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Results for “Visual Acuity”

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At least 577 records · Page 32Linked to original sources

PubMed2006

[Comparison between self-reported quality of vision and visual acuity in a low-income elderly population in the city of São Paulo].

PURPOSE: Self-reported visual function questionnaires are becoming more common in clinical research. The purpose of this study is to evaluate and correlate self-reported visual function assessed by a visual function questionnaire with visual acuity. METHODS: 806 patients aged 60 years and older, who were included in an epidemiological eye study, were interviewed and present visual acuity for near and distance was taken; they also answered a visual function questionnaire. RESULTS: Weak correlations were found between self-reported visual function assessed by a visual function questionnaire and visual acuities for both distance and near. CONCLUSION: Self-reported visual function assessed by a visual function questionnaire did not correspond to visual acuity, nevertheless it can provide important information to the ophthalmologist.

Aged↗

PubMed1992

The Rotterdam C-chart: norm values for visual acuity and interocular differences in 5-year-old children.

Common C-charts are often not suitable for developmental studies and assessment of visual acuity in young and visual impaired children, because of unequal steps between lines, uncomparable crowding, inadequate number of large optotypes on the first line and ceiling effects. Therefore a new C-chart (the Rotterdam C-chart) was developed on which optotypes on successive lines decreased in 1/3-octave steps (0.1-log steps) and on which crowding was comparable over the entire chart. Norm values for binocular and monocular visual acuity at test distances of 6 m and 40 cm and norm values for interocular acuity differences in 5-year-old children were determined by testing 201 5-year-olds with this chart. Results were compared to those obtained in 24 young adults. Although mean binocular and monocular acuity of the 5-year-olds were significantly lower than in adults, the distribution of acuity assessments were similar in the children and adults. Therefore, the Rotterdam C-chart seems suitable for developmental studies and for the assessment of visual acuity in young and visually impaired children.

Adult↗

PubMed2004

Responsiveness of the SF-36 health survey to changes in visual acuity among patients with subfoveal choroidal neovascularization.

PURPOSE: To report the responsiveness of the SF-36 Health Survey to changes in visual acuity among patients with subfoveal choroidal neovascularization participating in the Submacular Surgery Trials pilot study. DESIGN: Cohort study. METHODS: Correlation analyses were used to explore relationships at each time point, and linear regression was used to determine the relation between the 2-year changes in SF-36 scores and visual acuity. RESULTS: A weak, but statistically significant, association was found between the 2-year changes in both the Physical Component Summary score and the Physical Functioning subscale with changes in visual acuity of the better eye. No association was found between changes in visual acuity and the Mental Component Summary score or the Mental Health subscale. CONCLUSIONS: The SF-36 summary scales and the individual subscales were minimally responsive to 2-year changes in visual acuity in this subgroup of patients.

Aged↗

PubMed1999

[Comparative evaluation of visual acuity after cataract extraction with monofocal, bifocal or progressive lenses implantation].

PURPOSE: Evaluation which of the lenses: monofocal, bifocal or progressive, assure the best visual acuity in patients. MATERIAL AND METHODS: 86 patients aged from 21 to 84 years were operated. Monofocal lenses were implanted in 30 cases, bifocal in 32 and progressive in 24 cases. RESULTS: In 90% of patients with monofocal lenses and over 90% of patients in the remaining groups full uncorrected or corrected distance visual acuity was achieved. In groups with bifocal and progressive lenses full near visual acuity without correction, or with the same correction as for distance, was achieved by respectively 65.5% and 75% of patients. CONCLUSIONS: In all three groups very good distance visual acuity was achieved. The best near visual acuity is assured by progressive lenses, in lower degree by bifocal lenses.

Adult↗

PubMed1990

[Trial on the objective evaluation of visual acuity and its maturation by the method of evoked visual potentials].

We have developed a method to estimate foveal visual acuity (VA) through analysis of VEPs. It consists in determining the smallest check size in a pattern reversal that elicits a significant cortical response. The VEP is regarded as significant if the P 100 amplitude reaches a pre-established level in the signal to noise ratio. A valid criterion to determine normal VEP-VA emerges from the testing of 84 emmetropic and ametropic eyes: within our stimulation and recording conditions, a significant VEP response to the reversal of seven minutes checks corresponds to normal foveal acuity. This criterion has also proved pertinent to discriminate between normal VAs of 20/20 and decreased VAs (20/40 or less) with four other groups of subjects: 14 adult eyes whose VAs of 20/20 are decreased through Bangerter occlusives, 32 emmetropic and ametropic eyes belonging to five-years-olds children, 28 emmetropic and ametropic eyes of twelve-years-olds. In order to guarantee the validity of our results we carried out a double-blind study with ophthalmologists. The relevance of the method we suggest is related to that of the method which consists in extrapolating the regression line between VEP amplitudes and the pattern element sizes. At least we have aimed at establishing VEP norms for the maturation of VA. We have collected data from the following subjects: 5 infants tested monthly between 1 and 6 months, 31 infants ranging in age from 1 to 16 months, 10 five-year-old children, 13 twelve-year-olds, and 11 subjects aged 20. Within our stimulation and recording conditions a significant evoked response to the reversal of seven minute checks can be observed from 8 months onward. With an eight-month-old infant this response to the reversal of seven minute checks cannot be identified to the same response with an adult. There are two major differences: the latency of the major positive component is longer, and the structure of the evoked response consists of fewer components.

Adult↗

PubMed1995

Visual acuity modeling using optical raytracing of schematic eyes.

PURPOSE: We developed a methodology to predict changes in visual performance that result from changes in the optical properties of the eye. METHODS: Exact raytracing of schematic eyes was used to calculate the point spread function and the modulation transfer function of the visual system. The Stiles-Crawford effect, photopic response, diffraction, and the retinal contrast sensitivity are included in the model. Visual acuity was predicted by examining the modulation of the resultant retinal image of a bar target and by determining when the modulation falls below a threshold value. Visual acuity was predicted for refractive errors ranging from 0 to 5 diopters and for pupil diameters ranging from 0.5 to 8 mm. RESULTS: Visual acuity predictions were compared to clinically found Snellen visual acuities and were found to be highly correlated (r2 = .909). CONCLUSIONS: This modeling technique shows promise as a means of evaluating clinical and surgical procedures before undertaking clinical trails.

Contrast Sensitivity↗

PubMedDate not supplied

Time course of changes in retinal thickness and visual acuity after intravitreal triamcinolone acetonide for diffuse diabetic macular edema with and without previous macular laser treatment.

PURPOSE: To describe the changes in retinal thickness (RT) and visual acuity over time in patients with clinically significant diffuse diabetic macular edema (DME) after intravitreal injection of triamcinolone acetonide (IVTA) and to compare patients with and without previous laser treatment. METHODS: A total of 23 eyes with clinically significant DME received a 4-mg IVTA injection. Twelve eyes were refractory to macular laser treatment (group 1), and 11 eyes received IVTA as primary therapy (group 2). Visual acuity and changes in macular thickening shown by optical coherence tomography were evaluated 48 hours after injection, every 7 days for 1 month, and at 3 months and 6 months of follow-up. RESULTS: RT decreased in all eyes in both groups. The reduction of edema was maximal in the first 7 days after IVTA and tended to remain stable for 3 months. The decrease in RT over time was significant in both groups (P < 0.001). At 6 months, RT had increased in almost all eyes. Visual acuity improved quickly, to a maximum at 2 weeks in both groups, after which it remained stable for 3 months and then decreased. Improvement in visual acuity over time was significant in both groups (P < 0.001). The temporal characteristics of the changes in RT and visual acuity were similar in the two groups (P < 0.05). CONCLUSIONS: IVTA was effective in reducing clinically significant DME and improving visual acuity in eyes with and without previous laser treatment. Its action was maximal in the first week and lasted approximately 3 months in this study.

Adult↗

PubMed2004

Subnormal visual acuity (SVAS) and albinism in Mexican 12-13-year-old children.

BACKGROUND: In a previous study the vision of 1046 12-13-year-olds in Sweden was examined. Of those 67 had some kind of visual disturbances and in 20 no obvious cause was found. In this group, defined as children with subnormal visual acuity syndromes (SVAS), albinism was shown to be a major cause to the visual dysfunction giving a prevalence of about 1%. This is about 100 times higher than previous figures. Albinism can therefore be the cause in many cases of unexplained low visual acuity, at least in Sweden. Subnormal visual acuity is usually found in 2-4% in a pediatric population and is often called 'amblyopia'. The Swedish study showed that in many cases 'amblyopia' should be replaced by 'SVAS' and further investigation. The present Mexican study was designed identically to the Swedish study. The objective was to describe the distribution of visual acuity and the prevalence of ocular disorders, including incidence of subnormal visual acuity (SVAS) and the occurrence of albinism in a Mexican population of 12-13-year-olds. SUBJECTS AND METHODS: Altogether 1035 children, 12-13 years of age, were examined. A total number of 344 children were referred to the university pediatric eye clinic for further examination. 272 of these had simple refractive errors, 59 were diagnosed with an ophthalmological disorder and 13 children could not be pathologically classified. These were referred to a second ophthalmological examination, including VEP (Visual Evoked Potential) recordings. VEP reveals an asymmetric (right vs. left) cortical response after monocular stimulation in albinism. RESULTS: No child showed iris translucency or any other typical albinoic sign. VEP was recorded from 11 children. Three children showed an asymmetric VEP and were classified as albinos. The VEP response was normal in 8 of the children. CONCLUSIONS: The results indicate that albinism is common in Mexico, although not as common as in a similar Swedish population. A prevalence of albinism of approximately 0.3% was found in the Mexican population, compared to approximately 1% in the Swedish study group. The number of albinos was much higher in both study groups than to be expected from previous estimates. The difference between the Swedish and the Mexican figures may be explained by the general difference in pigmentation between Sweden and Mexico and thus probably by the subsequent lower number of commonly occurring albino foci in the Mexican heritage. It is emphasised that in investigations of children with SVAS, also in countries with a generally high pigmentation level, electro-physiological examinations are important, to be able to reveal albinism, but also to exclude or verify other conditions in the SVAS group, for example neurometabolic conditions.

Adolescent↗

PubMed1994

[Visual acuity and central retinal sensitivity following removal of epimacular membrane].

We evaluated visual acuity and central retinal sensitivity after removal of the epimacular membrane to explore whether and how the visual outcome differs between idiopathic disease (seven cases) and secondary disease following rhegmatogenous retinal detachment surgery (seven cases). A 12-month follow-up study revealed that both the idiopathic and the secondary group showed a marked improvement in visual acuity during the initial six months, followed by a slight decrease. As regards the central retinal sensitivity as assessed by an Octopus automated perimeter, the idiopathic group remained unchanged, but the secondary group showed a gradual improvement. In addition, postoperative visual acuity in the secondary group appeared to correlate with the preoperative central retinal sensitivity. Preoperative assessment of preoperative retinal sensitivity may provide a means of predicting postoperative visual outcome.

Contrast Sensitivity↗

PubMed2002

[Preoperative factors influencing visual acuity following vitrectomy for exudative age-related macular degeneration].

PURPOSE: We investigated the relations between ingrowth site and visual results in patients undergoing surgical removal of subfoveal choroidal neovascular membranes (CNV) caused by age-related macular degeneration (AMD). MATERIALS AND METHODS: The subjects were 70 eyes(69 patients), which underwent surgical removal of CNV for AMD and were followed up for 6 months or more. The eligibility criteria were active subfoveal choroidal neovascular membrane 3 disc diameters (DD) or less in size located above the retinal pigment epithelium, and visual acuity of 0.3 or worse. We analyzed the relationships between postoperative best-corrected visual acuity and preoperative factors: ingrowth site of CNV, distance between the fovea and the CNV edge, CNV size, and fluorescence pattern in indocyanine green angiography (IA). RESULTS: Patients 1) with feeder vessels located outside the foveal avascular zone (FAZ) rather than inside the FAZ and/or unknown feeder vessels, 2) with a distance between the fovea and the CNV edge 0.2 DD or less than 0.2 DD versus larger, than 0.2 DD 3) with a 1 DD or smaller CNV versus 1.5 DD or larger, and 4) type I, II, or III findings in IA rather than type IV had good postoperative best-corrected visual acuity. CONCLUSIONS: To achieve better postoperative visual acuity after surgical removal of CNV associated with AMD, it is important to select CNV with ingrowth sites outside the FAZ, small and large CNV with a relatively short distance between the fovea and the CNV edge closest to the fovea, and type I, II, and III findings in IA.

Aged↗

PubMed1998

Assessment of high and low contrast visual acuity after photorefractive keratectomy for myopia.

BACKGROUND: Our aim was to assess visual acuity using standardized charts and illumination conditions after photorefractive keratectomy. METHODS: High and low contrast visual acuity were measured on Bailey-Lovie logarithm of the minimum angle of resolution (LogMAR) charts under high and low illumination conditions on 105 photorefractive keratectomy patients who had been treated with the Summit (N = 60) or the VISX (N = 45) excimer laser. RESULTS: Best corrected visual acuity was reduced in the treated eye compared with the untreated control eye under all test conditions, with the greatest differences under conditions of low contrast and low illumination. Reduction of acuity under low contrast and low illumination was related to small optic zone sizes and steep ablation edge profiles found in Summit-treated eyes. In the VISX-treated eyes, high contrast acuity was reduced in the presence of central topographical irregularities, subepithelial haze, and higher myopic corrections. CONCLUSIONS: Testing conditions such as those described here may be useful in quantifying vision degradation in suboptimal viewing conditions and among patients with vague complaints.

Adult↗

PubMed1980

Aphakic keratoplasty: visual acuity and optical errors.

Sixty-four consecutive patients with aphakic penetrating keratoplasty and penetrating keratoplasty combined with intracapsular cataract extraction were reviewed in a prospective fashion with a minimum of a one-year follow-up. Five were lost to follow-up. There were seven graft failures at the end of one year. Five of these were from 11 patients who underwent second operations because of failed grafts. Visual acuity was 20/80 or better in 29 of the patients. Pathology accounted for decreased visual acuity in all of those with visual acuity less then 20/80. Problems wre macular degeneration in 11 of the 23 patients with poor visual acuity (48%); marked cystoid macular edema in four patients (17%), advanced glaucoma in three patients (13%) and amblyopia in three patients (13%). Graft size had no significant effect on visual acuity. In terms of the final refractive error and astigmatism, there were no significant differences seen in those in whom a larger donor was used compared with those in whom a donor the same size as the recipient opening was used. Aphakic penetrating keratoplasty has shown outstanding technical success with poor visual acuity representing a difficulty in screening for non-corneal pathology. With an otherwise normal eye, the chances for excellent optical success are very good at the present time with modern techniques in aphakic penetrating keratoplasty.

Aphakia↗

PubMed1990

Objective visual acuity testing by optokinetic nystagmus suppression.

The features of optokinetic nystagmus (OKN) suppression were investigated in various kinds of visual disturbances including those of optical, retinal, higher cortical and psychogenic etiologies. A new OKN suppression device was developed, modifying the principle of Ohm. Objective visual acuities were calculated using the visual angle of OKN suppression dots which were arranged in 12 steps corresponding to the visual acuity from 0.03 to 1.0 as determined by Landolt's method. A total of 286 cases were tested. Results were classified into four types of coincidence between objective and subjective visual acuities. The first group showed equivalent acuities. Normal subjects, cases of corneal opacity, aphakia with intraocular lens implantation and functional amblyopia belonged to this category. In the second group, objective acuity could not be determined because of fixation disturbance due to cortical lesion. The subjective acuity better than the objective acuity was obtained in the third group which consisted of cases with macular hole, central serous retinopathy and optic neuritis with central scotoma. Disturbance of foveal fixation to the OKN suppression dot seemed to be the reason for this difference in the acuities. In the fourth group, the objective acuity was better than the subjective acuity. This occurred in cases of psychogenic visual disturbance and malingerer.

Adolescent↗

PubMed1986

Dark-adapted foveal thresholds and visual acuity in retinitis pigmentosa.

To determine the relationship of foveal absolute thresholds to visual acuity in retinitis pigmentosa, we measured thresholds in 40 patients with various forms of retinitis pigmentosa (including Usher's syndrome) whose Snellen visual acuities were 20/30 or better. At all visual acuity levels, the patients' foveal thresholds were significantly higher than those of 20 similarly aged normal observers; threshold elevations tended to be greater for a 500-nm than for a 655-nm test flash. Foveal cone spatial summation functions were normal (test flash diameter range, 7' to 1.7 degrees), indicating that the patients' threshold elevations did not result from altered summation properties. A significant correlation between foveal cone thresholds and the midpoints of the patients' Rayleigh matches demonstrated that the threshold elevations resulted in part from a decreased cone optical density.

Adolescent↗

PubMed2005

Drug-induced intraocular lens movement and near visual acuity after AcrySof intraocular lens implantation.

PURPOSE: To evaluate the factors influencing AcrySof intraocular lens (IOL) (Alcon Laboratories) movement and near visual acuity after cyclopentolate 1% and pilocarpine 2%. SETTING: Department of Ophthalmology, University of Ankara, Ankara, Turkey. METHODS: Thirty eyes of 22 patients with AcrySof IOL implantation were included in this prospective study. Near visual acuity (Jaeger) at 35 cm through best distance correction without an add and pupil diameter were measured and correlated with anterior chamber depth (ACD) measured with ultrasound biomicroscopy (UBM) after application of cyclopentolate 1% and pilocarpine 2%, respectively. The magnitude of the change in the ACD was correlated with the accommodation amplitude, patient age, time interval between surgery and imaging, preoperative axial length, capsulorhexis diameter, ACD during cycloplegia, IOL diameter, and presence of posterior capsule opacification (PCO). RESULTS: Near visual acuity significantly decreased after application of cyclopentolate 1% and increased after application of pilocarpine 2% (P < .001) in all eyes. The IOL moved anteriorly in 8 (26%) eyes and posteriorly in 22 (74%) eyes after pilocarpine 2%. There was no correlation between the ACD and near visual acuity under cyclopentolate 1% (r = 0.06, P > .05) or pilocarpine 2% (r = 0.04, P > .05). There was a moderate correlation between the anterior IOL movement and accommodation amplitude (P < .05, r = 0.42). There was no correlation between the magnitude of the IOL movement and patient age, time interval between surgery and imaging, the preoperative axial length, capsulorhexis diameter, ACD during cycloplegia, IOL diameter, and the presence of PCO (P > .05). CONCLUSIONS: There was better near visual acuity in all eyes with the AcrySof MAIOL, although most IOLs move slightly backward after of pilocarpine 2%. This points out pseudoaccommodation rather than pseudophakic accommodation. Ultrasound biomicroscopy is useful in determining the ACD and the relation between the IOL and the surrounding tissues after cataract surgery.

Accommodation, Ocular↗

PubMed1998

Vitrectomy in patients with decreased visual acuity secondary to asteroid hyalosis.

PURPOSE: To evaluate the role of vitrectomy in patients with decreased visual acuity solely attributable to asteroid hyalosis. METHOD: We retrospectively reviewed the records of patients with asteroid hyalosis and identified those who underwent vitrectomy for symptomatic asteroid hyalosis alone. RESULTS: After vitrectomy, nine of 10 eyes (10 patients) had at least 1 line of improvement in nonstandardized best-corrected visual acuity. In one eye, vision was unchanged postoperatively. The average gain was 3.44 lines. CONCLUSIONS: A small percentage of patients with asteroid hyalosis have decreased visual acuity caused solely or primarily by the asteroid hyalosis. Vitrectomy in these patients may alleviate symptoms and improve visual acuity.

Aged↗

PubMed2003

[Natural course and prognosis of visual acuity in patients of age-related macular degeneration with occult choroidal neovascularization].

OBJECTIVE: To investigate the natural course and the final visual acuity in patients of age-related macular degeneration with choroidal neovascularization. METHODS: Thirty five eyes of 29 patients diagnosed as AMD with occult choroidal neovascularization were studied. The eyes which had laser, radiation therapy or surgical treatment were excluded. Visual acuity, fundus examination, fluorescent angiography (FFA) and perimetry test were performed at the first time visit and 5 years following-up at an interval of 1 to 3 months. The average following-up period of time was 8 years (range from 5 to 16 years) which started in 1985 and ended in 2001. RESULTS: Initial visual acuity 0.1 or less was shown in 10 eyes (28.5%, only hands movement can be seen in 4 of 10 eyes), 23 eyes (65.7%) with visual acuity of 0.1 or less (14 eyes with vision acuity of hands movement) on the last visit. 7 of 35 eyes, the final visual acuity improved more than 2 lines, 12 eyes remained the same and 16 eyes had been lost vision more than two lines. At the baseline examination, 25 eyes had macular hemorrhages and 4 eyes had vitreous hemorrhages. The fundus hemorrhages occurred repeatedly 1 to 4 times in 23 eyes during following-up, the macular hemorrhages was detected in 7 eyes at the last visit. At the initial fundus examination, fibrotic membranes were found in 7 eyes; all 35 eyes had disc form scarring with various size in most recent following-up. CONCLUSION: The natural course of Age-related macular degeneration with choroidal neovascularization is prolonged and the final visual prognosis was poor especially in the cases with recurrent macular hemorrhages.

Age Factors↗

PubMed2004

Improvement of visual acuity caused by opticochiasmal astrocytoma after treatment for associated hydrocephalus--case report.

A 33-year-old male presented with syncopal attacks. He had a history of slowly progressive deterioration of visual acuity in both eyes. His visual deterioration began in the left eye at age 12 years and in the right eye at age 20 years. His left eye was completely blind by age 33 years. He had received no prior treatment for these visual disturbances. Magnetic resonance (MR) imaging on admission showed a large tumor with inhomogeneous intensity occupying the bilateral optic canals and orbital cavities, with extension to parasellar region. Arachnoid cysts were found in the left middle fossa and supracerebellar space, which had caused herniation of the cerebellar tonsils to the foramen magnum. Open biopsy and histology verified that the tumor was pilocytic astrocytoma. Arachnoid cysts associated with the hydrocephalus were treated with a ventriculoperitoneal shunt. Seven years after surgery, visual acuity of the right eye had improved although the left eye remained blind. Follow-up MR imaging demonstrated marked reduction in size of the ventricles and arachnoid cysts, but the tumor size did not change. This case illustrates the benign nature of low-grade glioma in this region in spite of the large size and long history. Deterioration of visual acuity may be reversible in some cases of opticochiasmal astrocytoma. In our case, the improvement in visual acuity probably resulted from growth arrest of the tumor and improvement in the dynamics of cerebrospinal fluid flow.

Adult↗