Refractive Surgery Unit Research Articles

Impact of First Eye Cataract Surgery on Quality of Life

Cataracts are the second leading cause of visual impairment and the first cause of blindness, both globally and Indonesia. Cataracts do not only reduce vision but also the quality of life of the patients. Cataract surgery of at least one eye is expected to improve the patient's visual function and quality of life. This study aimed to assess the quality of life of patients with bilateral senile cataracts after the first eye surgery compared to people with normal vision. This was a cross-sectional study on 75 patients who underwent their first eye cataract surgery at the Cataract and Refractive Surgery Unit and 75 people with normal vision who visited the Refraction, Contact Lens, and Low Vision Unit of the National Eye Center of Cicendo Eye Hospital during the period of March-June 2020. The quality of life assessment was conducted through interviews using the National Eye Institute Visual Function Questionnaire-25. The non-inferiority test with a margin of 20% was performed. The mean age of the subjects was 63.49 years with no difference in the proportion of gender. Presenting visual acuity of binoculars after the first cataract surgery was 0.26 LogMAR and normal vision was 0.07 LogMAR. With a margin of 20%, the patient's quality of life after the first cataract surgery was not inferior to the normal vision subjects (d = -2.45% (95% CI -6.3% to 1.4%).) Hence, patients' quality of life after the first cataract surgery is not inferior to those with normal vision.

Higher-order aberrations following wavefront-guided photorefractive keratectomy and laser in situ keratomileusis

Background: We aimed to evaluate higher-order aberrations (HOAs) following wavefront-guided photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) in patients with myopia and myopic astigmatism.
 Methods: This retrospective observational case-control study included patients who underwent wavefront-guided PRK (40 eyes of 20 patients) or LASIK (40 eyes of 20 patients) between August 2018 and November 2018 at the refractive surgery unit of Kayseri City Hospital Eye Clinic, Turkey. The corrected distance visual acuity (CDVA), manifest refraction, corneal topography, and HOAs were evaluated preoperatively and 3 months postoperatively in all patients.
 Results: The mean age ± standard deviation (SD) was 27.13 ± 5.54 years and 29.10 ± 4.38 years in the PRK and LASIK groups, respectively (P = 0.06). Both groups had a mean CDVA of 1.00. The mean ± SD of spherical and spherical equivalent values was -2.09 ± 1.56 diopter (D) and -3.03 ± 1.72 D in the PRK group and -2.23 ± 1.69 D and -3.35 ± 1.71 D in the LASIK group, respectively (P = 0.58). When the preoperative and postoperative HOAs and root mean square (RMS) values (for a 6-mm pupil diameter) were compared in the PRK group, a significant difference was found in vertical coma and total RMS values (P = 0.003 and P ˂ 0.001, respectively); in the LASIK group, there was a significant difference in preoperative and postoperative vertical coma and total RMS values (P = 0.0.001 and P ˂ 0.001, respectively). There was no significant difference in preoperative and postoperative vertical coma values between the two groups (P = 0.735 and P = 0.583, respectively).
 Conclusions: In terms of HOAs, total RMS values decreased significantly and vertical coma values increased significantly at 3 months postoperatively in both PRK and LASIK groups. However, there were no differences between the two groups.

Results of laser enhancement for residual myopia after primary laser in situ keratomileusis.

PURPOSE:The purpose of the study is to evaluate and analyze the results and outcomes after laser enhancement for residual myopia after primary laser in situ keratomileusis (LASIK).MATERIALS AND METHODS:This retrospective interventional consecutive case series clinical study was performed on 112 consecutive eyes (82 patients) that had undergone primary LASIK before the enhancement procedure. The study was done in the Refractive Surgery Unit in Yemen Magrabi Hospital between 2006 and 2014. The retreatment was for residual myopia with or without astigmatism. Either the original flap was lifted or surface ablation was performed. Parameters evaluated were uncorrected visual acuity (UCVA) and best spectacle-corrected visual acuity (VA), spherical equivalent (SE) refraction, corneal topography, and pachymetry. Complications after laser enhancement were also evaluated.RESULTS:Mean age of the study group was 26.72 ± 6.89 years (range from 18 to 44 years). Males accounted for 37/82 (45.1%) and females for 45/82 (54.9%). The right eye was treated in 67/112 (59.8%) and the left eye in 45/112 (40.2%). Before primary LASIK, the mean SE (MSE) was −5.78 ± 1.89 D. Before enhancement, the MSE was −1.32 ± 0.61 D (range −3.25 D to −0.50 D), and none of the eyes had an UCVA of 20/40 or better. Twelve months after retreatment, the percentage of eyes having UCVA of 20/40 or better increased to 67.9% (76 of 112). There were no vision-threatening complications seen.CONCLUSION:Retreatment or enhancement after LASIK surgery by lifting the original flap or surface ablation is a safe and effective method for the treatment of regressed or undercorrected myopia. The risk of postoperative complications is very minimal.

Anterior Segment Optic Coherence Tomography Changes Before and After Phacoemulsification in Primary Open-Angle Glaucoma.

Objectives:The goal of this study was to compare measurements of values such as the anterior chamber angle (ACA), thickness of the iris, thickness of the cornea, and the angle-opening distance (AOD) of eyes with primary open-angle glaucoma before and after undergoing phacoemulsification with intraocular lens implantation using anterior segment optical coherence tomography (AS-OCT).Methods:The data of 49 eyes of 39 glaucoma patients who presented at the Cataract and Refractive Surgery Unit of the Ophthalmology Clinic of , University of Health Sciences, Istanbul Traning and Research Hospital between December 2014 and May 2016 were included in the study. All of the patients were examined with AS-OCT. All of the preoperative and postoperative data were evaluated statistically using a paired t-test and the Wilcoxon test. A statistical significance level of alpha was accepted as p<0.05.Results:The AS-OCT measurements of 39 patients (22 women and 17 men) with primary open-angle glaucoma were included in the study. The median age of the total population was 67±8years. No statistically significant difference was found between preoperative and postoperative measurements of the corneal thickness (p=0.480). However, there was a statistically significant difference between measurements of the ACA, AOD (500μm and 750μm), thickness of the iris curvature, anterior chamber depth, and trabecular-iris space area before and after the operation (p<0.001). Intraocular pressure (IOP) levels decreased significantly in the first and third months after surgery (p=0.019; p=0.003, respectively).Conclusion:This study with AS-OCT imaging has confirmed after phacoemulsification and intraocular lens implantation in patients with glaucoma, the angle of the anterior chamber grows wider. As a result, IOP decreases and becomes easier to control.

Prevalence of Keratoconus in a Refractive Surgery Population.

Objective This study examined the prevalence of keratoconus among patients who were interested in undergoing refractive surgery. Corneal tomography measurements were used to help detect keratoconus. Methods Adult subjects who presented to the private hospital Cataract and Refractive Surgery Unit (Abha, Saudi Arabia) for refractive surgery evaluation were considered for inclusion in this cross-sectional, retrospective study. All subjects were from the Aseer province, a southern, high-altitude region in Saudi Arabia, and presented between January and December 2017. The incidence of keratoconus and other refractive surgery contraindications were examined. Results A total of 2931 patients were considered for inclusion in analyses. Of these, 2280 patients (77.8%) were not candidates for refractive surgery. These 2280 patients had a mean age of 24.1 ± 6.6 years and 1231 patients (54.0%) were male. Of the subjects who did not undergo refractive surgery, 548 (24%) had keratoconus, 400 (17.5%) were keratoconus suspects, 344 (15.1%) had thin corneas, 321 (14.1%) had high myopia, and 52 (2.3%) had a high astigmatism. An additional 479 subjects (21%) were candidates for refractive surgery, but chose not to undergo a procedure. Conclusion The incidence of keratoconus in Saudi Arabian refractive surgery prospects was 18.7%. Keratoconus was the most common reason for not performing refractive surgery and accounted for 24.0% of cases in which surgery was not performed.

Role of laser refractive surgery in cross-subsidization of nonprofit humanitarian eyecare and the burden of uncorrected refractive error in Nepal: Pilot project

To establish a refractive surgery unit at Tilganga Institute of Ophthalmology through support from international donations and provide knowledge transfer for doctors and management to make the unit self-sustaining, nonprofit laser refractive surgery, and financial support for other eyecare projects at Tilganga. Tilganga Institute of Ophthalmology, Kathmandu, Nepal. Retrospective study. A foundation was created to establish a refractive surgery unit using a cost-recovery model; that is, patients are charged according to their financial status to cover running costs, patients without funds to pay for surgery, and other eyecare projects for the underprivileged population of Kathmandu, Nepal. Donations were obtained to fund refurbishment within Tilganga Hospital and purchase equipment and technology. A Nepalese surgeon was selected from Tilganga and completed an 8-month fellowship and proctorship of the first series of surgeries. The refractive surgery unit was opened in January 2012, and the cost-recovery model was evaluated up to December2016. During the period evaluated, 74.8% of patients were treated at full cost, 17.2% at subsidized cost, and 8.6% free of charge. The refractive surgery unit generated a profit representing 28% of the running cost in this period, which was used to reduce the deficit of the main hospital. Surgical outcomes achieved were comparable to those reported by groups in the developed world. A self-sustaining nonprofit laser refractive surgery clinic, operating with high quality, was successfully implemented supported by international donations for initial setup costs and a cost-recovery model thereafter.

Quality control outcomes analysis of small-incision lenticule extraction for myopia by a novice surgeon at the first refractive surgery unit in Nepal during the first 2 years of operation

To evaluate the outcomes of small-incision lenticule extraction for myopia using the Visumax femtosecond laser at the first refractive surgery unit in Nepal during the first 30 months of operation. Tilganga Institute of Ophthalmology, Kathmandu, Nepal. Retrospective noncomparative case series. Consecutive myopic small-incision lenticule extraction procedures by a fellowship-trained surgeon were evaluated. Inclusion criteria were a preoperative spherical equivalent (SE) refraction up to -10.00 diopters (D) and corrected distance visual acuity (CDVA) of 20/20 or better. Outcomes analysis using the Standard Graphs for Reporting Refractive Surgery was performed over a 3-month follow-up. Three-month data were available for 1396 eyes. The mean attempted SE was -5.78 D ± 1.81 (SD) (range -0.96 to -10.00 D) and the mean cylinder, 0.79 ± 0.69 D (range 0.00 to 5.25 D). Postoperatively, the mean SE relative to target was -0.28 ± 0.29 D (range -1.31 to +1.50 D) and was within ± 0.50 D in 80% of eyes and ± 1.00 D in 99% of eyes. The uncorrected distance visual acuity was 20/20 or better in 95% of eyes and 20/25 or better in 99% of eyes. One line of CDVA was lost in 2% of eyes; no eye lost 2 or more lines. There was a small improvement in contrast sensitivity (P < .01). The outcomes of myopic small-incision lenticule extraction up to -10.00 D performed at the first refractive surgery unit in Nepal by a fellowship-trained surgeon with no corneal refractive surgery experience were as safe and effective as outcomes in previous studies. Dr. Reinstein is a consultant to Carl Zeiss Meditec AG and has a proprietary interest in the Artemis technology (Arcscan, Inc.) through patents administered by the Center for Technology Licensing at Cornell University, Ithaca, New York, USA. Drs. Pradhan and Carp have travel expenses to conferences paid by Carl Zeiss Meditec AG. No other author has a financial or proprietary interest in any material or method mentioned.

Correlation between apical protrusion in the Scheimflug imaging and Corneal Hysteresis and Corneal Resistance factor by Ocular Response Analyzer, among refractive non-keratoconic Egyptian patients.

IntroductionApical protrusion in the central 4-mm ring in the Scheimflug imaging (Pentacam), both for the anterior and posterior floats as well as Corneal Hysteresis and Corneal Resistance Factor by Ocular Response Analyzer (ORA), generally are considered important predictors for post-Lasik ectasia. The aim of this work was to find out if there is a statistically significant correlation between these different predictors and their correlation with the central corneal thickness for refractive non-keratoconic Egyptian patients trying to achieve a better decision and avoiding ectasia.MethodsThis case-control study involved 142 eyes (of 77 patients with various refractive errors) arriving at the refractive surgery unit in the Research Institute of Ophthalmology in Giza (Egypt) in 2014–2015 seeking excimer laser ablation. The flattest, steepest keratometry readings, central corneal thickness as well as the apical protrusion in the central 4-mm ring, both for the anterior and posterior floats, in microns were measured by Scheimflug imaging. The Corneal Hysteresis and Corneal Resistance Factor were measured by the ocular response analyzer. Statistical analysis was performed by SPSS, using the Pearson correlation test.ResultsThe spherical refractive error ranged from +7.00 to −13.00 diopters (−3.80 ± 2.89). The central pachymetry ranged from 494 to 634 μm (550.35 ± 32.13). For the central 4-mm ring, the apical protrusion ranged from 0 to +15 μ (6.93 ± 2.99) for the anterior float and from −3 to +20 μ (9.33 ± 4.55) for the posterior float. The Corneal Hysterisis (CH) ranged from 7 to 14.8 mmHg (10.18±1.44), while the Corneal Resistance Factor (CRF) ranged from 7.5 to 14.9 mmHg (10.58 ± 1.67). There was a strong positive correlation between the central corneal thickness and both Corneal Hysteresis (CH: r = 0.56, P ≤ 0.01) and Corneal Resistance Factor (r = 0.46, P ≤ 0.01). A significant correlation (P < 0.05, r = 0.15) existed between apical protrusion in the posterior float and the central corneal thickness. Also, significant negative correlation (P < 0.05, r = −0.12) existed between apical protrusion in the anterior float by pentacam and the Corneal Resistance Factor by ocular response analyzer.ConclusionsOur finding of a strong positive correlation between both Corneal Hysteresis and Corneal Resistance Factor and the Central corneal thickness being important for biomechanical corneal stability. The findings of this study also support using both machines preoperatively to decrease the risk of post-Lasik ectasia.

Safety and efficacy of wavefront-guided myopic laser in situ keratomileusis using a new wavefront sensor technology: First 100 cases

To evaluate the safety and efficacy of wavefront-guided laser in situ keratomileusis (LASIK) for the correction of low to high myopia and myopic astigmatism using data derived from a new-generation Hartmann-Shack aberrometer. Refractive Surgery Unit, Bordeaux Hospital University, France. Retrospective case series. This retrospective study analyzed the initial group of eyes treated with wavefront-guided LASIK for myopia and myopic astigmatism using the Visx S4IR excimer laser and wavefront data derived from a new Hartmann-Shack aberrometer (iDesign Advanced Wavescan aberrometer). Refractive (refraction and refractive accuracy) and visual outcomes (uncorrected [UDVA] and corrected [CDVA] distance visual acuities) were recorded 3 months postoperatively. The study included 100 eyes of 50 consecutively treated patients. The mean decimal UDVA improved from 0.1 ± 0.1 (SD) preoperatively to 1.1 ± 0.15 postoperatively (P < .01). A monocular UDVA of 20/16, 20/20, and 20/25 were achieved in 76.6%, 94.4%, and 96.6% of eyes, respectively. The postoperative manifest spherical equivalent was within ±0.5 diopter in all eyes. No eye lost 2 or more lines of CDVA, and 29.2% of the eyes gained 1 or more lines of CDVA. Wavefront-guided LASIK performed using data derived from the new Hartmann-Shack aberrometer was safe, effective, and predictable for treating myopia and myopic astigmatism. No author has a financial or proprietary interest in any material or method mentioned.

Laser in situ keratomileusis: epidemiology and risk factors of flap folds

AbstractPurpose Flap wrinkles can be seen in 0,2‐4% of LASIK cases. Our purpose is to evaluate flap folds through 7 femto‐second cases and make a review of the literature on the epidemiology.Methods Retrospective monocentric review of 822 eyes who had flap created with the IntraLase FS60 femtosecond laser one month follow up were included between January 2012‐January 2014 in the Ophthalmology and Refractive Surgery Unit, Percy Military Hospital. Patients had an exhaustive examination with uncorrected (UDVA) and corrected distance visual acuities, spherical equivalent and mean keratometry (Km) were compared preoperatively and postoperatively. Flap thickness were measured with SD‐OCT and optical aberrations on Zyoptix Wavefront System.Results 7 folds of 6 patients were observed (0.85% of LASIK procedures), 4 were horizontal, 1 vertical and 2 oblique. No trauma was found. All the folds involved the visual axis. Their UDVA was +0,2 logMAR (from +0,4 to 0). Mean spherical equivalent decreased from ‐4,9 D to ‐0,43 D, mean Km changed from 43 D to 39.75 D. Postoperative optical aberrations measured at 4.57 µm (+/‐ 2). Mean thickness measured to 120µm (+/‐ 8). The main causes are early trauma, flap desiccation and contraction, intraoperative misalignment, flap thinness, large photo‐ablation of myopia and cuts with microkeratome. The folds concern throughout its thickness and are the result of hyper‐hydration of proteoglycans, resulting in irregularity of Bowman's membrane and flap deformation.Conclusion Flap folds are a potentially sight‐threatening complication. Rigorous surgical technique, education and post‐operative follow‐up would reduce their frequency, identify and treat them quickly to increase visual performance.

Observational comparative study of different predictive scores of infraclinic keratoconus in refractive laser surgery in case of recused patients

AbstractPurpose INTRODUCTION : The surgical laser treatment of refractive disorders is becoming more and more prevalent. Preoperative evaluation means are multiple and all seem promising in the detection of infraclinic keratoconus. Our purpose was to compare the different scores. SETTING : Review of cases, ophthalmology and refractive surgery unit, Percy Military Hospital, Clamart, France.Methods MATHERIAL AND METHODS : Retrospective monocentric observational study, conducted between november 2013 and may 2014. Each patient benefited from an exhaustive corneal topography assessment : Pentacam® and a Belin/Ambrosio ehancement (P/B), Orbscan® and SCORE analyzer by Gatinel &amp; Saad (O/S), and an Ocular Response Analyzer (ORA). A systematic analysis of the following was conducted : the thinnest point of pachymetry (TP), the value of maximum posterior elevation (MPE), the I‐S ratio (IS), the maximum keratometry (K max), the presence of SRAX, and the enantiomorphism.Results RESULTS : 36 myopic patients, recused from laser refractive surgery, were included, or 72 eyes. Suspect cases added up to 31 patients for P/B, 32 for O/S, and 27 for ORA (or respectively 52, 55 and 40 eyes). There were 9 cases of discordance between the different scores. The averages were respectively : 502 +/‐ 47 µm for P, 26.81 +/‐ 7.46µm for MPE, 0.78 +/‐ 0.55 for IS, 44.6 +/‐ 1.8D for K‐max.Conclusion CONCLUSION : Each of the exams and indices studied led us to detect infraclinic keratoconus, but in discordant cases, a more detailed analysis of the topographic map remains essential.

Effects of mitomycin-C on tear film, corneal biomechanics, and surface irregularity in mild to moderate myopic surface ablation: Preliminary results

To assess the effect of mitomycin-C (MMC) on the tear film, corneal biomechanics, and surface irregularity in surface ablation (photorefractive keratectomy [PRK]) for low to moderate myopia. Refractive Surgery Unit, Farabi Eye Hospital, Tehran, Iran. Double-masked randomized clinical trial. In patients with spherical equivalent myopia of -0.75 to -3.87 diopters (D) and astigmatism up to -1.75 D, the first eye was randomly assigned to the application of MMC 0.02% or a balanced salt solution for 15 seconds. The fellow eye received the alternate in a masked fashion after excimer photoablation. The study enrolled 60 patients. In fellow eyes, the changes in the tear-film index were comparable 1 month and 6 months postoperatively. There was no significant difference in changes in total higher-order aberrations, spherical aberration, coma, or Q values (Pentacam HR) between fellow eyes at 1 month and 6 months. There was a trend toward a higher asymmetry index at 1 month; however, a statistically significant drop was observed at 6 months in the MMC group (P<.01). It was hypothesized that stromal remodeling was delayed, but better, in MMC-treated eyes. No haze was recorded at 6 months in either group. Use of MMC in PRK did not appear to contribute significantly to surface irregularity, transient tear-film dysfunction, or biomechanical weakening of the cornea compared with PRK without MMC. No author has a financial or proprietary interest in any material or method mentioned.

The clinical outcome and the indications of retropupillary fixation of Artisan®

The aim of the study was to determine the indications for surgical correction of aphakia and stability and complications following the combination of multiple procedures with retrofixation of Artisan® (Ophtec, Groningen, Netherlands). Seven patients who underwent retropupillary fixation of the intraocular lens (IOL) in the Cataract and Refractive Surgery Unit of Dubai Hospital from January 2012 to December 2012 were selected for the study. The study included one patient with aphakia following penetrating injury with pupillary abnormality, two patients with opaque hydrogel posterior chamber IOL (PCIOL) (with pseudophakic bullous keratopathy in one of these patients) and one patient each wth previous failed keratoplasty with anterior chamber IOL (ACIOL) and pupillary abnormality, aphakia following complicated cataract surgery, subluxated PCIOL with sunset syndrome and pseudophakic bullous keratopathy with ACIOL. All the patients underwent detailed eye examination and IOL calculation. Artisan insertion was combined with other surgical procedures in all of the patients and the patients were followed up postoperatively for a minimum of 6 months. There was improvement in vision in all patients. There was no significant increase in intraocular pressure (IOP) or postoperative inflammation, but one patient showed disenclavation of the haptic after 6 months. Retrofixation of IOL is one of the novel methods of correcting secondary aphakia of various causes. It is well tolerated in any age group and presents few complications. In addition, this procedure can be easily combined with other procedures such as penetrating keratoplasty, vitrectomy and anterior chamber reconstruction.

Refractive Outcomes and Quality of Vision Related to an Outbreak of Diffuse Lamellar Keratitis

To report the impact on visual function and corneal aberrations during an epidemic of diffuse lamellar keratitis (DLK). A retrospective, comparative, and consecutive case-control study was performed, involving 418 eyes operated between March and October 2007 in the refractive surgery unit of one center. Eyes were separated into groups: group 1 (DLK group) included 209 eyes that presented with DLK after LASIK and group 2 (control group) included 209 unaffected, consecutive eyes operated from the beginning of the outbreak. Refractive variables and corneal aberrations were compared between the two groups. Visual outcomes were significantly different when comparing control eyes and eyes with DLK grades 3 and 4, but not for eyes with DLK grades 1 and 2. Uncorrected distance visual acuity (UDVA) significantly improved from the third month after DLK was diagnosed (Kruskal-Wallis, P=.02). Corrected distance visual acuity (CDVA) did not decrease significantly with DLK grades 1 and 2 (preoperative CDVA vs 1, 3, and 6 months after diagnosis; Mann-Whitney, P>.05, respectively). At the end of follow-up, UDVA and CDVA were not significantly different between the two groups. Eyes suffering from DLK had significantly increased corneal aberrations, except for spherical and astigmatism aberrations, 3 months after being diagnosed (Kruskal-Wallis, P<.05); however, corneal aberrations were not significantly different between the DLK and control groups (Mann-Whitney, P>.05). The outbreak of DLK did not induce a significant decrease in global visual outcomes, except in severe cases, and postoperative corneal aberrations were not affected.

Reasons for Not Performing LASIK in Refractive Surgery Candidates in Yemen

To determine and analyze the reasons that laser in situ keratomileusis (LASIK) was not performed in patients who requested refractive surgical correction of their refractive errors. A retrospective observational study was performed in Yemen Magrabi Hospital between June 2005 and October 2006; the case records of 1596 new consecutive patients who presented for refractive surgery at our refractive surgery unit were reviewed. Data on the ocular status, refractive problems, and investigations performed were analyzed. The reasons for not performing LASIK in the cases that were rejected were recorded and analyzed. A total of 1191 patients (74.6%) were advised to have LASIK of the 1596 patients examined. LASIK was not advised in 405 patients (25.4%). The most common reasons for rejecting LASIK were suboptimal central corneal thickness (25.9%), high myopia >-11.00 D (17.0%), keratoconus (15.5%), cataract (11.4%), and suspicious corneal topography (forme fruste keratoconus) (9.4%). Patients who request refractive surgery have a variety of problems and attention must be given to these patients. Suboptimal corneal thickness, high amount of refractive error, and keratoconus were found to be the leading causes of not performing LASIK in Yemeni patients.

Severe corneal epithelial sloughing during laser in situ keratomileusis as a presenting sign for silent epithelial basement membrane dystrophy

To report the occurrence of large intraoperative epithelial sloughing during laser in situ keratomileusis (LASIK) as a first diagnostic sign for silent epithelial basement membrane dystrophy (EBMD). Refractive Surgery and Cornea Unit, Alicante Institute of Ophthalmology, Alicante, Spain. In this retrospective case series, the medical records of all patients with large corneal epithelial sloughing/defects during LASIK from January 1995 to December 2004 were reviewed. All patients who presented normal corneas before LASIK and EBMD changes after LASIK were included in this study. The surgical procedures and postoperative course were recorded. The follow-up period was 12 months for all patients. Eleven eyes of 6 patients were included. The mean age was 35 years +/- 6.1 (SD). Mean preoperative uncorrected visual acuity (UCVA) was 20/500 (0.04 +/- 0.02); 12 months after surgery, mean UCVA increased to 20/27 (0.74 +/- 0.21). There was a significant decrease in best spectacle-corrected visual acuity 1 month after surgery. One year postoperatively, 10 of 11 eyes (91%) were within +/-1.00 diopter of emmetropia. Postoperatively, clinical manifestations of EBMD were observed in all eyes and complications were common. In the early postoperative period, diffuse lamellar keratitis was observed in 6 of 11 eyes (54.5%) and flap microfolds were noted in 2 of 11 (18.2%). One year after surgery, epithelial ingrowth was present in 8 of 11 eyes (72.7%) and flap melting was noted in 4 of 11 (36.4%). Occurrence of large intraoperative epithelium sloughing/defects during LASIK might be a diagnostic sign for subclinical EBMD. These patients are predisposed to multiple postoperative complications. Because of the high risk for epithelial sloughing in the second eye, LASIK should not be performed.

Are intracorneal rings still useful in refractive surgery?

This article reviews the latest data published and presented at international meetings about the use of intracorneal ring segments in corneal and refractive surgery. The long-term data on intracorneal ring segments in the correction of low to moderate myopia indicate that they seem clearly comparable with laser in-situ keratomileusis, the most common refractive procedure worldwide. There is increasing interest in the use of intracorneal ring segments for the treatment of some complications after laser in-situ keratomileusis and for the control of some degrees of primary corneal ectatic disorders such as keratoconus and pellucid marginal degeneration. Intracorneal ring segments are and will be useful in several corneal and refractive abnormalities. Concern still exists about their predictability and the long-term effects of their use in primary and secondary ectasia.

Corneal flap thickness and topography changes induced by flap creation during laser in situ keratomileusis

To determine the corneal flap thickness profile produced by 3 microkeratomes and the topographic changes induced by flap creation in laser in situ keratomileusis (LASIK). Cornea and Refractive Surgery Unit, Instituto de Microcirugia Ocular de Barcelona, Autonoma University, Barcelona, Spain. In this prospective consecutive nonrandomized comparative study, patients were divided into 2 groups. In Group 1 (75 eyes), 3 microkeratomes were used: Moria LSX One, Moria M2, and Amadeus (AMO); 25 eyes per microkeratome. Pachymetry was measured with a DGH pachymeter in the center of the cornea and 3.0 mm from the center at 4 cardinal points (superior, inferior, nasal, and temporal; 3 measurements at each point) before and after the cut. The flap thickness in each sector was calculated by subtracting the mean post-flap corneal thickness from the mean pre-flap corneal thickness. In Group 2 (33 eyes), the M2 microkeratome with a 130 microm plate was used to create a superotemporal hinged flap (9 eyes) or a superonasal hinged flap (24 eyes). The topographic change induced by the microkeratome cut was evaluated using 4 sequential data acquisitions by the Keratron Scout topographic unit (Optikon) before and immediately after the cut (before laser ablation). Cardinal and oblique astigmatism and change in the axis were calculated by vectorial analysis of the simulated keratometry. Topographic Zernike analysis was performed in a subgroup. With the LSX One microkeratome, the mean flap thickness was 151.7 microm centrally, 161.9 microm superiorly, 151.4 microm inferiorly, 156.1 microm temporally, and 167.5 microm nasally. There was no statistically significant difference between the areas studied (P<.05). With the M2, the mean flap thickness was 131.7 microm centrally, 155.5 microm superiorly, 146.7 microm inferiorly, 143.7 microm temporally, and 160.5 microm nasally. There was a statistically significant difference between flap thickness centrally and in the other areas (P>.05). With the Amadeus microkeratome, the mean flap thickness was 140.0 microm centrally, 152.5 superiorly, 128.5 microm inferiorly, 145.0 microm temporally, and 147.0 microm nasally. Statistically significant differences (P>.05) were found in the 4 sectors of the flap. With vectorial analysis, there was no statistically significant difference between superonasal and superotemporal hinge placement in the cardinal and oblique components but there was a statistically significant difference in the axis change with both placements (P>.05). The LSX One microkeratome was the most predictable. A significant difference was noted in all sectors except superiorly with the M2 and in all sectors with the Amadeus. No differences between nasal and superior hinge placement were found with the M2. Topographic Zernike analysis demonstrated a difference in the orientation of the induced coma as a function of hinge position.

Corneal aberrations after astigmatic keratotomy combined with laser in situ keratomileusis

Purpose: To evaluate the optical aberrations in the cornea before and after astigmatic keratotomy (AK) combined with laser in situ keratomileusis (LASIK) in a group of patients with high myopic astigmatism. Setting: Refractive Surgery Unit, NISA Hospital Virgen del Consuelo, Valencia, Spain. Methods: Twelve patients (24 eyes) with high myopic astigmatism (from 3.50 to 6.00 diopters) participated in the study. Astigmatic keratotomy was performed as the first step to reduce astigmatism; after 2 months, the residual refractive error was corrected with LASIK. Videokeratography measurements were conducted before and after each procedure. Topography maps were used to calculate the wavefront corneal aberrations for a 6.0 mm pupil diameter. Results: Total, coma-like, and spherical-like aberrations increased significantly from preoperatively to post LASIK (×6.34, ×2.52, and ×10.50, respectively; P<.01). Astigmatic keratotomy significantly increased coma-like (×4.04; P<.01) and spherical-like (×5.66; P<.01) aberrations. After LASIK, the coma-like aberration was significantly reduced (×0.62; P = .008) and the spherical-like aberration was significantly increased (×1.86; P<.01). Conclusion: Astigmatic keratotomy increased higher-order corneal aberrations, both coma-like and spherical-like, whereas LASIK performed after AK increased the spherical-like aberration and reduced the coma-like aberration.

Corneal topography changes after a 15 second pause in blinking

Purpose To examine the effect of a short pause in blinking on the quantitative topographic parameters of the corneal surface. Setting Refractive corneal surgery unit of a university eye hospital. Methods Using a TMS-1 instrument (Computed Anatomy, Inc.), corneal topographic parameters were measured 5 and 15 seconds after a complete blink in 12 healthy subjects. The main outcome measures were changes in the surface regularity index (SRI) and the surface asymmetry index (SAI). Results During the pause in blinking, the mean SRI value increased from 0.18 ± 0.19 (SD) to 0.30 ± 0.19 ( P < .02) and the SAI from 0.21 ± 0.08 to 0.24 ± 0.10 ( P = .079, not statistically significant). There were no significant changes in the values for potential visual acuity, corneal refractive power, or astigmatism. Conclusion The results indicated a significant change in corneal topography during even a short pause in blinking. In follow-up studies using corneal topography, all measurements should be done at a fixed time after a complete blink.