Wide-field choroidal thickness and vascularity index in myopes and emmetropes.

PURPOSE: To study regional variations in choroidal thickness (CT), luminal thickness and stromal thickness of the choroid, and choroidal vascularity index (CVI) in low myopic and emmetropic eyes using wide-field optical coherence tomography (OCT). METHODS: Sixty-nine healthy young adults between 20 and 38 years of age participated in this study, including 40 low myopes (mean ± SD spherical equivalent (MSE) refractive error: -3.00 ± 1.39 D, range: -6.00 to -0.62 D) and 29 emmetropes (MSE: -0.05 ± 0.09 D, range: -0.25 to +0.12 D). Wide-field CT, luminal thickness, stromal thickness and CVI were measured across five eccentricities (fovea, parafovea, perifovea; near-periphery and periphery) and four quadrants (nasal, temporal, inferior and superior), in vertical and horizontal meridians, while controlling for a range of extraneous factors potentially influencing the CT. Custom-written software was used to segment and binarize the OCT images. RESULTS: Wide-field CT, luminal thickness and stromal thickness, averaged across all participants, exhibited significant topographical variation, with the foveal (379 ± 8 µm, 200 ± 4 µm, 179 ± 4 µm, respectively) and peripheral (275 ± 8 µm, 161 ± 4 µm, 114 ± 4 µm, respectively) regions presenting the thickest and thinnest regions (all p < 0.001). Wide-field CVI showed a progressively higher percentage (greater vascularity) with increasing eccentricity from the fovea towards the periphery (p < 0.001). Macular CT and stromal choroidal thickness were significantly thinner in myopes compared to emmetropes (p < 0.05). Myopes (55.7 ± 0.3%) showed a slightly higher CVI compared with emmetropes (54.4 ± 0.4%) (p < 0.05). CONCLUSIONS: Low myopia in young adults was associated with significant choroidal thinning across the macular, but not extramacular regions, with this decrease in choroidal thickness mostly attributed to thinning in the stromal component of the choroid, rather than the luminal (vascular) component.

Under-correction or full correction of myopia? A meta-analysis

PURPOSE: To compare the effect of full-correction versus under-correction on myopia progression. METHODS: A literature search was performed in PubMed, Scopus, Science Direct, Ovid, Web of Science and Cochrane library. Methodological quality assessment of the literature was evaluated according to the Critical Appraisal Skills Program. Statistical analysis was performed using Comprehensive Meta-Analysis (version 2, Biostat Inc., USA). RESULTS: The present meta-analysis included six studies (two randomized controlled trials [RCTs] and four non-RCTs) with 695 subjects (full-correction group, n = 371; under-correction group, n = 324) aged 6 to 33 years. Using cycloplegic refraction, the pooled difference in mean of myopia progression was - 0.179 D [lower and higher limits: -0.383, 0.025], which was higher but not in full correction group as compared to under correction group (p = 0.085). Regarding studies using non-cycloplegic subjective refraction according to maximum plus for maximum visual acuity, the pooled difference in myopia progression was 0.128 D [lower and higher limits: -0.057, 0.312] higher in under-correction group compared with full-correction group (p = 0.175). Although, difference in myopia progression did not reach significant level in either cycloplegic or non-cycloplegic refraction. CONCLUSIONS: Our findings suggest that, myopic eyes which are fully corrected with non-cycloplegic refraction with maximum plus sphere, are less prone to myopia progression, in comparison to those which were under corrected. However, regarding cycloplegic refraction, further studies are needed to better understand these trends

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Effect of cyclopentolate versus tropicamide on anterior segment angle parameters in three refractive groups.

CLINICAL RELEVANCE: Frequent clinical application of cycloplegia in clinical practice makes it essential to assess how this condition influences anterior segment angle parameters. BACKGROUND: This study aims to compare the effects of cyclopentolate and tropicamide on anterior segment angle parameters in three adult refractive groups. METHODS: Sixty healthy individuals were recruited and assigned into three refractive groups according to inclusion criteria. At baseline visit, anterior segment angle parameters were measured using anterior segment optical coherence tomography in the right eye. All measurements were repeated at two separate visits, one week apart, after administration of tropicamide 1% and cyclopentolate 1% at similar conditions. Main outcome measures were angle-opening distance, trabecular iris angle, trabecular iris space area and anterior chamber depth. Anterior segment angle parameters were recorded at temporal areas (180 degrees). RESULTS: Sixty participants (29 men and 31 women, age: 27.82 ± 4.71-years) completed the experiment. Baseline mean spherical equivalents were +1.52 ± 1.20 D, -0.04 ± 0.33 D and -1.91 ± 0.91-D in hyperopic, emmetropic and myopic groups, respectively. No statistically significant differences were found between tropicamide and cyclopentolate for all angle parameters in three refractive groups. Both drops induced an increase in all parameters in three refractive groups. Analysis between refractive groups revealed that a more hyperopic refraction was associated with less trabecular iris angle, angle-opening distance and anterior chamber depth parameters in baseline, after tropicamide and cyclopentolate instillations. CONCLUSIONS: Topical application of cycloplegic eye drops in healthy individuals leads to small but significant changes in anterior chamber depth and anterior segment angle parameters, regardless of refractive status. Moreover, lower values of anterior chamber depth and anterior segment angle parameters in hyperopic individuals after administration of cycloplegic drops should be taken into account during biometric measurement and phakic intraocular lens implantation. Due to shorter effect and recovery time and less ocular/systemic reaction of tropicamide versus cyclopentolate, tropicamide could be a recommended cycloplegic agent for diagnostic and therapeutic procedures.

Under-correction or full correction of myopia? A meta-analysis.

PURPOSE: To compare the effect of full-correction versus under-correction on myopia progression. METHODS: A literature search was performed in PubMed, Scopus, Science Direct, Ovid, Web of Science and Cochrane library. Methodological quality assessment of the literature was evaluated according to the Critical Appraisal Skills Program. Statistical analysis was performed using Comprehensive Meta-Analysis (version 2, Biostat Inc., USA). RESULTS: The present meta-analysis included six studies (two randomized controlled trials [RCTs] and four non-RCTs) with 695 subjects (full-correction group, n=371; under-correction group, n=324) aged 6 to 33 years. Using cycloplegic refraction, the pooled difference in mean of myopia progression was - 0.179 D [lower and higher limits: -0.383, 0.025], which was higher but not in full correction group as compared to under correction group (p=0.085). Regarding studies using non-cycloplegic subjective refraction according to maximum plus for maximum visual acuity, the pooled difference in myopia progression was 0.128 D [lower and higher limits: -0.057, 0.312] higher in under-correction group compared with full-correction group (p=0.175). Although, difference in myopia progression did not reach significant level in either cycloplegic or non-cycloplegic refraction. CONCLUSIONS: Our findings suggest that, myopic eyes which are fully corrected with non-cycloplegic refraction with maximum plus sphere, are less prone to myopia progression, in comparison to those which were under corrected. However, regarding cycloplegic refraction, further studies are needed to better understand these trends.

Analysis of Age, Gender, and Refractive Error-Related Changes of the Anterior Corneal Surface Parameters Using Oculus Keratograph Topography.

PURPOSE: To assess refractive error, gender, and age-related differences in corneal topography of a normal population with Oculus Keratograph 4. METHODS: This cross-sectional study included a total of 500 normal eyes of 500 individuals with ages ranging from 10 to 70 years. All participants underwent detailed ocular examinations, including visual acuity measurement, slit-lamp examination, and refractive error evaluation. Slit-lamp examination was performed for all individuals to rule out apparent corneal diseases. Corneal topography parameters were assessed using Oculus Keratograph. The data were analyzed based on gender, refractive error, and age groups using independent sample t-test and one-way analysis of variance. RESULTS: Of a total of 500 participants (age: 29.51 ± 11.53 years) recruited for the present study, 66.4% were female, and 33.6% were male. The mean spherical equivalent of refraction was - 0.98 ± 1.65 diopters. Significant differences were noted in steep keratometry (P = 0.035) and corneal astigmatism (P = 0.014) between genders. Assessment of the data based on refractive error revealed significant differences in an index of vertical asymmetry (P < 0.001), index of height asymmetry (P = 0.003), and index of height decentration (P = 0.011). Considering age groups, significant differences were observed in flat keratometry readings (P < 0.001), mean corneal astigmatism (P = 0.02), minimum radius of curvature (P = 0.037), and apex power (P < 0.001). CONCLUSIONS: There was a prominent variation in some topographic parameters based on gender, age, and refractive error. The information on corneal parameters obtained with Oculus Keratograph from normal eyes provides a reference for comparison with diseased corneas.

Comparison of Anterior Chamber Depth between Normal and Keratoconic Eyes: A Systematic Review and Meta-Analysis.

PURPOSE: To review the published data about changes in the anterior chamber depth (ACD) in keratoconus patients. METHODS: In this systematic review and meta-analysis of observational studies, we reviewed the available and relevant literature on anterior segment changes in keratoconic eyes, with a special focus on the ACD, an effective factor in many surgical methods. Articles published up to December 2017 were identified in the following data sources: PubMed, Scopus, Ovid, ISI, ScienceDirect, and Google Scholar. Databases were comprehensively searched using the key words "Anterior Chamber Depth AND Anterior segment AND Keratoconus". RESULTS: A total of 496 studies including these key words were detected. Four hundred fifty-three studies were excluded, and overall 16 studies which precisely described the change in ACD were included in the literature review. The results show that with respect to the applied device, there was a statistically significant difference in ACD between keratoconic eyes and normal eyes except for Galilei analyzer. CONCLUSION: Summarizing the results of studies, this review revealed that ACD is significantly deeper in keratoconic eyes as compared with normal eyes, which could be explained by the steeper corneal curvature.

Pattern visual evoked potential in hypothyroid patients.

PURPOSE: To investigate the functional integrity of visual pathway in hypothyroid patients by pattern visual evoked potential (PVEP). METHODS: We enrolled 36 female patients with history of hypothyroidism (18 overt and 18 subclinical) aged 20 to 60 years and 36 healthy women of similar age (control group). All subjects had a complete ophthalmic examination. For VEP testing, subjects were exposed to checks subtending a visual angle of 15 and 60 min of arc. RESULTS: For the 15 min of arc check size, the mean P100 latency was significantly delayed (113 milliseconds (ms)) and amplitude significantly reduced (9.2 microvolts (µv)) in the hypothyroidism group compared with controls (109.6 ms and 11.6 µv, respectively). For this 15' check size, the group differences were related to significantly increased latency and reduced amplitude of responses in the group with overt hypothyroidism compared with controls. There was no difference between the groups (hypothyroid vs control) with 60 min of arc check size. There was a significant correlation between severity of the disease and PVEP component. CONCLUSIONS: In conclusion, low levels of circulating hypothyroid hormone are associated with delay in the pattern VEP to small check sizes. This CNS involvement worsens in patients with greater severity and duration of hypothyroidism.

Comparison of cyclopentolate versus tropicamide cycloplegia: A systematic review and meta-analysis / Comparación de la cicloplejia con Ciclopentolato y Tropicamida: revisión sistemática y meta-análisis

Purpose: The aim of the present meta-analysis is to compare the efficacy of cyclopentolate and tropicamide in controlling accommodation during refraction. Methods: A comprehensive literature search was performed in PubMed, Scopus, Science direct and Ovid databases by the key words: "tropicamide"; "cyclopentolate"; "cycloplegia" and "cycloplegic" from inception to April 2016. Methodological quality of the literature was evaluated according to the Oxford Center for Evidence Based Medicine and modified Newcastle-Ottawa scale. Statistical analyses were performed using Comprehensive Meta-Analysis (version 2; Biostat Inc., USA). Results: The present meta-analysis included six studies (three randomized controlled trials and three case-control studies). Pooled standardized difference in the mean changes in the refractive error was 0.175 D [lower and upper limits: -0.089; 0.438] more plus in the cyclopentolate group compared to the tropicamide group; however, this difference was not statistically significant (p = 0.194; Cochrane Q value = 171.72 (p < 0.05); I2 = 95.34%). Egger's regression intercept was -5.33 (p = 0.170). Considering type of refractive errors; refractive assessment procedure and age group; although cycloplegic effect of cyclopentolate was stronger than tropicamide; however, this effect was only statistically significant in children; hyperopic patients and with retinoscopy. Conclusion: We suggest that tropicamide may be considered as a viable substitute for cyclopentolate due to its rapid onset of action. Although these results should be used cautiously in infants and in patients with high hyperopia or strabismus when using tropicamide as the sole cycloplegic agent especially in situations that the findings are variable or there is no consistency between the examination results and clinical manifestations of the visual problems

Objetivo: El objetivo del presente meta-análisis es comparar la eficacia de ciclopentolato y tropicamida a la hora de controlar la acomodación durante la refracción. Métodos: Se realizó una búsqueda amplia en la literatura en las bases de datos de PubMed, Scopus, Science direct y Ovid, utilizando las palabras clave: "tropicamida", "ciclopentolato", "cicloplejia" y "ciclopléjico" desde sus inicios a Abril de 2016. La calidad metodológica de la literatura se evaluó con arreglo a Oxford Center for Evidence Based Medicine y la escala Newcastle-Ottawa modificada. Los análisis estadísticos se realizaron utilizando el software Comprehensive Meta-Analysis (versión 2, Biostat Inc., EEUU). Resultados: El presente meta-análisis incluyó seis estudios (tres ensayos controlados aleatorizados y tres estudios de casos-control). La diferencia estandarizada combinada de los cambios medios del error refractivo fue de 0,175 D [límites inferior y superior: -0,089, 0,438], más acusada en el grupo ciclopentolato con respecto al grupo tropicamida aunque, sin embargo, esta diferencia no fue estadísticamente significativa (p = 0,194, Valor Q de Cochrane = 171,72 (p < 0,05), I2 = 95,34%). El valor del intercepto de regresión de Egger fue de -5,33 (p = 0,17). Considerando el tipo de errores refractivos, el procedimiento de valoración refractiva y el grupo de edad, aunque el efecto ciclopléjico de ciclopentolato fue más fuerte que el de tropicamida, dicho efecto fue únicamente significativo en niños, pacientes hipermétropes, y con retinoscopia. Conclusión: Sugerimos la consideración de tropicamida como sustituto viable de ciclopentolato, debido a su rápido inicio de acción. Aunque estos resultados deberían utilizarse con precaución en niños y en pacientes con elevada hipermetropía o estrabismo al utilizar tropicamida como único agente ciclopléjico, especialmente en situaciones en las que los hallazgos sean variables, o no exista consistencia entre los resultados del examen y las manifestaciones clínicas de los problemas visuales

Impact of Vision Therapy on Eye-hand Coordination Skills in Students with Visual Impairment.

PURPOSE: To evaluate the enhancing effects of vision therapy on eye-hand coordination skills in students with visual impairments. METHODS: Thirty-five visually impaired patients who underwent vision therapy comprised the treatment group, and 35 patients with impaired vision who received no treatment comprised the control group. Full ophthalmic examinations were performed, including biomicroscopy, retinoscopy, and assessments of subjective refraction and visual acuity. Eye-hand coordination was evaluated using the Frostig test. Vision therapy in the treatment group was performed using the Bernell-Marsden ball, perceptual-motor pen, random blink test, and random shape assessment. RESULTS: Data were analyzed for the 35 visually impaired patients and 35 control participants. The mean age was 11.51 ± 3.5 and 11.09 ± 3.1 years in the treatment and control groups, respectively. Female participants comprised 80% of the treatment group and 57% of the control group. Before treatment, the mean scores on the Frostig test were 22.74 ± 4.32 and 21.60 ± 4.10 in the treatment and control groups, respectively, and after treatment, the mean Frostig test scores were 24.69 ± 3.99 and 21.89 ± 3.92, respectively. Statistically significant intergroup differences were found in eye-hand coordination (P < 0.05). No significant intergroup differences were noted in the distance and near visual acuity values. CONCLUSION: The results demonstrated that vision therapy could significantly improve eye-hand coordination, but no enhancement was found in near or distance visual acuity.

Distribution of IOP measured with an air puff tonometer in a young population.

PURPOSE: To determine the normal range of intraocular pressure (IOP) in the young and its association with certain corneal parameters using a non-contact device. METHODS: Subjects were selected from students of Mashhad University of Medical Sciences through stratified sampling. All participants had visual acuity testing, corneal imaging, a comprehensive slit-lamp examination by an ophthalmologist, and IOP measurement using a non-contact air-puff tonometer. RESULTS: Of the 1280 invitees, 1073 (83.8%) participated, and 1027 were eligible. Mean IOP was 16.38 mmHg [95% confidence interval (CI): 16.22-16.53] in the total sample, 16.14 mmHg (95% CI: 15.84-16.45) in men, and 16.48 mmHg (95% CI: 16.31-16.66) in women. There was a significant IOP difference between myopes and emmetropes (P = 0.031). Based on the multiple linear regression model, IOP associated directly with age and central corneal thickness (CCT), and inversely with corneal diameter, spherical equivalent (SE), and keratoconus. Based on standardized coefficients of the regression model, CCT and SE had the strongest association with IOP. CONCLUSIONS: In the present study, we demonstrated the IOP distribution in a young population using a non-contact method. CCT and SE were strongly associated with IOP.

Comparison of cyclopentolate versus tropicamide cycloplegia: A systematic review and meta-analysis.

PURPOSE: The aim of the present meta-analysis is to compare the efficacy of cyclopentolate and tropicamide in controlling accommodation during refraction. METHODS: A comprehensive literature search was performed in PubMed, Scopus, Science direct and Ovid databases by the key words: "tropicamide"; "cyclopentolate"; "cycloplegia" and "cycloplegic" from inception to April 2016. Methodological quality of the literature was evaluated according to the Oxford Center for Evidence Based Medicine and modified Newcastle-Ottawa scale. Statistical analyses were performed using Comprehensive Meta-Analysis (version 2; Biostat Inc., USA). RESULTS: The present meta-analysis included six studies (three randomized controlled trials and three case-control studies). Pooled standardized difference in the mean changes in the refractive error was 0.175 D [lower and upper limits: -0.089; 0.438] more plus in the cyclopentolate group compared to the tropicamide group; however, this difference was not statistically significant (p=0.194; Cochrane Q value=171.72 (p<0.05); I2=95.34%). Egger's regression intercept was -5.33 (p=0.170). Considering type of refractive errors; refractive assessment procedure and age group; although cycloplegic effect of cyclopentolate was stronger than tropicamide; however, this effect was only statistically significant in children; hyperopic patients and with retinoscopy. CONCLUSION: We suggest that tropicamide may be considered as a viable substitute for cyclopentolate due to its rapid onset of action. Although these results should be used cautiously in infants and in patients with high hyperopia or strabismus when using tropicamide as the sole cycloplegic agent especially in situations that the findings are variable or there is no consistency between the examination results and clinical manifestations of the visual problems.

Part-time versus full-time occlusion therapy for treatment of amblyopia: A meta-analysis.

PURPOSE: To compare full-time occlusion (FTO) and part-time occlusion (PTO) therapy in the treatment of amblyopia, with the secondary aim of evaluating the minimum number of hours of part-time patching required for maximal effect from occlusion. METHODS: A literature search was performed in PubMed, Scopus, Science Direct, Ovid, Web of Science and Cochrane library. Methodological quality of the literature was evaluated according to the Oxford Center for Evidence Based Medicine and modified Newcastle-Ottawa scale. Statistical analyses were performed using Comprehensive Meta-Analysis (version 2, Biostat Inc., USA). RESULTS: The present meta-analysis included six studies [three randomized controlled trials (RCTs) and three non-RCTs]. Pooled standardized difference in the mean changes in the visual acuity was 0.337 [lower and upper limits: -0.009, 0.683] higher in the FTO as compared to the PTO group; however, this difference was not statistically significant (P = 0.056, Cochrane Q value = 20.4 (P = 0.001), I2 = 75.49%). Egger's regression intercept was 5.46 (P = 0.04). The pooled standardized difference in means of visual acuity changes was 1.097 [lower and upper limits: 0.68, 1.513] higher in the FTO arm (P < 0.001), and 0.7 [lower and upper limits: 0.315, 1.085] higher in the PTO arm (P < 0.001) compared to PTO less than two hours. CONCLUSIONS: This meta-analysis shows no statistically significant difference between PTO and FTO in treatment of amblyopia. However, our results suggest that the minimum effective PTO duration, to observe maximal improvement in visual acuity is six hours per day.

The distribution of orbscan indices in young population.

PURPOSE: To determine the distribution of anterior eye biometry indices, such as keratometry pachymetry, anterior chamber depth (ACD), pupil diameter, and corneal diameter, as measured by Orbscan instrument in a young Iranian population. METHODS: A cross-sectional study was conducted, and subjects were selected through multistage cluster sampling from the students of Mashhad University of Medical Sciences. Objective and subjective refraction were performed followed by Orbscan imaging. RESULTS: A total of 1330 subjects were selected, 1121 of which participated in the study. After applying the exclusion criteria, the final analysis was performed on the data of 1051 subjects. The mean age of the participants was 26.1 ± 3.2 years (19-34 years old). The mean ± SD and 95% confidence interval (CI) of maximum keratometry, minimum keratometry, pupil diameter, corneal diameter, ACD, and central corneal thickness was 44.5 ± 1.7 (44.4-44.6), 43.1 ± 1.6 (43.0-43.2), 4.3 ± 0.9 (4.3-4.4), 11.7 ± 0.4 (11.7-11.7), 3.7 ± 0.3 (3.6-3.7), and 550.5 ± 35 (548.4-552.6), respectively. After adjusting for age and the mean spherical equivalent (MSE), maximum keratometry, minimum keratometry, central corneal thickness, and the thinnest pachymetry were statistically significantly higher in female subjects (P < 0.001) whilst the corneal diameter and ACD were higher in male subjects (P < 0.001). The pupil diameter and ACD showed statistically significant changes with age (P < 0.001). The MSE was only correlated with maximum keratometry and ACD (P < 0.001). CONCLUSION: In this study, the distribution of Orbscan measurements for the anterior segment parameters was reported in a large sample of the young Iranian population. Age, gender, and refractive error may affect the orbscan measurements.

Amplitude of accommodation in an 11- to 17-year-old Iranian population.

PURPOSE: The aim was to determine normal values of accommodative amplitude (AA) during adolescence in Iran. METHODS: In this cross-sectional study, sampling was done from high school students in Kermanshah in 2015 through a multi-stage cluster sampling method and selected students were invited to participate in the study. Examinations were performed on-site at each sampled high school. All students had visual acuity and refractive examination followed by measurement of AA. Accommodative amplitude was tested with Donder's push-up method using a Royal Air Force (RAF) near point rule. RESULTS: Of the 1,070 selected students, 901 were included in the study and their mean age was 14.4 ± 1.7 years. Mean AA in this study was 11.53 ± 3.02 D (range: 5.00-28.50 D). Mean AA was 15.33 D in 11-year-olds and significantly decreased with age, until it reached 10.40 D in the 17-year-old age group. Mean AA in boys and girls were 10.09 ± 2.48 D and 11.65 ± 3.03 D, respectively. Based on the multiple linear regression model, younger age (coefficient = -0.774) and female gender (coefficient = 1.060) significantly associated with AA. CONCLUSION: This study showed that the AA in Iranian teenagers is lower than that calculated with Hofstetter's formula. It is important to take account of this point when making diagnostic and therapeutic decisions.

Topographic determination of corneal asphericity as a function of age, gender, and refractive error.

The aim of the study is to evaluate corneal asphericity in three diameters of 5, 6, and 7 mm, and to assess the effect of age, refractive error, and gender on asphericity. The study included 500 healthy subjects with a mean ± SD age of 29.51 ± 11.53 years. All analyses were based on the right eyes of the patients. Topographic data were analyzed using Oculus Keratograph 4. Mean ± SD corneal asphericity values of the study population in 5, 6, and 7 mm diameters were -0.21 ± 0.11, -0.24 ± 0.10, and -0.27 ± 0.11, respectively. The anterior corneal surface asphericity showed no correlation with either age, gender, or refractive error. The corneal asphericity shows a tendency for an increase with diameter and asphericity does not have a significant correlation with any factors of age, gender, and refractive error.

Evaluating Three Different Methods of Determining Addition in Presbyopia.

PURPOSE: To compare three different methods for determining addition in presbyopes. METHODS: The study included 81 subjects with presbyopia who aged 40-70 years. Reading addition values were measured using 3 approaches including the amplitude of accommodation (AA), dynamic retinoscopy (DR), and increasing plus lens (IPL). RESULTS: IPL overestimated reading addition relative to other methods. Mean near addition obtained by AA, DR and IPL were 1.31, 1.68 and 1.77, respectively. Our results showed that IPL method could provide 20/20 vision at near in the majority of presbyopic subjects (63.4%). CONCLUSION: The results were approximately the same for 3 methods and provided comparable final addition; however, mean near additions were higher with increasing plus lens compared with the other two methods. In presbyopic individuals, increasing plus lens is recommended as the least time-consuming method with the range of ±0.50 diopter at the 40 cm working distance.

Pentacam top indices for diagnosing subclinical and definite keratoconus.

PURPOSE: To determine pachymetric, aberrometric, and topometric indices in patients with definite and subclinical keratoconus and the validity of these indices in the diagnosis of keratoconus. METHODS: We evaluated 262 keratoconic and 97 healthy eyes in this study. Pentacam HR examination was performed for all participants, and the data of all pachymetric, aberrometric, and topometric indices was extracted for the study population. RESULTS: The average of all evaluated pachymetric and topometric indices and the 3rd and 5th order vertical coma aberrations showed a significant difference between the study groups (p < 0.001). Belin/Ambrosio Deviation Display (BAD_D), Index of Vertical Asymmetry (IVA), Index of Surface Variance (ISV), and 5th order vertical coma aberration were identified as the best diagnostic criteria for the diagnosis of subclinical keratoconus (R (2) = 0.65, p <0.001), and BAD_D, mean keratometry and 3rd order vertical coma aberration were identified as the best diagnostic criteria for the diagnosis of definite keratoconus (R (2) = 0.91, p <0.001). The sensitivity and specificity of the above-mentioned models were 83.6% and 96.9%, and 97.9% and 96.9%, respectively. CONCLUSION: Simultaneous evaluation of BAD_D, 5th order vertical coma aberration, IVA, and ISV, especially when the pattern of the corneal curvature is normal, can detect subclinical keratoconus with high sensitivity and specificity. As for definite keratoconus, each of the BAD_D, mean keratometry, and 3rd order vertical coma aberration indices has a desirable diagnostic validity. However, the aforementioned indices do not negate the importance of widely recognized and acceptable indices like keratometry and central corneal thickness.

The prevalence of refractive errors in 6- to 15-year-old schoolchildren in Dezful, Iran.

PURPOSE: To determine the prevalence of refractive errors, among 6- to 15-year-old schoolchildren in the city of Dezful in western Iran. METHODS: In this cross-sectional study, 1375 Dezful schoolchildren were selected through multistage cluster sampling. After obtaining written consent, participants had uncorrected and corrected visual acuity tests and cycloplegic refraction at the school site. Refractive errors were defined as myopia [spherical equivalent (SE) -0.5 diopter (D)], hyperopia (SE ≥ 2.0D), and astigmatism (cylinder error > 0.5D). RESULTS: 1151 (83.7%) schoolchildren participated in the study. Of these, 1130 completed their examinations. 21 individuals were excluded because of poor cooperation and contraindication for cycloplegic refraction. Prevalence of myopia, hyperopia, and astigmatism were 14.9% (95% confidence interval (CI): 10.1-19.6), 12.9% (95% CI: 7.2-18.6), and 45.3% (95% CI: 40.3-50.3), respectively. Multiple logistic regression analysis showed an age-related increase in myopia prevalence (p << 0.001) and a decrease in hyperopia prevalence (p << 0.001). There was a higher prevalence of myopia in boys (p<<0.001) and hyperopia in girls (p = 0.007). CONCLUSION: This study showed a considerably high prevalence of refractive errors among the Iranian population of schoolchildren in Dezful in the west of Iran. The prevalence of myopia is considerably high compared to previous studies in Iran and increases with age.

The prevalence of keratoconus in a young population in Mashhad, Iran.

PURPOSE: To determine the prevalence of keratoconus and some associated factors in the students of Mashhad University of Medical Sciences, Iran. METHOD: In this cross sectional study, multistage cluster sampling was used to select the participants. All participants underwent retinoscopy, slit lamp examination, topography with the TMS-4 and corneal assessment with the Orbscan II. The diagnosis of keratoconus was based on both clinical evidence and the results of corneal imaging. RESULTS: Of 1280 selected students, 1073 agreed to participate in the study, and of those who agreed, 1027 fulfilled the inclusion criteria. 42.5% of the study population was male with a mean age of 26.1 ± 2.3 years. The prevalence of keratoconus was 2.5% (n = 26) (95% confidence interval, CI 1.6-3.5). Eighteen students (69%) had bilateral keratoconus. Imaging of the cornea revealed that 70% of the keratoconics had nipple cones and the remaining had asymmetric bow-tie patterns. The prevalence of keratoconus was not significantly associated with age or gender (p > 0.05). In a multiple logistic regression model, family history (OR = 11.4, 95% CI: 2.5-51.3) and eye rubbing (OR = 6.3, 95% CI: 1.6-24.3) were significantly correlated with keratoconus. CONCLUSIONS: These results taken together with recent studies in the area suggest that keratoconus may have a higher prevalence in the Middle East and Asia than in Western Countries.