Background:  Some studies have shown that eyes undergo a hyperopic shift after the presbyopia, whereas others have reported a myopic shift. Objective: The purpose of this study was to determine types and the degree of Refractive errors before and after presbyopia. Methods: This was a cross sectional study carried out at the department of optometry (Mashhad University of Medical Sciences) in 2001. Following routine optometric examination, the type and degree of Refractive errors of 500 patients before and after presbyopia were statically analyzed using X2 and student t-tests. Findings:  The prevalence of hyperopia was 19.4% before presbyopia which later increased to 40.1% (p<0.001). Following the occurrence of presbyopia, against-the-rule astigmatism increased to 12.3% whereas the with-the-rule astigmatism decreased to 12.9% (p<0.001). The distribution of oblique astigmatism was 3.7% and 3.4%before and after presbyopia, respectively. The gender had no effect on Refractive errors before and after presbyopia. Conclusion: The presbyopia caused a reduction in optical power of eyes and also increased hyperopia. Reduced rigidity of the upper tarsal plate associated with presbyopia, caused an increase in the against-the-rule astigmatism.    

Purpose: To determine the effect of carpet weaving on Refractive errorsMethods: In this cross sectional study, carpet weavers and non-weavers in the normal population of Mashhad were regarded as exposed and non-exposed groups, respectively. A carpet weaver was a person who wove carpets 7 hours a day for at least 2 years. The non-weavers group was selected from the population of Mashhad through stratified cluster sampling. The variables of age, gender, education, with respect to their frequency, were matched between the two groups.Results: In this study, 266 carpet weavers (exposed individuals) and 549 non-weavers group (non-exposed individuals) were evaluated. The prevalence of myopia was 78.9% in carpet weavers and 19.0% in non-weavers [Odds ratio (OR)=16.03, 95% confidence interval (CI)=11.13-23.09]. The prevalence of hyperopia was 6.02% in carpet weavers, and 56.75% in non-weaver group (OR=0.05, P<0.001). The prevalence of astigmatism was 39.47% in carpet weavers and 21.46% in non-weavers. The odds of against-the-rule (ATR) astigmatism was 1.72 times more in carpet weavers as compared to non-weavers (P<0.001).Conclusion: The results of this study showed that carpet weaving had a strong correlation with myopia. In addition to myopia, the prevalence of astigmatism, specially ATR astigmatism, was higher in carpet weavers.

Background and Objectives: Autorefractometer is usually used in every eye clinic. Clinical retinoscopy and Jackson cross cylinder refinement are very accurate methods for measurement of Refractive errors. The aim of this study was to evaluate accuracy of autorefractor Topcon RM-A2000 for measurement of Refractive errors.Materials and Methods: In a prospective study of Refractive errors, a total of 300 patients, between 5-75 years old, underwent clinical retinoscopy, Jackson cross cylinder refinement and Refractive error measurement with Topcon RM-A2000 autorefractometer for both the eyes. Sphere, cylinderical power and cylindrical axis examined by of autorefractometry were compared with the findings observed with clinical retinoscopy and Jackson cross cylinder refinement.Results: In our study, myopic shift was observed in eyes of all patients on autorefractometry due to instrument myopia.Conclusion: It is concluded that autorefractometry is an instrument for Refractive error estimation and the results should be refined before spectacle prescription.

Purpose: To evaluate the role of active uveitis on Refractive errors changes.Methods: A Cohort single group study was conducted on patients with acute or recurrent uveitis. Cyclorefraction was performed in both phases of active and quiescent. Sphere, cylinder and sphere equivalent power were compared in active and quiescent phases and analyzed statistically.Results: Sixty-six patients (eighty-eight eyes) were enrolled in this study. Mean age was 34 ± 14 years (range 6 to 65). 61.7% of the patients were women (54 out of 88). Among the 46 cases of anterior uveitis 25 eyes (54%) were in acute and 21 eyes (46%) were in recurrent phase. Spherical power changes were statistically significant in anterior non-granolumatous uveitis (P=0.039) and intermediate uveitis (P=0.00 2). Spherical equivalent power changes were statistically significant different in intermediate uveitis (P=0.005) and panuveitis (P=0.096) groups. Cylinder power did not show any significant changes in none of the above mentioned groups. This study showed that, in anterior non-granolumatous uveitis and panuveitis, spherical and spherical equivalent power changes were shifted toward myopia during active uveitis and just spherical power changes were shifted toward hyperopia in intermediate uveitis. Regression analysis disclosed that only activity of uveitis and age had a statistically significant effect on the spherical power changes after adjustment (P<0.001 and P=0.0 36, respectively). Evaluating spherical equivalent power changes, regression analysis showed that activity of uveitis and anatomic location of uveitis had a statistically significant effect (P=0.00 3 and P=0.00 1, respectively).Conclusion: Active uveitis plays an effective role on changing the Refractive powers. The shift of these changes depends on the inflammated anatomical area; in anterior uveitis it is toward myopia and in intermediate uveitis it is toward hyperopia.

Background and Aim: As Refractive errors are the most common ocular disorders, which are usually corrected with eye-glasses and the clients' satisfaction is of general and global significance in the modern world, this study was intended to cross-sectionally describe and analyze the intensity of Refractive errors and the satisfaction of people suffering from Refractive errors about glasses prescribed for them to correct their errors.Materials and Methods: The subjects of the study were 150 patients with Refractive errors. The study data were collected through (1) interview checklist to record the demographic details of the patients and the satisfaction of the patient and the person who accompanied him/her and (2) observation and examination checklists to determine the type and intensity of Refractive errors.Results: 34.7% of the subjects were male and the rest female. Their mean age was 29.06±14.57; 63.8% of the patients and 67.2% of their mates were dissatisfied with glasses. The most common Refractive disorders in descending order were myopia, astigmatism and hyperopia. No significant relationships were found to exist between myopia, factors such as sex and job with dissatisfaction from eyeglasses. However, a significant relationship was observed between age groups and satisfaction from eyeglasses (P<0.01).Conclusion: In order to gain the satisfaction of the people using eyeglasses, contact lenses and surgical procedures which are associated with advantages and disadvantages, to correct for Refractive errors a number of factors including medical diagnosis, the patients’ attitude and socioeconomic status, and the dominant social culture, are to be taken into consideration.