Validity and reliability of the Children's Visual Function Questionnaire (CVFQ)

Abstract

Purpose: The Children's Visual Function Questionnaire (CVFQ) is a vision-specific quality-of-life instrument designed for use with children up to 7 years of age. The goal of this study was to assess the construct validity of CVFQ subscales by examining their sensitivity to four research questions commonly posed in ophthalmic clinical trials.

Methods: CVFQ Competence, Personality, Family Impact, and Treatment Difficulty subscale scores were compared for groups of pediatric patients with unilateral versus bilateral disease (35 bilateral and 38 unilateral cataract), different severity of visual impairment (61 retinopathy of prematurity [ROP] grouped by acuity), difficulty of treatment regimen (22 optical, 44 surgery, 38 surgery with optical, and 35 surgery with optical and occlusion), and alternative treatments for the same condition (24 intraocular lenses, 37 aphakic contact lenses).

Results: Patients treated for bilateral cataracts had significantly worse Competence subscale scores than patients treated for unilateral cataract, and patients with bilateral severe ROP (visual acuity 20/200 or poorer in both eyes) had significantly worse Competence subscale scores than other patients with ROP. Treatment Difficulty subscale scores were worse for patients with unilateral cataracts than for those with bilateral cataracts, worse for patients treated with occlusion therapy than for those treated with surgery or optical correction, and worse for those treated with an aphakic contact lens than for those treated with an intraocular lens. Family Impact subscale scores were worse for patients with unilateral cataracts than for those with bilateral cataracts, worse for patients treated with surgery than for those treated with optical correction, and worse for those with severe bilateral ROP than for any other patients with ROP.

Conclusions: The CVFQ subscales quantified meaningful differences among pediatric patient groups who were chosen to address key research questions commonly posed in ophthalmic clinical trials.

Figure 1

CVFQ subscale scores (mean ± standard error) for pediatric patients treated for visually significant bilateral (n=35) or unilateral cataracts (n=38). Asterisks indicate pairwise comparisons that were significant on post-hoc Scheffé tests.

Figure 2

CVFQ subscale scores (mean ± standard error) for pediatric patients age 3 to 7 years with regressed or cicatricial retinopathy of prematurity and acuity of 20/200 or poorer in both eyes (n=11), 20/200 or poorer in one eye and 20/50-20/125 in the fellow eye (n=10), 20/50-20/125 in both eyes (n=8), 20/50-20/125 in one eye and 20/20-20/40 in the fellow eye (n=10), or 20/20-20/40 in both eyes (n=22). Bars with different superscripts are significantly different from each other.

Figure 3

CVFQ subscale scores (mean ± standard error) as a function of difficulty of treatment regimen, including optical correction (n=22), surgery (n=44), surgery and optical correction (n=38), and surgery, optical correction, and occlusion therapy (n=35). Bars with different superscripts are significantly different from each other.

Figure 4

Treatment Difficulty subscale scores for patients who were being treated with occlusion therapy at the time of the visit on which the CVFQ was completed. Patients are grouped by whether they were being treated for amblyopia or not (some patients with equal acuity in both eyes were occluded to wean from amblyopia treatment or to prevent amblyopia). Some patients are represented in more than one age group. The number of patients contributing to each data point (mean and standard error) ranges from 9 to 39.

Figure 5

CVFQ subscale scores (mean ± standard error) for pediatric patients treated for visually significant unilateral cataracts and were optically corrected using an IOL (pseudophakic; n=24) or an aphakic contact lens (aphakic CL; n=37). Asterisks indicate pairwise comparisons that were significant on post-hoc Scheffé tests.

Figure 6

Test-retest reliability for three subscale s of the CVFQ. The difference in subscale score on two questionnaires administered with 6 months (with no change in visual acuity category in either eye) is plotted as a function of the mean subscale score for both questionnaires.

Figure 7

Changes in Treatment Difficulty subscale scores for patients whose parents completed the questionnaire on two occasions, including children who had no change in treatment between the two tests (n=49), those who started occlusion therapy after the first questionnaire (n=16), those who stopped occlusion therapy after the first questionnaire (n=22), those who started atropine penalization after the first questionnaire (n=6), those who switched from occlusion therapy to atropine penalization after the first questionnaire (n=6), those who started glasses wear after the first questionnaire (n=19), those who stopped glasses wear after the first questionnaire (n=8), and those who switched from an aphakic contact lens to an IOL after the first questionnaire (n=8). Increased treatment difficulty is downward and less treatment difficulty is upward. Asterisks indicate differences scores that are significantly different from zero.