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PubMed2001

Further refinement of the MYP2 locus for autosomal dominant high myopia by linkage disequilibrium analysis.

INTRODUCTION: High myopia (>-6.00 diopters) is a complex common disorder that predisposes individuals to retinal detachment, glaucoma, macular degeneration, and premature cataracts. A recent linkage analysis of seven families with autosomal dominant high myopia has identified one locus (MYP2) for high myopia on chromosome 18p11.31 (Young et al.: Am J Hum Genet 1998;63:109-119). Haplotype analysis revealed an initial interval of 7.6 centimorgans (cM). METHODS: Transmission disequilibrium tests (TDT) with both the Statistical Analysis for Genetic Epidemiology (SAGE) 3.1 TDTEX and GENEHUNTER 2 (GH2) programs were performed using chromosome 18p marker alleles for this interval. RESULTS: Using SAGE analysis, the following p values were obtained for markers in marker order in this region: D18S1146 (p = 0.227), D18S481 (p = 0.001), D18S63 (p = 0.062), D18S1138 (p = 0.0004), D18S52 (p = 1.79 x 10(-6)), and D18S62 (p = 0.141). GH2 TDT analysis revealed the following p values for the best allele for the markers: D18S1146 (p = 0.083), D18S481 (p = 0.108), D18S63 (p = 0.034), D18S1138 (p = 0.011), D18S52 (p = 0.007), and D18S62 (p = 0.479). CONCLUSION: These data suggest that the gene for 18p11.31-linked high myopia is most proximal to marker D18S52, with a likely interval of 0.8 cM between markers D18S63 and D18S52. Due to the contraction of the interval size by TDT, these results provide a basis for focused positional cloning and candidate gene analysis at the MYP2 locus.

Chromosomes, Human, Pair 18↗
PubMed1991

Three avian eye enlargement protocols as myopia models: effects of pharmacological intervention.

Myopia is a prevalent condition threatening vision in half or more of the individuals in some subpopulations and at some ages. The etiology is unknown. It is not even clear whether myopia has several possible causes or only one, whether the condition is inherited or acquired. Suggested counter measures have ranged from behavior modification during the growing years through various medications, to surgical intervention. It is suggested that answers to these questions must lie in research exploring how the eye develops, how it serves its owner. A common finding in most cases of myopia is that the eyeball is too long axially, thus the image from a distant object comes to sharp focus in front of, rather than at, the retina. Accommodation increases the refractive power of the eye and is counterproductive in a myope. Nonetheless, one suggested treatment has been to suppress accommodation by paralyzing the ciliary muscles. Another theory suggests that high intraocular pressure causes eye enlargement, thus the anti-glaucoma drugs have sometimes been recommended. We report here some trials involving drugs given to chicks with light-induced avian glaucoma, a syndrome characterized by moderate to severe myopia, and elevated intraocular pressure.

Animals↗
PubMed2006

Prevention of myopia progression with 0.05% atropine solution.

AIM: The aim of this study was to evaluate the efficacy of 0.05% atropine solution for controlling myopia progression in school-aged children. RESULTS: This retrospective, case-control study enrolled myopic school-aged children who had presented at Kaohsiung Chang Gung Memorial Hospital (Kaohsiung, Taiwan) from 2001 to 2004. A group of 57 children (30 boys, 27 girls; 6-12 years of age) with regular follow-up was divided into a subgroup of 21 children (12 boys, 9 girls) who received atropine eyedrops (0.05%) every evening, and a subgroup of 36 children (18 boys, 18 girls), who remained untreated, served as controls. The changes in refractive status of 114 eyes in 57 children were collected and compared for patients treated with 0.05% atropine eyedrop and those without medical control. The initial spherical equivalent of refractive status range was between -0.5 and -5.5 D. Mean myopia progression for the group of patients treated with 0.05% atropine eyedrop (n = 21) was -0.28 +/- 0.26 D/year, significantly lower than that of the control group of -0.75 +/- 0.35 D/year (36 patients; P < 0.001). The 0.05% atropine group had a significant lower ratio of uncontrolled myopia, that progressed greater than -0.50 D in 1 year, relative to the controls (16.7% versus 77.8%; P < 0.001). CONCLUSIONS: The results of this study demonstrate that, with regular instillation, topical 0.05% atropine is an effective agent for controlling myopia progression in a majority of school-aged children for at least a period of 1 year.

Atropine↗
PubMed1978

Biofeedback of accommodation to reduce functional myopia: a case report.

A 30-yr-old man received biofeedback training of his accommodation to reduce his functional myopia. There were seven training sessions for a total time of 34 min. Each training session consisted of a baseline-level recording period followed by a feedback period, a second baseline-level recording period, and then a second feedback period. Reduction of the functional myopia was learned within a few minutes. Since the training was conducted in a dark environment, myopia reduction was not expected in an illuminated environment. Nonetheless, some generalization was demonstrated with a reduction in the subjective measures of myopia (about 1 D for the right eye, 0.50 D for the left eye) and improvement in unaided visual acuity (from about 20/50 to 20/30 for each eye).

Accommodation, Ocular↗
PubMed1982

Environmental factors in the epidemiology of malignant myopia.

Malignant myopia is a major cause of blindness, yet compared with cataract, glaucoma, or diabetic retinopathy, this condition has received little attention from clinical investigators. This study explores existing health and geophysical records in search of clues that might suggest directions for further research into the etiology of blinding myopia. From the environmental data available for analysis, annual hours of sunshine emerged as the factor with the strongest (inverse) association with malignant myopia. Using data from the 14-state Model Reporting Area for Blindness, a case-referent study of this factor revealed both sex and age-birth year modifications of this effect. Relatively more blindness due to malignant myopia occurred among women in low sunshine regions and among men in high sunshine regions. The effect among women appeared during middle age (45 +, or born before 1926) but among men was not seen until later (age 65 + or born before 1906).

Adult↗
PubMed1987

Meridional corneal components of myopia progression in young adults and children.

Records were selected from a data pool of myopic private practice patients to study the relation of refractive error change and keratometer power change in young adulthood. Selection was on the basis of three or more refractions and keratometer readings at and/or after 18 years of age. There were significant correlations between rate of myopia progression and rate of keratometer power change. Linear regression slopes of rate of refractive error change on rate of keratometer power change were in the neighborhood of 0.7. These findings were in contrast to the lack of correlation between myopia increase and corneal steepening in childhood myopia progression. Young adulthood myopia progression also appeared to be accompanied by a slight tendency toward a with-the-rule astigmatic shift.

Adolescent↗
PubMed1987

A review and a suggested classification system for myopia on the basis of age-related prevalence and age of onset.

Systems for the classification of myopia are usually based on etiological dichotomies such as hereditary vs. environmental, physiological vs. pathological, structural vs. functional, or axial vs. refractive. The purpose of this paper is to propose a system for the classification of myopia based not on assumed etiological factors but on readily available and easily verifiable information, including age-related prevalence and age of onset. The proposed system classifies myopia into four categories: congenital, youth-onset, early adult-onset, and late adult-onset. Paradoxically, such a classification, being devoid of etiological assumptions, may help to make possible a better understanding of the etiology of the various categories of myopia.

Adolescent↗
PubMed1989

Myopia: what can we do about it clinically?

Methods that have been used by vision practitioners for the control of myopia include visual training, biofeedback training, undercorrection, overcorrection, the use of bifocal lenses, the use of contact lenses, the instillation of atropine, and refractive surgery. With some exceptions the use of these methods has achieved only limited success. The lack of success with the less-invasive methods--which are based on the supposition that myopia is caused by accommodation--may be due to the fact that they are used for eyes that are already myopic and therefore have already undergone axial elongation and scleral stretching. If it were possible to predict which children were at risk for the development of myopia, vision practitioners would be able to institute procedures for the control of myopia when only a minimum of scleral stretching has occurred. Risk factors that warrant investigation include the axial length/corneal radius ratio and the resting state of accommodation.

Accommodation, Ocular↗
PubMed1991

Rigid gas-permeable contact lenses for myopia control: effects of discontinuation of lens wear.

Conventionally fitted Paraperm O2plus contact lenses were worn for 44 months by 23 myopic children, who discontinued lens wear for 2.5 months and then resumed lens wear with Fluoroperm 30 lenses for a period of 8 months. Mean changes in myopia were: (1) an increase of 0.76 D during the initial 44 months of lens wear, (2) a further increase of 0.27 D during the 2.5 months when lenses were not worn, and (3) a decrease of 0.02 D during the 8-month period of Fluoroperm 30 lens wear. These results show that the effect of rigid gas-permeable lenses on myopia progression is diminished if lens wear is discontinued; however, the mean increase in myopia for these children was significantly less than would have been expected if glasses had been worn for the entire 54.5-month period. The results after discontinuation and then resumption of lens wear show that the effect of contact lenses in controlling the progression of myopia could not be accounted for entirely on the basis of corneal flattening as measured by the keratometer, therefore reinforcing the conclusion that corneal flattening due to rigid lens wear takes place primarily at the corneal apex, rather than in the zone of the cornea measured by the keratometer.

Adolescent↗
PubMed2001

The contact lens and myopia progression (CLAMP) study: design and baseline data.

BACKGROUND: Although previous contact lens myopia control studies indicate that rigid contact lenses slow the progression of myopia in children, they have all suffered from limitations that challenge the significance of their results. The Contact Lens and Myopia Progression (CLAMP) Study addresses the limitations of previous studies and attempts to correct them by implementing alternative Study designs. The CLAMP study also measures all the ocular components to examine the potential mechanism of treatment effect. METHODS: Eligible children were fitted with rigid gas-permeable contact lenses and enrolled in a run-in period to determine whether they were able to adapt to rigid contact lens wear. Subjects who successfully completed the run-in period were randomly assigned to wear rigid contact lenses or soft contact lenses for the remainder of the 3-year study. The primary outcome measure will be the 3-year change in cycloplegic autorefraction; the secondary outcome measures will include the 3-year change in axial length, peripheral autorefraction, crystalline lens curvatures, corneal curvature and thickness, accommodation, and intraocular pressure, which are being measured annually. RESULTS: We examined 148 eligible subjects who participated in the run-in period. Of the 148 eligible subjects, 116 (78.4%) were able to adapt to rigid contact lens wear and were enrolled in the CLAMP Study. The mean age of the participants at the baseline visit was 10.5 years, and 59.5% were girls. At the randomization visit, the mean (+/-SD) spherical equivalent refractive error in the right eye was -2.09 +/- 0.89 D, the mean central curvature of the right cornea by videokeratography was 44.5 +/- 1.3 D, and the mean axial length of the right eye was 24.13 +/- 0.71 mm. CONCLUSIONS: Four of five children aged 8- to 11-years-old were able to adapt to rigid gas-permeable contact lens wear. The CLAMP Study aims to further clarify the effect of rigid gas-permeable contact lenses on myopia progression in children.

Astigmatism↗
PubMed2004

Development and validation of a multidimensional quality-of-life scale for myopia.

BACKGROUND: Five dimensions of health-related quality of life in myopia were hypothesized to affect satisfaction with visual correction modality. Items on these dimensions reflected the frequency of visual compromise and ocular symptoms; individual tolerance of these compromises and symptoms; cosmesis; psychological constructs (including situation-dependent characteristics such as adaptability, self-efficacy, and subjective well-being); and personality traits such as extraversion and introversion. METHODS: Psychologically oriented items and visually oriented items were developed in two stages involving 1,647 participants. Item development was based on a comprehensive literature review, interviews with experts, myopic subjects, and graduate students, and written feedback. Items were selected through factor analysis and the examination of their ability to discriminate between treatment conditions (spectacle wear, daily use of contact lenses, continuous use of contact lenses, or laser-assisted in-situ keratomileusis for myopia). After development, selection, and validation of the psychological items and then the vision items, a final multidimensional scale combining both types of items was designed. The scale was administered to 124 subjects whose myopia was corrected by one of several treatment modalities to determine final construct validity. RESULTS: Using principal axis factoring and oblimin with Kaiser normalization rotation methods, five factors with strong item loadings evolved as hypothesized. The final multidimensional scale consisted of 13 items related to specific aspects of frequency of visual compromise and ocular symptoms with 13 corresponding items for level of tolerance for these problems; three items related to cosmesis; 10 items related to psychological characteristics; and six items related to personality traits. Good internal consistency in each factor (Cronbach's alpha range, 0.76 to 0.92) for the scale was evident. DISCUSSION: This report describes the development and validation of an easily administered, short, effective multidimensional health-related quality-of-life questionnaire for use in selecting and measuring success of methods for correcting myopia.

Adult↗
PubMed1998

Lacquer cracks following laser treatment of choroidal neovascularization in pathologic myopia.

BACKGROUND: Lacquer cracks are breaks in the retinal pigment epithelial-Bruch's membrane-choriocapillaris complex and are manifestations of pathologic myopia. Progressive posterior segment elongation, uveal scleral thinning, and retinal pigment epithelial degeneration are thought to create a predisposition for crack formation in these eyes. In turn, choroidal neovascularization (CNV) may develop within the cracks to produce disciform scarring of the macula. This study examined lacquer cracks as a possible consequence of laser photocoagulation of CNV. METHODS: From the files of two retinal referral practices, five patients were located in whom lacquer cracks developed or expanded after laser photocoagulation for macular CNV in pathologic myopia. The mean age of the patients was 54.8 years. Four patients were treated with krypton red laser and one with an argon laser. Laser settings were available for only one of the patients. RESULTS: After laser photocoagulation, lacquer cracks were noted to expand in one or two directions from the laser scar between 10 days and 3 months of the treatment. The cracks also served as a pathway for progressive or recurrent neovascularization. CONCLUSIONS: Although lacquer cracks occur spontaneously in pathologic myopia, expansion, elongation, or simple development of a crack may occur as a result of laser photocoagulation of CNV. The new cracks also serve as a potential risk for recurrent neovascularization. This potential adverse complication should be considered in the management of CNV in pathologic myopia with laser treatment.

Adult↗
PubMed2001

Natural history of choroidal neovascularization in high myopia.

High myopia, or pathologic myopia, usually refers to a condition in which individuals have greater than 6 diopters of myopia or an axial length greater than 26 to 27 mm. The natural history of choroidal neovascularization in high myopia is variable, and reports to date have some conflicting information, but analysis shows fairly poor final visual outcomes. This outcome complicates recommendations for treatment and must be considered in future studies aimed at managing this disease.

Choroidal Neovascularization↗
PubMed2006

Intrastromal corneal ring implantation (360 degrees ring) for myopia: a 5-year follow-up.

PURPOSE: Stability of correction is a major factor for successful refractive surgery. Intrastromal corneal rings were placed for the correction of low to moderate myopia beginning 10 years ago. The purpose of this study was to evaluate findings in patients 5 years after ring placement and to compare these findings with 1-year results to assess the stability of effect. METHODS: Seventy-two patients (113 eyes) with myopia (range, -0.75 to -4.50 diopters [D]) were treated with the placement of intrastromal corneal rings (360 degrees ), in a multicenter clinical trial between 1993 and 1994 under U.S. Food and Drug Administration phase II and phase III clinical trials. Six insert sizes were evaluated: 0.21, 0.25, 0.30, 0.35, 0.40, and 0.45 mm. The long-term results that were evaluated were uncorrected visual acuity, best spectacle-corrected visual acuity, cycloplegic refraction spherical equivalent at 5 years and proximity of this value to the target refraction determined preoperatively, induced manifest refraction cylinder, and slitlamp findings. RESULTS: Data at the 5-year follow-up showed that uncorrected visual acuity was 20/40 or better in 83% of eyes and 20/20 or better in 64% of eyes, compared to 88% and 43%, respectively, at the first year of follow-up. Only 7% of eyes lost two or more lines of preoperative best spectacle-corrected visual acuity at 5 years, compared to 11% at the first year. No eyes at the 1- or 5-year follow-up had a best spectacle-corrected visual acuity worse than 20/40. Cycloplegic refraction spherical equivalent was within 1.00 D of target refraction in 68% of eyes at 5 years, compared to 71% at the 1-year follow-up. Induced manifest refraction cylinder greater than 1.00 D was reduced to 5% of eyes in the fifth year, compared to 12% of eyes at year 1. CONCLUSIONS: Intrastromal corneal rings are a safe, effective, and stable method of correcting mild to moderate myopia, and most patients continue to be satisfied with the results after 5 years. There was no clinically significant change in refractive effect and the central corneas remained clear at the 5-year follow-up in all eyes studied. Further data are currently being collected for 10-year follow-up periods. It is hypothesized that the use of intrastromal corneal rings as a refractive option for mild to moderate myopia will be supported by these additional longitudinal data.

Corneal Stroma↗
PubMed2005

Accommodation, accommodative convergence, and response AC/A ratios before and at the onset of myopia in children.

PURPOSE: The purpose of this study was to investigate accommodation, accommodative convergence, and AC/A ratios before and at the onset of myopia in children. METHODS: Refractive error, accommodation, and phorias were measured annually over a period of 3 years in 80 6- to 18-year-old children (mean age at first visit = 11.1 years), including 26 who acquired myopia of at least -0.50 D and 54 who remained emmetropic (-0.25 to + 0.75 D). Refraction was measured by noncycloplegic distance retinoscopy. Concomitant measures of accommodation and phorias were taken for letter targets at 4.0 m and 0.33 m using the Canon R-1 open field-of-view autorefractor with an attached motorized Risley prism and Maddox rod. The accommodation and phoria measurements were used to calculate response AC/A ratios. RESULTS: Compared with children who remained emmetropic, those who became myopic had elevated response AC/A ratios at 1 and 2 years before the onset of myopia, in addition to at onset and 1 year later (t's = -2.97 to -4.04, p < 0.01 at all times). The significantly higher AC/A ratios in the children who became myopic are a result of significantly reduced accommodation. Accommodative convergence was significantly greater in myopes only at onset. CONCLUSIONS: These findings suggest that the abnormal oculomotor factors found before the onset of myopia may contribute to myopigenesis by producing hyperopic retinal defocus when a child is engaged in near-viewing tasks.

Accommodation, Ocular↗
PubMed2006

Comparison of implantable collamer lens (ICL) and laser-assisted in situ keratomileusis (LASIK) for low myopia.

PURPOSE: To compare the results of laser-assisted in situ keratomileusis (LASIK) and implantable collamer lenses (ICL) in the correction of myopia -4 to -7.88 D. METHODS: A total of 1678 LASIK eyes from the Davis Duehr Eye Center, Madison, WI, and 144 ICL eyes from the 14-site US FDA Clinical Trial for ICL for Myopia were compared. Both series were concurrently operated on with 4 to 7.88 D of preoperative spherical equivalent of the manifest refraction and were examined at 1 day, 1 week, 1 month, and 6 months postoperatively. The mean baseline myopia was slightly higher in the ICL group (ICL: -6.4 +/- 1.1 D; LASIK: -5.6 +/- 1.1 D). Best spectacle-corrected visual acuity (BSCVA), uncorrected visual acuity (UCVA), and refractions were collected prospectively in both series. RESULTS: BSCVA loss of at least 2 lines was significantly higher in the LASIK series in the early healing period (1 week: 6% vs. 0.7%; P = 0.008), whereas a BSCVA gain of at least 2 lines was statistically better with the ICL at 1 (5% vs. 0.9%, P = 0.001) and 6 months (4% vs. 0.8%, P = 0.013). Proportion of cases seeing 20/15 or better uncorrected (21.6% vs. 7.8%, P < 0.001) and 20/20 or better (67% vs. 57%, P = 0.027) at 6 months postoperatively was better in the ICL group. The ICL was statistically more predictable (attempted vs. achieved) at 6 months; +/-0.50 D (79% ICL vs. 70% LASIK, P = 0.034) and +/-1.0 D (97% ICL vs. 88% LASIK, P < 0.001). Stability was achieved (95% < or = 1.0 D) at the 1-week to 1-month interval for both groups (95% LASIK; 98% ICL). The stability of refraction (< or =0.5 D change) was significantly better in the ICL group than the LASIK group through 6 months. No serious complications occurred in either series. CONCLUSIONS: The ICL was safer and more effective than LASIK and seems to be a viable alternative to corneal refractive excimer surgery in the treatment of low myopia.

Adult↗
PubMed1995

Excimer laser surgery for myopia and myopic astigmatism.

Photorefractive keratectomy using the Summit Excimer Laser has been carried out on 1333 eyes with myopia or myopic astigmatism which have been followed up for six months or longer. Of those, 607 have been followed up for one year. Of the eyes with myopia or myopic astigmatism of up to 3 dioptres spherical equivalent, at one year 85.6% had unaided vision of 6/6, 97.2% 6/9 or better, and 99.4% 6/12 or better. Of the eyes between -3.25 and -6.00 dioptres spherical equivalent at one year 72.1% achieved 6/6 vision unaided, 88.8% 6/9 or better, and 94.2% 6/12 or better. Of the eyes between -6.25 and -10.00 dioptres, at one year 49.6% achieved 6/6 vision unaided, 76.1% 6/9 or better and 88.0% 6/12 or better. To achieve these figures, 28% of the patients had astigmatic keratotomy, either two or three weeks before photorefractive keratectomy, or at the same time as photorefractive keratectomy. Photorefractive keratectomy is as predictable as radial keratotomy in eyes of under 6 dioptres myopia, but is more predictable than radial keratotomy in higher myopia. Photorefractive keratectomy has the advantages of leaving an eye which is structurally sound, and without diurnal variation of focusing.

Adult↗
PubMed2006

Fellow eye of patients with retinal detachment associated with macular hole and bilateral high myopia.

PURPOSE: To estimate the risk of retinal detachment in the fellow eye of patients with bilateral high myopia who had retinal detachment associated with macular hole (MH-RD) in one eye. METHODS: The present study examined retrospectively 56 patients with bilateral high myopia who had MH-RD. To determine the incidence of involvement of the fellow eye, patients who completed a follow up of 12 months or longer were eligible for the current study. RESULTS: Of 56 patients with MH-RD due to high myopia, 54 had unilateral detachment at presentation and two had bilateral detachment. Of the 54 highly myopic fellow eyes without retinal detachment at presentation, 37 eyes underwent 12 or more months of documented follow up. Mean follow up after initial surgery to the primary eye was 6.5 +/- 4.9 years. During follow up, a macular hole without retinal detachment was noted in one (2.7%) of these 37 eyes. Three other eyes (8.1%) had MH-RD at 1, 2 and 7 years, respectively, after the initial surgery to the primary eye. At the final visit, 12 eyes (32%) had visual acuity of > or =6/9, whereas 12 eyes (32%) had visual acuity of < or =6/60. CONCLUSIONS: When patients with bilateral high myopia have MH-RD in one eye, they would be expected to be at increased risk of retinal detachment in the fellow eye.

Aged↗