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[A new apparatus for objective visual acuity evaluation].

The Catford Visual Acuity Apparatus is supposed to offer an easy and time-saving possibility for an objective determination of the visual acuity. No useful results were obtained from a survey, including 27 patients of varius age-group, which were examined at the recommended distance. Furthermore, because the examination becomes affected by other negative components, that come into perspective at the optimal distance of examination of 2 meters, this apparatus cannot be recommended for the use of an oculist in his practice.

Adolescent↗

[Prediction of postoperative visual acuity in retinal detachment with macular involvement].

We used laser interferometry (LI) and a potential acuity meter (PAM) to predict visual acuity after surgery for patients with rhegmatogenous retinal detachment with macular involvement. Thirty one eyes of 31 patients with retinal detachment were treated with scleral buckling procedures. Postoperative visual acuity was correlated with preoperative measurements of the LI and PAM, preoperative visual acuity by Landort's ring, and the estimated duration of macular detachment. The correlation between the duration of macular detachment and the postoperative visual acuity was not good (r = 0.55, p < 0.01). Although the preoperative visual acuity showed a relatively good correlation with postoperative visual acuity (r = 0.62, p < 0.01), the results of the LI and PAM provided a better correlation (LI; r = 0.73, PAM; r = 0.71). Our results suggest that the LI and PAM are useful to predict the visual acuity after retinal reattachment in patients with preoperative macular detachment.

Humans↗

Maturation of the visual evoked response and its correlation with visual acuity in preterm infants.

Visual evoked responses (VERs) were elicited in 70 infants with postmenstrual ages between 30 and 39 weeks. On the basis of neurological and ultrasound examinations, 30 of the infants were classed as neurologically normal and 40 as abnormal: 26 of the latter had periventricular haemorrhage. Initially the VER consisted of a negative deflection only, and the appearance of a positive wave immediately preceding the negative deflection was taken to indicate maturation of the VER. Maturation was significantly delayed in the neurologically abnormal infants, and the delay was related to the degree of neurological insult. The visual acuity of 32 infants was estimated within seven days of the VER recording. There was a correlation of 79 per cent between the VER and the data for visual acuity.

Birth Weight↗

Visual acuity measurements by swept spatial frequency visual-evoked-cortical potentials (VECPs): clinical application in children with various visual disorders.

Previous studies have indicated that visual acuities of normal infants can be estimated with good accuracy using swept spatial frequency visual-evoked-potentials (VECPs). In this report we describe acuity measurements obtained with this technique from 304 examinations performed on 135 children having various visual disorders. When possible, two or more different stimulation frequencies (8, 12, 15 or 24 contrast reversals/sec) were used in each patient, and three to eight sweep VECPs were obtained from each patient under each simulation and recording condition. High correlation coefficients (0.94 - 0.96) between the acuity estimated on each patient from either the single sweep giving the best visual acuity (BSS) or from vector averages (VeA) of the EEG data obtained from several sweeps confirmed previous findings in normal infants. We also found high correlation coefficients among BSS recorded at different temporal frequencies (0.79-0.97) and among comparisons of BSS or VeA acuity to optotype visual acuity (0.6-0.89). Children with clinically undetectable optokinetic responses showed lower visual acuity estimated by BSS than those who demonstrated optokinetic nystagmus. We conclude that the sweep VECP is a valid method, giving estimates of acuity which correlate well with optotype acuity and correspond well to other clinical findings, and that it can be useful in the clinical management of nonverbal patients.

Child↗

Subfoveal choroidal neovascular membranes in age-related macular degeneration. Visual prognosis in eyes with relatively good initial visual acuity.

We determined the visual prognosis of 94 eyes in 92 patients having age-related macular degeneration, a discrete choroidal neovascular membrane directly under the center of the foveal avascular zone (subfoveal), and an initial visual acuity of 20/100 or better. Of the patients who were reexamined 24 months following their initial presentation, 77% had lost at least four lines of vision and 64% had lost at least six lines. Estimation of visual loss using a conservative assessment procedure showed four-line visual loss in 65% of the patients and six-line loss in 50%. In general, the better the visual acuity at the initial examination, the more likely the patient was to have a smaller choroidal neovascular membrane. These results suggest that it may be reasonable to consider a randomized clinical trial of laser photocoagulation for this group of patients with a relatively poor visual prognosis.

Age Factors↗

Use of best and final visual acuity outcomes in ophthalmological research.

OBJECTIVE: To evaluate how often visual acuity outcomes are reported in the ophthalmological literature as best or final outcomes, despite potential bias with this type of analysis, as compared with interval outcomes, when a specific condition may continue to cause gain or loss of visual acuity beyond the time that the best or final outcome is determined. METHODS: Each article published in the 3 most frequently cited comprehensive clinical ophthalmological journals in the United States from January through December 2000 was reviewed. Clinical studies were identified in which visual acuity was used as an outcome measure. Visual acuity outcomes were examined throughout the articles and classified as follows: best visual acuity, defined as an outcome at any time during follow-up; final visual acuity, defined as an outcome at last follow-up; and interval visual acuity, defined as an outcome at specified follow-up times. A few factors that might be associated with the different types of outcome were evaluated. Reproducibility of the categorization between 2 ophthalmologists evaluating the articles was determined by using the kappa statistic. RESULTS: A total of 527 clinical studies met the criteria. Among these, authors of 195 reported visual acuity as an outcome measure. Authors of 1 article (0.5%) reported only best visual acuity, authors of 6 (3%) reported both best and final visual acuity, authors of 113 (58%) reported only final visual acuity, and authors of 73 (37%) reported interval visual acuity outcomes. Reproducibility of these categorizations between 2 ophthalmologists was considered excellent, as compared with chance alone (kappa = 0.84). Authors of only 2 of the 120 articles that used either best or final visual acuity outcomes discussed the limitations or potential bias of reporting outcomes in this way. Randomized trials and other prospective study designs more often were associated with interval outcomes than were nonrandomized and retrospective studies. CONCLUSIONS: Despite potential bias with use of best or final visual acuity outcomes, these end points alone were used in most studies published during 2000 in the 3 most commonly cited journals. Authors of clinical studies should consider avoiding use of best or final visual acuity outcomes whenever possible to minimize possible data misinterpretation. If best or final outcomes are used, authors should consider discussing the limitations of these methods and their potential effect on the interpretation of results.

Bias↗

Early uncorrected visual acuity as a measurement of the visual outcomes of contemporary cataract surgery.

PURPOSE: To determine the uncorrected visual acuity (UCVA) on the first postoperative day and the fifth week after routine slow-motion phacoemulsification with posterior chamber intraocular lens (IOL) implantation. SETTING: Cincinnati Eye Institute, Cincinnati, Ohio, USA. METHODS: This retrospective chart review performed by 3 research fellows analyzed the UCVA 1 day and 5 weeks postoperatively in 100 consecutive best-case scenario eyes of 99 patients who had routine slow-motion phacoemulsification with implantation of an AcrySof single-piece IOL (Alcon). Reasons for UCVAs worse than 20/40 were sought. The stability of the visual result was analyzed. RESULTS: The UCVA was 20/40 or better in 98% of eyes at 1 day. Ninety-seven percent had a UCVA of at least 20/40 by 5 weeks, confirming stability of acuity. The percentage of patients with a UCVA of 20/20 or 20/25 increased from 49% at 1 day to 77% at 5 weeks. CONCLUSIONS: The UCVA 1 day after slow-motion phacoemulsification was 20/40 or better in 98% of eyes and remained stable to the last measurement at 5 weeks. Early UCVA can serve as a more sensitive measurement than best corrected visual acuity for assessing new surgical technologies and techniques.

Acrylic Resins↗

The ABCs of visual acuity assessment.

An accurate visual acuity assessment is an important part of the ophthalmic examination. Each patient needs his or her vision assessed whether an adult, a baby, or a child. The purpose of this article is to review some of the testing methods used to assess vision in the less than 20/200 adult, the preverbal infant, and the uncooperative or timid child. Several "pearls and pitfalls" will be mentioned to help you obtain the best visual acuity assessment on all types of patients.

Adult↗

Collaborative ocular melanoma study (COMS) randomized trial of I-125 brachytherapy for medium choroidal melanoma. I. Visual acuity after 3 years COMS report no. 16.

OBJECTIVE: To report visual acuity during the first three years after iodine 125 (I(125)) brachytherapy for medium-sized choroidal melanoma and to identify important baseline and treatment factors associated with posttreatment visual acuity in a group of patients who were treated and observed prospectively as part of a large, randomized clinical trial. DESIGN: Observational case series within a randomized, multicenter study. PARTICIPANTS: Patients enrolled in the Collaborative Ocular Melanoma Study randomized trial of I(125) brachytherapy versus enucleation had choroidal melanoma of at least 2.5 mm but no more than 10.0 mm in apical height, and no more than 16.0 mm in largest basal dimension. One thousand three hundred seventeen patients enrolled from February 1987 through July 1998; 657 patients were assigned to I(125) brachytherapy. Visual acuity data for 623 patients who received I(125) brachytherapy as randomly assigned and who have been observed for at least 1 year were analyzed for this report. METHODS: Under study protocol, an ophthalmic evaluation, including best-corrected visual acuity measurement of each eye, was performed at baseline, every 6 months thereafter for 5 years, and once yearly thereafter. Two poor vision outcomes, visual acuity of 20/200 or worse that was confirmed at the next follow-up examination and loss of six lines or more of visual acuity from baseline that was confirmed at the next follow-up examination, were analyzed to identify baseline and treatment characteristics that were associated with posttreatment visual acuity. RESULTS: At baseline, median visual acuity in the eye with choroidal melanoma was 20/32, with 70% of eyes having 20/40 or better and 10% of eyes having 20/200 or worse visual acuity. Three years after I(125) brachytherapy, median visual acuity was 20/125, with 34% having 20/40 or better and 45% having 20/200 or worse visual acuity, including eyes that were enucleated within 3 years of treatment. Life-table estimates of percentages of patients who lost six or more lines of visual acuity from baseline, a quadrupling of the minimum angle of resolution, with this finding confirmed at the next 6-month follow-up examination, were 18% by 1 year, 34% by 2 years, and 49% by 3 years after treatment. Life-table estimates of percentages of patients with baseline visual acuity better than 20/200 whose visual acuity decreased to 20/200 or worse, confirmed at the next follow-up examination, were 17% by 1 year, 33% by 2 years, and 43% by 3 years after treatment. As soon as a poor vision outcome was observed, improvement of visual acuity to a level that no longer met the definition for a poor vision outcome was rare. Greater baseline tumor apical height and shorter distance between the tumor and the foveal avascular zone (FAZ) were the factors most strongly associated with loss of six or more lines of visual acuity after treatment. These two factors and baseline visual acuity also were strongly associated with visual acuity 20/200 or worse after treatment. Patient history of diabetes, presence of tumor-associated retinal detachment, and tumors that were not dome shaped also were associated with greater risk for both of the poor vision outcomes. CONCLUSIONS: Forty-three percent to 49% of treated eyes had substantial impairment in visual acuity by 3 years after I(125) brachytherapy, defined as a loss of six or more lines of visual acuity from the pretreatment level (49% of eyes) or visual acuity of 20/200 or worse (43% of eyes) that was confirmed at the next 6-month examination. Patients with a history of diabetes and patients whose eyes had thicker tumors, tumors close to or beneath the FAZ, tumor-associated retinal detachment, or tumors that were not dome shaped were those most likely to have a poor visual acuity outcome within 3 years after I(125) brachytherapy.

Adult↗

Comparison of the HOTV and Lea symbols visual acuity tests in patients with amblyopia.

PURPOSE: To determine whether the Lea symbols visual acuity test, compared with the HOTV visual acuity test, overestimates visual acuity in patients with amblyopia. PATIENTS AND METHODS: Fifty-nine patients with amblyopia or a history of amblyopia treatment had visual acuity measurements in both eyes with the HOTV and Lea symbols tests. Crowding bars, separated by a width of 1 optotype, and the original pilot-testing protocol in the Amblyopia Treatment Study were used to quantify visual acuity. RESULTS: The patients' ages ranged from 4 to 35 years (mean age, 10.1 years). Visual acuity in the amblyopic eyes ranged from 20/20 to 20/250. The mean visual acuity difference (HOTV scores vs Lea symbols scores) was -0.056 logMAR units (P < .001), slightly more than half of a line. The negative value indicates that patients performed better on the HOTV test. In nonamblyopic eyes, the mean difference was -0.05 logMAR units (P < .001). Patients with strabismic amblyopia had a mean difference of -0.05 logMAR units (P = .08); those with anisometropic amblyopia had a mean difference of -0.07 logMAR units (P = .002). Patients 8 years and younger had a mean difference of -0.04 logMAR units (P = .05); those older than 8 years had a mean difference of -0.06 logMAR units (P = .002). CONCLUSIONS: In both amblyopic and nonamblyopic eyes, visual acuity measurements were better on HOTV testing compared with Lea symbols testing. The differences persisted regardless of patient age and the cause and severity of amblyopia. Overestimation of visual acuity by the Lea symbols test was not found.

Adolescent↗

Effects of cataract and scotoma on visual acuity: a simulation study.

Central field loss (CFL) and cataract both decrease visual acuity. For patients with CFL, visual acuity is further reduced when the acuity target is more visually complex. We tested visual acuity for targets of varying complexity (letters alone, letters flanked by one or two x's on each side, and words) in subjects with normal vision and in the presence of a simulated cataract, simulated scotoma, and their combination (scotoma + cataract). Visual acuity was best with normal vision and worst with scotoma + cataract for all of the acuity targets. There was little difference in visual acuity between the letters alone and flanked letters, and visual acuity was best for words under all vision conditions. The cataract had a greater impact on visual acuity when the subject's central visual field was clear (normal vision) than when it was occluded by the simulated scotoma.

Adult↗

[Visual acuity perimetry. Detection of glaucomatous visual field defects].

50 eyes of 50 patients with different types of glaucoma (27 eyes with POAG, 14 eyes with glaucoma due to pseudoexfoliation, 8 eyes with chronic narrow-angle glaucoma, 1 eye with normal-tension glaucoma) were examined with light-sense perimetry (Humphrey-Field-Analyzer, program 30-2) and resolution perimetry according to Frisén [2-7]. As the field area tested by Frisén's ring perimeter is smaller than that of the HFA, the comparison was restricted to the area of the ring perimeter, so that 50 out of 77 test locations of the HFA were included. In addition to a quantitative comparison with statistical criteria based on age-corrected normal values, a subjective qualitative assessment was established. The quantitative comparison of all hemifields showed good agreement in 61% of eyes, the ring perimeter indicating moderately and markedly increased numbers of defects in 13% and 4% of eyes and the HFA in 18% and 4% of eyes, respectively. Qualitative comparison of the entire fields revealed good agreement in 46% of eyes, with moderately and markedly more defects in 18% and 10% for the ring perimeter and 12% and 14% for the HFA, respectively. The average time needed for examination was 6.0 +/- 1.1 min for the ring perimeter and 17.2 +/- 2.7 min for the HFA. The Global Deviation of the ring perimeter correlates linearly with the Mean Deviation of the HFA (r = 0.4824, P < 0.001).

Adult↗

Visual acuity in premature infants.

PURPOSE: To measure grating visual acuity in premature infants and compare it with that in full-term infants. METHODS: The visual acuity of 73 premature and 73 full-term infants was tested at 6 months of age by the Teller Acuity Card procedure. All premature infants had undergone indirect funduscopy for the detection of retinopathy of prematurity (ROP). Seven infants had developed ROP. The mean gestational age of the premature infants was 33 +/- 1.4 weeks as compared with 39.9 +/- 0.9 weeks in the full-term infants. The mean birth weights of the 2 groups were 1,906 +/- 412 and 3,244 +/- 420 g, respectively. RESULTS: Impaired binocular visual acuity was found in 53.4% of the premature infants, but in only 11% of the full-term infants (p < 0.0001). Impaired monocular visual acuity was found in 13.7% of the premature infants as compared with 2.7% of the full-term infants. Within the premature infant group, monocular visual acuity was impaired in 42.9% of those with ROP and in 10.6% of those without ROP (p = 0.0497). Pathological refraction was found in 33.3% of the prematures without ROP and in 14.3% of the prematures with ROP. This difference was not statistically significant. Visual acuity of preterm infants was not different from full-term infants when examined at 6 months of postconceptual age. CONCLUSIONS: Both monocular and binocular visual acuities as measured by the Teller Acuity Cards are worse in premature infants than in full-term infants at the same chronological age. Poor visual acuity in premature infants can be attributed mainly to immaturity of the visual system.

Birth Weight↗

Comparison of measures of visual acuity in infants: Teller acuity cards and sweep visual evoked potentials.

PURPOSE: This study compares the development of acuity in the same infants during one testing session using Teller acuity cards (TAC) and sweep visual evoked potentials (sVEP). We asked whether different testing methods in two centers would produce different developmental time courses. METHODS: Forty-eight infants were tested in two centers. The standard procedure for TAC was used. For sVEP acuity, the amplitude response curve derived from time-locked cortical activity was used to extrapolate to zero response, giving an acuity estimate for each infant. RESULTS: sVEP acuity was generally higher than TAC acuity. The rate of development was steeper for TAC than sVEP acuity with TAC starting at a much lower level. The ratio of sVEP to TAC acuity decreased exponentially with age reaching an asymptote of about 1.44 at 6 months. CONCLUSIONS: Results were indistinguishable between centers suggesting that comparison of acuity measures obtained using variations of these methods across centers is possible.

Aging↗

Visual acuity impairment in patients with retinitis pigmentosa.

PURPOSE: The authors evaluated visual acuity impairment in 906 patients from 742 families with either isolated or various identifiable genetic subtypes of retinitis pigmentosa (RP) to determine the severity of their visual acuity impairment. Emphasis was placed on the prevalence of total blindness and visual acuity of 20/200 or worse in this group of patients. METHODS: This cross-sectional retrospective study included all patients with RP who met certain entrance criteria and were examined by one of the authors (GAF). The authors analyzed the eye of each patient with the best-corrected visual acuity on their most recent visit. RESULTS: Seventeen patients with a sector form of RP were excluded from the authors primary analysis. In the remaining group of 889 patients, 710 (80%) had a visual acuity of better than 20/200, 648 (73%) showed a visual acuity of 20/70 or better, and 489 (55%) had a visual acuity of 20/40 or better in at least 1 eye. Seventy-five patients (8%) had visual acuity of count fingers or worse in their best eye. There was only one patient with no light perception in each eye. Patients with autosomal dominant RP, as a group, had the least severe and those with X-linked recessive RP had the most severe impairment in visual acuity. Those with autosomal recessive disease were intermediate in severity of visual impairment. CONCLUSIONS: Analysis of visual acuity in this large group of patients with RP, which genetically is representative of patients with RP seen in the United States by those who specialize in retinal disease, showed that it was rare for the patients to lose all visual acuity from the disease itself. Further, legal blindness from visual acuity loss, defined as best-corrected visual acuity that is no better than 20/200 in at least one eye, occurred in a relatively small percentage (20%) of our patient population, whereas approximately half of all patients and 42% of those older than 60 years had a visual acuity of 20/40 or better in at least one eye. The extent of impairment in visual acuity was associated with the genetic subtype of the disease.

Adolescent↗

Repeatability of visual acuity measurement.

PURPOSE: This study investigates features of visual acuity chart design and acuity testing scoring methods which affect the validity and repeatability of visual acuity measurements. METHODS: Visual acuity was measured using the Sloan and British Standard letter series, and Landolt rings. Identifiability of the different letters as a function of size was estimated, and expressed in the form of frequency-of-seeing curves. These functions were then used to simulate acuity measurements with a variety of chart designs and scoring criteria. RESULTS: Systematic relationships exist between chart design parameters and acuity score, and acuity score repeatability. In particular, an important feature of a chart, that largely determines the repeatability of visual acuity measurement, is the amount of size change attributed to each letter. The methods used to score visual acuity performance also affect repeatability. CONCLUSIONS: It is possible to evaluate acuity score validity and repeatability using the statistical principles discussed here.

Adult↗

Ophthalmic changes from age of 10 to 18 years. A longitudinal study of sequels to low birth weight. II. Visual acuity.

Re-examination of corrected visual acuity was done in 137 18-year-old Danes, who were originally examined at the age of 10 years, as part of a study of sequels to low birth weight (LBW) (Fledelius 1976). Median values indicate that most adolescents are able visually to discriminate considerably above the customary 6/6 limit. As compared with low-birth-weighters (n=70), full-terms (n=67) show a significantly higher cumulated visual acuity score. Similarly, binocular median visual acuities are 1.2 (LBW) and 1.4 (in FT). The difference is neither explained by the ex-prematures' higher frequency of heterotropia, nor by their (minor) share of eyes with subnormal vision. The latter occurred especially in the subgroup of 'myopia of prematurity'. The exceptional cases with RLF-blindness were discarded from follow-up. Concerning visual acuity, the previously reported lagging behind of ex-prematures in childhood has proven to be not only a temporary delay, but a permanent (adult) feature.

Adolescent↗

Open globe injuries with positive intraocular cultures: factors influencing final visual acuity outcomes.

PURPOSE: To investigate the clinical features influencing final visual acuity outcomes of eyes with positive intraocular cultures after open globe injuries. DESIGN: Retrospective, consecutive, interventional case series. PARTICIPANTS: Thirty-seven patients. METHODS: The medical records were reviewed of all patients with positive intraocular cultures after open globe injuries treated at Bascom Palmer Eye Institute between January 1, 1995, and December 31, 2001. MAIN OUTCOME MEASURES: Final visual acuity. Clinical features investigated included the following: (1). presence or absence of clinical endophthalmitis; (2). virulence of the cultured organism (coagulase-negative Staphylococci, Corynebacterium, and Propionibacterium acnes were classified as nonvirulent organisms, whereas all other organisms were classified as virulent organisms); (3). presence of intraocular foreign body (IOFB); (4). presence of retinal detachment; (5). interval between ocular injury and surgical repair; (6). severity of vision loss at presentation; (7). zone of injury; (8). wound length; and (9). presence of vitreous hemorrhage. RESULTS: The study included 37 eyes of 37 patients with a mean age of 30 years (range, 18 months-85 years) and a median follow-up of 13 months (range, 1-71 months). Study eyes were stratified into two groups: group 1 eyes (n = 16) were those in which clinical endophthalmitis did not develop, whereas group 2 eyes (n = 21) were those in which clinically diagnosed endophthalmitis developed at some point during their clinical course. Presenting visual acuity was similar in the two groups (mean logarithm of the minimum angle of resolution [logMAR] acuity, 1.91 and 2.22 [Snellen equivalents, 2/162 and 2/331] respectively; P = 0.33). Final acuities in the two groups were different, but not to a statistically significant level (mean logMAR acuity, 1.14 and 2.05 [Snellen equivalents, 20/276 and 2/224], respectively; P = 0.069). In group 1, final visual acuity ranged from 20/20 to no light perception (median acuity, 20/186); 12 eyes (75.0%) achieved a final visual acuity of 20/400 or better. In group 2, final visual acuity ranged from 20/25 to no light perception (median acuity, 7/200); of 20 eyes with known final visual acuity, 10 (50.0%) retained 20/400 or better vision. In group 1, three eyes (19%) eyes had virulent organisms, and 13 eyes (81%) had nonvirulent organisms. In group 2, 12 eyes (57%) had virulent organisms, and nine eyes (43%) had nonvirulent organisms. A final acuity of 20/60 or better was achieved in 14 eyes (41%), and a final acuity of 20/400 or better was achieved in 22 eyes (59%). Better presenting visual acuity (P = 0.038), culture of a nonvirulent organism (P = 0.011), lack of a retinal detachment (P = 0.002), absence of clinical endophthalmitis (P = 0.069), and shorter wound length (P = 0.024) were associated with better visual acuity outcome. In four of six eyes (67%) with both an IOFB and clinical endophthalmitis (group 2), the final visual acuity was no light perception (IOFB was not itself significantly associated with final visual acuity; P = 0.11). CONCLUSIONS: Among eyes with positive intraocular cultures after open globe injury, the visual prognosis is guarded. Clinical features associated with better visual acuity outcomes include better presenting visual acuity, culture of a nonvirulent organism, lack of a retinal detachment, absence of clinical endophthalmitis, and shorter wound length.

Adolescent↗