Abstract
Purpose::
To compare error patterns of low vision patients on the MN Read and the SK Read relative to SLO determined scotomas and PRL characteristics.
Methods::
Better seeing eyes of 111 patients had reading performance (MN Read, SK Read), visual acuity, and macular function (SLO) testing performed at initial presentation to a low vision rehab clinic. The SK Read uses random words and letters in a sentence block structure (similar to MN Read) offering meaningful words with right or left omission/substitution of letters and impedes cognitive correction of errors (similar to Pepper Test). Errors on the words of the reading tests were categorized as right, left or neither. Patients were grouped on SLO scotomas relative to the PRL as no horizontal (N) n=43, right (R) n=32, left (L) n=16 or right and left (RL) n=20. PRL location was classified as either fovea or eccentric.
Results::
Age median (range) was 82 (13-97). Visual acuity median (range) was 20/116 (20/40-730). 33% of patients made no mistakes on MN Read while only 3% made no mistakes on SK Read (errors/blocks: MN Read = 0.21, SK Read = 1.51). Right and left sided errors showed high correlation with SLO demonstrated righ/left horizontal scotoma characteristics especially on SK Read (Tukey-Kramer HSD p<.0001). MN Right/Left errors vs scotoma group are R=1.4/0.1, RL=0.6/0.5, L=0.1/1.1, N=0.1/0.1. SK Right/Left errors vs scotoma group are R=7.0/0.3, RL=3.7/2.2, L=1.0/6.3, N=0.7/0.5. Horizontal size of scotoma and PRL to fovea distance were much more highly associated with performance on both MN Read and SK Read than either visual acuity or age. On the SK Read omission type errors were uncommon without the presence of a scotoma and increased further if the PRL was eccentric.
Conclusions::
In low vision patients errors are far more common on the SK Read and of special interest, R/L type of errors. The R/L pattern of errors on the SK Read were closely correlated with SLO determined scotomas/PRL characteristics. Knowledge of patient error patterns on this simple test may provide valuable information to those planning rehabilitation interventions.
Keywords: low vision • reading • visual fields