Monofocal Extended Range Of Vision: Escrs Funded Study.

It is recognised that some patients after emmetropic monofocal intraocular lens (IOL) cataract surgery have good reading ability. The aim the study was to screen the patients with monofocal IOL to find out the incidence of patients not needing glasses to see 20/40 and 0.2 LogMAR (J4) for distance and near., to analyse these eyes in comparison to other eyes screened to find factors responsible for 20/40 and J4 unaided vision and to predict a formula of probability of pseudoaccommodation.

University Hospitals Sussex NHS Foundation Trust, Brighton. UK

This was a prospective, single eye study funded by ESCRS (Clinicaltrials.gov:NCT04011696). Patients expected ≤20/40 unaided vision were recruited. At 3-9 months, refraction, uncorrected & best-corrected distance & uncorrected near LogMAR acuity, spherical equivalent (SEQ), pupil size, spherical (Z40), vertical coma (Z3-1) aberration, reading speed and smallest print size were assessed. Refractive astigmatism was classified as against-the-rule (ATR), with-the-rule (WTR), oblique (OB) and no-astigmatism (NA). Data on preoperative axial length (preopAL) and anterior chamber depth (preopACD) were collected. Patients with good distance and near vision were classed as ‘cases’.

Data on 301 were available (2 died,109 withdrew in pandemic). 29 patients (9.6%, 95% CI: 6.5-13.5) were cases. Univariate analysis revealed preopACD, SEQ, total spherical aberration and mesopic pupil size to be significant. Wherease, multivariate logistic regression modelling identified: preopAL, SEQ, total eye spherical aberration and mesopic pupil size to be significant. Probability of achieving good distance and near vision without glasses: Logit (P) = 12.54 - (0.484 X preopAL) – (0.884 X mesopic pupil size) – (13.1 X total spherical aberration) – (0.714 X SEQ). Where logit(p) = natural log (P/1-P) and P is the probability of having pseudoaccommodation. The pseudo R² for this model was 0.16 (IQR: 0.11 - 0.23).

A combination of low myopic spherical equivalent, lower total eye spherical aberration, shorter preoperative axial length and smaller pupil size increases the chances of achieving pseudoaccommodation. The best probability of achieving pseudoaccommodation ranged between 11% to 23% in our study suggesting that other cognitive and neurological factors which were not studied by us in this study may have a significant role in aiding pseudoaccommodation.