Reduced visual acuity in elderly people: the role of ergonomics and gerontechnology

Branch pulmonary artery stenosis is a common problem in pediatric cardiology. Treatment has included surgery, balloon angioplasty, and balloon expandable stent placement. It was the purpose of this investigation to demonstrate the cost-effectiveness of each of these modes of treatment. From 1983 to 1994 there were 30 patients admitted for treatment of branch pulmonary artery stenosis only. Data included age at procedure, sex, primary diagnosis, acute and intermediate term success, and complications. Acute success was defined by results at the end of the procedure where intermediate term (IT) success was defined by results at follow-up. Success of a procedure was defined by at least one of the following: an increase in vessel diameter by >/=50% of predilation diameter, a decrease in right ventricular to left ventricular or aortic systolic pressure ratio by >/=20%, or a decrease in peak to peak pressure gradient by >/=50%. The procedure was considered a failure if the previously mentioned criteria were not met or if the patient required a second procedure for the same stenosis. The expense of the procedure (estimated by using the patient charges) were collected from the time of the procedure until December 1994. Because of differing lengths of follow-up, the patients were analyzed separately for procedures and outpatient charges. The total charges were corrected to 1994 dollars using the Medical Consumer Price Index. Thirty patients had 46 separate procedures (12 patients had >1 procedure and 3 had >2 procedures). There were 13 surgeries, 13 balloon angioplasties, and 20 stents. Stents were the most successful (90% acute and 85% IT), but were not statistically superior to surgery (62% acute and IT). Balloon angioplasty was significantly less successful as compared with stents (31% acute and 23% IT), and was not statistically different from surgery over the acute and intermediate term. The charge data showed balloon angioplasty was the least expensive followed by stents and then by surgery. The average total charges per procedure, including outpatient charges, were: surgery $58,068 +/- $4372 (standard error), balloon $21,893 +/- $5019, stents $33,809 +/- $3533 (p < 0.001); excluding outpatient charges: surgery $52,989 +/- $3649, balloon $15,653 +/- $1691, and stents $29,531 +/- $2241 (p < 0.001). Average total charges per patient, including all procedure types and grouped by initial procedure, were: surgery $53,707 +/- $6388, balloon $50,040 +/- $8412, and stent $34,346 +/- $3488 (p = 0.047). Stents were at least as effective as surgery and were more effective than balloon angioplasty in both acute and intermediate term follow-up. Balloon angioplasty was least expensive per procedure but was also least effective. Therefore, intravascular balloon expandable stents are the most cost-effective means available in the treatment of branch pulmonary artery stenosis.     

Table for assessing visual acuity in children]

The effect of vegetable (peach kernel) oil on the somatic development and puberty of female rats was studied. The oil was injected (0.2 ml) once intramuscularly into the prepuberty (aged 35 days) or (at the age of 31-35 days) five times. The oil inhibited dose-dependently the somatic development of the rats before puberty. It inhibited the ovarian endocrine function, significantly delayed the initial (opening of the vagina) and terminal (ovulation) stages of puberty or suppressed it completely (in 30% of cases).     

Psychophysics of reading--XVI. The visual span in normal and low vision

The visual span in reading is the number of characters that can be recognized at a glance. The shrinking visual span hypothesis attributes reading deficits in low vision, and slow reading in normal vision at low contrast, to a reduction in the visual span. This hypothesis predicts that reading time (msec/word) becomes increasingly dependent on word length as text contrast decreases. We tested and confirmed this prediction using the rapid serial visual presentation (RSVP) method. Estimates of the visual span ranged from about 10 characters for high-contrast text to less than two characters for low-contrast text. Eye-movement recordings showed that longer reading times at low contrast are partitioned about equally between prolonged fixation times and an increased number of saccades (presumably related to a reduced visual span). RSVP measurements for six out of seven low-vision subjects revealed a strong dependence of reading time on word length, as expected from reduced visual spans.     

Acyclovir treatment--its effect on visual acuity and the rate of recurrences in herpetic keratitis]

We treated a number of 141 patients suffering of herpetic keratitis--34 were treated with Acyclovir in the first 72 hours the symptoms started, 42 were treated with Acyclovir after this interval and 65 were treated with IDU. We compared visual acuity after six month and we proved that those that were treated with Acyclovir had the same or better visual performances in most cases. Recurrence rate was 0% in the first year and 2.94% in the second year for those witch were treated with Acyclovir in the first 72 hours symptoms started and 2.94% in the first year and 14.71% in the second year for those treated with Acyclovir after this interval. Patients treated with IDU had suffered 23.53% recurrences in the first year and 41.18% recurrences in the second year. Acyclovir treatment and its precociousness protect patients sight and reduce number of recurrences.     

Assessment of high and low contrast visual acuity after photorefractive keratectomy for myopia

BACKGROUND: Our aim was to assess visual acuity using standardized charts and illumination conditions after photorefractive keratectomy. METHODS: High and low contrast visual acuity were measured on Bailey-Lovie logarithm of the minimum angle of resolution (LogMAR) charts under high and low illumination conditions on 105 photorefractive keratectomy patients who had been treated with the Summit (N = 60) or the VISX (N = 45) excimer laser. RESULTS: Best corrected visual acuity was reduced in the treated eye compared with the untreated control eye under all test conditions, with the greatest differences under conditions of low contrast and low illumination. Reduction of acuity under low contrast and low illumination was related to small optic zone sizes and steep ablation edge profiles found in Summit-treated eyes. In the VISX-treated eyes, high contrast acuity was reduced in the presence of central topographical irregularities, subepithelial haze, and higher myopic corrections. CONCLUSIONS: Testing conditions such as those described here may be useful in quantifying vision degradation in suboptimal viewing conditions and among patients with vague complaints.     

The study on changes of macular light sensitivity before and after photocoagulation for diabetic macular edema

OBJECTIVE: The study was designed to determine whether laser photocoagulation could damage macular visual function in treatment of diabetic macular edema. METHODS: A prospective clinical trial was taken to determine the effects of argon green (514.5nm) laser photocoagulation on macular light sensitivity (MLS) by comparing the self MLS pairing data collected from a Humphrey automatic visual field analyzer before and after the procedure. Nineteen eyes of 15 patients with diabetic macular edema consistent with its diagnostic criteria were enrolled in this study, a follow-up period being 3 months. RESULTS: The mean MLS at the photocoagulation area, non-photocoagulation area, 5 degrees and 13 degrees eccentricity were significantly decreased within 1 week after the treatment, the drops of MLS were 1.85 dB, 1.05 dB, 0.99 dB, 1.66 dB respectively (P < 0.05). The mean reduction of MLS at the fovea within 1 week after the treatment has no statistical significance. The MLS gradually recovered at the 1st and 3rd month after photocoagulation, and the visual acuities in most of the cases were stable or increased. CONCLUSIONS: MLS is affected little by laser photocoagulation, and photocoagulation can reduce the risk of visual loss or increase visual acuity in an eye with diabetic macular edema.     

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.     

The visual acuity for the lateral visual field of the pigeon (Columba livia)

Previous studies on pigeons indicated that the visual acuity for the frontal visual field was much higher than that for the lateral one. Suspecting that the poor values for the lateral field were due to suboptimal testing conditions, we determined the lateral field acuity in eight head-fixed pigeons with high-contrast square-wave gratings. An instrumental conditioning task with water as reinforcer and mandibulation as an operant was used. Subjects achieved a mean acuity value of 12.6 c/deg. The results show that the acuity of the lateral visual field is only slightly lower than that of the frontal field. These data provide a psychophysical basis for ecological observations that pigeons and most other birds gaze laterally when scrutinizing small and distant objects.     

The nature and basis of age-related changes in dynamic visual acuity.

The ability of observers to resolve moving targets, or dynamic visual acuity (DVA), was determined for a group of young adults (M age?=?19.6 years) and a group of older adults (M age?=?67.6 years). Targets were presented at two luminance levels over a range of velocities (30, 60, 90, and 120 deg/s) and at 2 durations (200 and 600 ms). The younger subjects exhibited superior DVA under nearly all conditions, but this effect was essentially eliminated by the luminance adjustment. These results are interpreted in terms of decreased retinal illumination in the older subjects rather than in terms of age-related changes in the underlying eye movement systems. Practical and theoretical implications are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The relationship between corneal eccentricity and improvement in visual acuity with orthokeratology

BACKGROUND: Due to the renewed attention given to reduction of myopia, interest in orthokeratology has dramatically increased. This study was performed to determine whether or not a predictor for orthokeratologic changes can be identified. METHODS: Fifteen subjects enrolled in the study. For each subject, corneal eccentricity (e) was measured, subjective refraction and autorefraction were performed, and intraocular pressures were taken. Each subject was then fitted with a rigid contact lens for orthokeratology and followed for a minimum of 16 weeks. Eleven subjects completed the study. RESULTS: No correlation between corneal eccentricity and improvement in visual acuity was found. Correlations were found between e and changes in subjective refraction, and between e and changes in autorefraction. There was also correlation between lower intraocular pressure and changes in subjective refraction, and between lower intraocular pressure and changes in autorefraction. CONCLUSIONS: These findings suggest that corneal eccentricity and lower intraocular pressures may be predictors of orthokeratologic changes. A longitudinal study with a larger subject size will be needed to conclusively determine if these two measurements are predictors of orthokeratologic changes.     

Effect of levodopa therapy on visual evoked potentials and visual acuity in amblyopia

Between 10 and 11 years after children were vaccinated with Vi capsular polysaccharide of Salmonella typhi or meningococcal A + C control vaccine in a double blind randomized trial, we traced 83 subjects, aged 16-20 years. A blood sample was taken for determination of Vi antibody titres in both groups by radioimmunoassay. TO and TH titres were also done to assess if the participants had had recent exposure to typhoid fever. Fifty-eight percent of subjects in both groups had protective levels of Vi antibody against Salmonella typhi (a titre greater than 1 microgram ml-1). There was no significant difference in the levels of Vi antibodies in the cases versus the controls (p = 0.5). Two of the children who had received meningococcal A + C vaccine had recently had typhoid fever. Our data show that adolescents in typhoid endemic areas have high levels of Vi antibodies regardless of previous vaccination status, suggesting that Vi antibodies are acquired in adolescence by a large percentage of the population in this area. Moreover, Vi vaccination has led to ongoing antibody production in greater than 50% of Vi vaccinated children in an endemic area for a period of 10 years. Ongoing antigenic exposure may have contributed to these antibody levels.     

Computerized dynamic visual acuity test in the assessment of vestibular deficits

Hypoglossal facial anastomosis (HFA) is a standard surgical technique for restoration of facial movements in cases of intratemporal lesions of the facial nerve. Case reports provide evidence that an affected trigeminal system reduces functional outcome. In order to detect morphological changes in the hypoglossal nucleus responsible for this phenomenon, we used 18 Wistar rats and performed three different surgical combinations. In group 1, six animals received HFA only. In group 2, HFA was combined with resection of the contralateral infraorbital nerve. In group 3, HFA was combined with resection of the ipsilateral infraorbital nerve. Fifty-six days after the operation, horseradish peroxidase (HRP) was injected into the whisker pad. As shown in previous studies using HRP, retrograde-labelled motoneurons occurred in the hypoglossal and facial nuclei. Counts of the labelled motoneurons showed no change in the number of projecting hypoglossal motoneurons in group 2 when compared to HFA only, but a significantly smaller number in group 3 (-35%). Furthermore, the number of projecting facial motoneurons was significantly reduced in group 2 (-85%) and group 3 (-45%). These morphological findings indicate an absent or insufficient functional connection between the contralateral infraorbital nerve and the hypoglossal nucleus, and a strong influence of the infraorbital nerve to the ipsi- and contralateral facial nuclei. Additionally, our study provides morphological evidence that the integrity of the sensory trigeminal system is very important in reconstructive facial nerve surgery.     

Theories of visual acuity and their physiological bases.

An orientation into the problem of visual acuity and of the size and distribution of retinal receptors precedes a discussion of the principal theories of visual acuity. The 2 static theories covered are Hartridge's and Hecht's, including a critique of Hetcht's theory where evidence is cited that fails to support his position. The 2 dynamic theories discussed are those of Weymouth and his colleagues, and of Marshall and Talbot. The Marshall-Talbot theory, accounting for visual phenomena other than acuity alone, is viewed as the best existing theory, and is evaluated in terms of the principal physiological mechanisms on which the theory is based. 84 references. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A comparative study on the influence of dopamine and metaproterenol on the ventricular fibrillation threshold in cats

The influence of 3-4-dihydroxyphenylethylamine (dopamine) on the VFT of the cat heart was checked with different doses in comparison to metaproterenol (Alupent). In the therapeutical doses dopamine has no significant influence on the VFT in contrast to metaproterenol. The clinical relevance of our findings seems to be that dopamine can be applied in therapeutical doses without running the risk of inducing serious cardiac arrhythmia.     

Changes in visual acuity in a population. The Beaver Dam Eye Study

PURPOSE: To describe the change in visual acuity over a 5-year period in persons participating in a large population-based study. METHODS: Best-corrected visual acuity was measured, after refraction, with logMAR charts using a modification of the Early Treatment Diabetic Retinopathy Study protocol in 3684 persons living in Beaver Dam, Wisconsin, who ranged in age from 43 to 86 years at the time of a baseline examination from 1988 to 1990, and at a follow-up examination from 1993 to 1995. RESULTS: The change in the number of letters read correctly over the 5-year period varied from 0.4 +/- 4.9 (mean +/- standard deviation) in people between 43 and 54 years of age to -5.2 +/- 15.4 in people 75 years of age or older at baseline. Over the 5-year period, vision became impaired (20/40 or worse in the better eye) in 2.9% of the population and severely impaired (20/200 or worse in the better eye) in 0.3%. The visual angle doubled in 1.7% of the population, and 2.4% had improved vision. People 75 years of age or older at baseline were 12.5 times (95% confidence interval [Cl], 8.6-18.2; P < 0.001) more likely to have impaired vision, 9.7 times (95% Cl, 5.9-16.0; P < 0.001) more likely to have doubling of the visual angle, and 78 times more likely (95% Cl, 9.9-614.1; P < 0.001) to have severe visual impairment than people younger than 75 years of age at baseline. People 75 years of age or older who were living in nursing homes or group homes were 3.8 times more likely to have impaired vision, 3.3 times more likely to have severely impaired vision, and 5.7 times more likely to have a doubling of the visual angle than those not residing in a nursing home or a group home. CONCLUSION: These data provide precise population-based estimates of incidence of visual loss over a wide spectrum of ages and show that decreased visual acuity in people 75 years of age is a common finding, especially in those who are in nursing homes or group homes.     

Spatial frequency and light-spread descriptions of visual acuity and hyperacuity

Resolution (visual acuity) and differential spatial localization (hyperacuity) targets were selected to allow rigorous psychophysical measurements as well as ready expression of both their spatial frequency spectrum and their retinal image light distribution. Thresholds were about 1 arc min for acuity and 4-6 arc sec for hyperacuity. As is consistent with the reciprocal relationship between the space and spatial frequency domains, the small locally restricted spatial differences between just distinguishable patterns are represented in the frequency domain by equally small differences, which are distributed over the entire spatial frequency spectrum. While they occur in many test situations, phase variations of spatial frequency components are not necessary for achieving optimum acuity and hyperacuity.