Laser In Situ Keratomileusis Surgery Research Articles

Traumatic flap dehiscence 15 years after LASIK: case report and review of the literature

Introduction: Corneal flap trauma rarely occurs years after laser in situ keratomileusis (LASIK), and management is not standardized. The authors report a case of LASIK flap dehiscence 15 years postoperatively with a review of the literature describing clinical characteristics, management, and outcomes of similar cases occurring at least 6 years postoperatively. Patient and Clinical Findings: A 55-year-old man with a history of LASIK surgery 15 years prior presented with flap dehiscence after trauma with a tree branch. His right eye uncorrected distance visual acuity (UDVA) at presentation was counting fingers. On slitlamp examination, the medial flap edge was folded underneath the temporal aspect. Diagnosis, Intervention, and Outcomes: The flap was unfolded, irrigated, repositioned, and instilled with topical antibiotics. The patient was started on prednisolone acetate 1% and moxifloxacin. On postoperative day 1, his UDVA improved to 20/50 and the flap remained centered and clear. His vision stabilized at 20/30 after 7 months. Peripheral epithelial ingrowth was noted without visual axis obscuration. Conclusions: This case, along with 20 reported instances of late traumatic flap dehiscence, highlights that early recognition with prompt intervention can optimize visual outcomes. Comparison of injury mechanisms, treatments, and complications may guide surgeons in patient counseling and care.

Surgical outcomes of laser in situ keratomileusis (LASIK) in patients with stable systemic disease

PurposeTo evaluate the surgical outcome in terms of safety, efficacy, predictability, and retreatment rate of LASIK surgery in patients with controlled systemic diseases in comparison with healthy individuals.MethodsThe retrospective study included data from 1936 eyes of 976 patients with stable systemic diseases who underwent LASIK surgery between January 2016 and June 2019. The safety, efficacy, predictability of the surgery, and retreatment rate were evaluated in comparison with a control group comprising 1951 patients. The study was approved by the local ethics committee and adhered to the principles of the Declaration of Helsinki. Statistical analysis was performed using R team and the level of statistical significance was set at p < 0.05.ResultsAll treatment groups demonstrated high safety and efficacy indices after LASIK surgery. Furthermore, the study arms demonstrated comparable predictability and retreatment rates to the control group in nearly all cases. Retreatment rates were significantly higher in the rheumatoid arthritis group (p = 0.03), while safety indices were significantly lower in the hay fever group compared to the control group (p = 0.004). No intra- or postoperative sight-threatening complications were documented.ConclusionOur findings suggest that selected patients with stable systemic conditions can safely undergo LASIK surgery and achieve comparable outcomes to healthy individuals. Further research is needed to better understand the treatment outcomes in this challenging patient population.

Recalcitrant Epithelial Ingrowth After LASIK: An Unexpected Complication

Introduction : Post-LASIK Epithelial Ingrowth (PLEI) is an uncommon complication of laser in situ keratomileusis (LASIK). Treatment for PLEI can be done surgically and medically, but recurrence is possible.&#x0D; Case Illustration : A 20-year-old female came with the appearance of white opacity on her right cornea, which has grown bigger in size over the last two months (Figure 1A and 1B). She had undergone three debridement surgeries prior to the visit due to the same complaint and history of LASIK surgery two years before. Visual acuity of the right eye showed 0.32 pinhole 0.63, epithelial ingrowth Probst/Machat grade III in 9 o’clock direction approximately 3mm x 3mm (Table 1), pooling on fluorescein test, intact flap, and punctate epithelial erosion (PEE). A surgery of flap reopening, epithelial debridement, corneal suture, and corneal crosslinking was conducted (Figure 2 and 3).&#x0D; Discussion : The incidence of PLEI, as reported by published studies, is relatively low. Hence, treatment in such cases is largely based on anecdotal case reports and small case series. Treatment of choice can be done according to clinical manifestation and severity of PLEI.&#x0D; Conclusion : A thorough and careful management of PLEI should be carried out to prevent its progress and recurrence.

Dry Eye Disease following LASIK, PRK, and LASEK: An Observational Cross-Sectional Study.

Dry eye disease is the most frequent non-refractive postoperative complication following refractive surgery. This prospective study investigated the development of dry eye disease after three common refractive laser surgeries: laser in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), and laser-assisted sub-epithelial keratectomy (LASEK). Patients who underwent uneventful refractive surgery in a single private medical center between May 2017 and September 2020 were included. Ocular surface disease was graded according to the Dry Eye Workshop severity (DEWS) classification. Patients were examined 6 months following refractive surgery. The analysis included 251 eyes of 137 patients: 64 eyes (36 patients) after LASEK, 90 eyes (48 patients) after PRK, and 97 eyes (53 patients) after LASIK. At 6 months post-surgery, the DEWS score was higher for the LASIK than the PRK and LASEK groups (p = 0.01). For the total cohort, severe DEWS score (grades 3 and 4) at 6 months post-surgery was correlated with female gender (p = 0.01) and to the amount of refractive correction (p < 0.001), but not to age (p = 0.87). In conclusion, LASIK surgery and female gender were associated with dry eye. Patients, particularly those with high myopia, should be counseled about the risk of developing dry eye after refractive surgeries.

Clinical Evaluation of Corneal Biomechanics following Laser Refractive Surgery in Myopic Eyes: A Review of the Literature.

The role of corneal biomechanics in laser vision correction (LVC) is currently being raised in the assessment of postoperative corneal ectasia risk. The aim of the paper was to evaluate the changes in corneal biomechanics after LVC procedures based on a systematic review of current studies. The results of a search of the literature in the PubMed, Science Direct, Google Scholar, and Web of Science databases were selected for final consideration according to the PRISMA 2020 flow diagram. Included in our review were 17 prospective clinical studies, with at least 6 months of follow-up time. Corneal biomechanical properties were assessed by Ocular Response Analyzer (ORA), or Corvis ST. The results of the study revealed the highest corneal biomechanics reduction after laser in situ keratomileusis (LASIK) followed by small incision lenticule extraction (SMILE) and surface procedures, such as photorefractive keratectomy (PRK) or laser-assisted sub-epithelial keratectomy (LASEK). In SMILE procedure treatment planning, the use of thicker caps preserves the corneal biomechanics. Similarly, reduction of flap thickness in LASIK surgery maintains the corneal biomechanical strength. Future prospective clinical trials with standardization of the study groups and surgical parameters are needed to confirm the results of the current review.

A Review of the Usage and Post-surgical Outcomes of Anesthesia for Laser In Situ Keratomileusis (LASIK) Procedure.

When laser in situ keratomileusis (LASIK) surgery is employed for myopia, hyperopia, and astigmatism, the process requires the usage of anesthetics to ensure that there is minimal patient harm and negative consequences once the procedure is complete. Statistical analysis was conducted as part of this review to evaluate the application of and distinctions between the different analgesics used for LASIK surgery by compiling and filtering information from multiple research studies. Topically administered oxybuprocaine and proparacaine were found to be the most commonly used anesthetics for LASIK, according to the data included in the review. It was also determined that there were no significant differences in terms of patient outcomes and drug concentrations when proparacaine was substituted for oxybuprocaine. This is particularly intriguing given their different chemical compositions. Temporary dry eyes were the most commonly reported adverse effect of LASIK when the anesthetic was employed. Perhaps cocaine derivatives produce similar anesthetic and post-surgical effects, but further investigations are needed to verify this hypothesis.

Accuracy of the Preoperative Predicted Percentage of Tissue Altered Calculation in Refractive Surgery Planning for Myopic LASIK.

To determine the reliability of the percentage of tissue altered (PTA) calculation as part of the planning strategy for myopic laser in situ keratomileusis (LASIK) by comparing the estimated PTA provided by preoperative calculation to the postoperative PTA actually achieved in microkeratome-assisted myopic LASIK. This retrospective study included 3,624 eyes of 3,624 patients who underwent mechanical microkeratome-assisted LASIK surgery for myopic correction. The calculated preoperative PTA values based on the planned flap thickness and ablation depth were compared with the actual achieved postoperative PTA using the difference of corneal central thickness postoperatively for assessing the achieved ablation depth and the intraoperative ultrasound-assisted flap thickness measurement. Regression analysis was performed to reveal preoperative parameters that might influence PTA calculation accuracy. The mean difference between the estimated and achieved PTA was 0.451 ± 3.45% (P < .001) (95% CI: 0.3708 to 0.5322) with a preoperative and postoperative mean PTA of 31.07 ± 4.07% and 31.52 ± 5.78%, respectively. The differences between the achieved and planned maximum ablation depth and flap thickness were 4.32 ± 13.70 µm (P < .001) and -1.61 ± 13.66 µm (P < .001), respectively. Although a statistically significant difference was found between the preoperative calculated PTA and actually achieved PTA, the difference in PTA value (less than 1%) was clinically non-significant and indicated a highly reliable metric for preoperative refractive surgery planning. [J Refract Surg. 2022;38(7):422-427.].

Efficacy and Safety of Surgically Managed Late Traumatic LASIK Flap Displacements in a Study of 66 Cases.

To evaluate safety and efficacy in the management of flap displacement after laser in situ keratomileusis (LASIK) and subsequent complications. This was a retrospective study performed using data recorded at the center's database from October 2002 to August 2021. Efficacy and safety were both converted to binary outcomes (loss of one or more lines and no change or gain in lines of visual acuity). The effects of time from surgery to complication and from complication to repair were assessed and the odds ratios and probabilities were calculated. The same procedure was applied to investigate the effect of these temporal variables on complications. A total of 66 eyes with late traumatic LASIK flap displacements were studied. Efficacy remained unchanged in 48 patients (64 eyes, 75%), and safety remained unchanged in 53 patients (59 eyes, 90%). Sixty-six patients (64 eyes, 100%) achieved visual acuity values of 20/40 and 45 patients (64 eyes, 70.3%) achieved values of 20/20. The flap displacement was resolved in the first 24 hours (SD ± 0.1 days). Surgery was performed in 58 patients (65 eyes, 90%). Epithelial ingrowth was the most frequent complication. Patients who underwent surgery tended not to lose lines (P = .05). The risk of developing epithelial ingrowth increases with time after LASIK surgery until traumatic flap displacement (odds ratio: 1.001; P < .001). The prevalence of dislocation during the study period was 0.012%. Visual safety values were favorable after resolution of the flap complication. Immediate surgical management leads to better visual efficacy, and the time between LASIK and trauma increases the risk of epithelial ingrowth after flap displacement. [J Refract Surg. 2022;38(4):270-276.].

Outcomes and Complications in Patients With Hypermobile Ehlers-Danlos Syndrome Who Have Undergone Laser In Situ Keratomileusis Surgery.

The purpose of this study was to determine the safety and outcomes of myopic laser in situ keratomileusis (LASIK) in patients who were secondarily diagnosed with hypermobile Ehlers-Danlos syndrome (EDS). We conducted a case series study on patients with hypermobile EDS who underwent myopic LASIK surgery. Visual acuity, manifest refraction, a full dilated eye examination, biometry measurements, and Scheimpflug imaging were performed in the Wilmer outpatient clinic. There were 24 eyes of 12 patients included in this study. All participants were White women with a mean age of 46.58 years (SD 8.91 years). Participants were seen at an average of 13.83 years (SD 4.3 years, range 6-21 years) after undergoing LASIK. None of the patients in the series had a diagnosis of hypermobile EDS before LASIK surgery. Overall, 92% of patients were happy they got LASIK. The uncorrected distance visual acuity was 20/20 or better in 68% of eyes, and the best-corrected visual acuity was 20/20 or better in 92% of eyes. Manifest refraction was within 1 diopter of plano in 79% of patients. Dry eye symptoms were present in 83% of patients, and 46% of eyes had either punctate epithelial erosions or decreased tear break-up time. One of the 12 patients developed corneal ectasia in both eyes. Patients with hypermobile EDS are generally satisfied with myopic LASIK correction, with good visual acuity outcomes and low rates of myopic regression. However, the risk of corneal ectasia may prevent laser vision correction from being a viable treatment option in these patients. Further studies are needed to make a definitive recommendation.

Myopic LASIK Outcomes: Comparison of Three Different Femtosecond Lasers and a Mechanical Microkeratome Using the Same Excimer Laser.

IntroductionTo compare the influence of one microkeratome and three femtosecond lasers on myopic laser in situ keratomileusis (LASIK) outcomes.MethodsRetrospective, observational cohort study. We compared 134 eyes treated with the IntraLase 60 kHz, 112 eyes treated with the Femto LDV Z6, 206 eyes treated with the FS200, and 98 eyes treated with the Hansatome zero compression microkeratome. All eyes were operated on using the same surgical protocol with the same excimer laser (Wavelight Allegretto) and were allocated to refraction-matched groups.ResultsOne day and one week postoperatively, uncorrected distance visual acuity was significantly lower in the FS200 group compared to others (P = 0.0001). This difference disappeared at the 1- and 3-month postoperative visits. Significant differences were found among groups in terms of safety index (P = 0.0001), residual sphere (P = 0.0001), and residual cylinder (P = 0.02) at the 3-month postoperative visit. No significant differences were found in corrected distance visual acuity or efficacy index.ConclusionAccording to our results, a slight delay in visual restoration after FS200 LASIK surgery might be expected. This delay was statistically significant at 1 day and 1 week postoperatively, but there were no differences from the 1-month visit onwards. Additionally, significant differences were found among devices in terms of safety index and the refractive results, which were found not to be clinically relevant.

Comparison of accommodation and accommodative micro-fluctuation after implantable collamer lens and LASIK surgery for myopia

BackgroundTo longitudinally analyze and compare the accommodative micro-fluctuation (MFs) and accommodative function between myopic patients after implantable collamer lens (ICL) implantation and laser in situ keratomileusis (LASIK).MethodsPatients with good corrected visual acuity (20/20 or better) and underwent ICL (V4c) and LASIK for myopic-correction (ranging from − 3.50 to − 8.50 D) were recruited. Refraction, amplitude of accommodation (AMP), accommodative lag, higher-order aberration (HOA), and MFs were recorded before surgery and 1 and 3 months after surgery. The ACOMEREF automatic refractor was used to measure the high-frequency component (HFC) of the MFs, which suggested tension of the ciliary muscle.ResultsThe study comprised 120 eyes. At 3 months after surgery, the manifest refractive spherical equivalent of the ICL and LASIK groups were − 0.11 and − 0.09 D, respectively (p = 0.46). HFC values were significantly higher at 1 month (p = 0.03) and 3 months postoperatively (p = 0.03) in the ICL group compared to that in the LASIK group. The ocular HOA of the ICL group was 1.08 ± 0.43 μm, which was lower than the LASIK group 1.45 ± 0.54 μm (p = 0.01). No significant differences in AMP and accommodative lag between groups were noted at 3 months postoperatively. There was a positive correlation between HFC and vault of the ICL lens (r2 = 0.14, p = 0.005). There were no correlations between HFC and ocular HOA and postoperative MRSE in the two groups (all p>0.05).ConclusionsThe HFC increased significantly after an early period of ICL implantation compared to laser in situ keratomileusis for myopic correction, which indicated increased tension of the ciliary muscle, and had a positive correlation on the vault of the ICL lens; However, studies with longer follow-up time and more structural evaluation are needed.

Clinical outcomes of epithelial ingrowth following laser in situ keratomileusis with mechanical debridement and compressed heating air flow: a case series.

To describe the clinical outcomes of manual scraping of epithelial ingrowth followed by compressed heating air flow after laser in situ keratomileusis (LASIK). We underwent a retrospective, noncomparative, and interventional case series. Twenty eyes of 17 patients were included in this study. Each patient with a history of LASIK underwent epithelial removal with mechanical debridement followed by compressed heating air flow. Our primary outcome was the recurrence of epithelial ingrowth after 3 months of follow-up, while our secondary outcomes were uncorrected distance visual acuity, corrected distance visual acuity, and complications after surgery. Ten patients (58.8%) were male, and eight eyes of seven (41.2%) patients underwent primary LASIK surgery, while12 eyes of 10 patients had flap-lift retreatment LASIK; sixteen eyes (80.0%) underwent mechanical microkeratome LASIK and four (20.0%) underwent femtosecond laser-assisted LASIK. Mean age at surgical removal of epithelial ingrowth was 37.0 years ± 9.3 years (range 24 to 55 years). There was recurrence of ingrowth in two eyes (10%) after 3 months of follow-up. The mean corrected distance visual acuity of patients before surgery was 0.07 ± 0.09 logMAR, and after the last follow-up was 0.02 ± 0.04 logMAR (p=0.06). The odds ratio of presenting with epithelial ingrowth after LASIK enhancement compared to primary LASIK was 29.41. Manual scraping followed by compressed heating air flow is a safe and effective treatment of clinically significant epithelial ingrowth after LASIK. At the last follow-up, no eye lost any line in corrected distance visual acuity.

Effect of photorefractive keratectomy versus laser in situ keratomileusis on corneal hysteresis in moderate myopic eyes

IntroductionAblation procedures used for vision correction such as photorefractive keratectomy (PRK) or laser in situ keratomileusis (LASIK) flap creation produce massive changes within the corneal structure and biomechanical properties. These changes are due to thinning of the central cornea and disruption of continuity of the collagen lamellae. Several approaches to assessment of the biomechanical properties have been proposed. Refractive photoablation procedures that decrease corneal hysteresis (CH) and corneal resistance factor (CRF) have been shown by several studies; therefore, here in our study we are going to discuss the effect of PRK versus LASIK on the corneal biomechanics and stability over time.AimTo compare the postoperative biomechanical properties of the cornea after PRK and after LASIK in eyes with moderate myopia.Patients and methodsThe study is 'prospective, controlled, and randomized.' In all, 40 eyes with moderate myopia (−2.0 to − 5.0 D) underwent refractive correction of myopia; 20 of them (group A) were enrolled for PRK while the other 20 of them (group B) were enrolled for LASIK surgery. CH and CRF were measured with an ocular response analyzer preoperatively and 1and 3 months postoperatively. All eyes were subjected to corneal topography preoperatively and 1 and 3 months postoperatively ocular response analyzer was used preoperatively and 1 and 3 months postoperatively.ResultsAll patients were followed up postoperatively at 1 and 3 months. The CH and CRF were measured in both groups preoperatively and postoperatively. In group A, the mean preoperative CH was 10.7 ± 0.4 (range: 10–11.1) and CRF was 10.2 ± 0.11 (range: 10.1–10.5), whereas in group B it was 10.57 ± 0.38 (range: 10–11.2) and the CRF was 10.21 ± 0.1 (range: 10–10.5), respectively, with no significant difference (P = 0.43 and 0.25, respectively).After 1 month, CH and CRF were 8.4 ± 0.27 (range: 7.9–9.1) and 8.2 ± 0.23 (range: 7.8–8.6) in group A and 8.3 ± 0.25 (range: 8.0–9.0) and 8.17 ± 0.19 (range: 7.9–8.5) in group B, respectively, with no significant difference (P = 0.28 and 0.45, respectively). At 3 months, CH and CRF were 8.6 ± 0.28 (range: 8.1–9.2) and 8.3 ± 0.21 (range: 7.8–8.6) in group A and 8.55 ± 0.26 (range: 8.2–9.1) and 8.28 ± 0.18 (range: 7.9–8.6) in group B, respectively, with no significant difference (P = 0.56 and 0.32, respectively). The corneal biomechanical parameters decreased after both PRK and LASIK procedures. The corneal biomechanical parameters decreased after both PRK and LASIK procedures. The postoperative measurements of CH and CRF at 3 months were lower than the preoperative values in both groups with a significant amount (P < 0.001).ConclusionBoth PRK and LASIK substantially weaken the biomechanical strength of the cornea, the greater the amount of myopic correction, the more the change in corneal biomechanics.

Late onset of microbial keratitis after laser in situ keratomileusis surgery: case series.

To report predisposing factors, clinical features, microbiology spectrum, antibiotic resistance, antimicrobial therapy, and outcomes of patients with a previous laser in situ keratomileusis (LASIK) surgery and diagnosed with presumed microbial keratitis. Sydney Eye Hospital, Sydney, New South Wales, Australia. Retrospective case review. Patients were identified from pathology and hospital coding data from 2012 to 2016. Inclusion criteria were all patients with a previous LASIK surgery, a presumed diagnosis of microbial keratitis, and a corneal scrape performed and aged older than 18 years. Demographics, clinical details, and outcomes were collated from the medical records. Sixteen patients were included, with median age of 41.5 years (range 22 to 85 years) and 56.2% of women. The median time between LASIK procedure and microbial keratitis presentation was 38.3 months (interquartile range 6.7 to 77.45 months). Cultures were positive for bacteria in 12 (75%) of 16 scrapes. Of the bacterial isolates, 12 (85.7%) were gram-positive and 2 (14.3%) gram-negative. Sensitivity profiles for the isolated bacteria were similar between fortified antibiotics (cefalotin and gentamicin) and commercial products (chloramphenicol and ofloxacin). Complications included the need for tectonic grafts, nonhealing epithelial defects, thinning, and neovascularization. Late onset of keratitis after LASIK can occur with no positive cultures for nontuberculous mycobacteria, no interface involvement, and no other usual features reported in case series of infectious keratitis in LASIK patients. It has a similar clinical course to non-LASIK keratitis, such that the surgery may not have been a risk factor for infection.

Effect of suction on the posterior segment after LASIK using Femtosecond Laser vs Microkeratome

Background: Creating a successful corneal flap is the first critical step during LASIK surgery. Two techniques are used to produce corneal flaps during LASIK surgery: a microkeratome or a femtosecond laser. Femtosecond laser has a significant impact on refractive surgery by enabling non-mechanical creation of corneal flaps during laser in situ keratomileusis (LASIK). During LASIK flap creation, intraocular pressure (IOP) increases to levels exceeding 65 mm Hg. Femtosecond laser flap creation exerts less extreme IOP fluctuations but requires more procedural time than when a microkeratome is used. This study was conducted upon 60 eyes of 38 patients to evaluate the effect of applied suction during LASIK procedures on the posterior segment of myopic eyes, whether the flap was created by Microkeratome or Femtosecond laser. The study subjects were equally divided into 2 groups: group F (30 eyes of 20 patients) underwent femtosecond laser-assisted LASIK surgery and group M (30 eyes of 18 patients) underwent microkeratome-assisted LASIK surgery using Moria M2 for the treatment of myopia. It was found that the central macular thickness and RNFL thickness were not changed significantly in both groups when measured 1 week after surgery. Regarding the incidence of PVD, there was a higher incidence in group F, it was detected in 8 eyes (26.7%) compared to group M, it was detected in 1 eye (3.3%). Conclusion: Slight localized changes of macular thickness and reduction of the RNFL thickness were caused by LASIK using the two major forms of flap creation, namely a microkeratome or a femtosecond laser. Regarding the incidence of PVD, it was found that femtosecond laser-assisted LASIK using Visumax femtosecond laser had a higher incidence than that after microkeratome-assisted LASIK with the Moria M2. So the surgery of LASIK is safe and efficient, but surgeons should choose effective and safe suction mode, shorten the suction time and exclude potential retinopathy and pre-existing glaucoma before surgery to improve the safety and efficacy of LASIK.

Evolution of corneal epithelial remodeling after myopic laser in situ keratomileusis surgery measured by anterior segment optical coherence tomography combined with Placido disk.

Purpose:To investigate patterns of short- and long-term variations in corneal epithelial thickness (CET) after myopic laser in situ keratomileusis (LASIK) using anterior segment optical coherence tomography (AS-OCT) combined with Placido disk-based topography.Methods:In this retrospective study, 36 subjects (72 eyes) who underwent LASIK myopic surgery and 53 healthy subjects (106 eyes) who served as controls were enrolled. AS-OCT (MS-39) was performed in all patients before, 1 day, 1 month, and 6 months after surgery. Statistical analysis was performed to analyze CET changes over time after LASIK and to detect patterns of definitive CET remodeling compared to healthy subjects. Multivariate analysis was performed to look for possible predictors of final CET.Results:There was no statistically significant difference between groups in terms of demographic and anterior segment parameters (all P > 0.05). After LASIK, all sectors and rings got thicker over time (1.62–8.32 μm; P < 0.01). Except for the central sector, all areas achieved the thickest CET value one day after surgery with a progressive epithelial thinning between 1 and 6 months of follow-up. Changes on CET occurred independently of the grade of myopia before LASIK or final refraction (P > 0.05). None of the clinical variables studied, including diopters corrected, were found to be correlated with final CET (P > 0.05).Conclusion:Independent of anterior segment parameters and diopters corrected, CET becomes thicker after LASIK surgery. Central and inner ring sectors thicken more than those more peripheral. CET remodeling after myopic LASIK should be taken into consideration when planning refractive surgery.

Elliptical versus circular flap configuration in myopic eyes undergoing femtosecond laser in situ keratomileusis surgery: A contralateral eye study.

Purpose:To study whether a customized elliptical flap configuration offers any visual, refractive, or biomechanical advantage over the “conventional” circular flaps in patients undergoing myopic laser in situ keratomileusis (LASIK).Methods:A prospective interventional contralateral eye study was undertaken enrolling 290 eyes of 145 myopic patients (≤−6.0D) undergoing LASIK, wherein the corneal flap was created in one eye using a customized elliptical flap configuration versus a conventional circular flap configuration in the other eye. Postoperatively, we compared the visual outcome, change in higher-order aberrations, corneal asphericity, and corneal biomechanics.Results:The visual outcomes, including higher-order aberrations, were comparable between the two groups. Changes in spherical aberration (mean: 0.234–0.331 versus 0.234–0.42; P = 0.644), corneal asphericity (−0.32–0.34 versus − 0.34–0.45; P = 0.42), corneal hysteresis (9.35–7.33 versus 9.4–6.71, P = 0.489), corneal resistance factor (9.71–7.40 versus 10.38–6.9, P = 0.181) were comparable between the elliptical and circular groups, respectively.Conclusion:We evaluated the usefulness of a customized elliptical flap configuration for performing LASIK surgery. Our data suggests that elliptical flaps may be associated with superior visual and biomechanical performance compared to circular flaps. This is certainly relevant in eyes with “borderline” pre-LASIK profile to improve patient satisfaction and safety after surgery.

EFFECT OF SUCTION USING MORIA MICROKERATOME ON MACULAR AND RETINAL NERVE FIBER LAYER THICKNESS DURING LASIK USING OPTICAL COHERENCE TOMOGRAPHY

Background: Laser in situ keratomileusis (LASIK) combines keratomileusis with the accuracy of the excimer laser and is used worldwide for correction of a broad range of refractive abnormalities. Objective: To asses structural and functional changes of macular and NFL using spectral domain optical coherence tomography (SD-OCT) following LASIK surgery using moria microkeratome. Patients and Methods: A total of 50 were enrolled in our study to be examined before and one month after operation using OCT device Al-Azhar University Hospital (Damietta). A complete ophthalmological examination included uncorrected visual acuity; best corrected visual acuity, full slit lamp examination and corrected tonometery. Examination was done by optical coherence tomography to record macular and NFL thickness. Results: There was no effect on the thickness of the project before the operation (13.66 ± 18.99) and after the operation (13.31 ± 18.87). The results also showed that there was no effect on the thickness of the nerve fibers before the operation (5.31 ± 40.18) and after the operation (5.33 ± 39.90). Conclusion: LASIK is a safe procedure on posterior segment of the eye, Suction with no effect on macular and retinal nerve fiber layers thickness.

Two-year successful results of femto-LASIK in steep and opacified corneas

&#x0D; Background: Flap creation is the most critical step of laser in situ keratomileusis (LASIK). The introduction of the femtosecond laser with its uniform flaps, which enhance the accuracy of LASIK, has decreased the risk of flap-related complications like buttonholes and incomplete flaps. We recommended femtosecond laser-assisted LASIK (FS-LASIK) in the presence of superficial corneal opacities.&#x0D; Case Presentation: We report a case of a 31-year-old female who reported to the Cornea clinic of the Sohag Center for LASIK and Corneal Surgeries, Sohag, Egypt, complaining of bilateral decreased vision due to refractive error. The uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) were 0.01 and 0.7 with a refractive correction of -3.50Ds/ –3.00Dc x 172° in the right eye and 0.01 and 0.6 with a refractive correction of -1.75 Ds/-6.00Dc x164° in the left eye, respectively. Slit-lamp examination of the anterior segment showed bilateral superior vascularized corneal scars and a linear superior conjunctival scar suggestive of old trachoma. Corneal tomographic imaging with a Scheimpflug based tomography device (Oculus Inc., Wetzlar, Germany) revealed a symmetrical bow tie with a very steep cornea without other ectatic changes. The patient underwent bilateral FS-LASIK with an excimer laser. No intraoperative complications occurred. She was followed up for two years with serial corneal topographies and stable post-LASIK results and visual outcomes.&#x0D; Conclusions: FS-LASIK, in the presence of superficial corneal opacities, was safe and effective and induced no complications with special precautions. However, these findings are yet to be confirmed using well‐designed clinical studies with larger samples and longer follow-ups.

Role of central corneal thickness in intraocular pressure changes after corneal refractive surgery

Objective The aim of the study was to assess importance of central corneal thickness (CCT) in the intraocular pressure (IOP) variation after corneal refractive surgery. Patients and methods This prospective, interventional study contains 75 patients who were divided into three equal groups. Group I had undergone femtosecond laser-assisted in-situ keratomileusis (femto-LASIK); Group II had undergone laser in-situ keratomileusis (LASIK); and group III had undergone photorefractive keratectomy (PRK). The evaluated parameters included age, sex, spherical equivalent refraction (preoperative and postoperative), CCT preoperatively and postoperatively and IOP preoperatively and postoperatively at 1, 3, and 6 months by Goldmann applanation tonometry (GAT) and ocular response analyzer. Result The mean CCT reductions were 56.6 ± 34.1, 52.8 ± 25.5, and 40.5 ± 25.9 μm after femto-LASIK, LASIK, and PRK surgery. The mean IOP reductions by GAT were 2.42 ± 1.9, 2.46 ± 2.56, and 1.14 ± 1.31 mmHg after 1 month in femto-LASIK, LASIK, and PRK; however, after 3 months 3.14 ± 1.87, 3.22 ± 2.99, and 2.7 ± 2.23 mmHg after femto-LASIK, LASIK, and PRK. After 6 months the mean IOP reduction was 3.22 ± 1.83, 3.44 ± 2.91, and 2.84 ± 2.32 mmHg after femto-LASIK, LASIK, and PRK. The mean IOPg reduction was 2.53 ± 1.81, 3.19 ± 1.76, and 3.29 ± 1.87 mmHg at 1, 3, and 6 months after femto-LASIK. However, the mean decrease in IOPg was 2.67 ± 2.08, 3.28 ± 1.95, and3.52 ± 1.89 mmHg at 1, 3, and 6 months after LASIK. The mean decrease in IOPg was 1.26 ± 1.98, 2.85 ± 1.98, and 2.98 ± 1.79 mmHg at 1, 3, and 6 months after PRK. IOPcc is not correlated with CCT. Conclusion The IOP by GAT and IOPg reduction after corneal refractive surgery significantly depends on CCT changes, but IOPcc measurements are not associated with CCT.