Standards for Reporting the Optical Aberrations of Eyes

Peripheral image quality influences several aspects of human vision. Apart from off‐axis visual functions, the manipulation of peripheral optical errors is widely used in myopia control interventions. This, together with recent technological advancements enabling the measurement of peripheral errors, has inspired many studies concerning off‐axis optical aberrations. However, direct comparison between these studies is often not straightforward. To enable between‐study comparisons and to summarise the current state of knowledge, this review presents population data analysed using a consistent approach from 16 studies on peripheral ocular optical quality (in total over 2,400 eyes). The presented data include refractive errors and higher order monochromatic aberrations expressed as Zernike co‐efficients (reported in a subset of the studies) over the horizontal visual field. Additionally, modulation transfer functions, describing the monochromatic image quality, are calculated using individual wavefront data from three studies. The analysed data show that optical errors increase with increasing eccentricity as expected from theoretical modelling. Compared to emmetropes, myopes tend to have more hypermetropic relative peripheral refraction over the horizontal field and worse image quality in the near‐periphery of the nasal visual field. The modulation transfer functions depend considerably on pupil shape (for angles larger than 30°) and to some extent, the number of Zernike terms included. Moreover, modulation transfer functions calculated from the average Zernike co‐efficients of a cohort are artificially inflated compared to the average of individual modulation transfer functions from the same cohort. The data collated in this review are important for the design of ocular corrections and the development and assessment of optical eye models.

Section: Peripheral Ocular Aberrations Datamentioning

confidence: 99%

“…Despite the importance of peripheral aberrations, direct access to population data on retinal image quality is limited and the comparison between different studies is often not straightforward. Even though there are guidelines for reporting ocular aberrations, [35][36][37]…”

mentioning

confidence: 99%

Peripheral refraction and higher order aberrations

Romashchenko

Rosén²,

Lundström

2020

“…The wavefront aberration coefficients were determined up to the fourth order and are expressed in standard ophthalmic notation. 16…”

Section: Higher-order Aberrationsmentioning

confidence: 99%

Contralateral comparison of wavefront‐guided LASIK surgery with iris recognition versus without iris recognition using the MEL80 Excimer laser system

Yang

Dougherty

2009

Purpose:To compare outcomes in wavefront-guided LASIK performed with iris recognition software versus without iris recognition software in different eyes of the same patient. Methods: A randomised, prospective study of 104 myopic eyes of 52 patients undergoing LASIK surgery with the MEL80 excimer laser system was performed. Iris recognition software was used in one eye of each patient (study group) and not used in the other eye (control group). Higher order aberrations (HOAs), contrast sensitivity, uncorrected vision (UCV), visual acuity (VA) and corneal topography were measured and recorded pre-operatively and at one month and three months post-operatively for each eye. Results: The mean post-operative sphere and cylinder between groups was similar, however the post-operative angles of error (AE) by refraction were significantly smaller in the study group compared to the control group both in arithmetic and absolute means (p = 0.03, p = 0.01). The mean logMAR UCV was significantly better in the study group than in the control group at one month (p = 0.01). The mean logMAR VA was significantly better in the study group than in control group at both one and three months (p = 0.01, p = 0.03). In addition, mean trefoil, total third-order aberration, total fourth-order aberration and the total scotopic root-mean-square (RMS) HOAs were significantly less in the study group than those in the control group at the third (p = 0.01, p = 0.05, p = 0.04, p = 0.02). By three months, the contrast sensitivity had recovered in both groups but the study group performed better at 2.6, 4.2 and 6.6 cpd (cycles per degree) than the control group (p = 0.01, p < 0.01, p = 0.01). Conclusions: LASIK performed with iris recognition results in better VA, lower mean higher-order aberrations, lower refractive post-operative angles of error and better contrast sensitivity at three months post-operatively than LASIK performed without iris recognition.

“…Ocular aberrations can be quantified in terms of the coefficients of Zernike polynomials. 32 When viewed in isolation, the Zernike defocus term acts as an even-error cue to accommodation, that is, it presents information on the magnitude of the defocus but does not provide directional information relating to the sign of the error. Wilson, Decker and Roorda 23 conducted a psychophysical investigation of the role of higher-order ocular aberrations in the derivation of a directional cue to defocus.…”

mentioning

confidence: 99%

Role of ocular aberrations in dynamic accommodation control

Chin

Hampson

Mallen

2009

Background: Accommodation control is mediated by a number of cues, including blur, chromatic aberration and target proximity. Data from wavefront measurements have shown clear shifts in ocular aberrations during increasing accommodative demand, most notably a negative shift in spherical aberration. Work in adaptive optics, where aberrations have been corrected, has suggested a role for aberrations in the control of accommodation for some individuals. This study aimed to determine the relative effects of aberration correction and inversion on closed-loop stepwise accommodation responses to small increases and decreases in stimulus vergence. Methods: An adaptive optics system was used to modify ocular aberrations, while five participants viewed a high contrast target stepping 0.5 D in an inward or outward direction. Aberrations were variously unchanged, corrected or inverted following the step change in stimulus vergence. A Shack-Hartmann wavefront sensor was used to record accommodative responses to the stepwise changes in stimulus vergence. Accommodative response data were analysed using a curve fitting method to calculate the gain, latency and response time. Results: Correction of aberrations failed to have a significant effect on dynamic accommodative responses. Inversion of even-order aberration terms produced a significant reduction in accommodative response gain for outward steps in stimulus vergence. Additionally, an increase in the number of accommodative responses in the wrong direction was seen following aberration inversion. Inward steps were not altered significantly by aberration inversion. Conclusion: Accommodation in humans appears to derive a cue from the even-order aberrations of the eye to help guide the initial direction of responses to reductions in stimulus vergence (that is, disaccommodation). With all aberrations and even-order aberrations inverted, the number of incorrect directional responses to outward moving stimuli increases, suggesting that aberrations are important in determining the initial path of stepwise accommodative responses.