Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Myopia”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 397 records · Page 22Linked to original sources
PubMed1999

Photorefractive keratectomy for low-to-moderate myopia and astigmatism with a small-beam, tracker-directed excimer laser.

OBJECTIVE: To assess the safety and effectiveness of the Autonomous Technologies Corporation LADARVision excimer laser system for photorefractive keratectomy correction of myopia and astigmatism. DESIGN: A multicenter, prospective, noncomparative case series. PARTICIPANTS: The cohort consisted of 467 eyes corrected for spherical myopia and 211 eyes corrected for myopia with astigmatism. INTERVENTION: Treatments were performed at six sites in the United States using a 6-mm ablation zone for spherical myopes and a 5.5-mm zone with a 1.0-mm blend for astigmats. MAIN OUTCOME MEASURES: Visual acuity, subjective refraction, corneal haze, intraocular pressure, complications, adverse reactions, patient satisfaction, and corneal endothelial changes. RESULTS: Twelve-month follow-up was available on 414 spherical eyes and 175 astigmatic eyes. The results for spherical eyes with correction between -1 and -5.99 diopters (D) were: uncorrected visual acuity (UCVA) of 20/40 or better achieved by 98.1%, 20/20 or better by 72%, 1.8% lost 2 lines and 0.3% lost greater than 2 lines of best spectacle-corrected visual acuity (BSCVA); 76.4% were within 0.50 D of the target correction and 94.4% were within 1.00 D. The results for myopia with astigmatism with spherical equivalent correction between -1 and -5.99 D were: UCVA of 20/40 or better in 97.4%, 20/20 or better in 61.7%, 2.5% lost 2 lines and no eyes lost greater than 2 lines BSCVA; 73.9% were within 0.50 D of the target correction and 95% were within 1.00 D. For spherical myopes combined with myopic astigmats corrected for 6 to 10 D, results were: UCVA of 20/40 or better in 93.4%, 20/20 or better in 61.2%, 2.3% lost 2 lines and no eyes lost greater than 2 lines of BSCVA; 67.2% were within 0.50 D of the desired correction and 87.8% were within 1.00 D. Refractive stability was achieved between 3 and 6 months for the spherical and astigmatic groups. No eyes had corneal haze graded as moderate or greater, and there was no significant decrease in endothelial cell density. CONCLUSIONS: Patients treated for 1 to 10 D of spherical equivalent myopia, with or without astigmatism, showed early refractive stability, excellent UCVA, no significant loss of BSCVA, no loss of endothelial cell density, and very low levels of corneal haze to 12 months after surgery.

Adult↗
PubMed2003

Use of a run-in period to decrease loss to follow-up in the Contact Lens and Myopia Progression (CLAMP) study.

Rigid gas permeable (RGP) contact lenses are initially less comfortable to wear than spectacles. In previous studies evaluating the use of RGP contact lenses to control myopia, more subjects randomly assigned to wear RGP contact lenses have been lost to follow-up than spectacle wearers. Previous rigid contact lens myopia control studies have lost 44% and 47% of the rigid contact lens wearers. This unequal loss to follow-up may compromise the results of the study, so we conducted a run-in period prior to randomized treatment-group assignment to ensure that all participants could adapt to RGP contact lens wear. We enrolled 147 children ages 8-11 years with myopia in the run-in period. Of the 147 subjects, 116 (78.9%) were able to wear RGP contact lenses for at least 40 hours per week and reported that they were "usually comfortable" or "always comfortable." After 3 years, no subjects were lost to follow-up. The run-in period greatly reduced the loss to follow-up suffered by previous RGP contact lens myopia progression studies and may help provide more definitive answers regarding myopia control with RGP contact lenses.

Child↗
PubMed1988

Effect of penetrating keratoplasty using grafts of various sizes on keratoconic myopia and astigmatism.

The records of 72 consecutive keratoconic eyes undergoing penetrating keratoplasty were reviewed for changes in myopia and astigmatism. Ages of the patients averaged 32.7 years. All sutures were removed after three months. Follow-up average was 40.2 months. Results showed an average decrease in myopia of 6.63 diopters (D) in 60 eyes (82.86%) and an average increase in myopia of 1.88 D in 12 of 70 eyes (17.14%). The decrease/increase in myopia and postoperative astigmatism was compared for grafts equal to the opening, grafts smaller than the opening, and grafts larger than the opening. The largest average decrease in myopia was 13.86 D (range 6.63 to 20.00), which occurred when a graft smaller than the opening was used (P less than .01). This group also showed the least postoperative astigmatism (2.82 D) (P less than or equal to .01). From this study, it appears that the use of a graft 0.25 mm smaller than the trephine opening in the host (i.e., 7.50 mm graft/7.75 mm opening) for penetrating keratoplasty in keratoconus is justified. A prospective study is now in progress.

Adolescent↗
PubMed2000

Prevalence of myopia in a sample of Greek students.

PURPOSE: An epidemiological study, concerning the prevalence of myopia among the student population (15-18 years old) of Northern Greece, was carried out. METHODS: Specific questionnaires were used in order to collect data on the refractive condition of students. RESULTS: Myopia prevalence was 36.8% and was found to be more common in females (46.0%) than in males (29.7%). The prevalence increased in students with myopic parents and myopic siblings. It was also found that myopia correlates strongly with nearwork and school performance. CONCLUSION: The study results suggest that myopia is a rather common refractive error in Greek students. Findings also indicate that myopia is probably hereditary and correlates with educational level, intelligence and excessive nearwork.

Adolescent↗
PubMed2001

The development of myopia in Hong Kong children.

PURPOSE: The purpose of this two and one-half year follow-up study is to evaluate the relationship between early academic activities and the development of myopia. METHODS: 128 children randomly selected from 51 pre-schools completed an education and vision assessment study. At the end of the period, the children were 8.5 years old. Data were collected on developmental performance in the areas of cognition, language, social, academic and motor skills. The prevalence of myopia, mean refraction and change of refraction over this period were described in terms of the gender, geographical areas, type of pre-schools and type of primary schools. RESULTS: The prevalence of myopia shifted towards a higher proportion of myopia in all the above categories. The mean refraction at the initial visit was 0.5 D and became about -0.50 D at the follow-up visit. There was no difference in the changes of refraction in relation to the type of pre-school or primary school. The change of refraction was also not related to the educational scores. However, there was a statistically significant difference in the academic scores, in particular the reading scores, between the activity and conventional primary schools. There was also gender difference in language scores between the girls and the boys of the activity schools. There was no difference in all scores between the myopes and non-myopes. CONCLUSION: The present study did not demonstrate a relationship between early academic activities and development of myopia. However, the higher reading scores and the slightly faster progression rate in the conventional schools may indicate an influence of the curriculum on the refractive development. A longer follow-up study may elucidate a clearer trend.

Child↗
PubMed2002

An evolutionary analysis of the aetiology and pathogenesis of juvenile-onset myopia.

The available evidence suggests that both genes and environment play a crucial role in the development of juvenile-onset myopia. When the human visual system is examined from an evolutionary perspective, it becomes apparent that humans, living in the original environmental niche for which our species is genetically adapted (as hunter-gatherers), are either slightly hypermetropic or emmetropic and rarely develop myopia. Myopia occurs when novel environmental conditions associated with modern civilization are introduced into the hunter-gatherer lifestyle. The excessive near work of reading is most frequently cited as the main environmental stressor underlying the development of myopia. In this review we point out how a previously unrecognized diet-related malady (chronic hyperinsulinaemia) may play a key role in the pathogenesis of juvenile-onset myopia because of its interaction with hormonal regulation of vitreal chamber growth.

Animals↗
PubMed2003

The mystery of myopia.

Published data from all parts of the world show that myopia is rare before school age, gradually increases during school life and reaches its highest level of prevalence during the years of most intense study at university. It is widely held that continuous reading harms the eyes, but none of the attempts made so far to reduce accommodative fatigue by introducing pauses during reading and teaching, eye exercises, etc. have been successful in reducing the number of children who develop myopia. However, we should not exclude the possibility that the introduction into schools of better tables, better lighting, more breaks and more sport has not only benefited the general health of children, mentally as well as physically, but has also decreased the development and progression of myopia. More research in this area is needed, but relevant protocols are difficult to establish. The aetiology of myopia is multifactorial and both genes and environment play important roles. Twin studies indicate a strong genetic influence and a weak environmental impact, while extreme myopia prevalences among selected population groups (university students) point to the opposite.

Age Distribution↗
PubMed1988

Myopia: induced, normal and clinical.

A review is given of lid-suture myopia in monkeys, of the natural lower field myopia in the pigeon eye, and of myopias in chick eyes produced by visual occluders. The ametropias produced by ophthalmic lenses, and the pharmacology of experimental myopia, are reviewed. Human studies are reviewed which can be taken as models of the experimental myopias. Two theories of myopic growth are outlined and evaluated.

Animals↗
PubMed2003

The autonomic control of accommodation and implications for human myopia development: a review.

Prolonged nearwork has long been associated with myopia development, however, there is no well described linking mechanism. One theory suggests that if accommodation accuracy during nearwork is not maintained, the defocused retinal image leads to myopia development. Here we review the findings of research aimed at determining whether the autonomic inputs to the ciliary smooth muscle are involved in this type of environmental myopia. We examine whether an autonomic imbalance could be a precursor to axial elongation and the resulting myopia. Accommodation responses, such as tonic accommodation and nearwork-induced accommodative adaptation, as a function of refractive error, are described in relation to an autonomic imbalance model. The collective results of this research point to anomalous accommodation responses, possibly as a result of underlying anomalous autonomic input to the ciliary muscle, being involved in myopia development and progression.

Accommodation, Ocular↗
PubMed1986

[Instrument myopia as a possible source of error in nyktometer examinations].

In comparative studies covering 142 eyes a "night myopia" of 0.5 to 1.5 D was found in 33 eyes with the Nyktometer (Rodenstock) and in 23 eyes with the Mesoptometer I (Oculus). In 17 eyes the same degree of "night myopia" was determined with both instruments, while in 16 eyes it was found to be more severe when measured with the Nyktometer than with the Mesoptometer. In one eye this myopia was only found with the Mesoptometer. This more severe "night myopia" measured with the Nyktometer is probably attributable to "instrument myopia."

Adolescent↗
PubMed1997

Retinal dopamine in the recovery from experimental myopia.

PURPOSE: To address further a possible role for retinal dopamine in postnatal eye growth, we studied the response of retinal dopamine in eyes of chicks recovering from myopia. METHODS: Newborn chicks either received a unilateral translucent goggle to induce form deprivation myopia or were reared with unimpaired visual input. The goggle was removed from half of the chicks on day 7. Myopic, recovering and control never-goggled chicks were studied on days 7, 9 and 14. Eyes were enucleated postmortem and measured in axial and equatorial dimensions with calipers. Retinal levels of dopamine and its principal metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) were assayed by high performance liquid chromatography with electrochemical detection. RESULTS: Compared to contralateral and control eyes, retinas of goggled eyes at each time point had reduced levels of dopamine and DOPAC and a lowered calculated DOPAC/dopamine ratio, an index of dopamine metabolism. In eyes recovering from myopia, all biochemical parameters showed prominent increases by 2 days after goggle removal and had reached the level of both contralateral eyes and control eyes by one week after goggle removal. As evidence of a contralateral effect, the retinas of open eyes of chicks wearing a unilateral goggle demonstrated equal dopamine levels but reduced DOPAC compared to eyes of never-goggled chicks. CONCLUSION: An early rise and eventual normalization of retinal dopamine, DOPAC and the DOPAC/dopamine ratio correlate with recovery from myopia. Combined with recent results from lens rearing experiments, these findings suggest that dopaminergic amacrine cells may participate in visually guided eye growth regulation and not just in the myopia response to visual form deprivation. The retinal biochemical alteration in eyes contralateral to a goggle identifies a previously unappreciated binocular interaction in the chick.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2001

Myopia and contrast sensitivity function.

PURPOSE: to measure the contrast sensitivity function of varying degrees of myopia with two types of optical correction (spectacle lens and contact lens). METHODS: One hundred and five myopic eyes and twenty-eight emmetropic eyes were collected. The myopic group included 105 eyes corrected with spectacle lenses and 71 eyes of them corrected with contact lenses, too; all had corrected vision acuity of 20/20 or better. The myopic eyes were divided into four groups: group 1 (-1D to -3D), low myopia; group 2 (-3.25D to -6D), medium myopia; group 3 (-6.25D to -12D), high myopia; and group 4 (> -12D), severe myopia. Spatial contrast sensitivity was measured using the OPTEC 2000 Contrast Sensitivity System. RESULTS: In groups 1 and 2, no statistically significant difference was found between myopes and emmetropes. In group 3, statistically significant loss of contrast sensitivity at higher spatial frequencies was found for myopic subjects corrected with spectacle lens, but not for myopes corrected with contact lens. In group 4, myopic subjects corrected with spectacle lenses showed significantly reduced contrast sensitivity function at all spatial frequencies; subjects corrected with contact lenses showed statistical sensitivity losses at 6, 12, 18 cycle/degree spatial frequencies. CONCLUSIONS: 1. We may suppose that low and medium myopes (groups 1 and 2), who showed normal contrast sensitivity functions, had no retinal dysfunction. 2. For high myopes, contact lens correction could reduce optical defocus and improve contrast sensitivity function in high spatial frequencies. 3. As retinal function disturbances occurred in severe myopes, the diminished contrast sensitivity was not fully compensated by contact lens correction. 4. Loss of contrast sensitivity might be interpreted as evidence for early retinal function disruption before retinal pathological events occur in severe myopes.

Adult↗
PubMed1998

Evidence that a locus for familial high myopia maps to chromosome 18p.

Myopia, or nearsightedness, is the most common human eye disorder. A genomewide screen was conducted to map the gene(s) associated with high, early-onset, autosomal dominant myopia. Eight families that each included two or more individuals with >=-6.00 diopters (D) myopia, in two or more successive generations, were identified. Myopic individuals had no clinical evidence of connective-tissue abnormalities, and the average age at diagnosis of myopia was 6.8 years. The average spherical component refractive error for the affected individuals was -9.48 D. The families contained 82 individuals; of these, DNA was available for 71 (37 affected). Markers flanking or intragenic to the genes for Stickler syndrome types 1 and 2 (chromosomes 12q13.1-q13.3 and 6p21.3, respectively), Marfan syndrome (chromosome 15q21.1), and juvenile glaucoma (chromosome 1q21-q31) were also analyzed. No evidence of linkage was found for markers for the Stickler syndrome types 1 and 2, the Marfan syndrome, or the juvenile glaucoma loci. After a genomewide search, evidence of significant linkage was found on chromosome 18p. The maximum LOD score was 9.59, with marker D18S481, at a recombination fraction of .0010. Haplotype analysis further refined this myopia locus to a 7.6-cM interval between markers D18S59 and D18S1138 on 18p11.31.

Chromosome Mapping↗
PubMed2004

Genomewide linkage scan for myopia susceptibility loci among Ashkenazi Jewish families shows evidence of linkage on chromosome 22q12.

Mild/moderate (common) myopia is a very common disorder, with both genetic and environmental influences. The environmental factors are related to near work and can be measured. There are no known genetic loci for common myopia. Our goal is to find evidence for a myopia susceptibility gene causing common myopia. Cycloplegic and manifest refraction were performed on 44 large American families of Ashkenazi Jewish descent, each with at least two affected siblings. Individuals with at least -1.00 diopter or lower in each meridian of both eyes were classified as myopic. Microsatellite genotyping with 387 markers was performed by the Center for Inherited Disease Research. Linkage analyses were conducted with parametric and nonparametric methods by use of 12 different penetrance models. The family-based association test was used for an association scan. A maximum multipoint parametric heterogeneity LOD (HLOD) score of 3.54 was observed at marker D22S685, and nonparametric linkage analyses gave consistent results, with a P value of.0002 at this marker. The parametric multipoint HLOD scores exceeded 3.0 for a 4-cM interval, and significant evidence of genetic heterogeneity was observed. This genomewide scan is the first step toward identifying a gene on chromosome 22 with an influence on common myopia. At present, we are following up our linkage results on chromosome 22 with a dense map of >1,500 single-nucleotide-polymorphism markers for fine mapping and association analyses. Identification of a susceptibility locus in this region may eventually lead to a better understanding of gene-environment interactions in the causation of this complex trait.

Alleles↗
PubMed2002

Approaching myopia holistically: a case study and theoretical exploration.

INTRODUCTION: Myopia is a commonly occurring condition that, in Western countries, affects 30%-35% of the population. At present the most common way of treating myopia is by optical intervention by means of spectacles, contact lenses, or surgery. BACKGROUND: An exploration of the history of and scientific rationale for the current methods of treatment are presented. The concept of myopia as a holistic phenomenon and the idea of the possibility of healing are introduced. CASE STUDY: A case study of a patient reducing spectacle strength and using holistic healing techniques to induce changes in myopia is presented together with a statement from the patient. CONCLUSION: It is concluded that the contemporary model of vision that justifies the prescription of negative lenses in cases of myopia needs re-examining in light of the case study presented.

Adult↗
PubMed2003

Comparison of implantable contact lens and laser assisted in situ keratomileusis for moderate to high myopia.

PURPOSE: To compare the results of laser assisted in situ keratomileusis (LASIK) and implantable contact lenses (ICL) in the correction of moderate/high myopia. METHODS: Five hundred fifty-nine LASIK eyes from the Davis Duehr Eye Center, Madison, WI, and 210 ICL eyes from the 14-site U.S. FDA Clinical Trial for ICL for Myopia were compared. These series were concurrently operated on with 8 to 12 D of preoperative myopia and were examined at 1 day, 1 week, 1 month, 6 months, and 1 year postoperatively. The mean baseline myopia was slightly higher in the ICL group, (ICL: -9.8 +/- 1.7 D; LASIK: -9.1 +/- 0.97 D). BSCVA, UCVA, and refractions were collected prospectively in both series. RESULTS: Every index of BSCVA, UCVA, predictability of refraction, and stability of refraction studied favored the ICL over the LASIK procedure. All but one of the indices (UCVA % 20/40 or better) were statistically significant in at least half of the time periods studied. At 6-month follow-up, both the loss of two or more lines (ICL: 0%; LASIK: 2%; p = 0.05) and gain of two or more lines (ICL: 7%; LASIK: 3%; p = 0.04) of BSCVA were better with the ICL. Similarly, efficacy outcomes with the ICL were better with predictability (attempted versus achieved +/-1.0 D) of the ICL at 90%; 76% with LASIK (p < 0.001). In this highly myopic series, UCVA 20/20 or better was 50% with ICL compared with 35% with LASIK (p < 0.001). No serious complications occurred in either series of cases. CONCLUSIONS: The ICL was safer and more effective than LASIK and appears to be a viable alternative to corneal refractive excimer surgery in the treatment of moderate to high myopia.

Adult↗
PubMed1981

Primate myopia.

Studies dealing with the development of myopia in primates are considered as they contribute to our understanding of myopia. Myopia appears to develop in two stages. The first is a lenticular change in eyes which have been focused at nearpoint for long periods; the lens remains continuously accommodated. Since accommodation in monkeys results in an increase in vitreous chamber pressure, a comparable increase in children could induce the second stage--an increase in the size of the vitreous chamber and a corresponding increase in axial length or true myopia. Behavior and personality appear to be related to myopia.

Accommodation, Ocular↗
PubMed1990

Variables related to the rate of childhood myopia progression.

This study was undertaken to examine the relations between the rate of childhood myopia progression and variables available in patient records. Data were obtained from four private optometry practices and two university-based longitudinal studies. Subjects were myopes with a minimum number of refractions between the ages of 6 and 15 years. Spectacle prescription types included single-vision lenses with exact distance correction or slight undercorrection, bifocal lenses, and single-vision lenses with overcorrection. Rates of progression were determined by linear regression. Three analyses were conducted: (1) for all patients, analysis of variance of rate as a function of heterophoria through the habitual nearpoint correction, an index of the amount of myopia at the initial examination age, sex, and clinical location; (2) for patients with esophoria through the distance ametropia correction, analysis of variance of rate as a function of correction type (full correction or slight undercorrection vs. bifocals), amount of myopia at the initial examination age, sex, and location; and (3) for patients with orthophoria or exophoria with ametropia correction, analysis of variance of rate as a function of correction type, amount of myopia at the initial examination age, sex, and location. The index of amount of myopia at the initial examination age was a significant variable, as was location. Patients with nearpoint esophoria through their habitual nearpoint correction had greater rates than patients with nearpoint orthophoria or exophoria with the habitual correction. For patients with nearpoint esophoria through the distance refractive correction, rates were less with bifocals than with full correction or slight undercorrection.

Adolescent↗