Spherical Error Research Articles

Long-Term Refractive Outcome of Small Incision Lenticule Extraction in Very High Myopia

To assess the stability, safety, predictability, and efficacy of small incision lenticule extraction (SMILE) in high myopia. The study was conducted as a retrospective noncomparative analysis of the records of 495 eyes of 270 patients treated by the ReLEx SMILE technique for a mean spherical myopic error of -12.84 ± 2.47 D (range: -10.0 to -14.0 D) combined with a mean astigmatism of -1.17 ± 1.34 D (up to -4.0 D). The mean LogMAR corrected distance visual acuity (CDVA) was 0.2 ± 0.6. In this study, 225 patients had the bilateral SMILE procedure, whereas 45 patients had a single eye treated with SMILE. One month after surgery, the mean refractive error was 20.72 ± 0.88 D (range: +1 to 21.5 D), and the mean postoperative astigmatism was -0.83 ± 1.04 D. The mean LogMAR UDVA was 0.2 ± 0.34. In the last follow-up visit, 3 years after surgery, all the before mentioned parameters were the same or within minimal changes with no statistically significant difference from the earlier results. However, the spherical error demonstrated a significant change from -0.72 ± 0.88 D at 1 month to -1.17 ± 1.01 D at the end of the follow-up. However, this change had an insignificant visual impact. At the end of the follow-up period, approximately 94% of patients had unchanged CDVA or gained one or more lines, 6% lost one line of CDVA, and 1% lost 2 lines. SMILE may be effective and safe, with a stable and predictable outcome for correction of very high myopia.

RPGR-Associated Dystrophies: Clinical, Genetic, and Histopathological Features.

This study describes the clinical, genetic, and histopathological features in patients with RPGR-associated retinal dystrophies. Nine male patients from eight unrelated families underwent a comprehensive ophthalmic examination. Additionally, the histopathology of the right eye from a patient with an end-stage cone-rod-dystrophy (CRD)/sector retinitis pigmentosa (RP) phenotype was examined. All RPGR mutations causing a CRD phenotype were situated in exon ORF15. The mean best-corrected visual acuity (BCVA, decimals) was 0.58 (standard deviation (SD)): 0.34; range: 0.05–1.13); and the mean spherical refractive error was −4.1 D (SD: 2.11; range: −1.38 to −8.19). Hyperautofluorescent rings were observed in six patients. Full-field electroretinography responses were absent in all patients. The visual field defects ranged from peripheral constriction to central islands. The mean macular sensitivity on microperimetry was 11.6 dB (SD: 7.8; range: 1.6–24.4) and correlated significantly with BCVA (r = 0.907; p = 0.001). A histological examination of the donor eye showed disruption of retinal topology and stratification, with a more severe loss found in the peripheral regions. Reactive gliosis was seen in the inner layers of all regions. Our study demonstrates the highly variable phenotype found in RPGR-associated retinal dystrophies. Therapies should be applied at the earliest signs of photoreceptor degeneration, prior to the remodeling of the inner retina.

Changes in forward light scatter parameters as a function of refractive error in young adults

Background/aimsSome aspects of visual performance worsen with increasing myopia. Whilst the underlying causes are not always clear, reduction in retinal image quality is often attributed to structural changes in the posterior myopic eye. Forward light scatter, originating principally from the cornea and lens, is known to produce veiling glare which subsequently reduces retinal image contrast. It is therefore of interest to investigate whether forward light scatter varies with refractive error.MethodsThirteen young-adult subjects (18–25 years), with mean spherical errors (MSE ± sd, D) RE, − 1.69 ± 2.02 (range 0.38 to − 4.75); LE, − 1.91 ± 1.94 (range 0.50 to − 4.63) underwent binocular assessment of forward light scatter using the AVOT light scatter test. Five glare annuli, with effective eccentricities ranging from 2 to 10°, were used to estimate parameters, k and n, which define the light scatter function of the eye. These were then used to calculate the area under the light scatter function (k′) and the total volume of light scatter (k″).ResultsSignificant correlation was found between increasing myopia and k′ values (RE, p < 0.05; r = 0.64; LE, p < 0.05, r = 0.66). Neither the ‘volume’ of light scatter (k″), the parameter, n, which controls the angular distribution of light scatter, or the straylight parameter constant, k, were significantly correlated with refractive error (p > 0.05 for both eyes). Axial length was also not correlated with any of the light scatter parameters measured.ConclusionThe preliminary data from this study provide evidence that some light scatter parameters may be correlated with refractive error. Further studies are needed to characterize how changes in the anterior media of the eye, and inclusion of a wider range of refractive errors, may affect forward light scatter.

New Bubble Mitomycin C Application Technique for Haze Prevention following Customized Photorefractive Keratectomy

Present investigation deals with a pilot study in which a new technique for applying mitomycin C directly onto the ablated corneal surface in the form of an injector-administered bubble. Here, a technique was introduced and the observations made with this technique in this pilot study involving 125 patients who received wave front bilateral photorefractive keratectomy. Mitomycin C was administered using the common minisponge application technique in one eye and mitomycin C was administered using the new bubble technique in the other eye. Photorefractive keratectomy presentation was compared between the minisponge-treated and bubble-treated eyes. Visual parameters such as visual acuity, spherical refractive error and cylindrical refractive error were similar in eyes across the two treatments before and after wave front photorefractive keratectomy. None of the minisponge-treated or bubble-treated eyes developed clinically evident photorefractive keratectomy haze. Compared to the minisponge-treated eyes, bubbletreated eyes showed faster healing (3 d vs. 5 d for contact lens bandage removal) and faster visual recovery (≤5 d vs. 7-10 d). In conclusion, the new bubble technique for applying mitomycin C after wave front photorefractive keratectomy provided a safe, effective and time-saving alternative to the standard mini sponge mitomycin C application technique.

Ocular biometry in an adult Ghanaian population

Purpose: To measure ocular biometry and its correlates in an adult population. Materials and Methods: The measured biometric data included central corneal thickness (CCT), corneal power (K), anterior chamber depth (ACD), lens thickness (LT), vitreous chamber depth (VCD), axial length (AL), and spherical refractive error (SER) in 162 adult eyes. Results: The mean CCT was 506.7 ± 39.2 μm, mean K was: K1 = 42.50 ± 2.00 D, K2 = 43.50 ± 2.44 D, the mean AL was 24.2 ± 1.3 mm, ACD had a mean of 3.5 ± 0.6 mm, LT (mean of 3.9 ± 0.8 mm), VCD (mean of 16.4 ± 1.39 mm), and SER ranged from -10.00 D – +8.00 D. There were no significant correlations between the CCT and SER (r = 0.06, P = 0.44), LT (r = 0.06, P = 0.59), ACD (r = −0.12, P = 0.12), AL (r = −0.02, P = 0.98), and VCD (r = −0.05, P = 0.68). Pearson's correlation coefficient tests showed that AL was significantly positively correlated with ACD (r = 0.4, P

Doğumsal Tek Taraflı Gözyaşı Kanal Tıkanıklığı Olan Olgularda Refraktif Durum

Objective: To investigate the refractive status and frequency of amblyopia risk factors in children who underwent probing for unilateral nasolacrimal duct obstruction (NLDO). Material and Methods: This descriptive cross-sectional study included 65 consecutive children with unilateral congenital NLDO who were still symptomatic at one year examination and necessiated nasolacrimal duct probing. A complete ophthalmic evaluation including cycloplegic refraction was performed. The spherical, cylindrical and spherical equivalent retinoscopy measurements of both eyes were noted. The risk factors for amblyopia and differences between refractive values of both eyes were evaluated. Results: The mean age at presentation was 20.4±9.2 months (range, 12 to 48 months). The left eye was involved in 30 (46.2 %) patients. Thirty-five subjects (54 %) were female. Nine children had amblyopia risk factors (13.8%). There was no statistically significant difference regarding cylindrical refractive error, spherical refractive error and spherical equivalent (p=0.9, p=0.9 and p=0.5 respectively) between two eyes. Conclusion: In the current study, no statistically significant difference was found between refractive values of both eyes. One tenth of children in our study group were found to be under risk of amblyopia mostly due to high astigmatism. Further studies about the effect of blurred vision on visual development of both eyes and binocular vision may provide more information about the refractive status in this group of patients.

Macroeconomic Drivers of Private Equity Penetration in Sub-Saharan African Countries

The objective of this study is to investigate in to the drivers of private equity penetration in Cameroon, Nigeria, Ghana, Kenya and South Africa. Secondary data was collected from private equity and venture capital data bases (CapitalIQ, Preqin, Burgiss and Mergermarket), World Bank development indicators, regional private equity and venture capital associations and country specific stock market websites. The Panel Two-Stage Least Squares Instrumental Variables (2SLS IV), Panel Corrected Standard Errors (PCSE) and Feasible Generalised Least Squares (FGLS) estimation techniques were used. This was due to potential problems of endogeneity and spherical errors of serial correlation, heteroskedasticity, cross sectional dependence and multicollinearity. The results using the 2SLS IV estimation technique show that stock market capitalisation, GDP per capita, banking credit to private sector, real exchange rate and private investments are key macroeconomic drivers of private equity penetration in the selected Sub-Saharan African countries. Inflation had negative and insignificant effect on private equity penetration in the selected countries. The results using the PCSE and FGLS estimation techniques show that the signs of all the variables remain the same as was the case in the 2SLS IV estimation technique though the magnitudes were different. However, the results of PCSE and FGLS estimation techniques show that banking credit to private sector is significant in the FGLS model while private investments is significant in the PCSE model. GDP per capita, real exchange rate, stock market capitalisation and inflation are significant in both the PCSE and FGLS estimation techniques.

Bioengineered corneal stroma: from laboratory to clinical adoption

AbstractBlindness caused by corneal stromal disease and injuries affects millions worldwide, with the greatest burden in low‐ to middle‐income countries with inadequate donation and tissue banking infrastructure to meet the demand for sight‐restoring corneal transplantation. We bioengineered a regenerative cell‐free corneal scaffold from medical‐grade type I collagen and developed a minimally‐invasive implantation method avoiding the need for surgical suturing or long‐term immunosuppression. Applying good manufacturing practices and third‐party certified biocompatibility, toxicity, sterility and long‐term shelf life studies, sterile corneal scaffolds were tested in preclinical animal models and in a first clinical case series. Scaffolds integrated with recipient tissue and supported host cell ingrowth without inflammation or scarring. 22 subjects with advanced keratoconus were implanted with the bioengineered scaffold without complications. During 6–12 months of follow‐up, no rejection, inflammation, vascularization or adverse event occurred. Visual acuity, spherical refractive error, keratometry, corneal thickness and volume all improved significantly in the cohorts. Initially contact lens‐intolerant patients were tolerant postoperatively and are eligible for refractive surgery to optimize visual acuity. Results indicate bioengineered scaffold implantation can restore vision in patients with advanced stromal disease, avoiding more invasive procedures and the need for donor tissue.

Validation of an Independent Web-Based Tool for Measuring Visual Acuity and Refractive Error (the Manifest versus Online Refractive Evaluation Trial): Prospective Open-Label Noninferiority Clinical Trial.

BackgroundDigital tools provide a unique opportunity to increase access to eye care. We developed a Web-based test that measures visual acuity and both spherical and cylindrical refractive errors. This test is Conformité Européenne marked and available on the Easee website. The purpose of this study was to compare the efficacy of this Web-based tool with traditional subjective manifest refraction in a prospective open-label noninferiority clinical trial.ObjectiveThe aim of this study was to evaluate the outcome of a Web-based refraction compared with a manifest refraction (golden standard).MethodsHealthy volunteers from 18 to 40 years of age, with a refraction error between –6 and +4 diopter (D), were eligible. Each participant performed the Web-based test, and the reference test was performed by an optometrist. An absolute difference in refractive error of <0.5 D was considered noninferior. Reliability was assessed by using an intraclass correlation coefficient (ICC). Both uncorrected and corrected visual acuity were measured.ResultsA total of 200 eyes in 100 healthy volunteers were examined. The Web-based assessment of refractive error had excellent correlation with the reference test (ICC=0.92) and was considered noninferior to the reference test. Uncorrected visual acuity was similar with the Web-based test and the reference test (P=.21). Visual acuity was significantly improved using the prescription obtained by using the Web-based tool (P<.01). The Web-based test provided the best results in participants with mild myopia (ie, <3 D), with a mean difference of 0.02 (SD 0.49) D (P=.48) and yielding a corrected visual acuity of >1.0 in 90% (n=77) of participants.ConclusionsOur results indicate that Web-based eye testing is a valid and safe method for measuring visual acuity and refractive error in healthy eyes, particularly for mild myopia. This tool can be used for screening purposes, and it is an easily accessible alternative to the subjective manifest refraction test.Trial RegistrationClinicaltrials.gov NCT03313921; https://clinicaltrials.gov/ct2/show/NCT03313921.

Corneal elevation changes after forced eyelid closure in healthy participants and in patients with keratoconus

BackgroundTo assess pointwise corneal elevation changes after forced eyelid closure test (FECT) in the eyes of healthy subjects and in eyes with keratoconus.MethodsTwenty‐nine subjects with keratoconus and 31 healthy volunteers were evaluated. Patients with keratoconus who had corneal hydrops, apical scarring, corneal thickness ≤ 400 μm, ocular surface disease, contact lens wear on the examination day and a history of corneal cross‐linking were excluded. Exclusion criteria for healthy participants were spherical error > +3.00 D and < −3.00 D, corneal astigmatism > 1.50 D, corneal curvature > 47 D, ocular allergy, clinical findings and family history of keratoconus. Pentacam was performed before and after 20-seconds of FECT and raw data were extracted from the built‐in software. Pointwise anterior and posterior elevation changes in the central 8-mm cornea were assessed using paired samples t‐test and heat maps were constructed to reflect mean changes and statistically significant data points. Statistical significance was assumed at p < 0.01.ResultsAge and gender were similar between healthy subjects (24.5 ± 1.6-years, 46.4 per cent female) and subjects with keratoconus (28.6 ± 9.2-years, 46.4 per cent female, p = 0.19, 0.61, respectively). Healthy eyes displayed posterior depression clustering in the inferotemporal and inferonasal areas (mean change: −4.5 ± 7.8 μm and −5.2 ± 9.8 μm, respectively, all p < 0.01). In contrast, keratoconus eyes exhibited a wider area of posterior elevation clustering in the inferior cornea (mean change: 8.1 ± 14.5 μm, all p < 0.01) with a small extension in the inferotemporal cornea (mean change: 12.1 ± 22.3 μm, all p < 0.01).ConclusionFECT elicits corneal elevation changes mainly in the inferior cornea with the change being more pronounced and wider in eyes with keratoconus.

Phakic Intraocular Lens Implantation After Deep Anterior Lamellar Keratoplasty: Retrospective Case Series Analysis With Long-Term Follow-Up.

PurposeTo report outcomes of phakic intraocular lens (IOL) implantation after deep anterior lamellar keratoplasty (DALK) to correct high ametropia.SettingCentro Hospitalar Universitário do Porto, Portugal.MethodsRetrospective case series with 11 eyes submitted to phakic IOL implantation after DALK. Main outcomes measured were uncorrected and corrected distance visual acuity (UDVA and CDVA), refractive error components, tomographic parameters and endothelial cell density (ECD). The minimum follow-up was 3 years for all cases.ResultsMean ECD loss was 8.7±6.7% at 1 year, 13.1±8.6% at 3 years (n=11; p=0.016, p=0.007, respectively) and 14.0±20.4% at 5 years (n=5, p=0.212). Mean logMAR UDVA increased from 1.27±0.90logMAR preoperatively to 0.16±0.15logMAR postoperatively (p≤0.001) and no statistically significant differences were registered during follow-up. All patients gained at least 5 lines of UDVA. 54.5% of the eyes gained 1 line in CDVA postoperative and only one eye lost one CDVA line through follow-up. Efficacy and safety indexes at 1 and 3 years were 1.01–0.97 and 1.24–1.21, respectively. Mean spherical equivalent was reduced from −7.84±4.63 D preoperatively to −1.05±1.07 D postoperatively (p=0.001). Mean percentage of reduction in refractive cylinder and spherical error was 83.8±15.8% and 73.1±31.5%, respectively, p≤0.001 for both. In one eye there was a significantly gradual ECD loss over 5 years follow-up and the patient will be submitted to IOL explant.ConclusionPhakic IOLs were effective for correction high ametropia after DALK, showing high efficacy and safety indexes with stability over time. However, it was registered a continuing endothelial cell loss postoperatively, which assumed to be higher than those reported in eyes without DALK.

Clinical Outcomes of an Asymmetric Model of Intrastromal Corneal Ring Segments for the Correction of Keratoconus

To evaluate the clinical outcomes of a new model of intrastromal corneal ring segments (ICRSs) (Keraring AS) in patients with keratoconus and quantify subsequent changes in refraction and corneal topography. This nonrandomized, single-center, retrospective observational study explores the effect of progressive thickness ICRS implantation in patients with keratoconus with a 3-month follow-up. After creating an intrastromal tunnel using a femtosecond laser, 1 or 2 ICRSs of progressive thicknesses (150/250 μm or 200/300 μm) and 160-degree arc length were implanted. Changes in uncorrected distance visual acuity, best-corrected distance visual acuity, refractive outcomes, corneal astigmatism, and maximum keratometry readings were recorded before and after surgery. The study cohort consisted of 82 patients (104 eyes) with a mean age of 31.2 ± 10 years. At 3 months, ICRS implantation significantly improved uncorrected and corrected visual acuities from 0.82 to 0.46 (logarithm of the minimum angle of resolution [LogMAR]) and from 0.31 to 0.21 (LogMAR), respectively (P < 0.001). The mean spherical error reduced from -1.74 diopters (D) to -0.90 D (P < 0.001), and the mean cylindrical error reduced from -4.22 D to -2.01 D (P < 0.001). The manifest refraction spherical equivalent reduced from -3.85 D to -1.91 D (P < 0.001). All topographic parameters were reduced, including maximum keratometry (53.6 D vs. 50.3 D) and keratometric astigmatism (-4.6 D vs. -2.2 D) (P < 0.001). The Keraring AS provides a new, apparently safe, and effective means of improving visual acuity and reducing the refractive error and mean keratometry in eyes with asymmetric keratoconus.

Status of Residual Refractive Error, Ocular Aberrations, and Accommodation After Myopic LASIK, SMILE, and TransPRK.

To analyze residual refractive error, ocular aberrations, and visual acuity (VA) during accommodation simultaneously with ocular aberrometry in eyes after laser-assisted in situ keratomileusis (LASIK), small incision lenticule extraction (SMILE), and transepithelial photorefractive keratectomy (TransPRK). Ocular aberrometry (Tracey Technologies, Houston, TX) was performed 3 months after LASIK (n = 95), SMILE (n = 73), and TransPRK (n = 35). While measuring the aberrations, VA was measured at distance (20 ft), intermediate (60 cm), and near (40 cm) targets. The examinations were done monocularly. A parallel group of age-matched normal eyes (n = 50) with 20/20 Snellen distance VA also underwent aberrometry. Distribution of residual spherical error of LASIK eyes matched the normal eyes the best, followed by SMILE and TransPRK. However, the distribution of cylindrical error of the SMILE eyes was distinctly different from the rest (P < .05). The SMILE eyes tended to be undercorrected by approximately 0.25 diopters (D) on average at all reading targets compared to LASIK eyes (P < .05). The undercorrection was greater when the magnitude of the preoperative cylinder exceeded 0.75 D (P < .05). The VA of LASIK and SMILE eyes was similar to normal eyes at all targets, but the TransPRK eyes were marginally inferior (P < .05). Only the ocular defocus changed differentially between the study groups during accommodation and the magnitude of change was least for TransPRK eyes (P < .05). However, postoperative near and intermediate accommodation of LASIK eyes were similar to normal eyes, followed by SMILE eyes and then TransPRK eyes. The refractive and aberrometric status of the LASIK eyes was closest to the normal eyes. The SMILE procedure may benefit from slight overcorrection of the preoperative refractive cylinder. [J Refract Surg. 2019;35(10):624-631.].

Design, methodology, and preliminary results of the follow-up of a population-based cohort study in rural area of northern China: Handan Eye Study.

Background:Handan Eye Study (HES), a large population-based cohort study in rural area of northern China, was one of the few studies focusing on the major eye diseases of rural Chinese population. The aim of this study was to introduce the design, methodology and to assess the data quality of the follow-up phase of HES.Methods:All participants were recruited in Yongnian county of Handan city between 2012 and 2013. Main outcomes were measured by visual quality scales and ocular examinations. We performed the Chi-square test to make comparison of categorical data among groups, One-way analysis of variance and Kruskal-Wallis test was applied to make comparison of continuous data among groups, a post-hoc test was done to make further pairwise comparison. Inter-class correlation coefficients (ICCs) and Kappa coefficients were used to evaluate the consistency between different operators. Logistic regression was used to explore the influence factors of death, odds ratio (OR) and 95% confidence interval (CI) were used to estimate the effect size of each influence factor.Results:The follow-up rate was 85.3%. Subjects were classified into three groups: the follow-up group (n = 5394), the loss to follow-up group (n = 929), and the dead group (n = 507), comparison of their baseline information was done. Compared with the other two groups, age of the dead group (66.52 ± 10.31 years) was the oldest (Z = 651.293, P < 0.001), male proportion was the highest (59.0%) (χ2 = 42.351, P < 0.001), only 65.9% of the dead finished middle school education (Z = 205.354, P < 0.001). The marriage percentage, body mass index (BMI), best-corrected visual acuity (BCVA), and intra-ocular pressure of the dead group was the lowest either. Spherical equivalent error (SER) of the dead group was the highest. Besides, history of smoking, hypertension, diabetes, and heart disease were more common in the dead group. Multivariate analysis showed that age (OR = 1.901, 95% CI: 1.074–1.108), gender (OR = 0.317, 95% CI: 0.224–0.448), and BCVA (OR = 0.282, 95% CI: 0.158–0.503) were associated with death. While between the follow-up group and the loss to follow-up group, there was only difference on age, gender, BMI, systolic blood pressure and SER. The Cronbach coefficients of all scales used in the follow-up were ≥0.63 and the cumulative variances were ≥0.61, indicating good reliability and validity. The ICCs and Kappa coefficients between different operators were ≥0.69.Conclusions:HES has a high follow-up rate and a low risk of loss to follow-up bias. Age, gender, and BCVA are influence factors of death. Specifically, male subjects are at a higher risk of death than female, age is a risk factor of death while BCVA is a protective factor for death.

Experimental study on hybrid compensation testing of an off-axis convex ellipsoid surface.

Aspherical surfaces can provide significant benefits to a wide variety of optical systems, but manufacturing high-precision aspherical surfaces has historically been limited by the ability to measure them. Null testing has always been the ideal method in aspherical measurement. However, in many cases, it is hard to realize null testing for complex surfaces, especially for convex surfaces in complicated forms. In this paper, we propose a hybrid compensation method combining a spherical mirror and a computer generated hologram (CGH) to achieve the null testing of the convex aspherical surface. Firstly, we introduce our self-developed mathematical models in the hybrid compensation method, including optics alignment model, distortion correction model and spherical surface error removing model. Then the performance of our proposed method is analyzed by a null testing experiment of an off-axis convex ellipsoid mirror. The experimental result shows that the proposed method can accomplish the hybrid compensation testing of convex aspherical surfaces effectively, and it can also bring much to the application of our method in convex aspherical surface testing.

Comparison of accuracy of haigis and SRK II formula for intraocular lens power calculation in eyes with short axial length

Comparison of accuracy of haigis and SRK II formula for intraocular lens power calculation in eyes with short axial length - IJCEO- Print ISSN No: - 2395-1443 Online ISSN No:- 2395-1451 Article DOI No:- 10.18231/j.ijceo.2019.090, Indian Journal of Clinical and Experimental Ophthalmology-Indian J Clin Exp Ophthalmol

Keratoconus Screening Among Myopic Children.

AimTo assess the topographic corneal changes and the incidence of keratoconus among children with high myopia.SettingsIt is a prospective study, in which 174 eyes of children with high myopia were studied in the period between August 2015 and June 2018.MethodsAll patients were examined to assess the refractive error and corneal examination using Scheimpflug camera to evaluate different corneal parameters.ResultsStudied children aged between 6 and 14 years (11.05±1.98). Males represented 54% of the cases (n=94). The mean spherical error was −7.75±2.97 ranging from −6 to −13.50D. The mean cylindrical error was −4.12±1.78D (−1 to −8). Regarding corneal examination, data recorded were those about maximum K reading (kmax), thinnest location, highest anterior and posterior elevation in 4mm zone, and higher-order corneal aberrations. Analysis of the obtained data revealed 16 eyes (9.2%) with keratoconus. These eyes were considered as a separate group and compared with the remaining eyes. There was significant difference in kmax (p= 0.03), anterior elevation, and posterior elevation (p=0.01 for both). Regarding myopia or astigmatism, there were no significant differences when compared with normal eyes. But high myopia with low astigmatism were found in five eyes of them (31.2%). The main statistically different aberrations were vertical coma (−2.04±0.99) (p=0.01) and spherical aberrations (−0.9±0.78) (p=0.02). Regarding gender, there were 11 eyes in boys (68.7%), and this was statistically significant (p=0.01). Vernal keratoconjunctivitis with frequent eye rubbing was found in 6 eyes (37.5%).ConclusionChildren with high myopia irrespective of the degree of astigmatism may have corneal abnormalities which are more pronounced in cases with vernal keratoconjunctivitis. Corneal examination should be performed for highly myopic children to detect any corneal abnormality and to treat it as early as possible.

Short Interruptions of Imposed Hyperopic Defocus Earlier in Treatment are More Effective at Preventing Myopia Development

The purpose of this study was to evaluate the effect of interrupting negative lens wear for short periods early or late during the development of lens-induced myopia in marmosets. Sixteen marmosets were reared with a −5D contact lens on their right eye (plano on contralateral eye) for 8 weeks. Eight marmosets had lenses removed for 30 mins twice/day during the first four weeks (early interruption) and eight during the last four weeks (late interruption). Data were compared to treated controls that wore lenses continuously (N = 12) and untreated controls (N = 10). Interocular differences (IOD) in vitreous chamber (VC) depth and central and peripheral mean spherical refractive error (MSE) were measured at baseline and after four (T4) and eight (T8) weeks of treatment. Visual experience during the interruptions was monitored by measuring refraction while marmosets were seated at the center of a 1 m radius viewing cylinder. At T4 the eyes that were interrupted early were not different from untreated controls (p = 0.10) and at T8 had grown less and were less myopic than those interrupted later (IOD change from baseline, VC: +0.07 ± 0.04 mm vs +0.20 ± 0.03 mm, p < 0.05; MSE: −1.59 ± 0.26D vs −2.63 ± 0.60D, p = 0.13). Eyes interrupted later were not different from treated controls (MSE, p = 0.99; VC, p = 0.60) and grew at the same rate as during the first four weeks of uninterrupted lens wear (T4 − T0: 3.67 ± 1.1 µm/day, T8 − T4: 3.56 ± 1.3 µm/day p = 0.96). Peripheral refraction was a predictive factor for the amount of myopia developed only when the interruption was not effective. In summary, interrupting hyperopic defocus with short periods of myopic defocus before compensation occurs prevents axial myopia from developing. After myopia develops, interruption is less effective.

Relationship between early structural changes at cornea incision sites and surgical outcomes after phacoemulsification.

To assess the early structural changes at clear corneal cataract incision sites and surgical outcomes using anterior segment optical coherence tomography (AS-OCT). We evaluated 80 eyes of 59 patients who underwent phacoemulsification with a clear corneal incision. All incisions were evaluated 1wk, 1, and 3mo postoperatively using AS-OCT and analyzed regarding angle, length of the incision, maximal corneal thickness at the incision, and if present, corneal endothelial gap length and incision gap area. The patients were divided into two groups according to whether or not an endothelial gap was present at 1wk postoperatively (endothelial gap, group 1; no endothelial gap, group 2). We analyzed the difference in patient and surgical factors between the two groups, and compared the surgical outcome and the refractive outcome. An endothelial gap was observed in 56 (70.0%) of 80 eyes at 1wk postoperatively but not at 3mo postoperatively. The mean patient age was significantly higher in group 1 than in group 2. The longer the length of the corneal incision and the steeper the incision angle, the greater the length and area of the endothelial gap. In group 1, the mean change in mean keratometry of the anterior cornea was significantly greater than in group 2, and the spherical equivalent (SE) and mean numerical error indicated significant myopic changes at 1wk postoperatively. The risk of an endothelial gap increases with patient age and a long corneal incision and steep incision angle. The presence of an endothelial gap after surgery may affect the early postoperative corneal curvature and SE.

COMPARISON OF CLINICAL OUTCOMES AFTER FEMTOSECOND ASSISTED LASER IN SITU KERATOMILEUSISAND IMPLANTABLE COLLAMER LENS IMPLANTATION FOR CORRECTION OF HIGH MYOPIA

Purpose: To compare efficacy, safety and stability of Femtosecond assisted LASIK andimplantable collamer lens implantation in correction of high myopia. Methods: This study was nonrandomized comparative prospective consecutive interventional study. It included 74 eyes withhigh myopia (≥ -6 Ds) of 40 patients attended to the outpatient ophthalmic clinic of Sohaguniversity hospitals from the period from Jan.2016 to Jan.2017. The patients were divided intotwo groups depending on: Degree of myopia, corneal thickness and corneal tomography. Thefirst group (34 eyes) of 20 patients were subjected to implantable collamer lensesimplantation and the second group (40 eyes) of 40 patients were subjected to femtosecondassisted LASIK. Results: Group one (ICL group) showed UCVA preoperative was (1.90±0.29)and UCVA postoperative was (0.27±0.21) with (p-value<0.000*). BCVA preoperative was(0.526±0.272) and that of BCVA postoperative was (0.217±0.128) with (p-value<0.001*), whichmeans that BCVA postoperative was better than what was expected from the BCVA preoperative. Spherical error decreased from (-13.576±3.945) preoperative to (-0.0385±0.821) postoperative with (p-value<0.000*).Cylindrical error preoperative was (-1.134±0.617) and postoperative was (-0.352±0.250) with (p-value<0.000*).Spherical equivalent preoperative was (-15.173±4.079) and that of postoperative was (-0.269±0.787) with (p-value<0.000*). Pachymetry preoperative was (518.153±22.981) and postoperative was (521± 22.304) with (p-value <0.140).Group two (Femtosecond assisted LASIK) UCVA preoperative was (1.42±0.27) and UCVApostoperative was (0.366±0.21) with (p-value<0.000*).There wasnit significant difference betweenBCVA preoperative and postoperative. Spherical error preoperative was (-8.398±1.733) and postoperative (-0.796±1.186) with (p-value<0.000*). Cylinder error mean value preoperative was (-1.648±0.838) corrected to (-0.765±0.423) with (p-value< 0.005). Spherical equivalent preoperative was (-9.213±1.899) and that of postoperative is (-0.935±1.11) with (p-value<0.000*).Pachymetry preoperative was (535.111±26.33) and postoperative (419.88± 43.063) with (pvalue<0.000*). Conclusion: Both implantable collamer lens and Femtosecond assistedLASIK proved high efficacy and safety but implantable collamer lens showed more stability forhigh myopic patients.