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At least 631 records · Page 35Linked to original sources
PubMed2000

[Translocation of the macula for retrofoveal choroidal neovascularization in age-related macular degeneration and severe myopia: first results].

BACKGROUND: Subfoveal choroidal neovascularization is a main cause of blindness. The new surgical technique of macular translocation conceived by De Juan, with scleral shortening and without a retinotomy, allows to move the fovea away from the neovascular membrane with a low rate of complications. The first results obtained with this technique are presented here, in cases of submacular neovascularization due to age-related macular degeneration (AMD) or degenerative myopia. PATIENTS AND METHODS: The first 10 patients who were operated on with this technique presented with subfoveal neovascularization due to AMD (6 eyes) or myopia (4 eyes). The time period between the beginning of the disease and surgery was less than 3 months. Before and after surgery, a complete examination included fluorescein and ICG angiographies and OCT. RESULTS: Visual acuity improved by 2 lines or more in 6 eyes (60%), was unchanged in 3 eyes (30%) and decreased in 1 eye. The improvement in vision seemed higher in myopia than in ARMD. Conversely, the mean foveal displacement was greater in ARMD than in myopia (1.2 disc diameter and 0.5 respectively). Laser photocoagulation has been performed in all patients after surgery. Main complications were retinal detachment (1 eye) and neovascularization at the site of transretinal injection (1 eye). Mean follow-up was 3 months. COMMENTS: Macular translocation with the technique described by De Juan allowed visual improvement in more than the half of the eyes with subfoveal neovascularization, resulting in a moderate rate of complications. Long term follow-up is necessary to confirm these results.

Age Factors↗
PubMed2000

Decreased proteoglycan synthesis associated with form deprivation myopia in mature primate eyes.

PURPOSE: The rate of proteoglycan synthesis was measured in the scleras of adolescent marmosets that had undergone monocular form deprivation to characterize the scleral extracellular matrix changes associated with the development of myopia in a mature primate. METHODS: Form deprivation myopia was induced in adolescent marmosets by unilateral lid suture for an average of 108 days. After the lids were reopened, the axial lengths and refractions were measured at intervals for up to 39 weeks. At the end of the study period, sclera were isolated and immediately radiolabeled with 35SO4 in organ culture. Proteoglycan synthesis rates were determined by measurement of 35SO4 incorporation into cetylpyridinium chloride-precipitable glycosaminoglycans after digestion of the scleral samples with proteinase K. Collagen content was determined by measurement of total hydroxyproline in scleral digests. Newly synthesized proteoglycans were separated on a Sepharose CL-4B molecular sieve column and identified by their core proteins by Western blot analyses. RESULTS: Lid suture resulted in myopia due to a significant increase in vitreous chamber depth. After Sepharose CL-4B chromatography, newly synthesized scleral proteoglycans isolated from normal, form-deprived, and contralateral control eyes, resolved into one major peak that eluted in the position of decorin, a small chondroitin-dermatan sulfate proteoglycan. After digestion of the major peak with chondroitinase ABC, an approximately 45-kDa core protein was detected by Western blot analyses, confirming the presence of decorin. Form deprivation resulted in a significant reduction in the rate of proteoglycan synthesis in the posterior sclera (-43.55%, P < or = 0.001). Proteoglycan synthesis was also significantly reduced in the posterior sclera of form-deprived eyes relative to total collagen content (-36.19%, P < or = 0.01) and was negatively correlated with the rate of vitreous chamber elongation in the deprived eye (r2 = 0.779, P < or = 0.05). CONCLUSIONS: Significant extracellular matrix remodeling occurs in the posterior sclera of the adolescent primate eye during vitreous chamber elongation and myopia development. The negative correlation between vitreous chamber elongation rates and the synthesis rates of decorin in form-deprived eyes suggests that proteoglycan synthesis within the posterior sclera plays a role in the regulation of ocular size and refraction in the adolescent marmoset.

Animals↗
PubMed2000

[The excimer laser and severe myopia--comparison of LASIK and PRK].

The aim of this study is to compare the results of photorefractive keratectomy (PRK) with method of laser-assisted keratomileusis (LASIK) in the treatment of high myopia by excimer laser. The study compares 100 eyes after PRK operated on by technique of multizonal ablation divided into group of moderately high myopia (-6.0 ... -9.0 Dsph/85 eyes) and severely high myopia (over -9.25 Dsph/15 eyes) with a group o 100 eyes operated on by LASIK similarly classified (moderately high myopia/67 eyes and severely high myopia/33 eyes). The eyes were treated by excimer laser Keracor 117 manufactured by Technolas company. Statistic analysis used one-way analysis of variance. One year after operation emmetropia within +/- 1.0 Dsph was 52% in the first and 47% in the second group after PRK. After LASIK it was 71% and 54% respectively. No statistically significant differences have been found between the groups. In spite of this, analysis of postoperative complications, line loss of the preoperative best spectacle corrected acuity and patients satistaction shows that LASIK is a better method in correction of high myopia by excimer laser.

Adult↗
PubMed2000

[A myopia study of glaucoma patients following pilocarpine instillation].

AIM: Our research studies transitory myopia induced by Pilocarpine treatment in glaucoma patients. MATERIAL AND METHODS: 48 patients with open angle glaucoma were selected, visual acuity and refraction were measured before and after the instillation of Pilocarpine 2%, for two hours. Induced myopia was compared for different ages and it was established the influence of Timolol and Acetazolamide administered in the same time. RESULTS: Transitory myopia is important in young patients, reduced after 50 years and absent after 70 years. Acetazolamide increases myopia, Timolol has no effect on refraction. CONCLUSIONS: The study confirms the unpleasant effect of Pilocarpine and suggests not performing refractometry in the first two hours after the instillation of the drug.

Adult↗
PubMed2001

Myopia in Singapore kindergarten children.

PURPOSE: The purpose of this study was to examine whether close-up work was related to myopia in Singapore kindergarten children. METHODS: One hundred twenty-eight children, ages 3 to 7 years, from a kindergarten in Singapore were examined by cycloplegic autorefraction. The parents also completed a questionnaire on the different types of close-up work activities each child was engaged in, socioeconomic status, and parental history of myopia. RESULTS: Myopic children spent 3.0 hours per day (median) on close-up work activity, while nonmyopic children spent 2.0 hours per day (median) on close-up work activity. The prevalence of myopia in the sample was 8.6%. CONCLUSION: Close-up work activity was not related to myopia in pre-school children.

Child↗
PubMed2001

Determination of corneal asphericity after myopia surgery with the excimer laser: a mathematical model.

PURPOSE: To determine the theoretical change of corneal asphericity within the zone of laser ablation after a conventional myopia treatment, which conforms to Munnerlyn's paraxial formula and in which the initial corneal asphericity is not taken into consideration. METHODS: The preoperative corneal shape in cross section was modeled as a conic section of apical radius R(1) and shape factor p(1). A myopia treatment was simulated, and the equation of the postoperative corneal section within the optical zone was calculated by subtracting the ablation profile conforming to a general equation published by Munnerlyn et al. The apical radius of curvature r(2) of the postoperative profile was calculated analytically. The postoperative corneal shape was fitted by a conic section, with an apical radius equal to r(2) and a shape factor p(2) equal to the value that induced the lowest sum of horizontal residuals and the lowest sum of squared residuals. These calculations were repeated for a range of different dioptric treatments, initial shape factor values, and radii of curvature to determine the change of corneal asphericity within the optical zone of treatment. RESULTS: Analytical calculation of r(2) showed it to be independent of the initial preoperative shape factor p(1). The determination of p(2) was unambiguous, because the same value induced both the lowest sum of residuals and the lowest sum of the squared residuals. For corneas initially prolate (p(1) < 1), prolateness increased (p(2) < p(1) < 1), whereas for oblate corneas (p(1) > 1), oblateness increased (p(2) > p(1) > 1) within the treated zone after myopia treatment. This trend increased with the increasing magnitude of treatment and decreased with increasing initial apical radius of curvature R(1). CONCLUSIONS: After conventional myopic excimer laser treatment conforming to Munnerlyn's paraxial formula, the postoperative theoretical corneal asphericity can be accurately approximated by a best-fit conic section. For initially prolate corneas, there is a discrepancy between the clinically reported topographic trend to oblateness after excimer laser surgery for myopia and the results of these theoretical calculations.

Cornea↗
PubMed2001

[Surgical management in subfoveal choroidal neovascularization in high myopia. Analysis of results].

PURPOSE: To analyse results obtained from treatment of choroidal neovascular membranes (CNM) in patients with high myopia after vitrectomy and CNM extraction. MATERIAL AND METHOD: A prospective study including 9 eyes (9 patients) suffering from high myopia (higher than 6 diopters of myopia and/or axial length of more than 26 mm) and subfoveal CNM treated with vitrectomy and membrane extraction. Mean age was 43.11 S.D. 9.02 years of age (range: 32-58). Mean follow up time was 28.44 S.D. 7.65 months (range: 14-39 months). RESULTS: Preoperatory best corrected visual acuity (BCVA) was 0.09 S.D. 0.05 (range: 0.01-0.2). Postoperatory BCVA resulted in 0.15 S.D. 0.09 (range: 0.1-0.4). Differences did not show statistical signification (p= 0.09, Student T test). One case of membrane recurrence was observed, one case developed increased intraocular pressure and cataract requiring extraction; another presented increased intraocular pressure in the early postoperative period. CONCLUSION: Extraction of CNM in high myopia using vitrectomy does not show significant improvements in BCVA.

Adult↗
PubMed2001

Optical response to LASIK surgery for myopia from total and corneal aberration measurements.

PURPOSE: To evaluate the optical aberrations induced by LASIK refractive surgery for myopia on the anterior surface of the cornea and the entire optical system of the eye. METHODS: Total and corneal aberrations were measured in a group of 14 eyes (preoperative myopia ranging from -2.5 to -13 D) before and after LASIK surgery. Total aberrations were measured using a laser ray-tracing technique. Corneal aberrations were obtained from corneal elevation maps measured using a corneal system and custom software. Corneal and total wave aberrations were described as Zernike polynomial expansions. Root-mean-square (RMS) wavefront error was used as a global optical quality metric. RESULTS: Total and corneal aberrations (third-order and higher) showed a statistically significant increase after LASIK myopia surgery, by a factor of 1.92 (total) and 3.72 (corneal), on average. This increase was more pronounced in patients with the highest preoperative myopia. There is a good correlation (r = 0.97, P < 0.0001) between the aberrations induced in the entire optical system and those induced in the anterior corneal surface. However, the anterior corneal spherical aberration increased more than the total spherical aberration, suggesting also a change in the spherical aberration of the posterior corneal surface. Pupil centration and internal optical aberrations, which are not accounted for in corneal topography, play an important role in evaluating individual surgical outcomes. CONCLUSIONS: Because LASIK surgery induces changes in the anterior corneal surface, most changes in the total aberration pattern can be attributed to changes in the anterior corneal aberrations. However, because of individual interactions of the aberrations in the ocular components, a combination of corneal and total aberration measurements is critical to understanding individual outcomes, and by extension, to designing custom ablation algorithms. This comparison also reveals changes in the internal aberrations, consistent with the posterior corneal changes reported using scanning slit corneal topography.

Adult↗
PubMed1999

[The complications of excimer laser in-situ keratomileusis for myopia].

OBJECTIVE: To analyze the complications of excimer laser in-situ keratomileusis (LASIK) for myopia, investigate the causes and discuss the prevention of these complications. METHODS: The SCMD microkeratome and Schwind Keratom F excimer laser were used to correct myopia on 1,265 eyes in 662 cases. The eyes were divided into 3 groups: A: -10.00 D, 252 eyes. All of them were followed up for a period of 12 months. RESULTS: Intraoperative corneal disk completely detached: 6 eyes (0.5%); corneal disk incomplete sectioned: 3 eyes (0.2%); corneal epithelial disk: 2 eyes (0.2%); corneal interface minute foreign metal bodies: 11 eyes (0.9%); postoperative steroid intraocular hypertension: 21 eyes (1.7%); macular hemorrhage: 2 eyes (0.2%). At postoperative 3 months, there was refractive regression > 1.00 D in 0.0%, 3.1% and 7.9% respectively in the 3 groups; the increase in astigmatism > 1.00 D, 0.4%, 2.8% and 4.4% respectively. CONCLUSION: LASIK is a safe effective method for correcting myopia. Yet attention should be paid on the complications during and after operation. With the improvement in operative technique and better designed procedure, these complications can be decreased and the preoperative correctness in estimation of the postoperative results and the postoperative accuracy in the correction of myopia can be elevated.

Adolescent↗
PubMed1998

[An analysis on therapeutic effects of excimer laser photorefractive keratectomy for high myopia].

OBJECTIVE: To evaluate the therapeutic effects of 193-nm excimer laser photorefractive keratectomy for the correction of high myopia. METHODS: A Keracor 116 excimer laser and a tapered transition zone technique were used to treat high myopia. It was divided into two groups: the first group -6.00 - 9.75 D, 233 eyes; the second group -10.00 - 14.00 D, 55 eyes. The effect of the tapered transition zone on refraction stability was investigated in a 12-month follow-up study. RESULTS: At one year, of these eyes, 79.4% eyes attained visual acuity of 0.5 or better, 31.6% improved to 1.0 or better, 93.8% of the eyes improved or their best corrected visual acuity did not change, whereas 6.2% lost at least one line. Corneal haze was observed to be severe in one month, and diminished considerably at 6 and 12 months. At one year, no haze could be seen in 87.4%. 52.0% were within +/- 1.00 D and 80.9% in +/- 2.00 D. During one year, 14.9% were complicated with glaucoma because of using steroid drops. CONCLUSION: These data show that excimer PRK for treatment of high myopia is an effective and safe refractive surgery. For severe myopia, it is an effective surgery, but predictability is not satisfactory, and long term follow-up is necessary.

Adolescent↗
PubMed1998

[The fluorescein angiography and indocyanine green angiography of high myopia with macular hemorrhage].

OBJECTIVE: To investigate the causes and fundus changes of high myopia with macular hemorrhage. METHODS: Color photography and fundus fluorescein angiography (FFA) were performed on 35 patients (37 eyes) of high myopia with macular hemorrhages, and indocyanine green angiography (ICGA) was performed on 8 patients. RESULTS: The causes of high myopia with macular hemorrhage could be divided into two forms: (1) macular hemorrhage with subretinal neovascularization (23 eyes), (2) macular hemorrhage without subretinal neovascularization (14 eyes). ICGA noted the neovascularization more well-defined and slightly bigger than FFA. In 9 of 14 eyes, lacquer cracks appeared at the sites of macular hemorrhage or around the hemorrhage. 6 eyes were followed up, the follow-up period ranging from 3 to 20 months (mean, 8.6 months). ICGA was performed on two patients. The results show that the rupture of choriocapillaries and Bruch's membrane can result in hemorrhage without subretinal neovascularization, and ICGA is more sensitive in detecting the lacquer cracks than FFA. CONCLUSION: Subretinal neovascularization and the formation of lacquer cracks result in two forms of high myopia with macular hemorrhage. ICGA combined with FFA is more useful in evaluating the two forms of hemorrhage.

Adolescent↗
PubMed2002

Retinal dopamine transporter in experimental myopia.

OBJECTIVE: To investigate the distribution, changes and a possible role for retinal dopamine transporter (DAT) in experimental myopia in chickens. METHODS: Two-day-old chickens were divided into four groups. Chicken eyes were fitted with lenses of -10D,-20D and translucent goggles unilaterally. Normal eyes were used as controls. After 3 wk, all chickens were given an intramuscular injection of (125)I-beta-CIT 2beta-carbomethoxy-3beta-(4-iodophenyl)tropane and sacrificed two hours post injection. Retinal pigment epithelium (RPE) and the neural retina were obtained together or RPE was dissected out from the neural retina. Radioactive DAT from each specimen was assayed by gamma-counter. RESULTS: Retinal DAT was detected in RPE specimens rather than in the neural retina in all eyes. Radioactive DAT in myopic eyes was higher, compared with control eyes. CONCLUSIONS: Retinal DAT is mainly located in the RPE and may be involved in the formation of lens induced myopia (LIM) and form deprivation myopia (FDM). These methods may provide a new approach for further studying the role of the dopamine system in experimental myopia.

Animals↗
PubMed2002

Excessive myopia and anisometropia associated with familial exudative vitreoretinopathy.

BACKGROUND: To describe associations between familial exudative vitreoretinopathy (FEVR) and refractive status. METHODS: We conducted retrospective studies of patients with clinical diagnoses of familial exudative vitreoretinopathy from June 1986 through September 2000. All patients had cycloplegic refraction, visual acuity with correction, and underwent fundus examination. Ocular history since early childhood was described. RESULTS: Nine patients were recruited. All had excessive myopia, which was noted since early childhood. Amblyopia was noted in seven of the nine patients. Asymmetric FEVR was found in four of the nine patients. In all four patients with asymmetric FEVR, anisometropia equal to or greater than 2.5D was noted. Myopia was higher and amblyopia was more severe in the eye more severely affected with FEVR. CONCLUSION: Excessive myopia, anisometropia and amblyopia were more likely to occur in eyes with familial exudative vitreoretinopathy. Patients with asymmetric disease tended to have higher myopia in the eye with more severe degree of FEVR as compared with the paired eye and thus correlated with anisometropia.

Adolescent↗
PubMed2002

The Hong Kong progressive lens myopia control study: study design and main findings.

PURPOSE: To determine whether the use of progressive addition spectacle lenses reduced the progression of myopia, over a 2-year period, in Hong Kong children between the ages of 7 and 10.5 years. METHODS: A clinical trial was carried out to compare the progression in myopia in a treatment group of 138 (121 retained) subjects wearing progressive lenses (PAL; add +1.50 D) and in a control group of 160 (133 retained) subjects wearing single vision lenses (SV). The research design was masked with random allocation to groups. Primary measurements outcomes were spherical equivalent refractive error and axial length (both measured using a cycloplegic agent). RESULTS: There were no statistically significant differences between the PAL and the SV groups for of any of the baseline outcome measures. After 2 years there had been statistically significant increases in myopia and axial length in both groups; however, there was no difference in the increases that occurred between the two groups. CONCLUSIONS: The research design used resulted in matched treatment and control groups. There was no evidence that progression of myopia was retarded by wearing progressive addition lenses, either in terms of refractive error or axial length.

Child↗
PubMedDate not supplied

[Hyperplastic connective tissue syndrome in patients with high myopia].

A conventional ophthalmologic and special somatic examination was carried out in 50 patients with myopia and 30 patients of the control group to determine hypermobility of joints by 9-point scale. Hypermobility of joints in patients with myopia was estimated at 5.95 points and in patients in the control group--2.7 points. All the patients with high myopia showed 12 various additional features of connective tissue hyperelasticity, on the average, with no more than 4 such features in the control group. It is suggested that hereditary predisposition to hyperelasticity of connective tissue determines a particular inclination of the sclera to overextension. This plays a definite role in appearance and progress of axial myopia.

Adolescent↗
PubMed2001

[Analysis on three-year follow-up results of excimer laser photorefractive keratectomy in treatment for myopia and myopic astigmatism].

OBJECTIVE: To evaluate the efficacy of excimer laser photorefractive keratectomy(PRK) on myopia and myopia astigmatism. METHODS: PRK was performed with VISXC20/20 on 377 eyes of 209 patients. Treated eyes were divided into two groups, according to their conditions before operation: Group I included 238 eyes (-1.50 to -6.00 D); Group II, 139 eyes (-6.25 to -16.00 D). All patients were followed-up for more than three years. RESULTS: Percentages of uncorrected visual acuity (UCVA) > or = 10/20 and 20/20 were 99.6% and 85.3% in Group I, and 79.9% and 48.2% in Group II respectively. Percentage of diopter < +/- 1.00 in Group I was 94.5%, and 61.9% in Group II. The rate of corneal haze of grade 0 was 100% in Group I, and 98.6% in Group II, but corneal haze of grade 2 was found in 1.2% of eyes in Group II. The postoperative intraocular pressure (IOP) of all operated eyes was normal. CONCLUSION: The results suggest that excimer laser PRK is an effective method for treating myopia and myopic astigmatism, especially for low and moderate myopia.

Adolescent↗
PubMed2003

[Studies of retinal dopamine transporter in experimental myopia].

OBJECTIVE: To investigate the distribution of dopamine transporter (DAT) in the chicken eye and to explore the role of DAT in the occurrence of experimental myopia. METHODS: Thirty 2-day-old chickens were divided into four groups. Chicken eyes were fitted with lenses of -10 D (Group 1), -20 D (Group 2) and translucent goggles (Group 3) unilaterally. Chickens without any treatments were used as the control (Group 4). The refraction and the axial eye length of all chickens were measured after 3 weeks, then, all chickens were given an intramuscular injection of (125)I-beta-CIT [2beta-carbomethoxy-3beta-(4-iodophenyl) tropane] and sacrificed two hours after injection. Retinal pigment epithelium (RPE) and neural retina were dissected from the eye as a whole layer in Groups 1 and 4; and dissected separately in Groups 2 and 3. Radioactive DAT from each specimen was assayed by gamma-counter. RESULTS: In Groups 2 and 3, the radioactive DAT value in the RPE from the experimental eyes was significantly greater than that in the neural retina and also greater than those in the RPE from the control eyes (P < 0.01). In Groups 1, 2, and 3, the radioactive DAT value in the whole retina or RPE from the experimental eyes was significantly greater than those from the control eyes (P < 0.01). CONCLUSIONS: Retinal DAT is located mainly in the RPE and may be involved in the occurrence of both lens-induced myopia and form-deprivation myopia. These methods may provide a new approach for further studying the role of dopamine system in the occurrence of experimental myopia.

Animals↗
PubMed2003

[Effects of pirenzepine on lens-induced myopia in the guinea-pig].

OBJECTIVE: To determine the efficacy of the M(1)-selective muscarinic antagonist, pirenzepine, in preventing lens-induced myopia in the guinea-pig and to study the mechanism and the possibility of treatment of myopia with pirenzepine. METHODS: Fifteen 4-week-old guinea-pigs were monocularly fitted with -10.00 D lenses for a period of 11 days. In Group I (n = 7), both eyes received topical administration of 0.24% saline vehicle as the controls. In Group II (n = 8), the lens-fitted eyes were topically treated with 10% pirenzepine, while the other eyes received the vehicle control. Ocular refraction and biometric measurements were collected on the first and the 11th days. All eyes were finally enucleated for histopathological examination to evaluate the possible toxic effects of pirenzepine. RESULTS: In Group I, 11 days of lens-fitting produced -2.45 D myopia (t = 3.141, P < 0.05) with 0.05 mm elongation of axial dimension (t = 2.500, P < 0.05) as compared to the contralateral eyes. There were no significantly differences of refractive error and axial dimensions between the experimental eyes and the controls in Group II. Histological examinations revealed no obviously toxic effects in the pirenzepine-treated eyes. CONCLUSIONS: Topical administration of the M(1)-selective muscarinic antagonist, pirenzepine, prevents lens-induced experimental myopia in guinea-pig by inhibiting the elongation of axial dimension with no obvious damage to the ocular tissues.

Animals↗