Abstract
Purpose :
Corneal aberrometry is a valuable tool for evaluating the optical quality of the cornea in eyes with various pathologies, and it has been widely applied in clinical practice. Recently, it became possible to measure wavefront aberrations of the total cornea with directly measuring the posterior corneal surface as well as the anterior corneal surface. However, the normal range has not been determined based on large population data. In this study, we tried to determine normal range of corneal higher-order aberrations.
Methods :
We examined 844 eyes of 422 subjects without corneal diseases. The subjects’ age was 47.6 ± 22.1 (mean ± standard deviation) years. All eyes were measured by anterior segment optical coherence tomography (OCT) (CASIA SS1000, Tomey Co., Japan), and higher-order aberrations of the total cornea for 4- and 6-mm pupils were calculated based on the height data. The normal range of corneal higher-order aberrations was defined as the mean ± 2×standard deviation. In addition, 49 eyes with keratoconus were examined, and the proportion of eyes that were included in the normal range was calculated.
Results :
The normal ranges of corneal higher-order aberrations were 0.046-0.338 µm (4mm) and 0.121-0.740 µm (6mm) for coma-like aberration (S3+5), 0.055-0.338 µm (4mm) and 0.136-0.577 µm (6mm) for spherical-like aberrations (S4+6), and 0.110-0.450 µm (4mm) and 0.255-0.883 µm (6mm) for total higher-order aberrations (S3+4+5+6). When these normal ranges were applied to eyes with keratoconus, the proportion of eyes within the normal range was 0 % (both 4 and 6 mm) for coma-like aberration, 16 % (4mm) and 12 % (6 mm) for spherical-like aberration, and 0 % (both 4 and 6 mm) for total higher-order aberrations.
Conclusions :
We proposed the normal range of corneal higher-order aberrations which were evaluated by anterior segment OCT. Because the obtained values of coma-like and total higher-order aberrations were beyond the normal ranges in all keratoconic eyes examined in this study, the present normal ranges appeared to be clinically useful.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.