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PubMed1991

Idiopathic posterior subretinal neovascularization (IPSN) is related to myopia.

In 153 eyes with idiopathic posterior subretinal neovascularization (IPSN) and myopia of no greater than -6 dpt, the relative risk of this disorder was determined with regard to refraction. It was shown that the probability of developing this condition is directly proportional to the degree of myopia. By using data obtained from the literature for calculating the relative risk regarding refraction, it was demonstrated that the same is true for subretinal neovascularization in degenerative myopia greater than -7.5 dpt (Fuchs' spot). The relative risk for developing one of both disorders increases exponentially with increasing myopia.

Adolescent↗
PubMed1981

Biofeedback of accommodation to reduce functional myopia.

Functional myopia may be defined as the refractive condition of the eye due to spasm of the ciliary muscle. As a result of the ciliary muscle spasm, the crystalline lens becomes more convex, creating a myopic refractive condition. The normal increase and decrease in the refractive power of the crystalline lens is know as accommodation and is controlled by the autonomic nervous system innervation to the ciliary muscle. Previous studies have reported that voluntary control of accommodation is possible by biofeedback training (Cornsweet & Crane, 1973; Randle, 1970). The present research investigated the application of biofeedback control of accommodation to reduce functional myopia. A double-reversal, multiple-baseline design was used to conduct the experiment. The results revealed that the three adult male subjects achieved the preset criterion, a 1/2-diopter reduction from initial baseline to a subsequent baseline. Further analysis of the data revealed even greater changes between initial baseline and feedback periods. Although generalization to a nonexperimental environment was not trained, each subject showed a reduction in myopia and an increase in visual acuity. The results of the experiment clearly demonstrated that functional myopia is subject to voluntary control.

Accommodation, Ocular↗
PubMed1995

Retinal-image mediated ocular growth as a mechanism for juvenile onset myopia and for emmetropization. A literature review.

The very common ocular clinical ocular condition in children juvenile onset myopia results from axial elongation of the eye. In humans, some studies have found an association of myopia with greater levels of nearpoint activity and with differences in accommodation and convergence function. This paper reviews a variety of laboratory and clinical studies which are consistent with the hypothesis that retinal image defocus is biochemically transformed into an axial elongation expressed through increased posterior segment growth, and thus myopia. This paper also reviews theories of emmetropization, and classifies them as correlational, feedback, and combination. Evidence is presented to suggest that a combination theory, which combines both correlation of the ocular dioptric components and some feedback mechanism for growth of the eye, is the most correct. Current laboratory research suggests that quality and/or focus (defocus) of retinal imagery is involved in this feedback mechanism and that experimentally induced myopia might be enhanced, reduced or eliminated by pharmaceutical application. Direction of defocus may affect the rate of posterior segment growth, and thus the rate of ocular axial elongation.

Adolescent↗
PubMed2000

Phototherapeutic keratectomy combined with photorefractive keratectomy for treatment of myopia with corneal scars.

To evaluate the effect of phototherapeutic keratectomy combined with photorefractive keratectomy in the treatment of myopia with corneal scars, corneal epithelium was removed with laser plus scraping. Corneal scars were removed with PTK, followed by PRK for myopia. Healon was used to make corneal surface smoother during operation. 30 eyes of 24 cases of myopia with corneal scars were followed up for one year. Mean corrected vision was 0.51 and myopic degree was -6.42 D +/- 4.26 D before operation. After operation, corneal scars of 21 eyes (70.0%) were removed in operative zone. The vision of 27 operated eyes (90.0%) was equal to or better than best corrected vision. Mean postoperative visual acuity was 0.72. Corneal surface was smoother and astigmatism was reduced after the surgery. Our study showed that PTK combined with PRK is a safe and effective treatment for myopia with corneal scars.

Adolescent↗
PubMed2003

[Reading ability after photodynamic therapy (PDT) for age-related macular degeneration (AMD) and for high myopia].

BACKGROUND: A prospective uncontrolled follow-up of changes in reading ability after PDT with Verteporfin in patients with predominantly classic subfoveal choroidal neovascularization (CNV) due to AMD or high myopia was carried out. PATIENTS AND METHODS: A follow-up time of at least 6 months is documented for 48 patients with AMD and for 22 patients with high myopia. In addition to the usual clinical parameters the need for magnification was measured using standardized reading charts provided by the SZB.A need for magnification higher than 3.2-fold was defined as a severe loss in reading ability.PDT's were repeated every 3 months according to the usual guidelines. RESULTS: Before treatment, the mean reading acuity for patients with AMD was between 20/200 and 20/100. The average need for magnification was between 2.5-fold and 3.2-fold.Reading acuity, need for magnification and the percentage of patients with a need for magnification of 3.2-fold or less remained stable over a 6-12 months follow-up period. High myopic patients initially had a mean reading acuity of 20/200 and a need for magnification of 2.5-fold. After 9 months follow-up, reading acuity showed a mean improvement from 0.2 up to 0.3 ( p<0.05). There was also a trend towards improvement in the need for magnification and the percentage of patients with a need for magnification of 3.2-fold or less improved significantly from 68% to 78% ( p<0.05). CONCLUSION: Reading ability could be stabilized with PDT for predominantly classic subfoveal CNV in patients with high myopia or AMD for at least 9-12 months. The risk of developing a severe loss in reading ability (need for magnification >3.2-fold) was significantly reduced in high myopia and was stable over time in AMD.

Aged↗
PubMed1997

[Nuclear magnetic resonance tomography diagnosis of eye motility disorder in high-grade myopia for planning an eye muscle operation].

BACKGROUND: This study was conducted to elucidate the etiology of the acquired, restrictive motility disorder in patients with severe myopia by magnetic resonance imaging (MRI) and intraoperative situs and to verify existing theories about strabismus to develop appropriate methods of eye muscle surgery. METHODS: Thirty-five patients with unilateral or bilateral high-degree myopia and strabismus, i.e., axial length of the globe averaged 29.4 mm. Multiple coronal, transversal and parasagittal MRI planes were obtained using a Siemens Magnetom (SP 63) 1.5 Tesla MRI scanner (TR = 550 ms, TE = 15 ms; field of view = 21 x 21 cm; pixel matrix = 256 x 512; 3 acquisitions; slice thickness 2 mm; distance factor 0.25). In addition, in a dynamic MRI the patient had to fixate with the less restricted eye for 50 s in different gaze positions. All data were validated by measurements during strabismus surgery. Twenty normal orbits were studied in control MRI scans. RESULTS: The major MRI finding was dislocation of the lateral rectus in the anterior and midorbital region at an average of 3.4 mm into the temporocaudal quadrant in 13 cases with the typical eso- and hypotropia. This dislocation will reduce the abducting torque of the lateral rectus and create depressing and extorting torques. Two-anatomical explanations are possible: (1) increasing stretch of the lateral rectus because of temporocranial distension of the globe and inability of intermuscular membranes and pulleys to stabilize the path of the lateral rectus; (2) dehiscence of the lateral levator aponeurosis. The restrictive motility disorder was never caused by contact between the enlarged globe and the bones of the orbital apices. CONCLUSIONS: Until now, an abnormal path of recti EOMs has been known only in Duane's syndrome. Prior to strabismus surgery in patients with high-degree myopia, an orbital MRI scan may be useful. If misalignment of the lateral rectus is detected, the most important aim of eye muscle surgery is to normalize the pathological path of the lateral rectus. MRI morphometry in severe myopia may give additional information on the anatomy of the orbit and biomechanical mechanisms of strabismus. Our findings demonstrate the necessity of fixation-controlled MRI scans.

Adult↗
PubMed2005

Peculiar arcuate scotoma in pathologic myopia--optical coherence tomography to detect peripapillary neural tissue loss over the disc crescent.

BACKGROUND: Optical coherence tomography (OCT) was used to detect peripapillary neural tissue loss (PPNTL) over the disc crescent in pathologic myopia. The retinal neural tissue loss located inside the disc crescent in pathologic myopia is a newly recognized fundus lesion. METHODS: Review of ten eyes of ten patients with peripapillary yellowish-white retinal lesions who underwent OCT for evaluation of the nature of PPNTL in pathologic myopia. OCT, fluorescein angiography, automated visual fields, axial length measurement with ultrasound A scan, and ultrasound B scan were performed. RESULTS: Ten eyes of ten patients were identified during a 14-year period to have findings characteristic of PPNTL. The mean age of the patients was 46 years. They were followed up for an average of 9 years. The mean spherical equivalent correction was -10.50 diopters (D) (range -6.0--16.0 D). The mean axial length was 28.6 mm (range 26.30-31.50 mm). In each case, OCT showed a complete retinal discontinuity in the PPNTL lesion. Automated visual field examination showed corresponding arcuate scotoma. During the follow-up period, the inner retina layer of the retinal defect margin was elevated by posterior hyaloid and partial retinal detachment developed in one eye. CONCLUSIONS: PPNTL in pathologic myopia is a relatively asymptomatic, yellowish-white peripapillary retinal discontinuity. Recognition of this lesion is important because the visual field defect may mimic glaucomatous changes owing to the loss of nerve fiber layer. Progressive partial retinal detachment may ensue as one of the complications of the peripapillary lesion.

Adult↗
PubMed2006

Correction of high myopia with different phakic anterior chamber intraocular lenses: ICARE angle-supported lens and Verisyse iris-claw lens.

PURPOSE: To evaluate the efficacy, predictability and safety of implanting two models of anterior chamber IOLs for high myopia. Comparison of the refractive results between two groups of patients implanted with different IOLs. MATERIALS AND METHODS: Forty eyes were implanted with phakic IOLs. The ICARE myopia lens was implanted in 20 eyes of 12 patients with preoperative myopia that ranged from -21.875 to -10.0. The mean patients' age was 30 years. The Verisyse IOL was implanted in 20 eyes of 12 patients with spherical equivalent of the refractive error from -21.625 to -10.375D, and the mean patients' age was 32.25 years. The dioptric power of the intraocular lens was calculated by considering refraction, keratometry, and anterior chamber depth. The follow-up period was 12 months. RESULTS: Twelve months after surgery, the mean refractive error (SE) was -0.19D (100% of eyes were within +/-1.0D of the target refraction) in the ICARE group, and -0.86D (95% of eyes were within +/-1.0D of the target refraction) in the Verisyse group. The postoperative refraction remained stable during the entire follow-up period. The mean uncorrected visual acuity was 0.7 in the ICARE group, and 0.69 in the Verisyse group 1 year postoperatively. There was no loss in visual acuity 1 year after surgery in the ICARE implanted eyes, one patient in the Verisyse group lost 1 line of BCVA as compared to the preoperative state. Mean endothelial cell density loss was 6.12% and 6.79% in the ICARE and Verisyse groups, respectively. There were no statistically significant differences regarding the analyzed outcome parameters between the two study groups. CONCLUSION: The implantation of both anterior chamber phakic intraocular lenses to correct high myopia resulted in a stable and predictable refractive outcome. Efficacy and safety of surgery for both implanted lens models are very high.

Adult↗
PubMedDate not supplied

Prevalence of myopia in an adult population of two different ethnic groups in the Ecuadorian Amazon.

PURPOSE: To determine the prevalence of myopia in the adult populations of two different ethnic communities in the Ecuadorian Amazon. METHODS: Refraction with retinoscopy after cycloplegia was performed for 507 Naporuna (an ethnic group indigenous to the jungles of the Ecuadorian Amazon) and for 776 settlers (white-mestizos from the Andes, now living in the Amazon and working for the petroleum industry). Ages ranged from 18 to 45 years. All subjects had little or no formal education. RESULTS: The prevalence of myopia was 4.7% among the Naporuna and 5.5% among the settlers; the prevalence of hyperopia was higher, at 17.8% and 36.0%, respectively. CONCLUSIONS: The prevalence of myopia in the two communities studied agrees with the results of other studies showing a low prevalence of myopia among groups with low levels of formal education or groups living a nonurban lifestyle.

Adolescent↗
PubMed1993

Ocular development and visual deprivation myopia in the common marmoset (Callithrix jacchus).

The normal postnatal ocular development of the common marmoset (Callithrix jacchus) and the effects of visual deprivation on eye growth and refractive state are described. The marmoset normally undergoes a developmental process of emmetropization from high hyperopia at birth. This emmetropization is easily disrupted by visual deprivation produced by lid-suture. Myopia and axial elongation of the vitreous chamber are induced by visual deprivations of 12, 5, and 3 weeks duration. The development of axial myopia after 3 weeks of visual deprivation differs from longer duration deprivations in that the experimental eyes are initially shorter than normal and hyperopic at the end of the visual deprivation period, but subsequently become longer than normal and myopic. Visual deprivation myopia in the marmoset persists even after the deprivation is discontinued and a visual signal is restored. In all experimental groups, the development of the eye in response to the cessation of visual deprivation shows no slowing of vitreous chamber enlargement; the axial enlargement relative to the control eye is either maintained or increases and produces significantly greater myopia. These results suggest that the visual control of postnatal eye growth in the marmoset may be unidirectional in its response to visual experience and able only to increase the growth rate of the vitreous chamber, possibly after an initial delay.

Animals↗
PubMed1995

The effects of blockade of retinal cell action potentials on ocular growth, emmetropization and form deprivation myopia in young chicks.

To investigate the influence of brain mediated functions on control of ocular growth, young chicks were treated monocularly with intravitreally injected tetrodotoxin (TTX) to block retinal ganglion cell action potentials. TTX injections (0.7 micrograms in 7 microliters) were given on day 6 after hatching in both binocularly open and monocularly deprived chicks. Injections were repeated every 48 hr for a period of 8 days (TTX-open; TTX-MD). Control groups of animals received intravitreally injected phosphate buffered saline (PBS-open; PBS-MD) to one eye on the same schedule. There was a minimum of eight animals in each group. Recovery from form-deprivation myopia during blockade of retinal cell action potentials was also investigated. Results demonstrate that blockade of retinal cell action potentials by TTX produces reduced growth of the anterior segment of the eye and crystalline lens in both binocularly open and MD chicks. Blockade of retinal cell action potentials does not prevent form-deprivation induced vitreous chamber elongation and myopia. Form deprived myopic eyes were found to emmetropize despite blockade of retinal ganglion cell action potentials giving further evidence for local ocular control of emmetropization. Blockade of retinal ganglion cell action potentials did not prevent changes in choroidal thickness in eyes developing axial myopia or eyes recovering from induced myopia.

Action Potentials↗
PubMed1995

Raptors lack lower-field myopia.

The presence of lower-field myopia (described in chickens, pigeons, quail and amphibians) allows these animals to keep the ground in focus while performing other visual tasks. A relationship has also been reported between the eye height and the degree of myopia observed. All of the animals reported in the literature to date are ground-foraging species. Using infrared neutralizing video retinoscopy and static photoretinoscopy we found a lower-field myopia to be absent in the barn owl (Tyto alba), Swainson's hawk (Buteo swainsonii), Cooper's hawk (Accipiter cooperi) and American kestrel (Falco sparverius). These findings suggest that the presence or absence of a lower-field myopia is a function of the visual ecology of the animal.

Animals↗
PubMed1994

6-Hydroxy dopamine does not affect lens-induced refractive errors but suppresses deprivation myopia.

Degradation of the retinal image by translucent occluders during postnatal development induces axial myopia in chickens, tree shrews and monkeys. Local visual deprivation produces myopia even in local regions of the eye and neither accommodation nor intact connection between the eye and the brain are necessary. Therefore, it is an important question whether a similar local-retinal pathway translating visual information into growth or stretch signals to the underlying sclera is acting to emmetropize the growing eye. It is not known until now whether occluder deprivation triggers similar eye growth (or scleral stretch) mechanisms that are also responsible for visual guidance of normal refractive development. We here report that, in chickens, 6-hydroxy dopamine suppresses deprivation-induced myopia but has no effect on the magnitude of changes in axial eye elongation that are induced by spectacle lenses. The result suggests that, in chickens with normal accommodation, two pharmacologically different feedback loops may be responsible for deprivation myopia and lens-induced refractive errors.

Animals↗
PubMed2004

Prognostic factors influencing visual outcome of photodynamic therapy for subfoveal choroidal neovascularization in pathologic myopia.

PURPOSE: To examine the influence of age, lesion size, degree of myopia, and baseline visual acuity on the visual outcome of patients with pathologic myopia and choroidal neovascularization (CNV) who received photodynamic therapy (PDT) with verteporfin. DESIGN: Retrospective, noncomparative consecutive case series. METHODS: Forty-three eyes of 41 patients were treated in a two-year time span; 36 eyes of 36 patients who had received PDT for CNV due to pathologic myopia were examined for the above-mentioned factors 24 months after first treatment. All patients had been treated according to the Verteporfin in Photodynamic Therapy (VIP) study criteria. Patients were examined in two- to three-month intervals with Snellen visual acuity, biomicroscopy, and fluorescein angiography. RESULTS: Baseline visual acuity and age were both prognostic factors for visual outcome (P =.0097, P =.0055). Lesion size (greatest linear dimension) at baseline, refractive error, or the number of treatments had no influence on the outcome. CONCLUSION: Age and baseline visual acuity have an effect on visual outcome in patients receiving PDT due to CNV secondary to pathologic myopia. Younger patients and patients with higher baseline visual acuity had a better treatment outcome.

Adult↗
PubMed2005

Optic disk ovality as an index of tilt and its relationship to myopia and perimetry.

PURPOSE: To examine the association of optic disk ovality with myopic refractive error, axial length, and the visual field. DESIGN: Prospective observational case series. METHODS: The study included 150 randomly recruited male subjects with myopia. In all cases, one eye was randomly selected, and subjective refraction, slit-lamp examination, applanation tonometry, gonioscopy, A-scan ultrasonography, funduscopy, and color optic disk stereo photography were performed. Disk ovality was assessed using the ratio of minimum to maximum disk diameter (index of tilt). A ratio of < or = 0.8 was considered as significant disk tilt. Visual fields were tested using static automated threshold perimetry with two methods of optical correction: trial lenses and contact lenses. RESULTS: Of the total sample, 137 subjects completed the study. Mean age was 21.2 +/- 1.1 year, and mean spherical equivalent was -6.36 +/- 3.56 diopters. Mean ovality ratio was 0.83 +/- 0.09; 55 subjects (40.2%) had significant tilted optic disks. Greater optic disk ovality (tilt) correlated with greater myopia (P = .009) and longer axial length (P = .009); 95.6% of subjects had normal visual fields with both methods of optical correction. Using multiple linear regression analysis, greater tilt was independently related to a higher mean defect on testing with trial lenses (P < .01). CONCLUSIONS: Increased optic disk tilt was associated with higher myopia and reduced sensitivity on field testing. These factors are important in the assessment of glaucoma in patients with myopia.

Adult↗
PubMed2006

Evaluation of MMP3 and TIMP1 as candidate genes for high myopia in young Taiwanese men.

PURPOSE: We studied the relationship between high myopia and the MMP3 and TIMP1 genes. DESIGN: Case-control study. METHODS: We enrolled 150 high myopic individuals (< or = -6 diopters) and 262 controls (> or = -1.5 diopters) initially, and another 216 cases and 474 controls were enrolled for genotyping promising polymorphisms for replication. Thirteen polymorphisms were genotyped in the initial data. Logistic regression was used to test for genetic effects. Subset analyses were performed according to the education level and family history. RESULTS: There was no significant association between any polymorphism and high myopia in the initial data. Among the highly educated subjects, the 5A/6A polymorphism at the MMP3 gene suggested a potential relationship with high myopia, and it was genotyped in the follow-up samples. However, this polymorphism failed to show any significant results in the overall subjects. CONCLUSIONS: The two genes may not play a crucial role for high myopia in young Taiwanese men.

Adolescent↗
PubMed2006

Polypoidal choroidal vasculopathy in tilted disk syndrome and high myopia with staphyloma.

PURPOSE: To describe polypoidal choroidal vasculopathy as a complication of tilted disk syndrome and high myopia with staphyloma. DESIGN: Retrospective interventional case series. METHODS: This report was a multicenter evaluation of six patients (eight eyes) with tilted disk syndrome or high myopia that was complicated by posterior staphyloma. Complete ophthalmic examination that included fluorescein angiography, optical coherence tomography (OCT), and indocyanine green angiography (ICG-A) was performed in all patients. RESULTS: All patients had macular abnormalities and visual loss. Fundus examination and fluorescein angiography showed typical features of tilted disk syndrome (five patients; six eyes) or high myopia (one patient; two eyes) with staphyloma that was associated with polypoidal choroidal vasculopathy. OCT and ICG-A confirmed the presence of polypoidal dilations in the choroid. Seven eyes were treated with laser photocoagulation or verteporfin-photodynamic therapy (V-PDT), although one eye did not require treatment. Visual acuity at the final visit had improved in three eyes, deteriorated in three eyes, and remained unchanged in two eyes. CONCLUSION: Polypoidal choroidal vasculopathy is a potential cause of visual loss in tilted disk syndrome and high myopia. We postulate that choroidal abnormalities at the border of staphylomas induce blood-flow disturbances that are similar to those disturbances that are observed in chronic central serous chorioretinopathy, which is another condition that occasionally is associated with polypoidal choroidal vasculopathy. The pathogenesis remains unclear, and further study is required to better understand the formation of choroidal polypoidal dilations in these conditions.

Aged↗
PubMed2006

Refractive surgery for high bilateral myopia in children with neurobehavioral disorders: 1. Clear lens extraction and refractive lens exchange.

INTRODUCTION: A subpopulation of children with high myopia and neurobehavioral disorders is noncompliant with spectacle wear and ill-suited to correction using contact lenses. We report the results of refractive surgery in a series of these children treated using lensectomy alone (clear lens extraction), or lensectomy with simultaneous implantation of an intraocular lens (refractive lens exchange). METHODS: Clinical course and outcome data were collated prospectively in a group of 13 children (mean age 10.4 years, range 1 to 18 years) with neurobehavioral disorders exacerbated by chronic noncompliance with spectacle wear, causing profoundly low functional vision. Myopia in the 26 eyes ranged from -14.25 to -26.00 D (mean -19.1 D). Goal refraction was approximately +1 D. Correction was achieved by lensectomy alone in 10 eyes, and lensectomy with intraocular lens implantation in 16 eyes. Primary posterior capsulectomy/subtotal vitrectomy was performed during the primary procedure in 11 eyes (42%). Mean follow-up was 4.5 years (range 1.3 to 7.5 years). RESULTS: Myopia correction averaged 19.9 D. Eighty-one percent (21 eyes) were corrected to within +/-2 D of goal refraction and the remaining 19% (5 eyes) to within +/-4 D. Uncorrected acuity improved substantially (ie, an average 2 log units) in all 26 eyes, with commensurate gains in behavior and environmental visual interaction in 85% [corrected] of children (11/13) [corrected] Myopic regression averaged -0.16 D/year. Capsular regrowth and/or opacification necessitated vitrector or YAG-laser membranectomy in 13 [corrected] eyes (50%) [corrected] Focal retinal detachment (successfully repaired) occurred after eye contusion in one eye (4%) with cicatricial retinopathy of prematurity. CONCLUSIONS: Bilateral refractive lensectomy is effective for improving functional vision in neurobehaviorally impaired children who have high myopia (beyond the range of excimer laser correction: see companion publication) and difficulties wearing glasses. Posterior capsule regrowth/opacification is common, necessitating secondary membranectomy. Further study is indicated to determine the long-term safety of this procedure in similar pediatric populations.

Adolescent↗