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At least 1,063 records · Page 59Linked to original sources
PubMed2000

Simulation of Night Myopia in Pseudophakic Eyes.

Purpose: Eyes with an intraocular lens (IOL) implanted that have no accommodative ability are likely to have night myopia caused by Purkinje's shift and chromatic aberration. We evaluated the changes in retinal images caused by night myopia in various IOL-implanted eyes by simulation using model eyes.Methods: A polymethylmethacrylate (PMMA) IOL, soft acrylic IOLs, and high-refractive-index silicone IOLs were prepared, and inserted into the model eye. The image plane of the model eye was determined as the line image at which a slit light of 560 nm was best focused, which was regarded as emmetropic condition under photopic vision. A slit light of 505 nm was then directed into the model eye. Its line image on the image plane was blurred, which was regarded as myopic condition under scotopic vision. Under each condition. The modulation transfer functions (MTF) were calculated and the line images were photographed.Results: The degree of reduction of MTF and blurring of the line image under the night myopic condition was in the order of PMMA<soft acrylic<high refractive index silicone IOL.Conclusion: Eyes with a soft acrylic or high-refractive-index silicone IOL may have more intense night myopia caused by chromatic aberration.

Journal Article↗
PubMed2000

Orthokeratology in low myopia. Part 1: efficacy and predictability.

AIMS: Modern orthokeratology (ortho-k) using reverse geometry lens designs is being widely used for myopia reduction world-wide although there has been no well-controlled clinical trial of this procedure. This paper reports on the efficacy and predictability of an ortho-k procedure using the OK-74 lens design (now known as OK-704). METHODS: We carried out a 100-day, controlled, randomised clinical trial in which 14 subjects underwent ortho-k and a further 14 were fitted with aligned rigid contact lenses. RESULTS: The mean reduction in myopia was 1.50 (SD 0.45) D in the ortho-k group and 0.01 (SD 0.20) D in the control group. Unaided vision improved by -0.64 (SD 0.22) logMAR units in the ortho-k group, compared with -0.09 (SD 0.11) units in the control group. Variables which correlated with refractive change were corneal thickness, p-value of the nasal semi-meridian and the difference between central and peripheral corneal powers. A multiple factors model can account for 72% of the refractive change. CONCLUSIONS: Ortho-k using the OK-74 lens design achieved an average myopia reduction of 1.50 D. The model developed can provide an estimate of the refractive change likely to occur in ortho-k, a matter of importance to both clinician and patient.

Journal Article↗
PubMed2002

[Implantation of phakic anterior chamber intraocular lens for high myopia]

OBJECTIVE: To investigate the efficacy and safety of the implantation of phakic anterior chamber intraocular lens for high myopia. METHODS: A consecutive group of 29 eyes in 16 patients with (-7.00 to -30.00) D of myopia were implanted. RESULTS: All of the 29 eyes were implanted successfully and followed-up 3 approximate, equals 6 months. The mean best corrected visual acuity was 0.50+/-0.26 pre-operatively and 0.73+/-0.263 months post-operatively, there was no significant difference t=2.043, P=0.051 . The mean refractive diopter was -18.03+/-5.54 D pre-operatively and -0.82+/-1.54 D post-operatively t=30.899 P=0.000 ; The mean intraocular pressure was 2.091+/-0.380 kPa pre-operatively and (1.734+/-0.572)kPa post-operatively t=1.98 P=0.07 ; The mean counts of endothelial cells was (2704+/-390 /mm2 pre-operatively and (2 519+/-278)/mm2 post-operatively (t=1.16 P=0.26). CONCLUSION: The implantation of phakic anterior chamber intraocular lens for high myopia is predictable, reversible and controllable with simple manipulation. Long- time following-up is still required.

Journal Article↗
PubMed2002

[Variation of the peripherin gene in Chinese with or without high myopia].

To analyze the relationship of the peripherin gene(PRPH, OMIM17071) mutations with high myopia,genomic DNA was collected from 180 probands with high myopia ( TTT(Phe21Phe,4/180), nt2138C-->G(IVS3,1/180), codon277 GCC-->ACC(Ala277Thr,8/180), codon237 CCA-->TCA (Arg237stop,1/180), codon292CCG-->CCA (Ala292Ala,1/180),codon361CUG-->CUC(Leu361Leu,12/180), codon369 AAA-->AAG(Lys369Lys,12/180),nt3331G-->C(IVS7,3/180)were detected in a number of probands as indicated in the blanket. Of the 8 variations one( codon 277,G-->A,Ala277Thr) is a missense mutation identified in 8 of the 180patients and one of 60 controls; The mutation of codon361 and codon 369 were synonymous one and linkage each other; Another one(codon237,CCA-->TCA,Arg237stop) is a heterozygous nonsense mutation identified in one patient with autosomal recessive inheritance mode population but not in the 60 normal controls. The others were synonymous mutations. Eight nucleotide variations were found in the PRPH gene. We found no evidence that mutations in the PRPH gene are responsible for the high myopia in Chinese.

English Abstract↗
PubMed2004

United States Food and Drug Administration clinical trial of the Implantable Collamer Lens (ICL) for moderate to high myopia: three-year follow-up.

PURPOSE: To report on 3-year postoperative safety and efficacy outcomes with the Myopic Implantable Collamer Lens (ICL). DESIGN: Prospective nonrandomized clinical trial. PARTICIPANTS: Five hundred twenty-six eyes of 294 patients with between 3.0 and 20.0 diopters (D) of myopia participating in the United States Food and Drug Administration clinical trial of the ICL for myopia. INTERVENTION: Implantation of the ICL. MAIN OUTCOME MEASURES: Uncorrected visual acuity (VA), refraction, best spectacle-corrected VA (BSCVA), adverse events, operative and postoperative complications, lens opacity analysis, subjective satisfaction, and patient symptoms. RESULTS: At 3 years, 59.3% had 20/20 or better VA, and 94.7% had 20/40 or better uncorrected VA if BSCVA was 20/20 and patients were targeted for emmetropia; 67.5% of patients were within 0.5 D and 88.2% were within 1.0 D of predicted refraction. The mean improvement in BSCVA ranged between 0.5 and 0.6 lines. At 3 years postoperatively, 3 eyes (0.8%) decreased by >or=2 lines of BSCVA, in contrast to 40 eyes (10.8%) that improved by a similar amount. Contrast sensitivity improved postoperatively. Cumulative 3-year corneal endothelial cell loss was under 10%. Early largely asymptomatic, presumably surgically induced anterior subcapsular opacities (trace or greater) were seen in 14 eyes (2.7%), with only 2 being clinically significant. Five eyes (0.9%) of 3 patients developed nuclear opacities of grade >2 at 2 to 3 years postoperatively. Three (0.6%) ICL removals with cataract extraction and IOL implantation have been performed. Only 0.6% reported dissatisfaction; 97.1% of patients reported they would choose ICL implantation again. Incidences of patient symptoms, glare, halos, double vision, night vision problems, and night driving difficulties decreased or remained unchanged after ICL surgery. CONCLUSION: Three-year results from this standardized, multicenter clinical investigation support the safety, efficacy, and predictability of ICL surgery to treat moderate to high myopic refractive errors.

Adult↗
PubMed2006

[Fundus oculi changes in myopia].

I. SIMPLE MYOPIA: Simple refractive error, which is not associated with fundus changes; Optical correction/refractive surgery brings the patient to visual acuity=1. II. DEGENERATIVE MYOPIA: Refractive error which is associated with fundus changes (during the "fundus changes" progression, the visual acuity is getting worse); Myopic fundus changes-classification: A/ RETINA: Posterior staphyloma Chorioretinal atrophy. Optic disc changes = 1-3. Macula changes (Myopic maculopathy) = 1-7. Peripheral fundus changes = 1-6. B/ VITREOUS: Fundus examination should be performed on any myopic patient; Fundus fluorescein angiography allows the objective follow-up of the fundus lesions and also the evaluation of the treatment results; Optical correction/refractive surgery cannot bring the patient to visual acuity=1, due to fundus lesions; For some lesions--which can generate serious visual complications, it is necessary prophylactic treatment by ARGON laser photocoagulation or cryotherapy.

Fluorescein Angiography↗
PubMed2000

A preliminary study of photodynamic therapy using verteporfin for choroidal neovascularization in pathologic myopia, ocular histoplasmosis syndrome, angioid streaks, and idiopathic causes.

OBJECTIVE: To evaluate short-term safety and the effects on visual acuity and fluorescein angiography of single or multiple sessions of photodynamic therapy with verteporfin for choroidal neovascularization (CNV) not related to age-related macular degeneration (AMD), including pathologic myopia, the ocular histoplasmosis syndrome, angioid streaks, and idiopathic causes. DESIGN: A nonrandomized, multicenter, open-label, dose-escalation phase 1 and 2 clinical trial. SETTING: Four ophthalmic centers in Europe and North America providing retinal care. PARTICIPANTS: Thirteen patients with subfoveal CNV due to pathologic myopia, the ocular histoplasmosis syndrome, angioid streaks, or idiopathic causes. METHODS: Standardized protocol refraction, visual acuity testing, ophthalmic examinations, color photographs, and fluorescein angiograms were used to evaluate the results of photodynamic therapy treatments with verteporfin. Follow-up ranged from 12 weeks for patients who were treated once to 43 weeks for patients who were treated up to 4 times. RESULTS: Verteporfin therapy was well tolerated in patients with CNV not related to AMD. No deterioration in visual acuity was observed; most patients gained at least 1 line of vision. Reduction in the size of leakage area from classic CNV was noted in all patients as early as 1 week after verteporfin therapy, with complete absence of leakage from classic CNV in almost half of the patients. Improvement in visual acuity after verteporfin therapy was greatest (+6, +8, and +9 lines) in 3 patients with relatively poor initial visual acuity (between 20/200 and 20/800). Up to 4 treatments were found to have short-term safety even with retreatment intervals as short as 4 weeks. CONCLUSIONS: Treatment of CNV not related to AMD with verteporfin therapy achieves short-term cessation of fluorescein leakage from CNV in a small number of patients without loss of vision. Further randomized clinical trials including a larger number of patients are under way to confirm whether verteporfin therapy is beneficial for subfoveal CNV not related to AMD.

Adult↗
PubMed2002

Clinical and theoretical results of intraocular lens power calculation for cataract surgery after photorefractive keratectomy for myopia.

OBJECTIVES: To describe the refractive results of cataract surgery after photorefractive keratectomy (PRK) for patients with myopia, and to find a more accurate method to predict intraocular lens (IOL) power in these cases. DESIGN: Nonrandomized, retrospective clinical study. PATIENTS AND METHODS: Nine patients (15 eyes) who underwent cataract surgery after prior PRK to correct myopia were identified. The medical records of both the laser and cataract surgery centers were reviewed. MAIN OUTCOME MEASURES: Eight different keratometric values (K values; measured or calculated) were entered into 3 different IOL calculation formulas: SRK/T, Holladay 1, and Hoffer Q. The actual biometry and IOL parameters were used to predict postoperative refraction, which was compared with the actual refractive outcome. Also, the relative underestimation of the refractive change in corneal dioptric power by keratometry after PRK was calculated. RESULTS: In 7 of 15 eyes, IOL exchange or piggybacking was performed because of hyperopia. Retrospectively, the most accurate K value for IOL calculation was found to be the pre-PRK K value corrected by the spectacle plane change in refraction. Use of the Hoffer Q formula would have avoided postoperative hyperopia in more cases than the other formulas. The mean underestimation of the change in corneal power after PRK varied from 42% to 74%, depending on the method of calculation. CONCLUSION: The predictability of IOL calculation for cataract surgery after PRK can be improved by using a corrected, refraction-derived K value instead of the measured, preoperative K value.

Adult↗
PubMed1987

Complications of clear lens extraction in axial myopia.

Clear lens extraction is a refractive surgery used to compensate axial myopia. Formerly, intracapsular lens extraction was performed, but the present surgical method is extracapsular lens extraction or phacoemulsification. Clear lens extraction is becoming controversial because of the danger of complications. We retrospectively reviewed the postoperative complications in 33 eyes of 20 patients who underwent clear lens extraction at other institutions between 1966 and 1984. Twelve patients (60%) had motility disturbances. Eight (24%) of 33 eyes suffered secondary glaucoma; ten (30%), retinal detachment; 12 (36%), lens remnants in the pupillary space; and six (18%), blindness caused by clear lens extraction or by additional surgery performed by us while attempting to improve a poor prognosis. Clear lens extraction appears to be contraindicated in the young, in those with axial diameters greater than 29 mm, and in those presenting with peripheral chorioretinal degeneration. Moreover, clear lens extraction does not avoid the progression of myopia at the posterior segment. We suggest the use of safer, noninvasive, reversible alternatives.

Adult↗
PubMed1988

Excimer laser keratectomy for myopia with a rotating-slit delivery system.

We performed argon fluoride excimer laser (193-nm) superficial keratectomy for myopia on human donor eyes and on a resected corneal disc. The laser beam was shaped by a rotating slit to produce a circular ablation 7.5 mm in diameter, with a mathematically defined profile to correct myopia. The fluence at the surface of the cornea was 200 mJ/cm2; the laser was fired at 20 Hz. Each 4.5-mJ laser pulse etched a 0.17-micron deep image of the slit in the cornea. Since the slit moved (0.03 Hz), each successive pulse etched an area adjacent to the previous one, reducing damage from repetitive pulses striking the same area. The slit scanned the cornea many times and the summation of these individual ablations produced the smooth myopic ablation profile, as shown by computerized keratographs and light and electron microscopy.

Cornea↗
PubMed1990

Central photorefractive keratectomy for myopia. The blind eye study.

Prior to undertaking a study in sighted human eyes, we performed photorefractive keratectomy with the 193-nm excimer laser for the correction of myopia in nine legally blind eyes to evaluate safety, efficacy, predictability, and stability. In most cases, reepithelialization was complete by 5 days after surgery; no recurrent erosions were seen. By the end of the 6-month study, all of the corneas had a 0 or 1+ clarity score, on a scale of 0 (clear) to 5+ (opaque). Keratometry and pachometry demonstrated stable flattening of the corneas. One month after surgery, changes in refraction evaluated by retinoscopy showed fair predictability, with no significant increase in refractive or keratometric astigmatism, followed by some regression of effect by the end of the study, possibly caused by anatomical remodeling. The amount of regression appeared to be directly related to the amount of correction intended, suggesting that this effect would not be clinically important in the treatment of mild to moderate myopia.

Adult↗
PubMed1994

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

OBJECTIVE: Excimer photorefractive keratectomy is a promising method to reduce myopia. We evaluated the effectiveness, predictability, stability, and safety of photorefractive keratectomy performed by two surgeons at a single site with a 1-year follow-up. METHODS: An excimer laser (Summit Excimed UV200, Summit Technology, Waltham, Mass) was used to treat 47 eyes. Preoperative uncorrected visual acuity averaged 20/277 and ranged from 20/60 to 20/500. Spherical equivalent averaged -3.9 diopters and ranged from -1.5 to -6.1 D. RESULTS: One year postoperatively, best corrected visual acuity averaged 20/13 and ranged from 20/10 to 20/20. No patients lost any of best corrected visual acuity. The uncorrected visual acuity at 1 year averaged 20/20 and ranged from 20/10 to 20/200. Ninety-four percent of eyes had an uncorrected visual acuity of 20/40 or better; 83%, 20/25 or better; and 74%, 20/20 or better. An initial hyperopic overcorrection is followed by gradual regression to emmetropia during a 12-month period. Refractive spherical equivalent averaged 0.44 D and ranged from -3 to +2.6 D at 1 year. The proportion of eyes within 1 D of emmetropia was 80% at 1 year. The most significant shifts in refraction occurred between the first and second months, but small shifts occurred up to 12 months. Subgrouping the results according to age revealed a significantly greater effect with larger residual hyperopia in those older than 40 years. Patient satisfaction with the procedure was high. CONCLUSION: During a 1-year period, excimer photorefractive keratectomy appears to be an effective, predictable, stable, and safe method to reduce myopia. Age may play a role in the effectiveness of the procedure, with greater hyperopia resulting in those older than 40 years.

Adult↗
PubMed1995

One-year evaluation of excimer laser photorefractive keratectomy for myopia and myopic astigmatism. Melbourne Excimer Laser Group.

OBJECTIVE: To evaluate prospectively the efficacy and safety of excimer laser photorefractive keratectomy in the treatment of myopia and myopic astigmatism. METHODS: Up to 15 diopters (D) of myopia with or without astigmatism of less than 6 D was treated with an excimer laser (VISX Twenty/Twenty). One hundred fifty procedures have been followed up for more than 12 months. RESULTS: Postoperative refractions were generally stable after 3 months without significant early overcorrection. Of those eyes treated with spherical equivalents of 5 D or less, 96% were within 1 D of the targeted refraction after photorefractive keratectomy and 88% had uncorrected visual acuities of 20/40 or better. At 12 months, 77% of all 150 eyes treated achieved an uncorrected visual acuity of 20/40 or better and 81% were within 1 D of the intended correction. Nine eyes (6%) lost 2 or more lines of best corrected visual acuity and 14 (9%) gained 2 or more lines. Adverse reactions were reported in 12 patients (8%) during the postoperative period. CONCLUSIONS: Photorefractive keratectomy is capable of correcting low and moderate myopic errors with a relatively high degree of accuracy and safety. The predictability and stability of the postoperative refraction during the first 12 months seem to be good.

Adult↗
PubMed1996

Discrete nuclear sclerosis in young patients with myopia.

OBJECTIVE: To review a series of young patients with myopia who had a visually disabling cataract. DESIGN: A retrospective review of 12 consecutive patients who had a visually disabling cataract and who were examined at the Cornea Service of the University of Illinois at Chicago. RESULTS: The mean age of the patients was 44 years (range, 34-54 years). The mean best-corrected visual acuity of the patients was 20/50, and the ocular history of the patients included a progressive decrease in vision. Six patients experienced disabling monocular polyopia. Their presumed diagnoses ranged from keratoconus to myopic degeneration. All of the patients noted resolution of their symptoms after cataract extraction. CONCLUSIONS: These patients are a select group that tends not to follow the established associations between visually significant lens opacities, age, and myopia. Cataract extraction is therapeutic, and prompt diagnosis can obviate unnecessary testing and repeated office visits.

Adult↗
PubMed1990

Neural control of eye growth and experimental myopia in primates.

Macaque monkeys become myopic when raised with fused lids to expose the retina to formless shadows during the period of postnatal eye development. The effect of the abnormal visual input is an excessive expansion of the posterior segment of the eye, a process that seems to be controlled by the nervous system. The mechanism by which the nervous system influences eye growth appears to be different in the stumptailed macaque (Macaca arctoides) and the rhesus macaque (M. mulatta). Lid-fused arctoides monkeys do not develop myopia when the ciliary muscle is paralysed or the optic nerve is cut, suggesting that the abnormal growth is caused by excessive accommodation. In contrast, paralysis of the ciliary muscle or optic nerve section does not prevent the development of myopia in the rhesus macaque, suggesting that in this species the axial growth is controlled by the retina. In both species neonatal lid fusion causes a marked increase in retinal vasoactive intestinal polypeptide (VIP). VIP is contained in a single type of amacrine cell whose dendrites spread in the middle of the inner plexiform layer. It remains to be determined whether the increase in the level of VIP is related to the abnormal axial elongation caused by lid fusion. At present we are also exploring the effects of accommodation on the growth of the eye by training juvenile arctoides monkeys to work on complex visual discrimination paradigms. Preliminary results show that performing a visual task at close range may influence the axial length and refraction in this macaque species.

Accommodation, Ocular↗
PubMed2005

Inference of nested variance components in a longitudinal myopia intervention trial.

This paper was motivated by a double-blind randomized clinical trial of myopia intervention. In addition to the primary goal of comparing treatment effects, we are concerned with the modelling of correlation that may come from two possible sources, one among the longitudinal observations and the other between measurements taken from both eyes per subject. The data are nested repeated measurements. We suggest three models for analysis. Each one expresses the correlation differently in various covariance structures. We articulate their differences and describe the implementations in estimation using commercial statistical software. The computer output can be further utilized to perform model selection with Schwarz criterion. Simulation studies are conducted to evaluate the performance under each model. Data of the myopia intervention trial are reanalysed with these models for illustration. The results indicate that atropine is more effective in reducing the progression rate, the rates are homogeneous across subjects, and, among the suggested models, the one with independent random effects of two eyes fits best. We conclude that model selection is a crucial step before making inference with estimates; otherwise the correlation may be attributed incorrectly to a different mechanism. The same conclusion applies to other variance components as well.

Analysis of Variance↗
PubMed1986

Familial sinus node disease and degenerative myopia--a new hereditary syndrome?

A family is reported in which the father and both offspring suffered from sick sinus syndrome (SSS) accompanied by degenerative myopia in the two elder of the three family members. In all three individuals, the basic manifestations of the SSS were total sinus arrest with secondary AV junctional rhythm at a normal rate. Only the 7-year-old boy also exhibited paroxysmal atrial flutter and ventricular asystole lasting up to almost 7 s. Since he had, furthermore, recently sustained a left hemiparesis, a ventricular demand pacemaker was implanted. Chronic atrial fibrillation was eventually established in the father in whom observations were available for 16 years. Myopia of -11 D and -4.5 D, respectively, existed in the father and his 14-year-old daughter. The familial association of this defect with SSS suggests a hitherto undescribed genetic syndrome, presumably with underlying autosomal dominant transmission of the two traits.

Adolescent↗
PubMed1993

Personality, psychophysical stress and myopia progression. A prospective study on 57 university students.

Personality profile, psychophysical stress and cycloplegic refraction were evaluated at the baseline (T0) and after 12 months (T1) in 57 university students comprising 39 myopes and 18 emmetropes/hyperopes (controls) whose age, sex distribution and academic results were comparable. At T0, a tendency toward a higher degree of anxiety, somatization and inadequacy was found in myopes in comparison with controls; however, only the anxiety state was different (Wilcoxon signed-rank test P < 0.001). Personality profiles, psychophysical stress and blood levels of cortisol, ACTH, GH, prolactin were similar in myopes and controls. The myopes were classified at T1 as either well-corrected (if their lenses corresponded to refractometer values of +/- 0.50 D and were worn full-time) or undercorrected (if their lenses were > or = 0.75 D with respect to refractometric values and/or were worn part-time). When the spherical cycloplegic values at T0 and T1 were compared, a myopic shift was revealed only in the undercorrected myopes (P < 0.001 in both eyes). These findings suggest that personality profile and psychophysical stress do not play a primary pathogenetic role in myopia. Undercorrection seems to accelerate the progression of myopia.

Adrenocorticotropic Hormone↗