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PubMed1993

Three-year changes in refraction and its components in youth-onset and early adult-onset myopia.

We compared refractive components, and their changes during a 3-year period, for 79 young adults of whom 29 were youth-onset myopes, 26 were early adult-onset myopes, and 24 were emmetropes. In the initial evaluation we found that mean corneal power was greater for both groups of myopes than for the emmetropes, whereas mean vitreous chamber depth and mean axial length were greater for the youth-onset myopes than for the other two refractive error groups. However, the differences between the two groups of myopes appear to be related to the fact that the mean amount of myopia was significantly greater for the youth-onset myopes than for the early adult-onset myopes. During the 3-year period, mean spherical equivalent refraction for subjects in all three refractive error groups changed in the direction of increasing myopia. For each of the three groups, the only refractive component changes having significant correlations with changes in refraction were vitreous chamber depth and axial length. We interpret these results as indicating that: (1) whether axial elongation occurs before, during, or after the completion of the normal growth period, the result is an eye whose cornea is significantly steeper, whose vitreous chamber depth and axial length are significantly greater, and whose lens differs little from that of an emmetropic eye of a person of the same age and (2) when myopia progresses with time, the progression is due to an increase in axial length that is not fully compensated by a decrease in lens power.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Reported myopia in opposite sex twins: a hormonal hypothesis.

Two studies have reported poor vision in opposite sex twins (evidenced by wearing glasses or low visual acuity, both of which are interpreted here as evidence of myopia), whereas none have reported an absence of such effects. If these reports are replicable, it would suggest a hormonal effect. There is one report of higher testosterone levels in those suffering from high myopia. A possible mechanism would be if sex hormones in opposite sex pairs transfer from one fetus to the other. There is evidence that sex hormones can cross the placenta, and reports of sex differences in the development of opposite sex twins are consistent with such transfers. If different parts of the eye respond differentially to sex hormones, eyes developing in the unusual hormonal environment of opposite sex twins would be expected to have high myopia rates.

Diseases in Twins↗
PubMed1996

Changes in myopia, visual acuity, and psychological distress after biofeedback visual training.

The effects of auditory biofeedback training on myopia, visual acuity (VA), and psychological distress were evaluated in a controlled prospective study involving 55 mildly myopic (< or = -3.5 D) high school students. These myopes were divided into 2 groups, matched for age and dioptric defect: 33 were treated with visual training and 22 were not; 27 emmetropic subjects formed a further control group. Subjects were evaluated at the baseline (T0), at 10 weeks after the end of the treatment (T1), and after an interval of 12 months (T2) from the baseline for: (1) manifest and cycloplegic refraction, and the difference between them (cycloplegic tonus); (2) VA measured with a conventional optotype in all subjects, and also with a computer-generated optotype in the treated group; and (3) psychometric values and personality profile. At T2, myopia had significantly worsened both in the treated and in the control myopes; VA in the treated myopes appeared significantly improved when measured by the conventional optotype, but unchanged when measured by computer. Psychometric scores improved significantly in the treated myopes and in the emmetropic controls. Objectively the autorefractometer showed that 38% of the myopes had voluntary control of positive accommodation, i.e., the ability to increase spherical defect; no voluntary control of negative accommodation was observed. An increase in VA was associated with a significant increase in the foveation time (i.e., the period of time when the target is imaged on the fovea and the eye is motionless), and was partly attributable to a learning effect. In conclusion, biofeedback visual training had a positive effect on psychological distress and subjective VA improvement, but failed to reduce the existing myopia or delay its evolution.

Adolescent↗
PubMed1996

Do variations in normal nutrition play a role in the development of myopia?

BACKGROUND: A number of papers have reported an association between diet and myopia; however, these studies have generally considered the diet of children already myopic. This study compared the nutritional intake and some simple body measurements for a group of children who subsequently became myopic with that of a group who did not become myopic. METHODS: The nutritional data for 24 subjects who developed myopia between the ages of 7 and 10 years were compared with data for 68 subjects who were still not myopic at the age of 10 years. RESULTS: Children who developed myopia had a generally lower intake of many of the food components than children who did not become myopic. The differences were statistically significant for energy intake, protein, fat, vitamins B1, B2 and C, phosphorus, iron, and cholesterol. Despite these differences, children who became myopic were neither shorter nor lighter, at the age of 7 years, than children who did not become myopic. CONCLUSIONS: There is no evidence that the incident myopes were in any way undernourished and it therefore seems that their energy requirements were less than those of the control subjects.

Anthropometry↗
PubMed1998

Accommodation and pupillary response in early-onset myopia among schoolchildren.

PURPOSE: To investigate changes in accommodation and pupillary reaction in early-onset myopia among children. METHODS: An objective infrared optometer and a pupillometer were used to evaluate simultaneously tonic accommodation, accommodative response, accommodative adaptation, and pupil diameter in 19 schoolchildren with early-onset myopia and 15 age-matched emmetropic controls. RESULTS: Tonic accommodation in the early-onset myopes (1.03 D) was significantly less than in the emmetropes (1.37 D) (p < 0.05), whereas accommodative response and accommodative adaptation showed no significant difference between the early-onset myopes and emmetropes. The average pupil diameter after 20 min of dark adaptation in the early-onset myopes was 4.52 mm, which was significantly smaller than that in the emmetropes (5.21 mm) (p < 0.05). During nearwork stimulation, the average pupil diameter further decreased to 3.83 mm in the early-onset myopes and 4.78 mm in the emmetropes (p = 0.003). CONCLUSION: These results suggest that low tonic accommodation and small pupil diameter may play important roles in the pathogenesis of early-onset myopia among schoolchildren.

Accommodation, Ocular↗
PubMed2002

Is esophoria a factor in slowing of myopia by progressive lenses?

PURPOSE: Our previous findings suggest that myopia can be slowed by wearing progressive lenses, and one possible mechanism for this is through the oculomotor system. We reanalyzed our findings to investigate the relationship between baseline oculomotor parameters and change in refraction, and between the change in these values and change in refraction. METHODS: Children who wore progressive lenses (N = 38; 26 with +1.50 D addition, and 16 with +2.00 D addition) or single-vision lenses (N = 32) had refraction, distance heterophoria, near heterophoria, and stimulus AC/A ratio measured prospectively over a 2-year period. RESULTS: There were no statistically significant correlations between baseline heterophoria or AC/A values and change in refractive error. Distance and near heterophoria did not change significantly over the 2 years of the experiment; AC/A ratio decreased significantly, but in an equivalent manner for both groups. In the combined progressive lens group, change toward more exophoria at near was associated with less myopia progression. However three-way analysis of variance (visit x lens type x esophoria/nonesophoria) showed significant main effects in refraction over all five visits. There was a significant interaction between lens type and visits; there was no significant interaction between lens type and esophoria/ nonesophoria grouping. Three-way analysis of variance showed a statistically significant decrease of AC/A ratio over all five visits; there was no interaction of visit by lens or visit by phoria grouping. CONCLUSIONS: Although there were no statistically significant differences between esophoric and nonesophoric subjects, there was only 46% as much myopia progression in the progressive lenses-esophoric group as in the progressive lenses-nonesophoric group. In addition, there were no differences in AC/A ratio between esophoric and nonesophoric subjects. However these findings are not definitive. This experiment was not designed to discriminate between refraction and oculomotor changes in esophoric and nonesophoric subjects and lacked the necessary statistical power to do so.

Analysis of Variance↗
PubMed2004

Measurement of refractive state and deprivation myopia in two strains of mice.

PURPOSE: The mouse eye has a bright retinal image (f/number <1) but low optical quality (visual acuity about 0.5 cpd) that may render emmetropization unnecessary. However, this species is potentially a powerful model to study eye growth and myopia because its genome can be readily manipulated and has been completely sequenced. We have investigated how precisely eyes of mice can be refracted and tested whether deprivation myopia can be induced by frosted diffusers. METHODS: An automated eccentric infrared photorefractor was adapted to refract eyes of two mouse strains--C57BL/6 (B6) and DBA/2 (D2)--during Tropicamide cycloplegia without anesthesia. Axial lengths were measured in highly magnified video images of freshly excised eyes. Plastic hemispherical diffusers were applied between postnatal days and 29 and left attached for 7 or 14 days. RESULTS: (1) Trial lenses ranging from +10 to -10 D produced high correlations between the brightness slope in the pupil and applied lens power (r = 0.81 and r = 0.87), demonstrating reliable refraction. Five repeated measures in 12 eyes showed an average standard deviation of 3.0 D, equivalent to an axial length change <10 microm (derived from schematic eye modeling). (2) Deprivation produced a significant shift toward myopia, relative to untreated eyes, but only after 14 days and only in B6 mice (p = 0.02 with or p = 0.00038 without one outlier; N = 9). In contrast, DBA/2J were unaffected by occlusion, perhaps due to mutations that target eye, lens, or anterior segment. (3) Both eyes of untreated animals often had axial lengths that differed markedly. Surprisingly, we detected no significant correlation between refractive error and axial length after treatment. CONCLUSIONS: The infrared refraction technique is sufficiently sensitive to resolve equivalent changes in axial length of only +/- 10 microm in alert mice. Prolonged occlusion produces a significant myopic shift in B6 mice, but not in D2 mice. Even among isogenic B6 mice, the response is variable for reasons that presumably trace back to subtle developmental, environmental, and technical factors.

Animals↗
PubMed1986

Drug-induced acute transient myopia with retinal folds.

A patient was seen with acute bilateral transient myopia, shallowing of the anterior chamber, and radiating perimacular folds. This was believed to be a drug reaction. A fluorescein angiogram was performed which showed no retinal edema. A number of pathophysiologic mechanisms have been proposed for acute transient myopia, but the findings in this patient support ciliary body swelling as the cause of the changes in the eye. This swelling of the ciliary body results in a forward rotation of the lens-iris diaphragm and the vitreous, which causes both the myopia and the retinal folds.

Acetaminophen↗
PubMed1992

Retinal detachment after refractive surgery for myopia.

Refractive surgery has been used widely in some countries for the last 20 years for the correction of myopia. Radial keratotomy and keratomileusis, the most common procedures, may concur with retinal detachment. A total of 14 eyes in 12 patients, 7 after keratomileusis and 7 after radial keratotomy, which had either asymptomatic or symptomatic retinal breaks, subclinical and clinical rhegmatogenous retinal detachments, or both, are discussed here. Five eyes were treated with either laser photocoagulation or cryopexy alone, seven eyes with a scleral buckling procedure, one eye with vitrectomy, and one eye was not operated on. At the final follow-up examination, anatomic reattachment had been achieved in 12 of 14 eyes (85.7%). Visual acuity improved in 3 eyes (21.4%), remained stable in 9 eyes (64.3%), and was worse in 2 eyes (14.3%). The scleral buckling procedures used in the repair of retinal detachment induced refractive changes by modifying axial length and corneal curvature, with recurrence of myopia and astigmatism. Myopia increased a mean of -3.00 diopters in 6 of 7 eyes (86%). Myopic astigmatism power changed a mean of -1.00 diopter in 5 eyes (71%), and the astigmatic axes shifted in 3 eyes (43%). This situation could be prevented with an early peripheral search for and treatment of peripheral retinal degenerative pathologic changes, by avoiding encircling bucklings, or by using alternative methods of treatment.

Adult↗
PubMed2002

Imaging analysis with optical coherence tomography: relevance for submacular surgery in high myopia and in multifocal choroiditis.

PURPOSE: To classify the preoperative and postoperative optical coherence tomography (OCT) findings for subfoveal choroidal neovascularization (CNV) related to high myopia and multifocal choroiditis (MFC) and to correlate these findings with surgical outcome. METHODS: Ten consecutive patients presenting with subfoveal CNV related to either MFC or degenerative myopia were evaluated. Each patient underwent a biomicroscopic examination, fluorescein and indocyanine green angiographies, as well as OCT before and after surgical removal of CNV. Four different parameters were considered in the analysis of all OCT scans: tissue reflectivity, location of the CNV band, presence or absence of a separation zone, and reflectivity underneath the retinal pigment epithelium (RPE) band. RESULTS: For all six eyes with MFC, OCT showed a hyperreflective band anterior to the RPE with a separation zone and an optically clear zone underneath the RPE. Visual acuity improved in all six eyes. For the degenerative myopia group (4 eyes), OCT revealed findings similar to those observed for MFC for 1 eye, which had a favorable postoperative outcome. The remaining three myopic eyes with different OCT patterns had poor postoperative outcomes. CONCLUSION: Optical coherence tomography can provide preoperative clues for submacular surgery. Eyes with CNV located anterior to and separated from the RPE that have an "optically clear zone" underneath are the best candidates for surgical removal. Such a feature was correlated with a good postoperative outcome.

Adolescent↗
PubMed2006

High prevalence of myopia in Japanese patients with idiopathic focal subretinal neovascularization.

PURPOSE: To determine whether myopia is more prevalent in Japanese patients with idiopathic focal subretinal neovascularization (IFSN) than in normal control subjects. METHODS: Forty-seven eyes of 46 patients with an initial diagnosis of IFSN and 291 eyes of 291 controls were studied. Refractive errors were measured with an autorefractometer, and the spherical equivalent of the refractive error was used for the statistical analyses. All patients had undergone fluorescein angiography (FA) to confirm the presence of the choroidal neovascularization. In addition, indocyanine green angiography (ICGA) had been performed to determine whether chorioretinal atrophy and breaks of Bruch's membrane, which are consistent with myopic retinopathy, were present. RESULTS: The mean age of the patients in the control group was not significantly different from that of patients in the IFSN group. The mean spherical equivalent of the refractive errors was -2.62 +/- 2.70 diopters (D) in the control group and -5.24 +/- 3.41 D in the IFSN group (P = 0.00005). The incidence of high myopia was significantly higher in the IFSN group (41.3%) than in the control group (12.0%, P < 0.0001). FA and ICGA showed no chorioretinal atrophy and lacquer cracks, thus confirming that patients with myopic retinopathy were excluded from the IFSN group. During the mean follow-up period (44.7 months), myopic retinopathy did not develop in any of the eyes in the IFSN group. CONCLUSION: Japanese patients with IFSN were highly myopic, suggesting that myopia may play a role in the development of choroidal neovascularization in IFSN patients.

Adolescent↗
PubMed2005

Refractive lens exchange for myopia: a new perspective?

PURPOSE OF REVIEW: Although lens surgery for high myopia has a long History, it has been extremely controversial. Colin's study of 1999 indicated a much higher than expected rate of retinal detachment. The purpose of this review is to reassess the place of refractive lens exchange in high myopia in the light of more recent reports in the literature and a more critical examination of Colin's data. RECENT FINDINGS: A meta analysis of papers on refractive lens exchange and cataract in high myopia between 1996 and 2004 included some 2036 eyes. The mean follow up was 43.5 months and overall incidence of retinal detachment was 1.85%. This is only slightly different from that expected in the highly myopic population as reported by Burton at 1.5%. The recent reports in 2003 of Ravalico et al. and Guell et al., with 4 year follow up, show only 1 detachment for 422 eyes. Further Colin's study had a group very high in risk factors having a low incidence of posterior detachment and 30% pre-existing retinal lesions. SUMMARY: Modern surgical techniques, IOLs and choosing the appropriate group to whom this procedure should be offered should lead to it becoming an accepted, safe and common refractive operation.

Humans↗
PubMed2006

Optical coherence tomography after photodynamic therapy for patients with pathologic myopia.

PURPOSE: To evaluate early changes after photodynamic therapy (PDT) for patients with subfoveal choroidal neovascularization (CNV) due to pathologic myopia by optical coherence tomography (OCT). METHODS: PDT was performed on 10 eyes of 10 patients who presented with subfoveal CNV due to pathologic myopia. OCT was used to evaluate changes 1 day, 3 days, and 7 days after therapy. Changes in intraretinal and subretinal fluid and CNV were examined on the images obtained. The retinal elevation and the height of the neurosensory retinal detachment were calculated. From these two values, the thickness of the neurosensory retina was obtained. The thickness of the neurosensory retina was measured to ascertain the intraretinal fluid change, and the height of the neurosensory retinal detachment was measured to ascertain the subretinal fluid change. RESULTS: The mean pretherapy retinal elevation+/-SD increased from 211+/-28 microm to 230+/-39 microm 1 day after PDT and decreased to 221+/-36 microm 3 days after therapy. At 7 days after therapy, the mean retinal elevation+/-SD was 211+/-22 microm. The retinal elevation was due to a subretinal fluid accumulation, whereas the thickness of the neurosensory retina increased only to a minor extent (range, 0-22 microm) and the foveal architecture remained unchanged. The mean pretherapy height+/-SD of the neurosensory retinal detachment was 6+/-11 microm. It was 18+/-20 microm, 12+/-12 microm, and 3+/-6 microm 1 day, 3 days, and 7 days after therapy, respectively. No change in CNV was observed during follow-up. CONCLUSION: The results of our study indicate that the acute infiltration observed in patients with pathologic myopia after PDT occurs in the first day and regresses during the first week. Yet, it should be noted that, unlike in patients with age-related macular degeneration, the acute infiltration phase can be observed by OCT only to a limited extent.

Adult↗
PubMed2004

Study design issues in a corneal reshaping contact lens myopia progression study.

Advances in contact lens design have led to corneal reshaping contact lenses that can be worn at night to temporarily reduce myopia so that patients can see clearly without glasses or contact lenses. Children are able to wear corneal reshaping contact lenses, but we do not know how they may affect the progression of myopia. A myopia control study with corneal reshaping contact lenses poses study design problems that other studies do not encounter because they temporarily reduce the refractive error. A discussion of the choice of primary outcome and control group will highlight some of these unique study design issues.

Contact Lenses↗
PubMed2006

Higher order aberrations induced by soft contact lenses in normal eyes with myopia.

PURPOSE: To evaluate and compare the wavefront characteristics of normal eyes with and without hydrogel soft contact lenses for correction of myopia. METHODS: Higher order aberrations (HOA) of 30 eyes of 15 soft contact lens users who had no ocular diseases other than myopia were quantified with a Nidek Marco three dimensional Wave wavefront analyzer. Zernike's polynomial was used to describe the wavefront measurements. Root mean square (RMS) values of the total HOAs, total coma, total trefoil and total spherical aberrations were obtained in the same eyes with and without soft contact lenses. We used paired sample t-test to analyze the data. RESULTS: Mean RMS values for all higher order aberration components with and without soft contact lenses were: total HOA 0.364 +/- 0.129 microm without lenses and 0.456 +/- 0.175 microm with lenses (P = 0.01), total coma 0.203 +/- 0.095 microm without lenses and 0.220 +/- 0.133 microm with lenses (P = 0.51), total trefoil 0.193 +/- 0.074 microm without lenses and 0.254 +/- 0.153 microm with lenses (P = 0.06), total spherical aberration 0.126 +/- 0.121 microm without lenses and 0.148 +/- 0.095 microm with lenses (P = 0.36). CONCLUSIONS: Wavefront analysis showed soft contact lenses for myopia induced a significant increase in total HOA. Though total coma, trefoil and spherical aberrations were also higher with contact lenses they were not statistically significant when individually evaluated and compared to values without contact lenses.

Astigmatism↗
PubMed2004

Characteristics of corneal ectasia after LASIK for myopia.

PURPOSE: There are numerous reports of corneal ectasia after laser in situ keratomileusis (LASIK) for myopia without a consistent definition of this condition or a definitive etiology. We conducted a retrospective analysis of published case reports to describe common characteristics of this postoperative event and compared them with findings from a group of successful LASIK patients. METHODS: A MEDLINE search for "LASIK" and "ectasia" yielded 21 relevant articles published before May 2003 (n = 86 eyes, 59 patients). A comparison group (n = 103 eyes, 63 patients) was selected from a clinic-based sample of successful LASIK patients with 12 months of follow-up after treatment. Descriptive statistics are reported as median and interquartile range. Comparisons were performed using the Wilcoxon rank sum, Wilcoxon signed rank, and chi-square tests. RESULTS: Time to diagnosis of ectasia after LASIK was 13 months (6 to 20 months). Residual myopia in the ectasia group was -3.69 D (-6.00 to -2.13 D) and was significantly greater than the comparison group, -0.38 D (-0.75 to 0.00 D), P < 0.001. After surgery, eyes with ectasia had increased corneal toricity 2.87 D (2.00 to 4.9 D) with increased oblique astigmatism 1.3 D (0.23 to 2.89 D) relative to eyes in the comparison group 0.00 D (0.00 to 0.08 D), and a loss of 2 lines (-0.5 to -6 lines) of best spectacle-corrected visual acuity (all P < 0.001). Thirty-five percent of reported cases resulted in subsequent corneal transplantation. CONCLUSIONS: Preoperative characteristics of corneal ectasia include worse visual acuity, less corneal thickness, greater residual myopia, and greater corneal toricity than nonectatic eyes. Treatment factors associated with corneal ectasia after LASIK are greater stromal ablation and less residual stromal bed thickness. Postoperative characteristics of corneal ectasia are myopic refractive error with increased astigmatism, worse spectacle-corrected visual acuity, increased corneal toricity with topographic abnormality, and progressive corneal thinning.

Adult↗
PubMed2005

Prevalence and characteristics of peripheral retinal degeneration in Chinese adults with high myopia: a cross-sectional prevalence survey.

PURPOSE: The purpose of this study was to study the prevalence of peripheral retinal findings in adult Chinese patients with high myopia (refraction < or = -6.00 D) and to investigate the correlation between the retinal lesions and the severity of myopia or axial length. METHODS: A cross-sectional prevalence survey screening was conducted in high ethnic Chinese myopes with refractions equal to or less than -6.00 D. The examinations included cycloplegic refraction, A and B scan ultrasonography, and retinal examinations by indirect ophthalmoscopy with scleral indentation and Goldmann three-mirror contact lens examination. RESULTS: Two hundred thirteen eyes in 213 patients with a mean refraction of -10.10 +/- 4.23 D (range = -6.00 to -27.00 D) were examined. The mean axial length was 26.69 +/- 1.68 mm (range = 25.18-33.62 mm) and the mean age was 33.5 +/- 10.6 years (range = 18-73 years). The most common peripheral retinal finding was pigmentary degeneration (51.2%), followed by lattice degeneration in 12.2% and retinal holes in 7.5% of eyes. A positive correlation was noted between axial length and the lesions of pigmentary degeneration and pavingstone degeneration. The prevalence of retinal holes was 6.4% and 30.0% in eyes with axial length of < 30 mm and > or = 30 mm, respectively (chi-squared test, p = 0.006). CONCLUSION: A high prevalence of peripheral retinal degenerations was found in adult Chinese high myopes. The presence of retinal holes was positively correlated with very high myopia of an axial length of > or = 30 mm.

Adult↗
PubMed2006

Surgical strategy in the treatment of globe protrusion depending on its mechanism (Graves' disease, nonsyndromic exorbitism, or high myopia).

BACKGROUND: Graves' ophthalmopathy affects orbital contents and eyelids. Protrusion of the globe can also be the result of myopia and/or an abnormal orbit shape, which is responsible for nonsyndromic exorbitism. It is necessary to recognize these components of protrusion to treat patients adequately. The authors present a surgical strategy for treatment of the orbit and lids. METHODS: Files of 84 patients treated from 1984 to 2003 were retrospectively reviewed. Sixty-eight patients were operated on for Graves' ophthalmopathy and 16 for nonsyndromic exorbitism with or without myopia. The surgical strategy was adapted to the degree of emergency, the age of the patient, and the shape of the orbit measured using computed tomography. The accepted standard of treatment was a coronal approach with a two-wall expansion, with or without bone grafts, especially in cases of associated nonsyndromic exorbitism, with or without complementary ablation of the external part of the orbital floor. Lid surgery was performed at a second stage. RESULTS: Nonsyndromic exorbitism patients were successfully treated in one step. No diplopia was present either preoperatively or postoperatively. In contrast, the treatment of the Graves' ophthalmopathy patients justified one to three orbital expansion procedures per patient and/or one to seven procedures for levator palpebrae lengthening or reinsertion. Forty-three percent of preexisting diplopias were improved by the surgery. The overall postoperative incidence of de novo diplopia was 19 percent. In the Graves' ophthalmopathy series, three patients (5 percent) finally underwent strabismus surgery. No major complication occurred. CONCLUSIONS: The treatment of Graves' ophthalmopathy is challenging. A graded approach is justified. Patients have to be informed that several procedures may be necessary and, in cases of nonsyndromic exorbitism or myopia, that facial modifications might occur.

Algorithms↗