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 451 records · Page 25Linked to original sources
PubMedDate not supplied

Iris claw phakic intraocular lens for high myopia.

BACKGROUND: The implantation of a Worst-Fechner iris claw intraocular lens (IOL) is one of the surgical procedures used for the correction of high myopia. This technique reduces myopia with stable refractive results; however, its potential long-term risks have not been evaluated. We report results in 94 eyes with a minimum follow-up of 3 years. METHODS: We studied 94 eyes of 62 patients with myopia > or = -7.00 diopters (D) who underwent Worst-Fechner IOL implantation. Lens decentration, permeability of the blood-aqueous barrier by iris angiography, and changes in corneal endothelial density were analyzed. RESULTS: Mean follow-up time was 48.9 months (range 36 to 72 mo). Three years after surgery, 58 eyes (61%) had an uncorrected visual acuity > or = 20/40, and 77 eyes (82%) gained two or more lines of spectacle-corrected visual acuity with respect to the preoperative value; 75 eyes (79%) were within +/- 1.00 D of emmetropia and 46 eyes (48%) were within +/- 0.50 D of emmetropia. The mean endothelial cell loss was 17.9% at 5 years after surgery, while the percentage of hexagonality and the coefficient of cell variation tended toward preoperative levels. No vision threatening complications were seen. CONCLUSIONS: The implantation of a Worst-Fechner iris claw phakic IOL reduced high myopia with a stable refractive outcome. Endothelial cell damage was within acceptable limits. The absence of major complications makes this procedure an acceptable method for correcting high myopia.

Adult↗
PubMed1998

Retreatment of regression after photorefractive keratectomy for myopia.

PURPOSE: To study results of retreatment after regression in myopic patients who underwent photorefractive keratectomy (PRK). METHODS: Procedures were performed with the Nidek EC-5000 excimer laser. This was a retrospective study of 20 of 2127 patients, with follow-up of at least 6 months, who underwent repeated excimer laser ablation. RESULTS: No patient with low myopia had regression. We evaluated six eyes (group I) with moderate myopia; 13 eyes (group II) with high myopia; and ten eyes (group III) with extreme myopia. Average uncorrected visual acuity at 6 months after retreatment was 0.73 +/- 0.21 in group I, 0.64 +/- 0.35 in group II, and 0.61 +/- 0.38 in group III. At six months after retreatment, the average was -0.36 +/- 1.05 D in group I, -0.42 +/- 1.12 D in group II, and -1.40 +/- 1.62 D in group III. CONCLUSION: The amount and frequency of regression was higher in patients with high and extreme myopia; however, the preliminary results of retreatment of regression were satisfactory.

Adult↗
PubMedDate not supplied

Eight-year follow-up of photorefractive keratectomy for myopia.

PURPOSE: We evaluated 8-year results of excimer laser photorefractive keratectomy (PRK) for myopia in terms of stability and late complications. METHODS: Ninety-two myopic eyes of 55 patients were treated with a single-step method using an Aesculap-Meditec MEL 60 excimer laser with a 5.0-mm ablation zone. Treated eyes were divided into three groups according to preoperative refraction: low myopes (< or = -6.00 D), medium myopes (-6.10 to -10.00 D), and high myopes (>-10.00 D). RESULTS: Change in myopic regression stabilized in all myopia groups within 12 months, although a small myopic shift occurred up to 8 years after PRK. Mean change in refraction between 2 and 8 years was -0.42 +/- 0.48 D for low myopes, -0.37 +/- 0.34 D for medium myopes, and -0.41 +/- 0.50 D for high myopes. The percentage of eyes within +/- 1.00 D of emmetropia 8 years after PRK was 78.3% in the low myopia group, 68.8% in the medium myopia group, and 57.1% in the high myopia group. One eye lost 2 lines of best spectacle-corrected visual acuity due to irregular astigmatism. In 13.0% of eyes, a residual trace corneal haze was observed, which had no effect on visual acuity. Apart from the loss of 2 lines of BSCVA in one eye, there were no other late complications during the study period. CONCLUSIONS: The mean change in refraction between 2 and 8 years was less than -0.50 D, regardless of preoperative refraction, and may be attributed to natural age-related refractive change. The appearance of residual corneal haze after 8 years correlated with the amount of myopic correction. PRK was a safe and stable surgical procedure in this group of patients.

Adult↗
PubMedDate not supplied

Wavefront aberration outcomes of LASIK for high myopia and high hyperopia.

PURPOSE: To determine the higher order aberrations at the corneal first surface after conventional LASIK for high myopia and high hyperopia. METHODS: This was a retrospective study using a convenience sample with subjects divided into five groups by level of refractive correction. Group 1 were normals, having no eye disease or previous surgery, but may have had refractive error. Group 2 had low myopia (-1.00 to -5.87 D), group 3 high myopia (> 6.00 D), group 4 low hyperopia (+1.00 to +3.87 D), and group 5 high hyperopia (> 4.00 D). LASIK was performed using a Technolas 217 laser. Corneal topography was taken with Orbscan II, and Placido data exported to VOLPro software v6.71. Wavefront aberrations were determined for a 6.0-mm pupil. RESULTS: The study included 264 subjects-group 1 (normal), n=204; group 2 (low myopia), n=20; group 3 (high myopia), n=20; group 4 (low hyperopia), n=10; and group 5 (high hyperopia), n=10. The spherical equivalent refractive error corrected (mean +/-SD) was 0.00 +/- 0.00 D in group 1, -3.92 +/- 1.47 D in group 2, -9.53 +/- 2.06 D in group 3, +2.49 +/- 0.51 D in group 4, and +5.54 +/- 1.22 D in group 5. The total higher order root-mean-square (RMS) wavefront aberration was 0.38 +/- 0.07 microm in group 1, 0.69 +/- 0.22 microm in group 2, 1.36 +/- 1.79 microm in group 3, 0.64 +/- 0.34 microm in group 4, and 1.76 +/- 0.54 microm in group 5. Spherical aberration was 0.25 +/- 0.06 mcirom in group 1, 0.45 +/- 0.11 microm in group 2, 0.64 +/- 0.29 microm in group 3, -0.11 +/- 0.15 microm in group 4, and -0.56 +/- 0.22 microm in group 5. The refractive correction (Rx) was highly correlated to total higher order RMS for myopic correction higher order RMS = 0.38 - 0.07 Rx, R2=0.52, and for hyperopic correction higher order RMS = 0.18 + 0.28 Rx, R2 = 0.75. CONCLUSIONS: Conventional LASIK increases all corneal higher order aberrations with induced aberrations increasing with the magnitude of refractive correction. High refractive corrections, both myopic (>6.00 D) and hyperopic (>5.00 D), can lead to very high levels of corneal higher order aberrations.

Astigmatism↗
PubMedDate not supplied

[Comparative results evaluation of residual myopia and astigmatism correction after radial keratotomy by photorefraction keratectomy and laser specialized keratomileusis].

The results of correction of residual myopia by photorefraction keratectomy (PRK) (51 eyes) and laser specialized keratomileusis (LASIK) (36 eyes) after radial keratotomy (RK) are compared. The patients were observed for up to 12 months. After PRK, 7.3% patients developed late fleur of the cornea, evaluated by at least 2 points. The incidence of fleur directly depended on the value of residual myopia. After LASIK none of the patients developed such fleur. The best visual acuity (0.5 and higher without correction) was attained in 70.73% after PRK and RK, vs. 100% after LASIK. The results of photorefraction operations and severity of residual myopia after RK correlated. In residual myopia of up to -3 diopters the results of correction by PRK and LASIK were virtually the same. In residual myopia higher than -3 diopters, LASIK is preferable.

Adult↗
PubMed1999

Prevention of form-deprivation myopia with pirenzepine: a study of drug delivery and distribution.

The present study investigated the drug distribution and elimination profiles in ocular tissues of pirenzepine, a selective M1 muscarinic antagonist known to inhibit myopia. Results demonstrate that (1) Intravitreal injections of the M1 selective antagonist pirenzepine were more effective at preventing form-deprivation myopia than subconjunctival injections. (2) Maximum drug levels were reached within 1 hr for both retina and sclera following intravitreal (28 and 11 nanomole) and subconjunctival (0.25 and 1 nanomole) injection. Intravitreal injection proved a more effective route of drug delivery to all ocular tissues compared to subconjunctival injection. (3) Elimination times of pirenzepine from ocular tissues were much shorter than those reported for blood plasma. (4) Histological examination revealed no evidence of gross toxic effects at doses effective in inhibiting induced axial myopia. In conclusion, pirenzepine was effective at reducing form-deprivation myopia in a dose-dependent manner with no evidence of disruption to the retina. However, results were not conclusive as to where pirenzepine may have its site of action in preventing form-deprivation myopia.

Animals↗
PubMed2000

Induced myopia associated with increased scleral creep in chick and tree shrew eyes.

PURPOSE: To investigate the role of scleral creep in the axial elongation of chick and tree shrew eyes with induced myopia. METHODS: Form-deprivation myopia was induced with a diffusing occluder worn over one eye. Scleral samples from the posterior pole and equatorial regions of myopic, contralateral (control), and age-matched normal chick and tree shrew eyes were loaded in vitro with a force of 5 g for 20 minutes while creep extension was monitored. The elastic behavior of sclera from myopic, control, and normal chick eyes was also compared. RESULTS: In both chick and tree shrew, posterior and equatorial scleral samples from myopic eyes had significantly (P < 0.05) greater creep extensions than equivalent samples from control and normal eyes (n = 10, each group). Among individual tree shrews the difference in creep rate between the sample from the myopic eye and that from the control eye correlated with vitreous chamber elongation (r = 0.746, P < 0.05) and development of myopia (r = 0.792, P < 0.01) in the deprived eye. No such association was found in the data from chicks. The elastic properties of chick sclera were unaffected in form-deprivation myopia. CONCLUSIONS: In chick and tree shrew, form-deprivation myopia is associated with increased creep rate of posterior and equatorial sclera. In tree shrew, the correlation between increased scleral creep rate and vitreous chamber elongation in myopic eyes supports the hypothesis that induced changes in the axial length of the mammalian eye are mediated by changes in the creep properties of the sclera.

Animals↗
PubMed2000

Management of progressive school myopia with topical atropine eyedrops and photochromic bifocal spectacles.

PURPOSE: To report our results of medical management of myopia, and add these to the prior literature supporting this practice. METHOD: Retrospective review of the medical records of 35 patient-subjects offered this treatment with adequate followup over a five year period. Treatment consisted of prescription of photochromic gray extra lenses incorporating full myopic correction with a +3.00 bifocal addition, and atropine 1% ophthalmic drops, one in each eye, each night at bedtime. Compliance was monitored based upon mydriasis and cycloplegia. RESULTS: The mean change in refractive error per year was +0.07 diopters for the always compliant group, that is, a decrease in the amount of myopia; -0.18 diopters per year for the sometimes compliant group; and -0.17 diopters for the never compliant group, an increase in the degree of myopia. Statistical comparison of our always compliant group with each of the other two groups using the t-test, yielded a P value of P<.10 in each case, considered to be "medically/clinically significant". Comparison of the mean annual change in refractive error of our always compliant group (+0.07 D/yr) with the mean annual change in re-fractive error in the general population aged 8-15 years (-0.24 D/yr) shows an absolute difference of 0.31 D/yr. This difference is "statistically significant" (t-test) with a P <.02. CONCLUSION: Atropine and bifocals are an appropriate, effective, and safe management for progressive school myopia; and probably also for pathological myopia.

Adolescent↗
PubMed2001

Effects of nicotinic antagonists on ocular growth and experimental myopia.

PURPOSE: To learn whether nicotinic cholinergic receptors modulate postnatal eye growth and influence the course of form-deprivation myopia. METHODS: One-week-old White Leghorn chicks wore a unilateral goggle to induce form-deprivation myopia. Other chicks were never goggled. Nicotinic antagonist drugs were administered by intravitreal injection, usually daily or every other day to the goggled eye or to one eye of never-goggled chicks. After 1 week, the eyes were studied by refractometry, A-scan ultrasonography, and caliper measurements. RESULTS: The relatively non-subtype-specific channel-blocking nicotinic antagonists chlorisondamine and mecamylamine each inhibited the development of form-deprivation myopia but with complex multiphasic dose responses. Chlorisondamine was the most effective. Mecamylamine, at the lowest tested doses, tended to stimulate the growth response and myopic refractive shift of goggle wearing. Methyllycaconitine competitively inhibits nicotinic receptors containing the alpha7 and alpha8 subunits, which are highly expressed in chick retina. It showed a less dramatic but still significant inhibitory effect on myopia. The effects of dihydro-beta-erythroidine, a competitive antagonist relatively selective for nicotinic receptors with alpha3 or alpha4 subunits and particularly for alpha3beta2-containing receptors, were the weakest and inhibited primarily axial elongation. Chlorisondamine but not mecamylamine also affected nongoggled eyes, inhibiting growth and shifting refraction toward hyperopia, but chlorisondamine also induced degenerative changes to the retinal pigment epithelium (RPE). CONCLUSIONS: Nicotinic receptors are involved in eye growth control. Nicotinic antagonists affect the development of form-deprivation myopia and perhaps the growth of nongoggled eyes. The differences in drug activity and multiphasic dose-response curves may reflect the complexity of nicotinic receptor subtypes associated with the eye and/or pharmacokinetic differences between the individual drugs. Although another tissue(s) cannot be completely excluded by these data, the site of action of these agents may be neural retina or RPE.

Animals↗
PubMed2000

[Analysis of influence of axial length and keratometric value on the curative effects of excimer laser photorefractive keratectomy for myopia].

OBJECTIVE: To evaluate the influence of axial length (AL) and keratometric value (KV) on the curative effects of excimer laser photorefractive keratectomy (PRK) for myopia. METHOD: A Keracor-17 excimer laser was used to treat 80 patients (121 eyes) with myopia. The cases were divided into three groups according to the AL and KV: The first group AL > 26 mm, KV 45 D, 36 eyes; the third group AL 0.05). The cases with uncorrected visual acuity >or= 0.5 had significant difference between the first and the second group and between the first and the third group (chi(2) = 6.30, P < 0.05). Multiple linear regression and correlative analysis showed that the increase in ocular axis was an unfavorable factor to visual acuity, while the increase in keratometric value was a favorable factor to visual acuity. CONCLUSION: PRK for treatment of myopia is an effective and safe refractive surgery. When the myopic degrees are identical, the postoperative outcome of myopia with increase in keratometric value as the main pathogeny is better than the myopia with increase in axial length as the main pathogeny.

Adolescent↗
PubMed2002

Volume estimation of excimer laser tissue ablation for correction of spherical myopia and hyperopia.

PURPOSE: To determine the theoretical volumes of ablation for the laser treatment of spherical refractive errors in myopia and hyperopia. METHODS: The cornea was modeled as a spherical shell. The ablation profiles for myopia and hyperopia were based on an established paraxial formula. The theoretical volumes of the ablated corneal lenticules for the correction of myopia and hyperopia were calculated by two methods: (1) mathematical approximation based on a simplified geometric model and (2) finite integration. These results were then compared for optical zone diameters of 0.5 to 11.00 mm and for initial radii of curvature of 7.5, 7.8, and 8.1 mm. RESULTS: Referring to a simplified geometrical model, the volume of ablated corneal tissue was estimated to be proportional to the magnitude of treatment (D) and to the fourth power of the treatment diameter (S(4)). For refractive correction of myopia and hyperopia, volume estimations using our formula, V congruent with D. (S/9)(4), were similar to those obtained by finite integration for optical zone diameters of 0.5 to 8.5 mm and for corneal radii of curvature within the clinical range (7.5, 7.8, and 8.1 mm). CONCLUSIONS: The theoretical volume of corneal tissue ablated within the optical zone for spherical corrections can be accurately approximated by this simplified formula. This may be helpful in evaluating factors that contribute to corneal ectasia after LASIK for myopia and hyperopia. Treatment diameter (S) is the most important determinant of the volume of tissue ablation during excimer laser surgery.

Cell Size↗
PubMed2002

A retrospective study of myopia progression in adult contact lens wearers.

PURPOSE: To study retrospectively the frequency of myopia progression and risk factors for progression in a sample of adult contact lens wearers. METHODS: From a database of 815 soft contact lens wearers, patients were identified whose age was between 20 and 40 years, who had at least -0.50 D spherical equivalent of myopia in both eyes, three or more refractions, and > or =5 years of follow-up. Only data from the right eye were used. Progression was defined as an increase of at least -1.00 D over 5 years. Subjects were also asked to complete a questionnaire regarding their ocular history, demographics, family history, and the amount of time spent performing different tasks at home and at work. RESULTS: Two hundred ninety-one subjects met the eligibility criteria with a mean baseline refractive error of -3.29 +/- 1.92 D and a mean age of 28.5 +/- 5.0 years. Of these, 21.3% progressed by at least -1.00 D over the 5-year period. The 5-year rate of progression decreased with increasing age (chi(2) = 12.44, P = 0.006). One hundred ninety-seven subjects (67.6%) completed and returned questionnaires. "Progressors" (N = 41) did not differ from "nonprogressors" (N = 156) in terms of hours per day spent reading and writing, computer use, education level, family history of myopia, age of onset of myopia, and contact lens wear. CONCLUSIONS: In this database of soft contact lens wearers, myopia progression was common for subjects in their twenties and less common for those in their thirties.

Adult↗
PubMed2002

[The quality of life in patients with pathologic myopia].

PURPOSE: To evaluate the functional status of daily life and the quality of life of pathologic myopia patients. METHODS: A cross-sectional study was conducted using data from pathologic myopia patients(n = 211) and control subjects(n = 144). The influence of the disease on the daily life and the quality of life of patients were evaluated using a self-rating questionnaire. The questionnaire covered the full range of the status of patients' daily life and the quality of life of pathologic myopia patients, including daily tasks depending on visual acuity, social and emotional handicaps, and cognition of disease. RESULTS: The functional status of daily life and the quality of life of patients was reduced compared with control subjects. The influence of pathologic myopia on the patients' daily lives was primarily the result of three major factors: handicap, disability, and support. All three correlated with the quality of life, the degree of handicap having the strongest correlation. CONCLUSION: The functional status of daily life and the quality of life of patients was reduced; this reduction in quality of life was attributed to disability and handicap caused by pathologic myopia.

Adolescent↗
PubMedDate not supplied

One-year results of excimer laser photorefractive keratectomy for myopia.

BACKGROUND: Excimer laser photorefractive keratectomy for the correction of myopia is presently under investigation in the United States by the Food and Drug Administration (FDA). The Phase II-B FDA study is being conducted on 75 normally sighted myopic eyes utilizing three currently available excimer lasers. This report presents the 1-year results on 12 myopic eyes treated with the VISX excimer laser system at the Ellis Eye Center at Cedars-Sinai Medical Center in Los Angeles under the Phase II-B FDA protocol. METHODS: Twelve eyes of 12 patients with myopia between -1.75 and -5.00 diopters underwent 193 nm argon/fluoride excimer laser photorefractive keratectomy. The epithelium was mechanically removed, and fixation was accomplished with a suction ring which provided nitrogen flow across the corneal surface. The computer controlled corneal ablations were 5.00 mm in diameter and were accomplished with an iris diaphragm closing from large to small. RESULTS: The preoperative spherical equivalent myopia was -3.50 D (SD = 1.02) and the postoperative myopia was -0.25 (SD = 0.48). Eleven of the 12 patients achieved an uncorrected visual acuity of 20/30 or better and were corrected to within +/- 0.50 D of emmetropia. All corneas demonstrated a mild reticular subepithelial haze which was barely visible at 1 year. There were no vision-threatening complications and none of the eyes experienced a loss of best corrected visual acuity. CONCLUSIONS: In this small trial, the excimer laser appears to be capable of accurately changing the refractive power of the cornea for the correction of myopia with minimal side effects. Only when larger numbers of patients undergo the procedure will we be able to determine the safety and efficacy of photorefractive keratectomy as a refractive surgical procedure.

Adult↗
PubMed2003

[Correction of high myopia with anterior chamber angle-supported phakic intraocular lenses--own results].

PURPOSE: To evaluate the early results: predictability, efficacy and safety of implanting new model of anterior chamber IOL for high myopia. MATERIAL AND METHODS: ICARE myopia lens (Corneal) was implanted in 20 eyes of 12 patients with preoperative myopia that ranged from -10 D to 23.5 D. Mean patient age was 32.3 years. The follow-up period was 6 months. The desired outcome was emmetropia. RESULTS: Eighteen eyes (85%) had a postoperative refraction at the last follow-up examination in a range +/- 1.0 D of emmetropia. The postoperative refraction remained stable during the entire follow-up period. Mean visual acuity before surgery, corrected with spectacle improved from 0.5 to 0.68 postoperatively without glasses in 3 months time. There was no loss in visual acuity after operation. We didn't encounter major complications. Mean endothelial cell density reduction was 3.2% in our 3 months study. CONCLUSIONS: Implantation of ICARE myopia lens to correct high myopia resulted in a stable and predictable refractive outcome. Further investigation is necessary to evaluate long-term stability and safety of this procedure.

Adult↗
PubMed2003

[Role of astigmatism in the creation of myopia].

PURPOSE: To determine, whether the presence of astigmatism has an influence on the creation of myopia. MATERIAL AND METHODS: A total of 167 people with myopia (117 women and 50 men) of the age between 12 and 51 were examined. The overall average age was 24. Routine ophthalmological examinations, keratometry as well as refractometry were carried out. The data was analysed using the coefficient of rang Spearman's correlation and the coefficient of linear Pearson's correlation. RESULTS: A negative correlation was found between the corneal astigmatism and myopia progress (P < 0.000001). A positive correlation was observed between total astigmatism and myopia (P < 0.000001). CONCLUSIONS: Corneal and total astigmatism predisposes the progress of myopia.

Adolescent↗
PubMed2004

[Variations of the zinc finger protein 161 gene in Chinese with or without high myopia].

To investigate the association between variations of ZFP161 gene and high myopia, A total of 204 probands with simple high myopia(< or = -6.0 dipoters) were collected while 116 normal persons from different families without high myopia or related disease were used as controls. Genomic DNA was prepared from the peripheral leucocytes. The coding sequences of ZFP161 gene in 320 subjects were analyzed by using exon-by-exon PCR-heteroduplex-SSCP analysis. Identification of the Variations by cloning and sequencing, combinated with controls and family analysis, was used to disclose the correlation between ZFP161 gene and high myopia. A mutation of ZFP161 gene was identified as an insertion of AT before the 58th nucleotide of intron 1 (IVS1 58-59)(1/204) and a variation of ZFP161 gene was identified as a heterozygous C to A of the 168th nucleotide in exon 2 (Codon56, GCC-->GCA, Ala56Ala). Ala56Ala is a non-sense mutation identified in 5 of the 204 patients and 3 of 116 controls. No evidence shows that these variations are responsible for high myopia.

Asian People↗
PubMed2005

[Efficacy and safety of laser-assisted in situ keratomileusis for myopia].

INTRODUCTION: The aim of this study was to assess the efficacy, frequency of re-operation and type and frequency of complications after laser-assisted in situ keratomileusis (LASIK) treatment for moderate to high levels of myopia. MATERIALS AND METHODS: 357 eyes from 190 patients were reviewed. The mean of the preoperative correction was -8.38 D (-1.75; -16 D) sph. (spherical), -1.00 D (0; 4.5 D) astigmatism. 15% (55 eyes) were re-treated. The mean of the correction before re-treatment was -2.78 D (+2.25; -11.00 D) sph., -0.43 D (0; -2.00 D) astigmatism. RESULTS: The three-month follow-up rate was 96% for primarily treated eyes and 99% for re-treated eyes. Where full correction was intended, 53% of the primarily treated and 93% of the re-treated eyes achieved an uncorrected visual acuity of > or =0.5. The refractive error for myopia less than -8 D was -0.80 D +/- 0.83 D and -1.37 D +/- 1.33 D for myopia -8 D and above after one treatment and -0.47 +/- 0.66 D after re-treatment. 1.2% (4) of the primarily treated and 3.9% (2) of the retreated eyes lost more than two lines in best spectacle-corrected visual acuity (BCVA). CONCLUSION: LASIK treatment for moderate to high levels of myopia leads in all cases to a reduced degree of myopia. There is a significant degree of unreliability on the accuracy of the treatment with a tendency to under correction. Postoperatively, many patients still have to use correction for distance vision. Significant loss of visual acuity occurs infrequently.

Adult↗