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PubMed1982

Sex differences in refraction errors up to the age of 15.

A health inquiry concerning vision and corrective lenses at the age of 14 was carried out in a northern Finland series about 12,000 children followed up since birth. Data were obtained from more than 99% of cases. 34% of the girls and 18% of the boys had corrective lenses. 55% of the study population were living in the province of Oulu, and the ophthalmological records of these children were analysed (N 1939). The ophthalmological records covered 67% of the children with lenses in the province of Oulu. 71% of the girls with lenses, and 66% of the boys had these for myopia, both myopia and hyperopia were less common among the boys, but the cases were more pronounced. The children with lenses were on average taller and heavier and the myopic children had a better mean ability at school.

Adolescent↗

PubMed1984

Refractive errors in a Finnish rural population.

Refractive errors in 611 persons living in a rural area were examined. Males numbered 281 and females 330. The age range was from 6 to 85 years. In 73 (11.9%) persons the refraction was myopic (SER less than or equal to 0.5 D) and in 173 (28.3%) hyperopic (SER greater than or equal to + 2 D). Myopia was most frequently detected in persons aged 21-30 years (22.6%), and the proportion of myopia decreased towards both extremes of age. In all age groups females were more myopic than males. In persons aged 21-60 years the most educated proved to have more myopia and less hyperopia than those with less education. In 158 (25.9%) of the eyes, astigmatism was detectable. The degree of astigmatism changed little with advancing age and was independent of sex. In myopic eyes the range of astigmatic error was wider than in hyperopic eyes. The axis of + cylinders was in hyperopic eyes mostly horizontal and in myopic eyes vertical. Anisometropia of 1.25-2.0 D was detected in 24 (4.0%) persons and in 19 (3.1%) persons it was over 2 D.

Adolescent↗

PubMed1990

Retinal detachment following intracapsular cataract extraction.

A retrospective investigation of aphakic retinal detachments following intracapsular cataract extraction during a 12-year period was performed. A total of 8350 eyes had intracapsular cataract extraction in the study period and 118 eyes developed aphakic retinal detachment. The occurrence of retinal detachment is related to age, sex, intraoperative complications, myopia, hyperopia, and pseudophakia. Age and myopia were significantly associated with aphakic retinal detachment. Previous aphakic retinal detachment in the one eye was a strong predictor for the other eye.

Adolescent↗

PubMed2005

Corneal sensation after myopic and hyperopic LASIK: clinical and confocal microscopic study.

AIM: To assess the long term (1 year) effect of myopic and hyperopic LASIK on corneal sensation and innervation. METHODS: 83 eyes of 43 patients having LASIK were evaluated. According to the preoperative spherical equivalent, the eyes were divided into three groups: group 1, myopia from -0.75 to -6.00 D; group 2, myopia from -6.25 to -11.50 D; and group 3, hyperopia from 1.25 to 5.00 D. Corneal sensation was measured and in vivo confocal microscopy (IVCM) was done at the central cornea before, and at 1 month, 3 months, 6 months, and 1 year after LASIK. RESULTS: The mean corneal sensation in group 1 was greater than in groups 2 and 3 at all postoperative measurements. The difference between group 1 on one hand and groups 2 and 3 on the other hand was statistically significant at 1 month and 3 months after LASIK and was not statistically significant afterwards. IVCM study of 27 eyes revealed that the number and length of nerve fibre bundles in the sub-basal region decreased after LASIK and was significantly lower at all times after surgery despite the return of corneal sensation to preoperative level. CONCLUSION: After LASIK, central corneal sensitivity is decreased for as long as 6 months or more. The results suggest that lamellar cutting of the cornea during LASIK impairs corneal sensitivity and is related to the ablation depth. The diameter of ablation too may contribute to this drop in sensitivity. The return of corneal sensations does not directly correlate with the regeneration of nerve fibres as determined by confocal imaging. Sensations return to normal values before complete restoration of normal innervation if this indeed ever occurs.

Adult↗

PubMed2006

Optic disc size in a population based study in northern China: the Beijing Eye Study.

AIM: To determine the optic disc size in the adult Chinese population in an urban and a rural region of Beijing. METHODS: The population based, cross sectional cohort study included 4439 subjects out of 5324 subjects invited to participate (response rate 83.4%). It was divided into a rural part (1973 (44.4%) subjects) and an urban part (2466 (55.6%) subjects). Mean age was 56.2 (SD 10.6) years (range 40-101 years). Colour optic disc photographs were morphometrically examined. Main outcome measure was optic disc area. RESULTS: Optic disc photographs were available for 4027 (90.7%) subjects. Mean optic disc area measured 2.65 (0.57) mm2 (range 1.03 mm2-7.75 mm2). Optic disc area was significantly (p<0.001) correlated with myopic refractive error, with a steep decrease in optic disc area from high myopia to the mid-range of refractive error, a slightly horizontal course in the refractive error range between -8 dioptres and +4 dioptres, and a further decrease in optic disc area towards higher hyperopia. Optic disc area was not related to age (p = 0.14) or sex (p = 0.93) (optic disc area, males: 2.65 (0.56) mm2 versus females: 2.65 (0.57) mm2). "Microdiscs" may be defined as smaller than 1.51 mm2, and "macrodiscs" as larger than 3.79 mm2. CONCLUSIONS: Compared with data of preceding studies, mean optic disc size is larger in Chinese people than in white people. In Chinese people highly hyperopic eyes have significantly smaller optic discs, and highly myopic eyes have significantly larger optic discs than emmetropic eyes.

Adult↗

PubMed2006

Ethnicity-specific prevalences of refractive errors vary in Asian children in neighbouring Malaysia and Singapore.

AIM: To compare the prevalences of refractive errors in Malay, Chinese and Indian children in Malaysia and Singapore. METHODS: Children aged 7-9 years from three schools in the Singapore Cohort study of the Risk factors for Myopia (n = 1962) and similarly aged children from a random cluster sample in the metropolitan Kuala Lumpur area in the Malaysia Refractive Error Study in Children (n = 1752) were compared. Cycloplegic autorefraction was conducted in both countries. RESULTS: The prevalence of myopia (spherical equivalent of at least -0.5 diopters (D) in either eye) was higher in Singapore Malays (22.1%) than in Malays in Malaysia (9.2%; 95% confidence interval (CI) 11.2 to 14.7; p<0.001). Similarly, Singapore Chinese (40.1%) had higher prevalences than Malaysian Chinese (30.9%; 95% CI 1.5 to 16.9). Singapore Indians had a higher prevalence (34.1%) than Malaysian Indians (12.5%; 95% CI 17.4 to 25.9). The multivariate odds ratio of astigmatism (cylinder at least 0.75 D in either eye) in Singapore Malays compared with Malaysian Malays was 3.47 (95% CI 2.79 to 4.32). Ethnicity-specific hyperopia rates did not differ in Singapore and Malaysia. CONCLUSION: The ethnicity-specific prevalences of myopia in Singapore Malays, Chinese and Indians are higher than those in Malaysian Malays, Chinese and Indians. As Malays, Chinese and Indians in Malaysia have genetic make-up similar to that of Malays, Chinese and Indians in Singapore, environmental factors may contribute to the higher myopia rates.

Asian People↗

PubMed1997

Long-term influence of insulin dependent diabetes mellitus on refraction and its components: a population based twin study.

AIM: To study whether refraction of the eye, or some of its components is influenced by duration of insulin dependent diabetes mellitus. METHODS: From the young cohort of the population based Danish Twin Register, containing 20,888 twin pairs born between 1953 and 1982, all twin pairs having one or both partners affected with IDDM were searched. Autorefraction, autokeratometry, and ultrasonic biometric measurements were carried out on 45 twin pairs: 16 monozygotic (MZ) twin pairs, 14 dizygotic twin pairs of same sex (DZss), and 15 dizygotic twin pairs of opposite sex (DZos). To obtain an estimate of the influence of duration of diabetes, the intrapair differences in duration of diabetes were correlated with intrapair differences in refraction and each of its components. RESULTS: Refraction was statistically significantly negatively correlated with duration of diabetes in the DZss group, and axial length correspondingly positively correlated. Surprisingly, refraction and axial length in the MZ group, adjusted for confounding factors, were correlated with diabetes duration in the opposite direction than in the DZss group, although not reaching statistical significance. Lens thickness was statistically significantly positively correlated with duration of diabetes in both MZ and DZ twins. Anterior chamber depth was negatively correlated with duration of diabetes in all the zygosity groups. CONCLUSIONS: Studies of relations between refraction and duration of diabetes show diverging results. In the MZ group, a tendency to reduced axial length and corresponding hyperopia with increasing duration of diabetes was found. However, in the DZ group of same sex the opposite tendency was found. Increasing lens thickness and decreasing anterior chamber depth with increasing duration of diabetes have been confirmed in this study.

Adolescent↗

PubMed1998

Case-control study of the risk factors for age related macular degeneration. France-DMLA Study Group.

AIM: A case-control study was initiated to determine the risk factors for the development of age related macular degeneration (AMD). METHODS: Study participants, who were all white, aged 50-85 years, and were recruited from private ophthalmology practices. Each practitioner enrolled patients with bilateral AMD, who were then matched with controls for sex and age. Environmental factors and systemic and ocular histories were screened. All patients had bilateral red-free fundus photographs and fluorescein angiography. Photographs were classified into pigment epithelium alterations, drusen, geographic atrophy, and exudative AMD. Statistical analysis included the identification of risk factors for AMD. A multivariate analysis was performed at the end of the study. Analysis included the entire study population and was carried out for each stage of AMD. RESULTS: 1844 controls were compared with 1844 patients with AMD. Mean age was 71 years for controls and 72 for cases. Logistic regression identified six major risk factors for AMD (whole population): arterial hypertension (odds ratio (OR) = 1.28), coronary disease (OR = 1.31), hyperopia (OR = 1.33), light coloured irises (OR = 1.22), and lens opacities or previous cataract surgery (OR = 1.55). The significance of vascular risk factors was increased for late stages of AMD, especially the atrophic forms (coronary disease, OR = 3.19). CONCLUSIONS: This large case-control study confirms some of the risk factors previously identified and may contribute to the determination of methods for prevention of AMD.

Age Distribution↗

PubMed2002

Heart defects and ocular anomalies in children with Down's syndrome.

AIMS: To investigate whether ocular anomalies are associated with congenital heart defects in children with Down's syndrome. METHODS: 58 children with Down's syndrome were entered into a retrospective observational study. Children were assigned to heart defect groups based on medical records. Optometric tests had previously been carried out at the homes of the children. RESULTS: A relation between congenital cardiac defects, myopia, and nystagmus was observed. Heart problems were not related to accommodative insufficiency, hyperopia, or strabismus. CONCLUSION: In children with Down's syndrome heart defects were associated with both myopia and nystagmus.

Accommodation, Ocular↗

PubMed2003

Too much or too little: neonatal ocular misalignment frequency can predict later abnormality.

BACKGROUND: 214 orthoptists' infants have been followed for up to 15 years, relating neonatal misalignment (NMs) and first convergence onset to later childhood ocular abnormalities. NMs are shown in a companion paper to reflect the onset of first convergence, but if frequent or absent may predict a higher risk of refractive error and esodeviation. METHODS: In a prospective postal survey, orthoptist mothers observed their own infants during the first months of life and regularly reported ocular behaviour and alignment, visual development, and any subsequent ocular abnormalities. RESULTS: Later strabismus and refractive error were less common in infants who showed NMs occasionally compared with those who never or frequently did. There was a significant linear trend for fewer ocular abnormalities to be found in children with more frequent NMs (p<0.001). Hypermetropes were later to show first convergence than emmetropes or myopes (p = 0.006) CONCLUSIONS: NMs usually reflect an emerging and normally developing vergence system. This study suggests that delayed onset of convergence (and lack of NMs) is associated with later defects, especially hyperopia. Possible causal relations are discussed.

Age Factors↗

PubMedDate not supplied

[Les amétropies statiques du noir camerounais].

PURPOSE: We undertook this study with the aim to determine static ametropias of black Cameroonians as well as their clinical manifestations. It is a prospective study carried out in the Department of Ophthalmology of Douala General Hospital from January 1996 to December 1998. PATIENTS AND METHOD: During this period, all patients who fulfilled our criteria had a skiascopy done under cycloplegia. We thus examined 2,484 patients (4,968 eyes). 66.2% of them were female and 33.8% were male. RESULTS: In our series, hyperopia was found in 51% of the cases, hyperopic astigmatism in 27.5% of the cases, myopic astigmatism in 9.3% of cases, mixed astigmatism in 7.7% of cases and myopia in 4.5% of cases. Distribution of ametropias is influenced by age, not by sex or laterality. DISCUSSION AND CONCLUSION: Functional signs just have an indicative value; only objective refraction under cycloplegia can determine exactly the ametropia.

Adolescent↗

PubMed1981

Variations of vitelliform macular degeneration.

In this study, 33 patients with proven vitelliform macular degeneration were examined. 3 of the 33 (9%) had multiple extrafoveal lesions rather than the typical macular changes. In addition, hyperopia of more than 3 dptr was present in 44% of patients and the condition was noted to produce vision of less than 20/50 in one eye in 40% of cases, indicating that vitelliform patients often are not legally blind.

Adolescent↗

PubMed2003

The effects of constant and diurnal illumination of the pineal gland and the eyes on ocular growth in chicks.

PURPOSE: To investigate the effects of constant or 12-hour cyclic illumination of the pineal gland and the eyes on the growth of the chick eye. METHODS: Chicks (Gallus gallus, Cornell K Strain) were raised either under a 12-hour light-dark cycle of normal light or under constant light, with or without opaque removable hoods that covered the top of the head for 12 hours each day. A second group of chicks was raised under constant light with opaque eye covers that were worn on either both eyes or only the right eye for 12 hours each day. Chicks were placed in the experimental conditions on the third day after hatching and raised for 3 weeks. RESULTS: Pineal gland hoods and eye covers worn 12 hours a day significantly (P < 0.0001) protected the chicks from hyperopia under constant-light conditions. They also reduced the flattening of the cornea caused by constant light. Most striking was the protection afforded the uncovered eye from constant light's effects by the periodic covering of the opposite eye. CONCLUSIONS: A diurnal light-dark rhythm presented to one of three photosensitive organs (the pineal gland and both eyes) can protect the eyes from the effects of constant light. This is most probably due to the maintenance of a melatonin rhythm in the organ receiving the diurnal light rhythm.

Animals↗

PubMed2004

Effects of photorefractive keratectomy-induced defocus on emmetropization of infant rhesus monkeys.

PURPOSE: To investigate whether photorefractive keratectomy (PRK) performed in infant primates can modify emmetropization and therefore could be used to study mechanisms of refractive error development. METHODS: Six healthy rhesus monkeys ranging in age from 2 to 3 months were randomly divided into two groups (n = 3 each). Anisometropia was induced in each animal by performing PRK on one eye. Hyperopic anisometropia was induced in group A monkeys by flattening the cornea of the right eye, whereas myopic anisometropia was produced in group B monkeys by steepening the cornea of the right eye. Corneal morphology and topography, refractive status, and axial growth were evaluated over a 5-month observation period. RESULTS: All the PRK-treated corneas were re-epithelialized and transparent within 3 days after surgery. Subsequently, all the surgically treated eyes exhibited interocular alterations in axial growth rate that were appropriate to compensate for the PRK-induced anisometropia. Specifically, vitreous chamber elongation rates were faster in the eyes with induced hyperopias than in their fellow eyes (0.63 +/- 0.05 mm vs. 0.40 +/- 0.09 mm), but slower in the eyes with induced myopia than in their fellow eyes (0.58 +/- 0.13 mm vs. 0.73 +/-0.10 mm). In some animals, the recovery from the induced anisometropia was facilitated by interocular differences in the rate of corneal flattening. However, the rates of corneal flattening in the treated eyes and their fellow eyes were not significantly different. CONCLUSIONS: PRK-induced defocus predictably alters axial growth rate and the normal course of emmetropization in developing eyes. Thus, PRK is a useful alternative to current methods used to impose experimental refractive errors in laboratory animals. These results also indicate that refractive surgery performed in childhood may affect normal growth of the eye, resulting in decreased predictability of future refractive status.

Animals↗

PubMed2005

Risk factors for accommodative esotropia among hypermetropic children.

PURPOSE: Identification of risk factors for accommodative esotropia may help to determine which children with hyperopia may benefit from early spectacle correction or preventive therapy. METHODS: Participants in the family history study were 95 consecutive patients, aged 18 to 60 months, with accommodative esotropia. Participants in the binocular sensory function study were a subgroup of 41 children enrolled in the family history study within 1 month of onset, while the esodeviation was still intermittent. Participants in the hypermetropia study were 345 consecutive patients, ages 12 months to 8 years, with refractive error of +2.00 D or greater and no esodeviation before age 12 months. RESULTS: In the family history study, 23% of children with accommodative esotropia had an affected first-degree relative, and 91% had at least one affected relative. In the binocular sensory function study, random-dot stereoacuity was abnormal in 41% of children, whereas an abnormal motion VEP, Worth 4-dot, or positive 4-PD base-out prism responses were present in 4% or less of the children. In the hypermetropia study, patients with a mean spherical equivalent of < +3.00 D and significant anisometropia had a 7.8-fold increased risk for accommodative esotropia over nonanisometropic patients. CONCLUSIONS: A positive family history, subnormal random-dot stereopsis, and hypermetropic anisometropia each pose a significant risk for the development of accommodative esotropia. Assessment of these risk factors in conjunction with refractive screening should help to identify those children who are most likely to benefit from early spectacle correction or preventive treatment.

Accommodation, Ocular↗

PubMedDate not supplied

New frontiers for the perioperative data method for IOL calculation following corneal refractive surgeries.

PURPOSE: To evaluate the efficiency of the perioperative data method for intraocular lens (IOL) calculation after correction of myopia and hyperopia with different techniques, including reoperated cases. METHODS: Thirty-five eyes (26 patients) that developed cataract after corneal refractive procedures were evaluated retrospectively. They were categorized according to initial error of refraction into myopes and hyperopes and according to types of refractive procedures into ablative, incisional, both, or others. Reoperated cases were also considered. Number of refractive procedures was noted. Time interval between the first procedure and cataract extraction was indicated. Perioperative method was used to calculate the K value. SRK/T formula was used to calculate IOL power. Difference between intended and finally achieved manifest refraction was an indicator for efficiency of the calculation. RESULTS: Postoperatively, 77.2% of cases had manifest refraction +/-1.5 D of intended refraction. There was no difference between myopes and hyperopes in terms of final manifest refraction, best-corrected visual acuity, and difference between intended and finally achieved manifest refraction. Similarly were groups of different types of surgeries. Efficiency of the method decreased with high axial lengths and low IOL powers. Neither the number of refractive surgeries nor time interval between surgeries affected efficiency of the method. CONCLUSIONS: The perioperative data method is equally effective for myopes and hyperopes. The types, numbers of refractive procedures, as well as the time interval between refractive surgery and cataract extraction do not alter the credibility of the method. In high degrees of myopia, the method gives less accurate results.

Adult↗

PubMed2006

Spectacle correction of heterophoria in hyperopic amblyopic children.

OBJECTIVE: To test the effects of corrective spectacles in hyperopic amblyopic children with heterophoria. METHODS: Visual acuity, refraction and the amount of heterophoria on near (33 cm) fixation were measured before and after 3 weeks of spectacle-wearing in 30 hyperopic amblyopic children with heterophoria. The control group consisted of 20 emmetropic children age-matched to the patients. RESULTS: Uncorrected eyes displayed hyperopic amblyopia accompanied by heterophoria. Corrective spectacles not only attenuated the hyperopia and amblyopia, but also changed the heterophoria to orthophoria. The amount of heterophoria before wearing spectacles was significantly different from that in emmetropic children; but after correction with spectacles, it was the same as that in the emmetropic controls. CONCLUSION: Correction with spectacles is effective for the treatment of heterophoria in hyperopic children with amblyopia.

Accommodation, Ocular↗

PubMed1984

Myopia induction in animals following alteration of the visual input during development: a review.

In this review the effects of changes in the quality of the visual environment on the development of myopia during eye growth in various mammalian and avian species are described. The effect of changes in the light/dark cycle on myopia development has been studied only in the avian eye, mainly that of the domestic fowl. In the eyes of chicks reared from hatching to maturity under continuous illumination, the following findings were reported: myopia, astigmatism, increases in axial length and equatorial width, shallow anterior chamber, increase in corneal diameter, reduction of corneal curvature, increased intra-ocular pressure (IOP), low outflow facility, reduction in aqueous space, buphthalmos, macrophthalmos and glaucoma. The above mentioned changes were consistent in the majority of the studies. In a few experiments where a change in one of the above mentioned parameters was not found, no tendency for the opposite condition was reported. When the illumination level of the visual environment was changed in the avian eye there was an increase in the total size of the eye as well as exophthalmos. Other parameters were not examined. It is quite possible that myopia and eye enlargement in avians are caused by entirely different processes than myopia and eye enlargement in mammals since they can be induced either by changes in the diurnal rhythm or by low intensity light. The involvement of the pineal gland in the control of eye growth in avians is therefore possible. The effect of continuous dark rearing was studied in the avian and in the mammalian eye. In developing chicks reared in continuous darkness some enlargement of the eye took place, but a condition of hyperopia was found as opposed to the expected myopia. This result is in agreement with the results of experiments performed on monkeys and cats reared from infancy to adulthood in complete darkness. The effect of near vision conditions during growth was studied in monkeys, cats and chicks confined to small chambers, cages or rooms. A slight myopia was usually obtained in all of the above species but the incidence of myopia increased consistently in the experimental animals compared to the normal controls. The effect of optically restricting the visual field during growth was studied in chicks. Using special occluders, the eyes of the chicks were exposed only to the frontal fields of vision. This manipulation induced a considerably high myopia and an increase in the axial length of the eye and in the depth of the anterior chamber. Removal of the occluders resulted in a reversal of the induced myopia.(ABSTRACT TRUNCATED AT 400 WORDS)

Accommodation, Ocular↗