Abstract
Purpose: :
To assess reading performance related to scotoma characteristics through the administration of MNRead and Smith-Kettlewell Reading Test (SKRead) in Italian.
Methods: :
52 eyes/38 patients with AMD and reading difficulties were referred to two Low Vision Centers in Italy and evaluated through ETDRS visual acuity (VA ) at 1 and 2 meters, Pelli-Robson Contrast Sensitivity (CS), MNRead, SKRead, and California Central Visual Field Test (CCVFT). SKRead shares the same 60 characters block structure as the MNRead but differs in the fact that words and letters are randomly arranged, thus avoiding cognitive anticipation of words from context. Reading rates and errors and were recorded. The latter were classified as right, left or other, as they occurred on the side of a word or within it. Central scotomas were searched with the CCVFT. A dense scotoma (DS) was defined when a spot laser light of 3 mm at 57 cm (0.3 deg) was not seen, while a relative scotoma (RS) defined when a 1 mm spot light (0.1 deg) was not seen. Scotoma presence and location within 5 degrees of fixation point were recorded. Eyes unable to read any word on either MNRead or SKRead were excluded. Controls were 45 eyes/45 subjects with no sign of AMD or diseases affecting reading, no central scotoma, and VA >20/40.
Results: :
Cases characteristics median (range) were age 78 (95-55), VA 20/101 (/30-962), CS 1.05 (1.35-0). A condition of DS was detected in 30/52 eyes, RS in 11/22 eyes with no evidence of DS, and no scotoma in the remaining 11 eyes. On SKRead, sentences read median (range) was 9 (10-1), errors 10 (33-0), Reading Rate Max (RRMax) 13.3 (133-6 seconds), Reading Rate Min (RRMinn) 29.1 (133-10.8). On MNRead, sentences median (range) was 9 (10-1), errors 2 (9-0), RRMax 5 (120-2.7), RRMin 19.3 (120-4.2). Controls age median (range) was 76 (89-53), VA 20/20 (/20-30), CS 1.35 (1.65-0.9), sentences 10 (10-9) on both SKRead and MNRead, errors 5 (35-3) on SKRead, and 0 (4-1) on MNRead. Sentences read on SKRead, but not on MNRead, was strongly associated (p<0.05) with VA, CS, and presence of a DS, especially a scotoma on the right side. SKRead was also strongly associated with a central scotoma as reading rates decreased and errors increased significantly (p<0.05).
Conclusions: :
SKRead was useful to define visual skills for reading related to central scotomas, which were outlined at the CCVFT. Controls made typical repetitive errors compared to patients with vision loss.
Keywords: low vision • age-related macular degeneration • reading