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At least 1,243 records · Page 69Linked to original sources
PubMed1990

Visual acuity estimates in noncommunicative elderly persons.

The acuity card procedure has been shown to provide reliable grating acuity estimates in pediatric patients. The current study was conducted to determine the usefulness of this procedure in another group of persons in whom conventional acuity measurements are not possible, ie, nursing home residents who suffer from dementing disorders. Binocular visual acuity estimates were obtained in 13 cognitively impaired nursing home residents. Test sessions took 20-30 min each. Both test-retest agreement and inter-observer agreement of Teller Acuity Card (TAC) acuity estimates were good (within 0.5 octave for all residents), demonstrating that this procedure yields reasonable acuity estimates in noncommunicative nursing home residents. The authors stress the potential of this tool for nursing home administrators as well as for researchers.

Aged↗
PubMed2000

Behavioral assessment of visual acuity in mice and rats.

We have developed a simple computer-based discrimination task that enables the quick determination of visual acuities in rodents. A grating is displayed randomly on one of two monitors at the wide end of a trapezoidal-shaped tank containing shallow water. Animals are trained to swim toward the screens, and at a fixed distance, choose the screen displaying the grating and escape to a submerged platform hidden below it. Both mice and rats learn the task quickly. Performance falls below 70% when the spatial frequency is increased beyond 0.5 cycles in most C57BU6 mice, and around 1.0 cycles per degree (cpd) in Long-Evans rats.

Adaptation, Physiological↗
PubMed1993

'Correctable undetected visual acuity deficit' in patients aged 65 and over attending an accident and emergency department.

The rate of occurrence of correctable undetected visual acuity deficit (CUVAD) in a population of patients aged 65 and over was investigated, using a pinhole screening method, to compare the sociodemographic and optical eye care habits of patients with or without a functionally significant CUVAD. Of 136 patients 46 (34%) were found to have a functionally significant CUVAD in one or both eyes which was not significantly associated with optician or general practitioner contact, age, sex, social class, living situation, or number of medications. Half the patients with significant CUVAD had not attended for 2 years mainly because of financial considerations. Three quarters attended of their own volition; only one in seven were prompted by opticians' postal invitations. It was concluded that a significant degree of CUVAD could be detected using a simple procedure which can be carried out by general practitioners as part of their general elderly health screen.

Aged↗
PubMed1998

[Objective assessment of minimum visual acuity by suppression of optokinetic nystagmus].

PURPOSE: To develop and to validate an objective method which allows an estimation of the visual acuity (VA) of adults. METHODS: A horizontal optokinetic nystagmus (OKN) was elicited by a vertical rectangular grating presented on a PC-screen and was recorded by an infrared reflection method. Superimposition of three stationary black detection stimuli was used to suppress the OKN. The size of these stimuli was increased every two seconds, in ten steps. Suppression of the OKN was taken as an indication that the stimuli were detected. The relation between the smallest effective stimulus and logVA was evaluated in 65 healthy volunteers (130 eyes) with artificially reduced VA and 425 cooperative patients (842 eyes) whose VA was reduced due to different etiologies. The tolerance intervals of logVA related to the discrete detection stimuli were calculated. RESULTS: The method allows an estimation of the least expectable VA in steps of 0.8, 0.32, 0.25, 0.12, 0.1, 0.06, 0.03 und 0.025 due to the smallest value of three trials. The least VA of strabismic amblyopic eyes can only be estimated in steps of 0.16, 0.06, and 0.02. A VA > 0.02 can be proven with high reliability. CONCLUSION: The method allows a clinically useful, objective estimation of the least VA without observer bias in non-amblyopic eyes.

Adolescent↗
PubMed2004

Vitrectomy and radial optic neurotomy for central retinal vein occlusion: effects on visual acuity and macular anatomy.

BACKGROUND: Central retinal vein occlusion (CRVO) is a common retinal vascular disorder and a leading cause of visual loss. It is thought to arise from vascular obstruction at the level of the lamina cribrosa. The purpose of the study reported here was to evaluate the potential benefit of radial optic neurotomy (RON) and determine its effect on foveal thickness and macular volume in patients with CRVO. METHODS: We conducted a prospective pilot study of ten patients with CRVO. Visual acuity (VA) score measured with the Early Treatment Diabetic Retinopathy Study chart and the corresponding Snellen equivalent were assessed before and 6 months after surgery. Colour fundus photography, fluorescein angiography (FA) and optical coherence tomography (OCT) were carried out before and at 2, 6, 12 and 24 weeks after surgery. Foveal thickness and macular volumes were assessed using OCT. RESULTS: Visible reperfusion was observed in four of the ten patients at the time of surgery. VA score improved in eight of the ten patients from a median score of 11.50 (range 0-68) to a median score of 35.00 (range 3-79). Macular volumes decreased in six of seven patients from a median of 4.99 mm3 (range 2.68-6.77) to a median of 3.11 mm3 (range 1.11-5.02). Foveal thickness decreased in six of seven patients from a median of 596.50 microm (range 338.50-745.50) to a median of 330.50 microm (range 118-634.50). Six of ten patients developed a chorioretinal venous anastomosis. Macular oedema on OCT persisted in six of ten patients. CONCLUSIONS: We observed an improvement in VA score and a corresponding reduction in foveal thickness and macular volume following RON, but macular oedema persisted in 60% of patients. Whilst optimisation of patient selection criteria remains a challenge, this pilot study suggests that RON has a beneficial effect on VA in patients presenting with CRVO.

Adult↗
PubMed2003

Evaluating a new logMAR chart designed to improve visual acuity assessment in population-based surveys.

AIMS: This study aimed to evaluate a new chart designed to improve the collection of visual acuity data in population-based surveys. The Reduced logMAR E chart (RLME) employs three letters per line, 'tumbling E' optotypes, and conforms to accepted contemporary design principles. METHODS: The performance of the chart was assessed within a population-based glaucoma survey in Thailand. Performance indices were test-retest variability (TRV) and agreement with acuity data measured using the ETDRS logMAR chart which acted as the 'gold standard'. RESULTS: The 95% confidence limits for TRV of RLME acuity data were +/-0.15 logMAR. This figure is consistent with published data on the TRV of acuities measured using five-letter-per-line logMAR charts. The mean difference between RLME and ETDRS acuity data was 0.00 logMAR (95% confidence intervals of +/-0.05 logMAR) indicating that RLME acuities agreed well with those of the ETDRS chart. The chart and its method of use was readily accepted by the local ancillary staff who required only minimal training before acuity measurement could be delegated to them. CONCLUSIONS: The study demonstrated that the RLME chart is capable of accurate and repeatable acuity measurements. Certain aspects of the design of the RLME chart may be particularly pertinent to the measurement of vision in population-based surveys.

Aged↗
PubMed1987

A new Snellen's visual acuity chart with 'Indian' numerals.

'Indian' numerals, which are popular among the Arab population, were used to devise a new Snellen's visual acuity chart. The new chart has the advantages of a reading chart. It keeps the patient's interest, does not miss alexic patients, and is quicker to perform. It is also devoid of the many disadvantages of a kinetic response chart (the capital E letter or Landolt's broken rings), especially that of the limited option of test objects.

Adolescent↗
PubMed1994

Measurement of night vision goggle (NVG) visual acuity with the NVG resolution chart.

Night vision goggles (NVG) operations are characterized as stressful with high task loading. Any reduction in goggle or visual performance which goes undetected can have a serious effect on flight safety and operational capability. The NVG Test Lane, with its resolution chart, provides an effective cost-efficient method for aircrew members to quickly evaluate the correct positioning and focusing of their NVG's prior to each mission. This evaluation validated the ability of the NVG resolution chart to produce the same performance results as a more detailed psychophysical procedure. NVG visual acuity was measured for five subjects (four pilots and one non-pilot) with two different night vision goggles. The results supported that there is no statistical difference between the results obtained with the individual target format and the 3 x 3 format. Additionally, the pilots with current NVG experience were able to obtain a significantly better acuity level than were those without current NVG experience.

Adult↗
PubMed1985

Visual acuity screening of children 6 months to 3 years of age.

The operant preferential looking (OPL) procedure allows a behavioral estimate of visual acuity to be obtained from children 6 mo to 3 yr of age. In clinical settings, there is often too little time available to obtain an acuity estimate with the standard OPL procedure. The goal of this study was to identify specific spatial frequencies, termed diagnostic grating frequencies, that could enable the OPL technique to be used as a screening procedure under conditions where completion of acuity estimation was not possible. One hundred eighty presumptively normal children, 6, 12, 18, 24, 30, and 36 mo of age, were each tested with up to 20 trials of a potential diagnostic grating frequency to determine the highest spatial frequency grating that could be resolved by 90% of children at each age. For all ages except 18 mo, there existed a spatial frequency that produced uniformly high OPL performance within the age group; this spatial frequency was separated by one-half to one octave from a higher spatial frequency that more than 30% of children at that age failed to detect. These results suggest that at all ages except 18 mo, it should be possible to use the OPL procedure as a vision screening tool by testing individual children with the diagnostic grating frequency appropriate for their age.

Child, Preschool↗
PubMed2006

Visual acuity and optical parameters in progressive-power lenses.

PURPOSES: The purposes of this study are to explore the effect of astigmatism and high-order aberrations of progressive-power lenses (PPLs) on visual acuity (VA) and to find a good optical metric for evaluating visual performance of PPLs. METHODS: A Hartmann-Shack (HS) wavefront sensor was used to measure PPLs and human eyes either independently or in combination. An additional channel permits the measurement of VA under the same optical conditions. Measurements were taken in six relevant locations of a PPL and in three eyes of different normal subjects. In every case, we obtained the wavefront aberration as Zernike polynomials expansions, the root mean square (RMS) error, and two metrics on point spread function (PSF): Strehl ratio and the common logarithm of the volume under the PSF normalized to one (Log_Vol_PSF). RESULTS: Aberration coupling of the PPL with the eye tends to equalize the retinal image quality between central and peripheral zones of the progressive lenses. In the corridor of the PPL, the combination of small amounts of coma, trefoil, and astigmatism (total RMS 0.1 mum) does not significantly affect VA. The continuous increase of astigmatism from corridor to outside zones reduces moderately the quality of vision. The highest correlations between optical metrics and VA were found for Log_Vol_PSF of the entire system eye plus PPL. CONCLUSIONS: Ocular aberrations reduce optical quality difference between corridor and peripheral zones of PPLs. In the same way, VA through the corridor is similar to that of eyes without a lens and it decreases slowly toward peripheral locations. VA through PPLs is well predicted by the logarithm of metrics directly related with image spread (Log_Vol_PSF or equivalent) of the complete system of the eye with the lens.

Adult↗
PubMed1983

Visual acuity and its meridional variations in children aged 7-60 months.

A new operant procedure was used to assess grating acuity in children aged 7-60 months. The procedure was successful for 95% of the children sampled and had high test-retest reliability. Visual acuity for main axis (horizontal and vertical) gratings improved from 6/15 at 12 months to 6/6 at 60 months. For the 7-16 month age group, preferential-looking estimates of acuity agreed well with operant estimates. Acuity for oblique gratings was approximately 1/4 octave lower than main axis acuity throughout the age range. The results suggest that the human visual system continues to develop throughout the first 5 years of life.

Adult↗
PubMed2003

Repeatability of ETDRS visual acuity in children.

PURPOSE: To evaluate repeatability of the best corrected log minimum angle of resolution (MAR) Early-Treatment Diabetic Retinopathy Study (ETDRS) acuity in a group of 6- to 11-year old children with myopia. METHODS: Best corrected monocular visual acuity (VA) of a subset of children (n = 86) enrolled in the Correction of Myopia Evaluation Trial (COMET; mean spherical equivalent refractive error -2.35 D with no more than 1.25 D astigmatism) was measured at baseline and 1 month later with ETDRS logMAR charts. Children started with logMAR 0.4 (6/15 or 20/50) and read each letter on all subsequent lines until they missed all letters in 1 line. RESULTS: At baseline, the mean best corrected logMAR VA was 0.003 +/- 0.076 (6/6 or 20/20 +/- 3.8 letters) in the right eye and 0.008 +/- 0.059 (6/6 or 20/20 +/- 2.95 letters) in the left eye. The signed difference between VA measured at baseline and that measured at 1 month was not significantly different from zero in either eye. Repeatability was not associated with age, but a small, statistically significant association with gender was detected in the left eye, with boys approximately 2 letters more variable than girls. The kappa statistic (agreement within 1 line) was good to excellent. CONCLUSIONS: Based on the 95% limits of agreement, the criterion for a statistically significant change in VA is no more than +/-0.15 logMAR (or +/-8 letters). This value is similar to those reported for adults and indicates that logMAR VA provides a repeatable measure of acuity in children.

Child↗
PubMed2006

Long-term visual acuity and its predictors after surgery for congenital cataract: findings of the British congenital cataract study.

PURPOSE: To report long-term postoperative visual acuity in a nationally representative group of children with congenital/infantile cataract and to investigate the factors associated with poor vision. METHODS: All children aged less than 16 years in the United Kingdom who had newly diagnosed congenital/infantile cataract in a 12-month period during 1995-1996 (the British Congenital/infantile Cataract Study) were traced through their managing ophthalmologists. Outcome data were collected at least 6 years after diagnosis, by using specifically designed questionnaires. Ordinal regression analysis identified factors associated with postoperative acuity. RESULTS: Of 153 children who had surgery, complete data were available in 122 (85%). Median age at follow-up was 7 and 6.91 years, respectively, for bilateral and unilateral disease. Median age at surgery was 4.57 months in bilateral and 2.99 months in unilateral cases, with 40% and 45%, respectively, of children operated on by 3 months. Median (range) postoperative acuity was 6/18 (6/5, no perception of light) in bilateral and 6/60 (6/5, no perception of light) in unilateral disease. Poor compliance with occlusion was the factor most strongly associated with poorer acuity in both unilateral and bilateral disease: the odds of worse vision in unilateral cataract were 7.92 times greater with <50% versus 100% compliance (95% CI 1.68-37.26). In bilateral disease, odds of worse vision were reduced with each month of decreasing age at surgery (0.98, 95% CI 0.94-0.99), but increased by the presence of additional medical conditions (3.53, 95% CI 1.08-11.44) and the presence of postoperative ocular complications (2.94, 95% CI 1.38-6.51). CONCLUSIONS: These findings support a secular improvement in postoperative acuity in bilateral, and to a lesser extent, unilateral disease. Nevertheless early detection of congenital cataract through effective newborn screening and improving concordance with occlusion both remain priorities. Further improvements in outcomes in unilateral disease are necessary before parents can be advised universally that treatment will achieve a functionally useful "spare" eye.

Cataract↗
PubMed1984

[Visual acuity and traffic accidents].

In the first part of the study it was established that professional truck or bus drivers whose central photopic visual acuity in one or both eyes is less than 0.7 differ distinctly from their colleagues with fully adequate or only slightly reduced photopic vision in that they are involved in accidents more frequently (the difference is statistically significant, and in some respects highly significant). This applies in particular to accidents after 15 years' driving (known as late accidents) and accidents of the following types: priority infringements, ramming from behind, turning, and changing lanes. The first hypothesis on which the study was based, namely that accidents become more frequent as central photopic vision deteriorates, was confirmed. The second part of the investigation, which was likewise carried out with license-holders who drove professionally, produced a similar result: Drivers with considerably reduced twilight vision and/or considerably increased susceptibility to glare are more frequently involved in certain accidents at night than those who fully satisfy the minimum requirements for these visual functions. In particular, it was established that almost every fifth professional driver involved in a night-time collision with another road user (ramming, side-to-side collisions) has severely diminished twilight vision and that one out of four have increased susceptibility to glare. Thus, the second hypothesis, i.e., that the number of night-time accidents increases as twilight vision deteriorates and the driver's susceptibility to glare increases, seems fully confirmed.

Accidents, Traffic↗
PubMedDate not supplied

Preoperative visual acuity as a prognostic indicator for laser treatment of macular edema due to branch retinal vein occlusion.

BACKGROUND AND OBJECTIVE: To determine the visual outcome of laser treatments for macular edema due to branch retinal vein occlusion (BRVO) in patients with a preoperative visual acuity (VA) of 20/200 or worse compared to patients with a preoperative VA of better than 20/200. PATIENTS AND METHODS: Records of 88 patients with macular edema secondary to BRVO undergoing laser treatment from 1984 to 2003 were reviewed. Mean VA was measured before and after each treatment and after the final treatment. RESULTS: All patients received between one and five laser treatments. Preoperative VA was better than 20/200 in 56 patients (group 1) and 20/200 or worse in 32 patients (group 2). Patients in group 1 had a mean improvement of 0.48 lines and 57% had a final VA of 20/40 or better. Patients in group 2 had a mean improvement of 1.69 lines and 20% had a final VA of 20/40 or better. CONCLUSIONS: Patients with poor VA (20/200 or worse) secondary to macular edema due to BRVO responded positively to laser treatment. The level of preoperative VA can be a useful predictor of visual outcome. These patients should consider laser treatment before alternative, more aggressive approaches.

Aged↗
PubMed1990

[Effect of visual acuity degradation on stereoacuity].

53 subjects with normal binocular single vision and normal stereoacuity (SA) were performed the Titmus Stereo Test while degrading the visual acuity (VA) monocularly and binocularly with graded hazy films. The results showed that SA impairment with monocular decrement was more than with binocular symmetrical decrement at each VA level. The authors inferred that imbalance of VA between the two eyes in infants and children was harmful to the development of binocular vision, and that partial occlusion therapy would be more favorable for the binocular visual development of amblyopic children. Also, it was suggested to include SA in the criteria for cure of amblyopia.

Adolescent↗
PubMed1997

Visual acuity, erythrocyte fatty acid composition, and growth in term infants fed formulas with long chain polyunsaturated fatty acids for one year. Ross Pediatric Lipid Study.

The CNS and the retina are enriched in long chain polyunsaturated (LCP) fatty acids, specifically docosahexaenoic acid (DHA, 22:6n-3) and arachidonic acid (AA, 20:4n-6), which are present in human milk but not in most infant formulas. In the present study of 134 formula-fed and 63 breast-fed infants, we prospectively evaluated whether providing a source of DHA and AA or DHA alone in formula would increase red blood cell (RBC) phospholipid levels of these fatty acids, enhance visual function, or affect growth during the first year. Healthy term infants < 7 d old were randomized to be fed formulas containing linoleic acid (approximately 10% kcal) and alpha-linolenic acid (approximately 1% kcal) plus (1) no added LCP fatty acids (control formula), (2) DHA (0.12 wt% fatty acids) and AA (0.43 wt%) from egg yolk phospholipid (AA + DHA formula), or (3) DHA (0.2 wt%) from fish oil (DHA formula). A breast-fed group was studied concurrently and permitted formula supplementation after 3 mo. Visual acuity was measured using both the acuity card procedure and a visual evoked potential method at 2, 4, 6, 9, and 12 mo. Infants fed the control formula had 10-40% lower RBC levels of DHA and AA than infants in the breast-fed group. Infants fed the AA + DHA formula had levels of both LCP within approximately 10% of the values for infants in the breast-fed group, and infants fed the DHA formula had 25-55% higher DHA levels and 15-40% lower AA levels. There were no differences in growth or in visual function during this 12-mo feeding study.

Anthropometry↗