Influence of centre near design multifocal CLs on visual acuity in young myopes and presbyopes

Authors : Shrilekha Vedhakrishnan(1); Maria Vinas(1); Pilar Casado Moreno (1); Clara Benedi-Garcia (1); Carlos Dorronsoro (1); Susana Marcos (1)

(1) Instituto de Optica, Madrid, Madrid, Spain

Date: June 2020

Source: ARVO 2020 Abstracts - video presentation

Influence of centre near (CN) design multifocal lenses (1-day Acuvue Moist) on visual acuity was measured in young adults and presbyopes under cyclopegic and natural conditions with the effect of different pupil sizes modelled using an adaptive optics system. Overall the lenses performed similarly at improving near VA between cyclopleged young adults and presbyopes when compared to no lenses, and created no apparent difference to near VA in accommodating young adults, however there was slight degradation to distance VA.

Centre near design multifocal lenses, when fit to young adults in add powers up to +2.50 do not appear to reduce visual acuity at near, however there appeared slight degradation to VA at distance when compared to the without multifocal lenses condition.

• Meeting abstract so not fully peer-reviewed
• Statistics are not included in the abstract and no error bars are displayed on the presented charts to hep infer significance of findings - consequently outcomes can only be considered as observational
• Young adults examined so can only infer if the same outcomes would be found in children
• Outcomes from centre distance designs would be interesting to know for comparison

The lead author explained in her video presentation that centre distance design multifocal CLs are proposed to slow MP by inducing peripheral defocus, while centre near designs instead compensate for accommodation lag as a result of inducing negative spherical aberration.

In this study, centre near (CN) design (1-day Acuvue moist: BVP -2.00D with adds: +1.25,+1.75,+2.50) were investigated using an adaptive optics system in two groups of participants with and without cycloplegia (degree of cycloplegia not disclosed).

Groups:

• Young myopes (n=10) 26.9 ± 2.2yrs; -4.50D
• Presbyopes (n=5) 53 ± 2yrs; -2.75D

Main investigation:

• Compared visual degradation or benefit at far compared to near with MCL's in both groups
• Constancy in the visual through focus performance between young myopes and presbyopes
• Role of accommodation in the visual performance with the CN multifocal CL's

Sessions:

1. Paralysed accommodation; pupil sizes 3, 4, 5mm
2. Natural accommodation and pupil size

Measures:

• Through focus VA, tumbling E, alternative forced choice
  Adaptive optics:
• Badal system to induce and correct defocus
• Charts displayed on CRT monitor
• Pupil size controlled using an artificial pupil

Conclusions
All three multifocal adds improve VA at near in presbyopes and in cyclopleged young adults as expected, however the results revealed an apparent slight decrease to distance VA across all subjects when compared to without multifocal lenses. The +1.25D add lens showed similar behaviour to the no lens condition, with depth of focus increasing for the +1.75D and +2.25D adds with increasing pupil sizes. The main outcome of interest when considering centre near multifocal designs for myopia control in children is that VA is maintained across all distances with active accommodation. However, there was considerable inter subject variation in responses described by the authors as likely being due to differences in interaction between unique individual optical aberrations profiles and the optical aberration profiles provided by the lenses.

Title: Vision with multifocal contact lens in myopes and presbyopes.

Purpose: Multifocal contact lenses (MCLs), working under the principle of simultaneous vision are known solutions for Presbyopes, but they are also proposed to control the progression of Myopia. We evaluated visual performance with Center-Near design MCLs in Presbyopes and Myopes for different distances, viewing conditions and pupil diameters.

Methods: Measurements were performed in a group of 10 myopic subjects (MS, age: 24-27; SE: ±to-4.5D) and 5 presbyopes (PS, age: 47-58; SE:-2.75-+2.5D) on an Adaptive Optics system. All subjects were fitted with MCLs (three adds: LA: +1.25D; MA: +1.75D; HA: +2.5D), all with the same distance power (-2D). Residual defocus was corrected by a Badal System (BS). Decimal Visual Acuity (VA) was measured using an 8- Alternative Forced Choice procedure, tumbling E letter displayed on a CRT monitor (Visage, Cambridge research system), at different vergences (Far: 0D, Intermediate: +1.75D, Near: +2.50D). Measurements were performed both for paralyzed accommodation (PA, 5, 4 & 3 mm pupil), and natural accommodation (NA, natural pupil). Eye without the lens (NL) was measured as a control. The DOF was estimated as the dioptric range for which VA is 0.5 or better. The effect of the lens, addition, pupil diameter and accommodation was analyzed in the 2 study populations.

Results: Under NA, VA with MCLs ranged from 1.13-1.07 (MS) and 0.95-0.8 (PS) for far, and 1.13-1.07 (MS) and 0.5-0.45 (PS) for near, decreasing by a factor of 1.18/1.09 (MS/PS) for the LA, 1.24/1.29 (MS/PS) for the MA and 1.22/1.21 (MS/PS) for the HA at far. Under PA, average VA values are 1.32 times lower than the NA values in MS and 1.05 times in PS for 5mm Pupil. The average RMS difference between the TFVA curves under NA and PA (7/5mm pupils) was 0.23/0.04 (MS/PS, NL), 0.21/0.03 (MS/PS, LA), 0.17/0.06 (MS/PS, MA), 0.13/0.03 (MS/PS, HA). DOF ranged from -3D/-2.5D (NL) to 1D/1D (HA) in YS (NA/PA) and from -2D/-1.5D (NL) to 1D/1D (HA) in PS (NA/PA).

Conclusions: MCLs decrease VA at far, both in young subjects and presbyopes, while increasing DOF(under paralyzed accommodation in both groups, and natural conditions in presbyopes). Both effects are proportional to the magnitude of the lens addition. In accommodating young subjects, MCLs do not seem to compromise on near acuity and they are maintained as the NoLens state.

Abstract link is here