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Results for “Visual Acuity”

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At least 379 records · Page 21Linked to original sources

PubMed2001

[The comparison of two methods to predict the post-operative visual acuity of cataractous patients].

OBJECTIVE: To study the accurate methods to predict the post-operative visual acuity of cataractous patients with different degrees of opaque lenses. METHODS: Visual electrophysiological methods and retinometer were used to evaluate the visual function after phacoemulsification and intraocular lens implantation in 152 cases (152 eyes). The regressive analyses between the post-operative best corrected visual acuity (BCVA) and each of the following results: the pre-operative flash electroretinogram (F-ERG), flash visual evoked potentials (F-VEP) and potential visual acuity (PVA) were performed, respectively. RESULTS: More obvious linear-relationship was shown between PVA and BCVA (r = 0.654) than that between the combination of b wave's amplitude of F-ERG with wave's amplitude of F-VEP and BCVA (r = 0.528) in the patients with partial opaque lenses. Obvious linear-relationship between the combination of the F-ERG with F-VEP values and BCVA (r = 0.487) and no obvious relationship between the potential visual acuity and BCVA (r = 0.049) were shown in the patients with near complete/complete opaque lenses. CONCLUSION: Both visual electrophysiological and retinometric detection, especially the latter one, can predict the post-operative visual acuity of the patients with partial opaque lenses accurately. Visual electrophysiological detection can predict the post-operative visual acuity of cataractous patients with near complete/complete opaque lenses accurately but retinometric detection can not.

Adolescent↗

PubMedDate not supplied

Geometric ray tracing analysis of visual acuity after laser in situ keratomileusis.

PURPOSE: Using a geometric ray tracing model, we explain the increase in visual acuity observed in myopic patients after laser in situ keratomileusis (LASIK). METHODS: This study included 37 eyes of 23 patients who underwent LASIK. All patients had myopia and a spectacle-corrected visual acuity of 0.95 or worse. Clinical tests included biometry, corneal topography, pachymetry, and refraction (with and without cycloplegia). Calculations were made by tracing rays through all the refractive surfaces of the eye based on a Le Grand-type theoretical model of the whole eye. RESULTS: Comparison of spectacle-corrected visual acuity of the eye before surgery, the size of the blur circle calculated by ray tracing, and the magnification for the ocular system facilitated a numerical criterion to assess visual acuity by geometric calculation. This criterion was applied to myopic eyes that underwent LASIK, and the maximum increase in spectacle-corrected visual acuity was predicted. An actual increase in visual acuity of approximately 40% of the predicted maximum was observed in patients. CONCLUSIONS: With geometric ray tracing, it was possible not only to obtain an estimate of the visual acuity before LASIK but also to assess the value of the maximum and probable increases in visual acuity after LASIK.

Adult↗

PubMed1997

A randomised prospective comparison of operative peripheral iridectomy and Nd:YAG laser iridotomy treatment of acute angle closure glaucoma: 3 year visual acuity and intraocular pressure control outcome.

AIM: To compare visual acuity and intraocular pressure outcomes 3 years after treatment of acute angle closure glaucoma (AACG) by operative peripheral iridectomy (PI) or Nd:YAG laser iridotomy (YAG PI). METHODS: A prospective study of consecutive patients presenting to one ophthalmology department with uniocular AACG during a 2 year period. Following informed consent patients were randomised to bilateral PI or bilateral YAG PI. Three years after treatment the mean Snellen visual acuity converted to logMAR scores of the two groups was compared using the unpaired Student's t test. The number of patients with normal intraocular pressure with no further treatment in each group was compared using the chi 2 test with Yates's correction. RESULTS: 21 patients underwent bilateral PI and 27 bilateral YAG PI. Three years after treatment visual acuity was 0.30 (SD 0.28) log MAR units for PI eyes and 0.57 (0.67) logMAR units for YAG PI eyes (p = 0.08, NS). 15 (70.4%) PI eyes and 19 (71.8%) YAG PI eyes had an intraocular pressure less than 21 mm Hg with no further treatment (NS). CONCLUSIONS: There was no significant difference in visual acuity or intraocular pressure control 3 years after treatment of AACG with PI or YAG PI.

Aged↗

PubMed2004

Five-year change in visual acuity following cataract surgery in an older community: the Blue Mountains Eye Study.

AIMS: To assess the change in visual acuity following cataract surgery in the Blue Mountains Eye Study (BMES) population. Change in visual acuity was assessed by age, sex, baseline cataract type, and baseline visual acuity. METHODS: A 5-year prospective follow-up of the population-based BMES cohort, who were initially examined in 1992. After 5 years, 2335 survivors of 3654 (75.1%) baseline BMES participants were re-examined. Slit-lamp and retro-illumination lens photographs were graded for the presence of incident cataract and evidence of cataract surgery. Visual acuity was measured using a logMAR chart, read at 2.4 m. The main outcome measure was change in the number of logMAR letters correctly identified by eyes that underwent cataract surgery during the 5-year follow-up period. RESULTS: In a multiple linear regression model, age (P<0.0001) and early age-related maculopathy (ARM) at baseline (P<0.0001) were found to affect adversely the postoperative visual acuity following the cataract surgery. As expected, eyes with any baseline cataract showed the greatest improvement in visual acuity after cataract surgery (right eyes: mean +/- s.e. change of 3.75 +/- 1.34 letters; left eyes: mean change +/- s.e. of 6.7 +/- 0.99 letters). There was also a statistically significant improvement in vision after cataract surgery in eyes with no significant lens opacity graded as present at baseline (right eyes: mean +/- s.e. change of 3.78 +/- 1.85 letters; left eyes: mean change +/- s.e. of 2.68 +/- 1.33 letters). CONCLUSIONS: Age and baseline cataract or ARM status, and baseline visual acuity were determinants of the postoperative visual outcome in older persons who underwent cataract surgery in this community.

Age Factors↗

PubMed2003

Responsiveness of the National Eye Institute Visual Function Questionnaire to changes in visual acuity: findings in patients with subfoveal choroidal neovascularization--SST Report No. 1.

BACKGROUND: The National Eye Institute Visual Function Questionnaire (NEI-VFQ) measures vision-targeted quality of life, but it is unclear whether it is sensitive to changes within individuals over time. OBJECTIVE: To determine the responsiveness of the NEI-VFQ to "within-individual" changes in visual acuity in patients who had subfoveal choroidal neovascularization in at least one eye secondary to age-related macular degeneration, ocular histoplasmosis syndrome, or idiopathic causes, and who participated in randomized trials of submacular surgery. METHODS: Trained telephone interviewers administered the NEI-VFQ as part of annual follow-up data collection for pilot trials and larger clinical trials of submacular surgery. Best-corrected visual acuity was measured by local vision examiners at 12 months after enrollment and, typically, by central "traveling" vision examiners at 24 months after enrollment. Changes in visual acuity and NEI-VFQ scores from 12 to 24 months were analyzed using linear regression methods. RESULTS: Two-hundred eighteen patients had both interviews and visual acuity measurements at 12 and 24 months after enrollment. Changes in the overall NEI-VFQ score and in 9 of the subscales (near activities, dependency, driving, role difficulties, distance activities, mental health, general vision, peripheral vision, and social functioning) were related to changes in visual acuity of the better-seeing eye based on linear regression analysis (P<.05). In our analysis, a 3-line decrease in the visual acuity of the better-seeing eye was associated with 3.6- to 16.2-point decreases in the overall NEI-VFQ score and 9 subscale scores. CONCLUSIONS: Most of the NEI-VFQ subscales were responsive to changes in the visual acuity of the better-seeing eye over a 12-month interval in this patient population. Thus, the NEI-VFQ can be used to measure change in vision-targeted quality of life over time to augment clinical measurements of visual acuity.

Adult↗

PubMed1992

[Multifocal and monofocal implant. Comparative functional results (contrast sensitivity and dynamic visual acuity)].

The functional results (contrast sensitivity and dynamic visual acuity) of 19 multifocal (3 M design) and 14 monofocal intraocular (IOL) were compared. Best corrected visual acuity was > or = 8/10 P 2. Major differences of functional performance in favour of monofocal IOL's were found under standard conditions of vision (low contrast and illumination levels). Dynamic visual acuity allowed accurate evaluation of the difference of performance between these two models of implant. The indications for multifocal IOLs were reconsidered in the light of these results.

Aged↗

PubMed1992

Studies on contrast visual acuities in normal, cataractous and pseudophakic eyes.

Contrast sensitivity and glare sensitivity are often abnormal in cataract patients. However, despite significant subjective complains, relatively good visual acuities are obtained with high-contrast optotypes. Using Variable Contrast Visual Acuity Charts with contrast levels of 90, 15, and 2.5% and reverse polarity of 90% contrast, contrast visual acuities were measured in 24 normal subjects (40 eyes) (Landolt visual acuity > or = 1.0); 28 cataract patients (40 eyes) (Landolt visual acuity > or = 0.6); and 75 patients (100 eyes) [best-corrected Landolt visual acuity > or = 0.8 after intraocular lens (IOL) implantation]. The cataract group experienced the greatest decrease of contrast visual acuity when the high-contrast chart (chart 1) measurements were compared with the 15% (0.71 vs 0.52-0.64 octave) and the 2.5% contrast charts (1.75 vs 1.21-1.48 octaves), followed by the IOL group, and the normal subjects. In the cataract group, 23/40 eyes (57.5%) showed better contrast visual acuity with chart 4 than chart 1. Although much less in frequency, 28/100 (28%) eyes with IOLs also showed better contrast acuity measured with chart 4 than with chart 1. In addition to high-contrast optotypes, acuity measurements using intermediate- to low-contrast optotypes, combined with the reverse polarity chart, seem effective to analyze visual disabilities caused by early cataract. The pattern of the contrast acuity profile of the IOL patients was comparable to normal subjects, but the glare effect still existed after IOL implantation, though to a lesser degree than in cataractous eyes.

Adult↗

PubMed1997

Comparison of visual acuity measured with Allen figures and Snellen letters using the B-VAT II monitor.

OBJECTIVE: Allen figure optotypes commonly are used to measure visual acuity in young children. Children with normal acuity measured with Allen figures sometimes are found to have unsuspected amblyopia that is detected when they are tested with Snellen letters. The correlation between visual acuities measured with these two optotype charts has not been well studied. The authors compared visual acuities measured with Allen figure and Snellen letter optotypes using the Mentor B-VAT II monitor. DESIGN: The study design was a nonrandomized, comparative clinical trial. PARTICIPANTS: The study was composed of 12 adult subjects. INTERVENTION: Visual acuities were measured using both Allen figure and Snellen letter optotypes using the B-VAT II monitor. The images were progressively blurred using plus lenses. MAIN OUTCOME MEASURES: Visual acuity was measured. RESULTS: At visual acuity levels of 20/60 or better, Allen figure testing averaged 1.5 lines better than Snellen letter testing; between 20/70 and 20/200 visual acuities, the difference was 2.5 lines. CONCLUSIONS: Allen figure testing with the B-VAT II monitor overestimates visual acuity compared with testing with Snellen letters. This appears to result primarily from the construction of the optotypes. This discrepancy should be considered when visual acuity is measured in young children.

Adult↗

PubMed2005

The application of a new continuous functional visual acuity measurement system in dry eye syndromes.

PURPOSE: To evaluate the efficacy of a new continuous functional visual acuity measurement (FVAM) system for the assessment of dry eye patients. DESIGN: Prospective comparative study. METHODS: Monocular recognition acuity measured continuously by the FVAM system during a 30-second blink-free period was defined as functional visual acuity (FVA). Examinations using the FVAM system were conducted in 35 eyes of 20 healthy controls and 19 eyes of 13 dry eye patients. Tear function examinations including the Schirmer test, tear film break-up time, and fluorescein and Rose Bengal staining were performed in all subjects. Functional visual acuity and tear functions were also examined before and after insertion of punctum plugs in dry eye patients. Functional visual acuity results at 10, 20, and 30 seconds were compared. RESULTS: Functional visual acuity in dry eyes were significantly lower than control subjects at all time points (P < .05). Functional visual acuity after punctum plugs insertion improved significantly at all time points (P < .05). CONCLUSIONS: FVAM system seemed not only to be an effective tool in the assessment of dynamic visual acuity changes in dry eye and normal subjects but in evaluating the outcome of management of dry eye disease by punctum plugs.

Adult↗

PubMed1986

Ultraviolet effects on visual acuity in pseudophakia.

Two experiments investigated visual acuity deficits in the presence of ultraviolet (UV) light after implantation of an acrylic intraocular lens (IOL). In Experiment 1, six pseudophakes exhibited a statistically significant acuity decrement of 0.5 min arc or about one line on an eye chart illuminated by light having an UV component. In Experiment 2, the vernier acuity of six pseudophakic observers decreased by 0.6 min arc, but the vernier acuity of six phakic observers, with crystalline lenses intact, was not affected significantly by UV illumination. Both experiments provide evidence that UV light decreases pseudophakic visual acuity, perhaps by chromatic aberration. These results suggest that including UV filters in IOL's could permit pseudophakic observers to use their vision more effectively.

Aged↗

PubMedDate not supplied

Does postoperative near visual acuity predict macular hole closure?

To determine whether prone postoperative near visual acuity following macular hole surgery can be used as a reliable indicator of successful hole closure, data from 21 patients undergoing macular hole surgery were collected. Seventeen of the 18 patients with hole closure and all 3 patients with persistent macular holes had a Rosenbaum acuity better than preoperative visual acuity, yielding 94% sensitivity, 0% specificity, 85% positive predictive value, and 0% negative predictive value. Fourteen of the 18 patients with macular hole closure and all 3 patients with persistent macular holes had a Rosenbaum acuity better than 20/40, yielding 78% sensitivity, 0% specificity, 82% positive predictive value, and 0% negative predictive value. Although postoperative near visual acuity can predict macular hole closure with 94% sensitivity, the test is not clinically useful to predict hole closure because of the high surgical success rate of macular hole surgery. The test could be useful in encouraging patients to maintain head prone positioning and alleviate patient anxiety.

Aged↗

PubMed1992

Visual acuity correlates with severity of retinopathy of prematurity in untreated infants weighing 750 g or less at birth.

Visual acuity was assessed in 72 patients who weighed 750 g or less at birth, had intact visual pathways as confirmed with computed tomography or magnetic resonance imaging, and had at least one eye evaluated for cicatricial sequelae after active, untreated retinopathy of prematurity without macular detachment (stage 4a or better). Visual acuities were obtained for 137 untreated, sighted eyes. Severity parameters for retinopathy of prematurity (stage of retinopathy of prematurity, refraction [in spherical equivalents], macular ectopia [in disc diameters], and vessel traction [in 30 degrees sectors]) was were significant predictors of visual acuity (P less than .0001) based on results of linear regression and stepwise regression analyses; however, parameters of retinal immaturity (birth weight, gestational age, and zone of retinopathy of prematurity) were not significant predictors of visual acuity. Visual acuity of the study eyes was good (median, 20/30; geometric mean, 20/33.58), with no statistical differences between eyes evaluated on last examination with linear Allen figures and those evaluated with linear Snellen test types.

Child, Preschool↗

PubMed1992

Near visual acuity: a simple measure of practical significance in insulin-treated diabetic patients.

The value of measuring near visual acuity as a predictor of loss of independence in administering insulin and monitoring blood or urine glucose has been assessed in 110 insulin-treated diabetic patients. Near visual acuity was simple to measure in the clinic setting, and correlated well with 6 m acuity. Fourteen patients depended on an assistant either to draw up the correct dose of insulin (n = 12), inject the insulin (n = 7) or to monitor blood or urine glucose (n = 12). Of these 14 patients only one, who was demented, had near visual acuity better than N.12. Two other patients had near visual acuity N.12 or worse and yet were independent of help. One had severe visual impairment and used a pen-injector and a meter with speech synthesizer, and the other had near visual acuity of N.12. Impairment of near visual acuity to N.12 or worse is associated with loss of independence in insulin-treated diabetes. Measurement of near visual acuity could be useful in predicting independence of insulin-treated patients.

Blood Glucose Self-Monitoring↗

PubMed1993

[Visual acuity testing of three- and four-year old nursery school and kindergarten children].

Visual acuity testing was conducted on 1,531 children in nursery schools and kindergartens in Chita district, for the purpose of determining the rate of successfully performing the test, as well as the visual acuity of those shown to be normal by various ophthalmologic examinations. The rate of successful performance of the visual acuity test increased monthly with increasing age, with maximum changes seen at 4-5 months after the third birthday. The rate of successful performance of the test at the third birthday was 73%, progressively increasing up to 95% in the successive 6 months. The rate at the fourth birthday became almost 100%. Average of visual acuity of 3.0-year old children was 0.55, and for 3.5-year olds was 0.82. The average visual acuity reached 0.88 at 4.0 years of age, and at 4.5 years of age became 0.97. In view of the results obtained, it is concluded that children who could not successfully perform a visual acuity test at 3.0-years of age should be tested again at 3.5-years of age. Preferably the vision screening should be performed during the period between 3.5- and 4.0-years of age, for reliability and efficiency. Accordingly, the screening standards should also be changed with consideration given to visual development of children of this age.

Child↗

PubMed2005

Visual acuity development after the implantation of unilateral intraocular lenses in infants and young children.

PURPOSE: Intraocular lenses (IOLs) are now being implanted in infants and children with unilateral cataracts. However, there are no prospective data on the development of visual acuity after implantation. The aim of the present study was to prospectively assess the development of acuity in infants and preschool children who received IOLs or aphakic contacts lenses (CLs) after the extraction of a unilateral cataract. METHODS: Visual acuity was assessed using Teller Acuity Cards and/or crowded HOTV tests at target ages of 6 months, 1, 2, 3, and 4 years. RESULTS: Infants who received a primary IOL after extraction of dense congenital unilateral cataract (n = 5) showed improvement from an initially low mean visual acuity of 20/170 at 6 months to 20/85 at 12 months and 20/54 at 4 years. Visual acuity in the IOL group was similar to that of children who had good-to-excellent compliance with CL wear (n = 36; 4-year visual acuity 20/50) and better than that of children who had moderate-to-poor compliance (n = 11; 4-year visual acuity 20/135). Children who received IOLs after extraction of developmental unilateral cataracts by 6 months (n = 4; 4-year visual acuity 20/55) had visual acuity development similar to those treated with CLs (n = 5; 4-year visual acuity 20/55). Children who received IOLs after extraction of developmental unilateral cataracts after 1 year of age (n = 18) had better visual acuity than children those treated with CLs (n = 4) at 4 years of age (20/40 vs. 20/135). CONCLUSION: IOLs and aphakic CLs support similar visual acuity development after surgery for a unilateral cataract. IOLs may support better visual acuity development when compliance with CL wear is moderate to poor or when a cataract is extracted after 1 year of age.

Aphakia, Postcataract↗

PubMed1992

Contrast visual acuities in cataract patients. I. Comparison with normal subjects.

Contrast sensitivity and glare sensitivity are often abnormal in cataract patients. However, despite significant subjective complaints, relatively good visual acuities often are obtained with high-contrast optotypes. Using Variable-Contrast Visual Acuity Charts (VCVAC), we measured visual acuities of 40 eyes of 24 normal subjects (visual acuity greater than or equal to 1.0) aged 41 to 72 years, and 40 eyes of 28 cataract patients (visual acuity greater than or equal to 0.6) aged 44 to 81 years. The VCVAC consists of 4 different charts (1-4). The contrast is 90% in charts 1 and 4, 15% in chart 2 and 2.5% in chart 3. Chart 4 is the reverse polarity of chart 1. The decrease of visual acuity compared with the high-contrast chart (chart 1) was larger in the cataract group with both in the 15% contrast (0.52 vs. 0.71 octave) and the 2.5% contrast (1.21 vs. 1.75 octaves). In cataract group, 23/40 eyes (57.5%) showed better visual acuity with chart 4 than that of chart 1. In addition to high-contrast optotypes, acuity measurements using intermediate- to low-contrast optotypes, combined with the reverse polarity chart, seem effective in analyzing the visual disabilities caused by early cataract.

Adult↗

PubMed1982

New visual acuity charts for clinical research.

Three new visual acuity charts facilitate quantitative use of visual acuity test results. The charts have high-contrast lettering on washable white polystyrene. Each line has five Sloan letters; the lines are of equal difficulty and there is a geometric progression in letter size from line to line. This provides a similar task for each line on the chart with the letter size being the only variable. Charts with different letter sequences are used for testing right and left eyes.

Humans↗

PubMed1996

Clinical vision characteristics of the congenital achromatopsias. I. Visual acuity, refractive error, and binocular status.

Visual acuity, refractive error, and binocular status were determined in 43 autosomal recessive (AR) and 15 X-linked (XL) congenital achromats. The achromats were classified by color matching and spectral sensitivity data. Large interindividual variation in refractive error and visual acuity was present within each achromat group (complete AR, incomplete AR, and XL). However, the number of individuals with significant interocular acuity differences is very small. Most XLs are myopic; ARs show a wide range of refractive error from high myopia to high hyperopia. Acuity of the AR and XL groups was very similar. With-the-rule astigmatism of large amount is very common in achromats, particularly ARs. There is a close association between strabismus and interocular acuity differences in the ARs, with the fixating eye having better than average acuity. The large overlap of acuity and refractive error of XL and AR achromats suggests that these measures are less useful for differential diagnosis than generally indicated by the clinical literature.

Adolescent↗