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PubMed1995

Visual acuity in a population aged 70 years or older; prevalence and causes of visual impairment.

Visual acuity and the prevalence and causes of impaired vision were studied in an epidemiological cross-sectional population study of inhabitants aged 70 years or older in three communities in the county of Oulu, Finland. 500 of the 560 eligible persons (89.3%) were examined. Information on visual acuity was obtained for 476 co-operative persons (85.0%). 59.0% had a visual acuity of 0.3-0.6 in the better eye. 10.1% (48 persons) had low vision and 1.9% (9 persons) were blind as categorized according to the classification of visual impairment by the World Health Organization. Experienced visual capacity did not, however, always correspond to objective tests. Age-related maculopathy and cataract were the leading causes of visual deterioration. Age-related maculopathy was the main cause of low vision and blindness in 4.6% of the population. In 1.3% the etiology was cataract, and in 2.1% both early age-related maculopathy and cataract were present without obvious dominance. Cataract was often associated with other conditions. Glaucoma was considered the main cause of visual deterioration in 1.5%, diabetic maculopathy in 0.6% and macula pucker in 0.4%. In 1.5% the visual deterioration was due to other causes.

Aged↗

PubMed1999

Variability of measurements of visual acuity in a large eye clinic.

PURPOSE: The aim of this study was to determine the variability of visual acuity in a large eye clinic. METHODS: A cross-sectional study using 50, consecutively presenting adult patients with visual acuity of at least 6/60 and aged between 18 and 75 years was performed. Measurements of visual acuity obtained under normal clinical conditions were compared to measurements obtained using standard clinical research protocols. The variability of visual acuity was assessed by determining the 95% limits of agreement between test and retest measures. RESULTS: There were no significant differences between test-retest measurements of visual acuity, either aided or unaided. Pearson r correlation coefficients between test and retest measurements were high for both aided and unaided visual acuity. The 95% limits of agreement revealed repeatability of about +/-1.5 logMAR or 1.5 lines on a standard logMAR chart. CONCLUSION: In large eye clinics, in order to be confident that a real change in visual acuity has occurred between measurements, a difference of at least 0.15 logMAR (8 letters on a standard logMAR visual acuity chart) is required.

Adolescent↗

PubMed2000

Veterans Affairs Multicenter Low Vision Enhancement System (LVES) study: clinical results. Report 1: effects of manual-focus LVES on visual acuity and contrast sensitivity.

PURPOSE: The Department of Veterans Affairs LVES Study is a multicenter study to determine the effectiveness of the Low Vision Enhancement System (LVES) as a visual rehabilitation device. The purpose of this study was to explore the efficacy of the Beta 1 manual-focus LVES for improving visual acuity and contrast sensitivity. METHODS: Patients whose visual acuity was 20/80 or worse in the better eye from any disease, who did not have significant visual field loss, who had previous low vision experience and were capable of working with the LVES were enrolled in a comprehensive prospective multicenter clinical evaluation. Initially, corrected spectacle visual acuities were measured using a standardized ETDRS chart. Contrast sensitivities were also measured with spectacle correction using a standardized Peli-Robson chart. These results were then compared to the acuities and contrast sensitivity obtained with the LVES at optimal magnification. Also, visual acuities were measured using an Eschenbach 3x spectacle-mounted binocular telescope, then compared to the acuities obtained using the LVES set at the lowest magnification (3x). RESULTS: All patients who completed the study demonstrated an improvement in visual acuity, with a median improvement of six lines of Snellen equivalent acuity using the LVES. Improvement in visual acuity was the same in both ARMD and non-ARMD causes of vision loss. Mean contrast sensitivity improved in 52 of 58 patients tested, with a mean improvement of 0.49 log units. CONCLUSION: The LVES significantly improves both visual acuity and contrast sensitivity in visually impaired patients who fall within the study criteria. Up to 10-fold improvement in visual acuity and up to 1.80 log units improvement in contrast sensitivity were noted in the study group when the LVES was used.

Adult↗

PubMed1976

[Age dependence of visual acuity after incomplicated cataractoperation (author's transl)].

The results of visual acuity in 1523 cataract-extractions were evaluated; comparing the visual acuity of the 7th to the 9th postoperative days, when the patients left the hospital. 73,1% of the patients had a supplemental disease of the eye or another general disease. 76,6% of the patients had a postoperative visual acuity between 5/4 and 5/15, clearly depending on the age of the patients. General diseases influence scarcely surgery, but the older the patients the more we find a reduced visual acuity that is reduced by generative senile macula disease. On an average they stayed in hospital for 9,4 days.

Age Factors↗

PubMed1999

Early nutrition, essential fatty acid status and visual acuity of term infants at 7 months of age.

OBJECTIVE: In term infants the relationship between visual acuity and dietary fatty acid composition is not consistent, possibly due to confounders, which were mostly neglected in the studies concerned. In the current study, therefore, the influence of the essential fatty acid status and potential confounders on the visual acuity was investigated. DESIGN: The essential fatty acid status was determined at 7 months of age in red blood cell and plasma phospholipids of breastfed and formula-fed infants, born at term. Visual acuity was measured with Teller Acuity Cards. Information about potential confounding factors was obtained during an interview and with a retrospective questionnaire. RESULTS: This study, like others, showed that the concentrations of docosahexaenoic acid (DHA, 22:6n-3) are lower in plasma and red blood cell phospolipids of formula-fed infants compared to that of breastfed infants. However, no differences in visual acuity could be found between the two groups. Moreover, no significant relationship was found between the amounts of docosahexaenoic acid in plasma and red blood cell phospholipids and the visual acuity. Although dummy (pacifier) use showed a significant positive correlation with visual acuity, it did not influence the relationship between the essential fatty acids in the infant diet and visual acuity. There was also no confounding influence of smoking habits and alcohol use during pregnancy, socioeconomic background and other potential confounders. CONCLUSIONS: At 7 months of age no influence of fatty acid status, infant diet or potential confounders on visual acuity was found.

Breast Feeding↗

PubMed1977

Relation of visual acuity to illumination, contrast, and distance in the partially sighted.

Visual acuity (minimum target size for threshold visibility) was measured as a function of luminance, contrast, and distance in experiments using 16 partially sighted persons. The results indicate large individual differences in dependence of visual acuity on both luminance and contrast. Visual acuity often failed to change systematically with variations in the testing distance; the effects of contrast and luminence on visual acuity also frequently failed to show any systematic dependence on viewing distance. The relation of acuity in the partially sighted to medical diagnosis is discussed along with some practical implications.

Albinism↗

PubMed2002

Comparison of visual acuities at different distances and defocus curves.

PURPOSE: To evaluate how visual acuities at different distances correlate with results from defocus curves. SETTING: Department of Ophthalmology and Institute of Medical Physics, University of Vienna, Medical School, Vienna, and Department of Ophthalmology, Krankenhaus St. Pölten, St. Pölten, Austria. METHODS: This study comprised 15 eyes of 14 patients with a mean age of 67.9 years +/- 9.7 (SD) with a monofocal silicone intraocular lens (911A, Pharmacia). The best corrected distance visual acuity was determined at viewing distances of 6 m, 2 m, 1 m, 67 cm, 50 cm, 40 cm, and 33 cm using logMAR charts. Defocus curves were then evaluated from -3.0 to -0.5 diopter (D) at 0.5 D increments from the best distance correction at a viewing distance of 6 m. RESULTS: The mean distance visual acuity was logMAR 0.08 +/- 0.07. The visual acuity graph from the testing at different distances was above the defocus graph at all testing points. Comparison of the visual acuity results from the 2 tests revealed statistically significant differences in the range from 2 m (-0.5 D) to 33 cm (-3.0 D). CONCLUSIONS: Results of defocus curves disregard the diminutions of minus glasses, the normally restricted viewing distance to 6 m for distance acuity determination, and in particular the physiological miosis caused by the near-point reaction.

Aged↗

PubMed2001

Updating the classical approach to visual acuity.

The classical account of visual acuity incorporates optical, anatomical and physiological components. Knowledge of these helps to put into perspective recent scientific advances that have clinical implications. They include the development of active optical devices for neutralising aberrations in peripheral zones of the pupil, with the potential of improving the eye's imagery beyond its customary limit. In another application of modern optical and electronic instrumentation, the quality of retinal images in young eyes has been compared with that in the aged. This has led to a better understanding of the choice of contrast patterns to enhance visual acuity in older patients.

Journal Article↗

PubMed1991

Visual acuity and contrast sensitivity in relation to falls in an elderly population.

Visual acuity and contrast sensitivity were measured in 95 residents of a hostel for the aged (mean age = 83 years) using a dual-contrast letter chart and the Melbourne Edge Test (MET). Vision (as measured by visual acuity, the MET, low-contrast visual acuity, and difference between high- and low-contrast acuity) decreased significantly with age and all four measures were significantly correlated. Subjects with a clinical eye disorder had poorer vision than those without a disorder although the differences were not significant. Visual acuity and contrast sensitivity were not associated with body sway when subjects were standing on a firm base. However, when the subjects were placed in a situation which provided reduced support (standing on a compliant surface), body sway was associated with poor visual acuity and contrast sensitivity. There was also a difference in contrast sensitivity between those who fell one or more times in a year of follow-up and those who did not fall. It appears that reduced vision may be a predisposing factor to postural imbalance and falls in elderly persons.

Accidental Falls↗

PubMed1985

Binocular competitive interactions and recovery of visual acuity in long-term monocularly deprived cats.

Changes in visual acuity brought about by altering competitive interactions between the eyes of cats monocularly deprived (MD) from natural eye opening to 7-12 months of age were studied. In MD cats given binocular experience, median visual acuity using the deprived eye was 0.75 c/deg. If the deprived eye was given a slight competitive advantage via reverse-suture, median visual acuity reached 1.52 c/deg. Further, giving the deprived eye the greatest competitive advantage was accomplished by complete removal of the experienced eye which yielded a median deprived eye acuity of 2.3 c/deg. Obstacle avoidance and stimulus size data were also obtained. The previously published electrophysiological effects of these manipulations on striate cortical cells were noted to mirror these increases in visual acuity and this correlation was discussed, as were the effects of analogous manipulations in the monkey and man.

Animals↗

PubMed1978

Screening for impaired visual acuity in middle age in general practice.

Screening for impaired distant visual acuity was one component of a controlled trial of multiphasic screening in middle age carried out in two general practices. The prevalence of impaired visual acuity (6/18 or worse in the better eye) at the initial screening in 1967 was 9.6% overall, ranging from 5.9% in people aged 40-49 years to 16.3% in those aged over 60. The question "Do you have difficulty seeing distant objects?" had a low sensitivity and high specificity, rendering it unsatisfactory for use in mass population screening for visual impairment. The prevalences of impaired visual acuity in the screening and control groups at the survey in 1972 showed no significant differences in any age group. Mass screening for defects of visual acuity in the course of a multiphasic examination is thus unlikely to reduce the prevalence of impaired distant visual acuity in the community.

Adult↗

PubMed1990

[Role of the vitreous in idiopathic preretinal macular fibrosis indicated by visual acuity in follow-up cases].

The vitreous and visual acuity in 103 eyes with idiopathic preretinal macular fibrosis were examined. The vitreous was studied biomicroscopically and the follow-up course was 6 months or more. Twenty-two eyes had no posterior vitreous detachment (group 1), 4 eyes had partial posterior vitreous detachment without traction to the macula (group 2), 17 eyes had partial posterior vitreous detachment with traction to the macula (group 3), and 60 eyes had complete posterior vitreous detachment (group 4). There were significantly more eyes with a visual acuity of 0.4 or worse, decreased acuity, or macular fluorescein leakage in group 3 than in groups 1 or 4. Decreased visual acuity was found in 41% of eyes with macular fluorescein leakage, but in only 11% of eyes without macular fluorescein leakage. It is presumed that the vitreous traction to the macula and macular fluorescein leakage are closely related to the outcome of visual acuity in cases with idiopathic preretinal macular fibrosis.

Adolescent↗

PubMed1993

Visual acuity in patients with best vitelliform macular dystrophy.

PURPOSE: Forty-seven patients with Best vitelliform macular dystrophy were evaluated in a cross-sectional fashion for visual acuity loss with age. METHODS: The authors assessed only patients who had at least one eye with a recognizable phenotype of Best vitelliform macular dystrophy. Patients with absent foveal changes or with only minimal foveal pigment mottling and hypopigmentation in each eye were excluded. RESULTS: A significant difference was noted between the visual acuities of the two eyes of the patients (2 lines or greater in the majority [64%] of patients). Nevertheless, for both eyes a significant correlation was noted between patient age and visual acuity, with older patients tending to have worse visual acuities. In the eyes with the best visual acuity, the majority of patients younger than 40 years of age (76%) had a visual acuity of 20/40 or better. In patients older than 30 years of age, a substantial percentage (74%) had a visual acuity of 20/100 or worse in at least one eye. CONCLUSION: The authors' findings indicate that although patients with Best vitelliform macular dystrophy who show characteristic macular lesions may retain good visual acuity in at least one eye, an appreciable number can lose substantial visual acuity, at least monocularly. In this population, no patient older than 50 years of age fulfilled the visual acuity criterion of 20/40 in at least one eye, the requirement in most states for an unrestricted driver's license, and only 20% of patients older than 40 years of age fulfilled this visual acuity criterion.

Adolescent↗

PubMed1991

Progression of visual acuity after penetrating keratoplasty.

A consecutive series of 721 eyes was followed for visual acuity changes after keratoplasty in four groups: keratoconus, Fuchs' dystrophy, pseudophakic bullous keratopathy with retained intraocular lenses, and aphakic/pseudophakic bullous keratopathy with secondary implants during keratoplasty. Follow-up ranged from 12 to 84 months. Keratoconus eyes showed the quickest recovery of visual acuity: by 12 months, 91% attained a best-corrected vision of 20/40, and the mean lines of visual acuity for the group plateaued thereafter. The other three groups showed continuing improvement in vision through 24 months. From 3 months through 3 years after keratoplasty, the keratoconus and Fuchs' groups consistently showed better visual acuity levels than either the retained or the secondary implant groups (P less than 0.0001). Reporting changes in visual acuity over time offers multiple advantages compared with providing best-attained or last-recorded visual acuities after keratoplasty.

Adolescent↗

PubMed1981

Prognosis of visual acuity after surgery for detached retina, with special reference to the unaffected eye.

In 600 patients with successfully operated unilateral retinal detachment, the visual acuity prognosis of the operated eye was studied in relation to that of the normal eye. Within 2 years after operation, most of these patients were in the following three groups: (1) visual acuity worse than 0.5 in the non-detached retina and worse than 0.1 in the reattached one; (2) visual acuity better than 1.0 in the non-detached retina and worse than 0.3 in the reattached one; and (3) visual acuity better than 1.0 in the non-detached retina and better than 0.8 in the reattached one. Some of the patients in group 2 showed greater improvement of the visual acuity in the reattached retina, which occasionally became superior to that in the non-detached one. In spite of possible improvement until 2 years after operation, the visual acuity in the reattached retina was apt to decrease after more than 5 years following operation. The presence of macular detachment was ill for the recovery of visual acuity. About 30% of the patients with a visual acuity of about 1.0 in the non-detached retina showed no improvement of the visual acuity in the reattached retina. About 50% of the patients with successful surgery for retinal detachment had a difference of more than 0.6 in visual acuity between the non-detached and the detached retinas.

Adult↗

PubMed1997

Effect of otolith dysfunction. Impairment of visual acuity during linear head motion in labyrinthine defective subjects.

Visual symptoms emerging after the loss of vestibular function are usually attributed to the dysfunction of semicircular canal vestibulo-ocular reflexes, as they have been shown to stabilize vision during angular head movements. However, natural head displacements involve both angular and linear motion, and therefore visual instability may occur because of defective otolith-ocular reflexes (OORs) which are the eye movements evoked by linear head acceleration. In this paper, the relationship between OORs and visual acuity during linear head motion was studied in normal subjects and 14 patients with bilateral loss of caloric responses. OORs were elicited in darkness by step acceleration (0.24 g) of the whole body along the interaural axis. Latency, slow phase velocity and asymmetry of the OOR were measured from the desaccaded and averaged electrooculographic trace. Visual acuity was assessed during sinusoidal lateral oscillation of the subject viewing an earth-fixed target, and vice versa with the subject stationary and the target moving at 0.5, 1.0 and 1.5 Hz. The task was to recognize numbers flashing up on a three digit light-emitting diode visual display. Normal subjects had symmetrical OORs with short latencies (< 130 ms). In patients, OORs were either absent (n = 2) or abnormal with asymmetries (n = 8), diminished velocities (n = 4) or prolonged latencies (n = 6). At high frequency oscillation (1.5 Hz), normal subjects invariably recognized more numbers during self-motion compared with target motion, whereas most patients did not. In patients, abnormal dynamic visual acuity was correlated with absent or delayed OOR responses. This is the first demonstration of a functional role of the OORs in that they contribute to visual stabilization during high frequency linear head motion. Bilateral vestibular failure commonly affects the OORs and thereby compromises dynamic visual acuity.

Acceleration↗

PubMed1991

A survey of the visual acuity of Brisbane drivers.

OBJECTIVE: To conduct a survey of the visual acuity of a group of Brisbane Drivers. SETTING: The outpatient department of the Princess Alexandra Hospital, Brisbane. PARTICIPANTS: Five hundred and three subjects drawn from patients, visitors and staff attending the outpatient department on 10 working days from December 5 to December 16, 1988. MAIN OUTCOME MEASURES: Subjects' age, driver's licence details and driving history were gathered by questionnaire. Visual acuity was assessed with the aid of a Snellen chart. RESULTS: Nearly 6% of the survey group had visual acuity worse than 6/12; 15% had never had their eyes tested other than for licensing purposes; 21% stated that their last ophthalmic or optometric examination was more than five years previously; and 8% failed to meet the Queensland visual acuity requirements for their class of licence. CONCLUSIONS: The monocular driver is not detected by current licence testing procedures in Queensland. Many licence holders do not meet the present visual acuity criteria of the Queensland Department of Transport.

Accidents, Traffic↗

PubMed2005

The association between visual acuity and central retinal thickness in retinitis pigmentosa.

PURPOSE: To determine whether visual acuity is related to central retinal thickness in patients with retinitis pigmentosa. METHODS: Visual acuities were measured with Early Treatment Diabetic Retinopathy Study (ETDRS) charts and optical coherence tomography (OCT3) was used to calculate retinal thicknesses and grade third high-reflectance bands in 162 patients with the typical forms of retinitis pigmentosa who had Snellen visual acuities of 20/20 to 20/200, minimal to no cataracts, and no visible macular cysts. Sixty-five patients were retested within 2 months to estimate the intervisit variability of retinal thickness measurements. RESULTS: ETDRS acuity was best related to retinal thickness measured at fixation and as the average value over the central 1 mm by a second-order polynomial (r(2) = 0.38 and P < 0.001 in both cases). Acuity was maximal for intermediate retinal thickness and appeared to decline for both lesser and greater retinal thicknesses. By linear regression, the decline in acuity for decreasing retinal thickness was steeper in eyes with an absent third high-reflectance band than for eyes with a partially distinct band. No decline was noted in eyes with an intact band. Assessment of intervisit variability of retinal thickness measurements showed 98% confidence limits of +/-17 microm at fixation and +/-11 microm for the central 1 mm. CONCLUSIONS: Both retinal thinning (due to cell loss) and retinal thickening (due to presumed edema) appear to be associated with lower visual acuity in patients with typical retinitis pigmentosa. The definition of the OCT third high-reflectance band may help to predict which patients are more likely to lose visual acuity as retinal thickness declines. An increase or decrease in retinal thickness of more than 17 microm at fixation or 11 microm over the central 1 mm at follow-up can be considered a significant (P < 0.01) change in these patients.

Adolescent↗