Do myopia controlling spectacles with lenslets affect visual quality?

Title: Short-term visual performance through myopia control spectacle lenses with lenslets

Authors: Xue Li (1,2,3), Chenglu Ding (1,2), Yuhao Li (1,2), Ee Woon Lim (3,4), Yi Gao (3,4), Bruno Fermigier (5), Adeline Yang (3,4), Hao Chen (1,2,3), Jinhua Bao (1,2,3)

1: Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang Province, China
2: National Clinical Research Centre for Ocular Diseases, Wenzhou, Zhejing Province, China
3: Wenzhou Medical University-Essilor International Research Centre (WEIRC), Wenzhou, Zhejiang Province, China
4: R&D AMERA, Essilor International, Singapore, Singapore; 5R&D Essilor International, Creteil, France

Reference: ARVO 2021 abstract

The newest designs of spectacle lenses for myopia control feature a clear central area and a surrounding 'treatment zone' of defocus lenslets. Given that wearers will often look through the 'treatment zone' in off-axis directions of gaze and if their frames move position, it is important to understand the visual quality. This study compared visual acuity and contrast sensitivity function of children wearing honeycomb-configuration design (termed 'HC', eg. DIMS) or concentric ring slightly aspherical lenslet (SAL) and highly aspherical lenslet (HAL) spectacle lenses designs for myopia control. All three were compared to single vision spectacles.

Visual acuity through the three 'treatment zone' designs was 3-5 letters reduced compared to single vision lenses, with HL showing 1-2 letters more reduction than HAL or SAL. Contrast sensitivity was unaffected for low spatial frequencies. Mid spatial frequencies were affected by HAL and HC but not SAL, and high spatial frequencies were affected by HC more than SAL and HAL.

What does this mean for your clinical practice? Practitioners can advise children that they may notice alteration to their vision through the 'treatment zone' of their myopia control lenses, but the impact should be minimal and the HAL/SAL clinical trial has shown adaptation is typically swift. There's more to learn about how these differences between lens designs translate into clinical practice or even patient preferences. 

Purpose:  To evaluate the impact on central distance visual acuity (VA) and contrast sensitivity (CS) in children of three different spectacle lens designs with lenslets used for myopia control while looking through the peripheral zones containing the lenslets.

Methods:  Distance VA and CS were measured using Freiburg Visual Acuity and Contrast test (FrACT) and CSV-1000 (Vector Vision Carp, USA), respectively.  For each test, four spectacle lens designs were evaluated in random order: standard single vision (SVL) as a control, spectacle lens with concentric rings of highly aspherical lenslets (HAL), spectacle lens with concentric rings of slightly aspherical lenslets (SAL) and spectacle lens with honeycomb configuration of spherical lenslets (HC).  To ensure vision through the lenslets zones, zones without lenslets were patched.  50 myopic children (mean age 12.7 ± 1.7 years, range 10 to 15 years, mean spherical equivalent refraction (SER) 3.22 ± 1.57D, range -6.50 to -0.38D) participated in the VA test; 36 myopic children (mean age 13.2 ± 1.2 years, range 10 to 16 years, mean SER 3.20 ± 1.67D, range -7.25 to -0.75D) participated in the CS test.  All tests were done monocularly on the right eye with corrected-to-normal vision.

Results: Compared to SVL, VA through the lenslet zones of HAL, SAL and HC decreased significantly by 0.07 ± 0.09, 0.06 ± 0.09, 0.09 ± 0.07 LogMAR, respectively (all p<0.01).  Decrease in VA was similar in HAL and SAL (p>0.9) while significantly larger in HC compared to HAL (p=0.02) and to SAL (p=0.03).  VA changes induced by lenslets showed no significant correlation with SER (all p> 0.05), but had a weak positive association with age for SAL (r=0.36, p=0.01) and HC (r=0.31, p=0.03) but not for HAL (p=0.3).  The lenslet structures did not affect CS at low spatial frequency (3 cycles per degree (cpd), p=0.8).  At mid to high spatial frequencies (6 to 18 cpd), CS was significantly reduced by HAL and HL (all p<0.05), but not SAL (p>0.05) compared to SVL.  At high spatial frequencies (12 to 18 cpd) both SAL and HAL reduced CS significantly less than HC (all p<0.01).

Conclusions: When looking though the lenslet structures, short-term visual performance was minimally reduced by spectacle lenses with lenslets compared to SVL.  Concentric rings of aspherical lenslets had significantly lower impact on both VA and CS then honeycomb configuration of spherical lenslets.

Disclosures:  XUE LI, None; Chenglu Ding, None; yuhao li, None; Yi Gao, R&D AMERA, Essilor International (Code E (Employment)); Adeline Yang, R&D AMERA, Essilor International (Code E (Employment)); Hao Chen, None; Jinhua Bao, None