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At least 19 recordsLinked to original sources
PubMed2004

Impact of family history of high myopia on level and onset of myopia.

PURPOSE: To investigate the impact of a positive family history of high myopia on the level and onset of myopia and its ocular components. METHODS: A cross-sectional study was conducted. The participants (aged 17 to 45 years) were categorized into four groups: normal, mild, moderate, and high myopia. The age of first glasses for myopia was used as the onset of myopia. The impact of the family history on the level and the onset of myopia was quantified. Parental effect on corneal curvature (CC), anterior chamber depth (ACD), and axial length (AXL) was analyzed. RESULTS: The study included 185 normal subjects, 170 mild, 140 moderate, and 392 high myopes. Family history was strongly associated with the probands' status (P < 6 x 10(-12)). When there was >or=1 highly myopic parent, the odds ratios (ORs) of developing mild or moderate myopia were between 2.5 and 3.7 (95% CI: 1.1-6.5) and the ORs of having high myopia were > 5.5 (95% CI: 3.2-12.6). A strong association (P = 2 x 10(-6)) between parental myopic state and the AXL in the subjects was also found, but there was no statistical relationship for ACD or CC. There was an association between high myopia in parents and the onset of myopia in children. Siblings had a weaker association with the level of myopia and had no effect on the onset of myopia. CONCLUSIONS: This study found strong familial effects on the level and onset of myopia even after adjusting for environmental factors. The parental effect on ocular components in their offspring was primarily on AXL.

Adolescent↗
PubMed1995

How applicable are animal myopia models to human juvenile onset myopia?

Investigations into the plasticity of eye growth and refractive error development have significantly expanded our knowledge of animal models of myopia in the last 15 yr. The applicability of this information is as yet undetermined, but hopefully this information will be useful in learning more about human myopia. This paper presents a critical review of the animal myopia literature as those data relate to the human condition. Differences between the chicken, tree shrew, and primate animal models of myopia are outlined, and the various experimental paradigms used to investigate refractive error development and ocular growth in the chicken are compared. Specific arguments against the application of animal models of myopia to the etiology of human juvenile onset myopia include the following: (1) there is no deprivation of form vision in the environment of the school-aged child as severe as that required to induce myopia in animals; (2) the sensitive period for deprivation myopia in animals appears to be too early to account for human juvenile onset myopia; and (3) studies in the chicken using spectacle lenses to create dioptric blur involve a choroidal thickness modulation that has no human analog. Ultimately, the results of investigations into the cellular and biochemical modulation of eye growth in animals may be the most relevant to human myopia.

Animals↗
PubMed2005

[Comparison of retinal morphology and ultrastructure in defocus-induced myopia and form-deprivation myopia in rhesus monkeys].

OBJECTIVE: To investigate the changes of retinal ultrastructure of defocus-induced myopia and form-deprivation myopia in infant rhesus monkeys. METHODS: A -3.00 D spectacle lens (n = 9) or diffuser lens (n = 6) was worn over one eye and a zero-powered lens over the fellow eye in 15 healthy rhesus monkeys ranging in age from 1 to 1.5 months. The eyes were examined periodically with corneal topography, cycloplegic retinoscopy, A-scan ultrasonography, and optical coherence tomography (OCT). Three months later, light and electron microscope were used to observe the changes of the retina. RESULTS: In 15 monkeys, all eyes treated with -3.00 D spectacle lens or diffuser lens developed defocus-induced myopia or form-deprivation myopia. Not only defocus-induced myopia, but also form-deprivation myopia showed elongation of rod outer segment, decreased membrane disc of cone outer segment, increased clearance of the membrane disc and decreased thickness of the neurosensory retina (RNL) as compared with the control eyes (P < 0.05). There were no significant differences between the mean OCT and histomorphometric thickness of RNL and retinal pigment epithelium (RPE) after the correction of dehydration (P > 0.05). CONCLUSIONS: There are significant differences in retinal ultrastructure between experimental myopic eyes and control eyes. But the morphological changes in the retina of the defocus-induced myopia showed no significant difference as compared with form-deprivation myopia. The role of changes of retinal ultrastructure in the development of myopia needs further studies. OCT can be used to examine the changes of RNL and RPE in experimental myopia in vivo.

Animals↗
PubMed2002

Genetic loci for pathological myopia are not associated with juvenile myopia.

The purpose of this study was to evaluate chromosomal regions previously linked to pathological myopia for linkage to juvenile myopia in a sample of myopic children and their families. Of 125 families with a myopic child participating in the Orinda longitudinal study of myopia, 53 submitted 221 buccal swab samples for genetic analysis. Myopia in proband children was defined as -0.75 D or more myopia in both meridians on cycloplegic autorefraction (1% tropicamide). Affected status in parents and siblings was obtained by survey. DNA was extracted from buccal mucosal cells, amplified by polymerase chain reaction (PCR), and then analyzed with seven markers for chromosome 12 and five markers for chromosome 18 in the regions previously associated with pathological myopia. LOD scores were not significant for any marker tested. The largest positive LOD score was 0.15 for GATA30F04. Model-free methods using a SimIBD approach suggested a possible linkage at one marker, GATA6H09 (P = 0.003), but these results were not supported by transmission disequilibrium test (TDT) analysis. The statistical power to detect LOD scores of > or =1.0, assuming homogeneity, was estimated at 93.2%. We found no confirmatory evidence of linkage between juvenile myopia and regions of chromosomes 12 and 18 previously associated with pathological myopia.

Child↗
PubMed2004

Candidate high myopia loci on chromosomes 18p and 12q do not play a major role in susceptibility to common myopia.

BACKGROUND: To determine whether previously reported loci predisposing to nonsyndromic high myopia show linkage to common myopia in pedigrees from two ethnic groups: Ashkenazi Jewish and Amish. We hypothesized that these high myopia loci might exhibit allelic heterogeneity and be responsible for moderate /mild or common myopia. METHODS: Cycloplegic and manifest refraction were performed on 38 Jewish and 40 Amish families. Individuals with at least -1.00 D in each meridian of both eyes were classified as myopic. Genomic DNA was genotyped with 12 markers on chromosomes 12q21-23 and 18p11.3. Parametric and nonparametric linkage analyses were conducted to determine whether susceptibility alleles at these loci are important in families with less severe, clinical forms of myopia. RESULTS: There was no strong evidence of linkage of common myopia to these candidate regions: all two-point and multipoint heterogeneity LOD scores were < 1.0 and non-parametric linkage p-values were > 0.01. However, one Amish family showed slight evidence of linkage (LOD>1.0) on 12q; another 3 Amish families each gave LOD >1.0 on 18p; and 3 Jewish families each gave LOD >1.0 on 12q. CONCLUSIONS: Significant evidence of linkage (LOD> 3) of myopia was not found on chromosome 18p or 12q loci in these families. These results suggest that these loci do not play a major role in the causation of common myopia in our families studied.

Adolescent↗
PubMed1996

Clinical findings before the onset of myopia in youth: 4. Parental history of myopia.

BACKGROUND: We conducted a study to compare variables in children who were initially emmetropic and became myopic to those in children who remained emmetropic. This paper examines parental history of myopia in the two groups of children. METHODS: A cohort of initially emmetropic children was given eye and vision examinations at 6-month intervals for 3 years. Data on parental history of myopia were obtained by questionnaire. RESULTS: A greater proportion of children in the became-myopic group had myopic parents compared to children in the remained-emmetropic group. The sensitivity for onset of myopia was 0.95 and specificity was 0.38 if at least one parent was myopic. A sensitivity of 0.36 and a specificity of 0.87 were found for both parents being myopic. There was a significant association between parental history of myopia and development of myopia in the children in the study (p < 0.01 by chi 2 for categorization of whether neither, one, or both parents were myopic for children in the became-myopic and remained-emmetropic groups). CONCLUSION: Parental history of myopia is a risk factor for the development of myopia.

Child↗
PubMed1998

Baseline characteristics in the Myopia Progression Study, a clinical trial of bifocals to slow myopia progression.

BACKGROUND: Retrospective studies have indicated that myopic children with nearpoint esophoria experienced slower myopia progression if they wore bifocal glasses rather than single-vision glasses. A small, 18-month clinical trial also supported that finding, but the results were not statistically significant. The Myopia Progression Study was funded by the National Eye Institute to test more rigorously the efficacy of bifocals, compared with single-vision glasses, in slowing myopia progression in children with nearpoint esophoria. A secondary objective of the study was to identify other variables that might influence the rate of myopia progression. This report describes the design and methods of the Myopia Progression Study and the baseline characteristics of the subjects. METHODS: A 3-year, randomized clinical trial was initiated. Subjects were children between 6 and 12 years of age who were myopic (at least -0.50 D in each eye) and who demonstrated nearpoint esophoria by the von Graefe technique. RESULTS: Eighty-two children were enrolled. After blocking by gender and clinical site (two sites), subjects were randomly assigned to one of the two treatments: correction with single-vision spectacle lenses or correction with bifocal lenses having a +1.50 D add in a flattop segment. The average degree of myopia at baseline was -2.31 D (SD = 1.31 D). CONCLUSION: This clinical trial can be expected to determine the effectiveness of bifocal glasses in slowing the progression of myopia in children with nearpoint esophoria.

Child↗
PubMed2004

Susceptibility to form-deprivation myopia in chicks is not altered by an early experience of axial myopia.

PURPOSE: Studies in humans and primates suggest that early visual experience may influence eye growth and refractive development later in life. In this study, we asked whether experimentally-induced myopia in 1-week-old chicks influences the responsiveness to form deprivation at a later age (4 weeks old). METHODS: A group of White Leghorn chicks ("twice deprived," N = 12) were monocularly deprived of form vision with white translucent diffusers at 3 days of age for 4 days. The diffusers were then removed, and the chicks were allowed 3 weeks of normal vision to age 27 days before being deprived again for 4 days. Another group of chicks ("once deprived," N = 9) were monocularly deprived of form vision at age 27 days for 4 days. Refractive errors, corneal curvatures, and axial ocular dimensions were measured by retinoscopy, infrared videokeratometry, and A-scan ultrasonography, respectively. Measurements were performed daily during the periods of deprivation and at approximately 3-day intervals in between treatments and after the final treatment period. RESULTS: The magnitude of the form-deprivation myopia induced by 4 days of deprivation at 27 days of age was significantly smaller than that induced by the same treatment at 3 days of age (-4.1 vs. -9.8 D; paired t-test, p < 0.01). This difference in induced myopia reflects optical scaling with increasing eye size because the deprivation-induced changes in vitreous chamber depth were not significantly different for the two deprivation periods (0.37 vs. 0.35 mm, paired t-test, p = 0.65). The induction of myopia at the younger age did not affect the susceptibility to form-deprivation myopia at the older age; there was no difference in the response to form deprivation at the older age between the once-deprived and twice-deprived groups (-3.5 vs. -4.1 D; unpaired t-test, p = 0.50). There was also a significant correlation between the amount of axial elongation induced in individual eyes during the first and second periods of deprivation (r = 0.631, p < 0.05). CONCLUSIONS: The induction of form-deprivation myopia at a young age does not affect the response to form deprivation at a later age. The significant correlation between the axial elongation induced in individual eyes over the two successive periods of deprivation suggests individual differences, possibly genetic in origin, in the susceptibility to form-deprivation myopia in chicks.

Animals↗
PubMed1993

Biomechanical considerations in high myopia: Part III--Therapy for high myopia.

Clinical procedures for the treatment of high myopia are updated in this third part of a report on high myopia. After a discussion of testing techniques and refractive approaches for high myopia, an examination of therapeutic drug experiences shows their relative merits. The author believes that more investigation of beta blocker and epinephrine topical solutions is needed pertaining to the treatment of high myopia. Theoretically, such agents could improve deficient arterial perfusion of the highly myopic eye, and could be helpful in retarding scleral creep. Lifestyle recommendations include patient advice on accommodative reduction and proper exercise techniques. Low impact aerobics may have merit for highly myopic patients since the improved cardiovascular efficiency they can provide may improve the deficient arterial perfusion of their retinas. A summary of the three-part report on high myopia concludes the article. The physiological patterns of high myopia dovetail into the biomechanical considerations showing that a scleral pathogenesis hypothesis of myopic development is a viable working theory. The author's clinical procedures reflect the influence of that theory. If research were redirected from deprivation studies to investigating biomechanical considerations and pharmacological approaches to high myopia, the author contends that dramatically improved treatment regimens could result.

Biomechanical Phenomena↗
PubMed2005

Family history of myopia is not related to the final amount of refractive error in low and moderate myopia.

BACKGROUND: Previous research has found an association between family history and presence of myopia. It is possible that family history also could be related to the final amount of refractive error developed. If that were true, then family history of myopia could have predictive value for the amount of refractive error a child or young adult would develop after first lens prescription. METHODS: Consecutive myopic adult outpatients were enrolled during the year 2003. They received a refractive examination and a questionnaire concerning age of onset of lens use, academic achievement, and parental history of myopia. RESULTS: In the group of 271 mild and moderate myopes (myopia lower than -6 D) there were 157 subjects with at least one myopic parent and 114 subjects without family history. The presence or absence of a family history of myopia was not associated with either the final myopic refractive error (-3.2 +/- 1.5 D and -2.9 +/- 1.3 D, respectively, P = 0.08) or the age of onset of lens use (17.0 +/- 6.2 years vs 18.1 +/- 6.7 years, respectively, P = 0.15). CONCLUSIONS: In the present retrospective study of a clinical sample of mild and moderate myopic subjects, family history of myopia did not show predictive value for either the age of first prescription, or the final refractive error developed in adulthood.

Adult↗
PubMed1995

Myopia in teenagers. An eight-year follow-up study on myopia progression and risk factors.

UNLABELLED: A prospective 2-year study on myopia progression was commenced in 1984/85, with special attention to the rate of progression in a representative group of school children aged 9 to 12 years. A follow-up investigation of this group of myopic persons (now aged 17-20 years) was performed after 8 years, in order to describe the refractive error and possible risk factors for myopia progression over the period. The refractive error increased from -2.77 D to -5.14 D (mean values). PARAMETERS: age at début, degree of myopia, intraocular pressure, changes at the fundus, status of phoria, nearpoint of convergence and accommodation were all measured at the start and related to the refractive error measured 8 years later. No single parameter, apart from age at début, indicated that the individual would reach a high degree of myopia. The refractive error among the children with a début below 7 years of age was -6.60 D, but only -3.72 D among those with a début after 10 years. The change in refractive error over the 8-year period was not statistically related to the age at début, neither did the rate of progression depend on the degree of myopia, the changes at the fundus, nor the intraocular pressure. However, children could be found who had a high rate of progression, by using a combination of these parameters.

Accommodation, Ocular↗
PubMed1986

Myopia and diabetes mellitus with special reference to adult-onset myopia.

A significant preponderance of myopia has been reported in adult Danish diabetics as compared to non-diabetics. This suggestion of a special type of diabetic myopia is evaluated in the present study. Comparing myopia pattern (degree and age at onset) in diabetics and non-diabetics, 80 of each, the assessment is based mainly on personal information about refractive history, gained through interviews of patients referred from other departments for routine eye examination. With a concise memory as inclusion criterion, the resulting sample is hardly representative, and the significant findings are to be considered tendencies only. In the whole sample there were more cases of late myopia onset and progression than expected from textbooks; 31% were of adult onset, i.e. after the age of 20 year. Most late-onset cases were of a low order, a type more prevalent in diabetics (40%) than in the non-diabetic controls (22.5%). Otherwise there was no indication of a special type of diabetic myopia.

Adult↗
PubMedDate not supplied

Surgical correction of high myopia in phakic eyes with Worst-Fechner myopia intraocular lenses.

BACKGROUND: Implanting an anterior chamber intraocular lens in a phakic eye is an effective surgical procedure for the correction of high myopia. However, the potential risks on the anterior segment structures are not well-known. We conducted a prospective study to evaluate the effectiveness, predictability, and safety after Worst-Fechner lenses were implanted to correct high myopia. METHODS: We studied 32 eyes with preoperative myopia from -9.50 to -27.00 diopters (D) (-16.60 +/- 6.29 D). All 32 eyes were studied by clinical specular microscopy, and the endothelium was analyzed for cell density. Twenty eyes were additionally examined by fluorophotometry for lens transmittance changes. Thirty eyes were additionally examined using the flare mode of a laser flare cell photometer for anterior chamber inflammation; the patients were divided into three subgroups of ten eyes each according to when the postoperative flare measurements were done: 12 months, 18 months, and 24 months. Thirteen phakic eyes with myopia greater than -6.00 D were used as a control group for the flare study. The mean follow-up was 18.3 +/- 8 months (range 6 to 24 mo). RESULTS: Fifty-seven per cent of eyes (16 of 28) had an uncorrected visual acuity of 20/40 or better 12 months after surgery, and 58% (10 of 17 eyes) at 24 months. Spectacle-corrected visual acuity improved: 0.15 at 12 months and 0.16 at 24 months (0.1 = one line) from preoperative values. Visual acuity was stable after 3 months. Eighty per cent of eyes (25 of 31) at 6 months, 75% (21 of 28) at 12 months, and 76.5% (13 of 17) at 24 months had been correctly planned to within +/-1.00 D of emmetropia. The refractive results were stable 3 months after surgery. The mean endothelial cell loss was 7.2% at 3 months, 10.6% at 6 months, 13% at 12 months, and 17.6% at 24 months after surgery. The mean lens transmittance loss was 0.62% at 3 months, 0.72% at 6 months, 0.82% at 12 months, and 1.03% at 18 months after surgery. Flare values were significantly higher for eyes implanted with Worst-Fechner lenses than were those of the control group in all periods under consideration (Mann-Whitney test, p < 0.05). A decentration greater than 0.5 mm was present in 43% of eyes (14 of 32), and halos in 56% (18 of 32). In three eyes (9.3%), fixation of the lens to the iris was not stable. CONCLUSIONS: Our results for the Worst-Fechner myopia lens confirm earlier findings on the effectiveness of the refractive results. However, our study showed a continual decrease in endothelial cell density, a decrease in lens transmittance, and a chronic subclinical inflammation after the implantation of these lenses. Moreover, decentration was common, and the fixation of the IOL to the iris was not stable in some eyes.

Adult↗
PubMed2000

U.S. clinical investigation of the Artisan myopia lens for the correction of high myopia in phakic eyes. Report of the results of phases 1 and 2, and interim phase 3.

PURPOSE: The purpose of this article is to present the results of the U.S. Clinical investigation of the Artisan anterior chamber iris fixed lens implant for the correction of myopia in phakic eyes. METHODS: A prospective, multi-center, FDA-supervised trial was designed and undertaken in the United States by Ophtec USA, Inc., Boca Raton, Florida to determine the safety and efficacy of the Artisan lens as a potential refractive treatment for patients with high myopia. During the trial, two different models of the Artisan lens were used: one with a 5-mm optical zone (model 206) and the other with a 6-mm optical zone (model 204). RESULTS: The data presented comprise 176 enrolled subjects and 264 implant procedures. The most frequently chosen Artisan lens power was -13.00 D (average, -12.76 D; SD, 3.24). The postoperative results at 6 months for all eyes (n = 135) showed 100% of patients were 20/40 or better best-corrected while 72% gained one or more lines and 22% gained two or more lines regardless of degree of astigmatism or postoperative goal. Through the course of the study, intraocular pressure maintained a level with a mean below 16 mmHg. In general, total reported complications in the patient cohort decreased over time, dropping from 39% at the initial visit to 10% at visit four and 0% at visit seven. CONCLUSIONS: On the basis of the interim results of the U.S. Clinical Investigation of the Artisan Myopia Lens for the Correction of High Myopia in Phakic Eyes, the Artisan anterior chamber phakic IOL may offer an option for correction of high degrees of myopia. Refractive outcomes were exceptional and complications were minimal and amenable to treatment.

Adult↗
PubMed1993

Biomechanical considerations of high myopia: Part II--Biomechanical forces affecting high myopia.

Assuming the possibility of a scleral pathogenesis hypothesis for the development of high myopia, an examination of biomechanical forces affecting myopic eyes is presented. The biomechanical considerations include Laplace's law applied to the eye, balloon expansion dynamics, and the "porthole" effect derived from mechanical engineering principles. Other biomechanical considerations include Coleman's pressure head theory of accommodation, extraocular muscle stresses, and the role of uveoscleral outflow. Balloon expansion dynamics cast doubt on the common usage of Laplace's law governing fluid filled spheres for estimating coat stresses in myopia. Coleman's theory of accommodation, featuring an accommodation induced pressure head between the anterior and vitreous chambers is reanalyzed. Experimental testing of this hypothesis is still lacking. Uveoscleral outflow computations show that the vitreous chamber distension of high myopia may dramatically increase the importance of uveoscleral outflow in the pressure dynamics of high myopia. These biomechanical force phenomena clearly provide fertile ground for several areas of research that could illuminate the great puzzles of myopia.

Accommodation, Ocular↗
PubMed2005

Relationship of age, sex, and ethnicity with myopia progression and axial elongation in the correction of myopia evaluation trial.

OBJECTIVE: To identify the baseline factors independently related to 3-year myopia progression and axial elongation in COMET. METHODS: A total of 469 children were enrolled, randomly assigned to progressive addition lenses with a + 2.00 diopter (D) addition or to single vision lenses and observed for 3 years. Eligible children were 6 to 11 years old, with spherical equivalent myopia of - 1.25 to - 4.50 D, bilaterally. The primary and secondary outcomes, myopia progression by cycloplegic autorefraction and axial elongation by A-scan ultrasonography, were measured annually. Multiple linear regression was used to adjust for covariates, including treatment. RESULTS: Younger baseline age (6-7 vs 11 years, 8 vs 11 years, and 9 vs 11 years, P<.001; 10 vs 11 years, P = .04), female sex (P = .01), and each ethnic group compared with African Americans (Asian, P = .02; Hispanic, P = .002; mixed, P = .002; white, P = .001) were independently associated with faster 3-year progression. Children aged 6 to 7 years had the fastest progression of all age groups, progressing by a mean (+/- SD) of 1.31 D +/- 0.13 more than children aged 11 years. Females progressed 0.16 D more than the males. Children of mixed, Hispanic, Asian, and white ethnicity progressed more than African American children by 0.49 D +/- 0.16, 0.33 D +/- 0.11, 0.32 D +/- 0.13, 0.27 D +/- 0.08, respectively. Age and ethnicity, but not sex, were independently associated with axial elongation. Among these myopic children, a 0.5 mm increase in axial length was associated with 1 D of myopia progression. CONCLUSIONS: Younger baseline age was the strongest factor independently associated with faster myopic progression and greater axial elongation at 3 years. African American children had less myopic progression and axial elongation than the other ethnic groups.

Age Factors↗
PubMed2002

Undercorrection of myopia enhances rather than inhibits myopia progression.

The effect of myopic defocus on myopia progression was assessed in a two-year prospective study on 94 myopes aged 9-14 years, randomly allocated to an undercorrected group or a fully corrected control group. The 47 experimental subjects were blurred by approximately +0.75 D (blurring VA to 6/12), while the controls were fully corrected. Undercorrection produced more rapid myopia progression and axial elongation (ANOVA, F(1,374)=14.32, p<0.01). Contrary to animal studies, myopic defocus speeds up myopia development in already myopic humans. Myopia could be caused by a failure to detect the direction of defocus rather than by a mechanism exhibiting a zero-point error.

Adolescent↗
PubMed1980

[Documents on the origins of myopia. Fourth communication: Cause of myopia and some new perspectives in prevention and treatment (author's transl)].

The author's study of the literature and his own investigations have led him to develop a new theory of the origins of myopia. There are three principal causal factors: 1. close-range vision--weakened accommodation; 2. hereditary conditions; 3. weakened sclera--intraocular pressure. Even at the onset of development of myopia there is a complex interaction between the first two factors, which are involved more or less deeply. The third factor, the weakened sclera, only makes itself felt in more advanced stages of myopia. Two possibilities for prophylaxis and treatment may be inferred from these theories of the pathogenesis of myopia, namely influencing accommodation and surgical measures to strengthen the posterior pole. In addition, it is now possible to evaluate and apply some traditional treatment methods correctly.

Accommodation, Ocular↗