Simple Myopia Research Articles

Initial Single-Site Surgical Experience with SMILE: A Comparison of Results to FDA SMILE, and the Earliest and Latest Generation of LASIK.

IntroductionThe primary objective was to show our initial surgical single-site experience with small incision lenticule extraction (SMILE) after the official enrollment in March 2017 following Food and Drug Administration (FDA) approval for simple myopia in late 2016 in the United States and, subsequently, compare our results to the earliest and most advanced generation of excimer platforms for laser-assisted in situ keratomileusis (LASIK) surgery.MethodsThis was a retrospective single-site study of 68 eyes from 35 patients who had SMILE surgery. The patients’ preoperative and postoperative uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest sphere, manifest cylinder, intraoperative complications, and preoperative and postoperative visual symptoms were collected. We compared our findings to the results from the FDA SMILE study, and to the three earliest (1999–2000) and three of the most updated (2013–2016) platforms for LASIK.ResultsThe cumulative UDVA was 20/20 and 20/40 or better in 74% and 100% of patients, respectively. The intended target refraction was within ± 0.5 and ± 1.00 D in 80% and 93% of cases, respectively. The prevalence of dry eyes decreased by nearly half from 1-week to the 6-month postoperative interval. Patients noted improvement in glare (17%), halos (17%), fluctuation (25%), and depth perception (8%) at the 6-month interval compared to preoperative levels.ConclusionsThis study’s findings are consistent with current SMILE reports. Notably, the results are superior to the earliest generation of LASIK, however inferior to the latest excimer platforms. SMILE does meet the efficacy and safety criteria met by FDA; however, there is a definite need for further improvement to reach the superior refractive outcomes produced by the latest generation of LASIK platforms.

Refractive Errors Among Medical Students

Introduction: Refractive errors are becoming a problem in many societies, with prevalence rates of myopia in many Asian urban countries reaching epidemic proportions. This study aims to determine the prevalence rates of various refractive errors among medical students of Kist Medical College Teaching Hospital, Nepal.Materials and Methods: Medical students were included in the study. Demographic data was obtained via questionnaires filled in by the students after taking informed verbal consent. Refractive error measurements were determined by dry retinoscopy and additional cycloplegic refraction as and when needed.Results: The prevalence rate of simple myopia was 64.81% and 3.7% had high myopia. Hyperopia (Hypermetropia) was present in 1.8% of the participants while overall astigmatism prevalence rate was 29.6% among medical students. Conclusion: Prevalence rates of myopia in medical students are found to be quite high.Conclusions: Prevalence rates of myopia in medical students are found to be quite high.Nepalese Medical Journal, vol.1, No. 1, 2018, page: 21-23

Advances of optical coherence tomography angiography in myopia

Optical coherence tomography angiography (OCTA) is an noninvasive, rapid and reproducible technology which can provide high resolution view of the vascular structures and quantifies the vessel densities in retina and choroid. Myopia can be divided into simple myopia and pathologic myopia. The mechanism of myopia is not clear while it is closely related to the vessel density. For simple myopia, OCTA can monitor the course and deepen the understanding of myopia by quantifying the vessel densities in each layers and sectors and the foveal avascular zone. For pathologic myopia, OCTA has an advantage of observing the choroidal neovascularization, chorioretinal atrophy and Zinn-Haller arterial circle which can contribute to the early diagnosis and management and follow-up to estimate the prognosis. However, there are several limitations of OCTA which need to be improved, including in the process of acquiring high-quality images, accurate layering and dynamic observation. Key words: Myopia/diagnosis; Myopia, degenerative/diagnosis; Tomography, optical coherence; Review

Visual acuity and refractive changes among pregnant women in Enugu, Southeast Nigeria.

Introduction:Pregnancy has been associated with changes in the eye which could be physiological, pathological, or exacerbation of pre-existing ocular conditions. Visual acuity (VA) and refractive error (RE) changes are part of the physiological changes that may occur during pregnancy.Objective:The objective of the present study was to investigate changes in VA and RE across two different trimesters and six weeks postpartum among pregnant women in Enugu, southeast, Nigeria.Materials and Methods:A longitudinal study was adopted and pregnant women in their second trimester attending antenatal clinic at University of Nigeria Teaching Hospital, Ituku-Ozalla, Enugu were consecutively recruited. A questionnaire was used to obtain information on their sociodemographic and clinical characteristics. Visual acuity was measured and refractive error monitored in second and third trimesters and 6 weeks after delivery.Results:The mean age of women was 30.81 (±5.49) years and a majority of them were civil servants. There was a worsening of VA for distance in more women in the third trimesters compared to the second trimester. There was no significant change in VA for near throughout the study period. There was an increased myopic shift in more pregnant women during the third trimester (40; 40.0%) compared to second trimester (36; 36.0%). The most common refractive error found among the women was simple myopia. These changes resolved six weeks postpartum.Conclusion:Pregnancy worsened VA for distance and the most common RE in pregnant women was simple myopia. However, these changes resolved during the postpartum period.

Demographic profile of newly detected refractive errors among schoolgoing children in Thrissur district of Kerala

Aim: This study aims to analyze the demographic profile of newly detected refractive errors among schoolgoing children in Thrissur district of Kerala. Materials and Methods: In this population-based cross-sectional study, 91,628 schoolgoing children between 6 and 17 years of age, from Thrissur district of Kerala were evaluated through school screening programs conducted at the respective schools. Demographic and clinical profiles of refractive errors among children with newly prescribed spectacles were analyzed. Statistical Analysis: Demographic data were represented as bar charts and pie diagrams. Subgroup analysis for type for the influence of age, sex, and rural–urban location on the pattern of refractive error was analyzed using odds ratio. Results: Out of the total 91,628 schoolgoing children, 1079 (1.18%) were newly prescribed with spectacles. Out of these, 549 (50.80%) were boys and 530 (49.20%) were girls. Myopic astigmatism was the most common refractive error (68.30%) in all the age groups taken together and individually. Simple myopia was seen in 13.81%, hypermetropic astigmatism in 13.07%, mixed astigmatism in 3.89%, and simple hypermetropia in 1.20% newly prescribed cases. In the 10–12 year age group, there was a significantly higher chance of occurrence of refractive errors of all types among the rural children in comparison to their urban counterparts. In the 6–9 years' age group, there was a significantly higher chance of occurrence of hypermetropia, hypermetropic astigmatism, and mixed astigmatism among the rural children when compared to the urban children. Conclusion: Prevalence of spectacle use was less than the need for spectacle correction among schoolgoing children in Thrissur district of Kerala. As the prevalence of uncorrected/undercorrected refractive errors was more among the rural upper primary and lower primary school children, targeted strategies to address this deficit in service delivery need to be formulated.

Pattern of wavefront aberrations in Indian children with ametropia

Purpose: The aim of this study was to evaluate the distribution of wavefront aberrations in Indian children with refractive errors and to determine the correlation between the degree of refractive error and aberration. Materials and Methods: A prospective study was conducted on 216 eyes of 108 consecutive children attending the outpatient clinic. Based on refractive error, the children were allocated to five groups: “Emmetropic,” “hyperopic,” “simple astigmatism,” “compound astigmatism,” and “myopic” group. Lower order aberrations (LOAs) and higher order aberrations (HOAs) were analyzed within and between the groups. Results: Mean age of the children was 10.9 years. Of the total 216 eyes, 40 eyes had emmetropia, 52 had simple astigmatism, 54 had compound astigmatism, 43 had myopia, and 27 had hyperopia. In all the groups, increase in spherical equivalent was associated with increase in LOAs of defocus and astigmatism and the root mean square (RMS) of total HOAs. In comparison with the “emmetropic” group, all other groups showed a significant increase in LOAs (P < 0.001) and RMS of total HOAs (P < 0.001), with the “compound astigmatism” group showing higher values. Spherical aberrations were found to be associated with simple astigmatism, compound astigmatism (P = 0.008), and myopia (P = 0.041). Statistical analysis was done using analysis of variance applying Bonferroni correction factor and Pearson's correlation coefficient. Conclusions: Ametropic eyes are associated with HOAs. Indian children were found to have higher values of aberrations when compared to other races. Practitioners may need to factor this while treating children for refractive errors.

Effect of Mitomycin C on Myopic versus Astigmatic Photorefractive Keratectomy.

Purpose. Long-term mitomycin C (MMC) effects on photorefractive keratectomy (PRK) were compared in simple myopic and astigmatic patients. Methods. In this observational cohort study, subjects were selected based on preoperative and postoperative data collected from medical records; they were divided into simple myopia with/without MMC and myopic astigmatism with/without MMC groups. Haze, uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), subjective refraction, and K-reading were evaluated at 1-, 3-, 6-, and 12-month follow-ups. Results. One hundred fifty-nine eyes of 80 subjects (34 women and 46 men; mean age, 26.81 ± 7.74 years; range, 18–53 years; spherical powers, −0.50 to −8.00 DS; and cylindrical powers, −0.25 to −5.00 DC) were enrolled. One year postoperatively, the simple myopia with/without MMC groups showed no difference in UCVA (P = 0.187), BCVA (P = 0.163), or spherical equivalent (P = 0.163) and a significant difference (P = 0.0495) in K-reading; the haze formation difference was nonsignificant (P = 0.056). Astigmatic groups with/without MMC showed a significant difference in K-reading (P < 0.0001). MMC groups had less haze formation (P < 0.0001). Conclusion. PRK with intraoperative MMC application showed excellent visual outcomes. MMC's effect on astigmatic patients was significantly better with acceptable safety and minimal side effects.

Frequency of ocular conditions in native Brazilians from Avaí City, São Paulo State

Abstract Purpose: To perform an epidemiological study of eye diseases in the population of four indigenous communities in the City of Avai in the state of Sao Paulo - Brazil: Ekerua, Kopenoti, Nimuendaju and Teregua. Methods: This is a prospective, cross-sectional, population-based study performed by the Medical Residency Program of the Center of Excellence in Ophthalmology (CEO-Bauru), including all the inhabitants of four indigenous tribes, between the months of March and April 2016. All participants were submitted to a complete eye examination that included refraction test and best-corrected visual acuity, external ocular motility and strabismus, measurement of intraocular pressure (IOP), color vision test, slit lamp examination and a complete evaluation of the fundus. Results: From a total of 584 natives from four villages, 377 (64.55%) attended the project. 283 appointments were performed at CEO - Bauru and 94 evaluations in the health center of Kopenoti village using a mobile ophthalmology unit. 48.54% of the participants were male and 51.46% female. The mean age was 32.03 ± 21.45 years. Our study found prevalence of pterygium of 14.05%, cataract of 6.63%, glaucoma of 1.85% and diabetic retinopathy of 1.59%. These numbers are higher than found in other epidemiological studies. Regarding refractive errors, 36.99% presented astigmatism, 4.24% simple myopia and 8.35% simple hyperopia. Conclusion: These information are extremely important because they show higher rates of eye diseases in a needy and remote population of urban health centers, and in need of medical care. It is noteworthy that all patients from this study who presented refractive errors, received glasses with the corrected refractive lenses.

Effect of homoeopathic preparation of Ruta graveolens on the progression of childhood myopia before, during and after cessation of treatment: A retrospective study

Background: Increased incidence and progression of myopia, especially in Asian countries, have been attributed to excess near work. Topical use of Atropine was effective in controlling myopia but has got side effects and rebound effect after stopping the treatment. Homoeopathy mentions Ruta graveolens (Ruta) for myopia with its action on accommodation. Aim: The aim of the study is to evaluate the effect of Ruta on annual myopia progression rate (AMPR) before, during and after stopping treatment in childhood myopia. Materials and Methods: Ten cases of simple myopia in progressive stage aged 11–16 years were studied retrospectively. Myopia or spherical equivalent of refraction (SER) and AMPR in diopters (D) before treatment were assessed from the previous refraction reports. Ruta 3C was used in BD dose orally for 2 years with a gap of 7 days after every 21 days, and thereafter, treatment was discontinued. Subjective refraction on Snellen's chart at the start, during and after stopping treatment was recorded. From SER values, AMPR at different phases of study was assessed and analysed with paired t-test. Results: Mean AMPR before treatment was −1.10 D (±0.53). After Ruta treatment, there was a significant reduction of −0.27 D (±0.32) in AMPR (t = −4.13, P = 0.003). After stopping the treatment for an average of 10 months, mean AMPR was −0.46 D (±0.49), but this change was insignificant (t = 1.21, P = 0.26). Conclusion: Homoeopathic Ruta 3C was effective in controlling AMPR with no major progression after stopping the treatment.

Frequency of prepapillary vascular loops in Congolese patients

To determine the frequency of prepapillary vascular loops in the population of Congolese patients. We performed a retrospective cross-sectional and descriptive analysis of the data collected between January 2005 and August 2014 from patients diagnosed with prepapillary vascular loops, in an outpatient eye clinic, a general ophthalmology practice. Out of 16,016 patients seen during the study period, 24 patients (27 eyes) were diagnosed with prepapillary vascular loops, for a frequency of 0.15%. The mean age of the patients with prepapillary vascular loops was 37.8 years±14 (SD) (range, 18 to 60 years). Male were more frequently diagnosed with prepapillary vascular loops than female (62.5% vs 37.5%). Unilateral prepapillary vascular loops were found in 77.8% and bilateral in 22.2% of eyes. Most of PPLs were estimated to be arterial (88.9% of eyes) based on clinical observation alone, as fluorescein angiography was not systematically performed. Ophthalmoscopically, the vessels appeared as simple (44.6%) or took more serial turns (corkscew or spiral-shaped) (55.6%). The average length of PPLs was 1.02mm (range 0.6 to 1.5mm) with an orientation (an axis orientation) in the superior nasal sector (50%), inferior nasal sector (33%) and superior temporal sector (17%); and a mean axis of 143° relative to the horizontal. Refractive errors were found in 16 eyes (59.3%) and included simple myopia (4 eyes, 14.8%), myopic astigmatism (8 eyes, 29.6%), hyperopic astigmatism (one eye, 3.7%), hyperopia (3 eyes, 11.1%); One patient (one eye, 3.7%) with high hyperopia had anisometropia. Primary open angle glaucoma was found in 5 (18.5%) eyes; vascular tortuosity was seen in two (7.4%) eyes. No complication such as retinal arterial occlusion, vitreous hemorrhage, or any other complication was found. The frequency of 0.15% found in this study suggests that although rare, prepapillary vascular loops seem to be a bit more common in black people than in white and Asian people. An association between PPLs and refractive errors may be possible.

Relationship between corneal thickness, corneal curvature, and intraocular pressure before and after laser treatment for simple myopia.

To determine the relationship of central corneal thickness (CCT), curvature (CC), and intraocular pressure (IOP) as determinative factors for corneal biomechanics and in refractive surgery. The study investigated 48 eyes from subjects who visited the Excimer Laser Surgery Clinic at the Department of Ophthalmology. The refractive error, IOP, CCT, and CC were measured in all participants. After 3 months, all examinations were repeated. Linear regression demonstrated a significant positive relationship between pre- and postoperative CCT, CC, and IOP values. The IOP showed a significant correlation with CCT (P = 0.033) for pre-PRK, but no significant relationship was seen post-PRK. The CCT also correlated significantly with CC both pre- and post-PRK (P < 0.05). The IOP was significantly correlated with CCT before PRK, but its behavior differed after surgery. Nearly the same correlation was seen between CCT and CC before and after the PRK; nevertheless, IOP measurements should be calculated or estimated more precisely after PRK based on CCT corrections.

Peripapillary Diffuse Chorioretinal Atrophy in Children as a Sign of Eventual Pathologic Myopia in Adults

To search for a morphologic biomarker to differentiate between pathologic myopia and simple childhood myopia. Retrospective case series. The study included children (age ≤15 years) with high myopia (as defined by the Japanese Ministry of Health and Welfare) who attended the High Myopia Clinic between April 1982 and March 1994, had undergone fundus photography, and had a follow-up of 20 years or more. Fundus photographs obtained in childhood and adulthood were examined for presence of pathologic myopia, defined by high myopia (myopic refractive error >8 diopters or axial length ≥26.5 mm) and the presence of stage 2 or higher myopic maculopathy. Myopic maculopathy in childhood. The study included 56 eyes of 29 patients with a mean age of 10.2±3.6 years at the initial visit and an age of 36.0±7.6 years at the last visit. Mean axial length was 27.0±1.4 mm at baseline and 29.7±2.0 mm at the last visit. At the last visit, 19 eyes (34%) had tessellated fundus alone, 31 eyes (55%) had diffuse chorioretinal atrophy, 3 eyes (5%) showed patchy chorioretinal atrophy, and 1 eye (2%) had macular atrophy. Thus, 35 eyes (63%) had pathologic myopia in adulthood. Among the 35 eyes, 29 (83%) already had diffuse chorioretinal atrophy at the initial visit in childhood and the remaining 6 eyes (17%) showed tessellated fundus in childhood. The diffuse chorioretinal atrophy seen in childhood was restricted to the area temporal to the peripapillary region. The presence of peripapillary diffuse chorioretinal atrophy in children with high axial myopia may be an indicator for the eventual development of advanced myopic chorioretinal atrophy in later life. These features in children may be helpful for differentiating simple childhood myopia from eventual pathologic myopia.

Association of Insulin-Like Growth Factor-1 Gene Polymorphisms with Different Types of Myopia in Egyptian Patients.

To investigate the effect of the insulin-like growth factor-1 (IGF-1) gene's rs6214 and rs5742632 polymorphisms on IGF-1 expression levels and their association with different types of myopia in Egyptian patients. A case-control format was used that included 272 patients with myopia and 136 controls. The IGF-1 gene rs6214 and rs5742632 polymorphisms were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analyses. IGF-1 levels were measured by an enzyme-linked immunosorbent assay. In patients with high-grade myopia, the frequencies of the IGF-1 rs6214 GA and AA genotypes, and the A allele were significantly increased compared to the control group: 41.9% vs. 33.8%, 17.7% vs. 8.9%, and 38.9% vs. 25.7%, respectively. Subjects with the GA and AA genotypes and carriers of A allele were significantly more likely to have high-grade myopia: odds ratios (OR) = 1.75, 95% confidence interval (CI) = 1.03-2.9, and p = 0.03; OR = 2.8, 95% CI = 1.3-6.0, and p = 0.003; and OR = 1.8, 95% CI = 1.25-2.61, and p = 0.001, respectively. A nonsignificant association of the IGF-1 gene rs5742632 polymorphism with the two myopia groups was also observed. The IGF-1 levels were significantly increased in patients with high-grade myopia and simple myopia compared to the control group (p < 0.05). In addition, our results showed a nonsignificant association of the IGF-1 (rs6214-rs5742632) haplotype with either simple myopia or high-grade myopia. We found a significant association of the IGF-1 gene rs6214 polymorphism in Egyptian patients with simple myopia and high-grade myopia. IGF-1 levels were significantly increased in relation to the IGF-1 rs6214 genotypes, while a nonsignificant association was found between IGF-1 level and the IGF-1 (rs5742632) genotypes.

Screening for mutation of Decorin gene in simple pathological myopia in Inner Mongolia region

Screening for mutation of Decorin gene in simple pathological myopia in Inner Mongolia region

Comparison of Higher Order Aberrations after Wavefront-guided LASIK and PRK: One Year Follow-Up Results.

Purpose:To evaluate the changes and predictability of higher order aberrations (HOAs) after personalized laser in situ keratomileusis (LASIK) and personalized photorefractive keratectomy (PRK) for simple myopia and compound myopic astigmatism.Methods:In this prospective cross-sectional study, 100 eyes were included. A total of 50 eyes underwent personalized LASIK and 50 eyes underwent personalized PRK. Preoperative and postoperative wavefront data were compared between the two groups. The influential factors and predictability of HOAs were also assessed.Result:Total HOA increased in the amount of 0.01 ± 0.14 μm for the 5 mm pupil (P = 0.55) and 0.08 ± 0.22 μm for the 6 mm pupil (P = 0.02) after PRK; however after LASIK the corresponding values for the 5 and 6 mm pupil sizes were 0.05 ± 0.12 and 0.15 ± 0.18 μm, respectively (P < 0. 001). Mean changes were not significantly different between the PRK and LASIK groups for both 5 and 6 mm pupil sizes (P = 0.21 and P = 0.13, respectively). Spherical aberration increased following LASIK more than following PRK (P < 0.001). Changes in the root mean square (RMS) of total HOA had a statistically significant negative correlation (P < 0.001) with its preoperative value. HOA and spherical aberration reduced in majority of eyes when the preoperative spherical equivalent refraction was low.Conclusion:For the 6mm pupil size, the total HOA increased following both personalized PRK and LASIK with no significant difference between the two groups. Change of the total HOA RMS was influenced by the preoperative values. The known influencing factors could predict nearly 50% of the changes in total HOA.

Amblyopia of refractive origin: a clinical evaluation

Amblyopia is defined as unilateral or bilateral decrease in visual acuity without any organic ocular lesion. It generally develops during the first decade of life when the visual system is vulnerable to deprivation. Unilateral amblyopia is more common than bilateral and the amblyopic eye is called lazy eye. This study was carried out in Faridpur Medical College &amp; Hospital (FMCH) and Diabetic Association Medical College &amp; Hospital (DAMCH) Faridpur, in the department of Ophthalmology from January - 2010 to December 2012 with a view to establish that anisometropic (Refractive) amblyopia is more in patients with astigmatism with the rule of both hypermetropic &amp; myopic types also astigmatism against the rule in hypermetropic patients but simple myopia is not associated with amblyopia. Clinically diagnosed 110 patients of amblyopia of refractive origin were selected. Age of the patients was 6 to 15 years with male &amp; female ratio 1.2:1. There was no pathology in the eyes except refractive error. Refraction done all the cases and found the following results: 26 cases (23.63%) of simple myopic astigmatism with the rule, 19 cases (17.27%) of compound myopic astigmatism with the rule, 10 cases (9.09%) of simple hypermetropia, 38 cases (34.54%) of simple hypermertopic astigmatism with the rule and 17 cases (15.45%) of compound hypermetropic astigmatism againt the rule. No case of simple myopia was associated with amblyopia. Amblyopia was more in patients with astigmatism with the rule of both hypermetropic and myopic types and also astigmatism against the rule in hypermetropic patients but simple myopia was not associated with amblyopia.Faridpur Med. Coll. J. 2014;9(1): 35-36

Functional Amblyopia; A Blinding Disease in a Normal Eye

Amblyopia is reduction of vision with the proper optical correction either in one or both eyes.. The diagnosis of Amblyopia requires both the demonstration of visual acuity loss and the absence of an organic cause. A visual defect screening program was conducted on children aged 3-14 years of Bope-Poddala health unit area of the city of Galle Sri Lanka. Children aged 5-14 years were examined at each respective school. Children aged 3-5 years were examined at the pre schools .Children not attending to pre schools were examined in the community. All possitives and difficult to handle cases with a 10% of normal were referred to the ophthalmology clinic for secondary screening, investigation and diagnosis. Cases of diagnosed Amblyopia were called after one year for re-assessment. A total of 6685 school children and 934 preschool children were enrolled for this study. After exclusion, 5649 children were screened.Out of the total of 5649 children who were screened 439 (7.8%) were found to have eye diseases with or without visual defects giving a prevalence of 78/1000 children. Of those with such diseases, 88.8% had visual defects. The prevalence of visual defect was 6.9% (69/1000 children). Of the children with visual defects 90.0% (351) were due to refractive errors. The prevalence of refractive errors was 6.2% (62/1000 children).The analysis of the prevalence of different types of refractive errors showed that the prevalence of myopic astigmatism was 52.3%, Simple myopia was 24.6%, simple hypermetropia was 12.5%. Myopic astigmatism was the commonest type of refractive error in unilateral or bilateral involvement. The second commonest was simple myopia. It was found that out of 223 children with bilateral refractive errors 11.6% had unilateral Amblyopia and 17.5% had bilateral Amblyopia giving a total of 29.1%. Of all children with unilateral refractive errors 39.8% had Amblyopia. The development of Amblyopia among unilateral refractive errors was higher than bilateral refractive errors (p<0.05).The total prevalence of refractive Amblyopia was 2.1% of the population. Of them 1.4% had unilateral Amblyopia and 0.7% had bilateral Amblyopia. This difference was statistically significant. (P<0.05) Highest prevalence was observed in the age group of six and seven years (3.4% and 3.0%.). Distribution of Amblyopia among males and females were almost equal. The total prevalence of Amblyopia among children was 2.3%. Refractive Amblyopia calculated was 2.1% that consisted of 1.9% of Anisometropic Amblyopia.The strabismic Amblyopia was 0.2%. Deprivation Amblyopia was 0.2%. There were no Amblyopes found in the group of strabismic Amblyopia without refractive errors.

Assessment of biometry and keratometry in low and high degrees of myopia

Purpose: To investigate the possible ocular biometric and keratometric changes in low and high degrees of simple myopia. Subjects of Methods: A sample of 60 myopic subjects their ages between 10 and 30 years recruited from the Makkah Eye Hospital in Khartoum. In this sample, 30 subjects with myopia 6.00 D. Auto keratometry and A-scan biometry were measured from two eyes of each subject. Results: Subjects with high myopia have longer axial length (AL) (P Conclusion: Like previous studies myopia mainly develops with increases in AL of the eye rather than optical changes in cornea or lens.

English

BACKGROUND: Uncorrected refractive errors are a major cause of low vision and even blindness. The refractive errors can be easily diagnosed and corrected by effective screening programmes. The uncorrected refractive errors in children have a definite impact in adversely affecting the learning capacity and scholastic performance. MATERIAL & METHODS: This Cross sectional was conducted from July to December 2013 among 1412 children aged 5-16 years residing in Chandragiri rural area, Chittoor District, Andhra Pradesh. Visual acuity was assessed using Snellen's chart under standard illumination while detailed eye examination among the suspected cases was done by an ophthalmologist including detailed anterior segment evaluation, ocular motility, radioscopy and auto refraction under 2% homatropine cycloplegic refraction. RESULTS: The prevalence of refractive errors was found to be 7.4% among the study children (out of which 6.1% undiagnosed). Simple myopia was found in 2.4% children while astigmatism (both simple and compound combined) was found in around 2.7% children. It was found that the proportion of myopia increased with age being lowest in 5-7 years (0.0%) and highest in 14-16 age group (4.0%). The proportion of astigmatism also was found to be lowest in 5-7 age group (0.0%) and higher in 11-13 age group and 14-16 age group (4.0% each) However, the differences were not statistically significant (P=0.32; NS). The prevalence of myopia was found to be slightly higher in males (2.7%) than in females (2.1%) while that of astigmatism was found to be higher in females (3.1%) than in males (2.3%). However the differences were not statistically significant (P=0.43; NS). A similar prevalence of refractive errors was found in Bangalore and New Delhi while lower and higher prevalence was reported elsewhere. Myopia and astigmatism are the common disorders in several Indian studies including the present study while African studies found myopia to be less common compared to astigmatism and hypermetropia. Many studies including the present study reported an increase in the prevalence of refractive errors with age of the subjects. CONCLUSIONS: A large proportion of refractive errors in children remain undiagnosed. Thus there is tremendous scope for

On-line Pachymetry Outcome of Ablation in Aberration Free Mode TransPRK

There are many independent factors that influence the outcome of refractive surgeries, consisting of patient characteristics and environmental factors. We studied the accuracy of central ablation depth compared to online pachymetry results. A total of 153 eyes that underwent TransPRK at Bina Eye Hospital, Tehran, Iran, were evaluated from November 2010 to January 2012 in a retrospective cross-sectional study. The relevant data were registered and bivariate correlations and linear regression association were investigated statistically. The mean age was 29 ± 5 years. Distribution of refractive errors was as follows: compound myopic astigmatism 123 (80.4%), simple myopia 24 (15.7%), and mixed astigmatism 6 (3.9%). Mean ambient temperature and humidity levels intraoperatively were 23.49 ± 1.16°C and 28.91 ± 6.16%, respectively. There was a significant difference (p<0.001) between the preassumed central ablation depth (131.68 ± 32.72 µm) and the net level of ablation depth (measured by online pachymetry, 168.04 ± 41.47 µm). Temperature and humidity levels were not in any statistically significant correlation with the net amount of difference found. The backward linear regression was done to reveal the association between ablation depth and several variables. This study showed that there is deviation in optical coherence pachymetry online measurements done with SCHWIND AMARIS laser. Ambient temperature and humidity levels intraoperatively do not influence the outcome. However, basic structural characteristics of patients along with change in refractive index and corneal shrinkage because of corneal dehydration are associated with the differences.