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PubMedDate not supplied

Objective quality of vision in presbyopic and non-presbyopic patients after pseudoaccommodative advanced surface ablation.

PURPOSE: To analyze the objective quality of vision at 6 months postoperatively after pseudoaccommodative (presbyopic) advanced surface ablation (PASA). METHODS: The study comprised 62 eyes of 35 patients with 6-month follow-up that underwent primary or secondary treatments using PASA. Pre- and postoperative results of distance and near uncorrected visual acuity (UCVA), spherical aberration (coefficient of the Z12 Zernike polynomial), and the asphericity (Q) index were reviewed. The corresponding wavefront maps (total, low, and high order aberrations) and the corresponding point spread function and modulation transfer function (MTF) were also calculated. RESULTS: Our results show that PASA improves distance and near mean UCVA, increases negative spherical aberration and negative asphericity index, and improves the corresponding MTF. CONCLUSIONS: Pseudoaccommodative advanced surface ablation is a promising approach for the surgical correction of presbyopia with distance refractive error (myopia and hyperopia with or without astigmatism). This PASA technique could theoretically be used in non-presbyopic patients with refractive error or post cataract patients with monofocal intraocular lenses. The increase in negative spherical aberration and asphericity/eccentricity index seems to increase the depth of focus of the eye, improving the near vision and compensating the age-related lens changes. Rather than creating a multifocal cornea, PASA appears to create an improved aspheric (prolate) ablation profile.

Accommodation, Ocular↗
PubMed2000

Ophthalmologic abnormalities in mentally retarded.

PURPOSE: To determine the prevalence and types of ophthalmologic abnormalities in mentally retarded subjects. METHODS: Seventy-three institutionalized mentally retarded subjects (41 boys and 32 girls) aged 5 to 19 years (mean: 11.5 years) were examined ophthalmologically during a three month period (from May to July 1999). The eye examination consisted of visual acuity testing (illiterate Snellen E-chart or acuity card procedures), pupillary reflex and motility evaluation, cover test for phoria and tropia, examination of adnexa and anterior segment (magnifying glass or slit-lamp biomicroscopy if indicated and possible), retinoscopy and direct ophthalmoscopy. All subjects were evaluated pediatrically, neurologically, psychologically and otorhinolaryngologically if indicated. RESULTS: Ophthalmologic abnormalities were found in 60.2% of the subjects. Eyelid abnormalities accounted for 21.7%, fundus abnormalities for 21.6%, refractive errors for 15% and ocular motility disorders for 13.6%. Taken separately, optic atrophy (16.4%) was the most frequent disorder, followed by refractive errors (15%), hypertelorism (12.3%), epicanthus (10.9%) and nystagmus (8.2%). Strabismus and mongoloid obliquity of lids were seen in 5.4% each other while ptosis was disclosed in 4.2% of cases. Visual acuity tested in 60 subjects revealed that 25 (41.6%) had visual impairment. Of all subjects 10.9% required corrective glasses while 9.6% needed corrective surgery for strabismus and ptosis. CONCLUSION: This study shows a high prevalence of ophthalmologic abnormalities in mentally retarded subjects. This is in agreement with the results of several other previous studies. It's therefore essential to screen mentally disabled subjects ophthalmologically.

Adolescent↗
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↗
PubMed1993

Risk factors for idiopathic rhegmatogenous retinal detachment. The Eye Disease Case-Control Study Group.

The objective of this case-control study of idiopathic retinal detachment was to evaluate previously suggested hypotheses about risk factors for retinal detachment and to investigate whether new ocular or systemic risk factors could be identified. Between 1986 and 1990, data were obtained at five US clinical centers on 253 patients with idiopathic retinal detachment and 1,138 controls. Patients with pathologic myopia were excluded. Data were collected from interviews, clinical examinations, and laboratory analyses of blood samples. Only one clearly relevant risk factor, myopia, emerged from the analyses. An eye with a spherical equivalent refractive error of -1 to -3 diopters had a fourfold increased risk of retinal detachment compared with a nonmyopic eye; if the refractive error was greater than -3 diopters, the risk was increased 10-fold. The data suggest that almost 55% of nontraumatic detachments in eyes without previous surgery are attributable to myopia. The etiology of retinal detachment appears to be related to the architecture of the eye. The study found no evidence that systemic factors, particularly cardiovascular factors, play a role.

Adult↗
PubMed1996

Refractive surgery.

In recent years, there has been increasing interest in refractive surgery among patients and physicians. Refractive surgery lessens or eliminates the need for contact lenses or glasses. The goal of refractive surgery is to allow an individual more independence from optical devices. Technologic innovations have improved the predictability and safety of surgical correction of refractive errors and actually revolutionized treatment.

Humans↗
PubMed2005

Photorefractive keratectomy and laser in situ keratomileusis in refractive accommodative esotropia.

PURPOSE: To evaluate the efficacy of excimer laser refractive surgery as an alternative for optical correction in patients affected by fully refractive accommodative strabismus. SETTING: Eye Clinic, University of L'Aquila, L'Aquila, Italy. METHODS: After a simulation of the cycloplegic correction with contact lenses over a 30-day period, 18 patients (6 men, 12 women, mean age 32.4 years +/- 9.4 [SD]) affected by fully refractive accommodative esotropia had refractive surgery using an excimer laser; 8 patients had photorefractive keratectomy (PRK), and 10 patients had laser in situ keratomileusis (LASIK). RESULTS: The correction of the refractive error with excimer laser allowed a reduction of the angle of deviation in all but 1 patient, who presented with a regression of refractive error and of the angle of deviation 2 years posttreatment. The 2-year follow-up showed that the mean angle of deviation in PRK was 2(Delta) esophoria at near and 0.4(Delta) esophoria at distance (P<.06); in LASIK, it was 1.7(Delta) esophoria at near and 0.2(Delta) esophoria at distance (P<.06). The difference between the 2 groups was not statistically significant at near (P = .56), at distance (P = .74), or for spherical equivalent (P = .16). CONCLUSION: Excimer laser refractive surgery seems to be useful in the correction of fully refractive accommodative esotropia.

Accommodation, Ocular↗
PubMedDate not supplied

Hyperopic shift after 4-8 incision radial keratotomy: eight-year follow-up.

PURPOSE: To evaluate the prevalence, amount and possible factors connected with the hyperopic shift after radial keratotomy. BASIC PROCEDURES: We studied 86 eyes (51 patients) which underwent 4-8 incision radial keratotomy (delayed technique), consecutively performed by the same surgeon between February 1983 and November 1988. The diamond-bladed knife was set at 95% of the smallest paracentral ultrasonic corneal thickness measurement and the clear zone diameter was between 3.0 and 3.5 mm. Preoperative myopia ranged from -2.00 to -7.25 diopters (D). The average follow-up was 97.4 months (range 78 to 122 months). MAIN FINDINGS: After eight years of follow-up, the cycloplegic spherical equivalent was satisfactory: 66.2% of the eyes showed a refractive error within 0.5 D, 17.4% were myopic by more than 0.5 D and 16.2% were hyperopic by more than 0.5 D. The mean refractive error was 0.02 D (SD +/- 0.75 D). Between six months and eight years after surgery a hyperopic shift of more than 0.5 D was found in 40.6% of the eyes. The mean hyperopic shift was higher (0.78 D) in the eyes which had keratometry less than 36 D six months after surgery. Compared to the eyes with keratometry greater than 36 D (mean hyperopic shift 0.38 D), the difference was statistically significant (p < 0.02). CONCLUSIONS: These results show that keratometry, measured six months postoperatively, plays a fundamental role in the stability of postsurgical refraction, as the risk of hyperopic shift is higher in eyes with keratometry < 36 D.

Adult↗
PubMedDate not supplied

Predicting visual acuity in children with colobomas involving the optic nerve.

BACKGROUND: This study evaluates the relationship to visual acuity of four ophthalmoscopic features of colobomas involving the optic nerve. The goal was to identify those features that could predict potential visual acuity of children with these colobomas. METHODS: Fundus photographs of 23 eyes with colobomas involving the optic nerve met the entry criteria and were evaluated by two masked observers. The following features were evaluated: coloboma size, optic nerve color, foveal development, and subfoveal retinal pigment epithelial changes. Simple linear regression was used to identify the feature that most closely correlated with visual acuity. Refractive status was assessed by cycloplegic refraction. RESULTS: The only component that correlated with the development of good visual acuity was the degree of foveal involvement by the optic nerve coloboma (P = .002, R = 0.8). Significant refractive error and anisometropia were common in patients with colobomas involving the optic nerve. CONCLUSION: Central visual acuity in children born with colobomas involving the optic nerve correlates with the development of normal foveal anatomy, regardless of the size of the coloboma, the color of the optic nerve, or the presence of subfoveal pigmentary changes. Because refractive error is common, these children should receive an accurate refraction and amblyopia treatment.

Child, Preschool↗
PubMed2005

[Comparison of accuracy of refraction measurement in children up to the age of 15 years using the PowerRef II and by standard techniques].

OBJECTIVE: To establish whether refraction state in children up to the age of 15 years measured by photorefraction using PowerRef II device is comparable with values measured using common methods like skiascopy and autorefractor. Photorefraction is a quick method to determine refractive state from a distance without mydriasis and simultaneously in both eyes. It appears, therefore, to be a useful tool for measuring refractive errors of infants and older noncooperative subjects. However, its accuracy and reliability has been discussed. METHODS: In this study the authors assess accuracy of measurement of refractive errors by photorefraction in 40 children (19 boys, 21 girls) at the age ranging from 4 month to 15 years (average 4.8 years), divided according to their cooperation into two groups. The values of refraction acquired by photorefraction using PowerRef II device were compared with skiascopy in 23 noncooperative infants and with values of refraction from common autorefractor Nidek AR 600 in 17 cooperating children. RESULTS: Comparing results of both groups we have detected an average difference 0.41 D between skiascopy and photorefraction for spherical equivalents (0.45 for spheres, 0.42 for cylinders), average difference between spherical equivalents from autorefractor and photorefractor measurements was comparable: 0.52 D (0.51 for spheres, 0.55 for cylinders). CONCLUSION: Refractions measured by eccentric photorefraction with PowerRef II were comparable to those obtained by common methods of refraction measurement in children--i.e. skiascopy and autorefractor. Values of refraction were undervalued only in two cases of higher myopia during photorefraction measurement compared to autorefractor values. There was no significant shift by photorefraction measurement to myopic or hypermetropic values.

Adolescent↗
PubMed2005

Preliminary efficacy and safety of zero diopter lens implantation in highly myopic eyes.

PURPOSE: To report the preliminary efficacy and safety of zero diopter (D) intraocular lens implantation in highly myopic eyes. DESIGN: Retrospective surgical case series. METHODS: Three highly myopic eyes with axial lengths greater than 30 mm were implanted with zero D Alcon model MA60MA 3-piece acrylic posterior chamber lenses at the time of cataract surgery. RESULTS: Uncorrected visual acuity improved from counting fingers to 20/20- and 20/40- in two eyes. Best-corrected visual acuity improved from 20/80 and 20/60+ to 20/20- in the same eyes. A third eye was at counting fingers before and after surgery, because of a staphyloma. The range of preoperative, intended postoperative, and achieved postoperative spherical equivalent refractive errors was -15.1 to -25.0 diopters, -0.20 to -1.44 diopters, and +0.13 to +0.50 diopters respectively. CONCLUSIONS: All eyes experienced mild hyperopic refractive errors after surgery. No retinal detachments occurred during the follow-up interval.

Acrylic Resins↗
PubMed2004

Vision screening in schoolchildren: two years results.

OBJECTIVE: To assess the prevalence of visual impairment and ocular abnormalities among schoolchildren in Chiang Mai. DESIGN: A community-based survey. SUBJECTS AND METHOD: The vision screening project was conducted from June 2000 to March 2002. Students in grade I in the Chiang Mai municipal area were examined for visual acuity (VA), color vision, ocular alignment, anterior segment and fundus. Subjective refraction was done in students with subnormal vision (VA 20/30 or less). Referral to the hospital for further evaluation and treatment was made for students with strabismus, amblyopia and other ocular abnormalities. RESULTS: A total of 3,431 and 3,467 students were enrolled in 2000 and 2001, respectively. The prevalence of normal vision (VA 20/20), VA 20/30 or better in at least one eye and 20/40 or less in at least one eye were similar in both years (87%, 5.7%, 7.3% and 85%, 6.4%, 8.7%, respectively). There was no statistically significant difference in visual acuity among boys and girls in either year (p = 0.6 and p = 0.2). Prevalence of abnormal color vision was 4.2%. Other causes of visual impairment in both years included strabismus (1.5% and 6.2%), amblyopia (1.1% and 1.4%) and some congenital abnormalities. Most cases of amblyopia were due to uncorrected refractive errors. CONCLUSION: The authors found that over 10% of school-aged children had subnormal vision. The important causes of visual deterioration came from refractive errors, strabismus and amblyopia. The authors concluded that vision screening is a cost-effective way of reducing visual morbidity from preventable visual impairment, which is a tragedy that cannot be ignored.

Amblyopia↗
PubMed1993

Comparison of the accuracy of computerized videokeratography and keratometry for use in intraocular lens calculations.

We compared the accuracy of keratometry and computerized videokeratography (CVK) for use in intraocular lens calculations. We studied 48 eyes of 45 patients having phacoemulsification and posterior chamber lens implantation. Computerized videokeratography was performed with the EyeSys Corneal Analysis System (ECAS). Using the SRK II, SRK/T, and Holladay formulas, we evaluated predictive accuracy calculated with keratometric values and four values derived from ECAS measurements. For each formula, the use of one of the CVK parameters resulted in lower mean absolute errors between actual and predicted postoperative refractive errors and higher percentages of cases with power prediction errors < 0.5 and < 1.0 diopters. Computerized videokeratography may provide a more accurate corneal curvature value than keratometry for use in intraocular lens calculations.

Cataract Extraction↗
PubMed1992

The effects of pyridostigmine bromide on visual performance.

The effects of pyridostigmine bromide (PB) on selected visual functions were measured on four healthy aviator candidates. Following a pretreatment day during which baseline measurements were completed, subjects were administered currently recommended doses (30 mg, t.i.d.) of PB for 3 d during which their visual functions were assessed using a repeated measures design. Spatial resolution ability was evaluated with high and low contrast visual acuity charts and contrast sensitivity charts at three luminance levels. Dark adaptation was evaluated by measuring visual thresholds for 40 min after a standardized retinal photopigment bleach. Also, refractive error and several oculomotor functions (lateral phoria, fusional vergence, accommodative amplitude, and pupil size) were measured. On days that the subjects ingested PB, only refractive error and pupil diameter were significantly different, and these only minimally. We conclude that the use of PB at doctrinal doses will not significantly compromise an aviator's visual ability.

Accommodation, Ocular↗
PubMed1996

Diffuser contact lenses retard axial elongation in infant rhesus monkeys.

In each of five monkeys, one eye was fitted with a diffuser lens at birth. This lens allowed pattern vision, but also reduced contrast by about 1 log unit. In four out of five monkeys, the treated eyes were shorter and more hyperopic than the untreated fellow eyes. At 25 weeks of age, interocular differences (OD -- OS) of the experimental group were significantly greater than interocular differences of age-matched normal monkeys for both axial length (P < 0.05) and refractive error (P < 0.02). In addition, while the treated eyes were significantly different from normal eyes for both axial length measurements (P < 0.01) and refractive error (P < 0.01), there were no significant differences between the untreated fellow eyes and normal eyes. In primates less severe pattern deprivation appears to produce an effect on eye growth that is opposite to that of severe pattern deprivation (little or no pattern vision), which typically results in axial myopia.

Aging↗
PubMed1981

UCLA clinical trial of radial keratotomy. Preliminary report.

A clinical trail of radial keratotomy ws begun under a strict research protocol at the Jules Stein Eye Institute in November 1979. The results for the first 52 eyes undergoing radial keratotomy are reported three months after surgery. Preoperatively uncorrected visual acuity was less than 20/200 in all 52 eyes. and postoperative visual acuity was less than 20/200 in 11 eyes (21%). Three months postoperatively, uncorrected visual acuity was 20/40 or better in 27 eyes (52%) and 20/20 or better in 13 eyes (25%). Postoperatively the best-corrected visual acuity decreased in 10 eyes (20%), but maximum decrease in any eye was one line of snellen letters. Preoperatively mean refractive error was -4.9 (/+-2.2) diopters, and postoperatively the mean decrease in myopia was 3.4 (/+-2.2) diopters. Postoperatively 13 eyes (25%) had a hyperopic refractive error of +0.25 to +3.25 diopters, but all of these eyes were able to accommodate and obtain 20/20 visual acuity without glasses. Postoperatively there was no statistically significant change in axial length, anterior chamber depth, or scleral rigidity, but there was a mean corneal endothelial cell loss of 10% (P = 0.0002). Decrease in myopia achieved by radial keratotomy did not correlate with the steepness of corneal curvature, corneal diameter, or scleral rigidity. Three months after surgery, significant symptoms of glare were present in 10 eyes (20%0, and annoying variable visual acuity was noted in five eyes (10%).

Adult↗
PubMed1996

[Foveal cone densitometry in high myopia].

We performed foveal cone densitometry using a modified fundus camera in 17 eyes of 17 normal subjects (age range, 20 to 47 yr, refractive error, +2.0 to -2.5 D) and 15 eyes of 15 high myopia subjects with normal visual acuity (age range, 18 to 46 yr, refractive error, -9.0 to -14.5 D). After fully bleaching, the density of photopigment was measured for 7 minutes by a test spot of 562 nm in wavelength and 1 degree in diameter, focussed on the fovea. Two-way density and the time constant of pigment regeneration were calculated. No significant difference was found in two-way density between the two groups. The time constant in high myopia (161.6 +/- 36.6 sec), however, was significantly increased (p < 0.01), compared with normals (124.0 +/- 28.7 sec). To study the correlation of psychophysical visual function, we performed a photostress recovery test, which revealed a significant delay of the recovery time in high myopia (p < 0.01). These results suggest that a delay in foveal cone pigment kinetics precedes loss of cone cells or chorioretinal degeneration in high myopia.

Adolescent↗
PubMed1997

[Ophthalmoscopic assessment of the size of the optic nerve papilla].

PURPOSE: To examine whether the optic disc size can be measured with common ophthalmoscopic lenses. PATIENTS AND METHODS: The horizontal and vertical disc diameters in 125 eyes of 65 patients were measured ophthalmoscopically using a commercial slit lamp with adjustable length of the beam and a Volk 60 diopters lens or a Volk Superfield lens. The refractive error of the subjects ranged between -7.25 D and +3.25 D (mean +/- S.D.: -0.34 +/- 1.77). Based on these measurements we calculated the optic disc area by applying a modified formula for an ellipse, where area = horizontal diameter x vertical diameter x pi/4. Additionally, we measured planimetrically the horizontal and vertical diameters of the optic disc on color stereo disc photographs after correcting the ocular and camera magnification according to Littmann's method. RESULTS: The values of the horizontal and vertical disc diameters evaluated on the photographs were by factors of 1.0 and 1.5 larger than those values measured with the Volk 60 D lens, and the Volk Superfield lens, respectively. Taking into account these constant linear correction factors, the optic disc diameters as measured by the Volk 60 D lens and the Volk Superfield lens varied by 0.11 +/- 0.09 mm (5.9 +/- 5.1%), and 0.11 +/- 0.09 mm (5.9 +/- 4.9%), respectively, from the values measured on the photographs. The error for the ophthalmoscopic measurement of the disc diameters decreased slightly with increasing disc size. With highly myopic eyes excluded, it was independent of the refractive error. CONCLUSION: For clinical purposes, the optic disc and other structures of the posterior fundus can be determined by ophthalmoscopy using a slit lamp and commonly used ophthalmoscopical lenses.

Adult↗
PubMed2000

Reducing the progression of myopia with atropine: a long term cohort study of Olmsted County students.

BACKGROUND: Myopia is an important public health problem because it is common and is associated with increased risk for chorioretinal degeneration, retinal detachment, and other vision- threatening abnormalities. In animals, ocular elongation and myopia progression can be lessened with atropine treatment. This study provides information about progression of myopia and atropine therapy for myopia in humans. METHODS: A total of 214 residents of Olmsted County, Minnesota (118 girls and 96 boys, median age, 11 years; range 6 to 15 years) received atropine for myopia from 1967 through 1974. Control subjects were matched by age, sex, refractive error, and date of baseline examination to 194 of those receiving atropine. Duration of treatment with atropine ranged from 18 weeks to 11.5 years (median 3.5 years). RESULTS: Median followup from initial to last refraction in the atropine group (11.7 years) was similar to that in the control group (12.4 years). Photophobia and blurred vision were frequently reported, but no serious adverse effects were associated with atropine therapy. Mean myopia progression during atropine treatment adjusted for age and refractive error (0.05 diopters per year) was significantly less than that among control subjects (0.36 diopters per year)(P<.001). Final refractions standardized to the age of 20 years showed a greater mean level of myopia in the control group (3.78 diopters) than in the atropine group (2.79 diopters) (P<.001). CONCLUSIONS: The data support the view that atropine therapy is associated with decreased progression of myopia and that beneficial effects remain after treatment has been discontinued.

Adolescent↗