Impact of Glaucoma on Visual Functioning in Indians

Evaluating Measurement Properties of Patient-Reported Outcome Measures in Glaucoma: A Systematic Review

TOPIC

The purpose of the current study was to systematically identify and evaluate existing patient-reported outcome measures (PROMs) for clinical glaucoma practice.

CLINICAL RELEVANCE

Understanding and incorporating patient preferences into decision-making is now recognized as critical for optimal resource allocation, especially in technologically advancing areas, such as minimally invasive surgeries. Patient-reported outcome measures are instruments designed to evaluate the health outcomes that are most important to patients. Despite their recognized importance, especially in the era of patient-centered care, their routine use in clinical settings remains low.

METHODS

A systematic literature search was conducted in 6 databases (EMBASE, MEDLINE, PsycINFO, Scopus, BIOSIS, and Web of Science) from the date of inception. Studies were included in the qualitative review if they reported measurement properties of PROMs in adult patients with glaucoma. COnsensus-based Standards for the selection of health Measurement INstruments guidelines were used to assess the included PROMs. The study protocol is registered with PROSPERO (registration number: CRD42020176064).

RESULTS

The literature search yielded 2661 records. After deduplication, 1259 studies entered level 1 screening, and based on title and abstract review, 164 records proceeded to full-text screening. In 48 included studies, 70 instrument reports discuss 43 distinct instruments in 3 major categories: glaucoma-specific, vision-specific, and general health-related quality of life. Most used measures were glaucoma-specific (Glaucoma Quality of Life [GQL] and Glaucoma Symptom Scale [GSS]) and vision-specific (National Eye Institute Visual Function Questionnaire [NEI VFQ-25]). All 3 have sufficient validity (especially construct), with GQL and GSS having sufficient internal consistency, cross-cultural validity, and reliability, with reports suggesting high methodological quality.

CONCLUSION

The GQL, GSS, and NEI VFQ-25 are the 3 most used questionnaires in a research setting, having considerable validation in a patient population with glaucoma. Limited reports on interpretability, responsiveness, and feasibility in all 43 identified instruments make identifying a single optimal questionnaire for clinical use challenging and highlight the need for further studies.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Development and validation of the 40-item Glaucoma Visual Functioning Questionnaire

AIMS

To evaluate the psychometric properties of a newly designed questionnaire, the 40-item Glaucoma Visual Functioning Questionnaire (GVFQ-40), in a Chinese sample to capture the visual ability of patients with glaucomatous vision impairment in five domains.

METHODS

Eighty-four glaucoma suspects (controls) and 270 glaucoma patients were recruited from the Glaucoma Clinic at Zhongshan Ophthalmic Centre in this cross-sectional, observational study. All subjects completed two questionnaires during routine clinical visits: the GVFQ-40 and the validated National Eye Institute Visual Functioning Questionnaire-25 (NEI VFQ-25). The discriminant, criterion-related and construct validity of the GVFQ-40 were assessed. A subset of subjects completed the GVFQ-40 twice, with an interval of 7-21 days, to determine test-retest reliability.

RESULTS

Domain-specific and total GVFQ-40 scores were significantly higher (worse visual ability) in glaucoma patients than in controls (all p<0.001). All pairwise subgroup comparisons were statistically significant except for the 'mobility' domain comparison between the mild visual field loss and control groups (p=0.189). Significant differences between these two groups were observed in only 2 of the 12 dimensions on the NEI VFQ-25. The GVFQ-40 results demonstrated strong correlations with better-eye mean deviation and Visual Field Index (glaucoma severity measures). Exploratory factor analysis tended to confirm a three-domain structure. Test-retest intraclass correlation coefficients were higher than 0.927 for domain-specific and total GVFQ-40 scores.

CONCLUSIONS

The GVFQ-40 possesses good validity and reliability. It can be used to evaluate the impact of glaucomatous damage on visual ability and has potential in the evaluation of intervention efficacy.

TRIAL REGISTRATION NUMBER

NCT04722861.

Socio-Demographic, lifestyle and eye-related factors associated with quality of life Among people with glaucoma in Serbia

PURPOSE

The purpose of this study was to examine socio-demographic, lifestyle and ophthalmological factors associated with poorer Vision Related Quality of Life (VRQoL) in people with glaucoma.

METHODS

This cross-sectional study included 306 consecutive patients with glaucoma who presented for regular check-ups at the referral center in Belgrade (Serbia) from August 2015 to September 2016. The diagnosis of glaucoma was based on the glaucomatous disc cupping and reproducible visual field impairment on one or both eyes. Quality of life was examined using the validated Glaucoma Quality of Life-15 (GQL-15) and the National Eye Institute Visual Function Questionnaire 25 (NEI VFQ 25).

RESULTS

A series of adjusted linear regression models showed that glaucoma patients with higher educational attainment, who were employed and still driving had better VRQoL. Worse visual acuity and visual field defect, being in later glaucoma stages, having lower intraocular pressure, having two laser interventions as well as having pseudo-exfoliative glaucoma was associated with worse VRQoL. Intake of fewer medications and having had no trabeculectomies on better eye as well as taking less drops per day on worse eye were associated with better VRQoL.

CONCLUSIONS

Several socio-demographic, lifestyle and ocular factors can impact VRQoL in glaucoma patients. Identifying people who are at risk of having worse VRQoL could allow for earlier interventions, such as changes in therapy, undergoing surgery, use of mobility aids etc.

Visual field progression in Malay patients with primary glaucoma: survival analysis and prognostic factors

PURPOSE

This study aims to determine the 5-year visual field progression and identify the prognostic factors for progression in Malay patients with primary glaucoma.

METHODS

A retrospective cohort record review study was conducted among 222 patients (222 eyes) with primary glaucoma who were selected from a glaucoma research database of a tertiary center in Malaysia. The patients were Malays and diagnosed with primary open-angle glaucoma (POAG) or primary angle-closure glaucoma (PACG). Patients who were followed up regularly for at least 6 months between 1 January 2009 and 31 December 2014 and completed another 1-year follow-up after recruitment (between 1 January 2015 and 31 December 2015) were selected. Multiple prognostic factors that influence visual field progression were identified. Progression of visual field loss was based on the Advanced Glaucoma Intervention Study and Hodapp-Parrish-Anderson scores. Kaplan-Meier survival and Cox proportional hazard regression analyses were performed.

RESULTS

Sixty-three patients (28.4%) developed visual field progression after a mean (SD) follow-up of 6.9 (3.3) years. Those with POAG progressed faster (mean time, 10.6 years; 95% confidence interval [CI], 9.3, 11.9) than those with PACG (17.3 years; 95% CI, 14.8, 19.9) but not statistically significant. Disc hemorrhage and history of eye pain increased the risk of progression by 2.8-folds (95% CI, 1.6, 4.8) and 2.5-folds (1.4, 4.4), respectively.

CONCLUSION

The 5-year survival of the Malay primary glaucoma patients with visual field progression was similar with that of other Asian populations. However, aggressive management is required for those with disc hemorrhages and eye pain related to increased intraocular pressure.

Patient-reported Outcomes, Functional Assessment, and Utility Values in Glaucoma

In clinical glaucoma research, the measurement of patient reported outcomes, functional assessment of disability, and health economic impact is critical. However, valid, time-efficient and comprehensive tools are not available and several current instruments lack in the appropriate precision for measuring the various dimensions of glaucoma-related quality of life (QoL), including functioning and mobility. Furthermore, statistical methods are inconsistently and sometimes incorrectly used in otherwise sound clinical studies. Standardizing and improving methods of patient-centered data collection and analysis in glaucoma studies are imperative. This paper outlines recommendations and provides a discussion of some of the pertinent issues relating to the optimization of patient-reported outcomes research in glaucoma.

Vision Parameters Most Important to Functionality in Glaucoma

Purpose

To determine the importance of various vision parameters to functionality in glaucoma.

Methods

Vision was measured using seven parameters: visual acuity (VA), contrast sensitivity (CS), integrated visual field (IVF), area under the log CS function (AULCSF), color vision, stereoacuity, and VA with noise (ViN). Likelihood ratio testing (LRT) determined if the full set of visual parameters significantly explained variability in 10 functional outcomes. For outcomes where the visual contribution was significant, dominance analysis determined the relative importance of the various visual parameters.

Results

The analysis included 151 glaucoma patients. Mean age was 70 ± 6.8 years, and 47% were men. Significant visual contributions (LRT P < 0.05) were noted for glaucoma quality of life (GQL-15), reading speed, driving cessation, daily steps, and base of support while walking, but not for fear of falling, balance, gait velocity, stride velocity, and stride length while walking (LRT P > 0.05). The most important parameter (and percent contribution) to vision-explained variability were AULCSF for daily steps (45%), IVF for base of support (35%), VA for reading speed (34%), CS for GQL-15 (30%), and VA for driving cessation (26%).

Conclusions

Measures of visual ability are important for several aspects of quality of life and functionality. The most important vision parameter for functionality differs depending on the domain studied. Reading and driving were explained by VA and IVF sensitivity. On the other hand, GQL-15 and daily steps were more heavily influenced by CS and AULCSF, which are rarely performed clinically.

Evaluation of Vision-related Quality of Life in Patients with Glaucoma: A Hospital-based Study

Introduction

Quality of life (QoL) is a broad concept that is affected in a complex way by many factors. Healthcare interventions are targeted now days to improve quality of life of affected individuals. Glaucoma is a major cause of irreversible blindness throughout the world and affects patient's quality of life in several ways. In present study, we aim to evaluate and quantify vision related quality of life in glaucoma patients in a tertiary care hospital setting.

Materials and methods

Vision related quality of life was evaluated in glaucoma patients using GQL-15 questionnaire, which compares the subjective performance of various vision related tasks in these patients. Fifty diagnosed cases of glaucoma and fifty healthy volunteers were included in the study. In both these groups, standard tests for visual function were done and both were assigned to complete the questionnaire. GQL-15 questionnaire includes 15 items divided between 4 factors pertaining to visual disability: central and near vision, peripheral vision, dark adaptation and glare, and outdoor mobility. Higher scores indicate greater difficulty in performing vision-related activities and poorer QoL.

Results

A total of 100 cases were enrolled out of which 50 were diagnosed glaucoma cases and 50 were controls. Almost three fourth of glaucoma patients, i.e., 72% were diagnosed as chronic open angle glaucoma where 24% were angle closure patients and rest 4% were normal tension glaucoma patients. The mean GQL score of glaucoma cases was 26.00 ± 10.84 and for controls it was 15.02 ± 0.14 (p value < 0.05). All subscale scores also showed a uniform rise in their value as we move from mild to severe cases thereby concluding that all visual parameters worsen with increase in severity pattern of disease.

Conclusions

As glaucoma patients have reduced vision related quality of life, so every effort should be made to preserve visual functions in these patients. Many activities that define independence and productivity in society require good vision and hence one of most devastating consequences of advancing visual impairment in glaucoma is progressive loss of independence thereby affecting patients quality of life.

How to cite this article

Dhawan M, Hans T, et al. Evaluation of Vision-related Quality of Life in Patients with Glaucoma: A Hospital-based Study. J Curr Glaucoma Pract 2019;13(1):9–15.

Glaucoma-Associated Visual Task Performance and Vision-Related Quality of Life in South India

OBJECTIVE/PURPOSE

Performance-based measures may provide an objective assessment of how glaucoma affects daily functioning. We sought to validate a clinically-applicable performance-based measure of visual ability for patients with glaucoma in south India and to describe its relationship to clinical and patient-reported outcomes.

DESIGN

Cross-sectional validation study.

SUBJECTS/PARTICIPANTS/CONTROLS

145 participants with glaucoma were recruited at Aravind Eye Hospital.

METHODS/INTERVENTION/TESTING

We modified the compressed assessment of activities related to vision (CAARV), a performance-based measure validated in the U.S., to be culturally relevant in south India. Participants underwent a series of tests, including the Indian CAARV (I-CAARV), Indian Visual Functioning Questionnaire (IND-VFQ), Spaeth/Richman Contrast Sensitivity (SPARCS) test, standard automated perimetry, and visual acuity (VA). Factor analysis and Rasch modeling were used to validate the I-CAARV. Correlations between the I-CAARV and other outcomes were evaluated.

MAIN OUTCOME MEASURE

Psychometric properties of the I-CAARV for individuals with glaucoma in south India.

RESULTS

The study included 142 participants (51.7% female, mean age 56.4 years). Average presenting visual acuity and visual field mean deviation (MD) in the better-seeing eye were 0.26 logMAR and -6.57 dB, respectively. The four tasks of the I-CAARV were found to measure a single underlying construct. Rasch analysis of the I-CAARV revealed that the outcome measure had moderate reliability, good construct and content validity, and fair measurement precision. Tasks were well-targeted to the study sample. Rasch-calibrated scores on the I-CAARV were significantly correlated with Rasch-calibrated IND-VFQ scores (r=-0.54) and with visual field MD, presenting VA, best-corrected VA, and SPARCS contrast sensitivity in both the better-seeing eye (r=0.60, -0.51, -0.53, 0.76, respectively) and worse-seeing eye (r=0.48, -0.61, -0.46, 0.69, respectively).

CONCLUSIONS

The I-CAARV is a valid performance-based measure of vision-dependent functioning in glaucoma in south India. This study also found that I-CAARV task performance was strongly correlated with contrast sensitivity and suggests that performance-based and patient-reported outcomes are related but distinct measures of the impact of glaucoma on functioning and vision-related quality of life. Future studies are needed to determine the sensitivity of the I-CAARV to detect changes due to disease progression that are relevant to functioning and vision-related quality of life.

Comparison of Visual Field Progression Rates Among the High Tension Glaucoma, Primary Angle Closure Glaucoma, and Normal Tension Glaucoma

Purpose

To compare the visual field (VF) progression among high tension glaucoma (HTG), primary angle closure glaucoma (PACG), and normal tension glaucoma (NTG) subjects in routine clinical care.

Methods

All patients had ≥5 VF tests using HFA, 24-2, SITA-standard strategy. We compared the progression between glaucoma subtypes after matching the VFs for baseline severity (mean deviation [MD]) and the age at presentation. Global VF progression was evaluated by linear regression analysis (LRA) of MD. For local VF progression, scotoma expansion (SE) defined as appearance of new scotoma and scotoma deepening (SD) defined by pointwise LRA were calculated. SE and SD were analyzed in three VF zones: superior arcuate (SA), inferior arcuate (IA), and central (C).

Results

A total of 310 HTG, 304 PACG, and 165 NTG eyes were included. When VFs were matched by baseline MD, a greater number (n = 20/76) of eyes with HTG showed significant progression compared to PACG (n = 9/76; P = 0.04). The number of progressing eyes were not significantly different between HTG and NTG (n = 11/76; P = 0.10) and between NTG and PACG (P = 0.65). When the baseline VFs were matched by age, the number of eyes showing significant progression were similar in all the subtypes. SA zone in HTG and NTG showed greater SE and SD compared to other zones (P < 0.05), whereas IA zone in PACG showed greater SE and SD compared to other zones (P < 0.05).

Conclusions

In our cohort of treated primary glaucoma with matched baseline severity, a greater proportion of HTG eyes progressed faster compared to PACG. SA zone in HTG and NTG and IA zone in PACG showed greater VF progression.

Glaucoma Symptom Scale: Psychometric properties of the Serbian version

Purpose

The study aim was to translate and validate the Glaucoma Symptom Scale (GSS) in Serbian language.

Methods

Clinical parameters and socio-demographic data were collected for each of the 177 enrolled glaucoma patients. Each eye was classified according to the Glaucoma staging system by Mills into 6 stages. Patients filled out the GSS and National Eye Institute Visual Function Questionnaire (NEI-VFQ 25). The GSS comprises 10 complaints common for glaucoma patients on a topical treatment, grouped into two subscales: SYMP-6 (non-visual) and FUNC-4 (visual problems). The GSS was translated following the customary methodology and its psychometric properties were assessed by using both Classical Test Theory (CTT) and Rasch analysis.

Results

The internal consistency of the Serbian GSS for the whole scale was very good (Cronbach’s alpha = 0.81). On factor analysis items were clustered into 2 factors (48.92% of variance) which corresponded to the original scale. The total and subscale GSS scores correlated significantly with measures of disease severity and also with total score and analogous NEI-VFQ 25 subscale scores. In Rasch analysis we obtained adequate item reliability index (0.90). Almost all items had infit and outfit mean squares in the accepted range. However, measurement precision was poor (low person separation reliability) and targeting revealed a ceiling effect.

Conclusion

When analyzed with CTT the Serbian version of the GSS seems to be a valid instrument, but Rasch analysis revealed some serious measurement flaws, therefore it should not be used in its current format. Further studies to modify and improve GSS are needed prior to its application for Serbian glaucoma patients.

Validation of the Glaucoma Quality of Life-15 Questionnaire in Serbian language

AIM

To translate the Glaucoma Quality of Life-15 (GQL-15) to Serbian language and asses its validity and reliability in the population of Serbian patients.

METHODS

The study included 177 glaucoma patients. Clinical parameters (visual acuity, mean defect and square root of loss variance of visual field) and socio-demographic data were collected. Patients were stratified according to the Nelson's glaucoma staging system as mild, moderate and advanced glaucoma. All patients filled out the GQL-15 and National Eye Institute Visual Function Questionnaire (NEI-VFQ 25). The GQL-15 was translated following the internationally-accepted methodology, and its psychometric properties were assessed by using classical test theory and Rasch analysis.

RESULTS

The mean total score for the GQL-15 was 20.68±7.31. The Cronbach's alpha coefficient for the whole scale was 0.89 (central and near vision, α=0.24; peripheral vision, α=0.85; glare and dark adaptation, α=0.83). Factor analysis established 4 factors (70.3% of variance): two corresponding to the original factors and two new factors specific for the Serbian population. The GQL-15 score correlated positively with almost all clinical parameters and NEI-VFQ 25 proving good criterion validity. Correlation of the GQL-15 total score on test-retest confirmed appropriate scale reproducibility (ρ=0.96, P<0.001). The GQL-15 discriminated well advanced from mild and moderate glaucoma. In Rasch analysis we obtained adequate item (0.95) reliability index. Almost all items had infit and outfit mean squares in the accepted range.

CONCLUSION

Serbian version of the GQL-15 demonstrates adequate reliability and validity. This version of the GQL-15 is a valid instrument for evaluation of quality of life among Serbian speaking patients with glaucoma and can be applied in daily clinical work.

Strategies to design antimicrobial contact lenses and contact lens cases

Contact lens wear is a primary risk factor for developing ocular complications, such as contact lens acute red eye (CLARE), contact lens-induced peripheral ulcer (CLPU) and microbial keratitis (MK). Infections occur due to microbial contamination of contact lenses, lens cases and lens care solution, which are exacerbated by extended lens wear and unsanitary lens care practices. The development of microbial biofilms inside lens cases is an additional complication, as the developed biofilms are resistant to conventional lens cleaning solutions. Ocular infections, particularly in the case of MK, can lead to visual impairment or even blindness, so there is a pressing need for the development of antimicrobial contact lenses and cases. Additionally, with the increasing use of bandage contact lenses and contact lenses as drug depots and with the development of smart contact lenses, contact lens hygiene becomes a therapeutically important issue. In this review, we attempt to compile and summarize various chemical strategies for developing antimicrobial contact lenses and lens cases by using silver, free-radical producing agents, antimicrobial peptides or by employing passive surface modification approaches. We also evaluated the advantages and disadvantages of each system and tried to provide input to future directions. Finally, we summarize the developing technologies of therapeutic contact lenses to shed light on the future of contact lens applications.

Measuring Health-Related Quality of Life in Strabismus: A Modification of the Adult Strabismus-20 (AS-20) Questionnaire Using Rasch Analysis

Purpose

To evaluate the psychometric properties of the Adult Strabismus-20 (AS-20)- a health-related quality of life (HRQoL) questionnaire in adults with strabismus, and if flawed, to revise the AS-20 and its subscales creating valid measurement scales.

Methods

584 adults (meanage, 27.5 years) with strabismus were recruited from an outpatient clinic at a South Indian tertiary eye care centre and were administered the AS-20 questionnaire.The AS-20 was translated and back translated into two Indian languages. The AS-20 and its two 10-item subscales – ‘psychosocial’ and ‘function’were assessed separately for fit to the Rasch model, including an assessment of the rating scale, unidimensionality (by principal components analysis), measurement precision by person separation reliability, PSR, targeting, and differential item functioning (DIF; notable > 1.0 logits).

Results

Response categories were not used as intended, thereby, required re-organization and reducing their number from 5 to 3. The AS-20 had adequate measurement precision (PSR = 0.87) but lacked unidimensionality; however, deletion of the six multi-dimensionality causing items and an additional three misfitting items resulted in 11-item unidimensional questionnaire (AS-11). Two items failed to satisfy the model expectations in the ‘psychosocial’ subscale and were deleted – resulting in an 8-item unidimensional scale with adequate PSR (0.81) and targeting (0.23 logits). One item misfit in the ‘function’ subscale and was deleted—resulting in a 9 item Rasch-revised unidimensional subscale with acceptable PSR (0.80) and targeting (0.97 logits).None of the items displayed notable DIF by age, gender and level of education.

Conclusions

The AS-11 and its two Rasch-revised subscales – 8-item psychosocial and 9-item function subscale may be more appropriate than the original AS-20 and its two 10-item subscales for use as unidimensional measures of HRQoL in adults with strabismus in India. Further work is required to establish the validity of the revised rating scale.

The impact of a better-seeing eye and a worse-seeing eye on vision-related quality of life

PURPOSE

Patients with eye diseases often have a better-seeing eye (BSE) and a worse-seeing eye (WSE). This review will carve out the current knowledge in which the relationship to BSEs and WSEs contributes to overall visual functioning and vision-related quality of life (VRQoL).

METHODS

Searches were from database inception to the current date. Terms used for the search were "better eye", "worse eye", "utility", "life quality", "quality of life", "VFQ-25", and "visual acuity".

RESULTS

There is a lack of a clear definition for BSE and WSE, and the used definitions are regularly dependent on the underlying eye disease. "BSE" and "WSE" can interact in terms of binocular inhibition or summation. Measured influences of the BSE and WSE on VRQoL are dependent on the underlying instrument used for the measurement. Several studies show impaired VRQoL if only one eye is affected from disease, with unimpaired vision of the BSE. VRQoL can improve significantly when treating the BSE and the WSE. In eye diseases with impairment of the central vision, there is a better correlation between the BSE and VRQoL. However, in eye diseases with peripheral vision impairment, eg, glaucoma, functional parameters of the WSE are better predictors for VRQoL.

CONCLUSION

The WSE appears to have a stronger influence on VRQoL than is generally assumed. This is especially the case if the underlying eye disease does not affect central vision but peripheral vision.

The patient health questionnaire-9: validation among patients with glaucoma

Background

Depression and anxiety are two common normal responses to a chronic disease such as glaucoma. This study analysed the measurement properties of the depression screening instrument - Patient Health Questionnaire-9 (PHQ-9) using Rasch analysis to determine if it can be used as a measure.

Methods

In this hospital-based cross-sectional study, the PHQ-9 was administered to primary glaucoma adults attending a glaucoma clinic of a tertiary eye care centre, South India. All patients underwent a comprehensive clinical evaluation. Patient demographics and sub-type of glaucoma were abstracted from the medical record. Rasch analysis was used to investigate the following properties of the PHQ-9: behaviour of the response categories, measurement precision (assessed using person separation reliability, PSR; minimum recommended value 0.80), unidimensionality (assessed using item fit [0.7–1.3] and principal components analysis of residuals), and targeting.

Results

198 patients (mean age ± standard deviation  = 59.83±12.34 years; 67% male) were included. The native PHQ-9 did not fit the Rasch model. The response categories showed disordered thresholds which became ordered after category reorganization. Measurement precision was below acceptable limits (0.62) and targeting was sub-optimal (−1.27 logits). Four items misfit that were deleted iteratively following which a set of five items fit the Rasch model. However measurement precision failed to improve and targeting worsened further (−1.62 logits).

Conclusions

The PHQ-9, in its present form, provides suboptimal assessment of depression in patients with glaucoma in India. Therefore, there is a need to develop a new depression instrument for our glaucoma population. A superior strategy would be to use the item bank for depression but this will also need to be validated in glaucoma patients before deciding its utility.

A new index to monitor central visual field progression in glaucoma

PURPOSE

The visual field index (VFI) summarizes global visual field (VF) data and was developed to monitor glaucoma progression using 24-2 and 30-2 strategies. We applied similar principles and statistical procedures to develop a new parameter, the central field index (CFI), to monitor 10-2 VF progression.

DESIGN

Retrospective cohort.

PARTICIPANTS

Glaucoma patients with paracentral defects seen on 24-2 perimetry and followed up with at least 5 10-2 VF tests.

METHODS

The CFI was developed by calculating age-corrected defect depth at test points obtained during 10-2 examinations. The sensitivities at these points were scored as percentages similar to the method described for the VFI: 100-[(|total deviation|/age-corrected normal threshold) × 100]. A weighting procedure was applied based on published estimates of the occipital cortical spatial magnification. For validation, we performed mixed linear model testing for the association between CFI rates of change (%/year) and known risk factors for glaucoma progression in a population with established glaucoma and at least 5 10-2 VF tests. To determine whether the CFI was affected by cataract, as is known to occur with mean deviation (MD), we conducted a pilot evaluation comparing rates of CFI change in 3 groups: (1) eyes with cataract, (2) pseudophakic eyes, and (3) eyes in which cataract surgery was performed in the middle of the series.

MAIN OUTCOME MEASURES

Rates of CFI and MD change.

RESULTS

Central field index values were calculated for 176 eyes of 142 patients. The mean rate of CFI change of the entire sample was -1.10%/year (95% confidence interval, -1.03 to -1.16%/year). Elevated intraocular pressure (P<0.001) was associated significantly with faster CFI change, whereas lens status did not influence CFI rates of change (P>0.100) CONCLUSIONS: We developed and validated a new index to monitor central field progression that is minimally affected by the presence or removal of cataract and that correlates significantly with an important risk factor for glaucoma progression. This new index may become useful for glaucoma management, especially when combined with conventional static perimetry strategies.

Quality assessment of ophthalmic questionnaires: review and recommendations

PURPOSE

The aim of this article was to systematically review all the available ophthalmic patient-reported outcome (PRO) instruments (questionnaires) that demonstrated interval measurement properties to identify the instruments with the highest psychometric quality for use in different eye diseases and conditions.

METHODS

An extensive literature review was carried out to identify all existing ophthalmic PRO instruments. Instruments were then excluded if they did not have demonstrable interval measurement properties; the remaining instruments were reviewed. The quality of the following psychometric properties was assessed: content development (initial item development process), performance of the response scale, dimensionality (whether the instrument measures a single construct), measurement precision, validity (convergent, concurrent, discriminant, and known groups), reliability (test-retest), targeting (whether the items are appropriate [e.g., difficulty level] for the population), differential item functioning (whether subgroups of people respond differently to an item), and responsiveness.

RESULTS

The search identified 48 PRO instruments that demonstrated interval measurement properties, and these were relevant to nine applications: glaucoma, dry eye, refractive errors, cataract, amblyopia and strabismus, macular diseases, adult low vision, children low vision, and others. These instruments were evaluated against the psychometric property quality criteria and were rated for quality based on the number of criteria met.

CONCLUSIONS

This review provides a descriptive catalog of ophthalmic PRO instruments to inform researchers and clinicians on the choice of the highest-quality PRO instrument suitable for their purpose.

The impact of structural and functional parameters in glaucoma patients on patient-reported visual functioning

BACKGROUND

To evaluate the impact of structural changes of the retinal nerve fiber layer (RNFL), and visual field loss, on functional impairment assessed by patient-reported visual functioning in glaucoma.

METHODS

Patients with glaucomatous optic nerve damage were enrolled in this cross-sectional study. Peripapillary RNFL thickness was obtained with spectral-domain optical coherence tomography (SD-OCT). Function was assessed by patient-reported visual functioning using the Rasch-calibrated Glaucoma Activity Limitation 9 (GAL-9) questionnaire and standard automated perimetry. The impact of peripapillary RNFL loss on functional impairment was analyzed with correlation and linear regression analyses.

RESULTS

A total of 176 eyes from 88 glaucoma patients were included. The SD-OCT assessed temporal-superior and temporal-inferior RNFL sector of the worse eye revealed significant correlation with the GAL-9 scores (r=-0.298, p=0.011 and r=-0.251, p=0.033, respectively). In mutivariate regression analysis, the best predictors for patient-reported visual functioning were visual acuity of the better eye and mean defect of the worse eye (R(2)=0.334), while structural parameters could not enhance the prediction of GAL-9 scores.

CONCLUSIONS

Self-reported visual functioning of patients with glaucoma is better predicted by visual performance data than structural parameters. However, some structural changes of the worse eye are significantly correlated with patient-reported visual functioning.