Immediate effect of a tear enhancer and meibomian gland expression on the corneal surface and whole eye higher order aberrations

Abstract

Purpose: To investigate changes in higher order ocular aberrations (HOA) induced by the administration of 0.15% sodium hyaluronate tear enhancer (TE) and meibomian gland expression (ME) on the tear film of normal subjects. Methods: HOA values were obtained from the corneal surface (CS) and whole eye (WE), using a corneal topographer and Shack–Hartmann aberrometer, from both eyes of 50 subjects (25 females, mean age ± sd 32.5 ± 11.0 years, and 25 males, 33.88 ± 11.2 years) for two pupil sizes (3 and 6 mm) in a dark environment. One drop of Blink Contacts™ (Abbott Medical Optics) was instilled into the right eye and HOA measurements repeated after 30 s. After 1 h, the meibomian glands of the left lower eyelid were gently squeezed and HOA measurements repeated after 30 s. Results: There was no significant difference for CS and WE root mean square (RMS) HOAs between right and left eyes before (both pupil sizes) and after TE use or ME (3 mm pupil). For 6 mm pupil, TE use significantly reduced the WE RMS HOA (p < 0.05, mean ± sd) for Z40 (0.297 ± 0.136 to 0.053 ± 0.069), and Z55 (0.221 ± 0.372 to 0.098 ± 0.121) while ME significantly increased CS RMS HOA (p < 0.05, mean ± sd) for Z3−3 (0.799 ± 1.178 to 1.302 ± 1.991) and Z44 (0.594 ± 1.184 to 0.988 ± 1.463). In general, the change in HOA was significantly correlated with the initial value before TE use or ME (p < 0.05). Conclusion: There were no detectable differences between right and left eyes. For the 6 mm pupil, the tear enhancer tended to improve optical performance of the WE and meibomian gland expression tended to reduce the optical performance at the CS.