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Results for “Visual Acuity”

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PubMed1991

Opportunistic screening of visual acuity of elderly patients attending outpatient clinics.

A standard Snellen letter chart was used to screen the visual acuities of 202 elderly patients while they attended outpatients clinics. Patients overestimated the adequacy of their vision: only 34 patients reported inadequate vision while 72 had significant measured visual impairment. Of these, 30 patients had refractive errors and 42 primarily non-refractive problems. Thirty patients were examined by an ophthalmologist, of whom 24 had previously undiagnosed conditions. Eighteen patients had treatable conditions, predominantly cataracts and glaucoma. Ten patients with untreatable conditions had the benefit of a definitive diagnosis, most commonly of age-related macular degeneration, and an assessment of eligibility for registration of blindness. The routine assessment of elderly patients should include objective screening of their visual acuity.

Aged↗

PubMed2003

[A new objective visual acuity test: an automated preferential looking].

BACKGROUND: The Preferential Looking test using Teller acuity cards is widely used for preverbal children but has some weaknesses, in particular because it is examiner dependent and at best half-objective. We tested a new automated method in a pilot study. PATIENTS AND METHODS: In our preferential looking setting we project separate images into the left and right eye. This permits measuring each eye without having to cover the other. An infrared oculography system documents objectively and reproducibly whether or not the stimulus is seen. A square is shown which moves consecutively in a square formation on a background that has the same average brightness. Charting an XY-plot of the eye position results in a square with two diagonals, if the stimulus is seen. By using a specific baby examination unit, this test is already feasible in babies. In this study, the new setting was tested on two children. RESULTS: In two healthy children we found a good correlation between visual acuities determined with the new method and Teller visual acuity charts. Fogging one eye in each of the children resulted in fixation loss of the stimulus when the required visual acuity rose above the fogging value. CONCLUSIONS: This new technique permits one to perform an objective preferential looking test without the need of verbal answers. Larger studies have to validate these preliminary results.

Attention↗

PubMed1986

The effect of optical blur on visual acuity for targets of different luminances.

We studied the effect of 1.25 D of optical blur on visual acuity at luminances ranging from photopic to low mesopic levels. Optical blur reduces acuity at all luminances tested, this reduction being fourfold at a high photopic level (170 cd m-2) and twofold in low mesopia (0.017 cd m-2). The reduction of visual acuity with blur at low luminances is greater than might be expected from a spatial frequency analysis of vision.

Humans↗

PubMed2000

Environmental enrichment from birth enhances visual acuity but not place learning in mice.

The effect of richness of the environment on behavioral function was investigated in C57B6 mice. Animals were raised in either enriched (group-housed in large clear plexiglas cages with stimulating objects) or restricted (group housed in opaque white plastic cages with no stimulating objects) environmental conditions and their spatial learning and visual acuity were measured as adults. The performance of enriched and restricted groups were indistinguishable in place and cued versions of the Morris water task; however, the visual acuity of the enriched group, measured in a grating versus gray version of the visual water task, was 18% higher than the restricted group. These data demonstrate that the function of the mouse visual system can be significantly influenced by the nature of early visual input. They also indicate that the effects of environmental enrichment are manifested differently in behavioral measures of spatial learning and visual acuity.

Animals↗

PubMed1997

[Study on the effect of different disease courses on pre- and post-operative visual acuity in cases with congenital cataract].

OBJECTIVE: To study the effect of different disease courses on the visual acuity of congenital cataracts. METHOD: 876 cases with five kinds of human congenital cataract have been studied. RESULTS: It has been found that the preoperative visual acuity (VA) is closely related to the length of disease course. The longer the course of disease, the worse the VA. When the disease courses were shorter than one year, the most serious reduction of preoperative VA was found in the patients with congenital total cataract. When the disease courses were within one to four years, the most remarkable reduction of VA was found in patients with congenital dense nuclear cataract (CDNC). When the disease courses were longer than four years, except the congenital anterior polar cataract, the VA in all the other four kinds of cataracts were decreased significantly. It is indicated that the postoperative VA highly depends on the preoperative VA. In the group with disease courses shorter than one year, this relationship is the most remarkable. Some kinds of congenital cataract showed accelerated changes in preoperative VA, especially in the CDNC. CONCLUSION: It is suggested that the key point to get better visual function in cases with congenital cataract should be to discover and treat the patients as early as possible.

Adolescent↗

PubMed1999

Loss of visual acuity due to eye injuries among 6292 school children in the Sultanate of Oman.

PURPOSE: In 1992-94 a nation-wide survey in primary schools in the Sultanate of Oman for ocular disorders was conducted. This report focuses on the prevalence of visual acuity loss after injury. METHODS AND MATERIAL: A random selection of 6,292 children from Grades 1 and 6 from all primary schools in the country provided the research sample. Children who failed the visual acuity screening test received a complete "on the spot" eye examination by the pediatric ophthalmologist. RESULTS: 12 children were found to have monocular low vision (VA <0.3 to amaurosis) caused by injury. Total prevalence for loss of vision in one eye was 0.19%, with 0.15% in 6-year-olds and 0.25% in 12-year-olds Traumatic cataracts were noted in 4 children, 3 of these were in need of surgery. One child had aphakia after trauma surgery and needed a secondary lens implant. CONCLUSION: Altogether the prevalence of traumatic monocular visual damage in our study was 0.19%. Next to amblyopia, injury is the main reason for monocular loss of vision in childhood, however, both are preventable. Information about trauma prevention and the need for adequate ophthalmic care should be emphasized. Regular and repeated screening of visual acuity in children is essential.

Age Distribution↗

PubMedDate not supplied

[500 visual acuity tests in infants with Teller acuity cards].

Assessment of visual resolution with Teller Acuity Cards is now routine procedure in infant visual check-up. A grating is printed on one end of a card on an homogeneous background of the same mean luminance. A series of spatial frequencies at an interval of one half octave covers the range of infant acuity. Binocular and monocular acuities have been measured on 517 infants between 100 and 399 days of age. The cards can be used from a few weeks of age up to 18 months at least. Then it gets more chancy to keep the child attentive. Binocular and two monocular tests take 6 minutes with a normal child. Binocular grating acuity normally reaches 6.5 cycles/degree at 4 months of age, and 12 c/deg at 12 months. Monocular acuity is one half octave lower. From the level of acuity obtained and observation of the behaviour, amblyopia can be detected and low vision can be estimated easily in infants.

Equipment Design↗

PubMed1978

Enlarging optic chiasmal glioma with stable visual acuity.

A 13 1/2-year-old girl with stable, reduced visual acuity, nystagmus and Small, pale optic discs initially noted at age nine months, developed signs and symptoms of increased intracranial pressure. At craniotomy, an intrinsic glioma of the optic chiasm and both optic nerves extended into both frontal lobes, the hypothalamus and the third ventricle.

Adolescent↗

PubMed2001

Brain plasticity: 'visual' acuity of blind persons via the tongue.

The 'visual' acuity of blind persons perceiving information through a newly developed human-machine interface, with an array of electrical stimulators on the tongue, has been quantified using a standard Ophthalmological test (Snellen Tumbling E). Acuity without training averaged 20/860. This doubled with 9 h of training. The interface may lead to practical devices for persons with sensory loss such as blindness, and offers a means of exploring late brain plasticity.

Adult↗

PubMed1994

Influence of type and severity of pure forms of age-related cataract on visual acuity and contrast sensitivity. Italian American Cataract Study Group.

PURPOSE: To compare the relationship between logMAR visual acuity (VA) and cataract severity and between contrast sensitivity (CS) and cataract severity in pure types of age-related lens opacities. METHODS: Analysis included patients followed in the ongoing Italian-American Study of the Natural History of Age-Related Cataract. Lens opacities were classified and graded according to the Lens Opacities Classification System II (LOCS II). Visual acuity was measured with the Early Treatment Diabetic Retinopathy Study Chart. Contrast sensitivity was measured with the Pelli-Robson chart. RESULTS: Data from 1,076 eyes were used for the analysis (366 clear lenses; 550, 124, and 36 eyes with cortical, nuclear and posterior subcapsular cataract, respectively). In age-adjusted analyses, increasing severity of all three cataract types was associated with progressively higher logMAR VA, which translates into poorer acuity, and lower CS scores. For both VA and CS, the effect of increasing severity was greatest for nuclear and least for cortical opacities. After adjusting for age and VA, CS scores were no longer associated with cataract type and severity, with the exception of advanced cortical opacities. CONCLUSIONS: Increased cataract severity, as determined by LOCS II grading, is strongly associated with both VA and CS scores. Contrast sensitivity scores obtained from testing at low spatial frequency do not seem to offer additional information over standard VA testing in early cortical and posterior subcapsular opacities nor in nuclear cataracts.

Aged↗

PubMed1980

Visual acuity and binocularity in unilateral high myopia.

Thirty-eight patients with unilateral high myopia ranging from 5 to 19 diopters were followed up for a median of two years. All were treated with full-spectacle correction and most had occlusion. When initially examined one patient (3%) had visual acuity of 6/12 (20/40) or better, four patients (12%) had central fusion, and 24 patients (63%) were phoric. At the conclusion of the study 12 patients (32%) had visual acuities of 6/12 (20/40) or better, 17 patients (45%) had central fusion, and 29 patients (76%) were phoric. Age at the start of treatment was not a factor in the versely affect the response to amblyopia was inversely related to both final fusion and final visual acuity.

Adolescent↗

PubMed1989

Training effects on the resolution of moving targets--dynamic visual acuity.

In initial 60-min sessions, the dynamic visual acuity (DVA) of 54 male college observers was determined over a range of target velocities (60, 90, 120, and 150 deg/s) at each of three durations (200, 400, and 600 ms). Following four 30-min practice sessions with the task, a final test session identical to the first was then conducted. Highly significant training effects on DVA were obtained; contrary to previous work, these effects were most marked for observers with initially poorer performance.

Humans↗

PubMed1994

Arabic visual acuity chart for low vision examination.

An Arabic visual acuity chart has been designed for low vision examination, using ten Arabic letters constructed on a 5 x 5 framework. The chart contains seven pages with acuity values ranging from 20/600 to 20/80, corresponding to letter sizes of 26.5-3.5 cm. Interletter spaces were made one-fifth the size of each letter in a row while inter-row spaces were made equal to the height of the letters in the row below. The chart will be useful to eye care practitioners who may wish to use Arabic charts in low vision evaluation.

Adult↗

PubMed2002

Macular pigment and visual acuity in Stargardt macular dystrophy.

PURPOSE: To test the hypothesis that macular pigment reflects foveal cone function and possibly the presence of foveal cones in recessive Stargardt macular dystrophy. METHODS: Sixteen patients (32 eyes) diagnosed to have Stargardt macular dystrophy by clinical criteria were studied with a scanning laser ophthalmoscope (SLO) comparing argon laser blue (488 nm), green (514), helium-neon laser red (633 nm) and infrared diode laser (780 nm) images for the presence or absence of macular pigment in the fovea. Fifteen of the patients were screened for mutations in the ABCR gene. Eyes were graded into three categories: those without foveal macular pigment, those with partial pigment and those with normal amounts of macular pigment. These categories were compared with visual acuity determined by the Snellen chart. RESULTS: All patients with a visual acuity of 20/200 or worse had no macular pigment in the fovea. All patients with visual acuity of 20/40 or better had a normal amount of macular pigment in the fovea. Patients with partial macular pigment had intermediary acuity values except for two eyes, one with 20/20 and another with 20/200 acuity. Infrared light revealed more retinal abnormalities than blue light at early stages of the disease. CONCLUSION: Foveal macular pigment is related to foveal cone acuity in Stargardt macular dystrophy and may be a marker for the presence of foveal cones. Infrared light is a sensitive monitor of early Stargardt macular dystrophy.

Adolescent↗

PubMed1992

[5 years' experience in the treatment of neovascular glaucoma using cryocoagulation. II. Treatment of pain and the development of visual acuity].

The authors evaluate the therapeutic results of pain of the eyes and the development of visual acuity of 38 eyes with neovascular glaucoma treated by cryocoagulation. In 12 eyes they used cyclo-cryocoagulation as an independent method and in 26 eyes the method of transscleral panretinal cryocoagulation combined with cyclo-cryocoagulation. The authors did not find a correlation between the degree of increased intraocular pressure and the painfulness of the eye. In the treatment of pain they achieved markedly better results when using transscleral panretinal cryocoagulation than cyclo-cryocoagulation alone. The better therapeutic results of treatment of pain by combined cryosurgery is associated with a better compensation of intraocular pressure. In the authors' view a significant in the treatment of pain is also played by the newly described so-called analgetic effect of panretinal cryocoagulation which develops probably as a result of damage of sensitive nerves of the bulbus during freezing of the sclera and the choroid. The development of the so-called analgetic effect is probably associated with two facts: relief from severe pain was perceived also by patients where during the early postoperative period a high intraocular pressure still persisted and also in patients where a high intraocular pressure rose again. This condition was, however, as a rule not associated with the onset of new pain. The use of transscleral panretinal cryocoagulation combined with cyclo-cryocoagulation achieved regression of pain within 5 days after operation in 100%. The author provide evidence that the visual acuity in neovascular glaucoma recedes very rapidly and irreversibly.(ABSTRACT TRUNCATED AT 250 WORDS)

Cryosurgery↗

PubMed2003

[Value of Lotmar interferometry with vision assessment for predicting visual acuity after surgery of epimacular membranes].

BACKGROUND: To determine the usefulness of preoperative Lotmar interferometry to predict visual acuity recovery after surgery for epimacular membrane. PATIENTS AND METHODS: From 1999 to 2001, thirty pseudophakic eyes that underwent surgery for removal of epimacular membrane were examined prospectively. Visual acuity (VA) was recorded with the ETDRS chart before surgery and 6 months or more after (mean follow-up: 7.5 months). Lotmar interferometry was performed before surgery and its result was compared with the VA measured after surgery. RESULTS: The mean preoperative VA was 0.4 - 3 (20/55). The Lotmar VA (mean: 0.5, 20/40) was lower than the final postoperative VA (mean: 0.66, 20/30), p < 0.001. The Lotmar VA was found within one ETDRS line of the final postoperative VA in 10 cases (33 %). The Lotmar VA was > 1 line lower than the final postoperative VA in 17 cases (57 %) and was 1 - 3 lines higher in 3 cases (10 %). CONCLUSIONS: Lotmar interferometry tends to underestimate the final postoperative VA after surgery for epimacular membrane. A low value does not allow any relevant prediction. A high value is interesting since the risk to have a false-positive is low.

Aged↗

PubMed2006

Changes in visual acuity in a population over a 15-year period: the Beaver Dam Eye Study.

PURPOSE: To describe the change in visual acuity in a 15-year period. DESIGN: Population-based study. METHODS: setting: Beaver Dam, Wisconsin. participants: 4068 persons 43 to 86 years of age at the time of a baseline examination in 1988 to 1990, and with follow-up examinations every five years thereafter. observation procedures: Best-corrected visual acuity after refraction, assessed by a modification of the ETDRS protocol. main outcome measure: Doubling of the visual angle; incidence of visual impairment. RESULTS: Eight percent of the population developed impaired vision (20/40 or worse), 0.8% developed severe visual impairment (20/200 or worse), 7% had doubling of the visual angle, and 2% had improved vision. People 75 years of age or older at baseline were more likely to develop impaired vision (odds ratio [OR] 12.8, 95% confidence interval [CI] 9.6 to 17.1, P < .001), doubling of the visual angle (OR 7.8, 95% CI 5.6 to 10.7, P < .001), and severe visual impairment (OR 20.6, 95% CI 9.5 to 44.8, P<0.001) compared with people younger than 75 years of age. CONCLUSIONS: These data provide population-based estimates of the cumulative 15-year incidence of loss of vision over a wide spectrum of ages. In people 75 years of age or older the cumulative incidence of visual impairment accounting for the competing risk of death is 25%, of which 4% is severe, indicating a public health problem of considerable proportions as the US population in this age is expected to increase by 55% from 18 million in the year 2005 to 28 million by the year 2025.

Adult↗

PubMed2000

Phacoemulsification and intraocular lens placement in eyes with cataract and congenital coloboma: visual acuity and complications.

PURPOSE: To evaluate the safety and complications of phacoemulsification in a series of patients with congenital coloboma and cataract. SETTING: University-based hospital practice. METHODS: A retrospective review was conducted of consecutive patients who had coloboma and cataract and had phacoemulsification between January 1987 through December 1998. Complications and visual acuity 2 months postoperatively were assessed. RESULTS: Mean age of 7 cases at the time of surgery was 41.6 years +/- 11.1 (SD). Visual acuity improved in 6 of 7 eyes; 1 eye had no change. Six eyes had no serious complications. In 1 eye, a retinal detachment was observed postoperatively, but there was no loss in visual acuity. Another patient developed postoperative monocular diplopia from exposure of the intraocular lens (IOL) edge within the inferonasally located corectopia associated with the coloboma. Nonsurgical treatment was unsuccessful, but this symptom resolved after surgical pupilloplasty. CONCLUSIONS: The results of this small case series affirm that clinically significant cataract develops at a younger age in eyes with congenital coloboma than in eyes with typical age-related nuclear sclerotic cataract. Monocular diplopia, a potential complication after cataract surgery in these eyes, can be managed by pupilloplasty. The improved vision in this study indicates that phacoemulsification and IOL placement are safe and beneficial in patients with typical congenital coloboma and cataract.

Adolescent↗