Psychometric properties of the national eye institute refractive error correction quality-of-life questionnaire among Iranian patients

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Date: January-April 2013
From: Oman Journal of Ophthalmology(Vol. 6, Issue 1)
Publisher: Medknow Publications and Media Pvt. Ltd.
Document Type: Article
Length: 4,049 words
Lexile Measure: 1490L

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Byline: Amir. Pakpour, Isa. Zeidi, Mohsen. Saffari, Georgios. Labiris, Bengt. Fridlund

Background and Aim: To evaluate the psychometric properties of the national Eye Institute refractive error correction quality of life questionnaire (NEI-RQL-42) among Iranian patients with refractive errors. Materials and Methods: Two samples of patients (n1 = 296, n2 = 95) were consecutively selected from the eye clinic of the Boo-Ali Hospital, Qazvin. A forward-backward procedure was conducted to translate and cross-culturally adapt the Iranian version of the NEI-RQL-42. A homogeneity, stability, and reliability test was conducted for the first sample after a two-week interval. Convergent validity was computed using the correlation between the NEI-RQL-42 subscale scores, National Eye Institute-Visual Functioning Questionnaire (NEI-VFQ-25), and the Short Form-36 (SF-36). Furthermore, Known-group analysis was performed, to determine the discriminant validity between the subgroups of patients with hyperopia, emmetropia, and myopia. Responsiveness to clinical change was tested by administering NEI-RQL-42 on the second sample that was scheduled for surgery. Results: Homogeneity was satisfactory with the Cronbach's alpha coefficients ranging between 0.70 and 0.92. The 13 subscales of the NEI-RQL-42 showed a considerable stability in intra-class-correlation (ICC) ranging between 0.70 and 0.89. Positive correlation coefficients were found among all subscales of the NEI-RQL-42 and the other quality-of-life instruments (NEI-VFQ-25 and SF-36). The NEI-VFQ-25 displayed excellent discriminant validity to differentiate the subgroups of patients, and was found to be responsive to change after the surgical correction at three months. Conclusions: The Iranian version of the NEI-RQL-42 is a valid and reliable instrument to assess refractive error correction quality-of-life in Iranian patients. Moreover this questionnaire can be used to evaluate the effectiveness of interventions in patients with refractive errors.

Introduction

It is known that refractive errors are associated with about 43% of the causes related to visual impairment. [sup][1],[2] The simplified approach of refractive errors indicates four primary types: Myopia (nearsightedness), Hyperopia (farsightedness), Presbyopia (abnormal close-up focusing due to aging), and Astigmatism (abnormal focusing due to irregular shape of cornea). [sup][3] According to the World Health Organization (WHO) reports, there are approximately 153 million people around the world living with visual impairment due to uncorrected refractive errors. [sup][4] Insufficient management of refractive errors in developing countries could result in reversible blindness. [sup][5],[6] A recently published Iranian study demonstrated that uncorrected refractive errors accounted for about 64% of the most prevalent causes of visual disorder among middle-aged people. [sup][7]

It is recognized that visual impairments due to refractive errors significantly affect the vision-specific quality of life and prospectively lead to reduced productivity. [sup][8],[9] They can also contribute to psychological disorders such as depression. [sup][10],[11] In fact the exploration of the impact of refractive disorders requires, further to traditional clinical indexes like visual acuity, the assessment of contemporary indexes that reflect the subjective perception of visual capacity. Among the prevalent instruments that evaluate quality of life and visual capacity, one is the National Eye Institute Refractive Error Quality of Life Questionnaire (NEI-RQL-42), originally developed for the American English-speaking populations. [sup][11],[12] It is a disease-specific questionnaire that is prevalently...

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Gale Document Number: GALE|A331849591