Changes In Visual Ability Research Articles

Calibration of the Activity Inventory Item Bank: A Patient-Reported Outcome Measurement Instrument for Low Vision Rehabilitation.

PurposeTo provide calibrated item measures and rating category thresholds for the Activity Inventory (AI), an adaptive visual function questionnaire, from difficulty ratings obtained from a large sample of new low vision patients at pre-rehabilitation baseline.MethodsBaseline AI (510 items) rating scale data from five previous low vision rehabilitation outcome studies (n = 3623) were combined, and the method of successive dichotomizations was used to estimate calibrated item measures and rating category thresholds. Infit statistics were analyzed to evaluate the fit of the data to the model. Factor analysis was applied to person measures estimated from different subsets of items (e.g., functional domains such as reading, mobility) to evaluate differential person functioning.ResultsEstimated item measures were well targeted to the low vision patient population. The distribution of infit statistics confirmed the validity of the estimated measures and the two-factor structure previously observed for the AI.ConclusionsOur calibrated item measures and rating category thresholds enable researchers to estimate changes in visual ability from low vision rehabilitation on the same scale, facilitating comparisons between studies.Translational RelevanceThe work described in this paper provides calibrated item measures and rating category thresholds for a visual function questionnaire to measure patient-centered outcomes in low vision clinical research. The calibrated AI also can be used as a patient outcome measure and quality assurance tool in clinical practice.

Responsiveness of the Revised Low Vision Independence Measure (LVIM-R).

The Low Vision Independence Measure (LVIM) was designed to measure the effectiveness of occupational therapy to improve visual ability in low vision rehabilitation. To validate the Revised LVIM (LVIM-R) as an outcome measure by determining its sensitivity to visual ability changes after occupational therapy. In this observational study, LVIM-R scores were collected before and after customary low vision intervention. Home health agency or outpatient facility. Forty-four participants with a mean age of 80.2 yr (standard deviation = 11.2) and an average length of visual impairment of 6.2 yr. Twenty-three participants (52.3%) were treated in an outpatient setting, and 21 (47.7%) were treated in the home. The majority of participants were non-Hispanic White (92.8%) and had macular degeneration (54.5%). Customary low vision intervention by occupational therapists. LVIM-R scores were collected before and after intervention, and participants' pre- and posttest scores were anchored into Rasch-calibrated item parameters. Paired t tests demonstrated significant increases in person measures with large effect sizes for both constructs of the LVIM-R, the visual field or scotoma (t[43] = 6.46, p < .0001; Cohen's d = 0.92) and visual acuity (t[43] = 9.08, p < .0001; Cohen's d = 1.14) constructs. The LVIM-R is sensitive to changes in visual ability in clients who have good rehabilitation potential and can be used to examine the effectiveness of occupational therapy for low vision. The LVIM-R is useful for measuring occupational therapy outcomes in low vision rehabilitation in the home or in outpatient settings.

Veterans Affairs Low-vision Intervention Trial II: One-year Follow-up.

One-year follow-up is recommended for patients with macular diseases to assess functional changes associated with disease progression and to modify low-vision (LV) treatment plans, if indicated. The purpose of this study was to observe 255 patients with macular diseases who received LV rehabilitation (rehabilitation with a therapist) or basic LV services (LV devices dispensed without therapy) during Veterans Affairs Low-vision Intervention Trial II after the trial ended at 4 months until 1-year follow-up. The primary outcome measure was visual ability measured with the 48-item Veterans Affairs Low-vision Visual Functioning Questionnaire. Mean visual ability scores for the treatment groups were compared from baseline to 4 months, 4 months to 1 year, and baseline to 1 year. Changes from baseline to 1 year were compared between the two groups. Predictors of changes in visual ability from 4 months to 1 year were assessed using linear regression. Both groups experienced significant improvement in all measures of visual ability from baseline to 1 year but lost visual reading ability during the observation period (LV rehabilitation group, -0.64 [1.2] logit; 95% confidence interval [CI], -0.84 to -0.44 logit; basic LV group, -0.63 [1.4] logit; 95% CI, -0.88 to -0.38 logit), and overall visual ability was lost in the LV rehabilitation group (-0.20 [0.8] logit; 95% CI, -0.34 to -0.06 logit). Loss of visual reading ability in both groups from 4 months to 1 year was predicted by reading ability scores at 4 months, loss of near visual acuity from 4 months to 1 year, and lower EuroQol-5D utility index scores; loss of overall visual ability in the LV rehabilitation group during the same time period was predicted by lower overall ability scores at 4 months. Visual ability significantly improved in all groups from baseline to 1 year. However, the loss of visual reading ability experienced by both groups from 4 months to 1 year reduced the benefit of the services provided.

Visual and health outcomes, measured with the activity inventory and the EQ-5D, in visual impairment.

Generic instruments to assess health utilities can be used to express the burden of health problems in widely used indexes. That is in contrast with what can be obtained with condition-specific instruments, outcomes are very specific and difficult to compare across conditions. The purpose of this study was to assess health and visual outcomes and its determinants in patients with visual impairment (VI) using the EQ-5D-3L and the Activity Inventory (AI). Participants were recruited in different hospitals during the PCVIP-study. A total of 134 patients with acuity 0.30 logMAR or less in the better eye were interviewed. The AI includes 46 goals split between three objectives: social functioning, recreation and daily living, and was used to measure visual ability. The EQ-5D consists of five questions covering one domain each and was used to provide a measure of health states. Responses to each domain were combined to produce a single individual index. The AI and the EQ-5D-3L showed enough discriminatory power between VI levels (p<0.001), and their results were strongly correlated r(134)=0.825, (p<0.001). Explanatory factors for visual ability were level of VI in better eye, age and gender, R2 =0.43, (p<0.001). Explanatory factors for the EQ-5D-3L were level of VI in the better eye, comorbidities and gender, R2 =0.36, (p<0.001). Our results showed that the EQ-5D-3L is useful when characterizing the burden of VI and to compute, when necessary, quality-adjusted-life-years (QALY) changes due to VI. However, it is important to consider that the EQ-5D-3L uses a coarse response scale, assesses a limited spectrum of domains and is influenced by comorbidities. This might limit its responsiveness to small changes in visual ability.

Outcomes of the Veterans Affairs Low Vision Intervention Trial II (LOVIT II)

Randomized clinical trials are needed to compare effectiveness and cost-effectiveness of different low-vision (LV) programs. To determine the value of adding LV rehabilitation with a therapist compared with LV services without intervention. A randomized clinical trial was conducted from September 27, 2010, to July 31, 2014, of 323 veterans with macular diseases and best-corrected distance visual acuity (BCDVAbetter-eye) of 20/50 to 20/200. Masked interviewers administered questionnaires by telephone before and after LV treatment. Using an intention-to-treat design, participants were randomized to receive LV devices with no therapy or LV devices with a rehabilitation therapist providing instruction and homework on the use of LV devices, eccentric viewing, and environmental modification. Visual ability was measured in dimensionless log odds units (logits) (0.14-logit change in visual ability corresponds to ability change expected from a 1-line change in visual acuity). Low-vision devices without therapy and LV devices with therapy. Comparison of changes (baseline to 4 months) in overall visual ability and in 4 functional domains (reading, visual information, visual motor, and mobility) estimated from responses to the Veterans Affairs Low Vision Visual Functioning Questionnaire (higher scores indicates more ability or less difficulty in performing activities), and comparison of MNREAD changes (baseline to end of treatment) in maximum reading speed, critical print size, and reading acuity (higher number indicates lower visual acuity). Of the 323 participants, 314 were male (97.2%); mean (SD) age, 80 (10.5) years. Basic LV was effective in improving visual ability. However, the LV rehabilitation group improved more in all visual function domains except mobility. Differences were 0.34-logit reading (95% CI, 0.0005 to 0.69; P = .05), 0.27-logit visual information (95% CI, 0.01 to 0.53; P = .04), 0.37-logit visual motor (95% CI, 0.08 to 0.66; P = .01), and 0.27-logit overall (95% CI, 0.06 to 0.49; P = .01). For MNREAD measures, there was more improvement in reading acuity (difference, -0.11 logMAR, 95% CI, -0.15 to -0.07; P < .001) and maximum reading speed (mean increase of 21.0 words/min; 95% CI, 6.4 to 35.5; P = .005), but not critical print size for the LV rehabilitation group (-0.06 logMAR; 95% CI, -0.12 to 0.002; P = .06). In stratified analyses, the LV rehabilitation group with BCDVAbetter-eye worse than 20/63 to 20/200 improved more in visual ability (reading, visual motor, and overall). Differences were 0.56-logit reading ability (95% CI, 0.08-1.04; P = .02), 0.40-logit visual motor (95% CI, 0.03-0.78; P = .04), 0.34-logit overall (95% CI, 0.06-0.62; P = .02). There was no significant difference between treatment groups for those with BCDVAbetter-eye of 20/50 to 20/63. Both basic LV alone and combined with LV rehabilitation were effective, but the added LV rehabilitation increased the effect only for patients with BCDVAbetter-eye worse than 20/63 to 20/200. Basic LV services may be sufficient for most LV patients with mild visual impairment. clinicaltrials.gov Identifier: NCT00958360.

Validation of an instrument to assess visual ability in children with visual impairment in China

ObjectiveTo validate a visual ability instrument for school-aged children with visual impairment in China by translating, culturally adopting and Rasch scaling the Cardiff Visual Ability Questionnaire for Children (CVAQC).MethodsThe 25-item...

The Effectiveness of Low-Vision Rehabilitation in 2 Cohorts Derived From the Veterans Affairs Low-Vision Intervention Trial

To evaluate the effectiveness of low-vision rehabilitation in 2 cohorts derived from the Veterans Affairs Low-Vision Intervention Trial. In a prospective study, we observed 44 participants randomly assigned to outpatient low-vision rehabilitation who did not receive additional treatment after the trial ended at 4-month follow-up and 56 participants randomly assigned to the waiting-list control group and thereafter to standard therapy. The outcome measures included visual ability domains (reading, mobility, visual information processing, and visual motor skills) and overall visual ability estimated from difficulty ratings using the 48-item Veterans Affairs Low-Vision Visual Functioning Questionnaire. Mean visual ability scores for the treatment and control groups were compared at baseline, 4 months, and 1 year. A mixed-effects model was used to test treatment effects between groups over time. Differences in visual ability mean scores from baseline to 1 year were compared between the 2 groups. Within-group changes in visual ability were compared from baseline to 1 year, from baseline to 4 months, and from 4 months to 1 year. At baseline, there were no significant differences in mean visual ability scores between groups. From baseline to 4 months, the treatment effects for all visual ability domains and overall visual ability increased to a maximum in the treatment group (P< .001), whereas the mean scores (except visual motor skills) decreased in the control group (P< .01). From 4 months to 1 year, the differences became smaller. There was a loss of visual ability in reading and visual information processing (but not in visual motor skills, mobility, or overall visual ability) in the treatment group and a gain in all visual ability measures in the control group. Interactions of treatment and follow-up time in the mixed models showed the trend of treatment effects significantly changed over time from baseline to 1 year (P< .001) for all visual ability domains and overall visual ability. Both groups demonstrated improvement in visual ability from baseline to 1 year (P< .001) (except for mobility in the control group). Overall visual ability (but not other visual ability domains) improved more in the treatment group than in the control group (P= .01). Visual ability improved significantly in both groups from baseline to 1 year. The Low-Vision Intervention Trial treatment effect is robust and well maintained for patients with macular diseases.

The effect of low vision rehabilitation in diabetic eye disease: a randomised controlled trial protocol

Current research highlights a rising incidence of diabetes and its complications. Diabetic retinopathy is the leading cause of blindness within the working-age population of the United Kingdom. Increasing severity of retinopathy is associated with reduced visual function and participation in daily living. Only 8% of those referred to Moorfields Eye Hospital's low vision clinic have diabetic eye disease, a value less than prevalence figures for diabetes would predict. The lack of evidence for effectiveness of low vision intervention in this patient group could be responsible. Therefore, in line with CONSORT guidance, we present the methodology of the first randomised controlled trial to quantify the effect of low vision rehabilitation on people with diabetic eye disease. One hundred participants were recruited into four retinopathy severity groups based on their diagnosis according to the English National Screening Programme Grading Protocol. Participants were randomised to either immediate intervention (1-2 weeks after enrollment) or delayed (control) intervention (3 months after enrollment). Intervention was a standard low vision assessment performed in a hospital clinic. The Activity Inventory (AI), was administered to all participants by telephone within 1 week of enrollment (before any intervention) and repeated at 3 and 6 months. One hundred participants (Type 1: 28, Type 2: 72; male: 62, female 38) have been recruited. Median habitual distance acuity was 0.19 logMAR (6/9, 20/30), with an interquartile range of 0.06-0.30 logMAR (6/7.5-6/12, 20/25-20/40). AI responses were scored by Rasch analysis, providing a measure of visual ability. Median baseline visual ability was 1.64 logits, with an interquartile range of 0.60-3.75 logits. Difference in mean change in visual ability between intervention groups will be assessed 3 months (primary outcome) and 6 months (secondary outcome) after enrollment. This is the first randomised controlled trial investigating the effectiveness of low vision rehabilitation for people with diabetic eye disease. With recruitment already complete, it is hoped this work will be the first step in guiding referral criteria for those with diabetic eye disease into the low vision service.

Eye growth in sharks: Ecological implications for changes in retinal topography and visual resolution

The visual abilities of sharks show substantial interspecific variability. In addition, sharks may change their habitat and feeding strategy throughout life. As the eyes of sharks continue to grow throughout the animal's lifetime, ontogenetic variability in visual ability may also occur. The topographic analysis of the photoreceptor and ganglion cell distributions can identify visual specializations and assess changes in visual abilities that may occur concurrently with eye growth. This study examines an ontogenetic series of whole-mounted retinas in two elasmobranch species, the sandbar shark, Carcharhinus plumbeus, and the shortspine spurdog, Squalus mitsukurii, to identify regional specializations mediating zones for improved spatial resolution. The study examines retinal morphology and presents data on summation ratios between photoreceptor and ganglion cell layers, anatomically determined peak spatial resolving power, and the angular extent of the visual field. Peak densities of photoreceptors and ganglion cells occur in similar retinal locations. The topographic distribution of neurons in the ganglion cell layer does not differ substantially with eye growth. However, predicted peak spatial resolution increases with eye growth from 4.3 to 8.9 cycles/deg in C. plumbeus and from 5.7 to 7.2 cycles/deg in S. mitsukurii. The topographic distribution of different-sized ganglion cells is also mapped in C. plumbeus, and a population of large ganglion cells (soma area 120-350 microm2) form a narrow horizontal streak across the retinal meridian, while the spatial distribution of ordinary-sized ganglion cells (soma area 30-120 microm2) forms an area in the central retina. Species-specific retinal specializations highlight differences in visually mediated behaviors and foraging strategies between C. plumbeus and S. mitsukurii.

The Veterans Affairs Low Vision Intervention Trial (LOVIT): Design and Methodology

Visual impairment is a major public health problem. Vision rehabilitation programs have the potential to restore independence and improve quality of life for persons with permanent vision loss, and few have been evaluated in randomized controlled trials. The Veterans Affairs (VA) Low Vision Intervention Trial is a multicenter randomized clinical trial to evaluate the effectiveness of a new outpatient low vision rehabilitation program. 126 patients with moderate and severe vision loss due to macular diseases are randomized to low vision treatment in an outpatient setting or a usual care control group at two VA facilities in Hines, Illinois, and Salisbury, North Carolina. The primary outcome is the change in visual reading ability from baseline to four months measured with the Veterans Affairs Low Vision Visual Functioning Questionnaire-48 (VA LV VFQ-48). Secondary outcomes compare the mean change in visual ability measured with the VA LV VFQ-48 (overall ability, mobility, visual information processing, visual motor skills) for the treatment and control groups. Costs and cost effectiveness of outpatient treatment are evaluated. The low vision rehabilitation setting, use of a waiting list control group to address ethical issues, development of the treatment protocol, development of a vision function questionnaire for patients to self-report the difficulty they experience performing daily activities, and the use of Rasch analysis to develop and estimate this outcome measure are described. If the new low vision rehabilitation program is proven effective, studies will be needed to determine which of the multiple aspects of the intervention are necessary and sufficient. The challenges of conducting clinical trials in a rehabilitation setting and use of a waiting list (deferred treatment) control group extend beyond LOVIT. The design and methods of LOVIT may be applicable to other trials of rehabilitation services and to outcomes for which reliable and valid measurement tools must be developed.

Interactive Factors in the Reading Rehabilitation of Elderly Persons with Low Vision in Sweden

This study of the interaction between some background variables and visual deficits in the reading training of elderly participants with low vision found that differences between the participants in a three-year period did not seem to be related primarily to changes in visual ability. Rather, other factors, especially aging and all its consequences, were more influential in maintaining reading ability.

Dissatisfaction with cataract surgery in relation to visual results in a population-based study in Sweden

Purpose To evaluate dissatisfied patients and those with subjectively worse visual ability after cataract surgery and to analyze how these factors relate to poor visual acuity results (worse than 20/40). Setting Department of Ophthalmology, Norrlands University Hospital, Umeå, Sweden. Methods A prospective, population-based study of cataract surgery outcome was conducted. All patients (459 surgeries) who had cataract surgery during a 1 year period were studied using self-administered questionnaires and data from patient records. Outcome measures were (1) patient degree of satisfaction with the result, (2) subjective visual ability after surgery of visually demanding tasks such as reading, television viewing, orientation in unfamiliar surroundings, and distance estimation far and near, and (3) visual acuity results. Results After surgery, 37 of the 459 cases (8%) were dissatisfied. These patients had a significantly lower age-corrected visual acuity in the operated eye than the satisfied patients ( P < .0001). Ten percent said 1 or more visual ability was worse after their cataract surgery. Logistic regression analysis revealed that the visual acuity in the better eye before surgery and age-related maculopathy were the most significant risk factors. Poor visual acuity after surgery in the operated eye was found in 22%, mostly as a result of concurrent age-related maculopathy, diabetes, or glaucoma. Four percent had no improvement in visual acuity in the operated eye. Conclusions Dissatisfaction seemed to rely mostly on visual acuity in the operated eye. Low visual acuity in the better eye before surgery and age-related maculopathy were the most significant risk factors for subjectively worse visual ability after surgery. The degree of satisfaction after cataract surgery and changes in visual ability differed in important ways from visual acuity as a measure of visual function.

The Acuity Card Procedure: Longitudinal Assessments

Traditional methods of visual assessment in preverbal pediatric patients rely on refined but subjective measurement techniques. A standard ophthalmologic examination includes evaluation of a child's fixation patterns, with performance ranked on the basis of ability to fix and follow an object (F & F) or maintain central, steady fixation (CSM). In the hands of a skilled clinician, these evaluations are important for diagnosis and treatment. Documentation of quantitative changes in visual abilities of preverbal patients, however, has only recently become feasible. We began using the acuity card procedure in our pediatric clinical practice more than 3 years ago. This assessment, a modified version of the standard Forced-Choice Preferential Looking paradigm (FPL), provides quantitative evaluation of visual functioning in preverbal patients. The total number of patients assessed on one or more occasions exceeds 900. Of this group, we followed 83 patients with at least four acuity card evaluations on separate visits. Thirty of these patients, all with different diseases, have been evaluated with acuity cards on six or more visits. We found the information provided by the acuity card assessments extremely helpful in quantifying the developmental and therapeutic changes in vision, previously monitored only qualitatively.

Older Drivers' Visibility and Comfort in Night Driving: Vehicle Design Factors

Older persons are a growing proportion in the population, among drivers and those involved in traffic accidents. Changes in visual abilities of older persons are pertinent to night driving in which they need greater brightness contrast to see and minimum glare. Vehicle headlighting and related factors are reviewed which affect visibility and comfort in night driving. Older drivers, in particular, would be aided at night by: increasing the reflectivity of objects, limiting the mounting height of headlamps, appropriate reflectivities of mirrors for control of glare, automatic headlamp alignment, automatic headlamp cleaning and beam patterns that emphasize glare control.