Purpose: Reading is one of many daily-life activities that is severely impaired in individuals with central field loss (CFL). Standard reading tests like MNREAD or SKRead charts are widely used to quantify reading deficits in these individuals. Micro-perimeters allow visualization of the retinal region used for reading, but it is unclear whether patients use the same retinal locus to read in free space. This study compared reading performance using handheld MNREAD charts to that for MNREAD-like sentences presented in a NIDEK MP-1 micro-perimeter.
Methods: Reading performance was assessed in the better eye of 16 subjects (age: 20-84 years) with bilateral CFL, using (1) MNREAD charts held at an appropriate distance (range 12 – 40 cm) in a well-lit room and (2) MNREAD-like sentences loaded as bitmap images and presented on a uniform white LCD display (LBackground=127 cd/m2) in a NIDEK MP-1 micro-perimeter. Time taken to read each sentence was recorded, from which reading speed was calculated in words per minute (wpm). Reading acuity (RA) was calculated from the smallest sentence that subjects could read. Testing using MNREAD charts was always done before the MP-1. Each reading assessment was performed twice, and average peak reading speed and RA were computed.
Results:MNREAD and MP-1 peak reading speeds and RAs were highly correlated (r = +0.87 and +0.89 respectively). The mean differences between the MNREAD-chart and MP-1 results were 4±28 wpm and -0.02±0.11 logMAR for peak reading speed and RA, respectively. Limits of agreement determined from Bland-Altman analysis were -51 to +59 wpm and -0.23 to +0.20 logMAR respectively for peak reading speed and RA.
Conclusions: The MP-1 microperimeter can be used to reliably assess reading performance in subjects with CFL. The MP-1 reading measures agree well with those from MNREAD cards, suggesting a similar preferred retinal loci was used during both forms of testing.