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AimTo investigate the heritability of corneal thickness at the apex, entrance pupil centre, thinnest point, pachymetric progression index (PPI) and maximum Ambrósio relational thickness (ARTmax) using Pentacam.MethodsThe present cross-sectional and population-based study was conducted in two rural districts that were selected randomly. Individuals 5 years and older and data from households where one of the parents and at least one child participated in the study were considered for this analysis. All subjects were examined for visual acuity, refraction, biomicroscopy and, finally, Pentacam imaging. The heritability estimate was used to calculate familial aggregation of pachymetric indices.ResultsOf the 3851 selected individuals, 3314 participated in the study. After applying the exclusion criteria, a total of 1383 individuals from 382 households were included in the analysis; of these, 754 (54.52%) were female. The mean age of the subjects was 37.23±19.35 years (from 6 to 93 years). The highest heritability was observed for corneal thickness at the apex (85%), and the lowest was for ARTmax (27.62%). The heritability of other studied parameters, including corneal thickness at the entrance pupil centre, thinnest point and average PPI, was 82.0%, 77.0% and 31.49%, respectively.ConclusionThe high heritability of the mentioned pachymetric parameters confirms the high correlation between these phenotypes and genetic factors and calls for genetic and molecular research to find related genes and to understand the aetiology of associated diseases, especially glaucoma and keratoconus.

Search term Clear input Advanced Help Result Filters Format: Abstract Send to J Glaucoma. 2018 Sep 7. doi: 10.1097/IJG.0000000000001085. [Epub ahead of print] Heritability of Anterior Chamber Indices in Rural Population. Hashemi H1, Yekta A2, Heydarian S3, Ostadimoghaddam H4, Aghamirsalim M5, Derakhshan A6, Khabazkhoob M7. Author information 1 Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran. 2 Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran. 3 Department of rehabilitation science, School of Allied Medical Sciences, Mazandaran University of Medical Sciences, Sari, Iran. 4 Refractive Errors Research Center, Mashhad University of Medical Sciences, Mashhad, Iran. 5 Eye Research Center, Rassoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran. 6 Khatam-al-Anbia Hospital, Mashhad University of Medical Sciences, Mashhad, Iran. 7 Department of Medical Surgical Nursing, School of Nursing and Midwifery, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Abstract OBJECTIVE: To examine the heritability of the anterior chamber depth, angle, and volume as well as the corneal volume and diameter using Pentacam in households living in underserved rural areas of Iran. MATERIALS AND METHODS: This cross-sectional population-based study was conducted in randomly selected households living in two rural districts in the south and north. The data of subjects above 5 years and households in which at least two members (father or mother and a child) had Pentacam data were analyzed. Each subject underwent a comprehensive ophthalmic examination, with emphasis on the measurement of visual acuity and refraction, biomicroscopy, and Pentacam imaging. Heritability was estimated to investigate familial aggregation of anterior chamber indices, and the effects of age, gender, and living area were controlled for as confounding factors. RESULTS: Of the 3851 selected individuals, 3314 participated in the study. After applying the exclusion criteria, the data of 1383 subjects from 382 households were included in the analysis. The mean age of the participants was 37.23±19.35 years (range: 6-93▒y). The highest and lowest heritability estimates were related to the anterior chamber angle (72%) and corneal diameter (28%), respectively. The heritability percentages of the anterior chamber depth, anterior chamber volume, and corneal volume were 47%, 39%, and 57%, respectively. CONCLUSION: The high heritability of the anterior chamber angle points to a high correlation between this phenotype and genetic factors. Further genetic and molecular investigations are suggested to find the related genes and understand the etiology of glaucoma.

Introduction: Cataract is a common cause of vision loss and blindness in humans. After surgical management of cataract, all efforts should be focused on reducing postoperative astigmatism thus providing an excellent vision to patients. Aim: To determine the relationship between corneal incision and refraction changes before and after phacoemulsification surgery in 300 patients undergoing cataract surgery in Khatam hospital in Mashhad, Iran from January 2017 to April 2018. Materials and methods: Three hundred patients (144 women and 156 men) with cataract undergoing phacoemulsification surgery were recruited in this cross-sectional study. Refraction, keratometry and visual acuity measurement were performed before surgery. Then, a steep-based incision in the cornea was made without stitches. A 3.2 mm corneal incision was made at two supratemporal and temporal sites. The patients were followed-up for one and six months, and one year after surgery monitoring their vision and refraction, and performing keratometric measurements. Results: The mean age of the patients was 65.7±9.54 years (age range, 42–84 years). No major complications were observed. The greatest mean of changes in corneal power was in the supratemporal incision (1.28±0.6). Keratometry had a significant relation with the incision (p Conclusions: An incision made along the steepest meridian leads to flatness of this meridian, this effect being more pronounced at the supratemporal incision. A temporal incision is recommended in cases where there is little difference in the keratometry of the two axes.

Purpose: To evaluate the long-term outcomes of collagen crosslinking in early keratoconus. Methods: Thirty eyes of twenty patients with early keratoconus were enrolled. Uncorrected visual acuity (UCVA), best spectacle corrected visual acuity (BSCVA), objective refraction, subjective refraction, corneal topography and pachymetry were assessed before and 3, 6, 12 months and 9 years after performing collagen crosslinking surgery. Results: The patients' mean age was 31.2 ± 5.59 years at nine-year follow-up (range, 25–44 years). The means of preoperative UCVA and BSCVA were 0.57 ± 0.34 and 0.15 ± 0.12 logMAR, respectively, and these values remained stable at the final follow-up (P = 0.990 and P = 0.227, respectively). The mean objective spherical equivalent decreased considerably from –6.00 ± 4.05 D preoperatively to –5.22 ± 3.71 D at the final follow-up (P < 0.05). The mean subjective spherical equivalent was –4.25 ± 2.87 D preoperatively and this value was stable at the last follow-up (P = 0.92). No considerable difference was found between the post- and preoperative mean objective cylinder values (P = 0.34). The mean subjective cylinder value changed significantly from –4.05 ± 1.85 D preoperatively to –3.1 ± 1.42 D at the final follow-up (P < 0.05). The mean central corneal thickness was 496.97 ± 45.95 µm preoperatively and this value was stable at nine-year follow-up (P = 0.183). No significant difference was found between the pre- and postoperative mean maximum and mean minimum corneal curvature values (P = 0.429 and P = 0.248, respectively). There were no significant postoperative complications. Conclusion: Corneal crosslinking in early keratoconus seems to be a safe procedure that can effectively stabilize UCVA, BSCVA, subjective SE and CCT, while improving objective spherical equivalent.

Purpose: The aim of this study was to determine the distribution of corneal eccentricity (E-value) in a normal population and to examine related factors. Methods: In this cross-sectional study, two villages were selected in Iran using multistage cluster sampling. Selected persons were invited to have a comprehensive eye examination. Examinations in each village were performed at a specific location under standard conditions. After testing for vision and refraction and conducting the slit-lamp exam, E-value was measured with Pentacam. Results: Of the 3851 selected individuals, 3314 participated in the study. After applying the exclusion criteria, data from 2610 subjects was used in the analysis for this report. Mean E-value was 0.53 [95% confidence interval (CI): 0.52 to 0.54]. E-value was not significantly different between males and females. Mean E-value reduced with age from 0.60 in subjects aged 6–20 years to 0.47 in subjects older than 70 years. The hyperopic group of participants had significantly lower E-value than myopic and emmetropic ones (P

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.

Purpose To investigate familial aggregation of anterior and posterior corneal curvature, corneal astigmatism, and some corneal topometric indices using the Pentacam. Methods Of 3,851 eligible individuals who resided in the selected areas, 2,779 met the conditions for analysis. However, analysis was limited to families whose Pentacam measures were available for at least 2 family members (father or mother and a child), resulting in 1,383 individuals in 382 families. All selected subjects underwent a set of examinations, including refraction, uncorrected and corrected visual acuity measurement, slitlamp biomicroscopy, and Pentacam imaging. Heritability estimation was used to calculate familial aggregation. Results The results of our study showed a fairly high corneal curvature heritability. The heritability of K2 and K1 in the anterior surface was 58.61% (95% confidence interval [CI], 54.99-62.23) and 55.82% (95% CI, 52.66-58.98), respectively. The heritability of posterior corneal curvature was slightly higher than that of the anterior corneal curvature. The heritability of K2 and K1 in the posterior surface was 63.42% (95% CI, 60.07-66.77) and 59.67% (95% CI, 55.85-63.49), respectively. Investigation of the quantitative topographic corneal indices showed that index of surface variance (ISV), central keratoconus index, and index of vertical asymmetry (IVA) had the highest levels of heritability (81.2% [95% CI, 73.64-88.76], 75.21% [95% CI, 67.19-82.28], and 66.46% [95% CI, 61.99-70.93], respectively). However, keratometric power deviation and index of height asymmetry had the lowest heritability levels (7.48% 95% CI, [4.94-10.02] and 18.31% [95% CI, 16.07-20.55], respectively). Conclusion The familial aggregation and relatively high heritability of the corneal curvature and some keratoconus-related indices, such as ISV and IVA, confirm a high correlation between these phenotypes and genetic factors and warrant further investigation of the genetic mechanisms in keratoconus.

Purpose: This study was performed to assess the learning styles of a sample of Iranian residents through Kolb's and VARK questionnaires. Methods: In this descriptive-analytical study, 45 ophthalmology residents of Mashhad University of Medical Sciences were enrolled. Kolb's and VARK questionnaires were provided, and residents were oriented and guided on how to complete them. Results: Forty-three out of the forty-five ophthalmology residents completed the questionnaire (95.5% response rate). The preferred learning style among ophthalmology residents was assimilative (51.2%), followed by convergent (37.2%), accommodative (7.7%), and divergent (4.7%), based on Kolb's questionnaire. According to the results of the VARK questionnaire, most ophthalmology residents were auditory learners (34.9%), followed by multimodal learners (30.2%). In addition, there was no significant relation between genders, stage of residency, and Kolb's and VARK learning styles (P > 0.05 for all). Conclusion: The most preferred learning styles of ophthalmology residents were assimilative and auditory. Considering the dominant learning styles of learners and incorporating various teaching methods are recommended to enhance the learning among residents.

Purpose The objective of this study was to determine the prevalence of keratoconus and the potential effect of genetic and environmental factors on its prevalence in households living in rural areas of Iran in a large population-based study. Methods The present cross-sectional study was performed in two Iranian rural populations. Two rural areas were randomly selected in the southwest and north of Iran. All individuals over one year of age were invited to participate in the study. The study population underwent a thorough eye examination, including visual acuity measurement, refraction, slit lamp biomicroscopy, and Scheimpflug imaging. The diagnosis of keratoconus was made based on Pentacam-specific criteria, tomographic maps, and clinical findings. After detecting keratoconus cases, its prevalence in the study population was reported as a percentage with a 95% confidence interval (CI). For familial aggregation analysis, the odds ratios of keratoconus and its more severe types were calculated in different family relationships (siblings, parents-offspring, spouses) using second order generalised estimating equation. Results Of the 3851 eligible individuals, 3314 subjects participated in the study. After applying the exclusion criteria, data from 2667 subjects was used in the analysis. The prevalence of keratoconus in the present population was 4% (95% CI: 3-4). The odds of keratoconus were significantly higher in males (OR = 2.30, p = 0.032). To investigate the familial aggregation of keratoconus, we only evaluated families from which at least two members participated in the study. So, 403 families (1452 participants) were evaluated. Our results showed a higher odds ratio for the sibling pairs compare to parent-offspring pairs and as reported, the odds ratio of the spouses was less than 1.0. Conclusion Our findings showed a relatively high prevalence and familial aggregation of keratoconus in rural areas of Iran, independent of age, sex, and place of residence. This aggregation may be due to heredity or the effect of undetermined shared environmental factors.

To evaluate the effects of propofol, etomidate, and thiopental administered during phacoemulsification (PE) cataract extraction on intraocular pressure (IOP) and hemodynamic responses with insertion of laryngeal mask airway (LMA).In a randomized double-blind clinical trial, patients scheduled for PE with general anesthesia were included. Patients were allocated randomly to 3 groups: group 1 (n=34): 0.3 mg/kg etomidate; group 2 (n=33): 2 mg/kg propofol; and group 3 (n=34): 4 mg/kg thiopental. IOP, systolic blood pressure, and heart rate (HR) were measured before induction as a baseline, 2 min after induction (immediately before insertion of LMA), and 1 and 3 min after LMA insertion. Blood pressure (BP) and HR of patients during the surgery were monitored and registered before and after induction and intubation.In 3 groups, IOP decreased significantly after injection of drugs and insertion of LMA in comparison to basic values, although IOP after LMA insertion was more than before LMA insertion. In case of propofol, the changes in IOP between 2 min after induction and the baseline were higher than others, especially thiopental (P=0.031). BP declined remarkably after induction (P0.001) and rose significantly after LMA insertion in all groups, except in the propofol group. The HR was decreased significantly after induction, except in thiopental.Propofol prevented IOP increase after induction compared with other drugs. Decrease in BP and HR after induction and LMA insertion was remarkable. Thiopental seemed to be the best drug for controlling cardiovascular parameters, especially HR, and it also prevents IOP rise.

Purpose To determine the distribution of keratometric indices, corneal thickness, anterior chamber depth, pupil diameter and corneal diameter by Orbscan in a young Iranian population. Methods In this cross-sectional study, samples were selected through multistage cluster sampling from among the students of Mashhad University of Medical Sciences, Iran. After performing refraction and retinoscopy, Orbscan was used for imaging. Results Of 1330 selected students, 1121 participated in the study. After applying the exclusion criteria, final analysis was performed on 1051 subjects. The mean age of the subjects was 26.1±3.2 years (19-34 years old). The mean and 95% confidence interval (CI) of maximum keratometry, minimum keratometry, pupil diameter corneal diameter, anterior chamber depth, and central corneal thickness were 44.5(44.4-44.6), 43.1(43.0-43.2), 4.3(4.3-4.4), 11.7(11.7-11.7), 3.7(3.6-3.7) and 550.5 (548.4-552.6), respectively. After adjusting with age and spherical equivalent (SE), the maximum and minimum keratometry, thinnest corneal thickness were higher in females while the corneal diameter and anterior chamber depth were more in males. Corneal diameter and anterior chamber depth showed significant changes with age. The SE was only correlated significantly with maximum keratometry and anterior chamber depth. Conclusion The results of this study showed the normal ranges and averages of some Orbscan indices in a young Iranian population. The insignificant changes of the corneal diameter and anterior chamber depth with age and the differences between males and females in the evaluated indices should be considered in refractive surgery.

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.

Purpose To evaluate tear film function in patients with diabetes mellitus (DM) using tear film osmolarity (TFO) measurements compared to other tear film function tests. Methods DM patients without any history of ocular surface disorder but with potential effects on the tear film were enrolled in this cross-sectional study. Data including dry eye symptoms, duration of DM, stage of diabetic retinopathy and blood hemoglobin A1c levels were recorded. Tear film break-up time (TBUT) and basic tear secretion (Schirmer test) were assessed. TFO was determined using the Tearlab Osmolarity System. The outcome measures were the difference between the mean values of TBUT, basic tear secretion and TFO in both the study and control groups. Results We recruited 51 DM patients and 20 control subjects with a mean age of 51.2 (range, 21 to 70) and 48.5 (range, 24 to 70) years, respectively. A total of 27 patients (53%) and 11 controls (55%) reported dry eye symptoms (p = 0.668). The mean TBUT was 10.2 ± 4.8 seconds in the study group versus 10.5 ± 2.8 seconds in controls, which was not significantly different (p = 0.747). The mean Schirmer test score was 8.1 ± 4.3 mm in the patients versus 10.1 ± 3.0 mm in the controls (p = 0.069). The mean TFO was 294.1 ± 12.9 mosmol/L in the patients versus 291.4 ± 14.5 mosmol/L in the controls (p = 0.456). It was significantly higher in patients with poor glycemic control determined by hemoglobin A1c > 8% (p = 0.003). TFO had a positive correlation with the duration of DM (p = 0.030) but not with the stage of diabetic retinopathy (p = 0.944). However, TFO showed a significant relationship with dry eye symptoms (p = 0.001). Conclusions TFO is impaired in patients with uncontrolled DM and is better correlated with glycemic control and dry eye symptoms than the TBUT and Schirmer tests.

Purpose To determine the prevalence and risk factors of refractive errors in Iranian university students. Methods In a randomized study, of 424 selected students from the six schools of Mashhad University of Medical Sciences (MUMS), 406 of them participated in the study (response rate: 95.7%). Refractive errors were corrected using auto refraction checked by retinoscopy and subjective refraction. Myopia defined as spherical equivalent (SE) refraction -0.50 dioptre (D) or worse, hyperopia as SE of +0.50D or more, and astigmatism as cylinder –1.0D or worse. Results The prevalence of myopia, hyperopia and astigmatism were 38.4%, 13.8% and 12.8% among the university students respectively. The prevalence of spherical refractive errors were different in males and females (P=0.038). Conclusion The results of this study indicated that nearly two-third of the university students have refractive errors. Myopia appears to be more common among highly educated persons and unversity students are at high risk for it.

Purpose The aim of this study was to determine the prevalence and risk factors of near decompensated heterophoria in a population of university students. Methods In a randomized study, 406 students of six schools of Mashhad University of Medical Sciences were selected and classified into symptomatic and non symptomatic groups. Visual acuity (VA), near point of convergence (NPC), Near point of accommodation (NPA), dissociated and associated phoria, suppression, stereopsis, accommodative facility, relative accommodation, accommodative convergence/accommodation ( AC/A ratio and fusional reserves were measured in two groups. The data were analysed by using SPSS software, version 11.5o. Results The prevalence of symptoms and binocular disorders in students were 41.6% and 21.8% respectively . Of the students,9.1% had near decompensated heterophoria (heterophoria with symptoms). The results of this study showed that VA, NPC, NPA, heterophoria, stereopsis, accommodative facility, relative accommodation, AC/A ratio and fusional reserves were different in symptomatic and asymptomatic subjects and were worsen in students with decompensated heterophoria (P

PURPOSE To determine the prevalence of amblyopia, anisometropia, and strabismus in schoolchildren of Shiraz, Iran. MATERIALS AND METHODS A random cluster sampling was used in a cross-sectional study on schoolchildren in Shiraz. Cycloplegic refraction was performed in elementary and middle school children and high school students had non-cylcoplegic refraction. Uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA) were recorded for each participant. Anisometropia was defined as spherical equivalent (SE) refraction difference 1.00D or more between two eyes. Amblyopia was distinguished as a reduction of BCVA to 20/30 or less in one eye or 2-line interocular optotype acuity differences in the absence of pathological causes. Cover test was performed for investigating of strabismus. RESULTS Mean age of 2638 schoolchildren was 12.5 years (response rate = 86.06%). Prevalence of anisometropia was 2.31% (95% confidence interval [CI], 1.45 to 3.16). 2.29% of schoolchildren (95% CI, 1.46 to 3.14) were amblyopic. The prevalence of amblyopia in boys and girls was 2.32% and 2.26%, respectively (p = 0.945). Anisometropic amblyopia was found in 58.1% of the amblyopic subjects. The strabismus prevalence was 2.02% (95% CI, 1.18 to 2.85). The prevalence of exotropia and esotropia was 1.30% and 0.59%, respectively. CONCLUSIONS Results of this study showed that the prevalence of anisometropia, amblyopia, and strabismus are in the mid range. The etiology of amblyopia was often refractive, mostly astigmatic, and non-strabismic. Exotropia prevalence increased with age and was the most common strabismus type.

Purpose To determine the prevalence and risk factors of refractive errors among schoolchildren in Bojnourd, Iran. Methods In a cross-sectional study using random cluster sampling, 2020 schoolchildren 6 to 17 years of age were selected in this study. The participants totaled 1551; 643 boys and 908 girls of the elementary and middle schoolchildren of Bojnourd, northeast of Iran. Mean age of the participants was 11.2 years (response rate=76.7%). Refractive errors were measured under cycloplegia. Myopia defined as spherical equivalent (SE) refraction - 0.5 dioptre (D) or worse, hyperopia as SE +2.00 D or more, and astigmatism as cylinder -0.75 D or worse. Results The prevalence of myopia, hyperopia and astigmatism were 4.3%, 5.4% and 11.5% respectively and were not related to the gender. The prevalence of myopia and against-the-rule astigmatism increased with age (p

Purpose To determine the prevalence of anisometropia, amblyopia and starbimus in schoolchildren of Bojnourd, Iran. Methods A random cluster sampling was used in a cross-sectional study on 2020 schoolchildren in Bojnourd, northeast of Iran. The participants totaled 1551;643 boys and 908 girls. Mean age of the partipiciants was 11.12 years (respose rate=76.7%). Examinations included: uncorrected and best corrected visual acuity (UCVA and BCVA) measurements, cycloplegic refraction and cover test. Anisometropia defined as spherical equivalent (SE) refraction difference 1.00 D and more between two eyes. Amblyopia was defined as a reduction of BCVA to 20/30 or less in one eye or two lines introcular optotype acuity difference in the absence of pathological causes. Strabismus was characterized as a heterotropia at distance or near fixation. Results The prevalence of anisometropia, amblyopia and strabismus were 2.7%, 2.2 and 2% respectively and were not related to the gender. The prevalence of exotropia, esotropia and hypertropia were 1.37%, 0.51% and 0.12% respectively. Conclusion Prevalence of anisometropia, amblyopia and strabismus among the schoolchildren of Bojnourd were in the mid range and similar to that in most places of the world. Exotropia was the most common strabismus type and comparable to the other Asian countries.

PURPOSE To determine the prevalence of refractive errors in Shiraz schoolchildren by age and gender. METHODS For this cross-sectional study, random cluster sampling was carried out from students of the 2008-2009 academic year. After the initial interview, ophthalmic examinations including tests of visual acuity, non-cycloplegic and cycloplegic refraction and binocular vision were performed. Myopia was defined as a spherical equivalent or =+2.0 D, and astigmatism as a cylinder refraction > or =0.75 D. All values for school grade and gender were directly standardized based on the total student population in the 2008-2009 school year. RESULTS A total of 2130 students were sampled, of which 1872 participated in the study (response rate = 87.88%). The prevalence of uncorrected, best-corrected, presenting and spectacle corrected visual acuity of 6/12 or worse in the better eye was 6.46%, 0%, 1.49% and 0.9%, respectively. The prevalence rates of myopia, hyperopia and astigmatism were 4.35% (95% confidence interval [CI]: 2.89-5.82%), 5.04% (95% CI: 3.50-6.58%), and 11.27% (95% CI: 9.81-12.74%), respectively. Anisometropia was detected in 2.58% of schoolchildren. The prevalence of hyperopia significantly decreased with age (P = 0.021). CONCLUSIONS Compared with other reported rates, the prevalence of myopia in the schoolchildren of Shiraz is similar to that in most places excluding East Asian countries, and that of hyperopia is in the mid range.

To evaluate and compare central corneal thickness measurements using rotating Scheimpflug camera, scanning-slit topography, and ultrasound pachymetry in virgin, healthy corneas.Prospective, observational, cross-sectional study.Central corneal thickness in 157 healthy eyes of 157 patients without ocular abnormalities other than refractive errors was measured, in a sequential order, once with rotating Scheimpflug camera and scanning-slit topography and 3 times with ultrasound pachymetry as the last part of examination. All measurements were performed by a single experienced examiner. The results from scanning-slit topography are given with and without correction for "acoustic correction factor" of 0.92.The average measurements of central corneal thickness by rotating Scheimpflug imaging, scanning-slit pachymetry, and ultrasound were 537.15 ± 32.98 μm, 542.06 ± 39.04 μm, and 544.07 ± 34.75 μm, respectively. The mean differences between modalities were 6.92 μm between rotating Scheimpflug and ultrasound (P.0001), 2.01 μm between corrected scanning-slit and ultrasound (P = .204), and 4.91 μm between corrected scanning-slit and rotating Scheimpflug imaging (P = .001). According to Bland-Altman analysis, highest agreement was between ultrasonic and rotating Scheimpflug pachymetry.In the assessment of normal corneas, rotating Scheimpflug topography measures central corneal thickness values with higher agreement to ultrasound pachymetry.