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PubMed2005

[Prevalence of refractive errors in 7 and 8 year-old children in the province of Western Pomerania].

PURPOSE: To determine the prevalence of refractive errors in 7 and 8 year-old schoolchildren in the province of Western Pomerania. MATERIAL AND METHODS: 140 pupils of elementary schools were examined. Measurements of visual acuity and retinoscopy after cycloplegia were carried out. RESULTS: Prevalence of hyperopia, myopia, and astigmatism was 76.1%, 3.3% and 5.1%, respectively. No statistically significant differences between 7 and 8 year-old children were found. CONCLUSIONS: 1. There is a relatively high prevalence of refractive errors, with hyperopia prevailing, among 7 and 8 year-old schoolchildren. 2. Myopia in young children is a cause for concern an further studies. 3. High prevalence of refractive errors in children calls for systematic examination and focused interviewing by medical professionals of the school health care system.

Child↗
PubMed1986

Comparison of subjective lens preference to objective refractive error measurements in pigtail macaques.

Two measurements can be taken to determine the refractive error in human beings: a subjective, lens preference measurement and objective retinoscopy. This study determined the subjective refractive error in eight pigtailed monkeys by placing lenses of different powers in front of peepholes in a solid wall cage and recording the amount of time each subject used the holes. Retinoscopy measurements were then taken and compared to the subjective findings to determine the degree of similarity between these two refraction methods. The results showed a high correlation between the subjective measurements and the vertical ocular refraction (VOR) and spherical equivalent (SE) (rho = 0.96), further supporting generalizations made from nonhuman primate vision studies to human beings.

Animals↗
PubMed2005

Retinal dysfunction and refractive errors: an electrophysiological study of children.

AIMS: To evaluate the relation between refractive error and electrophysiological retinal abnormalities in children referred for investigation of reduced vision. METHODS: The study group comprised 123 consecutive patients referred over a 14 month period from the paediatric service of Moorfields Eye Hospital for electrophysiological investigation of reduced vision. Subjects were divided into five refractive categories according to their spectacle correction: high myopia (< or = -6D), low myopia (>-6D and < or = -0.75D), emmetropia (>-0.75 and <1.5D), low hyperopia (> or = 1.5 and <6D), and high hyperopia (> or = 6D). Patients with a specific diagnosis at the time of electrophysiological testing were excluded. Only the first member of any one family was included if more than one sibling had been tested. All tests were performed to incorporate ISCEV standards, using gold foil corneal electrodes where possible. In younger patients skin electrodes and an abbreviated protocol were employed. RESULTS: The mean age of patients was 7.1 years with an overall incidence of abnormal electrophysiological findings of 29.3%. The incidence of abnormality was higher in high ametropes (13/25, 52%) compared to the other groups (23/98, 23.5%). This difference was statistically significant (chi2 test, p = 0.005). There was also a significant association between high astigmatism (>1.5D) and ERG abnormalities (18/35 with high astigmatism v 20/88 without, chi2 test, p = 0.002). There was no significant variation in frequency of abnormalities between low myopes, emmetropes, and low hyperopes. The rate of abnormalities was very similar in both high myopes (8/15) and high hyperopes (5/10). CONCLUSIONS: High ametropia and astigmatism in children being investigated for poor vision are associated with a higher rate of retinal electrophysiological abnormalities. An increased rate of refractive errors in the presence of retinal pathology is consistent with the hypothesis that the retina is involved in the process of emmetropisation. Electrophysiological testing should be considered in cases of high ametropia in childhood to rule out associated retinal pathology.

Adolescent↗
PubMed1986

Screening of infants for strabismus and refractive errors with two-flash photorefraction with and without cycloplegia.

35 1/2-year-old and 31 1-year-old children were screened by two-flash photorefraction for strabismus and refractive errors with and without cycloplegia. The sensitivity of the method to detect refractive errors was tested with an optical demonstration eye. All the children were examined clinically to compare the sensitivity of the method. Every child co-operated with the photography, but 4 children did not co-operate in the clinical examination and were thus excluded from the refractive material, as were also two cases of esotropias which were found. There were no false positive or negative strabismus cases. The total refractive material consisted of 120 eyes. The method was clearly more sensitive for refractive errors with cycloplegia. Even one hyperopia of +5.25 D(OD) and +6.0 D(OS) was underestimated without cycloplegia. In the material there were no cases of anisometropia of over 1.0 D in spherical equivivalent that would cause a potential risk for amblyopia. A rather good correlation of refractive results existed with the method in cycloplegia. With partial overlapping of emmetropic and moderate hyperopic cases. The screening of children aged 1/2-1 year with two-flash photorefraction is simple to perform. The underestimation of symmetrical hyperopias should be accepted when cycloplegia is not used. Only one successful photograph of each child is necessary for the interpretation.

Accommodation, Ocular↗
PubMed2006

The prevalence of refractive errors among schoolchildren in Dezful, Iran.

AIM: To determine the prevalence of refractive errors among schoolchildren in urban and rural areas of Dezful County, Iran. METHODS: In a cross-sectional study, using random cluster sampling, 5721 Dezful schoolchildren were selected from 39 clusters. The participants in the study totalled 5544; 3673 elementary and middle school students and 1871 high school students. For the former group, cycloplegic refraction and for the latter, non-cycloplegic refraction was tested. In all participants, uncorrected visual acuity and best corrected visual acuity were determined, and those with a visual acuity of 20/40 or worse, underwent a complete ophthalmic examination to determine the cause of visual impairment. A spherical equivalent of -0.5 diopter (D) or worse was defined as myopia, +2.0 D or more was defined as hyperopia, and a cylinder refraction greater than 0.75 D was considered astigmatism. RESULTS: The uncorrected visual acuity was 20/40 or worse in the better eye of 224 schoolchildren (3.8% of participants). This figure (percentage) was 14 (0.03%) based on their best corrected visual acuity and 96 (1.7%) with their presenting vision. According to results of cycloplegic refraction, 3.4% (95% confidence interval (CI), 2.5 to 4.4) of the primary and middle school students were myopic and 16.6% (95% CI, 13.6 to 19.7) were hyperopic. For high school students, these rates were 2.1% (95% CI, 0.7 to 3.5) and 33.0% (95% CI, 24.9 to 41.1), respectively, with non-cycloplegic refraction. In the multivariate logistic regression for primary and middle school students, myopia was correlated with age (p = 0.030), and hyperopia was correlated with age (p<0.001) and area of residence (p = 0.007). In high school students, hyperopia again showed a correlation with their area of residence (p = 0.029). CONCLUSION: The present study reveals the considerable prevalence rates of refractive errors among schoolchildren in Dezful County and the high rate of an unmet need for their correction. Although myopia is not very prevalent, the high rate of hyperopia in the studied population emphasises its need for attention.

Adolescent↗
PubMed1993

Refractive errors in Hong Kong Chinese pre-school children.

Five hundred and seventy Chinese children aged between 36 and 65 months were recruited for refractive examination. The results show that both the spherical and cylindrical components of the refractive error tend to decrease with increasing age, although the changes were not statistically significant. The results of the present study, together with those of earlier studies carried out on Hong Kong Chinese children of different ages, show a pattern in the change of refractive errors in local children during the first 17 years of life. The combined results show that the average spherical refractive error decreases rapidly in hyperopic power during the 1st and the 6th to the 10th years of life; the astigmatic power decreases rapidly in the 1st year of life and remains thereafter rather constant until the age of 17 years.

Aging↗
PubMed1987

Refractive error changes in law students.

We report two separate studies: a retrospective survey and a longitudinal study; both were designed to assess the changes in refractive error of a group of young adult law students. The retrospective survey compared the previous spectacle correction to the current refractive error in the ocular examination records of 87 members of the class of 1982 law students who were examined at the University of California, Berkeley School of Optometry. Forty-one students (47.1% of the sample, 12.9% of the entire class of 318) increased at least -0.50D in myopia in at least one eye. In the longitudinal study, we followed 16 first year law students for 6 months, measuring refractive error. Five eyes (15.6%) became at least +0.50D more hyperopic, and 12 eyes (37.5%) became at least -0.50D more myopic. These data represent analysis of a small number of eyes over a short period of time. An adult myopic shift is nonetheless evident. A methodology for accumulation of more meaningful data on the specific ocular component changes responsible for this effect is discussed.

Adult↗
PubMed2000

Long term follow up of premature infants: detection of strabismus, amblyopia, and refractive errors.

AIM: To establish recommendations for long term ophthalmological follow up of prematurely born infants. METHODS: 130 infants with a gestational age (GA) <37 weeks and born between 1 November 1989 and 31 October 1990 were enrolled in a prospective study about the development of strabismus, amblyopia, and refractive errors. Infants were subdivided in three groups according to GA: A <28 weeks (n=32), B >/=28-</=32 weeks (n=64), C >32-<37 weeks (n=34). Ophthalmological assessment took place at the postconceptional age of 32 weeks, at term and at 3, 6, 12, and 30 months post term. At the age of 5 years parents received a questionnaire and a majority of the children was examined again (n=99). RESULTS: At the age of 5 years 46 infants were known to have strabismus (n=29) and/or amblyopia (n=22) and/or refractive errors (n=22). Statistical analysis showed that gestational age, duration of supplementary oxygen, and duration of hospitalisation were important predictive variables for the development of strabismus, amblyopia, or refractive errors (SAR) at the age of 5 years (p<0.05). Infants with a GA </=32 weeks had a significantly higher risk of developing SAR than infants with a GA >32 weeks, who developed an incidence comparable with the normal population. Strabismus developed mainly in the first year of life and at the age of 5 years. Most infants with amblyopia were detected at the age of 2-3 years. Refractive errors were found in the first year of life and at the age of 2.5 and 5 years. CONCLUSION: Infants with a GA <32 weeks should be selected for long term ophthalmological follow up. These infants should be screened at the age of 1 year, in the third year of life (preferably at 30 months), and just before school age (including testing of visual acuity with optotypes).

Amblyopia↗
PubMedDate not supplied

Refractive errors among students of a postprimary institution in a rural community in south-eastern Nigeria.

OBJECTIVE: To determine the prevalence and types of refractive errors seen among students of Girls' Secondary School, Akegbe Ugwu in Nkanu West Local Government area of Enugu State, Nigeria. METHODS: A questionnaire documented the students' personal data, their chief complaints and past ocular history. This was followed by unaided visual acuity assessment then assessment with pinhole, anterior segment examination, fundoscopy, non-cycloplegic objective and subjective refraction in those found to have an unaided visual acuity of less than 6/9 in either eye and improved vision with pinhole. RESULTS: A total of 355 students aged 12 -21 years was tested. Out of these, 9 (2.53%) had uncorrected vision worse than 6/9 in either or both eyes. Uncorrected refractive error accounted for the reduced vision in 7 cases 5 of which were myopia. CONCLUSION: There is a prevalence of refractive error of 1.97 % among students of this rural girls' secondary school in South-Eastern Nigeria. The low prevalence of myopia (1.4%) found agrees with the report that, though the most common refractive cause of visual impairment globally, it is relatively rarer in Africans.

Adolescent↗
PubMed2002

Refractive surgery for refractive errors which cause strabismus. A report of 8 cases.

PURPOSE: While excimer laser refractive surgery is a well known procedure for correcting refractive errors, its use in adult patients with accommodative or partially accommodative esotropia who wish to remove their glasses, and those with high anisometropia and exotropia has not been extensively studied. We report our experience treating these two conditions with refractive surgery. METHODS: A retrospective review of the records of 8 adult patients with stable refractive error who underwent refractive surgery by the LASIK procedure. Three patients had accommodative esotropia, 3 had partially accommodative esotropia, and two patients had myopic anisometropia and exotropia. RESULTS: The LASIK refractive treatment corrected the strabismic deviation related to the hyperopia in the accommodative and partially accommodative esotropic patients. It also corrected the exotropia in the myopic anisometropic patients with exotropia. CONCLUSIONS: Refractive surgery is effective in treating accommodative and partially accommodative esotropia in adults and in cases of myopic anisometropia with exotropia.

Accommodation, Ocular↗
PubMed2002

[Congenital ptosis: amblyogenic refractive errors, amblyopia, manifest strabismus and stereopsis related to the types of ptosis. Data on 77 patients and review of the literature].

BACKGROUND: Former reports on amblyogenic refractive errors, amblyopia and binocular vision in congenital ptosis usually comprise all forms of ptosis without any differentiation. This study is an analysis of different kinds of ptosis. PATIENTS AND METHODS: 154 eyes (98 ptotic eyes) of 77 patients with congenital ptosis aged > or = 1 year (56 unilateral ptoses: 45 simple, 1 with rectus superior paresis, 7 with Marcus Gunn's syndrome, 2 congenital oculomotor palsies, 1 unilateral fibrosis syndrome; 21 bilateral ptoses: 10 simple, 2 with bilateral double elevator paresis, 7 blepharophimosis syndromes and 2 bilateral fibrosis syndromes) were investigated concerning visual acuity, refractive error (94 % in cycloplegy), strabismus and stereo acuity. As amblyogenic refractive errors were defined: astigmatism > or = ldpt, anisometropia > or = 1 dpt (spherical equivalent) and hyperopia > or = 3 dpt; amblyopia was defined as visual acuity less than 1.0 or a difference between both eyes of at least 0.2. RESULTS: Altogether were found: Hyperopia > or = 3 dpt in 28.6 % (n = 28); astigmatism > or = 1 dpt in 63.3 % (n = 62), anisometropia in 27.3 % (n = 21), amblyopia in 65.3 % (n = 64), strabismus in 29.9 % (n = 23) and stereopsis in 76.6 % (n = 59). In unilateral simple ptosis, astigmatism of the fellow eye was found in 26.8 % (n = 14). In unilateral ptosis, esotropia was 21.4 % (n = 12), in bilateral ptosis, exotropia 19 % (n = 4), as well as astigmatism > or = 3 dpt 26.2 % (n = 11). As was to be expected, ptosis groups with motility disorders were associated with higher rates of strabismus and amblyopia. The blepharophimosis syndrome could be differentiated by the typical lid anomalies. CONCLUSION: The subgroups of congenital ptosis differ in frequency of amblyogenic factors. In unilateral ptosis these are also frequent in the fellow eye.

Adolescent↗
PubMed2004

Photorefractive keratectomy for pediatric anisometropia: safety and impact on refractive error, visual acuity, and stereopsis.

PURPOSE: To establish the safety and possible efficacy of excimer laser photorefractive keratectomy (PRK) for treatment of pediatric anisometropia. DESIGN: Interventional case series METHODS: This is a prospective, noncomparative interventional case series at an individual university practice of photorefractive keratectomy in 11 children aged 2 and 11 years with anisometropic amblyopia who were unable or unwilling to use contact lens, glasses, and occlusion therapy to treat the amblyopia. The eye with the higher refractive error was treated with PRK using a standard adult nomogram. The refractive treatment goal was to decrease the anisometropia to 3 diopters or less. Main outcome measures were cycloplegic refraction, refractive correction, degree of corneal haze, uncorrected and best spectacle-corrected visual acuity, and stereopsis over 12 months. RESULTS: All patients tolerated the procedure well. The mean refractive target reduction was -10.10 +/- 1.39 diopters for myopia and +4.75 +/- 0.50 diopters for hyperopia. The mean achieved refractive error reduction at 12 months for myopia was -10.56 +/- 3.00 diopters and for hyperopia was +4.08 +/- 0.8 diopters. Corneal haze at 12 months was minimal. Uncorrected visual acuity improved by 2 or more lines in 6 (75%) of the eight children able to perform psychophysical acuity tests. Best spectacle-corrected visual acuity improved by 2 lines in 3 (38%) of patients. Stereopsis improved in 3 (33%) of nine patients. CONCLUSIONS: Pediatric PRK can be safely performed for anisometropia. The refractive error response in children appears to be similar to that of adults with comparable refractive errors. Visual acuity and stereopsis improved despite several children being outside the standard age of visual plasticity. Photorefractive keratectomy may play a role in the management of anisometropia in selected pediatric patients.

Amblyopia↗
PubMed1983

Photorefraction: A useful tool to detect refraction errors.

A simple photorefraction method using simultaneous photography of corneal and fundus reflexes have been used to screen 239 children aged 10 to 15 months for significant refraction errors. The photorefraction results were calibrated to those of cycloplegic retinoscopy. A good agreement was found between the 2 sets of values. The frequency distribution of refraction errors were similar to those presented by Ingram (1979). The aim to detect hyperopia greater than or equal to +2 or myopia greater than or equal to -4 diopters together with significant anisometropia or astigmatism was fulfilled with high reliability. Low degrees of hyperopia, myopia and astigmatism might be missed. Photorefraction therefore is considered to be a reliable, simple and cheap tool with high sensitivity and specificity in screening small children for significant refraction errors.

Astigmatism↗
PubMed1999

Photoscreening for refractive errors in children and young adults with severe learning disabilities using the MTI photoscreener.

PURPOSE: To test the potential ability of the MTI photoscreener to facilitate screening for significant refractive errors in children and young adults with severe learning disabilities. METHODS: Thirty-eight patients with severe learning disabilities from a special school were examined with the photoscreener, and underwent cycloplegic refraction, an ophthalmological and an orthoptic examination. The age at examination, the cause of learning disability, the pupil size, the number of photographs required for accurate interpretation, the co-operation of the subject and the presence or absence of strabismus were recorded. An educational psychologist had performed a psychological assessment on all the children. The results of the cycloplegic retinoscopy were compared with the photorefraction results. RESULTS: A photorefraction was possible in 37 patients and cycloplegic refraction in all the patients. The patients had severe learning difficulties with an intelligence quotient of less than 50. All the patients had behavioural problems, 9 patients had associated cerebral palsy, 8 had chronic epilepsy, 1 patient was brain damaged from a non-accidental injury and 1 from a road traffic accident. The mean age of the patients was 10.0 +/- 4.9 years (range 3-18 years), the average pupil diameter during photoscreening was 6.1 +/- 0.9 mm (range 4-8 mm) and the average number of photographs required for each subject was 2.1 +/- 0.9 (range 1-4). The photoscreener detected 10 patients with a manifest strabismus. There was one false positive and one false negative result giving a sensitivity of 92.8% and a specificity of 90%. CONCLUSION: The examination of children with severe learning disabilities for refractive errors can be extremely difficult. The MTI photoscreener is an effective means of screening such children and young adults for refractive errors and strabismus so that the children with these abnormalities may be targeted for a more detailed evaluation.

Adolescent↗
PubMed2004

[Prevalence of refractive errors in Norway].

BACKGROUND: The aim of this study was to determine the prevalence of refractive errors among young and middle-aged adults in Norway. MATERIAL AND METHODS: Refractive errors were measured with an autorefractor in a population-based sample of young (20-25 years) and middle-aged (40-45 years) adults participating in a health study (HUNT) conducted in Nord-Trøndelag county in Norway in 1996-97. RESULTS: A total of 3137 persons (1248 young and 1889 middle-aged adults) with corrected visual acuity >0.5 (in either eye) were included. About half of the population (51.8% among the young and 52.3% among the middle-aged adults) were emmetropic. The prevalence of myopia was 35.0% in the young adult group and 30.3% in the middle-aged group. Myopia was significantly higher in women aged 20-25 years (36.4%) than in men aged 40-45 years (28.1%). Prevalence of hyperopia increased with age from 13.2% (20-25 years) to 17.4% (40-45 years). INTERPRETATION: The results show a relative high prevalence of myopia in the general population of Norway.

Adult↗
PubMed2003

Development of the National Eye Institute refractive error correction quality of life questionnaire: focus groups.

OBJECTIVE: To identify the content area for a questionnaire designed to measure the vision-targeted, health-related quality of life for persons with well-corrected refractive error. DESIGN: Cross-sectional study. PARTICIPANTS: Fifty-two focus groups were conducted with 414 patients from 5 geographically diverse ophthalmic and optometric sites to identify the content area of a questionnaire for use among persons with myopia and hyperopia. METHODS: A standard protocol was used to structure each focus group discussion, and groups were led by centrally trained moderators at each participating site. Results were summarized and analyzed using a standard set of codes. Qualitative and quantitative analyses were conducted. MAIN OUTCOME MEASURE: Self-reported observations or comments about vision, vision correction, and other aspects of quality of life. RESULTS: Among the 414 participants, 9262 mentions of comments were recorded. The most frequent comments reported by participants were about types of vision correction, followed by comments with their own vision and vision-related symptoms. The distribution of comments by topic domain was generally similar across types of correction and type of refractive error. The most frequent specific comments about glasses concerned problems with reading, adjustment between near and far vision, and appearance. The most frequent comments about contact lenses included those on symptoms such as dry eyes, itching and tired eyes, and headaches, and negative comments about ease of use. The most frequent comments among patients with surgical correction concerned fewer driving problems; fewer symptoms; and improvement in vision, recreation, and comfort. Participants provided equal numbers of positive and negative comments about glasses. Twice as many positive as negative comments were given by contact lens wearers, and 4 times as many positive comments were provided by patients who had undergone surgical correction. CONCLUSIONS: Using focus groups, we were able to identify content areas and aspects of visual functioning in persons with refractive error that are not measured by standard visual acuity testing in the clinic or by other vision-targeted, health-related quality of life instruments such as the 25- or 51-item National Eye Institute-Visual Functioning Questionnaire. The similarity of problems mentioned across refractive error type and correction method suggests it will be possible to develop a single questionnaire with adequate content validity to compare the impact of different modes of correction in vision-targeted, health-related quality of life.

Adult↗
PubMed1994

Induced refractive errors and pattern electroretinograms and pattern visual evoked potentials: implications for clinical assessments.

Refractive errors were induced in normal subjects by means of positive dioptre lenses to reduce visual acuity (VA) from an initial level of 20/20 to 20/100 and then to 20/200. Pattern electroretinograms (PERGs) and pattern visual evoked potentials (PVEPs) were simultaneously recorded at each of these 3 levels of VA using high contrast checkerboard stimuli subtending 11' and 42' of visual arc. Attention was paid to PERG and PVEP variables used for clinical assessments. The findings confirmed the need to take refractive errors into account because, in some cases, latencies and particularly PERG amplitudes fell outside normal limits with decreased VA, especially when using smaller checks.

Adult↗