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Visual interaction of 2nd to 5th order Zernike aberration terms with vertical coma
Author(s) -
Hu Chuan,
Ravikumar Ayeswarya,
Hastings Gareth D,
Marsack Jason D
Publication year - 2020
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1111/opo.12718
Subject(s) - zernike polynomials , strehl ratio , coma (optics) , spherical aberration , contrast (vision) , optics , keratoconus , piston (optics) , visual acuity , aberrations of the eye , mathematics , residual , ophthalmology , computer science , physics , artificial intelligence , optometry , lens (geology) , adaptive optics , wavefront , medicine , algorithm , cornea
Purpose In order to better understand the optical consequence of residual aberrations during conventional rigid contact lens wear in keratoconus, this study aimed to quantify the visual interaction between positive vertical coma (C(3, −1)) and other individual 2 nd to 5 th radial order Zernike aberration terms. Methods The experiment proceeded in two parts. First, two levels of C(3, −1) ( target term) were simulated. Individual Zernike aberration terms from the 2 nd to 5 th radial orders ( test terms) were combined in 0.05‐µm steps a) from −2.00 µm to +2.00 µm with +1.00 µm of C(3, −1) and b) from −1.00 µm to +1.00 µm with +0.50 µm of C(3, −1). The resulting combinations were used to calculate the logarithm of the visual Strehl ratio (logVSX) and predict the relative beneficial or deleterious impact of the interaction. Second, for test terms where an interaction was predicted to provide more than a 0.25 logVSX benefit compared to C(3, −1) alone, high contrast logMAR acuity charts were constructed (simulating the manner in which the test + target term combinations would impact the retinal image of the chart), and randomly read by three well‐corrected, typically‐sighted individuals through a 3.0‐mm diameter artificial pupil. Results When combined with positive C(3, −1), C(3, −3), C(4, −4), C(5, −5), C(5, −3), and C(5, −1) exhibited better visual image quality compared with C(3, −1) alone. Ratios of the test terms to target term providing maximal benefit remained constant for both +0.50 µm and +1.00 µm of C(3, −1). C(3, −3) and C(5, −1) had the largest predicted beneficial effect, with the maximal effect for +1.00 µm of C(3, −1) occurring with +0.35 µm of C(5, −1) and −1.00 µm of C(3, −3). When individuals read letter charts convolved with the point spread function derived from C(3, −1) combined with C(3, −3) and C(3, −1) combined with C(5, −1), the maximal beneficial effect was 0.27 logMAR (13.5 letters) for C(3, −3) and 0.36 logMAR (18 letters) for C(5, −1). Conclusions While most interactions reduced visual image quality, combinations of C(3, −3) (vertical trefoil) and C(5, −1) (vertical secondary coma) provided a clinically relevant beneficial effect in the presence of C(3, −1) (vertical coma) which was demonstrated in both through‐focus simulation and chart reading tests. Future work will examine whether these effects persist in the presence of the entire spectrum of residual aberrations seen in the eyes of individuals with keratoconus.