ENHANCEMENT OF TEXT FOR THE VISUALLY-IMPAIRED

Previous research has established the benefits of image enhancement by spatial filtering for face perception and motion video appreciation a mong elderly low-vision observers [Invest. Ophthalmol. Vis, Sci. 32, 2 337 (1991); J. Opt. Sec, Am, A 11, 1929 (1994)]. It has also been repo rted that similar enhancement could increase reading speeds by a facto r of 2-4 in the same population [cf. Ophthalmology 96, 115 (1989)]. In our experiments we sought to determine what benefit, if any, was deri ved from spatial filtering of text for low-vision readers. Results fro m this series of studies indicate that 66% of patients do increase the ir reading rate with enhancement, but this increase is small. Change i n reading rate with spatial filtering ranged from a 100% decrement to a 125% improvement, with an average 13% improvement. Only 10 of 67 sub jects increased their reading rates by 50% or more. The clinical infor mation that we gathered does not allow us to predict accurately which patients will benefit from spatial filtering. On the basis of these fi ndings we conclude that enhancement of text by spatial filtering does not substantially increase reading rates for most low-vision patients.