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Pinpoint pupils size3/31/2023 ![]() ![]() To measure the monocular reading performance achieved with different small pupils, we chose not to employ the typical optical telescope system that images a fixed AP into the subjects' pupil plane 34, 46 because of the significant eye movements associated with reading lines of text. 34, 39 – 41 Because small pupils lower retinal illuminance, which leads to decreased contrast sensitivity and visual acuity, there is concern that small pupils, although perhaps ideal for presbyopes at high photopic light levels, will compromise visual performance at low photopic or mesopic light levels. Also, computer modeling and visual acuity experiments both indicate that the pupil size required to maximize visual acuity becomes larger as light levels fall. Except at high photopic light levels, human spatial vision is considered to be photon limited, 36 – 38 and the elevated photon noise effects at lower light levels reduce contrast sensitivity. 23 However, at mesopic light levels, the gains in objective image quality for near targets, 34 near visual acuity, 34 and subjective near visual task satisfaction 23, 35 associated with pupil miosis are reduced. Photopically, small pupils have been shown to significantly expand the objective 26, 27 and subjective 30, 31 depth of focus, distance, 24, 25, 29, 32 and near visual acuity 24, 25, 29, 33 and reading performance. The 2- to 3-mm artificial pupils and the multifocal contact lenses both enabled maximum or near-maximum reading speeds for 0.5 logMAR characters at distance and near, but with natural pupils, reading speeds were significantly reduced at near.Īlthough photon noise at low luminance reduces the visual benefits of small pupils, the benefits of 2- to 3-mm artificial pupils are sufficient to enable >80% of distance-corrected presbyopes to read proficiently at near, even at the lowest text luminances found in interior environments. For both distance and near reading performance, the 2- to 3-mm small pupil yielded the best overall reading acuity for space-averaged text light levels ≥ 2 cd/m 2. ![]() Space-averaged text luminance levels varied from 0.14 to 140 cd/m 2 (including the range of measured environmental text luminances).Īdding black text to a white computer display or paper reduces luminance by approximately 15% to 31%, and the lowest encountered environmental text luminance was approximately 2 to 3 cd/m 2. Distance and near reading speeds of 20 presbyopes (ages 40–60 years) were measured while viewing through artificial pupils (diameters 1–4.5 mm), natural pupils, or with a multifocal contact lens. To establish the lower range of text luminances, we quantified the space-averaged luminance of text in nine different artificially lit interior environments, and examined the impact of the text characters on space-averaged luminance of electronic and printed displays. To determine whether small pupils would enable presbyopes to read at near even at low light levels. To examine the impact of small pupils and light levels on reading performance of distance-corrected presbyopes.
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