Is the NEI-VFQ-25 a useful tool in identifying visual impairment in an elderly population?

BACKGROUND: The use of self-report questionnaires to substitute for visual acuity measurement has been limited. We examined the association between visual impairment and self reported visual function in a population sample of older people in the UK. METHODS: Cross sectional study of people aged more than 75 years who initially participated in a trial of health screening. The association between 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ) scores and visual impairment (defined as an acuity of less than 6/18 in the better eye) was examined using logistic regression. RESULTS: Visual acuity and NEI-VFQ scores were obtained from 1807 participants (aged 77 to 101 years, 36% male), from 20 general practices throughout the UK. After adjustment for age, gender, practice and NEI-VFQ sub-scale scores, those complaining of poor vision in general were 4.77 times (95% CI 3.03 to 7.53) more likely to be visually impaired compared to those who did not report difficulty. Self-reported limitations with social functioning and dependency on others due to poor vision were also associated with visual impairment (odds ratios, 2.52, 95% CI 1.55 to 4.11; 1.73, 95% CI 1.05 to 2.86 respectively). Those reporting difficulties with near vision and colour vision were more likely to be visually impaired (odds ratios, 2.32, 95% CI 1.30 to 4.15; 2.25, 95% CI 1.35 to 3.73 respectively). Other NEI-VFQ sub-scale scores were unrelated to measures of acuity. Similar but weaker odds ratios were found with reduced visual acuity (defined as less than 6/12 in the better eye). Although differences in NEI-VFQ scores were small, scores were strongly associated with visual acuity, binocular status, and difference in acuity between eyes. CONCLUSION: NEI-VFQ questions regarding the quality of general vision, social functioning, visual dependency, near vision and colour vision are strongly and independently associated with an objective measure of visual impairment in an elderly population

Patient-centred measurement in ophthalmology – a paradigm shift

Ophthalmologists and researchers in ophthalmology understand what a rapidly evolving field ophthalmology is, and that to conduct good research it is essential to use the latest and best methods. In outcomes research, one modern initiative has been to conduct holistic measurement of outcomes inclusive of the patient's point of view; patient-centred outcome. This, of course, means including a questionnaire. However, the irony of trying to improve outcomes research by being inclusive of many measures is that the researcher may not be expert in all measures used. Certainly, few people conducting outcomes research in ophthalmology would claim to be questionnaire experts. Most tend to be experts in their ophthalmic subspecialty and probably simply choose a popular questionnaire that appears to fit their needs and think little more about it. Perhaps, unlike our own field, we assume that the field of questionnaire research is relatively stable. This is far from the case. The measurement of patient-centred outcomes with questionnaires is a rapidly evolving field. Indeed, over the last few years a paradigm shift has occurred in patient-centred measurement

Lutein supplementation in retinitis pigmentosa: PC-based vision assessment in a randomized double-masked placebo-controlled clinical trial [NCT00029289]

BACKGROUND: There is no generally accepted medical or surgical treatment to stop the progressive course of retinitis pigmentosa. Previous studies have suggested lutein as a potential treatment with positive effects on macular pigment density. The objective of this study was to examine the effect of lutein supplementation on preservation of visual function in patients with retinitis pigmentosa (RP) METHODS: In a double-masked randomized placebo-controlled phase I/II clinical trial with a cross-over design, 34 adult patients with RP were randomized to two groups. One group, consisted of 16 participants, received lutein supplementation (10 mg/d for 12 wks followed by 30 mg/d) for the first 24 weeks and then placebo for the following 24 weeks, while the other group included 18 participants for whom placebo (24 weeks) was administered prior to lutein. Visual acuity, contrast sensitivity, and central visual field were measured at different illumination levels at baseline and every week using a PC-based test at home. RESULTS: For visual acuity (VA) at normal illumination level, treatment with lutein reduced logMAR, i.e. improved VA, but this effect was not statistically significant. The changes in normal (100%), low (4%), and very low (0.1%) illumination log CS were not statistically significant (p-values: 0.34, 0.23, and 0.32, respectively). Lutein had a statistically significant effect on visual field (p-value: 0.038) and this effect increased in the model assuming a 6-week delay in effect of lutein. Comparing the development of vision measures against the natural loss expected to occur over the course of 48 weeks, most measures showed reduced decline, and these reductions were significant for normal illumination VA and CS. CONCLUSION: These results suggest that lutein supplementation improves visual field and also might improve visual acuity slightly, although these results should be interpreted cautiously. As a combined phase I and II clinical trial, this study demonstrated the efficacy and safety of lutein supplementation

Levels of State and Trait Anxiety in Patients Referred to Ophthalmology by Primary Care Clinicians: A Cross Sectional Study

Purpose There is a high level of over-referral from primary eye care leading to significant numbers of people without ocular pathology (false positives) being referred to secondary eye care. The present study used a psychometric instrument to determine whether there is a psychological burden on patients due to referral to secondary eye care, and used Rasch analysis to convert the data from an ordinal to an interval scale. Design Cross sectional study. Participants and Controls 322 participants and 80 control participants. Methods State (i.e. current) and trait (i.e. propensity to) anxiety were measured in a group of patients referred to a hospital eye department in the UK and in a control group who have had a sight test but were not referred. Response category analysis plus infit and outfit Rasch statistics and person separation indices were used to determine the usefulness of individual items and the response categories. Principal components analysis was used to determine dimensionality. Main Outcome Measure Levels of state and trait anxiety measured using the State-Trait Anxiety Inventory. Results State anxiety scores were significantly higher in the patients referred to secondary eye care than the controls (p0.1). Rasch analysis highlighted that the questionnaire results needed to be split into “anxiety-absent” and “anxiety-present” items for both state and trait anxiety, but both subscales showed the same profile of results between patients and controls. Conclusions State anxiety was shown to be higher in patients referred to secondary eye care than the controls, and at similar levels to people with moderate to high perceived susceptibility to breast cancer. This suggests that referral from primary to secondary eye care can result in a significant psychological burden on some patients

Implementing structured functional assessments in general practice for persons with long-term sick leave: a cluster randomised controlled trial

<p>Abstract</p> <p>Background</p> <p>The increasing attention on functional assessments in medical and vocational rehabilitation requires a focus change for the general practitioners (GP) into paying attention to patient resources, possibilities and coping instead of symptoms, problems and limitations. The GPs report difficulties in performing the requested explicit functional assessments. The purpose of this study was to implement a structured method in general practice for assessing functional ability in persons with long-term sick leave. The study aim was to evaluate intervention effects on important GP parameters; knowledge, attitudes, self-efficacy towards functional assessments and knowledge about patient work factors.</p> <p>Methods</p> <p>Fifty-seven GPs were randomly assigned to an intervention or a control group. The intervention group GPs attended an introductory one-day work-shop and implemented structured functional assessments during an eight months intervention period. GP knowledge, GP attitudes, and GP self-efficacy towards functional assessments, as well as GP knowledge of patient work factors, were collected before, after and six months after the intervention period started. Evaluation score-sheets were filled in by both the intervention GPs and their patients immediately after the consultation to evaluate the GPs' knowledge of patient work factors.</p> <p>Results</p> <p>The intervention GPs reported increased knowledge (B: 0.56, 95% CI (0.19, 0.91)) and self-efficacy (B: 0.90, 95% CI (0.53, 1.26)) towards functional assessments, and increased knowledge about their patients' workplace (B: 0.75, 95% CI (0.35, 1.15)) and perceived stressors (B: 0.55, 95% CI (0.23, 0.88)) with lasting effects at the second follow-up. No intervention effect was seen in relation to GP attitudes. Both before and after the intervention, the GPs were most informed about physical stressors, and less about mental and work organisational stressors (Guttman's reproducibility coefficient: 0.95 and 1.00). After the consultation, both the intervention GPs and their patients reported that the GPs' knowledge about patient work factors had increased (GP B: 0.60 (95% CI: 0.42, 0.78); patient B: 0.50 (95% CI: 0.34, 0.66)).</p> <p>Conclusion</p> <p>Introducing and implementing structured functional assessments in general practice made the GPs capable to assess functional ability of their patients in a structured manner. Intervention effects of increased GP knowledge and GP self-efficacy sustained at the second follow-up.</p

Effects of standard training in the use of closed-circuit televisions in visually impaired adults: design of a training protocol and a randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>Reading problems are frequently reported by visually impaired persons. A closed-circuit television (CCTV) can be helpful to maintain reading ability, however, it is difficult to learn how to use this device. In the Netherlands, an evidence-based rehabilitation program in the use of CCTVs was lacking. Therefore, a standard training protocol needed to be developed and tested in a randomized controlled trial (RCT) to provide an evidence-based training program in the use of this device.</p> <p>Methods/Design</p> <p>To develop a standard training program, information was collected by studying literature, observing training in the use of CCTVs, discussing the content of the training program with professionals and organizing focus and discussion groups. The effectiveness of the program was evaluated in an RCT, to obtain an evidence-based training program. Dutch patients (n = 122) were randomized into a treatment group: normal instructions from the supplier combined with training in the use of CCTVs, or into a control group: instructions from the supplier only. The effect of the training program was evaluated in terms of: change in reading ability (reading speed and reading comprehension), patients' skills to operate the CCTV, perceived (vision-related) quality of life and tasks performed in daily living.</p> <p>Discussion</p> <p>The development of the CCTV training protocol and the design of the RCT in the present study may serve as an example to obtain an evidence-based training program. The training program was adjusted to the needs and learning abilities of individual patients, however, for scientific reasons it might have been preferable to standardize the protocol further, in order to gain more comparable results.</p> <p>Trial registration</p> <p><url>http://www.trialregister.nl</url>, identifier: NTR1031</p

Additional psychometric information and vision-specific questionnaires are available for age-realted macular degeneration

Purpose: To present psychometric information and studies dealing with questionnaires for age-related macular degeneration (AMD) and visually impaired patients in addition to the study by Finger et al. "Quality of life in AMD: a review of available vision-specific psychometric tools". We propose that their literature search should not have focused solely on the specific eye disease AMD. Methods: The literature search was partly replicated (PubMed) by using "visual impairment" instead of "macular degeneration" as free text words. Psychometric information was obtained from the additional studies. Preliminary results from a differential item functioning (DIF) analysis used to examine the relationship between item responses on the Vision-related quality of life Core Measure (VCM1) of AMD patients versus patients with other eye conditions are discussed. Results: Eight studies of visually impaired patient populations, including AMD patients, are discussed, with psychometric information from six vision-specific questionnaires. The VCM1 items did not present DIF, which means that the items were equally interpreted by all patients. Conclusions: The results on DIF and the additional studies presented here confirm that a specific eye disorder is of minor importance in the choice of a vision-specific questionnaire or, in this case, a literature search

Re-evaluating a vision-related quality of life questionnaire with item response theory (IRT) and differential item functioning (DIF) analyses

Background: For the Low Vision Quality Of Life questionnaire (LVQOL) it is unknown whether the psychometric properties are satisfactory when an item response theory (IRT) perspective is considered. This study evaluates some essential psychometric properties of the LVQOL questionnaire in an IRT model, and investigates differential item functioning (DIF). Methods: Cross-sectional data were used from an observational study among visually-impaired patients (n = 296). Calibration was performed for every dimension of the LVQOL in the graded response model. Item goodness-of-fit was assessed with the S-X2-test. DIF was assessed on relevant background variables (i.e. age, gender, visual acuity, eye condition, rehabilitation type and administration type) with likelihood-ratio tests for DIF. The magnitude of DIF was interpreted by assessing the largest difference in expected scores between subgroups. Measurement precision was assessed by presenting test information curves; reliability with the index of subject separation. Results: All items of the LVQOL dimensions fitted the model. There was significant DIF on several items. For two items the maximum difference between expected scores exceeded one point, and DIF was found on multiple relevant background variables. Item 1 ‘Vision in general’ from the “Adjustment” dimension and item 24 ‘Using tools’ from the “Reading and fine work” dimension were removed. Test information was highest for the “Reading and fine work” dimension. Indices for subject separation ranged from 0.83 to 0.94. Conclusions: The items of the LVQOL showed satisfactory item fit to the graded response model; however, two items were removed because of DIF. The adapted LVQOL with 21 items is DIF-free and therefore seems highly appropriate for use in heterogeneous populations of visually impaired patients. (aut.ref.

The relationship between stimulus intensity and response amplitude for the photopic negative response of the flash electroretinogram

The aim of this study was to investigate the relationship between stimulus intensity and response amplitude for the photopic negative response (PhNR) of the flash ERG. Specific aims were (i) to determine whether a generalized Naka-Rushton function provided a good fit to the intensity-response data and (ii) to determine the variability of the parameters of the best-fitting Naka-Rushton models. Electroretinograms were recorded in 18 participants, on two occasions, using both DTL fibre and skin active electrodes, in response to Ganzfeld red stimuli (Lee filter "terry red") ranging in stimulus strength from -1.30 to 0.53 log cd.s.m(-2) (0.28-2.11 log phot td.s) presented over a steady blue background (Schott glass filter BG28; 3.9 log scot td). PhNR amplitude was measured from b-wave peak and from pre-stimulus baseline. The Naka-Rushton function was fitted to all intensity-response data, and parameters, 'n', 'Vmax' and 'K' were obtained. Coefficients of variation (CoV), and inter-ocular and inter-session limits of agreement (LoA) were calculated for both Naka-Rushton parameters. A generalized Naka-Rushton function was found to provide a good fit to the intensity-response data, except at the highest stimulus intensity, where a reduction in amplitude occurred in many individuals. The 'Vmax' parameter was less variable than 'K' for all intensity-response data. Variability was lower for DTL than skin electrodes, and for peak-to-trough PhNR measurements, compared to baseline-to-trough. This study has demonstrated for the first time that the Naka-Rushton model provides a useful means of quantifying the intensity-response relationship of the PhNR