Abstract
Purpose :
Multifocal contact lenses (MCLs) are widely adopted for presbyopia correction and have demonstrated some benefits for myopia control. However, the impact of zonal distribution and add power on visual quality remains unexplored. Employing a custom Adaptive Optics (AO) visual simulator, we systematically examined how refractive zonal MCL design parameters influence visual acuity (VA), contrast sensitivity (CS), and visual preference (VP).
Methods :
Using a Spatial Light Modulator in an AO device 8 MCLs were mapped onto the subjects’ pupils. These included: 5 symmetric Center Distance (CD) Bifocal lenses (3, 4, and 5-mm central zones, peripheral add +2.5D); 2 CD-4mm lenses (+1.5 and +5D adds); a Symmetric Center Near (CN) Bifocal lens (4-mm central zone, +2.5D add); and 2 Asymmetric Bifocal lenses (near inferior NI and near nasal NN) with +2.5D add, along with a plano control (PC). VA (tumbling E-letter), CS (qCSF, 12 spat. freq. 0.25-36 cycles/°, 2 orientations), and VP (2AFC, confidence weighted scoring of natural images, 28 pairs) were measured in 4 subjects (27.5±2.4 yrs; 0.25±0.4D spherical error). Stimuli were presented on a 2.5° minidisplay illuminated at 555nm. Best distance-corrected VA was measured for all patterns. CS (measured for the PC and lenses with the best/worst VA) was described by peak sensitivity (PS) and area under CS function (AUCSF). VP was the sum of weighted scores (±10, ±5, ±1 individual scores; VP full ± 280 scale).
Results :
VA varied across lenses. PC had the highest mean VA (-0.23±0.15logMAR). CD-5mm showed lowest VA loss (shift: 0.05±0.09logMAR, p=0.72) and highest VP (198). Conversely, CN showed highest VA loss (shift: 0.24±0.17logMAR, p=0.12) and low VP (-127.5), followed by CD-3mm (shift: 0.19±0.16logMAR, p=0.2; VP=-164). No significant differences were found in PS and AUCSF between PC and best lens (42.6±18.7 & 42.8±34.4, p=0.99 and 283.4±221.9 & 378.1±463.3, p=0.67). However, the worst pattern significantly reduced both PS (15.8±9) and AUCSF (50.9±25.1) compared to the PC (p=0.02 & 0.05).
Conclusions :
Larger CD refractive zones in MCLs showed comparable VA to the plano lens, whereas CN and smaller CD lenses led to a notable decrease in VA. CS varied across individuals and lenses. Altogether, changes in functional and perceptual outcomes predicted by AO visual simulation reveal the impact of design parameters on visual quality, and those may be customized/optimized for each patient.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.