A Performance based test to assess activities of daily living in Glaucoma patients and its Correlation with Self-Reported Questionnaire

Abstract

Background: Glaucoma is a group of diseases characterized by loss of retinal nerve fibre layer and visual field loss1. Glaucoma is the commonest cause of irreversible blindness worldwide and the second leading cause of blindness worldwide after cataract2. In Nigeria, it remains the leading cause of irreversible blindness accounting for 16.7% of blindness among individuals aged 40 years and above3. Progressive vision loss from glaucoma has significant impact on quality of life4. This has been assessed using subjective methods in form of questionnaires but physical performance-based assessment may offer several advantages over self-reported questionnaires5. Previous studies in Nigeria reported reduced quality of life in glaucoma patients using self-reported questionnaire6,7. The aim of this study was to assess the quality of life in primary open angle glaucoma patients using both subjective (National Eye Institute Visual Function Questionnaire-25) and objective tests (Compressed Assessment of Ability Related to Vision (CAARV)) and to examine correlation between both methods.

Methods: This was a cross sectional study of adult Primary Open Angle Glaucoma (POAG) patients on medical therapy at the Guinness Eye Centre, Onitsha Nigeria between January to May 2019. The patients were selected by systematic sampling technique. Patients responded to questions on sociodemographics and completed the National Eye Institute Visual Function Questionnaire-25(NEIVFQ-25)8. All patients also completed the Compressed Assessment of Ability Related to Vision (CAARV)9, which is a performance-based test with four items including motion detection, recognizing facial expression, reading street sign and finding objects in a room. Ocular examination and central visual field test using automated perimetry were also done.

Results: One hundred and seventy-one patients, aged 40-83 years, (mean 59.1±11.1) were studied; there were 79(46.2%) males and 92(53.8%) females. The scores of the Compressed Ability to Perform Activities Related to Vision are shown in Table 1. The mean CAARV total score was 24.64±5.27. The mean NEI-VFQ25 score was 83.2±19.30. CAARV correlated significantly with NEI-VFQ scores (r=0.679, p<0.001). Both CAARV and NEI-VFQ-25 correlated significantly with visual acuity and visual fields of both better and worse eye. CAARV was more strongly correlated with better eye visual acuity as shown in Figure 1.

Discussion: The results of this study demonstrated reduced quality of life in glaucoma patients using self-reported questionnaire (NEI VFQ-25 ) and performance-based test(CAARV).The mean vision-related quality of life measured with
NEI-VFQ-25 was similar to the 85.2 obtained by Onakoya et al6 in Lagos among primary open angle glaucoma patients. The slightly higher value in the Lagos study may be explained by the higher proportion of patients with post-secondary education in their study population (49.3%). Both Wei et al9 and Ezenwa& Nwosu10 reported reduced performance scores in glaucoma patients using CAARV and Assessment of Disability Related to Vision (ADREV) respectively. Wei et al9 recorded CAARV scores of 20.63 with lowest scores in facial expression and highest scores in motion detection and this is similar to our findings. Performance scores recorded with CAARV correlated moderately with quality of life scores in this study. This implies that a patient may overreport or under-report his/her difficulties while responding to questions in the NEI-VFQ-25. Hence combining both tests in clinical practice may give a better understanding of the patient’s disabilities.

Conclusion: Performance based test objectively tests a patient’s actual ability to perform a given task. Although these tests were carried out in a hospital setting, they tried to simulate the patient’s environment. This study showed a significant correlation between CAARV (a performance-based test) and self-reported quality of life with a stronger correlation between CAARV and visual acuity. Further studies may be required to justify the inclusion of a performance-based test in clinical practice to complement self-reported quality of life assessment.