Abstract
Purpose :
Many activities of daily living rely on reading, thus is not surprising that complaints from presbyopes originate in reading difficulties rather in visual acuity. Here the effectiveness of presbyopia correction with multifocal contact lenses (CLs) is evaluated using a new method of sustained reading performance, based on eye fixation analysis.
Methods :
Visual performance of thirty presbyopic volunteers (age: 50±5 yrs) was assessed monocularly and binocularly using monthly disposable CLs (Air Optix Plus Hydraglyde, Alcon Laboratories) with: (a) single vision (SV) lenses – uncorrected for near (b) aspheric multifocal (MF) CLs. LogMAR acuity was measured with ETDRS charts. Reading performance was evaluated using standard IReST paragraphs displayed on a screen (0.4 logMAR print size at 40cm distance). Eye movements were monitored with an infrared eyetracker (Eye-Link II, SR Research Ltd). Data analysis included computation of reading speed, fixation duration, fixations per word and percentage of regressions. Frequency distributions of fixations durations were analysed with an ex-Gaussian fitting, a convolution of a normal (with μ as the mean) and exponential (with τ as the mean) distribution, that can characterize its location and shape.
Results :
Average reading speed was 250±68 and 235±70 wpm, binocularly and monocularly, with SV CLs, improving statistically significantly to 280±67 and 260±59 wpm, respectively, with MF CLs (p<0.001 in both conditions).Moreover, fixation duration, fixations per word and ex-Gaussian parameter of fixation duration, μ, showed a statistically significant improvement when reading with MF CLs, with fixation duration exhibiting the stronger correlation (r=0.79) with improvement in reading speed. The correlation between improvement in VA and reading speed was low (r=-0.36), as was also the case between VA and any eye fixation parameter.
Conclusions :
Reading speed in a presbyopic population was found improved with MF compared to SV CL correction and was faster with binocular compared to monocular viewing: this was mainly due to the faster average fixation duration. The enhancement in reading performance could not be predicted by the observed improvement in VA. Evaluating reading performance using eye fixation analysis could offer a reliable outcome of functional vision in presbyopia correction.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.