Effect of fogging lenses on accommodation using an open-view portable wavefront autorefractor

To investigate the effect of a + 2.00 D fogging lens on accommodative behavior during measurements with an open-view handheld wavefront autorefractor, considering refractive status and fogging duration.

Participants underwent six consecutive 10-second measurements per eye using an open-view autorefractor: three without and three with a fogging lens. Subjects were classified as myopic, emmetropic or hyperopic based on the mean spherical refraction of the right eye. Bland-Altman analysis assessed device repeatability and the effect of fogging (with vs without), both overall and by refractive group. The influence of acquisition time was evaluated by comparing the first 5 s with the full 10-second recordings.

Sixty-one young adults (25.02 ± 6.16 years; spherical refraction -0.80 ± 2.21 D) were included: 34.4% myopes, 42.6% emmetropes and 22.9% hyperopes. Ten-second measurements showed excellent repeatability, with mean differences near zero and 95% limits of agreement within ±0.50 D, regardless of fogging. Shortening acquisition to 5 s maintained negligible bias but increased variability by ∼20%. The fogging lens induced heterogeneous responses across refractive groups. In myopic and emmetropic eyes, most showed no change (52% and 58%), and accommodative relaxation occurred infrequently (10% and 17%). In contrast, 43% of hyperopic eyes showed accommodative relaxation, with a mean refractive shift of 0.84 D, suggesting a clinically meaningful response.

The effect of a + 2.00 D fogging lens depends on refractive status. Routine use may provide limited additional benefits in myopic and emmetropic subjects, whereas hyperopic individuals appear more likely to benefit from its selective use.