A Comprehensive Evaluation of the Precision (Repeatability and Reproducibility) of the Oculus Pentacam HR

This article is made available with the permission of the publisher, Association for Research in Vision and OphthalmologyPurpose.: To evaluate the precision (repeatability and reproducibility) of the Pentacam HR (high-resolution) tomographer (Oculus, Wetzlar, Germany) across a large range of measurement parameters. Methods.: A randomly selected healthy eye of 100 subjects was scanned twice with the Pentacam HR by one observer for each of the three measurement modes: 25-picture (1 second) scan, 50-picture (2 second) scan, and cornea fine scan (50 pictures in 1 second). The repeatability of each scan mode was assessed. One additional 25-picture scan was acquired by a second observer to test reproducibility. Results.: Overall, the Pentacam HR had good precision, with the cornea fine scan returning the most precise results. The 25- and 50-picture scans showed similar precision. The repeatability limits, expressed as the within-subject SD × 1.96√2 of the anterior keratometry (K)1 and K2 readings with the standard 25-picture scan, were 0.25 and 0.36 D, respectively. Pachymetry maps, corneal maps, anterior chamber depth maps, corneal volume, topometric Q values and indices were also found to be precise. Poor precision was found for estimates of axis (astigmatic and progression index), pupil center pachymetry, single points on corneal maps, refractive power maps, and equivalent K readings. Conclusions.: Measurements taken with the Pentacam HR are repeatable and reproducible, especially those obtained with the cornea fine scan. Although the Pentacam HR is clearly a very useful clinical and research tool, the measurement of corneal axes, pupil center pachymetry, front meridional and axial maps, refractive power maps, and equivalent K readings should be interpreted with caution

The Right PREMTM: Rasch analysis of a new patient reported experience measure for use by older people in hospital

Healthcare rights exist to protect older people from harm and to empower older people to participate in their care with independence, choice and control. Multiple investigations revealing abuse provide evidence that older people’s rights are being breached. Older people must have the opportunity to report on their experience of care against their rights. The Right PREMTM is a new instrument designed to measure older people’s experience of care against their healthcare rights. The objective of this cross-sectional validation study was to assess the psychometric properties of a new instrument to measure the experience of care consistent with the healthcare rights of older people in the hospital setting. Data were collected from older people who were current hospital inpatients of medical wards in four South Australian metropolitan hospitals. The Rasch model was used to assess the psychometric properties of the patient version of The Right PREMTM. The analysis was performed using the Winsteps® software program. Two hundred older patients completed the 50-item questionnaire. During the process of analysis, four items were removed as they did not fit the model and a further 11 items were removed due to high residual correlations. The final 23 items had a Person Separation Index of 2.23, a Person Separation Reliability Coefficient 0.83, an Item Separation Index of 7.70 and an Item Separation Reliability Coefficient of 0.98. Rasch analysis of the patient version of The Right PREMTM, based on a robust sample, demonstrated this new instrument is psychometrically sound and warrants ongoing development. Experience Framework This article is associated with the Policy & Measurement lens of The Beryl Institute Experience Framework. (https://www.theberylinstitute.org/ExperienceFramework). Access other PXJ articles related to this lens. Access other resources related to this lens

Effectiveness of the community-based Low Vision Service Wales: a long-term outcome study

Aims To evaluate the long-term effectiveness of the community-based Low Vision Service Wales (LVSW). Methods A long-term observational study of the Government-funded, community-based, low-vision rehabilitation service which operates in over 180 optometry practices in Wales. Participants were recruited from the LVSW (n=342; 246 women; median age 82 years) at baseline (before the Low Vision intervention). The primary outcome measure was change in visual disability as evaluated by the seven-item National Eye Institute Visual Function Questionnaire (NEI-VFQ). Change was measured on the same cohort at three separate time points, and comparisons were made between these: baseline–3 months; 3–18 months; baseline–18 months. Secondary outcome measures included: use of low-vision aids (LVAs) and satisfaction with the service provided. Results Questionnaires were sent to 281 participants (whose visual disability had been measured at baseline and 3 months) at 18 months postintervention. Responses were received from 190 (67.6%) people; 24 were deceased. Self-reported visual disability was significantly reduced (Wilcoxon Signed Rank (WSR) test: p<0.001) between baseline and 18 months by −0.28 logits (−1.24 to 0.52). This was less than that found between baseline and 3 months; −0.61 logits (−1.81 to 0.02). At 18 months, 79% patients used their LVAs at least once a week which was not significantly different to that found at 3 months (WSR: p=0.127). Conclusions This study provides evidence that the effect of the LVSW persists over a period of 18 months; disability is reduced from baseline, and use of LVAs remains high

Subjective Quality of Vision Before and After Cataract Surgery

This article is made available in accordance with the publisher's public repositories policy.Objective To investigate the effect of cataract surgery on subjective quality of vision. Methods The Quality of Vision (QoV) questionnaire (Italian translation) was completed before and 3 months after cataract surgery in 4 groups of patients recruited from September through December 2010: first eye with ocular comorbidity, first eye without ocular comorbidity, second eye with ocular comorbidity, and second eye without ocular comorbidity. The questionnaire measures 3 aspects of quality of vision: frequency, severity, and bothersome nature of symptoms. The Lens Opacities Classification System (LOCS) III was used for cataract grading. Friedman and Kruskal-Wallis H tests were performed to compare QoV scores within and between groups. Spearman rank correlations (rs) were calculated to investigate the correlation between LOCS III and QoV symptoms. Results Two hundred twelve patients (mean [SD] age, 74.2 [8.7] years) were recruited, and 212 eyes were included in the study. Improvements in QoV scores were found in all 4 groups (P .05) differences among the 4 groups in the improvement in QoV scores or in the preoperative or postoperative scores. Blurred vision was correlated with posterior subcapsular cataract (rs = 0.420, P = .04). Conclusions Cataract in one or both eyes causes a similar loss in subjective quality of vision, which is also irrespective of the presence of ocular comorbidity. Posterior subcapsular cataract causes the specific symptom “blurred vision.” Cataract surgery resulted in a large and comparable improvement in subjective quality of vision, regardless of ocular comorbidity and first or second eye surgery

Reengineering the Glaucoma Quality of Life-15 Questionnaire with Rasch Analysis

This article is made available with the permission of the publisher, Association for Research in Vision and OphthalmologyPurpose.: To investigate, using Rasch analysis, whether the 15-item Glaucoma Quality of Life-15 (GQL-15) forms a valid scale and to optimize its psychometric properties. Methods.: One hundred eighteen glaucoma patients (mean age, 65.7 years) completed the German-version of the GQL-15. Rasch analysis was performed to assess category function (how respondents differentiated between the response options), measurement precision (discriminative ability), unidimensionality (whether items measure a single construct), targeting (whether items are of appropriate difficulty for the sample), and differential item functioning (whether comparable subgroups respond differently to an individual item). Where any of these attributes were outside acceptable ranges, steps were taken to improve the instrument. Results.: The five-response categories of the GQL-15 were well differentiated by respondents, as demonstrated by ordered and well-spaced category thresholds. The GQL-15 had an excellent measurement precision but demonstrated poor targeting of item difficulty to person ability and multidimensionality, indicating that it was measuring more than one construct. Removal of six misfitting items created a nine-item unidimensional instrument with good measurement precision and no differential item functioning but poor targeting. A new name, the Glaucoma Activity Limitation (GAL-9) questionnaire, is proposed for the short version, which better reflects the construct under measurement. Conclusions.: The GAL-9 has superior psychometric properties over the GQL-15. Its only limitation is poor targeting of item difficulty to person ability, which is an inevitable attribute of a vision-related activity limitation instrument for glaucoma patients, most of whom have only peripheral visual field defects and little difficulty with daily activities

The Importance of Rating Scale Design in the Measurement of Patient-Reported Outcomes Using Questionnaires or Item Banks

This article is made available with the permission of the publisher, Association for Research in Vision and OphthalmologyPurpose.: To investigate the effect of rating scale designs (question formats and response categories) on item difficulty calibrations and assess the impact that rating scale differences have on overall vision-related activity limitation (VRAL) scores. Methods.: Sixteen existing patient-reported outcome instruments (PROs) suitable for cataract assessment, with different rating scales, were self-administered by patients on a cataract surgery waiting list. A total of 226 VRAL items from these PROs in their native rating scales were included in an item bank and calibrated using Rasch analysis. Fifteen item/content areas (e.g., reading newspapers) appearing in at least three different PROs were identified. Within each content area, item calibrations were compared and their range calculated. Similarly, five PROs having at least three items in common with the Visual Function (VF-14) were compared in terms of average item measures. Results.: A total of 614 patients (mean age ± SD, 74.1 ± 9.4 years) participated. Items with the same content varied in their calibration by as much as two logits; “reading the small print” had the largest range (1.99 logits) followed by “watching TV” (1.60). Compared with the VF-14 (0.00 logits), the rating scale of the Visual Disability Assessment (1.13 logits) produced the most difficult items and the Cataract Symptom Scale (0.24 logits) produced the least difficult items. The VRAL item bank was suboptimally targeted to the ability level of the participants (2.00 logits). Conclusions.: Rating scale designs have a significant effect on item calibrations. Therefore, constructing item banks from existing items in their native formats carries risks to face validity and transmission of problems inherent in existing instruments, such as poor targeting

Establishing Levels of Indications for Cataract Surgery: Combining Clinical and Questionnaire Data into a Measure of Cataract Impact

This article is made available with the permission of the publisher, Association for Research in Vision and OphthalmologyPurpose.: To develop a model for establishing indications for cataract surgery that incorporates clinical and questionnaire data on a single linear scale using Rasch analysis. Methods.: In this prospective study, 293 preoperative cataract surgery patients (mean age, 72.8 ± 10 years; age range, 33–98 years; 174 female, 119 male; 49% with ocular comorbidity) completed two questionnaires, and visual acuity was measured in each eye. A cataract impact model was developed using Rasch analysis incorporating questionnaire scores and visual acuity. Participants were ranked from 1 to 293 based on the order in which they presented (first in first out [FIFO]) and then were ranked based on the cataract impact model. The main outcome measure was the number of participants moving 49 (16.7% change) rank positions, which represented a likelihood to change priority category. Results.: The cataract impact model was unidimensional (fit statistics within 0.66–1.68) and had adequate precision (person separation of 2.58), and the components were well targeted to the population (0.05 logits between the mean item difficulty and person ability). Two hundred twenty-seven (77.5%) patients moved by at least 49 rank positions. Conclusions.: It is possible to combine clinical and questionnaire data and rank patients on a single linear scale. This approach modifies the ranking that occurs with the FIFO model and can be used for prioritizing patients for surgical intervention. More sophisticated models incorporating more clinical information may provide a better measure of the cataract impact latent trait

Identifying Content for the Glaucoma-specific Item Bank to Measure Quality-of-life Parameters

"This is a non-final version of an article published in final form in Khadka J, McAlinden C, Craig JE, Fenwick EK, Lamoureux EL, Pesudovs K. Identifying content for the glaucoma-specific item bank to measure quality-of-life parameters. Journal of Glaucoma . 2015 Jan;24(1):12-9. doi: 10.1097/IJG.0b013e318287ac11.". Author manuscript version made available in accordance with publisher copyright policy.PURPOSE: Patient-reported outcomes (PROs) have become essential clinical trial end points. However, a comprehensive, multidimensional, patient-relevant, and precise glaucoma-specific PRO instrument is not available. Therefore, the purpose of this study was to identify content for a new, glaucoma-specific, quality-of-life (QOL) item bank. METHODS: Content identification was undertaken in 5 phases: (1) identification of extant items in glaucoma-specific instruments and the qualitative literature; (2) focus groups and interviews with glaucoma patients; (3) item classification and selection; (4) expert review and revision of items; and (5) cognitive interviews with patients. RESULTS: A total of 737 unique items (extant items from PRO instruments, 247; qualitative articles, 14 items; focus groups and semistructured interviews, 476 items) were identified. These items were classified into 10 QOL domains. Four criteria (item redundancy, item inconsistent with domain definition, item content too narrow to have wider applicability, and item clarity) were used to remove and refine the items. After the cognitive interviews, the final minimally representative item set had a total of 342 unique items belonging to 10 domains: activity limitation (88), mobility (20), visual symptoms (19), ocular surface symptoms (22), general symptoms (15), convenience (39), health concerns (45), emotional well-being (49), social issues (23), and economic issues (22). CONCLUSIONS: The systematic content identification process identified 10 QOL domains, which were important to patients with glaucoma. The majority of the items were identified from the patient-specific focus groups and semistructured interviews suggesting that the existing PRO instruments do not adequately address QOL issues relevant to individuals with glaucoma

A retrospective evaluation of the Brain and Body Fitness Studio service on functional capacity and quality of life in people with neurological disorders

BackgroundPeople with neurological disorders (ND) are less physically active than the general population due to physical, sensory, and/or cognitive impairments. These individuals often feel intimidated to join mainstream health and wellness centers due to lack of specialized support for people with ND. The Brain and Body Fitness Studio (BBFS) is one of the first Accredited Exercise Physiologist-led interprofessional services in Adelaide South Australia to provide individualized evidence-based multimodal exercise prescription and social support for this population. This comprehensive retrospective study evaluated the impact of BBFS on functional capacity (FC) determined as the 6-min walk distance (6 MWD) achieved during a 6-min walk test (6 MWT), of its members with ND.MethodsSixty-two BBFS members (age, 66 ± 10 years; 60% male) with ND (85% Parkinson's Disease; average time since diagnosis, 4 years [IQR, 2 to 12 years]) and complete pre- and post-6-month clinical assessment of the primary outcome of the study, the 6 MWD, were included in this retrospective analysis. A series of sub-analyses were also performed to investigate the effects of adherence to the recommended prescription of at least twice a week in the program (≥80 vs. &lt; 80% adherence), and disease stage (time since diagnosis; ≥6 vs. &lt; 6 years) on FC.ResultsAlthough there was no statistically significant change in 6 MWD from pre- to post-6-month BBFS program (+15 ± 90 m, p = 0.19), a clinically meaningful improvement of &gt;14 m was evident. Improvement in 6 MWD was significantly greater in members who attended at least 80% of the recommended visits (≥80% visits, +37 ± 58 m; ≤ 80% visits,−1 ± 105 m, p = 0.046). We also found a 6 MWD improvement from pre- to post-6 months in those in the early years of their ND (&lt; 6 years since diagnosis, +39 ± 76 m), but not in those in the later years of their ND (≥6 years since diagnosis, −36 ± 123 m, between group difference, p = 0.029).ConclusionA clinically meaningful 6 MWD improvement may be elicited by services provided by BBFS in people with ND. Overall, the benefits appear to be more evident in members who attended the BBFS for at least 80% of the recommended visits and those who were in the early stage of their ND diagnosis

Validation and use of quality of life impact of refractive correction questionnaire in spectacle wearers in Malawi:A clinic-based study

BACKGROUND: To assess the psychometric properties of the QIRC questionnaire and use it as an outcome measure in spectacle wearers attending an eye clinic in Malawi. METHODS: Participants who had uncorrected distance visual acuity of below 6/18 and improved to 6/9 or better with spectacles on both eyes were included in the study. The participants self-administered the Chichewa version of the QIRC questionnaire that was translated and culturally adapted for Malawian settings. Psychometric evaluation of the QIRC responses was carried out using the WinSteps software (Version 3.92.1; Winsteps, Chicago, IL) by applying the Andrich rating scale model of the Rasch analysis. RESULTS: One hundred and forty-three participants (mean age ± standard deviation, 27.64 ± 2.91; age range; 16 to 39 years; male, 51.7%) completed the QIRC. The Chichewa QIRC had satisfactory psychometric properties (Ordered response categories, Person separation index, 1.93; Item separation index, 3.42; Targeting 0.70) including excellent Rasch-model fit statistics (Infit and Outfit MnSq 0.05 for all). The QIRC scores negatively correlated with uncorrected visual acuity (in logMAR) in the better eye (spearman's rho=−0.34, p < 0.001). CONCLUSION: The translated and culturally adapted version of the QIRC Questionnaire had satisfactory psychometric properties to measure the refractive error-specific quality of life in Malawi. It performed well as an outcome measure of spectacle wear