Slope-based eccentric photorefraction: theoretical analysis of different light source configurations and effects of ocular aberrations

Roorda, Austin; Campbell, Melanie C. W.; Bobier, William R.

doi:10.1364/josaa.14.002547

Cited by 49 publications

(54 citation statements)

References 17 publications

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“…Detailed descriptions of the technique can be found elsewhere (Roorda, Campbell, & Bobier, 1997; Schaeffel et al, 1993) and only a brief description will be provided here. The subject was aligned at 1.0 m from a set of LED light sources immediately beneath the PR camera aperture.…”

Section: Methodsmentioning

confidence: 99%

Accommodative and vergence responses to conflicting blur and disparity stimuli during development

Candy

2009

Journal of Vision

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Accommodative and vergence responses of the typically developing visual system are generated using a combination of cues, including retinal blur and disparity. The developmental importance of blur and disparity cues in generating these motor responses was assessed by placing the two cues in conflict with each other. Cue-conflicts were induced by placing either −2 D lenses or 2 MA base-out prisms before both eyes of 140 subjects (2.0 months to 40.8 years) while they watched a cartoon movie binocularly at 80 cm. The frequency and amplitude of accommodation to lenses and vergence to prisms increased with age (both p < 0.001), with the vergence response (mean ± 1 SEM = 1.38 ± 0.05 MA) being slightly larger than the accommodative response (1.18 ± 0.04 D) at all ages (p = 0.007). The amplitude of these responses decreased with an increase in conflict stimuli (1 to 3 D or MA) (both p < 0.01). The coupled vergence response to −2 D lenses (0.31 ± 0.06 MA) and coupled accommodative response to 2 MA base-out prisms (0.21 ± 0.02 D) were significantly smaller than (both p < 0.001) and poorly correlated with the open-loop vergence (r = 0.12; p = 0.44) and open-loop accommodation (r = −0.08; p = 0.69), respectively. The typically developing visual system compensates for transiently induced conflicts between blur and disparity stimuli, without exhibiting a strong preference for either cue. The accuracy of this compensation decreases with an increase in amplitude of cue-conflict.

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Section: Methodsmentioning

confidence: 99%

Accommodative and vergence responses to conflicting blur and disparity stimuli during development

Candy

2009

Journal of Vision

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“…With this technique, the refractive state of non-cooperative subjects can be determined from a distance. The details of this method are described elsewhere (Schaeffel et al, 1987;Roorda et al, 1997;Malkki and Kröger, 2005). In our setup (Fig.…”

Section: Optical Properties Of the Eyementioning

confidence: 99%

“…The nature of an optical system can, to some degree, be analyzed from the reflexes captured with eccentric slope-based IR videorefractometry, although detailed interpretations should be carried out with caution (Roorda et al, 1997). In all birds with multifocal systems, except for most of the parrots (Psittaciformes) there were only two refractive zones, with the outer one having less refractive power.…”

Section: Structure Of the Optical Systemmentioning

confidence: 99%

Multifocal optical systems and pupil dynamics in birds

Lind

Kelber

Kröger

2008

Journal of Experimental Biology

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SUMMARYIn animal eyes of the camera type longitudinal chromatic aberration causes defocus that is particularly severe in species with short depth of focus. In a variety of vertebrates, multifocal optical systems compensate for longitudinal chromatic aberration by concentric zones of different refractive powers. Since a constricting circular pupil blocks peripheral zones, eyes with multifocal optical systems often have slit pupils that allow light to pass through all zones, irrespective of the state of pupil constriction. Birds have circular pupils and were therefore assumed to have monofocal optical systems. We examined the eyes of 45 species (12 orders) of bird using videorefractometry, and the results are surprising: 29 species (10 orders) have multifocal systems, and only five species (five orders) have monofocal systems. The results from 11 species (four orders) are inconclusive. We propose that pupils ʻswitchingʼ between being fully opened (multifocal principle) to maximally closed (pinhole principle) can make multifocal optical systems useful for animals with circular pupils. Previous results indicate that mice have both multifocal optical systems and switching pupils. Our results suggest that parrots may use a similar mechanism. By contrast, owl pupils responded weakly to changes in illumination and stayed remarkably wide even in full daylight. Moreover, the parrots opened their pupils at higher light levels than owls, which correlates with the differences in sensitivity between diurnal and nocturnal eyes.

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“…Higher-order monochromatic aberrations, which may disrupt the light distribution in the pupil. 15,16 In a system with an extended light source, the slope of the light distribution in the pupil plane can be fit with a linear regression to estimate refractive error over a relatively wide operating range. 7,16,17 The conversion of the slope of the linear regression into a refraction estimate has to be based on an empiric calibration rather than the theoretical analysis discussed previously, however, because of the additional factors.…”

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confidence: 99%