Type Of Refractive Error Research Articles

Making Sense of Refractive Surgery in 2001: Why, When, for Whom, and by Whom?

Making Sense of Refractive Surgery in 2001: Why, When, for Whom, and by Whom?

State of the autonomous (autonomic) nervous system in general diseases accompanied by myopia

Myopia is a type of refractive error of the eye characterized by the fact that the rays from the image of objects gather in focus before reaching the retina, in front of it. Divergent rays fall on the retina and create light scattering circles. To reduce these, people with myopia squint their eyes.

The Influence of Refractive Correction Upon Disorders of Vergence and Accommodation

Clinical care routinely includes prescription of lenses that compensate for the distance refractive error. Indeed, refractive correction is so commonly prescribed that we often neglect its potential effects on disorders of binocular vision. We report improvement of binocular function that resulted 1 or more months after prescription of an initial spectacle correction for 143 nonstrabismic patients who had a refractive error and either a vergence anomaly (28%), an accommodative anomaly (8%), or both (64%). Refractive correction was estimated objectively with an autorefractor and subjectively refined without cycloplegia. Most corrections were low to moderate in power, essentially following Orinda Study guidelines. Recovery of normal vergence and accommodative function varied according to refractive error type (79% of hyperopic astigmats recovered; 20% of myopes recovered), direction of astigmatic axes (67% recovered who had against-the-rule; 45% with with-the-rule recovered), age (63% below age 12 years recovered; 41% older than age 13 years recovered), and vergence anomaly (67% of patients with fusional vergence dysfunction recovered; 38% of those with basic exophoria recovered). These results suggest that improvement in acuity is not the only reason for prescription of a refractive correction--prescription of even small corrections should be considered as these can dramatically improve vergence and accommodative function for many patients.

Visual problems in Hong Kong primary school children

School children in Hong Kong who fail an Education Department vision screening at the age of five or six are referred to eyecare agencies for a full eye examination. Three hundred and ninety-one consecutive cases seen at the Hong Kong Polytechnic were analysed to obtain a breakdown of the type of refractive errors causing reduced vision among children starting primary school. There was a tendency towards myopia and with-the-rule astigmatism. Exotropia was more commonly encountered than was esotropia. Strabismus and amblyopia were predominantly associated with anisometropia and astigmatism. Key words: vision screening, retractive error, primary school children, Chinese, strabismus. Hong Kong

THE DISTRIBUTION OF REFRACTIVE ERRORS IN NIGERIA

A clinical study of the refractive errors of 349 females aged between 5 and 69 years and 473 males aged between 3 and 62 years was undertaken. This report describes the prevalence of the different types of refractive errors with regard to sex and age.

Refractive error change at the United States Air Force Academy--class of 1985.

A retrospective study was conducted at the United States Air-Force Academy (USAFA) to determine the incidence and change in refractive error over a 2.5-year period between the entrance and third academic year physical examinations. For all 994 eyes (497 cadets aged 17 to 21 years) at entrance, there were 37.3% hyperopes, 18.5% emmetropes, and 44.2% myopes of -0.25 D or more, by spherical equivalent (SPEQ). A significant (p less than 0.001) mean SPEQ change of -0.18 D, -0.21 D, and -0.57 D occurred for the hyperopic, emmetropic, and myopic eyes, respectively, over this period. A myopic change of -0.25 D or more was seen in 47.7%, 41.3%, and 74.0% of the hyperopic, emmetropic, and myopic eyes, respectively, with a clinically significant myopic shift of -0.50 D or greater seen in 21.3%, 25.0%, and 55.1% of these refractive error types, respectively. Myopia progression was derived separately from those eyes showing any amount of myopic shift (greater than or equal to -0.12 D), and was -0.42 D, -0.52 D, and -0.75 D for the hyperopic, emmetropic, and myopic eyes, respectively. There was a higher incidence and rate of myopia increase in the higher refractive errors, whether hyperopic or myopic. These findings suggest that 17- to 21-year-olds are not as safe from a myopic change as thought previously, particularly during an intensive educational program.

Ocular anomalies: a comparison of learning disabled and nonlearning disabled elementary school children.

This study compared descriptive data, obtained via retinal reflex photography, concerning ocular anomalies of 439 learning disabled elementary school children, 1657 kindergarten and Grade 1 nonlearning disabled children, and 724 nonlearning disabled children in Grades 2 to 6. Ocular factors included refractive and nonametropic errors as well as severity of the problem. The learning disabled sample had a significantly higher incidence of refractive error than the normal samples in Kindergarten and Grade 1 but lower incidence than the normal sample in Grades 2 to 6. The learning disabled group had a significantly higher incidence of myopia in one or both eyes than did the kindergarten and first grade normal group. No such difference for myopia existed between the learning disabled and the normal sample in Grades 2 to 6. Incidence of hyperopia in both eyes was significantly lower in the learning disabled than in the kindergarten-first grade sample; however, hyperopia in one eye only was greater for the learning disabled than for the older normals. Significant differences between the younger and older normals existed for all types of refractive error except hyperopia in only one eye. Severity of the problem differed significantly between the learning disabled and the kindergarten-first grade sample in the classes of severe and minimal, not at all when comparing learning disabled and older normals, and in all classes when comparing younger and older normals. The learning disabled also had a significantly higher incidence of nonametropic anomalies than did the normal group. Implications relating refractive error and near environment were discussed.

High Hyperopia in Leber's Congenital Amaurosis

Few studies comment on the type of refractive errors found in patients with Leber's congenital amaurosis. The association of an uncomplicated infantile form of this condition with high hyperopia but without systemic complications has been suggested. In a retrospective study, we identified 11 patients who satisfied the criteria for the diagnosis of this subtype of Leber's congenital amaurosis. All of our cases were found to have at least +6.00 diopters of hyperopia on cycloplegic refraction. No systemic abnormalities were found in any of these children. We suggest that high hyperopia be included in the diagnostic criteria of this specific form of Leber's congenital amaurosis.

Studies in refraction. I. The precision of retinoscopy.

A clinical study was done to determine how precisely ophthalmologists perform retinoscopy. Ten subjects were examined by five ophthalmologists on two separate occasions. Statistical analysis of the results showed that the physicians' precision was unaffected by patients' sex or type of refractive error; the physicians in general agreed in their estimates of the magnitudes of the refractive errors, but their precision varied significantly; cylinder power was measured more precisely than sphere power; and right eyes were measured more precisely than left eyes. Quantitative estimates are given for the variability of replicate retinoscopic measurements. Suggestions are made for techniques of clinical retinoscopy which may minimize certain errors.

The distribution of refractive errors among children attending Lumbini Eye Institute, Nepal

Uncorrected refractive error is an important cause of childhood blindness and visual impairment. To describe the patterns of refractive errors among children attending the outpatient clinic at the Department of Pediatric Ophthalmology, Lumbini Eye Institute, Bhairahawa, Nepal. Records of 133 children with refractive errors aged 5 - 15 years from both the urban and rural areas of Nepal and the adjacent territory of India attending the hospital between September and November 2010 were examined for patterns of refractive errors. The SPSS statistical software was used to perform data analysis. The commonest type of refractive error among the children was astigmatism (47 %) followed by myopia (34 %) and hyperopia (15 %). The refractive error was more prevalent among children of both the genders of age group 11-15 years as compared to their younger counterparts (RR = 1.22, 95 % CI = 0.66 - 2.25). The refractive error was more common (70 %) in the rural than the urban children (26 %). The rural females had a higher (38 %) prevalence of myopia than urban females (18 %). Among the children with refractive errors, only 57 % were using spectacles at the initial presentation. Astigmatism is the commonest type of refractive error among the children of age 5 - 15 years followed by hypermetropia and myopia. Refractive error remains uncorrected in a significant number of children.

Ocular morbidity among primary school children of Dhulikhel, Nepal

Knowledge of disease pattern in children can help design preventive and curative strategies. To study the pattern of ocular morbidity among the primary school children. All the children of randomly-selected five government primary schools of Dhulikhel were included in this study. A complete eye examination was done in all children including color vision, loupe examination, refraction and Schiotz tonometry. Funduscopy and automated perimetry were done in selected children. A total of 466 primary school children were included in the study, of which 466 children 47 (10.08 %) had ocular morbidity. Refractive error was the commonest type of ocular morbidity in 11 (2.36 %). Hypermetropia was the commonest type of refractive error (0.84 %) in contrast to myopia (0.64 %). Conjunctivitis was the second common type of ocular morbidity (1.71 %). Glaucoma suspects accounted for 1.28 %, xexophthalmia 1.07 %, blephatitis 0.85 %, amblyopia 0.43 %, color blindness 0.43 %, conjunctival nevus 0.43 %, glaucoma 0.43 %, and strabismus 0.43 %, while congenital abnormalities were less common. Refractive error is the commonest form of ocular morbidity in primary school children.

Pattern of refractive errors among the Nepalese population: a retrospective study

Refractive errors are a major cause of visual impairment in the population. To find the pattern of refractive errors among patients evaluated in a tertiary care hospital in the western region of Nepal. The present hospital-based retrospective study was conducted in the Department of Ophthalmology of the Manipal Teaching Hospital, situated in Pokhara, Nepal. Patients who had refractive error of at least 0.5 D (dioptre) were included for the study. During the study period, 15,410 patients attended the outpatient department and 10.8% of the patients were identified as having refractive error. The age of the patients in the present study ranged between 5 - 90 years. Myopia was the commonest refractive error followed by hypermetropia. There was no difference in the frequency of the type of refractive errors when they were defined using right the eye, the left eye or both the eyes. Males predominated among myopics and females predominated among hypermetropics. The majority of spherical errors was less than or equal to 2 D. Astigmatic power above 1D was rarely seen with hypermetropic astigmatism and was seen in around 13 % with myopic astigmatism. "Astigmatism against the rule" was more common than "astigmatism with the rule", irrespective of age. Refractive errors progressively shift along myopia up to the third decade and change to hypermetropia till the seventh decade. Hyperopic shift in the refractive error in young adults should be well noted while planning any refractive surgery in younger patients with myopia.

Refractive Errors, Intelligence and Social Mobility

Existing evidence concerning the relationship between refractive error and intelligence, and the determinants of the former, is reviewed. This leads to the expectation that myopia and hypermetropia entail some tendency towards upward and downward social mobility respectively. Two hypotheses were framed accordingly, and tested with samples of ametropic school‐children and normal controls. The associations between type of refractive error, test performance and parental occupation were in conformity with the predicted patterns and highly significant. A tentative model is suggested which takes account of the time dimension in the mobility process, and the potential implications of the findings emerging from this exploratory investigation are discussed.

The Effect of Correction of Refractive Errors on the Distant and Near Vision of School Children

Recent interest in the eye problems of school children has resulted in directing the attention of educators, not only to deficient visual acuity among pupils but to other eye difficulties commonly regarded as handicaps to learn ing. Some of these do not prevent a child from passing the usual visual acuity test given at a distance of twenty feet, yet cause eye-strain and impaired performance in seeing at book or desk distances. This has resulted in attract ing particular attention to the behavior of pupils' eyes at the reading distance. The present study consists of a comparison of the results of visual acuity tests made at the usual distance of twenty feet and also at the reading dis tance. It takes into account the refractive errors of school children and the effect of glasses on their vision as measured at the two distances. A group of one hundred cases was formed from children of school age for whom glasses had been prescribed following diagnosis of refractive errors. The age range was from 6 to 18 years and the median age was 10. Each case received a complete eye examination to establish its eligibility for the group but this study is limited to a consideration of the results of the following tests only: a. Results of tests of refraction. These were the conventional ophthal mological tests made in the course of eye examination. In conformity with previous practice and the procedure of a number of other investigators the cases were grouped according to the type of refractive error, with cases of hypermetropia and hyperm?tropie astigmatism in one classification and those of myopia and myopic astigmatism in another. Eighty per cent of the cases fell in the hyperm?tropie group and 20 per cent in the myopic group. Of these the median amount of hypermetropia, estimated to the nearest test lens power was 1.25 diopters and the median amount of myopia was 1.62 diopters. b. Results of a test of visual acuity at twenty feet. The familiar Snellen Test was used and will be referred to hereafter as the Distance Test.