The reading accessibility index and quality of reading grid of patients with central vision loss

Abstract

Purpose: In this study we evaluated the reading accessibility index (ACC) and a quality of reading grid as assessment tools for reading and as outcome measures for reading rehabilitation of patients with central vision loss.

Methods: Reading performances on the MNRead chart (www.precision-vision.com) were reviewed from our research database. Participants were 24 controls with normal vision [mean age: 34 (SD, 14) years] and 61 patients with bilateral central vision loss [mean age: 81 (SD, 9) years] among which a subgroup of 18 patients [mean age, 76 (SD, 13) years] had undergone perceptual learning training for reading rehabilitation. The outcome measures were maximum reading speed, reading acuity, critical print size, ACC, and the reading quality. A reading quality grid that classified reading speed as spot, slow, functional, or fluent and print size as small, regular, medium, or large was used. All reading speed values were normalised (i.e., divided by 200, the average reading speed in young adults with normal vision measured with the MNRead).

Results: The ACC was associated perfectly with the maximum reading speed in the control group (r₂₂ = 0.99, P < 0.001) and strongly with all parameters of reading in the patient group (smallest r value: r₅₉ = -0.66, P < 0.001). For patients with central vision loss, reading was functional for large print, but slow for medium print and spot for regular print. For some patients with the same ACC values, the quality of reading grid revealed important performance differences. For the subgroup (n = 18) of patients who were trained, the ACC revealed a greater effect of training than the other three parameters of reading, and although there were statistically significant improvements across all print size categories, a qualitative improvement in reading was noticed only for the medium print sizes.

Conclusions: The ACC is a good measure of reading performance in patients with central vision loss. Examining reading quality for different print size categories can provide a more detailed picture of reading impairment and should be considered as an outcome for rehabilitation in addition to the ACC.

Keywords: central vision loss; low vision; macular degeneration; reading; reading impairment.