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PubMed1999

Adie syndrome: evidence for refractive error and accomodative asymmetry as the cause of amblyopia.

PURPOSE: To report objective changes in accommodation in a child with Adie syndrome. METHODS: A child aged 2 years 10 months when initially examined was found to have good visual acuity in both eyes, a low degree of hypermetropia (isometropic), and Adie pupil presumed to be caused by chicken pox that had occurred 2 months earlier. Amblyopia developed but responded well to treatment, which involved correction of the refractive error and occlusion therapy. Objective changes in the refraction of the eye were measured on the Canon R1 autorefractor at 3.8 m and 33 cm. RESULT: The degree of accommodation in the affected eye when both eyes were open was markedly reduced. CONCLUSION: The presence of isometropic hypermetropia, which remains uncorrected when Adie syndrome is present, can lead to the development of amblyopia in a child.

Accommodation, Ocular↗
PubMed2004

Visual acuity and refractive errors in a suburban Danish population: Inter99 Eye Study.

PURPOSE: The present study was performed as part of an epidemiological study, the Inter99 Eye Study. The aim of the study was to describe refractive errors and visual acuity (VA) in a suburban Danish population. METHODS: The Inter99 Eye Study comprised 970 subjects aged 30-60 years and included a random control group as well as groups at high risk for ischaemic heart disease and diabetes mellitus. The present study presents VAs and refractive data from the control group (n = 502). All subjects completed a detailed questionnaire and underwent a standardized general physical and ophthalmic examination including determination of best corrected VA and subjective refractioning. RESULTS: Visual acuity </= 0.05 was found in one eye of one subject and VA </= 0.3 in 11 eyes of 11 subjects. The main cause of reduced visual function was strabismic amblyopia. Myopia (</= - 0.5 D, spherical equivalent refraction) was present in 33.1% of right eyes of the total population but in 56.8% of subjects with a university degree. CONCLUSIONS: Strabismic amblyopia was a significant cause of unilateral visual impairment. Myopia was approximately twice as frequent in subjects with a university degree as in the remaining study population.

Adult↗
PubMed1981

Accommodation responses and refractive error.

Previous investigations have reported considerable individual differences in the resting point of accommodation. Recent independent studies in Davis, Calif., and Cardiff, Wales, indicate that part of these variations are related to refractive errors. The average dioptric value of the resting point of accommodation is lowest for corrected myopes, highest for corrected hyperopes, and intermediate for emmetropes. Another part of the variation in resting point is related to individual differences in the far point accommodation. There appears to be no significant relationship between the resting point and near point of accommodation.

Accommodation, Ocular↗
PubMed1996

[Refractive errors and strabismus in premature infants].

AIM: We aimed to investigate the incidence of refractive errors and strabismus in premature infants relative to their individual birth weight. METHODS: We investigated 107 premature infants with birth weight < 1250 g (group A, n = 54) and > 1250 g (group B, n = 53). All children were evaluated at the ages of 6 and 24 months for their spherical equivalent and the presence of high myopia (< or = 6.0 D) and strabismus. RESULTS: At 6 months the spherical equivalent was -0.93 +/- 4.2 D in group A and 1.09 +/- 1.9 D in group B, at 24 months -0.75 +/- 5.0 D vs 1.44 +/- 1.9 D (P < 0.01). At 6 months the incidence of high myopia was 10% in group A and 0% in group B, at 2 years 12% vs 2% (P < 0.01). Low birth weight and a long period of artificial ventilation correlated with the development of high myopia. At 6 months 21% of group A and 8.5% of group B showed strabismus, at 2 years 25% vs. 8.5% (P < 0.01). CONCLUSION: Because of the increased incidence of high myopia and strabismus we recommend routine retinoscopy and orthoptic evaluation at the age of 6 months in every child weighing less than 1250 g at birth.

Birth Weight↗
PubMed2003

Refractive errors, intraocular pressure, and glaucoma in a white population.

OBJECTIVE: To examine the relation of refractive errors to glaucoma and intraocular pressure (IOP) in a defined white population. DESIGN: Population-based cross-sectional and follow-up study. PARTICIPANTS: Persons aged 43 to 86 years living in Beaver Dam, Wisconsin (n = 4926). METHODS: All participants received a standardized assessment of refraction, IOP, and glaucoma at baseline (1988-1990), with IOP remeasured 5 years later (1993-1995). Refraction was defined at baseline as follows: myopia as spherical equivalent of -1.00 diopters (D) or less, emmetropia as -0.75 to +0.75 D, and hyperopia as +1.00 D or more. MAIN OUTCOME MEASURES: Relation of baseline refraction to prevalent glaucoma (defined from IOP, optic disc, and visual field criteria) and incident ocular hypertension (defined as IOP more than 21 mmHg at the 5-year examination in eyes with IOP of 21 mmHg or less at baseline). RESULTS: A myopic refraction was correlated with increasing IOP at baseline (P < 0.001). After controlling for age and gender, persons with myopia were 60% more likely to have prevalent glaucoma than those with emmetropia (odds ratio [OR], 1.6; 95% confidence interval [CI], 1.1, 2.3). In contrast, controlling for age, gender, and baseline IOP, persons with hyperopia were 40% more likely to have incident ocular hypertension than those who were emmetropic at baseline (OR, 1.4; 95% CI, 1.0, 2.0). Myopia was not related to incident ocular hypertension. CONCLUSIONS: In these population-based data, there was a cross-sectional association of myopia with higher IOP and prevalent glaucoma. Similar associations have been found in previous studies. Hyperopia may be associated with 5-year risk of ocular hypertension, a finding that needs further investigation.

Adult↗
PubMed1989

Adaptation ability of subjects with different refractive errors.

In previous studies we have shown that subjects with normal binocular vision adapt to prism-induced heterophorias. In this study we have continued the work by investigating the adaptation ability of subjects with different refractive errors to horizontal prisms. The results showed that emmetropes, late-onset myopes (LOM's), and early-onset myopes (EOM's) can adapt to prism-induced phorias at distance and at near. The early-onset myopes demonstrated the greatest amount of adaptation after 3.5 min of binocular viewing in all cases. However, the differences found between the refractive groups in the amount of adaptation after 3.5 min of binocular viewing are not statistically significant.

Adaptation, Ocular↗
PubMed1996

Effects of continuous light on experimental refractive errors in chicks.

It is possible to induce ametropias in young chicks either by depriving the developing eye of clear form vision with a translucent goggle or by defocusing the retinal image with convex or concave lenses. The refractive properties of the developing chick eye are also altered by raising young birds in a continuous light environment. The effects of superimposing form deprivation or defocus treatments on chicks raised in continuous light are unclear. Newly hatched (n = 31) chicks were raised for 2 weeks under continuous light while wearing either translucent goggles or + 10 or -10 diopter (D) lenses over one eye. Refractive states, corneal curvature and intraocular dimensions were measured periodically by retinoscopy, keratometry and A-scan ultrasound. The birds were sacrificed after 2 weeks and the eyes removed and measured with calipers. Under continuous light, all eyes treated with translucent goggle and -10 D lens developed moderate myopia (-2.6 +/- 0.5 D and -1.4 +/- 0.3 D, respectively) by day 4. The eyes treated with a + 10 D lens developed moderate hyperopia (+ 4.8 +/- 0.5 D) at day 4. Corneal curvatures of all treated eyes were slightly, but significantly, larger than contralateral control eyes by day 4. After 2 weeks of goggle or lens application, all the treated eyes were hyperopic due to corneal flattening. But the eyes treated with a goggle or a -10 D lens still showed relative myopia compared to the fellow eyes (treated minus untreated = -3.8 +/- 0.4 D and -2.8 +/- 0.4 D, respectively), and the eyes treated with a + 10 D lens showed more hyperopia than fellow eyes (treated minus untreated = + 5.1 +/- 0.6 D). Compared with the control eyes, the axial length (mainly vitreous chamber depth) was slightly, but significantly, increased in the eyes treated with a goggle or a -10 D lens, and the axial length decreased slightly in the eyes treated with + 10 D lens. The results suggest that form deprivation and retinal defocus (induced by +/- 10 D lenses) could still induce experimental refractive errors (myopia and hyperopia) in chicks kept under continuous light, but the effects of form deprivation and retinal defocus were partially suppressed by continuous light.

Accommodation, Ocular↗
PubMedDate not supplied

Refractive errors and factors associated with myopia in an adult Japanese population.

PURPOSE: To investigate the refractive status and factors associated with myopia by a population-based survey of Japanese adults. METHODS: A total of 2168 subjects aged 40 to 79 years, randomly selected from a local community, were assessed in a cross-sectional study. The spherical equivalent of the refractive error was calculated and used in a multiple logistic regression analysis to evaluate the relationships between myopia and possible related factors. RESULTS: The mean (+/- SD) of the spherical equivalent was -0.70 +/- 1.40 diopters (D) in men, and -0.50 +/- 1.44 D in women. Based on +/- 0.5 D cutoff points, the prevalence of myopia, emmetropia, and hypermetropia were 45.7%, 40.8%, and 13.5% in men, and 38.3%, 43.1%, and 18.6% in women, respectively. A 10-year increase in age was associated with reduced risk of myopia [men: odds ratio (OR) = 0.53, 95% confidence interval (CI): 0.44-0.62; women: OR = 0.65, 95% CI: 0.54-0.78]. In men, myopia was significantly associated with higher education (high school: OR = 1.6, 95% CI: 1.1-2.3; college: OR = 2.0, 95% CI: 1.3-3.1) and management occupations (OR = 1.6, 95% CI: 1.0-2.4). For women, high income (OR = 1.5, 95% CI: 1.1-2.2), and clerical (OR = 1.5, 95% CI: 1.0-2.4) and sales/service occupations (OR = 1.7, 95% CI: 1.1-2.6) were also associated with myopia. CONCLUSIONS: The prevalence of myopia in a Japanese population was similar to that in other Asian surveys but higher than in black or white populations. Our study confirmed a higher prevalence of myopia among younger vs. older populations, and a significant association with education levels and socioeconomic factors.

Adult↗
PubMed1997

The artifact of retinoscopy revisited: comparison of refractive error measured by retinoscopy and visual evoked potential in the rat.

PURPOSE: The validity of retinoscopy in small eyes has not been clearly established due to uncertainty regarding the source of the ocular reflections assessed during this procedure. A widely cited model which proposes that their origin is the inner limiting membrane of the retina was evaluated in the rat by comparing refractive errors measured by retinoscopy to those measured by visual evoked potentials (VEPs). METHODS: Ten rats were refracted both by cycloplegic streak retinoscopy and by VEP while viewing 0.05 to 0.15 cpd square-wave gratings-reversed at 1.875 Hz. Spherical aberration of the rat eye was assessed as a potentially confounding variable in VEP refraction by sequential retinoscopic refractions across the rat's natural pupil through a 1.5-mm pinhole. RESULTS: All animals were moderately to highly hyperopic by both methods (range = +4.5 to +18.5 D). Spherical aberration was minimal (median = 3.5 D of overcorrected aberration). The median difference between retinoscopic refractions and those by VEP was not significant (+1.94 D more hyperopia by retinoscopy; p = 0.062, Wilcoxon signed rank) but was significantly less than the +9.64 D difference predicted by an inner limiting membrane model (upper 95% limit = +3.76 D). CONCLUSION: This suggests that the origin of the retinoscopic reflex is located in the outer retina rather than at the inner limiting membrane. Correction factors for retinoscopy in small eyes may be smaller than previously assumed.

Animals↗
PubMed1999

Refractive errors in a black adult population: the Barbados Eye Study.

PURPOSE: To describe the prevalence of refractive errors in a black adult population. METHODS: The Barbados Eye Study, a population-based study, included 4709 Barbados-born citizens, or 84% of a random sample, 40 to 84 years of age. Myopia and hyperopia were defined as a spherical equivalent <-0.5 diopters and >+0.5 diopters, respectively, based on automated refraction. Analyses included 4036 black participants without history of cataract surgery. Associations with myopia and hyperopia were evaluated in logistic regression analyses. RESULTS: The prevalence of myopia was 21.9% and was higher in men (25.0%) than in women (19.5%). The prevalence of hyperopia was 46.9% and was higher in women (51.8%) than in men (40.5%). The prevalence of myopia decreased from 17% in persons 40 to 49 years of age to 11% in those 50 to 59 years of age, but increased after 60 years of age. The prevalence of hyperopia increased from 29% at 40 to 49 years of age to 65% at 50 to 59 years of age, and tended to decline thereafter. A higher prevalence of myopia was positively associated (P < 0.05) with lifetime occupations requiring nearwork, nuclear opacities, posterior subcapsular opacities, glaucoma, and ocular hypertension. Factors associated with hyperopia were the same as for myopia, except for occupation, and in the opposite direction. CONCLUSIONS: High prevalences of myopia and hyperopia were found in this large black adult population. The prevalence of myopia (hyperopia) increased (decreased) after 60 years of age, which is inconsistent with data from other studies. The high prevalence of age-related cataract, glaucoma, and other eye conditions in the Barbados Eye Study population may contribute to the findings.

Adult↗
PubMed1991

Exploring the optometric application of expert computer systems: refractive error correction.

Using the commercially available shell programs NeuroShell and EXSYS, example-based and rule-based expert computer systems were developed to explore how such systems could be applied in an optometric environment. To demonstrate such an application, the example-based NeuroShell system was taught to prescribe sphere and cylinder powers for low refractive error myopes. When the system learned with only the chief complaint, habitual prescription and acuity through the habitual, and best refraction with resulting acuity, it predicted the sphere and cylinder powers prescribed by human optometrists within 0.25 diopter 97 and 98 percent of the time, respectively, for 60 test eyes. With a set of only three rules, the rule-based EXSYS system predicted sphere powers within 0.25 diopter of the prescribed powers for 100 percent of the 60 test eyes. Results with these very simple refractive problems suggest that teaching expert computer systems to prescribe ophthalmic lens corrections is possible, and further suggest that the concept could be extended to more complex and challenging patient populations.

Eyeglasses↗
PubMed1986

The effect of refractive error on the accommodative response gradient.

The accommodative responses of early-onset myopes, late-onset myopes, emmetropes and hyperopes were measured over a range of 5 dioptres using an objective infra-red autorefractor. Differences were found between the four refractive groups, with hyperopes accommodating more for near targets than emmetropes, followed by early-onset myopes then late-onset myopes. Moreover a strong correlation between the accommodative response gradient and refractive error was found, suggesting that hyperopes accommodate more to a particular target than do emmetropes or myopes. The results are interpreted in the context of a dual innervation to the ciliary muscle.

Accommodation, Ocular↗
PubMed1986

Need for eye and vision care in an underserved population: refractive errors and other ocular anomalies in the Sioux.

The Native American population has a significant unmet need for eye and vision care. Beginning with the onset of continuous eye care on two reservations in North and South Dakota, a compilation was done of refractive errors and other clinical findings in 1886 Sioux Indians. The results are similar to previous findings in the Navajo, Cheyenne, and Zuni Indians. This paper contributes to the epidemiological characterization of an underserved population, demonstrates the degree of unmet needs before continuous eye care services, and hopefully will aid in the planning, implementation, and evaluation of optometric care for such groups.

Adolescent↗
PubMedDate not supplied

Visual acuity and refractive errors in the elderly in nursing homes.

A total of 268 elderly persons living in eight nursing homes in northern Finland (participation rate 100%) were examined by an ophthalmologist in 1980-1983 in order to describe visual acuity and the occurrence of refractive errors. Uncorrected distant visual acuity in the better eye was less than 0.4 in 76% of the men and 68% of the women, being worse in older subjects than in younger ones. Uncorrected near visual acuity in the better eye was less than 0.1 in 24% of the men and 25% of the women. Hyperopia was found in 78% of the men and 77-78% of the women and myopia in 14-15% of the men and 15-16% of the women. Hyperopia decreased and myopia increased with age. Astigmatism was uncommon and its prevalence figure was not related to sex or age. Only 3% of men and 5% of women were emmetropic. We may conclude that uncorrected distant visual acuity of the population was low, and three out of every four men and two out of every three women were unable to manage their daily activities without difficulties due to the low visual acuity. Also uncorrected near visual acuity was low, and one out of every four persons was practically blind.

Aged↗
PubMed1998

Refractive errors among young adults and university students in Norway.

PURPOSE: This study was initiated to compare the refractive state in a population sample to that among university students in Norway and to that among the general population in other Nordic countries. METHODS: A population sample of 112 individuals and 224 engineering students were randomly selected and examined using automated and clinical refraction in cycloplegia. RESULTS: Statistically significant differences were found in prevalences of myopia (population sample: 33%, students: 47%, p: 0.016) and prevalences of hyperopia (population sample: 47%, students: 30%, p: 0.001) between the two groups. The mean refractive error among the population sample was -0.1+/-2.0 D compared to -0.6+/-2.2 D among the students (p=0.0013). CONCLUSIONS: The population sample had a significantly lower prevalence of myopia and a higher prevalence of hyperopia than the student population. The state of refraction in the population sample was found to be in agreement with results reported from other Nordic countries.

Adult↗
PubMed1981

Photographic screening for strabismus and high refractive errors of children aged 1-4 years.

UNLABELLED: 182 children (age 1-4 years) were photographed by health sisters at the annual screening at the children's health care center as described by Kaakinen (1979). The photographs were examined by an ophthalmologist to diagnose squint and/or refractive error cases based on the typical changes in the corneal and fundus reflexes. The cases found in this way were controlled clinically. RESULTS: 7 pathological cases were detected: 2 esotropias, 1 microesotropia, 2 hyperopias of both eyes, 2 anisocorias. False positive were 6 cases, from which 4 were false positive microstrabismus suspects and 2 cases with asymmetrical fundus reflexes, which were normal. 14 cases failed (9 (4.9%) looked to the side, and 5 (2.7%) were technical failures). For the reliability of the method, a random sample of 20 children, who had normal corneal and fundus reflexes were examined clinically. No anisometropia of over 0.5 diopters appeared among these 20 control cases, and the highest hyperopic and astigmatic errors that appeared were +1.75 diopters. All the astigmatic cases were combined with a slight myopia of -0.5- -1.0 diopters in each case. No higher myopias occurred in this group, and all these 20 children had straight eyes with the cover test at near fixation.

Child, Preschool↗