Table 3:
ANCOVA comparing VSQOL scores across VFL severity categories adjusting for covariates
| Vision-Specific Quality of Life Measures Adjusted Mean Scores (SE)* | Visual Field Loss Severity
Categories (n = 4,207)‡ |
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| No VFL (n = 2,348) | Unilateral | Bilateral | P-Value§ | ||||||||
| Mild (n = 848) | Moderate to Severe (n = 92) | Mild (n = 792) | Moderate to Severe (n = 127) | ||||||||
|
| |||||||||||
| NEI-VFQ-25 | |||||||||||
| Item Response Theory | |||||||||||
| IRT Task Composite† | 86.8 | (0.3)a | 84.3 | (0.6)b | 84.9 | (1.7)a,b | 82.5 | (0.6)b | 76.9 | (1.5)c | < 0.001 |
| IRT Well-Being Composite‡ | 76.9 | (0.3)a | 75.2 | (0.5)b | 73.4 | (1.4)a,b,c | 73.5 | (0.5)c | 70.7 | (1.2)d | < 0.001 |
| Classical Test Theory | |||||||||||
| CTT Composite§ | 94.7 | (0.1)a | 93.7 | (0.2)b | 93.7 | (0.6)a,b | 93.0 | (0.2)b | 90.7 | (0.6)c | < 0.001 |
| Driving Difficulties∥ | 95.7 | (0.3)a | 93.5 | (0.4)b | 95.3 | (1.3)a,b | 93.0 | (0.5)b | 85.0 | (1.3)c | < 0.001 |
| General Vision | 75.1 | (0.3)a | 73.0 | (0.5)b | 71.7 | (1.5)a,b,c | 70.4 | (0.5)c | 68.6 | (1.3)d | < 0.001 |
| Near Vision | 95.2 | (0.2)a | 93.9 | (0.4)a,b | 94.3 | (1.1)a,b | 92.7 | (0.4)b | 90.2 | (0.9)c | < 0.001 |
| Vision-Related Mental Health | 91.4 | (0.2)a | 89.9 | (0.4)a,b | 89.1 | (1.2)a,b | 89.0 | (0.4)b | 86.4 | (1.0)c | < 0.001 |
| Peripheral Vision | 98.1 | (0.2)a | 96.9 | (0.3)b | 96.5 | (0.9)a,b | 96.6 | (0.3)b | 94.1 | (0.8)c | < 0.001 |
| Distance Vision | 97.4 | (0.2)a | 96.7 | (0.3)a,b | 96.9 | (0.9)a,b | 95.8 | (0.3)b | 93.5 | (0.8)c | < 0.001 |
| Vision-Related Role Function | 96.9 | (0.3)a | 96.2 | (0.4)a | 95.8 | (1.3)a | 95.8 | (0.5)a | 93.0 | (1.1)b | 0.010 |
| Vision-Related Dependency | 99.1 | (0.2)a | 98.4 | (0.3)a | 98.9 | (0.8)a | 98.1 | (0.3)a | 96.7 | (0.7)b | 0.001 |
| Vision-Related Social Function | 99.2 | (0.1)a | 98.6 | (0.2)a | 98.5 | (0.6)a | 98.5 | (0.2)a | 97.8 | (0.5)b | < 0.001 |
| Ocular Pain | 94.9 | (0.2)a | 94.3 | (0.4)a | 94.8 | (1.2)a | 93.9 | (0.4)a | 92.6 | (1.0)b | 0.058 |
| Color Vision | 99.2 | (0.1)a | 99.1 | (0.2)a | 99.5 | (0.6)a | 99.1 | (0.2)a | 98.9 | (0.5)b | 0.872 |
| General Health Item | |||||||||||
| General Health | 58.3 | (0.4)a | 56.5 | (0.7)a,b | 55.1 | (2.2)a,b,c | 55.0 | (0.8)b,c | 52.1 | (1.9)c | < 0.001 |
| SF-12 | |||||||||||
| Mental Component Score | 60.5 | (0.1)a | 59.7 | (0.2)a,b | 60.8 | (0.6)a,b | 59.9 | (0.2)b | 60.4 | (0.6)a,b | 0.008 |
| Physical Component Score | 39.8 | (0.1)a | 39.9 | (0.1)a | 39.8 | (0.5)a | 39.9 | (0.2)a | 39.0 | (0.4)a | 0.334 |
ANCOVA = analysis of covariance; VSQOL = Vision-Specific Quality of Life; VFL = Visual Field Loss; AFEDS = African American Eye Disease Study; NEI-VFQ-25 = National Eye Institute Visual Function Questionnaire 25-Item; IRT = Item Response Theory; CTT = Classical Test Theory; SF-12 = 12-Item Short-Form Health Survey; MD = Mean Deviation
Adjusted mean (standard error) NEI-VFQ-25 and SF-12 scores. The covariates for adjustment include age, gender, education, employment status, income, comorbidities, health insurance, vision insurance, and presenting visual acuity 20/40 or worse.
VFL was classified as none (MD > −2), unilateral mild VFL (−6 ≤ MD ≤ −2 in the worse eye), unilateral moderate-to-severe VFL (MD < −6 in one eye, MD > −2 in the other eye), bilateral mild VFL (−6 ≤ MD ≤ −2 in both eyes, or −6 ≥ MD ≥ −2 in one eye, MD < −6 in the other eye), bilateral moderate-to-severe VFL (MD < −6 in the both eyes).
Analysis of covariance was used to compare adjusted mean scores across the different levels of unilateral and bilateral VFL. The P-value corresponds to the ANCOVA type III sums of squares f-test across the VFL groups. For each row, means with different letters (a–d) across the VFL categories are statistically significantly different from one another after adjusting for multiple comparisons using the Tukey-Kramer method (p < 0.05). ANCOVA revealed significant differences across the VFL categories for all VSQOL scales except ocular pain, color vision, and the physical component score of the SF-12.
Composite score is an un-weighted mean of 11 of the 12 NEI-VFQ-25 subscale scores (except general health).
Scores could be generated for only 3,808 of the participants who reported that they were currently driving or had driven in the past; the sample size was 2,199, 760, 84, 672, and 93 for the five VFL categories, respectively.
IRT Task Composite was calculated from a graded response model of 13 items from near vision, distance vision, driving, color vision, peripheral vision, and role difficulties subscales.
IRT Well-Being Composite was calculated from a graded response model of 12 items from general vision, dependency on others, mental health, ocular pain, and social functioning subscales.