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PubMed2001

Factors Influencing Visual Acuity Following Vitrectomy for Exudative Age-related Macular Degeneration.

Purpose: We investigated the influence of various factors on visual results in patients undergoing surgical removal of choroidal neovascular membranes (CNVM) caused by age-related macular degeneration (AMD).Subjects and Methods: This study was performed in 55 eyes of 55 patients who underwent surgical removal of CNVM for AMD and followed them for 6 months or more. The criterion for surgical eligibility was active subfoveal choroidal neovascular membrane of 0.5 or more disc diameter above the retinal pigment epithelium with visual acuity of 0.3 or worse. We investigated the influence of various factors on the logarithm of the minimum angle of resolution (log MAR) final visual acuity. The factors were age, symptom duration, preoperative log MAR visual acuity, CNVM diameter, mean deviation with visual field analyzer, previous laser treatment, posterior vitreous detachment, findings of indocyanine green angiography, operative complications, and recurrence of CNVM.Results: Better preoperative visual acuity, shorter symptom duration, and smaller CNVM diameter were correlated with better postoperative final visual acuity.Conclusions: Surgical excision of subfoveal CNVM may be the better therapeutic choice in selected cases with AMD.

Journal Article↗

PubMed2006

Causes of visual acuity loss among patients with AIDS and cytomegalovirus retinitis in the era of highly active antiretroviral therapy.

PURPOSE: To quantitate the frequencies of the common causes of visual acuity loss for patients with AIDS and cytomegalovirus (CMV) retinitis in the era of highly active antiretroviral therapy (HAART). DESIGN: Multicenter prospective observational study. PARTICIPANTS: Three hundred seventy-nine patients (494 eyes) with CMV retinitis. METHODS: Follow-up every 3 months with medical history, ophthalmologic examination, and laboratory testing. MAIN OUTCOME MEASURES: Loss of visual acuity across the 20/50 or worse and 20/200 or worse thresholds and doubling of the visual angle; frequencies of causes of such vision loss. RESULTS: Overall, involvement of the posterior pole with CMV retinitis (zone 1 retinitis) accounted for approximately one half of incident visual acuity loss of 20/50 or worse, 20/200 or worse, and of doubling of the visual angle. Cataract and retinitis-related retinal detachment were the second and third most common causes of vision loss, accounting for 22% to 33% and 13% to 20% of vision loss for the 3 outcomes, respectively. In subset analysis, cataract and cystoid macular edema (CME) accounted for approximately 50% of incident vision loss in eyes of patients with longstanding CMV retinitis and immune recovery at baseline, but these complications accounted for <10% of incident vision loss in eyes of patients with newly diagnosed CMV retinitis at baseline. Of eyes that had a vision-threatening complication of CMV retinitis, eyes that developed retinal detachment had the highest risk of vision loss, with 100% of eyes developing visual impairment (20/50 or worse vision) and 42% of eyes developing legal blindness (20/200 or worse vision) at 12 months after diagnosis of the retinal detachment. CONCLUSIONS: In the HAART era, zone 1 involvement and retinal detachment remain the most common causes of visual acuity loss among patients with CMV retinitis. Cataract and CME also are common causes of loss of visual acuity, primarily in those patients with HAART-induced immune recovery.

Acquired Immunodeficiency Syndrome↗

PubMedDate not supplied

Improvement of visual acuity in eyes with diabetic macular edema after treatment with pars plana vitrectomy.

BACKGROUND: Diabetic macular edema (DME) is the leading cause of severe visual loss in patients with diabetic retinopathy. This is so despite the fact that argon laser photocoagulation of the macula (M-ALC) has been shown to be beneficial. Recently, it has been suggested that pars plana vitrectomy (PPV) can lead to the resolution of DME and stop the deterioration of central visual acuity. PURPOSE: To explore the potential benefit of PPV for the treatment of DME. PATIENTS AND METHODS: PPV was carried out in 30 eyes of 21 consecutive patients (median age 71 years, range 61-88 years) with type II diabetes mellitus suffering from DME. 23 eyes had non-proliferative diabetic retinopathy (NPDR) and 7 eyes had proliferative diabetic retinopathy (PDR) in addition to DME. Posterior vitreous detachment had to be carried out in all cases. If epiretinal membranes were present (23 eyes), they were removed. In 13 eyes (initially 11 eyes) the internal limiting membrane (ILM) was also removed. Prior to PPV 8 eyes had received M-ALC. Three eyes had M-ALC after PPV. One eye developed a retinal detachment 6 weeks after PPV and was excluded form the analysis. After an initial treatment failure two eyes underwent repeat PPV with peeling of the ILM. Both eyes of another patient had 2 repeat PPVs because of recurrent vitreous hemorrhage. Median follow-up was 16 months (range 1-62 months). RESULTS: Following PPV the macula flattened or became attached in 20/27 (74%) eyes. 15/18 (83%) eyes showed reduction or disappearance of leakage during fluorescein-angiography. Central visual acuity increased by two to six lines in 15/27 (56%) for the whole group at 6 months after PPV. For the subgroup (18 eyes) for which the evolution of visual acuity prior to PPV could be documented mean and median visual acuity had decreased markedly from 0.26 +/- 0.19 resp. 0.2 (range 0.03-0.6) to 0.12 +/- 0.09 resp. 0.1 (range 0.02-0.4) during the 12 months preceding PPV and increased to 0.28 +/- 0.23 resp. 0.2 (range 0.03-0.8) during the 12 months following PPV. CONCLUSION: PPV almost always results in a reduction and often complete disappearance of DME as evidenced by ophthalmoscopy and fluorescein-angiography. Most importantly, central visual acuity often increases, sometimes to a very large extent with dramatic improvement in quality of life of the patients.

Aged↗

PubMed1978

Dynamic visual acuity: a possible factor in catching performance.

Forty subjects took part in a one-handed catching ask in which the period for which the mechanically projected tennis ball was illuminated in flight was varied systematically. Additionally, they were tested for (a) static visual acuity and (b) dynamic visual acuity, in which angular velocity was varied. As expected, both viewing period in the catching task and angular velocity in the acuity task were significant variables in performance. Correlation and principal-components analyses confirmed the findings of a previous experiment in that the correlated static visual acuity tasks were unrelated to both dynamic visual acuity (even when angular velocity was only 75 degrees /sec) and catching performance. Further, dynamic acuity and catching were related under the majority of the combinations, and most frequently at the highest angular velocity, a fact which suggested that the dynamic element in both tasks is the common factor.

Journal Article↗

PubMed1986

A new method for exact measurements of visual acuity. Determination of threshold curves for the resolving power of the eye by computerized curve fitting.

The paper presents a new test method for investigations of threshold curves for the resolving power of the eye and for exact measurements of visual acuity. This method measures static visual acuity within confidence limits of 9% compared to the acuity steps in Snellen notation of 33% to 50%. Furthermore, the method introduces the slope of the threshold curve as a parameter of suggested importance in the judgement of visual capability. The test mathematic is based on a method described by Finney (1952) for calculations on dose-response curves. To calculate the results and the test statistics an iterative curve fitting programme was designed to be run on a micro-computer. By connecting the presentation system and the response panel to the same computer the test could be performed almost automatically. The new test method was used to study visual acuity measured by projected ortotypes compared to acuity when measured by printed ortotypes. Tests using projected ortotypes were found to equal traditional acuity measurements, but the test results stressed the need for perfect and adjusted optics when projecting systems are used in visual acuity test.

Computers↗

PubMed1998

[Effect of exposure time using single landolt-rings on visual acuity in normal individuals and patients with nystagmus].

BACKGROUND: The recommendations of the German Society of Ophthalmology (DOG) concerning the examination of candidates or holders of a driving licence allow a maximum time interval of 1 s for identifying a single Landolt-C for normal individuals as well as for patients with nystagmus. The aim of this study was to determine whether visual acuity decreases with shortening of the exposure time. PATIENTS AND METHODS: We measured the visual acuity of 18 patients with manifest nystagmus and 26 normal individuals with single Landolt-C at exposure times of 10 s, 1 s, 0.25 s and 0.1 s. RESULTS: Visual acuity dropped significantly at exposure times of 1 s in the group of patients with nystagmus (P = 0.01). In normal individuals, visual acuity decreased significantly only at exposure times below 1 s. CONCLUSION: Determining visual acuity according to the recommendations of the DOG shows a significant drop of visual acuity in nystagmus patients, but not in normal individuals. Applying the maximum time limit of 1 s exposure time to these patients will ensure that they will be able to identify traffic signs quickly and orient themselves safely.

Adult↗

PubMed2005

[Variation of visual acuity in young patients with ectopia lentis submitted to surgery].

PURPOSE: To assess the results as to visual acuity of two different surgical procedures for ectopia lentis. METHODS: Fifty-one eyes of 28 patients (16 males and 12 females, mean age 16.00 +/- 8.5) with simple (19 cases) or Marfan syndrome-associated (9 cases) ectopia lentis with different levels of subluxation underwent lens extraction with implantation of intraocular lenses (IOL) with scleral fixation (21 cases) or by lens extraction with implantation of the intraocular lenses in the capsular bag expanded by endocapsular ring (RING) (30 cases). Result analysis emphasized pre- and postoperative visual acuity during a six-month follow-up. RESULTS: Both techniques showed significant increase of postoperative visual acuity with and without correction, but it was better among the cases operated on by scleral fixation of the intraocular lenses. More than the used technique, the preoperative subluxation grades were crucial as to the results. CONCLUSION: The two surgical techniques for correction of simple or Marfan syndrome-associated ectopia lentis are safe and effective, resulting in significant recovery of visual acuity, although surgical results are completely dependent on the preoperative lens subluxation grades.

Adolescent↗

PubMed2005

Impaired contrast sensitivity among leprosy patients with normal visual acuity.

Contrast sensitivity is a person's ability to identify an object from its background. Patients with normal visual acuity can have reduced contrast sensitivity and may experience trouble in identifying objects at night or moving around in dimly lit places. Contrast sensitivity has never been studied in leprosy patients having normal visual acuity. This study aimed to determine if contrast sensitivity is impaired in leprosy patients who have normal visual acuity and to identify possible associations with demographic, leprosy and ocular characteristics. A hospital based study measuring and comparing contrast sensitivity using the VCT 6500 chart in 127 consecutive leprosy patients without clinically apparent ocular complications and 123 non-leprosy controls was done. Contrast sensitivity was impaired in leprosy patients in all five spatial frequencies (1.5, 3.0, 6.0, 12 and 18 cycles/degree) investigated. Among leprosy patients, contrast sensitivity falling outside the normative range was associated with increasing age (adjusted OR 1.28, 95% CI: 1.14-1.42), being female (adjusted OR 11.05, 95% CI: 2.93-41.69) and having a grade 2 deformity (adjusted OR 6.43, 95% CI:1.68-24.61). Contrast sensitivity is impaired in leprosy patients having normal visual acuity. Elderly, deformed, female patients are particularly burdened with this vision loss.

Adolescent↗

PubMed1987

Relationship between refractive error and visual acuity in the Prospective Evaluation of Radial Keratotomy (PERK) Study.

As part of the Prospective Evaluation of Radial Keratotomy (PERK) study, we examined the relationship between post-operative refractive error and visual acuity without correction. We included 394 eyes (one eye per patient) with refractive errors ranging from -3.00 to +3.00 diopters one year after radial keratotomy. Within each 1-D range of the spherical equivalent of the refractive error, the visual acuity spanned five to ten Snellen lines. For visual acuities of 20/16 to 20/50, the refractive error spanned 3 to 5 D. Additionally, operated eyes had a better average uncorrected visual acuity than unoperated eyes with a similar refractive error. Within the narrow range of refraction between -2.00 and -2.50 D, the mean uncorrected visual acuity was 20/125 for 56 unoperated eyes and 20/63 for 29 operated eyes, a difference of three Snellen lines.

Adult↗

PubMed2006

Incidence of and risk factors for visual acuity loss among patients with AIDS and cytomegalovirus retinitis in the era of highly active antiretroviral therapy.

PURPOSE: To describe the incidence of and risk factors for visual acuity loss among patients with AIDS and cytomegalovirus (CMV) retinitis in the era of highly active antiretroviral therapy (HAART). DESIGN: Multicenter prospective observational study. PARTICIPANTS: Three hundred seventy-nine patients with AIDS and CMV retinitis (494 eyes). METHODS: Follow-up every 3 months with medical history, ophthalmologic examination, and laboratory testing. MAIN OUTCOME MEASURES: Incidence of visual acuity loss to 20/50 or worse, to 20/200 or worse, and of doubling of the visual angle in eyes affected with CMV retinitis. RESULTS: Among the 494 eyes with CMV retinitis, the baseline frequencies of visual acuity loss to 20/50 or worse and to 20/200 or worse were 29% and 15%, respectively. Over a median follow-up period of 3.1 years, the incidences of visual acuity loss to 20/50 or worse, to 20/200 or worse, and of doubling of the visual angle were 0.10/eye-year (EY), 0.06/EY, and 0.13/EY, respectively. Immune recovery was associated with a 42% reduction in vision loss to 20/50 or worse and with a 61% reduction in vision loss to 20/200 or worse after adjusting for confounding. Of the patients with immune recovery at baseline, 17% had immune recovery uveitis (IRU). In these patients, the incidence rate of 20/50 or worse vision was similar to that observed in patients without immune recovery (0.17/EY vs. 0.16/EY), but the incidence of 20/200 or worse vision was similar to that observed among patients with immune recovery (0.04/EY vs. 0.04/EY). CONCLUSIONS: Cytomegalovirus retinitis is associated with a substantial risk of incident vision loss in the era of HAART. Those who have HAART-induced immune recovery have approximately 50% lower risk of visual acuity loss. Presence of IRU at baseline attenuated the protective effect of immune recovery for moderate vision loss but not for blindness.

Acquired Immunodeficiency Syndrome↗

PubMed1999

Correlation of quantitative three-dimensional measurements of macular hole size with visual acuity after vitrectomy.

OBJECTIVE: The purpose of the study was to study the relationship of postoperative visual outcome with anatomical parameters of macular holes using confocal scanning laser tomography and to predict the postoperative visual results. DESIGN: Cohort study. INTERVENTION AND PARTICIPANTS: We evaluated the eyes of 44 patients undergoing macular hole surgery (10 men and 34 women aged 40-76 years, mean 59.1 years). All patients showed idiopathic full-thickness stage 3 macular holes. The duration of symptoms was 1-4 months (mean 2.7 months). MAIN OUTCOME MEASURES: The area, volume, mean depth, and maximum depth of the macular holes and the areas of cuff and retinal striae were measured using the Heidelberg Retina Tomograph preoperatively. RESULTS: All 44 eyes showed closure of the holes and flattening of cuff and retinal striae after vitrectomy and gas tamponade. Postoperative visual acuity was significantly correlated with the area (r = 0.822, P<0.0001), volume (r = 0.840, P<0.0001), mean depth (r = 0.842, P<0.0001), and maximum depth (r = 0.831, P<0.0001) of the macular holes, area of cuff (r = 0.625, P<0.0001), and area of retinal striae (r = 0.648, P<0.0001). Multiple regression analysis showed that the combination of the preoperative mean depth of macular holes and logarithm of preoperative visual acuity was the strongest predictor of the postoperative visual acuity. CONCLUSIONS: Postoperative visual results vary significantly with the size of macular holes in patients with stage 3 macular holes of duration 1-4 months. The use of the confocal scanning laser tomography may facilitate the evaluation of macular holes before surgery. Ability to predict the postoperative visual results would be helpful in treating patients with macular holes.

Adult↗

PubMed2004

Unequal reduction in visual acuity with positive and negative defocusing lenses in myopes.

Myopes have a reduced accommodative response to negative lenses compared with nonmyopes. Mathematical models predict that the reduced accommodative response is due to a decrease in sensitivity to blur in myopes. We examined the effect of blur induced by positive and negative defocusing lenses on visual acuity in 12 myopes and 12 nonmyopes during cycloplegia for up to +/-3.00 D of defocus in 0.25 D steps. Although nonmyopes showed a symmetrical reduction in visual acuity with positive and negative lenses, the myopic group showed less acuity loss with negative lenses compared with positive lenses. The magnitude of visual acuity loss was lower with negative lenses in myopes compared with nonmyopes. No significant difference in visual acuity with positive lenses was found between myopes and nonmyopes. Residual accommodation (after cycloplegia) was about 0.20 D in both myopes and nonmyopes and was too small to explain the relatively good visual acuity through minus lenses in the myopic group. The reduced accommodative response known to occur in myopes may be due to the relatively small effect that negative lens blur has on their visual acuity.

Accommodation, Ocular↗

PubMed1989

From visual acuity to hyperacuity: a 10-year update.

Visual acuity, the most basic measure of developing pattern vision in human infants, has been used extensively for detecting anomalies of vision and oculomotor coordination. In the past 10 years much has been learned about the development of two hyperacuities, namely, vernier acuity and stereoacuity. These two acuities become superior to grating acuity after the third month and remain so throughout life. Compared to females, males show slower development of stereopsis and vernier acuity, but not grating acuity, during the third through sixth months. We have suggested that this may result from the neurotrophic effects of the early pulse of testosterone found in males. Measures of vernier acuity have proven effective in detecting meridional amblyopia in older children who had significant astigmatism in the first year and subsequently lost it. The susceptible period for acquiring meridional amblyopia extends from the second half of the first year to at least the end of the second year. Deviations from the typical oblique effect (equal acuity for vertical and horizontal edges; equal, but lower, acuity for left oblique and right oblique) may result from uncorrected astigmatism early in life.

Amblyopia↗

PubMed1983

Canine visual acuity: retinal and cortical field potentials evoked by pattern stimulation.

The visual acuities (i.e., visual thresholds for pattern detection) of four dogs under neuromuscular block were measured using visually evoked cortical potentials (VECP) and/or pattern-evoked retinal potentials (PERR). Stimuli were phase-reversing square-wave gratings with a mean luminance of 86 cd/m2 and 70% contrast. The mean of the VECP thresholds of two dogs tested was 12.59 cycles per degree (cycles/deg). The mean of the PERR thresholds of four dogs tested was 11.61 cycles/deg. The difference between VECP and PERR thresholds was not statistically significant. VECP acuities appear to be determined at or before the last stage of retinal processing (PERR). Our estimates of canine acuity are 1.3-2 times those reported for cats and 0.2-0.4 times those reported for primates when tested under comparable luminance and contrast conditions.

Animals↗

PubMedDate not supplied

Diabetic retinopathy, visual acuity, and medical risk indicators: a continuous 10-year follow-up study in Type 1 diabetic patients under routine care.

The objective of this study was to describe incidence and progression of diabetic retinopathy in relation to medical risk indicators as well as visual acuity outcome after a continuous follow-up period of 10 years in a Type 1 diabetic population treated under routine care. The incidence and progression of retinopathy and their association to HbA(1c), blood pressure, urinary albumin, serum creatinine levels, and insulin dosage were studied prospectively in 452 Type 1 diabetic patients. The degree of retinopathy was classified as no retinopathy, background, or sight-threatening retinopathy, i.e. clinically significant macular edema, severe nonproliferative, or proliferative retinopathy. Impaired visual acuity was defined as a visual acuity <0.5 and blindness as a visual acuity < or =0.1 in the best eye. In patients still alive at follow-up (n=344), 61% (69/114) developed any retinopathy, 45% (51/114) background retinopathy, and 16% (18/114) sight-threatening retinopathy. Progression from background to sight-threatening retinopathy occurred in 56% (73/131). In 2% (6/335), visual acuity dropped to <0.5 and in less than 1% (3/340) to < or =0.1. Patients who developed any retinopathy and patients who progressed to sight-threatening retinopathy had higher mean HbA(1c) levels over time compared to those who remained stable (P<.001 in both cases). Patients who developed any retinopathy had higher levels of mean diastolic blood pressure (P=.036), whereas no differences were seen in systolic blood pressure levels between the groups. Cox regression analysis, including all patients, showed mean HbA(1c) to be an independent risk indicator for both development and progression of retinopathy, whereas mean diastolic blood pressure was only a risk indicator for the incidence of retinopathy. Metabolic control is an important risk indicator for both development and progression of retinopathy, whereas diastolic blood pressure is important for the development of retinopathy in Type 1 diabetes. The number of patients who became blind during 10 years of follow-up was low.

Adult↗

PubMedDate not supplied

Measuring visual acuity in infants.

This paper reviews the course of development of visual acuity in human infants and young children. Researchers have devised methods based on optokinetic nystagmus, visually evoked cortical potentials and preferential looking to assess visual acuity in infants and preverbal youngsters. During the first postnatal year and early childhood, acuity, measured by any of these methods, improves with increasing age. Each of these methods, has now been applied to the evaluation of clinical cases. Also presented are the results of a quick and simple test based on preferential looking, which has been incorporated into our clinical evaluation of infants. The data so far indicate that infants with normal eyes pass the test while infants with ocular problems which would interfere with vision fail. For evaluation of large numbers of infants this test appears to have the potential to assist nonspecialized personnel in the early identification of ophthalmic abnormalities.

Age Factors↗

PubMed1999

Change in retinal sensitivity due to excision of choroidal neovascularization and its influence on visual acuity outcome.

PURPOSE: Excision of choroidal neovascular membranes (CNV) has been attempted as an alternative to photocoagulation for the management of subfoveal CNV. To evaluate functional results of CNV excision, we studied retinal sensitivity in the area corresponding to the CNV (CNV area). METHODS: Static microperimetry using a scanning laser ophthalmoscope was performed on 17 eyes before and after CNV excision. We studied whether CNV excision changed retinal sensitivity in the CNV area. To evaluate the relationship between retinal sensitivity and visual acuity, further testing was performed on nine patients who had subfoveal CNV from age-related macular degeneration (ARMD). RESULTS: Preoperatively, 5 of 17 eyes (29.4%) had retinal sensitivity in the CNV area. Postoperatively, 4 of 17 (23.5%) eyes had retinal sensitivity. Surgery did not significantly change retinal sensitivity in the CNV area (P>0.999). There was a significant correlation between the presence of retinal sensitivity and visual acuity. Postoperative visual acuity of eyes with retinal sensitivity in the CNV area was better than that of the eyes without sensitivity in the patients with subfoveal CNV from ARMD (P = 0.0017). CONCLUSIONS: In most cases, excision of CNV does not improve central retinal sensitivity, and patients have poor visual outcome. In some cases, however, postoperative sensitivity in the bed of CNV is preserved and visual outcome is relatively good. Better or worse preoperative retinal sensitivity does not predict better or worse visual acuity outcome, respectively.

Adult↗

PubMed2006

Visual acuity, contrast sensitivity, and mortality in older women: Study of osteoporotic fractures.

OBJECTIVES: To determine whether poorer visual acuity and contrast sensitivity are independent risk factors for all-cause and traumatic mortality in older women. DESIGN: Twelve-year prospective cohort study (1986-2003). SETTING: Four U.S. clinical centers. PARTICIPANTS: Nine thousand seven hundred four postmenopausal white women aged 65 and older. MEASUREMENTS: Habitually corrected binocular visual acuity and low- and high-frequency contrast sensitivity were measured at baseline using a standard protocol. A study physician adjudicated the primary cause of death from death certificates and medical record review. RESULTS: During an average of 12.2 years of follow-up, 3,427 women died (35%), 72 (0.7%) from traumatic events. In multivariate models adjusted for age, chronic medical problems, and smoking, all-cause mortality risk was 19% greater for persons in the worst quartile of visual acuity than for those in the best (hazard ratio (HR) = 1.19, P = .008) and 39% greater for persons with the worst contrast sensitivity (HR = 1.39, P < .001) than for those with the best. Traumatic mortality risk was 2.4 times greater for women with the worst contrast sensitivity than for those with the best (HR = 2.44, P = .03). CONCLUSION: Poorer visual acuity and contrast sensitivity are associated with greater risk of traumatic and all-cause mortality in older women, even after controlling for demographic and clinical characteristics. Although further research is necessary to determine how treating reversible causes of visual impairment or improving current refraction affects mortality in older women, clinical detection and follow-up of these visual impairments holds promise for identifying those who are at risk of mortality from other systemic conditions.

Aged↗