Background: The methods of ammetropia of human eye correction are divided into invasive and non invasive methods. Each method has its own advantages and disadvantages. Each method has limitations due to the type of compensation; therefore it is difficult to make a straight forward decision. In this study we tried to compare the results of methods to find out their predictability, Uncorrected Visual Acuity, safety and stability.Methods: We investigated data of 24012 patients of different operation types in published papers by using the following keywords: Conductive Keratoplasty (CK), Hyperopic Thermokeratoplasty (HTK), Diode Laser Thermal Keratoplasty (DTK), Laser Thermal Keratoplasty (LTK), Photorefractive Keratectomy (PRK), Laser in Situ Keratomileusis (LASIK), Laser SubEpithelial Keratomileusis (LASEK).The criteria for selection of papers were safety, predictability, stability and uncorrected visual acuity. Data were analyzed with Chi-square test.Conclusion: For those patients with hypermetropia less than 3.5 diopter, CK and LTK have best correction results, respectively. Then the results of PRK and LASEK were the same. For all range of myopia, LASEK provided the best results and then LASIK was proper for moderate and higher myopia refractive errors, and PRK was useful in low myopia refractive anomalies.

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.

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.    

Background and Objective: Intermittent exotropia is the most common type of outward deviation of the eye in childhood. The association between myopia refractive error and intermittent exotropia has been shown in very few studies. This study was conducted to investigate the association between various refractive errors and the course of their changes in patients with intermittent exotropia. Methods: This retrospective study was conducted on 130 patients with intermittent exotropia younger than 16 years of age who referred to Khatam-al-Anbia Eye Hospital in Mashhad. The records of patients with follow-up were reviewed in terms of age, gender, and near and distance angles of deviation using cover test, type and grade of refractive errors at the initial visit and subsequent visits using cycloplegic drops, types of treatments performed, and dominance of the patients' eyes. Changes in refractive errors during different visits in the patients were examined and compared. Findings: The mean age of the patients was 5.64±4.08 years, of which 77 (59.2%) were girls. The mean distance deviation angle of the patients was 30.79±12.13 prism diopters and the mean near deviation angle was 24.27±17.85 prism diopters. The most common treatment performed for the patients was patch therapy (57.4%). At the initial visit, 77 patients (54%) were hyperopic. In the non-dominant eye, changes in refractive errors towards a decrease in spherical refraction were significant (p=0.002). Conclusion: The results of this study showed that most patients were hyperopic and the course of changes was towards a decrease in spherical equivalent (shift towards myopia).

Objectives: The eye refractive errors, including myopia, hyperopia, and astigmatism, are the most important visual impairments worldwide. Based on the existing evidence suggests, the visual impairment could contribute to falling in the elderly. Therefore, this study aimed to determine the influence of vision impairment of older adults with eye refractive errors on the occurrence of falls and postural control.Methods & Materials: The older people referred to the health center of the 9th district of Tehran municipality for ophthalmic examination were examined (using ophthalmoscope and Snellen chart) by skilled ophthalmologists. Then, certain information such as their age, sex, history of special eye disease or operation, history of fall during the last 12 months, etc. was gathered through questionnaires from the older people who accepted to participate in this study after giving their informed consents. Based on eye screening results, 77 older adults with refractive errors of hyperopia (n=19, mean [SD] age=67 [5.85] y); astigmatism (n=22, mean [SD] age=70.32 [5.60] y); and both hyperopia and astigmatism (n=36, mean [SD] age=69.78 [7.69] y), as well as 23 older healthy adults, mean (SD) age=70.29 (5.29) y, without any obvious eye disorders were enrolled in this study. Their history of falls and postural control were evaluated. The postural control was determined using the Timed Up and Go (TUG) test. The statistical tests were analysis of variance (ANOVA) for comparing the groups with regard to postural control and the Chi-square test for comparing the prevalence of falls between groups with refractive errors and the healthy group.Results: The studied subjects comprised 23% (n=23) healthy ones, 19% (n=19) people with hyperopia, 22% (n=22) people with astigmatism, and 36% (n=36) people with both hyperopia and astigmatism.About 70% of them were women, and 30% were men. The results of our study showed that 15.8% of study participants with normal vision, 26.1% with hyperopia, 22.7% with astigmatism, and 38.9% with both hyperopia and astigmatism had experienced at least 2 falls in the past 12 months. The people with refractive errors showed a higher prevalence of falls; however, the result of the Chi-square test did not reveal any significant differences among these groups (P=0.25). Furthermore, the results of ANOVA for comparing TUG test (test of postural control) results showed no differences among these groups (P=0.64).Conclusion: Vision impairment of older adults due to refractive error is not associated with an increase in falls. Furthermore, TUG test results did not show balance disorders in these groups. Further research, such as assessment of postural control with advanced devices and considering other falling risk factors is also needed to identify the predictors of falls in older adults with eye refractive errors.

Purpose: Refractive errors are the fourth cause of blindness in the world, and if they are not recognized or corrected, they can expose the child to amblyopia and blindness. Epidemiological information is needed to prevent and detect refractive errors. . Due to the limited researches on refractive errors of children in Fars province, this study aimed to determine the prevalence of refractive errors and anisometropia in 6-7 years old children in the city of Fasa. Methods: In this cross-sectional study, we used two-stage cluster stratified random sampling and selected 633 preschoolers. A total of 601 preschoolers were referred to clinic but 596 cases of all were examined. Results of cycloplegic refraction were recorded for statistical analysis. Results: In this study, the prevalence of myopia, hyperopia astigmatism and anisometropia were 6/54%, 10/57%, 32/55%, 3/02%, respectively. Also the rates of the prevalence of astigmatism were 24/16%with the rule, 7/21 % against the rule and 1/17%. oblique Prevalence of refractive errors in boys and girls respectively: myopia 8/01% and 5/17%, hyperopia 10/1% and 11%, astigmatism 31/35% and 33/65%, anisometropia 2/78% and 3/23 %. According to the chi-square test, there was no significant difference between girls and boys in refractive errors and anisometropia. The prevalence of astigmatism according to thewith the rule, against the rule and oblique in boys and girl were as follows: (27/17% and 21/35%), (11/32% and 2/78%), (1/39% and 0/97 %). According to chi-square test, against the rule astigmatism were significantly more prevalent in girls than boys (p<0. 001). Conclusion: According to the result of the present study, astigmatism was the most prevalent refractive error in preschoolers in Fasa province. In comparison to the other studies the prevalence of hyperopia was average amount but myopia was almost high. Anisometropia was not a serious problem. According to the high level of astigmatism and myopia in this study, we recommend other studies should be accomplished in preschoolers in Fars.

A assessment of LASIK for correction of Refractive Errors.Perspective interventional noncomparative case series, 399 eyes (264 patients) with Myopia -Myopia & Astigmatism and! 7 eyes (10 patients) with Hyperopia were involved.all cases were operated with NIDEK EC- 5000 and Chiron Microkeratome. Reguler follow up was one at a day, a WK, a month. 3 months, 6 months and a Year.There were 166 male and 233 female in-group of myopia and myopia with astigmatism (Mean of sphericai Equivalent was-7.8+/-4.2 D), There were seven males and 10 females in-group of Hyperopia (MSE was +5.3+/- 1.3 D).After six months follow up, 99 eayes at mayopia group and 4 eyes at hyperopia group were available. In group of myopia and myopia with astigmatism MSE was -2.7+/-2.3 D and in-group of hyperopia MSE was +3.15+/-3.34 D. After 6 months in myopia group 66.44% wert; within +/-1 D have targeted SE and 88.7% have UCVA better than or equal to 20/40.After 3 months in hyperopia group 166% were within+/-1 D of emmetropia and 100% have UCVA better or equal to 20/40.The mean of regression after 6 months in myapia group was+0.76+/-1.21 and in hyperopia group as -2.3+/-0.64.LASIK is an effective and safe way for reducing the amount of myopia and myopia-astigmatism, but with current algorithm under correction is high. Because of insufficient follow up and low number participant we cannot give a definite conclusion about hyperopia.

Background and Objectives: Carpet weaver women due to long working in inappropriate environment are at risk for certain eye disease. The aim of this study is to determine the refractive errors among carpet weavers women in rural Sephidehkesh of Qazvin.Methods: 28 Carpet weaver women were under optometric eye examinations. Light Intensity at work stations was measured, using luxmeter and eye examinations were done by using the ophthalmoscope and retinoscop. Data were analyzed using one-side T-test.Results: The result of this study showed, general and local light intensity in 13 carpet weaving workshops, respectively 160 and 154 Lux that was much less than the minimum and maximum recommended values of 200 to 300 Lux. Only one of 28 Carpet weaver women was healthy and others were visually impaired. In addition to poor eyesight, workers complained of headache, itching and burning eyes.Conclusion: The results show, due to inappropriate working condition in carpet weaving workshops, most young workers are suffering from eye impairment and is predicted the severity of myopia to increase with working experience and age.