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PurposeTo assess the diagnostic power of the Corneal Visualization Scheimpflug Technology (Corvis ST) provided corneal biomechanical parameters in keratoconic corneas.MethodsThe following biomechanical parameters of 48 keratoconic eyes were compared with the corresponding ones in 50 normal eyes: time of the first applanation and time from start to the second applanation [applanation-1 time (A1T) and applanation-2 time (A2T)], time of the highest corneal displacement [highest concavity time (HCT)], magnitude of the displacement [highest concavity deformation amplitude (HCDA)], the length of the flattened segment in the applanations [first applanation length (A1L) and second applanation length (A2L)], velocity of corneal movement during applanations [applanation-1 velocity (A1V) and applanation-2 velocity (A2V)], distance between bending points of the cornea at the highest concavity [highest concavity peak distance (HCPD)], central concave curvature at the highest concavity [highest concavity radius (HCR)]. To assess the change of parameters by disease severity, the keratoconus group was divided into two subgroups, and their biomechanical parameters were compared with each other and with normal group. The parameters' predictive ability was assessed by receiver operating characteristic (ROC) curves. To control the effect of central corneal thickness (CCT) difference between the two groups, two subgroups with similar CCT were selected, and the analyses were repeated.ResultsOf the 10 parameters compared, the means of the 8 were significantly different between groups (P < 0.05). Means of the parameters did not show significant difference between keratoconus subgroups (P > 0.05). ROC curve analyses showed excellent distinguishing ability for A1T and HCR [area under the curve (AUC) > 0.9], and good distinguishing ability for A2T, A2V, and HCDA (0.9 > AUC > 0.7). A1T reading was able to correctly identify at least 93% of eyes with keratoconus (cut-off point 7.03). In two CCT matched subgroups, A1T showed an excellent distinguishing ability again.ConclusionsThe A1T seems a valuable parameter in the diagnosis of keratoconic eyes. It showed excellent diagnostic ability even when controlled for CCT. None of the parameters were reliable index for keratoconus staging.

Purpose: The aim was to determine the prevalence of myopia and hyperopia and related factors in underserved rural areas in Iran. Methods: Under random cluster sampling, two rural regions were randomly selected in the north and southwest of the country, and 3,061 persons over 15 years of age were invited into the study. After selecting samples, all participants had refraction, measurement of uncorrected vision and visual acuity and ocular health examination by slitlamp biomicroscopy. Results: Of the 3,061 invitees, 2,575 participated in the study (response rate: 84.1 per cent). After excluding those who met the exclusion criteria or had missing refractive data, eventually there were 2,518 subjects available for this analysis. The mean age of the participants was 44.3 AE 17.5 years (range: 16 to 93 years) and 1,460 of them (58.0 per cent) were female. The overall prevalence of myopia and hyperopia in this study was 25.2 per cent (95 per cent CI: 23.2 to 27.2) and 22.5 per cent (95 per cent CI: 20.6 to 24.4), respectively. The prevalence of myopia increased from 20.9 per cent in participants 16 to 20 years to 32.9 per cent in the 21 to 30 years age group, declined up to the age of 60 years and increased again afterwards. The lowest prevalence was 6.8 per cent observed in the 16 to 20 years age group and the highest was 45.8 per cent in 61-to 70-year-olds. In the final logistic regression model, myopia significantly associated with age, higher education levels and cataracts, while hyperopia associated with age, lower education levels and male gender. Conclusion: In our study, the prevalence of myopia was lower and the prevalence of hyperopia was higher compared to most previous studies. The findings of this study imply that refractive errors vary by age. Compared to urban populations, rural dwellers of the same region have more children and especially elderly people, weaker economic status and less access to health-care services. 15All the above mentioned issues can impact the health status of rural dwellers. The present study examines the prevalence of refractive errors and their associated factors in age groups over 15 years old in underserved rural areas in Iran. MATERIALS AND METHODSThis cross-sectional study was conducted through a multistage cluster sampling approach in Iran in 2015. The target population was the residents of underprivileged villages over 15 years old in two randomly selected districts in the north and southwest of the country. The sampling frame was based on a roster of deprived areas provided by the Presidential Office of Rural Development. Selected districts were Shahyoun in the southwest (a district of Dezful County, Khuzestan Province) and Kajour in the north (a district of Noshhar County, Mazandaran Province). Then, a number of villages were randomly selected from a roster of all villages in these two districts. To ensure that the sample size in each district was proportionate to their total population, 15 villages were sampled in Shahyoun and five in Kajour, because Shahyoun has smaller...

PurposeTo determine the short-term effect of rigid gas permeable (RGP) contact lenses on corneal aberrations in keratoconic patients.MethodSixteen keratoconic eyes with no history of RGP lens wear were included. They all had corneal aberrometry using Pentacam, and different aberration indices of the anterior and posterior surfaces of the cornea were measured before and 3 months after fitting RGP lenses. The effect of baseline parameters on these changes was tested in univariate and multiple models.ResultsTotal aberrations and individual Zernike coefficients did not show statistically significant changes after using RGP lenses. Although not statistically significant, vertical coma decreased in the anterior (p = 0.073) and posterior surface (p = 0.095). Relationships that remained statistically significant in the multiple model were between baseline central corneal thickness and changes in total higher order aberrations and anterior 4th order astigmatism 0°, and between baseline 2nd order astigmatism 45° and its changes.ConclusionIn this study, corneal aberrations remained unchanged 3 months after wearing RGP contact lens. Further studies with sufficient samples in different groups of keratoconus severity or baseline aberrations are needed to obtain more accurate results.

PurposeTo determine the distribution of iris color and its relationship with some ocular diseases in a rural population of Iran.MethodsTwo rural areas of the north and southwest of Iran were selected by a cross-sectional study using multi-stage cluster sampling. After selecting samples, the participants had an eye examination including measuring visual acuity, refraction, and Pentacam imaging. Then an eye examination for individuals was performed by slit-lamp.ResultsOut of 3851 invited people, 3314 participated in this study (participation rate, 86.05%). Dark brown [41.28%, confidence interval (CI) 95% = 31.88–50.68] and blue (0.99%, CI 95% = 0.57–1.41) were the most and the least type of iris colors among participants of this study. Compared to others, people with a dark iris have the biggest anterior chamber depth (ACD), angle and volume while central corneal thickness (CCT), keratometry and pupil were highest among people with a dark brown iris (P < 0.002). Considering the dark brown group as a base group, the chances of being afflicted to cataract among people with dark, light brown, green, and blue irises are 1.89 (CI 95% = 1.25–2.86), 1.53 (CI 95% = 1.17–2.01), 4.60 (CI 95% = 2.17–9.71), and 12.17 (CI 95% = 5.05–29.31), respectively. The chance of being afflicted to myopia among people with green irises and to hyperopia among people with blue irises were high (1.60, CI 95% = 1.08–2.36 and 3.20, CI 95% = 1.03–9.97, respectively).ConclusionsDark brown was the most prevalent iris color in rural areas of Iran. The index of cornea among people with dark and dark brown iris color is higher than other people, and people with light iris color are at a higher risk of developing eye disease such as cataract, corneal opacity, and refractive error. To determine this relationship and its usage for therapeutic and public health purposes, further studies are recommended.