap (1 eye), subepithelal metalic debris (1 eye), epithelial ingrowth (1 eye)as complications in all groups. With these results it might be concluded that hyperopia less than 3D one week after LASIK is temporary and disappears 6 months after surgery without any additional treatment, whereas hyperopia equal or more than 3D one week after LASIK still showed hyperopic refraction even after 6 months. Therefore, these eyes need further evaluation for the correction of hyperopia.

Delayed Corneal Epithelial Wound Healing after Excimer laser Photorefractive Keratectomy

The purpose of this study was to evaluate the occurrence of delayed epithelial healing(DEH) and the factors associated with it after excimer laser photorefractive keratectomy(PRK) and to assess whether there are any difference in the clinical outcomes between the eyes of DEH group and normal epithelial healing(NEH) group. This retrospective study was done in 554 consecutive eyes which had eximer laser PRK(VISX 20/20B WisionKey system with central island removal program) by one surgeon(S.B.L) between September 1994 and April 1997 at Yeungnam University Medical Center. Mean reepithelializion time of all 554 eyes was 3.1+/-1.3 days. Delayed epithelial healing beyond postoperative 5 and 7 days after exicimer laser PRK were noted in 30 eyes(5.4%) and 8 eyes(1.4%) of all 554 eyes, respectively. Mean reepithelialization time of DEH group was 7.1 days(range 5~12 days). Occurrence of DEH after excimer laser PRK was not depending on sex, age, laterality, amount of attempted correction(-6D or -6D), type of procedure(PRK vs. PARK), use of Maclof, the order of operation(type eye vs. second eye) or the type of soft ware(version 3.20 vs. 4.01)(All: p>0.05). At 6 months after surgery, 16 eyes(64%) of total 25 eyes of DEH group achieved UCVA of 0.7 or better, and 14 eyes(56%) were within +/-1D of emmetropia. In the NEH group. 349 eyes(84.7%) were UCVA of 0.7 or better, and 365 eyes(88.4%) were within +/-1D of emmetropa. There was statistically significant decrease in the clinical outcome of DEH group being compared with NEH group(p<0.05) In conclusion, prompt management for complete epithelial wound healing should be done in the cases of delayed epithelial healing after excimer laser PRK because it can cause the decrease in clinical outcome. Further studies assessing the effects of numerous topical medications, preservatives and software on epithelial healing after exicimer laser PRK would be performed.

Clinical Results of LASIK using VISX STAR in High Myopia

Laser in situ keratomileusis(LASIK) composed of corneal flap and excimer laser photorefractive keratectomy(PRK) has been used for correction of high myopia. Among many kinds of excimer laser, VISX STAR has advantages like correction of cylindrical astigmatism and prevention of central island. We evaluate the effects and clinical course of LASIK using SCMD microkeratome and VISX STAR on 105 myopic eyes under -7.00D from Dec. 1996 to July 1997. The range of refractory error was from -7.00D to -15.00D and age was from 21yrs to 44yrs(mean age was 28.6yrs). The attempted correction of refractory error was determined depending on cycloplegic refraction. We evaluated the change of uncorrected visual acuity, best corrected visual acuity, spherical equivalent, astigmatism, corneal topography before operation, one day, one week, two months, and six months after operation. Uncorrected visual acuity was improved from 0.05 to 0.77, whereas best corrected visual acuity was decreased slightly from 0.92 to 0.85. Spherical equivalent was changed from -10.07 to -0.38D. However, change of cylindrical error was from -1.22D to -1.06D. This difference was not statisyically significant(p>0.05). 105 high myopic eyes were divided into two groups, in which one group was from -7.00D to -10.00D and the other group was from -10.00D to 15.00D. These two groups were compared in the point of effect of LASIK on visual improvement and correction of refractory error, retrospectively. However, there was no statistically significant differences of clinical results between two groups. With these results, it was found that LASIK using VISX STAR would be an excellent procedure for visual improvement and correction of refractory error in high myopia. However, the methods and technology would be required to control underlying astigmatism in VISX STAR system.

Clinical Result of Excimer Laser Photoastigmatic Refractive Keratectomy Using VISX 20/20 B VisionKeyTM with Version 4.01 Software

Photoastigmatic refractive keratectomy (PARK) using VISX 20/20 B excimer laser with version 4.01 software was performed in 205 consecutive eyes of compound myopic astigmatism to assess the efficacy, predictability, and safety of excimer laser treatment of compound myopic astigmatism between September 1994 and June 1996. The mean preoperative manifest spherical equivalent refraction was -6.95+/-2.52D (range -1.13 to -15D) and the mean preoperative manifest cylindrical refraction was -1.25+/-0.76D (range -0.5 to -4.50D). The patients were followed from 6 months to 1 year (mean 9.19 months). At 1 year, 82(75.2%) of all 109 eyes receiving PARK were within 1D of plano refraction, and 88(80.7%) of all 109 eyes achieved uncorrected visual acuity of 20/30 or better. Postoperative refractions were stable after 3 months without significant early overcorrection. Mean postoperative astigmatism was -0.29+/-0.40D at 6 months and -0.24+/-0.42D at 12 months. Overall improvement of astigmatism was 75% at 6 months and 82% at 12 months by vector analysis using Alpins` method. In conclusion, PARK using VISX 20/20 B VisionKeyTM excimer laser with version 4.01 software appears to be effective in the treatment of compound myopic astigmatism with a relatively high degree of accuracy and safety. The predictability and stability of the postoperative refraction during the first 12 months seem to be quite reliable.