Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Visual Acuity”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources
PubMed1987

Potential acuity meter for predicting postoperative visual acuity in penetrating keratoplasty. A new method using a hard contact lens.

An irregular corneal surface degrades the optical transmission and limits the effectiveness of the potential acuity meter (PAM) in predicting post-keratoplasty visual acuity. The authors investigated the efficacy of using a temporarily placed hard contact lens to neutralize surface irregularities in conjunction with the PAM in predicting post-keratoplasty visual acuity. A prospective evaluation was performed on 40 keratoplasty patients with a mean follow-up of 10.4 months. Of 27 patients with corneas clear enough to permit them to read letters on the PAM chart, 17 (63%) had very accurately predicted visual acuities by this new method, compared to only eight patients (30%) with the PAM alone. Three patients had predicted visions better than final vision, but this was due to a concurrent cataract in two cases and chronic cystoid macular edema (CME) in the third case. This study indicates that temporarily placing a hard contact lens for use with the PAM can increase its accuracy in predicting final visual acuity after penetrating keratoplasty.

Adult↗
PubMed2006

[Some remarks on the precision of visual acuity measurements].

BACKGROUND: Visual acuity measurements are used to determine the course of diseases, treatment outcomes, consequences of accidents, and the occupational ability of a patient. The fact, that visual acuity depends both on visual function as well as on the circumstances of examination, is often understood more intuitively than explicitly. Precision and accuracy of visual acuity measurements must be kept in mind, and occasionally need to be quantified and statistically evaluated, to avoid clinical errors. METHODS: Factors influencing acuity measurements are analyzed. Using appropriate examples the precision of acuity measurements is evaluated and quantified with standard vision test charts and threshold or staircase procedures. Limits of confidence and limits of tolerance are described for the statistical evaluation of consecutive visual acuity measurements. RESULTS AND CONCLUSIONS: The statistical evaluation of standard procedures is relatively time consuming, as 3 to 4 standardized measurements are needed on first examination and on follow-up. Threshold and staircase methods, however provide more feasible data, due to the examination technique. All evaluation procedures described here, can only be applied with logMAR acuity readings.

Confidence Intervals↗
PubMed2005

[Subjective decrease of visual acuity after photodynamic therapy: documentation by optical coherence tomography and its correlation with visual acuity].

CASE REPORT: A 68-year-old patient complained of decreased visual acuity (VA) two days after photodynamic therapy (PDT) had been performed. VA decreased from the pre-operative value of 0.4 to 0.1 on the second postoperative day. With additional + 1.75 diopters, VA was 0.32. Optical coherence tomography (OCT) disclosed a subneuroretinal fluid accumulation causing a serous retinal detachment 600 microm in height. One week postoperatively, neither decreased vision nor retinal elevation were noted. DISCUSSION: The temporary subjective decreased VA could be predominantly reduced by adequate refraction. OCT and VA measurements excluded ischemia of the neuroretina or the choroid as a causative factor.

Aged↗
PubMed2003

Wavelength dependence of visual acuity in goldfish.

Visual acuity was measured in a two-choice training experiment with food reward. Four goldfish were trained to select a homogeneously illuminated testfield when a high-contrast grating (transparency) was shown for comparison at the second testfield. Measurements were performed for white and monochromatic testfield illuminations in the light adapted state. Fourteen wavelengths between 404 nm and 683 nm were tested. For each wavelength (and white light) the testfield intensity was determined for which spatial resolution was highest. Between 446 nm and 683 nm maximal values of 2.0 cycles/deg (corresponding to a visual acuity of 15' of arc) were found. At 404 nm and in the ultraviolet resolution was lower (0.6 and approximately 0.25-0.35 cycles/deg, respectively). Cone and small ganglion cell densities may equally account for visual acuity. The action spectrum of maximal visual acuity is very similar to the spectral sensitivity function representing recognition of "colour". Measurements under reduced room illumination and after treatment with Ethambutol further indicate that the detection of high contrast gratings is processed by the same "channel" as colour vision. A similar separate and parallel processing of "colour" and "form" on the one hand, and "brightness" and "motion" on the other hand was found in humans.

Animals↗
PubMed2005

Visual acuity and perimetry as measures of visual function in diabetic macular oedema.

AIMS/HYPOTHESIS: We examined to what extent visual acuity and perimetric sensitivity as measures of central and paracentral visual function would be useful for evaluating the presence and severity of diabetic macular oedema. MATERIALS AND METHODS: We evaluated 59 eyes of 59 diabetic patients by identifying the presence (n=20) or absence (n=39) of macular oedema on stereo fundus photographs. The area of oedema and its distance to the centre of the macula were measured. Ischaemic macular damage was quantified by measuring the foveal avascular zone and adjacent perifoveolar intercapillary areas on fluorescein angiograms. Visual function was assessed by visual acuity charts and by short-wavelength perimetry and standard white-on-white perimetry of the central 10 degrees field. RESULTS: Visual acuity did not differ between eyes with and without macular oedema. In eyes with oedema, visual acuity was correlated to the distance of the oedema from the centre of the macula (log of minimum angle of resolution {LogMar} score decreased by 0.15/mm; p=0.006) and to the thickness of the retina when the centre was affected (LogMar score decreased by 0.003/mum of thickness; p=0.0002). Multivariate analyses confirmed the results (R (2)=0.46 and 0.77, respectively). Short-wavelength perimetry sensitivity was more depressed in eyes with oedema (p=0.033) but was not significantly associated with the presence of oedema after correction for macular ischaemic damage. There was no correlation between these field defects and the severity of oedema. CONCLUSIONS/INTERPRETATION: Visual acuity was a useful measure of visual function in diabetic macular oedema involving the centre. Visual field defects were more common in eyes with macular oedema but reflected ischaemic damage of the macula rather than macular oedema itself.

Adult↗
PubMed1991

Potential acuity meter for predicting visual acuity after Nd:YAG posterior capsulotomy.

The potential acuity meter (PAM) was designed to evaluate visual acuity in 22 eyes that required secondary capsulotomies. The PAM prediction was within one line in 13 eyes (59%) and within two lines in 17 eyes (77%) and had an 18% rate of falsely bad prediction (more than two lines) and 5% rate of falsely good prediction for YAG capsulotomy. In aphakic patients, however, further study is necessary.

Aged↗
PubMed1987

Visual acuity prediction using the visual evoked response.

A technique is described for predicting visual acuity in adult humans by using the visually evoked response (VER). This involves using a pattern-reversal checkerboard with a small check size (5.5. min arc) as the stimulus, and measuring the peak-to-trough amplitude of the VER wave arising from it. The technique is therefore both rapid and convenient. The pattern-reversal rate was varied in order to assess the influence of the temporal modulation on the VER waves. The results suggest that a rapid pattern reversal rate produces a VER which displays a reduced association with spatial processing.

Adult↗
PubMed1987

Brightness acuity test and outdoor visual acuity in cataract patients.

The disparity between functional outdoor vision and the acuity measured in the standard refracting lane is well known among clinicians. A simple device, the brightness acuity tester (B.A.T.), was developed to predict a patient's functional outdoor acuity. The B.A.T. has an illuminated hemispheric bowl, 60 mm in diameter, with a 12-mm aperture. Fourteen normals and 50 patients with cataracts were tested using the B.A.T. and then tested outside in bright sunlight. The B.A.T. correlated extremely well (r = +0.84, P less than .0001) with the acuities measured outside. There was no decrease in visual acuity in the 14 normal patients, but there was a one to ten line decrease in vision among the cataract patients. Upon retesting, the B.A.T. scores did not vary, while outside testing scores did change due to variable outdoor ambient light levels on sunny days. The B.A.T. is a simple, repeatable, useful test for predicting functional outdoor acuity.

Cataract↗
PubMedDate not supplied

Assessment of visual acuity in toddlers.

Visual acuity in children 15 to 35 months of age is particularly difficult to measure. Children in this age range become bored with methods used for assessment of infants, but they are often not capable of responding to the tests used with older children and adults. Partially because of these difficulties, there is no widely preferred standard test of visual acuity for the 15 to 35 month age range. Instead, a variety of behavioral techniques have been used, with varying degrees of success. These techniques will be described and evaluated with regard to adequacy of norms, percent testable rates, test times, accuracy and similarity to adult standards of visual acuity assessment. Practical suggestions regarding the use of existing techniques and the development of new visual acuity assessment techniques for 15- to 35-month-olds will be given.

Child Behavior↗
PubMed1994

Use of the potential acuity meter and laser interferometer to predict visual acuity after macular hole surgery.

PURPOSE: As reported anatomic success rates for macular hole surgery increase, a method of accurately predicting postoperative visual acuity has increased clinical utility. METHODS: A series of 18 patients undergoing vitrectomy for idiopathic macular holes was evaluated prospectively for best refracted preoperative visual acuity, potential acuity meter (PAM) reading, and laser interferometer (LI) reading. Best refracted visual acuity after surgery was recorded and analyzed to assess the predictive value of the PAM and LI readings. RESULTS: The LI correctly predicted the final visual result in 6 of the 10 patients who achieved a final visual acuity of 20/50 or better (P = < 0.011). The PAM did not accurately predict postoperative visual acuity for any of the eyes with a final visual acuity of 20/50 or better. Both correctly predicted outcome in the 7 patients with final visual acuity worse than 20/50. The LI prediction was within 2 lines of final visual acuity in 12 (70%) of 17 anatomically successful cases, and the PAM was within 2 lines of final visual acuity in 11 (64%) of 17 cases. CONCLUSION: Both the LI and PAM were modestly accurate in predicting final visual acuity after macular hole surgery, but the LI was more accurate in predicting a visual acuity of 20/50 or better.

Aged↗