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PubMed1999

Refractive errors in children with cerebral palsy, psychomotor retardation, and other non-cerebral palsy neuromotor disabilities.

The aim of this study was to analyse the refractive state of four different groups of children: those with spastic cerebral palsy (CP), aged between 7 and 81 months (N=50); psychomotor retardation, aged between 19 and 70 months (N=16); other neuromotor dysfunctions, aged between 12 and 75 months (N=37); and without psychomotor retardation, aged between 9 and 73 months (N=181). Refractive errors were determined using cycloplegic retinoscopy and non-cycloplegic retinoscopy (Mohindra's technique). We found higher percentages of hyperopia, tendency toward hyperopia, and other refractive anomalies in all the pathological groups of children than in the non-pathological control groups. Children from both the non-CP pathological control group and the group with psychomotor retardation had similar or even higher levels of hyperopia than children from the group with spastic CP. Our results in different age groups indicate a less effective normal emmetropization course in all the pathological groups of children studied. The correction of refractive errors is needed in these children before the end of the neural plasticity period.

Cerebral Palsy↗
PubMed2001

Refractive errors and incident cataracts: the Beaver Dam Eye Study.

PURPOSE: To describe the relation between refractive errors and incident age-related cataracts in a predominantly white US population. METHODS: All persons aged 43 to 84 years of age in Beaver Dam, Wisconsin, were invited for a baseline examination from 1988 through 1990 and a follow-up examination 5 years later from 1993 through 1995. At both examinations, participants had refraction and photographic assessment of cataract, according to a standardized protocol. Myopia was defined as a spherical equivalent of -1.0 diopters (D) or less, hyperopia as +1.0 D or more. The relations between refractive errors at baseline and cataract at baseline (prevalent cataract), 5-year incident cataract, and incident cataract surgery were analyzed by using generalized estimating equations. RESULTS: When age and gender were controlled for, myopia was related to prevalent nuclear cataract (odds ratio [OR], 1.67; 95% confidence interval [CI], 1.23-2.27), but not to cortical and posterior subcapsular cataracts. Myopia was not related to 5-year incident nuclear, cortical, and posterior subcapsular cataracts, but was related to incident cataract surgery (OR 1.89; CI 1.18-3.04). Hyperopia was related to incident nuclear (OR 1.56; CI 1.25-1.95) and possibly cortical (OR 1.25; CI 0.96-1.63) cataracts, but not to posterior subcapsular cataract or cataract surgery. After further adjustment for diabetes, smoking, and education, the association between myopia and incident cataract surgery was attenuated (OR 1.60; CI 0.96-2.64), but the associations between hyperopia and incident nuclear and cortical cataracts were unchanged. CONCLUSIONS: These data support the cross-sectional association between myopia and nuclear cataract seen in other population-based studies, but provide no evidence of a relationship between myopia and 5-year incident cataract. Hyperopia may be related weakly to incident nuclear and cortical cataract.

Adult↗
PubMed2006

Treatment of uncorrected refractive error improves vision-specific quality of life.

OBJECTIVES: To evaluate the benefit of eyeglasses and magnifiers in elderly patients with uncorrected refractive errors. DESIGN: A single-center, randomized, prospective, controlled trial (September 2001 to August 2003). SETTING: Los Angeles County, California. PARTICIPANTS: One hundred thirty-one community-dwelling persons aged 65 and older who had habitual distance visual acuity of 20/32 or worse and whose distant visual acuity, near visual acuity, or both could be improved with eyeglasses, a magnifier, or both by two lines of acuity or more. INTERVENTION: Sixty-six were randomized to receive a prescription and voucher for free eyeglasses, a magnifier, or both immediately, and 65 were randomized to receive a prescription and voucher after the 3-month follow-up visit (the control group). MEASUREMENTS: Primary outcome was vision-specific functioning as measured using the 25-item National Eye Institute-Visual Functioning Questionnaire (NEI-VFQ). Secondary outcomes were distance and near visual acuity and overall functioning as measured using the Rosow-Breslau function questionnaire. RESULTS: In the intention-to-treat analysis of 3-month follow-up data, participants who received the eyeglasses prescription and voucher immediately had greater improvement in NEI-VFQ composite scores than the control group (P<.01). They also had greater improvement in perceptions of their general vision (P<.01), distance visual acuity (P=.03), near visual acuity (P=.04), and mental health (P=.02). CONCLUSION: Correction of uncorrected refractive error, one of the leading causes of visual impairment in older people, improved the vision-specific quality of life of community-dwelling older persons.

Aged↗
PubMedDate not supplied

Postoperative refractive error after simultaneous vitrectomy and cataract surgery.

PURPOSE: To evaluate the effect of vitrectomy on postoperative refraction after simultaneous vitrectomy and cataract surgery. METHODS: We compared the spread between predicted and actual refractions in 206 eyes after a simultaneous vitrectomy, phacoemulsification, aspiration and acrylic lens insertion (combined surgery group), and in 67 eyes after cataract surgery only (cataract surgery group) as control. A vitrectomy was performed for diabetic retinopathy in 127 eyes, macular hole in 32 eyes, rhegmatogenous retinal detachment in 16 eyes, branch retinal vein occlusion in 15 eyes, and other conditions in 26 eyes. In the combined surgery group, 79 eyes had a gas tamponade after insertion of the intraocular lens. RESULTS: The spread between predicted and actual refractions was - 0.05 +/- 1.18 diopters (average +/- SD) in the combined surgery group and +0.55 +/- 1.32 D in the cataract surgery group. The actual refractive errors in the combined surgery group were found to shift toward myopia when compared with the controls. Among the combined surgery group, 127 eyes without a gas tamponade showed a postoperative refractive error of +0.14 +/- 1.11 D, while 79 eyes with a gas tamponade demonstrated an error of -0.36 +/- 1.22 D. CONCLUSIONS: Use of a gas tamponade in the combined surgery group increased the myopic change and was thought to have pressed the intraocular lens forward.

Adult↗
PubMed1990

Local ocular compensation for imposed local refractive error.

Chicks were raised in a low-ceiling environment to find out if their eye growth could compensate for locally imposed hyperopic refractive errors. These chicks became selectively more myopic in the upper visual field than chicks raised in a high-ceiling environment. The vitreous chamber in the low-ceiling birds showed a selective elongation in the ventral region that was not seen in the eyes of the high-ceiling birds. This morphological difference was small, but probably adequate to account for the additional myopia in the low-ceiling birds. These results are consistent with the idea of a visually mediated growth mechanism regulating the local refractive state across the entire visual field so that it matches the customary viewing conditions. Such a mechanism might account for the finding of Fitzke, Hayes, Hodos, Holden and Low (Journal of Physiology, London, 369, 33-44, 1985) that the refractive errors in the lower field are exactly appropriate for focusing the image of the ground on the retina.

Animals↗
PubMed2002

Sensitivity and specificity of visual acuity screening for refractive errors in school children.

PURPOSE: To examine the optimal cutoff point for the use of the visual acuity test to screen for refractive errors in schoolchildren. METHODS: In a sample of schoolchildren between 7 and 9 years old, visual acuity testing was performed using modified ETDRS charts monocularly without optical aids by trained personnel. Cycloplegic autorefraction was performed in each eye. The screening efficacy of using various cutoff points for referring children for further optometric/ ophthalmic assessment was studied. Myopia was defined as a spherical equivalent of at least -0.5 D, hyperopia a spherical equivalent of at least +2.0 D, and astigmatism a cylinder of at least -1.0 D in at least one eye. The sensitivity, specificity, and predictive values were calculated using each patient as a case; a receiver operator curve was plotted. RESULTS: A total of 1,028 children were tested. A satisfactory sensitivity/specificity profile was obtained using a referral criterion of visual acuity worse than or equal to 0.28 logarithm of the minimum angle of resolution in at least one eye. In this scenario, the sensitivity and specificity of this screening test were 72% (95% confidence interval [CI], 68 to 76) and 97% (95%CI, 95 to 98), respectively. The positive and negative predictive values were 96% (95%CI, 93 to 98) and 78% (95%CI, 75 to 82), respectively. CONCLUSIONS: The modified ETDRS visual acuity chart can be used to predict refractive errors in schoolchildren in Singapore in a sensitive and specific manner using a referral criterion of worse than or equal to 0.28 logarithm of the minimum angle of resolution.

Child↗
PubMed2000

A unifying theory of refractive error development.

While retinal defocus is believed to be myopigenic in nature, the underlying mechanism has remained elusive. We recently constructed a theory of refractive error development to investigate its fundamental properties. Our Incremental Retinal-Defocus Theory is based on the principle that the change in retinal-defocus magnitude during an increment of genetically-programmed ocular growth provides the requisite sign for the appropriate alteration in subsequent environmentally-induced ocular growth. This theory was tested under five experimental conditions: lenses, diffusers, occlusion, crystalline lens removal, and prolonged nearwork. Predictions of the theory were consistent with previous animal and human experimental findings. In addition, simulations using a MATLAB/SIMULINK model supported our theory by demonstrating quantitatively the appropriate directional changes in ocular growth rate. Thus, our Incremental Retinal-Defocus Theory provides a simple and logical unifying concept underlying the mechanism for the development of refractive error.

Computer Simulation↗
PubMed1997

Change in postoperative refractive error when vitrectomy is added to intraocular lens implantation.

PURPOSE: To compare the actual and expected refractive errors after intraocular lens (IOL) implantation alone with those after IOL implantation with simultaneous vitrectomy. SETTING: Shinjo Eye Clinic, Miyazaki, Japan. METHOD: One hundred thirty-six eyes had cataract extraction and implantation of a single-piece IOL using a frown incision, continuous annular anterior capsule tear, phacoemulsification, and intracapsular lens fixation. Thirty-six eyes also had vitrectomy. RESULTS: Mean postoperative refractive error was 0.55 diopter (D) +/- 1.34 (SD) in eyes having no vitrectomy and 0.04 +/- 1.24 D in those having vitrectomy. The difference between groups was statistically significant (P = .047; t-test). CONCLUSION: The refraction after simultaneous IOL implantation and vitrectomy shifted toward myopia by a mean of 0.50 D compared with that after IOL implantation alone.

Adult↗
PubMed2003

Comparison of measurements of refractive errors between the hand-held Retinomax and on-table autorefractors in cyclopleged and noncyclopleged children.

PURPOSE: To compare the measurement of refractive errors (sphere, cylinder, and axis) between the hand-held Retinomax and on-table Topcon autorefractors in cyclopleged and noncyclopleged young children. The average bias and measurement agreement were assessed. DESIGN: Observational cross-sectional study. METHODS: The study included 114 cyclopleged and 156 noncyclopleged young children. The mean difference between the two methods and the 95% limits of agreement were calculated to evaluate the average bias. Two types of analyses were conducted to assess the degree of agreement. First, the proportion of the absolute mean differences was presented in different ranges ( 1.0 diopters for sphere and cylinder; 0-10, 11-20 and >20 degrees for axis). Second, the paired t test was conducted to evaluate the consistency of two types of measurements. RESULTS: The data by the Retinomax had mild bias (0.59 diopters) toward a lower sphere data under noncycloplegia but no bias under cycloplegia. For cylinder and axis, there was either no bias or clinically acceptable bias (0.02-0.13 diopters for cylinder and 2-7 degrees for axis) regardless of cycloplegia. Besides the sphere data under noncycloplegia, in general 90% of the mean differences of sphere and cylinder were within 0.5 diopters. More than 97% of the difference in axis under cycloplegia and 68% under noncycloplegia were within 20 degrees. After adjusting for mild bias, the paired t test showed very consistent results. CONCLUSIONS: The data by the Retinomax were consistent with those by the Topcon. The Retinomax is a useful instrument to screen refractive errors in young children.

Child↗
PubMed1979

A clinical analysis of pseudopapilledema. I. Population, laterality, acuity, refractive error, ophthalmoscopic characteristics, and coincident disease.

To clarify clinical features of pseudopapilledema, 142 cases (250 eyes) were analyzed regarding sex, age, race, bilaterality, acuity, refractive error, fundus characteristics, and coincident disease. Ninety-eight cases of identifiable hyaline bodies ([HB] group 1) were compared with 44 cases of pseudopapilledema without HB (group 2). The following results were notable: marked predominance of whites; one third in group 1 were unilateral, and 14% of all pseudopapilledema was unilateral; in only one eye did HB apparently account for diminished acuity; refractive error distribution paralleled that in the general population; anomalous vascular patterns occurred in 20% of group 1 and in 31% of group 2; pigment epithelial changes were found in 33% of group 1 and in 20% of group 2; and a statistically significant association was found with retinitis pigmentosa only. Analysis of field defects is the subject of a companion report.

Adolescent↗
PubMed2004

The influence of age, sex, race, refractive error and optic disc parameters on the sensitivity and specificity of scanning laser polarimetry.

PURPOSE: To evaluate the influence of age, sex, race, refractive error and optic disc topography on the sensitivity and specificity of scanning laser polarimetry (SLP) in the diagnosis of glaucoma. METHODS: A total of 88 normal individuals and 95 glaucoma patients were included in this study. Glaucoma was defined on the basis of both optic nerve damage and visual field defects. Scanning laser polarimetry, optic disc topography, automated perimetry and refractometry were performed in all subjects. The sensitivity and specificity of SLP were assessed applying a previously calculated cut-off to a previously described linear discriminant function (LDF). RESULTS: The sensitivity and specificity of SLP in the study population were 82% and 83%, respectively. Sensitivity and specificity were not affected by age, sex, race, average disc diameter or disc area. The sensitivity of SLP tended to be higher in myopes (93%) than in emmetropes (80%) and hyperopes (71%) (p = 0.08). Sensitivities were higher in individuals with cup areas > 0.96 mm(2) (89%), rim areas < or = 1.36 mm(2) (92%), and cup area/disc area ratios > 0.45 (89%) (p < 0.05). Stepwise logistic regression analysis indicated that the presence of a cup area > 0.96 mm(2) and a rim area < 1.36 mm(2) significantly increased the sensitivity of the LDF, whereas a cup area/disc area ratio < or = 0.45 significantly increased the specificity of the LDF. CONCLUSION: The sensitivity and specificity of SLP may be influenced by refractive error and optic disc parameters that are affected by glaucomatous damage (cup area, rim area and cup area/disc area ratio). These parameters must be considered in studies evaluating the sensitivity and specificity of optic nerve/retinal nerve fibre layer imaging technologies.

Age Factors↗
PubMed1993

[The relationship between the developmental change in visual acuity measurements and change of refractive error in young infants].

219 normal infants aged 3 to 36 months were tested to investigate the relationship between the development of visual acuity and the change of refractive error. 17 infants were tested over a period of time. Visual acuity was assessed by Teller Acuity Cards (TAC), and refractive error was measured by an infrared video refractor (PR1000) without cycloplegics. The results were as follows. 1) The success rate of both tests in 3 to 6 month-old infants was higher than in infants aged 11 to 14 months and 23 to 36 months. 2) Visual acuity showed a rather slow development in infants aged 3 to 12 months. 3) With-the-rule astigmatism of 1 diopter (D) or more occurred with a high incidence in the 3 to 8 month old infants, and decreased with age. 4) The visual acuity in the infants with astigmatism was no different than in those without it. 5) The slow developmental curve of visual acuity measured in 3 to 12-month old infants was probably the result of psychological aversion to the TAC.

Age Factors↗
PubMed2005

The association of astigmatism and spherical refractive error in a high myopia cohort.

PURPOSE: The purposes of this study were to determine whether the degree of myopia influences the presence and degree of total astigmatism, and to assess risk factors of astigmatism in patients with familial nonsyndromic severe myopia. METHODS: We performed a retrospective study of 217 subjects from families with two or more subjects from successive generations with a myopic spherical refractive error of at least -5 D or greater in one eye. Mean myopic spherical equivalent was -10 D and the mean age of myopia onset was 7 years. Refractive error measurements were obtained and the association between the degree of myopia and cylinder power was examined by correlation analysis. RESULTS: The prevalence of astigmatism (1.0 D of cylinder) was 36.1%. With-the-rule astigmatism was most common (55.8%), and the majority of astigmats had between 1.0 and 2.5 D of cylinder (77.6%). Statistically significant associations were found between the presence of astigmatism and risk factors of age and the age of myopia onset. In those patients with astigmatism, however, there was a moderate correlation between the degree of spherical equivalent and cylinder power (r = -0.34, p < 0.0001). Younger age (<16 years) (p = 0.03) was associated with higher cylinder power. CONCLUSIONS: In severely myopic patients, there is a high prevalence of astigmatism that is predominantly with-the-rule. The degree of myopic spherical refractive error is correlated with astigmatism severity but is not a risk factor for the presence of astigmatism.

Adolescent↗
PubMed1982

[Amblyopia and refractive error in patients who suffered from eyelid haemangioma in early childhood].

15 patients with eyelid haemangioma in early childhood had been reevaluated concerning amblyopia and refractive error. There was myopia in 3 of 15 and astigmatism in 9 patients on the tumor side. Amblyopia could be found in all patients with astigmatism higher than 2 diopters, all myopic patients and all patients with localisation of the haemangioma in the lower eyelid. The lower incidence of myopia in our group is discussed In connection with the x-ray therapy which 10 of our patients underwent. It seems necessary in patients with lid haemangioma in early childhood to discover and correct a possible refractive error as soon as possible and in some cases to start orthoptic treatment.

Amblyopia↗
PubMed2004

The relationship between the sagitta of the anterior corneal surface and refractive error of the eye.

Changes in the sagitta of the anterior corneal surface associated with a change in the corneal radius of curvature have been used to calculate the change in refractive error of the eye in two areas: the ablation depth for laser surgery, and the change in corneal thickness associated with orthokeratology lens wear. An approximate formula known as Munnerlyn's formula is commonly used to calculate the refractive error change from sagittal data. This article compares the change in refraction calculated using the approximate formulae with the change calculated from a formula based on an elliptical corneal section. The approximate formula underestimates the ablation depth for a given refractive change and overestimates the refractive change for a given change in corneal thickness, assuming a constant asphericity. When the corneal asphericity increases together with an increase in radius of curvature, a suggested mechanism in orthokeratology, the approximate formula underestimates the change in ocular refraction.

Cornea↗
PubMed2003

Evaluation of refractive error measurements of the Wavescan Wavefront system and the Tracey Wavefront aberrometer.

PURPOSE: To evaluate the accuracy and repeatability of the WaveScan WavePrint system and the Tracey wavefront aberrometer in measuring refractive errors in phakic eyes. SETTING: Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA. METHODS: Using subjective manifest refraction (MR) as the standard, the spherical equivalent (SE), sphere, and cylinder were compared to values measured by WaveScan and Tracey devices in virgin eyes and eyes that had had corneal refractive surgery. Astigmatism was evaluated using vector analysis. The accuracy of the WaveScan and Tracey devices was assessed by 95% limits of agreement (95% LA), and repeatability was analyzed by 2 standard deviations (SDs) and intraclass correlation coefficients (ICCs). RESULTS: The mean differences in SE, sphere, and cylinder between MR and WaveScan were -0.26 diopter (D), -0.12 D, and -0.28 D, respectively, and between MR and Tracey, -0.21 D, -0.01 D, and -0.40 D, respectively. The 95% LA for SE, sphere, and cylinder were -1.09 to 0.57 D, -1.14 to 0.89 D, and -0.95 to 0.40 D, respectively, for WaveScan and -1.37 to 0.95 D, -1.27 to 1.26 D, and -1.16 to 0.35 D, respectively, for Tracey. Vector analysis revealed mean differences of -0.47 +0.07 x 9 degrees between MR and WaveScan and of -0.53 +0.27 x 12 between MR and Tracey. The 2 SDs for SE, sphere, and cylinder were 0.26 D, 0.29 D, and 0.16 D, respectively, for WaveScan and 0.31 D, 0.36 D, and 0.33 D, respectively, for Tracey. The ICCs for SE, sphere, and cylinder were 0.993, 0.992, and 0.902, respectively, for WaveScan and 0.994, 0.992, and 0.764, respectively, for Tracey. The Tracey device measured all eyes evaluated; the WaveScan could not measure 14% of normal eyes and 50% of post laser in situ keratomileusis eyes. CONCLUSIONS: Using MR as the standard, refractive errors measured by the WaveScan and Tracey devices were reliable and reproducible. However, the Tracey device was more robust in its ability to obtain measurements in normal and postoperative eyes.

Adult↗