Rasch analysis of Impact of Vision Impairment for Children questionnaire

Beyond Intraocular Pressure: Visual Functioning and Quality of Life in Primary Congenital Glaucoma and Secondary Childhood Glaucoma

PURPOSE

To compare the visual functioning (VF) and vision-related QoL (VRQoL) of children 8-18 years old treated for primary congenital glaucoma (PCG) and secondary childhood glaucoma.

DESIGN

Cross-sectional study.

METHODS

A total of 309 children 8-18 years old treated for PCG and secondary childhood glaucoma between 2000 and 2010 by a single pediatric glaucoma specialist were prospectively enrolled at LV Prasad Eye Institute, Hyderabad, India. Children completed 2 questionnaires, the LV Prasad Functional Vision Questionnaire-II (LVP-FVQ-II), and the Impact of Vision Impairment-Children (IVI-C) questionnaire. Rasch-calibrated scores from both these questionnaires were used to compare the VF and VFQoL between the 2 groups.

RESULTS

Mean ages of the children were 12.2 and 12.6 years in the PCG (53%, median age at diagnosis = 5 months) and secondary glaucoma groups (47%, median age at diagnosis = 3 years), respectively. A majority (80%) of children had bilateral glaucoma and underwent filtering surgery (83%). Mean better eye logMAR visual acuity (VA) was comparable between PCG and secondary childhood glaucoma groups (0.49 vs 0.52, respectively; P = 0.59). Children with PCG reported significantly better VF and VRQoL than secondary childhood glaucoma patients. Unadjusted and adjusted childhood glaucoma group comparisons revealed secondary childhood glaucoma to be associated with worse VF and VRQoL compared to PCG (difference for VF, -0.83; 95% confidence interval [CI], -1.34 to 0.31; P = 0.002; 0.39; 95% CI, 0.16-0.62; P = 0.001 for VRQoL).

CONCLUSIONS

Results show that children with treated PCG experience significantly better VF and VRQoL than those with secondary childhood glaucoma, despite comparable VA and IOP.

Randomized Trial of Tablet Computers for Education and Learning in Children and Young People with Low Vision

SIGNIFICANCE

Mobile devices such as tablet computers have become widely available as mainstream devices and are also used in some schools, but there is an absence of robust information regarding the efficacy of any optical/electronic low vision device or tablet computer in supporting education of young people with low vision.

PURPOSE

A randomized controlled trial (RCT) is needed to measure the impact of tablet computers on education, specifically on independent access to educational material, in children and young people with low vision. We conducted a pilot RCT to determine the feasibility of conducting a full-scale trial.

METHODS

This was a randomized multicenter pilot trial across two sites in the United Kingdom and one site in India. Forty children and young people aged 10 to 18 years with low vision (best-corrected visual acuity for distance between <20/60 [0.48 logMAR] and 20/400 [1.30 logMAR] in the better eye) in the United Kingdom (n = 20) and India (n = 20) were randomized to two parallel arms, with a 1:1 allocation ratio, to control (n = 20) or intervention (n = 20). Control group participants received standard low vision care. The intervention group received a tablet computer (iPad) with low vision applications and instruction in its use, including accessibility features. Four primary outcomes included (1) 6-month recruitment rate, (2) retention of participants for 3 months, (3) acceptance/usage of device, and (4) accessibility of device.

RESULTS

Nineteen participants (95%) enrolled within 6 months in the United Kingdom, and 20 participants (100%), in India. Retention at 3 months was 85% (n = 17) in the United Kingdom and 95% (n = 19) in India. More than one half of participants reported using a tablet computer at school at least once every day. The majority (90%) found it easily accessible.

CONCLUSIONS

This study demonstrated that it is feasible to recruit children and young people with low vision into an international multicenter RCT of electronic assistive technology. Regardless of geographical location, children and young people with low vision reported using tablet computers at least once a day at school and accessed them easily.

Quality of life following surgery for congenital glaucoma: findings of the LVPEI congenital glaucoma registry

PURPOSE

To evaluate the health-related quality of life (HRQoL) of children operated for primary congenital glaucoma (PCG) using the Kidscreen-27 questionnaire.

METHODS

A total of 121 children (mean age, 11.8 years; SD, 2.8 years; 51% males) with unilateral or bilateral PCG who underwent glaucoma surgery in infancy (mean duration since surgery, 10.2 years; [SD] 4.2 years) by a single surgeon at a tertiary eye care centre were administered the Kidscreen-27 questionnaire (self-or interviewer administered in a face-to-face interview) during their routine follow-up visit. We investigated the measurement properties of Kidscreen-27 questionnaire using Rasch analysis and generated interval-level estimates of HRQoL. The main outcome measure was HRQoL (i.e., Rasch-derived Kidscreen score). Multivariable linear regression analyses assessed the influence of socio-demographic and clinical variables on the HRQoL of children with PCG.

RESULTS

Majority (83%) of the children had bilateral PCG and congenital type of the disease (79%). Mean presenting acuity (logMAR) in the better eye was 0.32 (SD, 0.36; median, 0.18). Rasch analysis of Kidscreen-27 questionnaire indicated need for minor modifications following which a psychometrically robust unidimensional 23-item Kidscreen questionnaire emerged. In multivariable model, age of the child was independently associated with a 32% (β = -0.24 [95% CI, -0.11, -0.36]) increase in the HRQoL score.

CONCLUSIONS

Despite undergoing successful glaucoma surgery, children with PCG reported reduced HRQoL. Younger children with PCG are more likely to experience this lowered HRQoL and ophthalmologists will need to be alert to this. Efforts must be made to improve the HRQoL of children with PCG.

Validation of an instrument to assess visual ability in children with visual impairment in China

OBJECTIVE

To validate a visual ability instrument for school-aged children with visual impairment in China by translating, culturally adopting and Rasch scaling the Cardiff Visual Ability Questionnaire for Children (CVAQC).

METHODS

The 25-item CVAQC was translated into Mandarin using a standard protocol. The translated version (CVAQC-CN) was subjected to cognitive testing to ensure a proper cultural adaptation of its content. Then, the CVAQC-CN was interviewer-administered to 114 school-aged children and young people with visual impairment. Rasch analysis was carried out to assess its psychometric properties. The correlation between the CVAQC-CN visual ability scores and clinical measure of vision (visual acuity; VA and contrast sensitivity, CS) were assessed using Spearman's r.

RESULTS

Based on cultural adaptation exercise, cognitive testing, missing data and Rasch metrics-based iterative item removal, three items were removed from the original 25. The 22-item CVAQC-CN demonstrated excellent measurement precision (person separation index, 3.08), content validity (item separation, 10.09) and item reliability (0.99). Moreover, the CVAQC-CN was unidimensional and had no item bias. The person-item map indicated good targeting of item difficulty to person ability. The CVAQC-CN had moderate correlations between CS (-0.53, p<0.00001) and VA (0.726, p<0.00001), respectively, indicating its validity.

CONCLUSIONS

The 22-item CVAQC-CN is a psychometrically robust and valid instrument to measure visual ability in children with visual impairment in China. The instrument can be used as a clinical and research outcome measure to assess the change in visual ability after low vision rehabilitation intervention.

Rasch analysis of the Student Refractive Error and Eyeglass Questionnaire

PURPOSE

To evaluate and refine a newly developed instrument, the Student Refractive Error and Eyeglasses Questionnaire (SREEQ), designed to measure the impact of uncorrected and corrected refractive error on vision-related quality of life (VRQoL) in school-aged children.

METHODS

A 38-statement instrument consisting of two parts was developed: part A relates to perceptions regarding uncorrected vision and part B relates to perceptions regarding corrected vision and includes other statements regarding VRQoL with spectacle correction. The SREEQ was administered to 200 Native American 6th- through 12th-grade students known to have previously worn and who currently require eyeglasses. Rasch analysis was conducted to evaluate the functioning of the SREEQ. Statements on parts A and B were analyzed to examine the dimensionality and constructs of the questionnaire, how well the items functioned, and the appropriateness of the response scale used.

RESULTS

Rasch analysis suggested two items be eliminated and the measurement scale for matching items be reduced from a four-point response scale to a three-point response scale. With these modifications, categorical data were converted to interval-level data to conduct an item and person analysis. A shortened version of the SREEQ was constructed with these modifications, the SREEQ-R, which included the statements that were able to capture changes in VRQoL associated with spectacle wear for those with significant refractive error in our study population.

CONCLUSIONS

Although part B of the SREEQ appears to have a less-than-optimal reliability to assess the impact of spectacle correction on VRQoL in our student population, it is able to detect statistically significant differences from pretest to posttest on both the group and individual levels to show that the instrument can assess the impact that glasses have on VRQoL. Further modifications to the questionnaire, such as those included in the SREEQ-R, could enhance its functionality.