Predictability of the Achieved Lenticule Thickness in Keratorefractive Lenticule Extraction for Myopia Correction.

PURPOSE: To assess the predictability between the SCHWIND ATOS femtosecond laser (SCHWIND eye-tech-solutions) read-out and achieved lenticule thickness measured using MS-39 anterior segment optical coherence tomography (ASOCT; CSO) at the corneal vertex at postoperative 1 day and 1 and 3 months of follow-up. METHODS: This retrospective case series included 130 eyes of 65 consecutive patients who were treated with SmartSight (SCHWIND eye-tech-solutions) lenticule extraction. Sixty-four percent of patients were women with a mean spherical refraction of -4.98 ± 1.19 diopters (D) and mean astigmatism of 0.53 ± 0.64 D. The measurements were performed using AS-OCT with the Phoenix Software v 4.1.1.5. Lenticule thickness was obtained by the subtraction method between preoperative and postoperative total corneal thickness. RESULTS: A lower reduction in central corneal thickness (CCT) compared to the laser read-out for all three follow-up visits can be observed. Essentially, the reduction in CCT was identical at 3 months versus 1 month. The reduction in CCT was lowest at postoperative 1 day. Examining the 1- and 3-month data (essentially equivalent), one can see a best fit of y = 0.94 x -7 µm. CONCLUSIONS: The reduction in CCT was stable from 1 month of follow-up. The stable reduction in CCT was -6% (-1.5% after accounting for design decisions) and -7 µm lower than the respective laser read-out. The findings are predictable, showing a certain level of the lenticules becoming slightly thinner than their respective laser read-outs. [J Refract Surg. 2023;39(11):728-735.].

Management of Post-LASIK Ectasia.

Background: Corneal ectasia is a sight-threatening complication of corneal refractive surgery characterized by progressive steepening and thinning of the cornea and subsequent loss of best-corrected visual acuity. Objective: To report the clinical outcomes following treatment of post-laser in situ keratomileusis (LASIK) induced ectasia. Methods: This is a retrospective case series of 7 patients (10 eyes) which developed post-LASIK ectasia. In these cases of postoperative ectasia, the presented clinical signs were either forme fruste keratoconus, thin cornea, posterior elevation map value > +15.0µm, or residual stromal bed < 300µm. All cases were treated with either collagen crosslinking (CXL) alone or combined with PRK or CXL and phakic intraocular implant using the Dresden protocol and a slight modification thereof. In all cases, the flap was created using the Moria M2 mechanical microkeratome (average flap thickness 118.15±12.88µm), and refractive error was corrected using the Wavelight Allegretto excimer laser. Results: Average preoperative corrected visual acuity (CDVA) was 0.75 (±0.26) Snellen. Postoperative CDVA significantly increased to 0.86 (±0.13) Snellen (p=0.04, paired t-test). One eye lost three lines of its baseline CDVA (before ectasia), while all other eyes regained lines of CDVA. All cases remained stable during the follow-up. Conclusion: Several surgical procedures are used for the management of corneal ectasia. However, the best surgical approach should be determined based on the state of progression of the disease. Although ectasia remains a potentially devastating complication after refractive surgery, most patients can regain functional visual acuity with appropriate management, and corneal transplantation is infrequently indicated.

Stereoacuity and Multifocal Intraocular Lenses - a Systematic Review.

Background: Among various visual functions, stereoacuity, or the ability to perceive depth, is the most sophisticated binocular function. Many publications discuss the influence of retinal image formation by multifocal intraocular lenses on glare and contrast sensitivity, but only a few present results of testing binocular vision in patients with multifocal intraocular lenses. Objective: This article is designed to review the results of testing binocular vision in patients with multifocal intraocular lenses implanted in cataract surgery. Methods: This article was performed based on a literature review and Internet search through scientific databases such as PubMed, Scopus, Web of Science, and Google Scholar. Results: Some reports found that patients implanted with the monofocal lens, when measured with a near addition, presented statistically significant better stereoacuity scores than those implanted with any of the multifocal intraocular lens types. When the TNO test was used for measurement, statistically significant better stereoacuity was disclosed with the refractive multifocal intraocular lens than with the diffractive-based multifocal intraocular lens design. Stereoacuity scores, even within the same types of lenses, were significantly better with the Titmus test than with the TNO test. Conclusion: Stereoacuity is not affected by multifocality-induced retinal blur as it is by other causes of image degradation such as small residual refractive error very early opacification of ocular media or dry eye. Multifocal intraocular lenses do not cause more functional aniseikonia than would be expected with a monofocal intraocular lens. Since stereoacuity is compromised with unilateral multifocal intraocular lens implantation bilateral implantation should be attempted.

Prevalence of keratoconus in refractive surgery practice population in North Macedonia.

PURPOSE: To determine the prevalence of keratoconus (KC) in relation to ethnicity in a group of people who consulted an ophthalmological care institution seeking for refractive surgery in N. Macedonia. METHODS: This was a cross-sectional, interventional retrospective study. Chart reviews were performed for all new patients attending between January 2016 and January 2020 at the Sistina Ophthalmology Hospital in Skopje. All patients were screened; KC diagnosis and classification were based on the corneal topography. Ethnicity and gender classifications were according to patients' self-opinions. RESULTS: A total of 2812 patients charts reviewed. The mean age was 31.71 years (SD ± 9.73), and 1209 (43%) were male. A total of 2050 (72.9%) declared themselves as Macedonians, 649 (23.1%) Albanians, 76 (2.7%) Turks and 37 (1.3%) in other ethnicities. Differences in age between the ethnic groups were statistically significant (x2 = 90.225, p < 0.001). KC was diagnosed in 343 patients (12.2%), while 9 (0.7%) were KC suspects and 6(0.21%) presented pellucid marginal degeneration. KC was more frequent in males (n = 246, 71.7% of total) and skewed toward younger patients. Increasing patients' age decreased the odds of KC diagnosis by 3.7% (95% CI 1.8%-4.4%) per annum. Males were four times more likely to be diagnosed with KC (AOR = 4.01; 95% CI 3.12-5.16). In comparison with Macedonian patients, Turks were more likely to be diagnosed with KC (AOR = 4.09; 95% CI 2.47-6.78). There was no difference between Macedonians and Albanians (p = 0.08). CONCLUSION: The prevalence of KC at a refractive surgery practice in N. Macedonia is much higher compared with general population (6.8/100,000) and similar to the prevalence in Middle East Asia. Nationwide screening programs are needed to diagnose the disease earlier.

Comparison of Flap Characteristics Created with Two Different Methods in Laser in Situ Keratomileusis (LASIK).

BACKGROUND: The creation of corneal flap is considered to be the most critical part of laser in situ keratomileusis (LASIK) surgery. Currently, flaps can be created with mechanical micorkeratomes or femtosecond lasers. OBJECTIVE: To analyze and compare flap characteristics created with two different methods for flap creation in Laser in situ keratomileusis (LASIK). METHODS: This was a retrospective study. The thickness and morphology of the flap were compared between the two mechanical microkeratomes (group I - Moria M2, group II - Moria SBK One Use Plus) and femtosecond laser (group III - Ziemer Femto LDV). Central flap thickness was measured intraoperatively, while the flap profile was measured with anterior optical coherence tomography at two axes (90° and 180°) and 5 measuring points on the first day, the first week, and one month after the surgery. RESULTS: Central flap thickness was 110.91±15.79 micrometers (µm) (80-164 µm) in group I, 98.08±13.33 µm (65-136 µm) in group II and 103.52±13.89 µm (66-138 µm) in group III. Anterior optical coherence tomography revealed a meniscus-shaped flap in all three groups at both axes (90° and 180°). The least variability in flap thickness was observed in group III (±6 µm). CONCLUSION: All three methods of flap creation provide good shape and thickness reproducibility. Ziemer Femto LDV femtosecond laser had the least variable flap thickness in a single flap. Mechanical microkeratomes had slightly lower performance.

Clinical Outcomes With a New Continuous Range of Vision Presbyopia-Correcting Intraocular Lens.

PURPOSE: To evaluate the clinical outcomes including patient-reported outcome measures in a sample of eyes undergoing bilateral cataract surgery with implantation of a new model of presbyopia-correcting intraocular lens (IOL). METHODS: This non-randomized prospective case series enrolled 206 eyes of 103 patients undergoing phacoemulsification cataract surgery with bilateral implantation of the TECNIS Synergy IOL (Johnson & Johnson Vision). High and low contrast visual acuity, refractive, defocus curve, and patient-reported visual performance (Catquest-9SF questionnaire) outcomes were evaluated during a 3-month follow-up. RESULTS: A total of 96.1% (99 of 103) and 91.3% (94 of 103) of patients achieved binocular postoperative uncorrected distance (UDVA) and near visual acuity (UNVA) of 0.00 logMAR (20/20), respectively. Mean postoperative mesopic UNVA for both eyes was 0.14 ± 0.03 logMAR. Likewise, mean binocular UDVA and UNVA were 0.00 ± 0.03 and 0.04 ± 0.02 logMAR. An almost flat mean defocus curve was obtained, with visual acuities between 0.00 and 0.10 logMAR for most defocus levels in both eyes. A reduction of contrast led to a limited but statistically significant change in UNVA in both eyes (P < .001). The Rasch calibrated scoring of item 2 and the Rasch calibrated mean score of the Catquest-9SF questionnaire increased significantly with surgery (P < .001). CONCLUSIONS: This new presbyopia-correcting IOL provides a continuous range of functional focus, with a limited deterioration under mesopic conditions, which is perceived as a satisfactory outcome by the patient if proper patient selection is performed. [J Refract Surg. 2021;37(4):256-262.].

Are changes in visual acuity and astigmatism after corneal cross-linking (CXL) in keratoconus predictable?

PURPOSE: To evaluate changes in corrected distance visual acuity (CDVA), ratio of anterior and posterior corneal radii over the thinnest region of the cornea (ARC/PRC), and astigmatism after cross-linking (CXL) in keratoconus. METHODS: Subjective refraction and ARC/PRC (using Pentacam™) were monitored over 1 year in (I) keratoconus treated with routine CXL (n = 53), (II) relatively stable keratoconus (n = 23), and (III) age/gender matched controls (n = 24). RESULTS: CDVA (median, mode, interquartile range) improved significantly in group I, compared with groups II and III (p < 0.05), from 0.45 (0.60, 0.20-0.63) to 0.80 (0.95, 0.60-0.95); change in CDVA was associated with preop CDVA (p < 0.01 at all times postop). ARC/PRC (mean ± sd, 95% CI) changed from 1.362 (± 0.048, 1.347-1.377) to 1.425 (± 0.073, 1.401-1.449). CDVA and ARC/PRC remained stable in II and III. Significant relationships were revealed between logCDVA and ARC/PRC in I and II (at 12 months, I rs = - 0.464, II rs - 0.449) and logCDVA at postop(y), log CDVA at preop(x1), and ARC/PRC at preop(x2) in I (at 12 months, y = 0.356x1 - 1.312x2 + 1.806, r21 = 0.494, r22 = 0.203). Astigmatic power (mean ± sd, 95% CI) improved from - 3.10DC (± 1.52, - 3.55 to - 2.66) to - 2.53DC (± 1.24, - 2.90 to - 2.17) in I, and worsened from - 1.27DC (± 1.32, - 1.81 to - 0.73) to - 1.61DC (± 1.28, - 2.13 to - 1.09) in II. Vector analysis revealed in group I (a) the power of the surgically induced astigmatism (SIA) was linked to astigmatic power at preop and (b) the difference between the axis of astigmatism at preop(ø) and the axis of the SIA was linked to ø. CONCLUSION: CXL improved CDVA, increased the ARC/PRC ratio, and modified the association between CDVA and ARC/PRC. The change in CDVA was linked to preop CDVA and ARC/PRC values. The association between SIA and preop astigmatism implies there is not a simple cause and effect relationship with CXL.

The relationship between patient age and residual refractive error after uneventful laser in situ keratomileusis for moderate-to-high hyperopia.

PURPOSE: To determine if the manifest sphero-cylindrical residual refractive error, at various time points over a 12-month postop period after laser in situ keratomileusis (LASIK) was associated with patient age at time of surgery. METHODS: Patients with moderate to high hyperopia (3.00-7.00 DS) and astigmatism ⩽2 DC underwent LASIK using Wavelight Allegretto Eye Q (400 Hz). Treatments were centered on corneal vertex, flaps were made with Moria M2 mechanical microkeratome. Pre-and postoperative uncorrected and corrected distant visual acuity, best corrected spherical equivalent (SEQ) were measured. Measurements were taken at 1 week, 1, 3, 6, and 12 months after the surgery. Target refraction was emmetropia. Total of 161 patients were treated. In binocular cases, data from the right eyes were included for analysis. In this article, we report on refraction data only. Raw data were subjected to several permutations to elicit any links between refractive outcomes and patient age. RESULTS: The key findings were as follows y = postop SEQ (diopters), x = patient age (years), ln(x) = natural logarithm of patient age: At 1 month, y = x[0.049 -0.011.ln(x)] (R = -0.205, p = 0.001, n = 161). At 3 months, y = x[0.077 -0.017.ln(x)] (R = -0.355, p < 0.001, n = 161). At 6 months, y = x[0.088 -0.020.ln(x)] (R = -0.382, p < 0.001, n = 161). At 12 months, y = x[0.093 -0.021.ln(x)] (R = -0.409, p < 0.001, n = 161). There was no significant association between x and y at 1 week (p > 0.05). CONCLUSION: Residual postop refractive error after LASIK for hyperopia has a logarithmic association with patient age at time of surgery. In younger patients there is tendency toward undercorrection, the opposite occurs in older patients and this persists 1 year after treatment.

Changes in the Higher Order Ocular Aberrations and Central Corneal Thickness After T-PRK and Fs-LASIK.

INTRODUCTION: Refractive surgery procedures, transepithelial photorefractive keratectomy (T-PRK), and femtosecond laser in situ keratomileusis (Fs-LASIK) are regarded as safe and efficacious methods for correcting myopia and myopic astigmatism. These two methods do not have many differences in results when treating spherical myopia while differences exist in the treatment of astigmatism correction. Vector analysis presents a powerful tool to show the real differences between these two methods regarding high ocular aberrations and central corneal thickness of treated eyes. AIM: The aim of the study is to investigate changes in higher order ocular aberrations (HOAs) and central corneal thickness (CCT) following treatment of myopia and myopic astigmatism above -5.00DS and up to -2.00DC after either T-PRK or Fs-LASIK. METHODS: Patients (30 eyes per group) underwent T-PRK (group I) or Fs-LASIK (group II) procedure using the Schwind Amaris 750S laser. HOAs (3mm&5mm pupil) and CCT were measured objectively at pre-, 1,3 & 6 months postop in each case. RESULTS: Key results at 6 months were: i) mean values of trefoil (5mm pupil) were 0.092µm (sd,0.055,95% CI 0.072 to 0.112) & 0.126µm (sd,0.078,95% CI 0.098 to 0.154) in group I, and 0.088µm (sd,0.058,95% CI 0.067 to 0.109) & 0.064µm (sd,0.034,95% CI 0.052 to 0.076) in group II (P=0.001 at 6 months); ii) Changes in CTT (ΔCTT) and best spherical equivalent correction (ΔBSE) was significant in group II (ΔCCT=-26.55[ΔBSE]-14.06,R=0.486,P=0.006) but not in group I (p=0.034). CONCLUSIONS: After T-PRK trefoil is worse than Fs-LASIK. The predictability of corneal changes is better following Fs-LASIK.

Keratoconus Progression Classification One Year After Performed Crosslinking Method Based on ABCD Keratoconus Grading System.

INTRODUCTION: Keratoconus is described as a degenerative bilateral, progressive, noninflammatory corneal disorder characterized by ectasia, thinning, and increased curvature. Keratoconus progression classification 1 year after performed crosslinking method in this study is based on the ABCD keratoconus grading system. AIM: To evaluate the possible keratoconus progression one year after performed a crosslinking (CXL) method based on the ABCD keratoconus grading system. Methods: Seventeen keratoconus patients (22 eyes) were included in this prospective study. CXL procedure was performed using the standard Dresden protocol at Eye Clinic Svjetlost Sarajevo with the inclusion period from January 2017 to January 2018. Twelve patients had monocular, and 5 patients had binocular treatments with follow up of 12 months. Preoperative and postoperative stages were compared using the ABCD keratoconus grading system measured on rotating Scheimpflug corneal tomography-based machine - Pentacam (Pentacam HR, Oculus Optikgeräte GmbH, Wetzlar, Germany). RESULTS: Out of 22 eyes, one eye had keratoconus stage I-II, 6 eyes had stage II, 4 eyes had stage III, and 9 eyes had stage III-IV. There was no statistically significant gradient change of keratoconus in comparison to one month after the surgery, p>0.05. There was no progression of the gradient when comparing to the preoperative stage. CONCLUSIONS: Corneal cross-linking could effectively stabilize the progression of keratoconus, as assessed by key corneal topographic parameters. Analyzing the trend of stage change in 12 months follow up after the crosslinking procedure of keratoconus patients there was no progression of a gradient in comparison to the preoperative stage. According to our results, we can conclude that CXL is a safe and effective procedure in treating keratoconus.

Vector Analysis of Changes in the Higher Order Ocular Aberrations and Central Corneal Thickness After T-PRK and Fs-LASIK.

INTRODUCTION: Refractive surgery procedures, transepithelial photorefractive keratectomy (T-PRK) and femtosecond laser in situ keratomileusis (Fs-LASIK) are regarded as safe and efficacious methods for correcting myopia and myopic astigmatism. These two methods do not have much differences in results when treating spherical myopia, while some differences does exist in treatment of myopic astigmatism. Vector analysis presents powerful tool to show the real differences between these two methods regarding higher order ocular aberrations and central corneal thickness of treated eyes. AIM: The aim of the study is to investigate changes in higher order ocular aberrations (HOAs) and central corneal thickness (CCT) following treatment of myopia and myopic astigmatism above -5.00DS and up to -2.00DC after either T-PRK or Fs-LASIK. METHODS: Patients (30 eyes per group) underwent T-PRK (group I) or Fs-LASIK (group II) procedure using Schwind Amaris 750S laser. HOAs (3mm&5mm pupil) and CCT were measured objectively at pre-, 1,3 & 6 months postop in each case. RESULTS: Key results at 6 months were: i) mean values of trefoil (5mm pupil) were 0.092µm (sd,0.055,95% CI 0.072 to 0.112) & 0.126µm (sd,0.078,95% CI 0.098 to 0.154) in group I, and 0.088µm (sd,0.058,95% CI 0.067 to 0.109) & 0.064µm (sd,0.034,95% CI 0.052 to 0.076) in group II (P=0.001 at 6 months); ii) Changes in CCT (ΔCCT) and best spherical equivalent correction (ΔBSE) was significant in group II (ΔCCT=-26.55[ΔBSE]-14.06,R=0.486,P=0.006) but not in group I (p=0.034). CONCLUSIONS: After T-PRK trefoil is worse than Fs-LASIK. The predictability of corneal changes is better following Fs-LASIK. .

The relationship between clinical measures of aniseikonia and stereoacuity before and after LASIK.

PURPOSE: To determine the significance of changes and and inter-relationships between three markers of binocular function (aniseikonia, distance and near stereoacuity) following unremarkable LASIK at 3 and 6 months postoperatively. METHODS: All patients underwent LASIK using the Schwind Amaris 750S and the flaps were created using Intralase 150 kHz. Patients were I, monocular myopes II, binocular myopes III, binocular hyperopes IV, binocular astigmats V, anisometropes and VI, matched age and gender control (n = 20 in each group except III where n = 18). Aniseikonia (Awaya test), distance and near stereoacuity (Randot tests) were measured before surgery, and at 3 and 6 months after surgery. At all times data were collected under constant conditions and analyzed using appropriate non-parametric statistical tests. RESULTS: The following statistically significant changes were found after applying the Bonferroni correction (p ≤ 0.001); aniseikonia reduced (groups I, III, IV, V), stereoacuity improved at distance (groups I, III-V) and near (groups I, V). Inter-group differences in aniseikonia distance and near stereoacuity were significant preoperatively, but not postoperatively. In groups I, IV and V, the changes in aniseikonia and stereoacuity (near and distance) were significantly correlated with the preoperative value. Aniseikonia was significantly correlated with distance and near stereoacuity preoperatively but not postoperatively. CONCLUSION: Binocular function improved in all groups after LASIK except in binocular myopes. In general, binocular function was still low compared with the control group at six months postoperatively. It is unclear why binocular function improved in the binocular astigmats.

Cross-linking treatment for better visual acuity.

Aim To correlate the maximum anterior sagittal curvature (Kmax) changes and uncorrected (UDVA) and corrected distance visual acuity (CDVA) in keratoconus patients after the cross-linking (CXL) procedure. Methods Forty-four eyes of 34 patients with keratoconus were analysed after the standard Dresden protocol CXL procedure had been performed. All patients underwent complete preoperative examination with a follow-up of 12 months with focus on UDVA, CDVA and Oculus Pentacam (Scheimpflug technology) analysis. We analysed and correlated Kmax changes in the postoperative period of 12 months together with visual acuity changes. Results Visual acuity improved significantly in the first 3 months after the procedure and even more significantly until the end of the first year. Even Kmax is the most relevant and most followed parameter for progression and regression of keratoconus, its lowering was not directly correlated with the visual acuity improvement (both uncorrected and corrected) in the first 6 months after corneal CXL procedure. Kmax was changed significantly in the period of 12 months post cross linking, but not in the first 6 months. Conclusion Corneal CXL should be considered as a procedure not just for corneal stiffening and stabilization, but also for visual acuity improvement in keratoconus patients.

Treatment of High Astigmatism with WaveLight Allegretto Eye-Q Excimer Laser Platform.

INTRODUCTION: The WaveLight Allegretto Eye-Q is a flying-spot excimer laser, with a pulse repetition rate of 400Hz, with two galvanometric scanners for positioning laser pulses. The system has an infrared high speed camera operating at 400Hz to track the patient's eye movements that either compensates for changes in eye position or interrupts the treatment if the eye moves outside a preset predetermined range. AIM: The purpose of this study was to investigate WaveLight Allegretto Eye-Q 400Hz laser delivery platform aimed to correct astigmatism by subjecting the pre and postoperative astigmatic values to vector analysis. METHODS: Patients were divided into two groups, depending on the type of astigmatism. Astigmatism was between 2 and 7 diopters (D). A total of 188 eyes (110 patients), 127 eyes (71 patients) with myopic astigmatism and 61 eyes (39 patients) with mixed astigmatism underwent unremarkable LASIK correction on WaveLight Allegretto Eye-Q 400Hz. The preoperative and postoperative sphere, negative cylinder [C] and axis (ø) of manifest refractions were subjected to vector analysis by calculations of the standard J0 (cos [4π(ø-90)/360]xC/2) and J45 (sin[4π(ø-90)/ 360]xC/2). RESULTS: Reporting the key results, we found that J0 significantly reduced after LASIK (p<0.001) but not J45. There was no significant association between individual pairs of pre and postoperative J0 &J45 values. CONCLUSION: WaveLight Allegretto 400Hz showed excellent results for treating patients with high astigmatism, regardless whether it is mixed or myopic astigmatism. The J45 did not reduce significantly possibly because of the low number of eyes with oblique astigmatism. There was no genuine difference postoperatively between groups treated on WaveLight Allegretto platform according to the vector analyses.

Lasik as a Solution for High Hypermetropia.

AIM: To evaluate safety and efficacy of Laser in situ Keratomileusis (LASIK) procedure for the correction of high hypermetropia. METHODS: Retrospective study of 160 patients (266 eyes) who underwent LASIK procedure for the correction of hypermetropia between +3.00 and +7.00 diopters(D) and cylinder up to 2.00D from January 2013 and August 2015. All ablations were performed with Wavelight Allegretto Eye-Q400Hzexcimer laser (Alcon, Forth Worth, TX, USA) with aberration free module and were centered on a corneal vertex. All flaps were made with Moria M2 (Moria, Antony, France) mechanical microkeratome (90µm head). Preoperative and postoperative uncorrected and corrected distant visual acuity (UDVA, CDVA), spherical equivalent (SE) and a berrometry for 5mm pupil were measured. Measurements were taken at 1 week, 1,3,6 and 12 months after the surgery. Wilcoxon Signed Ranks Test was used for statistical analysis. RESULTS: Postoperative UDVA was lower than preoperative CDVA at 1 week(p=0.001), at 1 month there was no difference (p=0.099), and at 3,6 and 12 months UDVA was better (p<0.0001). Preoperative SE was 4.69±1.20D (+3.75 to +7.50D). At 1 week SE was 0.03±0.67D (-0.50 to +0.63D), while at 1 year regressed to 0.58±0.56D (+0.25 to +0.88D). Sphere shifted from negative values targeted in treatment planning to compensate for regression to positive values. There was significant difference in SE at every time point (p<0.0005). There was a significant increase in coma (p<0.0001), trefoil (p<0.0001, p=0.0006) and spherical aberration (p=0.022, p=0.0052) at 1 week and 1 month postoperatively, without change throughout the rest of follow up. CONCLUSION: LASIK for high hypermetropia showed satisfactory results in postoperative refraction with reasonable regression without significant loss of lines of visual acuity. However, more test are necessary to asses optical quality.

Changes in Endothelial Cell Count Up to Three Years After Implantation of Toric Implantable Collamer Lenses.

PURPOSE: To determine the temporal effect of toric implantable collamer lens (TICL) implantation and location on corneal endothelial cell density (ECD) over a period of 36 months after surgery. METHODS: ECD [number of cells per square millimeter estimated using the Specular Microscope SP-1P (Topcon Europe Medical B.V., Netherlands)] data were collected from cases deemed suitable for the TICL (VTICMO, VTICM5; STAAR Surgical, Nidau, Switzerland). The preoperative refractive error (sphere and cylinder) ranged from -1.00 to -22.25 diopter sphere and from -0.50 to -5.50 diopter cylinder. ECD was evaluated at preoperative and all postoperative sessions. RESULTS: Key findings were as follows: the mean ECD (±SD, 95% confidence interval) was 2720 cells/mm (±272, 2620-2820 cells/mm) preoperatively, which was reduced to 2372 cells/mm (±325, 2250-2490 cells/mm) at 36 months postoperatively (P < 0.001). Linear regression revealed the following significant correlations between the (1) log of the change in ECD (y1) and log of preoperative ECD (x1) at 2 years postoperatively, y1 = 2.513x1-6.2816 (n = 62, r= 0.3503, P = 0.005); (2) mean ECD (y2) and log time (in months, x2), y2= 2543.7-36.997x2-38.99x2 (r=-0.9654, n = 7, P = 0.0004); and (3) mean axial distance between the front surface of the crystalline lens and the TICL back surface (y3) and time postoperatively (in months, x3), y3 = 0.1035x3-5.2808x3 +473.18 (r = 0.8512, n = 7, P = 0.015). CONCLUSIONS: Expected ECD loss after TICL implantation by 2 years postoperatively is predictable. On average, over 3 years after implantation, there is (1) an initial rapid decline in ECD, followed by a gradual fall in the rate of cell loss, and (2) a gradual fall in the distance between the TICL and the crystalline lens by 2 years postoperatively, followed by a reversal by the third year.

Excimer Lasers in Refractive Surgery.

INTRODUCTION: In the field of ophthalmology, laser technology is used in many basic and clinical disciplines and specialities. It has played an important role in promoting the development of ophthalmology. AIM: This article is designed to review the evolution of laser technology in refractive surgeries in ophthalmology, mainly focusing on the characteristics of the excimer laser applied in corneal refractive surgery. METHODS: This article was performed based on a literature review and Internet search through scientific databases such as PubMed, Scopus, Web of Science and Google Scholar. RESULT: The literature on excimer laser technology addresses the technical and physical aspects of excimer lasers including types, characteristics and commercially available lasers on the market. CONCLUSION: The conclusion on this forum aims to help understand the benefits of excimer laser use in ophthalmology, with focus on correction of refractive errors.

Unwanted Astigmatism and High-order Aberrations One Year after Excimer and Femtosecond Corneal Surgery.

SIGNIFICANCE: Small incision lenticule extraction (SMILE) is advanced as the most minimally invasive and least traumatic corneal procedure for correcting refractive errors using a single laser. Although SMILE obtains similar results to femtosecond laser in situ keratomileusis (LASIK) with spherical myopia, it has deficiencies in astigmatism correction. PURPOSE: The purpose of this study was to compare refractive outcomes and high-order aberrations (HOAs) between SMILE and femtosecond LASIK corneal procedures at 1 year post-operative. METHODS: Ninety-two patients (181 eyes) with myopia/myopic astigmatism underwent either SMILE (group 1) or femtosecond LASIK (group 2). The refractive target was to achieve emmetropia in all cases. Data were analyzed to determine significance of change in refraction and HOAs. Furthermore, astigmatism was subjected to vector analysis using the Thibos (calculation of change, Δ, in J0 and J45 values) and Alpins (calculation of difference, ΔC, between target-induced astigmatism [TIA] and surgically induced astigmatism) methods. RESULTS: Forty-five patients (89 eyes) from group 1 and 47 patients (92 eyes) from group 2 completed the study. The main significant (P ≤ .001) findings were as follows: (a) residual astigmatism was greater in group 1; (b) group 1, ΔJ0 = 1.015J0 + 0.040 (R = 0.861), ΔJ45 = 1.082J45 + 0.019 (R = 0.792), ΔC = 0.401TIA + 0.323 (R = 0.489), and mean spherical aberration increased from -0.003 (SD, ±0.059; 95% confidence interval [CI], -0.015 to 0.009) to 0.028 µm (SD, ±0.041; 95% CI, -0.037 to -0.020); and (c) group 2, ΔJ0 = 0.952J0 - 0.005 (R = 0.921), ΔJ45 = 0.962J45 - 0.002 (R = 0.923), ΔC = 0.187TIA + 0.101 (R = 0.272), mean coma reduced from 0.114 (SD, ±0.087; 95% CI, 0.096 to 0.132) to 0.077 µm (SD, ±0.059; 95% CI, 0.065 to 0.089), and trefoil from 0.089 (SD, ±0.049; 95% CI, 0.079 to 0.0990) to 0.056 µm (SD, ±0.047; 95% CI, 0.046 to 0.066). CONCLUSIONS: In comparison with SMILE, femtosecond LASIK offered better precision in the overall control of astigmatism and HOAs.

A Critical Evaluation of Refractive Outcomes Following LASIK for Moderate to High Astigmatism Using Two Excimer Laser Platforms.

PURPOSE: To calculate the surgically induced astigmatism (SIA) following LASIK and identify any association between SIA and the target induced astigmatism (TIA) at 1 year postoperatively. METHODS: The SIA was calculated using the TIA and residual astigmatism values for [A] myopic astigmatism and [B] mixed astigmatism treated with either the [I] WaveLight Allegretto EyeQ 400-Hz (Alcon Laboratories, Inc. Fort Worth, TX) or [II] Schwind Amaris 750S (Schwind eye-tech-solutions, Kleinostheim, Germany) platforms. The TIA and corresponding SIA results were analyzed using various techniques. RESULTS: Key findings were the negative SIA power (y1) was significantly correlated with negative TIA power (x1) and sine of the TIA axis (x2) as follows: [A] I, y1= 0.829x1-0.403x2-0.325 (F = 87.76, r = 0.804, P < .001, n = 127); II, y1= 0.891x1-0.037x2-0.192 (F = 240.06, r = 0.901, P < .001, n = 119) and [B] I, y1= 1.063x1+0.233x2+0.411 (F = 990.99, r = 0.881, P < .001, n = 61); II, y1= 1.029x1-0.115x2+0.322 (F = 270.12, r = 0.908, P < 0.001, n = 111). The sine of negative SIA axis (y2) was significantly correlated with negative TIA power (x1) and TIA axis (x2) as follows: [A] I, y2 = 0.951x2-0.007x1+0.008 (F = 446.58, r = 0.950, P < .001, n = 127); II, y2 = 0.856x2+0.007x1+0.105 (F = 277.18, r = 0.912, P< .001, n = 119) and [B] I, y2 = 0.953x2+0.009x1+0.075 (F = 362.6, r = 0.963, P < .001, n = 61); II, y2 = 0.977x2-0.004x1+0.002 (F = 2910.9, r = 0.990, P < .001, n = 111). CONCLUSIONS: The predicted SIA power was up to 12% less than expected in cases of -6.00 diopters cylinder treated for myopic astigmatism using the Allegretto platform. The mean predicted angle of error (the angle between the SIA and TIA axes) was less than 4°, increasing to 12° for against-the-rule astigmatism. The Allegretto platform tended toward a clockwise axis rotational error, whereas the Amaris platform tended toward the opposite. [J Refract Surg. 2017;33(2):104-109.].

Comparison of Verisyse and Veriflex Phakic Intraocular Lenses for Treatment of Moderate to High Myopia 36 Months after Surgery.

PURPOSE: To compare refractive stability, endothelial cell count (ECC), incidence of complications, and patients' satisfaction between a rigid Verisyse (group I, n = 198) and foldable Veriflex (group II, n = 212) phakic intraocular lenses (pIOL) over 36 months postop. MATERIALS AND METHODS: This was a retrospective study. Patients' satisfaction and incidence of photic phenomena were evaluated at one month and one year postop. Data were analyzed to determine difference between groups for astigmatism, mean spherical equivalent (MRSE), uncorrected (UDVA) and corrected (CDVA) monocular distance visual acuity, complication rate (acute and chronic), and ECC. Differences were considered statistically significant when p < 0.05. RESULTS: Group II cases had significantly higher UDVA, CDVA, and lower astigmatism during the entire follow-up. There was no significant difference in mean MRSE or mean ECC postoperatively. In both groups, mean ECC reduced significantly at one month postop, followed by a gradual linear decline between 1 and 36 months of 22.4 cells/mm2/annum (group I) and 13.32 cells/mm2/annum (group II). Overall complication rates were ≤ 10% with no significant inter-group differences. Group I patients reported lower incidence of halos at one month but more problems with night vision at one year compared with group II. Overall satisfaction was high and total incidence of reported photic phenomena was low. CONCLUSION: Both Verisyse and Veriflex pIOLs are effective in correcting myopia. The Veriflex lens demonstrated better refractive outcome; however, subclinical inflammation observed in the Veriflex group and potential influence of inflammation on ECC loss require further investigation.