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At least 19 recordsLinked to original sources
PubMed1989

Age differences in peripheral refractive error.

Refractive error was measured at 0 degrees to 40 degrees temporal to fixation in 10 young adults (M age = 26 years) and 10 older adults (M age = 63 years). Older adults exhibited a greater amount of sphere (i.e., overall) error, but no more so in the periphery than in the fovea. Although age differences were small, younger adults were found to exhibit more peripheral astigmatism than the older adults. Discrepancies between obtained results and those of Millodot (1985) may be attributed to the relationship between peripheral astigmatism and presenting refractive status. Alternatively, a two-mechanism model of age-related change in lens curvature is capable of accounting for across-study outcome differences. Recommendations are made concerning optimal viewing conditions for the study of age differences in visual perceptual processes.

Adult↗
PubMed1985

Intraocular lens powers used in the triple procedure. Effect on visual acuity and refractive error.

The refractive results of 43 consecutive triple procedures (transplant, cataract extraction, and lens implant) performed by one surgeon were analyzed. Twenty-one out of 43 eyes achieved refractive errors within 2 diopters (D) of emmetropia. The mean refractive error was -1.79 D, and the mean corneal astigmatic error was 2.75 D. Seventy percent of the eyes achieved 20/40 or better corrected acuity. Forty-four percent had 20/80 or better uncorrected acuity. Using the average postoperative keratometry readings from other recent transplant cases and an updated A constant in the SRK regression formula would have placed 39 of 43 eyes (91%) within 2 D of emmetropia with a mean refractive error of -0.07 D. The use of recent keratometry readings in a multiple regression formula is recommended to improve refractive results with the triple procedure.

Cataract Extraction↗
PubMed1990

Effects of intraocular lens position errors on postoperative refractive error.

Previous theoretical attempts to predict the refractive effects of intraocular lens (IOL) misalignment have resulted in conflicting information. Discrepancies in both the potential magnitude and direction of the refractive changes exist in the literature. This paper provides a detailed description of the mathematical framework required to achieve a valid predictive model and a quantitative analysis of the effects of IOL positional errors. The effects of misalignment are shown to influence the spherical refractive component primarily. Astigmatism related to oblique incidence is generally small. Movement of the IOL away from the retina produces myopia, while movement toward the retina produces hyperopia. It is likely that longitudinal IOL positional errors are a principal component of postoperative refractive errors. Alignment errors, on the other hand, must have generally minor effects on refraction.

Astigmatism↗
PubMed1992

Myopia and refractive error in dogs.

The refractive error of 240 phakic dogs of various breeds was measured using streak retinoscopy and averaged (-0.27 +/- 1.41 D relative to infinity). Analysis by breed showed that the German Shepherd, Rottweiler, and Miniature Schnauzer breeds had an increased prevalence of myopia with an average refractive error of -0.86 +/- 1.31 D, -1.77 +/- 1.84 D, and -0.66 +/- 1.05 D, respectively. Myopia also was found in older dogs with marked nuclear sclerosis of the crystalline lens. Fifty-three percent of all German Shepherd dogs in a veterinary clinic population (n = 58 eyes) had a myopic refraction of greater than or equal to -0.50 D; 64% of all Rottweiler dogs (n = 28 eyes) were myopic. An in-depth investigation of German Shepherd dogs, using A-scan ultrasonography, photokeratoscopy, and streak retinoscopy, was done at Guide Dogs for the Blind (San Rafael, CA). By contrast with the results obtained in the veterinary clinic population, the overall average refractive error of guide dog German Shepherd dogs (n = 106 eyes) was +0.19 +/- 0.81 D, and only 15% of these dogs were myopic. The axial length and corneal curvature of myopic eyes did not differ significantly from nonmyopic eyes.

Animals↗
PubMed1987

Refractive errors in children.

Optical correction of refractive errors in infants and young children is indicated when the refractive errors are sufficiently large to cause unilateral or bilateral amblyopia, if they are impairing the child's ability to function normally, or if the child has accommodative strabismus. Screening for refractive errors is important and should be performed as part of the annual physical examination in all verbal children. Screening for significant refractive errors in preverbal children is more difficult; however, the red reflex test of Bruckner is useful for the detection of anisometropic refractive errors. The photorefraction test, which is an adaptation of Bruckner's red reflex test, may prove to be a useful screening device for detecting bilateral as well as unilateral refractive errors. Objective testing as well as subjective testing enables ophthalmologists to prescribe proper optical correction for refractive errors for infants and children of any age.

Adolescent↗
PubMedDate not supplied

Combining refractive error and uncorrected visual acuity to assess the effectiveness of refractive corneal surgery.

Residual refractive error and uncorrected visual acuity are two frequently measures used to assess the effectiveness of refractive corneal surgery. Nordan and colleagues have suggested a Visual Function Index which combines these two measures in one quantitative measure. This article presents a Visual Function Score for radial keratotomy which includes a set of qualitative categories (excellent, good, fair, poor) and specifies the clinical values for refractive error and visual acuity in each category. There was substantial agreement among ophthalmologists who reviewed the category definitions, and we think that the Visual Function Score improves our ability to objectively assess surgical outcome. Application of the score to the Prospective Evaluation of Radial Keratotomy (PERK) Study data yielded closer agreement with refractive error results than with visual acuity values. The Visual Function Score lowered the classification of eyes that were hyperopic but had sufficient accommodation to overcome so that a high visual acuity result could be achieved. The inclusion of astigmatism values would be an important next step in the development of composite measures for the assessment of refractive surgery. In the future, a multifactorial index or score may be used to estimate the outcome of reported surgical procedures.

Adult↗
PubMed1977

The Humphrey Vision Analyzer tm: reliability and validity of refractive-error measures.

Four subjective measures of the refractive error of 42 eyes (21 patients) were obtained by 2 examiners, one using a Humphrey Vision Analyzer TM and the other using a conventional refractor. Each examiner made 2 separate measures of each subject's refractive error, one without and one with an added cylindrical lens chosen at random from a predetermined set of powers and axes. The order of using the instruments and the added lenses was mixed. Measures of the refractive errors differed with the 2 instruments by approximately the same amount on average as did duplicate measures with either instrument. Refractive-error measures obtained with the 2 instruments are about as valid as they are repeatable.

Adult↗
PubMed1991

Genetics of epidermal ridges: a study in subjects with refractive errors.

The dermatoglyphic characteristics of subjects with refractive errors when compared with control group revealed significant differences in both qualitative and quantitative parameters. The loops were increased in male myopics; the whorls were increased in male hypermetropics and astigmatics and the arches were decreased in all types of refractive errors in males. However, the whorls were decreased in female hypermetropics only. The mean total ridge count was significantly higher in male astigmatics only. As regards pattern intensity (fingers) no significant difference in the mean value was observed in either sex with any type of refractive errors when compared with those of controls.

Adolescent↗
PubMed1991

Relation between spherical refractive error and visual acuity.

The relation between a spherical refractive error and visual acuity is investigated and the results compared with previous studies. This study, unlike most of the previous studies, presents a mathematical model that includes a pupil size factor. It also examines a theoretical relation between refractive error and visual acuity which predicts that there should be a linear relation among refractive error (E), the pupil diameter (D), and minimum angle of resolution (A), over a wide range of refractive errors.

Humans↗
PubMed1987

Use of photoretinoscopy as a screening technique in the assessment of anisometropia and significant refractive error in infants/toddlers/children and special populations.

The presence of significant refractive error and/or anisometropia can produce an irreversible decrease in visual function if not detected and treated at an early age. The general consensus is that the earlier a problem is detected, the easier the process of remediation. The authors have examined photoretinoscopy as a means of screening infant/toddlers and/or nonverbal persons for refractive anomalies. Fifty adults and fifty infants/toddlers/children were photographed and the estimated refractive error from review of the pictures was compared to the refractive error obtained from retinoscopy. The results indicate that photoretinoscopy is an effective screening procedure for the detection of significant refractive error and is extremely sensitive to anisometropia.

Adolescent↗
PubMed1989

Changes in refractive error for exotropes treated with overminus lenses.

The refractive changes of pediatric patients who were prescribed overminus lenses for exotropia were evaluated. Overminus lenses means additional minus power over the lenses required to correct the refractive error at distance. Forty exotropic patients, ages 1 to 15 years, were prescribed overminus lenses (-0.50 D to -3.75 D) for a period of 9 to 86 months. A small but significant correlation was found between the initial refractive error and the mean annual change toward myopia. Other factors such as age when treatment was given, duration of therapy, amount of overminus, and the amount of the exodeviation had little effect on the rate of myopic change. The mean annual changes in refractive error for hyperopes (-0.13 +/- 0.44 D, N = 15), emmetropes (-0.26 +/- 0.37 D, N = 17), and myopes (-0.75 +/- 0.77 D, N = 18) were similar to values reported in the literature for nonexotropic children.

Adolescent↗
PubMed1990

A comparison of cycloplegic refraction to the near retinoscopy technique for refractive error determination.

The near retinoscopy technique of refractive error determination was compared to the standard method of cycloplegic refraction using 10 "infants" (3-12 months of age) and 10 "children" (32-109 months of age). There was a significant difference between the techniques for both sphere and cylinder power. Although there was no interaction of refractive technique and age group, the difference between near retinoscopy and cycloplegic refractive error tended to be larger for infants than for children. No significant difference was found when the average refractive values were compared for monocular or binocular conditions and no significant effect was found for either gender or laterality (right versus left eye). Based on these findings, it is suggested that caution be used in substituting the near retinoscopy technique for cycloplegic refraction even utilizing a "correction" factor for the dioptric difference between techniques.

Analysis of Variance↗
PubMed1990

[Refractive errors, strabismus and amblyopia in pre-school screening--experiences using a vision test in kindergarten].

UNLABELLED: Within the framework of mass screenings conducted by the Public Health service section for juveniles, 254 children were examined jointly on a voluntary basis in 5 different kindergartens. The examined children represented in each case 88% of the respective kindergarten groups. The examination programme included, among others, the R5 apparatus (visual acuity in respect of remote objects with and without + 1.5 D), Lang- and DeKa Stereo Test, Cover-and-Uncover Test with remote and near fixation, heterostatic retinoscopy (in 205 children only), ophthalmoscopic fixation test. In addition, the acceptance for U8 and the degree of care in respect of ophthalmological control and treatment were investigated. RESULTS: Strabismus or significant uncorrected errors of refraction were discovered by the on-target tests of covering and uncovering, fixation and retinoscopy in 26 of 205 completely examined children (12.7%). This had not been satisfactorily covered by single tests such as R5-Visus test with the criteria much less than 1.0 (grade 5) or much less than 0.7 (grade 4), respectively stereo tests. The combination of "R5-Test Visus much less than 1.0" and "DeKa Stereo Test not fully identified" attained a sensitivity of 81% with a positive predictive value of only 28%. This combination, therefore, results in too many healthy children being referred to the ophthalmologist. "R5-Test Visus much less than 0.7" and "DeKa Stereo Test not fully identified" attained a sensitivity of 75% with a positive predictive value of 44%. This combination is recommended as long as the R5 or R11 apparatuses are used. The phoria and stereo tests contained in the R5 apparatus are unsuitable for kindergarten screening.(ABSTRACT TRUNCATED AT 250 WORDS)

Amblyopia↗
PubMed1992

Optic nerve crescents and refractive error.

In this paper we discuss whether the presence of an optic nerve crescent might affect the way in which axial length and corneal curvature interact to determine refractive error. Subjective refraction, keratometry, measurement of body height, axial length of the eye, and stereophotography of the optic nerves were performed on 224 subjects, 8- to 25-years-old. Photographs were examined under magnification; optic nerve crescents, if present, were measured in the horizontal dimension. Those measurements were then corrected for magnification due to the eye and the camera. Logistic regression analysis suggested that male gender and myopic refractive error were most directly associated with the presence of a large crescent, whereas axial length, age, and horizontal keratometry reading were less directly associated with the presence of a crescent. The relation between axial length and refractive error differed among those with large crescents compared to those with small or no crescents. Simple regression showed that, for those with a crescent at least 0.2-mm wide, a 1-mm greater axial length was associated with, on the average, 1.26 D of myopia. For those with smaller or no crescents, a 1-mm greater axial length was associated with only 0.66 D of myopia. This difference was statistically significant at the 0.02 level of confidence.

Adolescent↗
PubMed1988

Algebra of sphero-cylinders and refractive errors, and their means, variance, and standard deviation.

Sphero-cylinders and refractive errors can be represented by matrices. Matrix algebra provides methods whereby sphero-cylinders can be added, subtracted, multiplied, inverted, and raised to powers and can have roots extracted. These operations are defined for sphero-cylinders and examples are given. In terms of these operations a number of means of refractive errors are defined: the arithmetic, harmonic, and quadratic means. Furthermore it is possible to define a variance and standard deviation for refractive errors. These quantities should provide a basis for a formal approach to the statistical analysis of populations of refractive errors.

Humans↗
PubMed1987

An evaluation of the NR-1000F Auto Refractometer in high refractive errors.

The manifest refractions of 37 high myopic and 16 high hypermetropic eyes in a total of 28 patients, aged 5 to 42 years, were determined on the Nikon NR-1000F Auto Refractometer. The data obtained were compared with the final clinical prescriptions for these eyes and analysed for degree of agreement for the spherical equivalents, sphere components, and cylinder powers and axes. The Auto Refractometer recordings for all the different refractive components were observed to skew towards more minus in the high myopic eyes but more plus in the high hypermetropes. The possible significance of these skewing patterns is discussed with reference to our earlier studies.

Adolescent↗
PubMed1985

Disease-associated visual image degradation and spherical refractive errors in children.

Retrospective clinical data from 496 eyes of 256 children attending a low vision clinic were analyzed to determine the relation between disease states which involve visual image degradation and refractive error. Refractive data from 1023 normal vision children were used as a control. The low vision children were grouped according to their disease classification and the acknowledged age-of-onset of their visual disability. It was found that there was an overall inability to emmetropize and a trend towards myopia. It was also observed that the diseases which led to myopia were associated with a peripheral or peripheral plus central impairment of vision and that those conditions in which foveal vision was primarily impaired showed a mild hypermetropic trend. Eyes in which the visual impairment was not congenital but occurred before the age of 3 years tended to develop hypermetropia. The deviation from emmetropia decreased with increasing age-of-onset of the visual impairment, as did the variation about the mean refraction. The plastic period for emmetropization is estimated to end at 8 to 9 years of age.

Adolescent↗
PubMed1990

Distribution of refractive errors in patients from Dominica, West Indies.

A total of 779 consecutive private patients requiring spectacles for correction of refractive errors were categorized according to age, sex, occupation and type of refractive error. Virtually all patients (97.1%) were black. The relationship between age, sex, occupation and refractive error was determined and showed that refractive errors were approximately equally distributed between the sexes, but myopia was more common among those with nearpoint occupations. Data also showed that more of the elderly were hyperopic than myopic in contrast to the younger patients who were more often myopic.

Adolescent↗