Myopic Laser In Situ Keratomileusis Research Articles

High-irradiance CXL combined with myopic LASIK: flap and residual stroma biomechanical properties studied ex-vivo

Background/aimsTo evaluate ex vivo biomechanical and enzymatic digestion resistance differences between standard myopic laser in-situ keratomileusis (LASIK) compared with LASIK+CXL, in which high-irradiance cross-linking (CXL) is added.MethodsEight human donor corneas...

Outcomes of the Haigis-L formula for calculating intraocular lens power in Asian eyes after refractive surgery

To report outcomes using the Haigis-L formula to calculate intraocular lens (IOL) power in Asian eyes with long axial lengths (ALs) that had previous myopic laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK). Singapore National Eye Centre, Singapore. Retrospective case series. Patients with ALs greater than 25.0 mm and previous myopic LASIK or PRK who had phacoemulsification were analyzed. The emmetropic IOL power was back-calculated using the 1-month postoperative manifest refraction and compared with the emmetropic IOL power calculated with the Haigis-L formula. The primary outcome measure was the mean arithmetic prediction error, defined as the difference between the actual postoperative refractive error and the intended formula-derived refractive target. Sixty-two eyes (52 patients) were analyzed. The mean arithmetic prediction error was -0.44 diopter (D) ± 0.98 (SD) and the mean absolute error, 0.87 ± 0.62 D. The mean arithmetic prediction error was -0.52 ± 0.96 D in eyes with an AL less than 27.0 mm and -0.36 ± 1.00 D in eyes with an AL of 27.0 mm or greater (P = .463). The predictability of being within ±0.50 D and ±1.00 D of target was 35.7% and 63.1%, respectively, overall; 31.6% and 60.5%, respectively, in eyes with an AL less than 27.0 mm; and 39.1% and 65.2%, respectively, in eyes with an AL of 27.0 mm or greater (P = .772). The Haigis-L formula was acceptably accurate in predicting and achieving target outcomes after phacoemulsification in Asian eyes with a long AL that had previous myopic LASIK or PRK. No author has a financial or proprietary interest in any material or method mentioned.

New algorithm for intraocular lens power calculations after myopic laser in situ keratomileusis based on rotating Scheimpflug camera data

To develop an algorithm to calculate intraocular lens (IOL) power for eyes with previous laser in situ keratomileusis (LASIK) for myopia based on data from a rotating Scheimpflug camera and to compare calculations with those of current formulas. East Valley Ophthalmology, Mesa, Arizona, USA. Observational case series. Relevant IOL calculation and postoperative refractive data were obtained for eyes of patients who had previous myopic LASIK and subsequent cataract surgery. Initial screening and correlation analysis identified Pentacam Scheimpflug keratometry (K) values appropriate for use in calculating a "best K" for IOL power calculations in these eyes. Error analysis identified other eye measures to improve results. Final results were compared with results from 9 other calculation methods available on the American Society of Cataract and Refractive Surgery (ASCRS) web site. The study obtained data from 101 eyes of 77 patients. More than 200 Scheimpflug K-formula combinations were evaluated for each eye. The true net power in the 4.0mm zone centered on the corneal apex provided the best adjusted K reading for IOL power calculation in the Shammas no-history formula. The final formula had good outcomes, with 34%, 66%, and 91% of eyes being within ±0.25 diopter (D), ±0.50 D, and ±1.00 D of the refractive target, respectively. These results compare favorably to the best formulas on the ASCRS web site. The no-history formula derived using the Scheimpflug device's true net power in the 4.0mm zone centered on the corneal apex appears to be an accurate method for determining IOL power after LASIK for myopia. Corroboration with additional data sets is suggested. Neither author has a financial or proprietary interest in any material or method mentioned.

Safety and efficacy of a hydrogel inlay with laser in situ keratomileusis to improve vision in myopic presbyopic patients: One-year results

To study the safety and efficacy of implanting a hydrogel corneal inlay (Raindrop Near Vision Inlay) concurrently with performing laser in situ keratomileusis (LASIK) to treat myopic presbyopia and to compare the results with results of the same treatment in emmetropic and hyperopic patients. Two private clinics, Tijuana and Monterrey, Mexico. Prospective nonrandomized clinical trial. Bilateral myopic LASIK was performed and a corneal inlay was concurrently implanted in the nondominant eye under a flap created using a femtosecond laser. Primary safety outcomes were the retention of corrected distance (CDVA) and near (CNVA) visual acuities. Efficacy was evaluated on the basis of uncorrected near (UNVA), intermediate (UIVA), and distance (UDVA) visual acuities. A patient questionnaire was used to assess the preoperative and postoperative incidence of visual symptoms, the ability to perform common tasks with no correction, and patient satisfaction with vision. Thirty eyes were enrolled. At each postoperative visit, the mean CDVA and CNVA were within one half line of preoperative measurements and no eye lost 2 or more lines of CDVA. The mean binocular UDVA, UIVA, and UNVA were better than 20/25 Snellen at all postoperative visits. By 6months, 93% of patients had a binocular Snellen acuity of 20/25 or better across all visual ranges. According to patient questionnaires, 1year after surgery, visual symptoms were at preoperative levels, 98% of all visual tasks could be easily performed without correction, and 90% of patients were satisfied or very satisfied with their overall vision. A hydrogel corneal inlay with concurrent LASIK was safe and effective for treating myopic presbyopia. Drs. Garza and Chayet are consultants to and investigators for Revision Optics, Inc.

Accuracy of corneal power measurements for intraocular lens power calculation after myopic laser in-situ keratomileusis

Purpose The aim of the study was to evaluate the accuracy of corneal power measurements for intraocular lens (IOL) power calculation after myopic laser in-situ keratomileusis (LASIK). Setting The study was conducted at the Faculty of Medicine, Alexandria University, Egypt. Patients and methods The study was conducted on 45 eyes that had undergone myopic LASIK previously. Corneal power was measured using manual keratometry, automated keratometry, IOLMaster, and Pentacam. Different hypothetical IOL power calculation formulas were used in each case. Results The steepest mean K value with manual keratometry (37.48 ± 2.86 D) followed by automated keratometry (37.31 ± 2.83 D) and the IOLMaster mean K value (37.06 ± 2.98 D) were steeper than any other mean K value measured by Pentacam. Using 4 mm Holladay equivalent K reading (EKR) with the double-K SRK/T formula, the refractive outcome was good, with 97.8% of cases within ± 2 D, 80.0% of cases within ± 1 D, and 42.2% of cases within ± 0.5 D. The best combination of formulas was 'Shammas-PL+double-K SRK/T using EKR 4 mm'. Conclusion Pentacam Scheimpflug imaging using EKR at 4 mm improved the accuracy of IOL power calculation in post-LASIK eyes. The best option is a combination of formulas. It is recommended to use the mean of the combination of 'Shammas-PL+double-K SRK/T with EKR 4 mm'.

Efficacy and Safety of Topical Timolol Eye Drops in the Treatment of Myopic Regression after Laser In Situ Keratomileusis: A Systematic Review and Meta-Analysis

Aims. The aim of this study was to assess the efficacy and safety of timolol in the treatment of myopic regression after laser in situ keratomileusis (LASIK). Methods. We searched MEDLINE, CENTRAL, EMBASE, China National Knowledge Infrastructure (CNKI), and Chinese Biological Medicine (CBM) from the inception to July 2015 for relevant randomized controlled trials that examined timolol therapy for myopic regression. The methodological quality of the studies included was assessed using the Revman 5.3 software. Results. We included six clinical trials involving 483 eyes in this review, including 246 eyes in treated group and 237 eyes in controlled group. We observed statistically significant improvements on the postoperative SE in the 3 months. However, the change of CCT was not statistically different between the control group and the experimental group. There were fewer cases of IOP, UDVA, and CDVA in treated group having significant difference from the controlled group. Conclusions. Topical timolol could be an effective treatment for reduction of myopic regression especially the spherical errors after myopic LASIK. Further RCTs with larger sample sizes for these trials are warranted to determine the efficacy and limitation for myopic regression after LASIK.

Functional outcome and patient satisfaction after laser in situ keratomileusis for correction of myopia and myopic astigmatism.

Purpose:The purpose was to evaluate subjective quality of vision and patient satisfaction after laser in situ keratomileusis (LASIK) for myopia and myopic astigmatism.Patients and Methods:A self-administered patient questionnaire consisting 29 items was prospectively administered to LASIK patients at the Yemen Magrabi Hospital. Seven scales covering specific aspects of the quality of vision were formulated including; global satisfaction; quality of uncorrected and corrected vision; quality of night vision; glare; daytime driving and; night driving. Main outcome measures were responses to individual questions and scale scores and correlations with clinical parameters. The scoring scale ranged from 1 (dissatisfied) to 3 (very satisfied) and was stratified in the following manner: 1-1.65 = dissatisfied; 1.66-2.33 = satisfied and; 2.33-3 = very satisfied. Data at 6 months postoperatively are reported.Results:This study sample was comprised of 200 patients (122 females: 78 males) ranging in age from 18 to 46 years old. The preoperative myopic sphere was − 3.50 ± 1.70 D and myopic astigmatism was 0.90 ± 0.82 D. There were 96% of eyes within ± 1.00 D of the targeted correction. Postoperatively, the uncorrected visual acuity was 20/40 or better in 99% of eyes. The mean score for the overall satisfaction was 2.64 ± 0.8. A total of 98.5% of patients was satisfied or very satisfied with their surgery, 98.5% considered their main goal for surgery was achieved. Satisfaction with uncorrected vision was 2.5 ± 0.50. The main score for glare was 1.98 ± 0.7 at night. Night driving was rated more difficult preoperatively by 6.2%, whereas 79% had less difficulty driving at night.Conclusion:Patient satisfaction with uncorrected vision after LASIK for myopia and myopic astigmatism appears to be excellent and is related to the residual refractive error postoperatively.

Comparison of Intraocular Pressure before and after Laser In Situ Keratomileusis Refractive Surgery Measured with Perkins Tonometry, Noncontact Tonometry, and Transpalpebral Tonometry.

Purpose. To compare the intraocular pressure (IOP) before and after Laser In Situ Keratomileusis (LASIK), measured by Diaton, Perkins, and noncontact air pulse tonometers. Methods. Fifty-seven patients with a mean age of 34.88 were scheduled for myopia LASIK treatment. Spherical equivalent refraction (SER), corneal curvature (K), and central corneal thickness (CCT) and superior corneal thickness (SCT) were obtained before and after LASIK surgery. IOP values before and after surgery were measured using Diaton, Perkins, and noncontact air pulse tonometers. Results. The IOP values before and after LASIK surgery using Perkins tonometer and air tonometers were statistically significant (p < 0.05). However, no significant differences were found (p > 0.05) for IOP values measured with Diaton tonometer. CCT decreases significantly after surgery (p < 0.05) but no statistical differences were found in SCT (p = 0.08). Correlations between pre- and postsurgery were found for all tonometers used, with p = 0.001 and r = 0.434 for the air pulse tonometer, p = 0.008 and r = 0.355 for Perkins, and p < 0.001 and r = 0.637 for Diaton. Conclusion. Transpalpebral tonometry may be useful for measuring postsurgery IOP after myopic LASIK ablation because this technique is not influenced by the treatment.

Influence of the difference between corneal and refractive astigmatism on LASIK outcomes using solid-state technology.

To evaluate the influence of the difference between preoperative corneal and refractive astigmatism [ocular residual astigmatism (ORA)] on outcomes obtained after laser in situ keratomileusis (LASIK) surgery for correction of myopic astigmatism using the solid-state laser technology. One hundred one consecutive eyes with myopia or myopic astigmatism of 55 patients undergoing LASIK surgery using the Pulzar Z1 solid-state laser (CustomVis Laser Pty Ltd, currently CV Laser) were included. Visual and refractive changes at 6 months postoperatively and changes in ORA and anterior corneal astigmatism and posterior corneal astigmatism (PCA) were analyzed. Postoperatively, uncorrected distance visual acuity improved significantly (P < 0.01). Likewise, refractive cylinder magnitude and spherical equivalent were reduced significantly (P < 0.01). In contrast, no significant changes were observed in ORA magnitude (P = 0.81) and anterior corneal astigmatism (P = 0.12). The mean overall efficacy and safety indices were 0.96 and 1.01, respectively. These indices were not correlated with preoperative ORA (r = -0.15, P = 0.15). Furthermore, a significant correlation was found between ORA (r = 0.81, P < 0.01) and PCA postoperatively, but not preoperatively (r = 0.12, P = 0.25). Likewise, a significant correlation of ORA with manifest refraction was only found postoperatively (r = -0.38, P < 0.01). The magnitude of ORA does not seem to be a predictive factor of efficacy and safety of myopic LASIK using a solid-state laser platform. The higher relevance of PCA after surgery in some cases may explain the presence of unexpected astigmatic residual refractive errors.

Long-term quality of life after posterior chamber phakic intraocular lens implantation and after wavefront-guided laser in situ keratomileusis for myopia

To compare the vision-related quality of life 5 years after Implantable Collamer Lens phakic intraocular lens (pIOL) implantation and after wavefront-guided laser in situ keratomileusis (LASIK) for myopia. Department of Ophthalmology, Kitasato University, Kanagawa, Japan. Retrospective case series. Quality of life was measured with the National Eye Institute Refractive Error Quality of Life instrument in consecutive patients 5 years after pIOL implantation or wavefront-guided LASIK to correct myopia. Phakic IOL implantation was performed in 48 patients and LASIK in 55 patients. The scores for activity limitations, symptoms, appearance, and satisfaction with correction were significantly higher in the pIOL group than in the LASIK group (P<.05, Mann-Whitney U test). No significant differences in other scores were observed between the 2 groups (P ≥.05). The scores for near vision and dependence on correction were significantly higher in the younger subgroup than in the older subgroup with both techniques. Phakic IOL implantation may offer significant vision-related quality-of-life advantages (eg, fewer activity limitations and symptoms and better appearance and satisfaction with correction) over wavefront-guided LASIK for myopia in the long term. Moreover, refractive surgery may provide a better quality of life in younger patients.

Evaluation of Orbscan II plus non-history double-K method in intraocular lens power calculation for patients after refractive surgery

To explore the accuracy of intraocular lens (IOL) power calculation with non-history method using the keratometric value derived from one zone of Orbscan II topography after laser in situ keratomileusis (LASIK). For this retrospective study, 20 eyes from 20 patients undergoing myopic LASIK were included from August 2008 to November 2011. Posterior corneal curvature in peripheral 7 to 10 mm fitting zone of postoperative cornea was measured with Orbscan II topography. The ratio between anterior cornea and posterior cornea was used to calculate the preoperative total corneal power of each eye. The predicted postoperative spherical equivalent was calculated by the calculated preoperative total corneal power, power of implanted IOL, refractive error before cataract surgery and eye length from IOL-Master into the double-K method for SRK-T formula. The predicted postoperative spherical equivalent was also calculated by double-K method for SRK-T formula with clinical history. The mean difference between actual and predicted postoperative spherical equivalent, i.e. mean absolute error (MAE), were compared. (1) Non-history method: MAE of 11 eyes was within ± 0.5 D (55%), MAE of 15 eyes within ± 1.0 D (75%) and MAE of all eyes within ± 2.0 D. (2) Clinical-history method: MAE of 10 eyes was within ± 0.5 D (50%), MAE of 14 eyes within ± 1.0 D (70%) and MAE of all eyes within ± 2.0 D. (3) Comparison of non-history and clinical-history methods: The MAE of non-history method was (0.61 ± 0.59) D and the MAE of clinical-history method (0.68 ± 0.55) D. Paired t-test showed no statistically significant difference between two methods (t = -1.248, P = 0.227). The non-history method using the keratometric value derived from one zone of Orbscan II topography after LASIK provides an accurate calculation of IOL power and it can be used as a substitute for incomplete clinical data.

In vivo confocal laser microscopy of morphologic changes after simultaneous LASIK and accelerated collagen crosslinking for myopia: One-year results

To evaluate the safety of corneal collagen crosslinking (CXL) combined with laser in situ keratomileusis (LASIK). Shinagawa LASIK Center, Tokyo, Japan. Case series. Bilateral myopic LASIK patients had unilateral accelerated CXL (KXL System) in the nondominant eye. After LASIK, riboflavin 0.1% was instilled in the residual stromal bed for 60 seconds. After the riboflavin was washed out and the flap placed in its original position, ultraviolet-A light (30 mW/cm(2)) was administered for 60 seconds. The LASIK-CXL eyes and the LASIK-only eyes were compared. The uncorrected (UDVA) and corrected (CDVA) distance visual acuities, manifest refraction spherical equivalent (MRSE), keratometry values, endothelial cell density (ECD), pachymetry, optical coherence tomography (OCT), corneal hysteresis (CH), corneal resistance factor (CRF), keratoconus match index (KMI), and 37 parameters from a dynamic bidirectional applanation device (Ocular Response Analyzer) were analyzed. Morphologic changes were evaluated using confocal microscopy. No significant differences in UDVA, CDVA, MRSE, ECD, dynamic bidirectional applanation readings (eg, CH, CRF, KMI), or 37 additional parameters were found between the 2 groups (P>.05). Increased hyperreflectivity and a demarcation line similar to that seen after CXL were observed in the LASIK-CXL eyes. The demarcation line (mean depth 200.04 μm ± 27.01 [SD]; range 178 to 278 μm) was present in 23 eyes (95.8%); the line was well defined in 2 eyes (8.3%) and faint in 21 eyes (87.5%). Combined LASIK-CXL was safe, causing insignificant corneal biomechanical and morphologic changes similar to those with CXL treatment only. No author has a financial or proprietary interest in any material or method mentioned.

Epithelial Remodeling After Femtosecond Laser-assisted High Myopic LASIK

The aim of this study was to evaluate the possible topographic epithelial profile thickness changes (remodeling) after high myopic femtosecond laser in situ keratomileusis (LASIK) with concurrent prophylactic high-fluence cross-linking (CXL) in comparison with standard femtosecond LASIK. Preoperative and 6-month postoperative 3-dimensional epithelial thickness distribution maps were investigated through clinical spectral domain anterior-segment optical coherence tomography in 2 groups of femtosecond laser-assisted myopic LASIK cases. Group A represented 67 eyes treated additionally with concurrent prophylactic CXL (LASIK-Xtra); group B represented 72 eyes subjected to stand-alone femtosecond LASIK. Optical coherence tomography measurements of the epithelial thickness over the center 2-mm-diameter disk, mid-peripheral 5-mm rim, and overall (the entire 6-mm-diameter disc area) were investigated. The comparison of matched myopic correction subgroups indicated statistically significant differences in the epithelial thickness increase specifically between high myopia subgroups. For example, in group A (LASIK-Xtra), the mid-peripheral epithelial thickness increase was +3.79 and +3.95 μm for the "-8.00 to -9.00 diopter" and "-7.00 to -8.00 diopter" subgroups, which compare with increased thickness in group B (stand-alone LASIK), of +9.75 μm (P = 0.032) and +7.14 μm (P = 0.041), respectively, for the same subgroups. Application of prophylactic CXL concurrently with high myopic LASIK operation results in a statistically significant reduced epithelial increase in comparison with stand-alone LASIK. This comparison is observed between matched high myopic correction subgroups. This difference may correlate with higher regression rates and/or may depict increased biomechanical instability in stand-alone LASIK.

Ray tracing software for intraocular lens power calculation after corneal excimer laser surgery

To evaluate the accuracy of intraocular lens (IOL) power calculations using ray tracing software in eyes after myopic laser in situ keratomileusis (LASIK). Twenty-four eyes of 17 cataract patients who underwent phacoemulsification and IOL implantation after myopic LASIK were analyzed retrospectively. The IOL power calculation was performed using OKULIX ray tracing software. The axial length was measured using the IOLMaster and keratometry data using TMS2N. The accuracy of the IOL power calculation using OKULIX was compared with those using the Camellin-Calossi, Shammas-PL, Haigis-L formulas and the double-K SRK/T formula using 43.5 diopters (D) for the Kpre. The mean values of the arithmetic and absolute prediction errors were 0.63 ± 0.85 and 0.80 ± 0.68 D, respectively. The arithmetic prediction error by OKULIX was a significant hyperopic shift of the distribution of the postoperative refractive errors compared to the Camellin-Calossi, Shammas-PL and Haigis-L formulas (P < 0.05), and the absolute prediction error showed no significant difference with other formulas. The prediction errors using OKULIX were within ± 0.5 D in 10 eyes (41.7 %) and within ± 1.0 D in 18 eyes (75.0 %). The percentages of eyes within ± 1.0 D using OKULIX were comparable to those obtained using the Camellin-Calossi, the Shammas-PL formulas and the double-K SRK/T formula using 43.5 D for the Kpre, and significantly (P < 0.05) higher than that obtained using the Haigis-L formula. IOL power calculations using OKULIX provided predictable outcomes in eyes that had undergone a previous myopic LASIK.

Change in keratometry after myopic laser in situ keratomileusis and photorefractive keratectomy

To compare the change in keratometry (K), spherical equivalent (SE), and visual acuity after myopic laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). Academic tertiary care center. Retrospective review. The postoperative K, SE, and uncorrected and corrected distance visual acuities were measured 6 months, 9 months, 1 year, 2 years, 3 years, 4 to 5 years, 6 to 7 years, and 8+ years postoperatively. A difference (Δ) for each variable was calculated from its 6-month postoperative baseline. The rates of change were grouped based on the magnitude of myopic correction (0.00 to 2.99 diopters [D]; 3.00 to 5.99 D; 6.00 to 8.99 D), type of surgery (LASIK versus PRK), and age (<34 years; 34 to 45 years; >45 years). Statistically significant differences were found in the rates of change between low and moderate corrections to high corrections for ΔKavg (P=.0472 and P=.0091, respectively) and ΔSE (both P<.0001). Statistically significant differences were found in the rate of change in ΔKavg between all 3 ages groups (P=.0330, P=.0051, and P<.0001) and in ΔSE between ages less than 34 years and 34 to 45 years to ages over 45 years (P=.0158 and P=.0015, respectively). There was no significant difference in the rate of change in ΔKavg and ΔSE between LASIK and PRK (P=.3599 and P=.9403, respectively). There was keratometric and refractive regression for myopic LASIK, with the rate of regression depending on treatment magnitude and age. No author has a financial or proprietary interest in any material or method mentioned.

Myopic Regression after Phakic Intraocular Lens Implantation and LASIK

In myopia, biometry including the axial length is important, along with the refractive data. We compared the rates of myopic regression 3 years after phakic intraocular lens (pIOL) implantation and laser in situ keratomileusis (LASIK) after matching the preoperative axial length in highly myopic eyes of Japanese patients. This retrospective nonrandomized study included 133 eyes of 84 patients with myopia exceeding -6.00 diopters (D) who underwent implantation of two iris-fixated pIOLs (pIOL group, 66 eyes/46 patients) or myopic LASIK (LASIK group, 67 eyes/38 patients) who were followed for more than 3 years postoperatively. The patient age, preoperative refraction, and preoperative axial length were matched between the study groups. There were no significant differences preoperatively between the groups in age, intraocular pressure, refraction, keratometry, or axial length. The mean regression values after 3 years compared with the 1-month postoperative refractions were -0.12 ± 0.47 (SD) D in the pIOL group and -0.82 ± 0.69 D in the LASIK group (p < 0.001). The differences in the mean regression rates between 1 and 12 months, 12 and 24 months, and 24 and 36 months of follow-up were, respectively, 0.09 ± 0.38 D, -0.11 ± 0.35 D, and -0.11 ± 0.30 D in the pIOL group and -0.57 ± 0.84 D, -0.24 ± 0.47 D, and 0.00 ± 0.53 D in the LASIK group (p < 0.001, p = 0.07, p = 0.15, respectively). There was a significant difference in myopic regression 3 years postoperatively between the groups matched for preoperative axial length in Japanese patients. This result has the potential to elucidate myopia in the future.

Laser in situ keratomileusis for astigmatism ≤ 0.75 Diopter combined with low myopia: a retrospective data analysis

BackgroundThis study examined the refractive and visual outcome of wavefront-optimized laser in situ keratomileusis (LASIK) in eyes with low myopia and compound myopic astigmatism ≤ 0.75 diopter (D).Methods153 eyes from 153 consecutive myopic patients (74 male, 79 female; mean age at surgery 40.4 ± 10.4 years) who had a preoperative refractive cylinder ≤ 0.75 D and a manifest sphere between -0.25 D and -2.75 D, and who had completed 4-month follow-up. Three subgroups defined by the magnitude of preoperative manifest refractive cylinder (0.25, 0.50, and 0.75 D) were formed. Manifest refraction, uncorrected and corrected visual acuity were assessed pre- and postoperatively. The astigmatic changes achieved were determined using the Alpins vector analysis.ResultsAfter 4 months (120.0 ± 27.6 days) of follow-up, a mean uncorrected distant visual acuity of 0.07 ± 0.11 logMAR and a mean manifest refraction spherical equivalent of -0.06 ± 0.56 D were found. There was no statistically significant difference in efficacy and safety between the preoperative cylinder groups. Astigmatic overcorrection for preoperative cylinder of ≤ 0.50 D was suggested by the correction index, the magnitude of error, the index of success, and the flattening index.ConclusionsLow myopic eyes with a preoperative cylinder of ≤ 0.50 D were significantly overcorrected with regard to cylinder correction when combined with low myopic LASIK. Accordingly, we are cautious in recommending full astigmatic correction for eyes with low myopia and manifest cylinder of ≤ 0.50 D.

Transepithelial photorefractive keratectomy with adjunctive mitomycin-C for correction of residual myopia after LASIK

Purpose The aim of the study was to evaluate the efficacy and safety of transepithelial photorefractive keratectomy (trans-PRK) with adjunctive mitomycin-C (MMC) over laser in-situ keratomileusis (LASIK) flaps for the treatment of residual myopia following LASIK. Materials and methods In this single-center, retrospective clinical study, 12 eyes of nine patients (mean age 32.67 ± 2.8 years) who were administered MMC (0.02%, 20 s) during trans-PRK for the treatment of residual myopic error with a mean spherical equivalent of -1.00 ± 0.69 D following myopic LASIK were evaluated. The retreatment procedures were performed after an average of 13.67 ± 1.15 months of primary LASIK using Schwind Amaris 500E excimer laser, with trans-PRK plate form. All patients underwent slit-lamp microscopy, manifest and cycloplegic refraction, Sirius 3D corneal analysis, merging Scheimpflug technology with Placido topography, pachymetry, pupillometry, and wavefront analysis preoperatively and postoperatively. All patients underwent follow-up on day 1, at 1 week, and at 1, 3, and 6 months. Results Mean time between LASIK and PRK retreatment was 19.2 months (range 13-39 months). No intraoperative or postoperative complications occurred during primary LASIK or trans-PRK retreatment. Mean spherical equivalent refraction of attempted correction with PRK was -1.58 D (range -0.50 to -2.25 D). By the end of sixth postoperative month, the average uncorrected visual acuity improved from 0.48 (range 0.15-0.7) to 0.7 (range 0.3-1.0). All eyes showed improvement in uncorrected visual acuity. Four eyes had subjective improvement of glare symptoms. None of the eyes in the cohort developed postoperative haze or any complications. Conclusion Trans-PRK with adjunctive MMC is a safe and effective option for correction of residual myopia following LASIK.

Repeatability of Corneal Epithelial Thickness Measurements Using Fourier-Domain Optical Coherence Tomography in Normal and Post-LASIK Eyes

To evaluate the repeatability of corneal epithelial thickness (ET) and corneal thickness (CT) measurements in normal eyes and laser in situ keratomileusis (LASIK)-treated eyes using optical coherence tomography (RTVue system). In 35 right eyes of 35 normal subjects and 45 right eyes of 45 subjects who underwent a myopic LASIK, corneal ET and CT were evaluated in 17 areas: (1) 1 central zone within a 0- to 2.0-mm diameter, (2) 8 paracentral zones from a 2.0- to 5.0-mm diameter, and (3) 8 peripheral zones from a 5.0- to 6.0-mm diameter. The repeatability was assessed using within-subject standard deviation (SD), coefficient of variation, and intraclass correlation coefficient. At the central and paracentral zones, respectively, the SD values were 0.7 μm and 0.6 to 0.9 μm in normal eyes and 0.7 μm and 0.8 to 1.7 μm in LASIK-treated eyes for ET, and 1.0 μm and 2.8 to 4.6 μm in normal eyes and 1.3 μm and 4.0 to 4.8 μm in LASIK-treated eyes for CT. At the peripheral zones, in normal and LASIK-treated eyes, respectively, the SD values ranged from 0.8 to 1.2 μm and 1.4 to 2.2 μm for ET, and 4.1 to 6.4 μm and 6.0 to 9.1 μm for CT. The coefficient of variation values were low and intraclass correlation coefficient values were high in both groups for both ET and CT measurements. The Optical coherence tomography produced excellent repeatability, especially at the central and paracentral zones up to a 5-mm diameter for both corneal ET and CT measurements.

Efficacy of Punctal Occlusion in Management of Dry Eyes after Laser In Situ Keratomileusis for Myopia

Purpose: To evaluate the effect of punctal plug use in preventing dry eye after laser in situ keratomileusis (LASIK).Materials and Methods: A randomized clinical trial at a tertiary eye care center, Riyadh, Saudi Arabia. Participants underwent LASIK for myopia in both eyes and a lower punctal occlusion in one eye only while the other eye served as control. Both eyes received the same postoperative medications except for lubricant duration (subject eye: four times per day for one week; control eye: four times per day for 6 months). Participants were evaluated at 1 week, 2, and 6 months after surgery for signs and symptoms of dry eye. The main outcome measures were visual acuity; ocular surface parameters; and Ocular Surface Disease Index questionnaire.Results: Seventy-eight eyes of 39 patients were included in this study. The Ocular Surface Disease Index scores of eyes with punctal plugs were better at all follow-up visits, and the differences between both eyes were statistically significant (1 week, p < 0.0001; 2 months, p < 0.0001; 6 months, p = 0.008). At the final follow-up visit, the percentage of normal eyes was higher in eyes with punctal plugs for all ocular surface parameters (Schirmer 1 test, 94.9%; tear breakup time, 77.8%; punctate epithelial keratitis score, 71.8%) compared to eyes without occlusion (Schirmer 1 test, 92.3%; tear breakup time, 58.3%; punctate epithelial keratitis score, 53.8%); however, such differences were not statistically significant.Conclusion: Punctal plug insertion after LASIK surgeries may minimize the need for frequent lubricant application and hence improve patient satisfaction.