Abstract
Purpose :
With increasing use of low-addition progressive lenses in relieving the symptoms of eye strain, one of the pertinent questions is how would these lenses affect the amplitude of accommodation (AA) and near point of convergence (NPC) and other binocular vision tests of the wearers. The objective of our study was to investigate the one-month effect of wearing low-addition progressive lenses on binocular vision of a group of Chinese young adults.
Methods :
A total of 120 healthy Chinese adults with a mean age of 29 ± 5.4 years (range from 22 to 44 years old) were recruited. The participants were divided into two groups: 60 wearing the low-addition progressive lenses with blue cut coating (Essilor EyezenTM) and 60 wearing normal anti-reflective coated single vision lenses. Binocular vision (BV) tests such as AA and NPC were measured using the push up techniques with the RAF rulers. The other BV parameters measured were distance and near phoria, AC/A ratio, negative relative accommodation (NRA), positive relative accommodation (PRA), negative (NFV) and positive fusional vergences (PFV) for distance and near (D&N), vergence facility (VF, using 3BI/12BO), and accommodative facility (AF) tests (and ±1.00 D and ±1.50D flippers according to age). All the BV tests were performed before and one month after wearing the lenses. Results were analyzed using t-test to compare the BV readings between baseline and 1 month follow up in the two groups of participants.
Results :
There were no significant differences in almost all the optometric tests, including AA and NPC. AA at baseline (11.5 ± 5.3 D) was found to be no different from AA (11.4 ± 4.9 D) after 1 month wearing the low-addition progressive lenses (p = 0.19). Similarly, the change in NPC, between baseline (6.3 ± 2.3 cm) and measurement 1 month later (6.9 ± 2.3 cm) was statistically insignificant (p = 0.65). However, the recovery value of PFV had shown significant increase from 14.3 ± 7 PD at baseline to 16.6 ± 8 PD one month after wearing low-addition progressive lenses (P=0.02). There were significant improvement in VF and AF (monocularly and binocularly). But, these improvements were also observed in single vision lens wearers.
Conclusions :
Wearing low-addition progressive lenses for one month does not affect the AA and NPC and most of the binocular vision tests of the wearers in general.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.