Optical plasticity in fish lenses

Kröger, Ronald H. H.

doi:10.1016/j.preteyeres.2012.12.001

Cited by 20 publications

(19 citation statements)

References 84 publications

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“…However, the presence of a gradient index profile in the lens would in fact be consistent with this finding. A compensatory role of the gradient in crystalline lens has been reported in fish [34], porcine lenses [35] and young lenses [36,37]. Further estimates of the crystalline lens GRIN profile will be enabled by inverse modeling from OCT data of the lens collected in two orientations (anterior lens up and posterior lens up) ex vivo.…”

Section: Discussionmentioning

confidence: 96%

Three-dimensional OCT based guinea pig eye model: relating morphology and optics

Pérez-Merino¹,

Velasco-Ocaña²,

Martinez-Enriquez³

et al. 2017

Biomed. Opt. Express

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Custom Spectral Optical Coherence Tomography (SOCT) provided with automatic quantification and distortion correction algorithms was used to measure the 3-D morphology in guinea pig eyes (n = 8, 30 days; n = 5, 40 days). Animals were measured awake in vivo under cyclopegia. Measurements showed low intraocular variability (<4% in corneal and anterior lens radii and <8% in the posterior lens radii, <1% interocular distances). The repeatability of the surface elevation was less than 2 µm. Surface astigmatism was the individual dominant term in all surfaces. Higher-order RMS surface elevation was largest in the posterior lens. Individual surface elevation Zernike terms correlated significantly across corneal and anterior lens surfaces. Higher-orderaberrations (except spherical aberration) were comparable with those predicted by OCTbased eye models.

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Section: Discussionmentioning

confidence: 96%

Three-dimensional OCT based guinea pig eye model: relating morphology and optics

Pérez-Merino¹,

Velasco-Ocaña²,

Martinez-Enriquez³

et al. 2017

Biomed. Opt. Express

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“…Fish lenses are typically spherical. Since the cornea provides little focusing power in an aquatic environment, fish obtain high focusing power with spherical lenses having a high index of refraction (Kroger, 2013;Sivak, 2004). However, rays of light passing through the periphery and center of a spherical lens focus at different distances, resulting in spherical aberration.…”

Section: The Eye and Ocular Mediamentioning

confidence: 99%

Proximate and ultimate causes of variable visual sensitivities: Insights from cichlid fish radiations

Carleton

Dalton

Escobar‐Camacho

et al. 2016

Genesis

127

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Animals vary in their sensitivities to different wavelengths of light. Sensitivity differences can have fitness implications in terms of animals’ ability to forage, find mates and avoid predators. As a result, visual systems are likely selected to operate in particular lighting environments and for specific visual tasks. This review focuses on cichlid vision, as cichlids have diverse visual sensitivities, and considerable progress has been made in determining the genetic basis for this variation. We describe both the proximate and ultimate mechanisms shaping cichlid visual diversity using the structure of Tinbergen’s four questions. We describe 1) the molecular mechanisms that tune visual sensitivities including changes in opsin sequence and expression; 2) the evolutionary history of visual sensitivity across the African cichlid flocks; 3) the ontological changes in visual sensitivity and how modifying this developmental program alters sensitivities among species; and 4) the fitness benefits of spectral tuning mechanisms with respect to survival and mating success. We further discuss progress to unravel the gene regulatory networks controlling opsin expression and suggest that a simple genetic architecture contributes to the lability of opsin gene expression. Finally, we identify unanswered questions including whether visual sensitivities are experiencing selection, and whether similar spectral tuning mechanisms shape visual sensitivities of other fishes.

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“…However, the changes in anterior corneal curvature were not significantly associated with the changes in ocular spherical refraction (p40.05), which suggests that diurnal fluctuations in the other optical components of the eye, such as curvature of the crystalline lens or posterior cornea (or variations in the corneal or crystalline lens refractive index), could also be involved in the changes observed in the overall ocular refraction. Diurnal fluctuations in the gradient refractive index of the crystalline lens have been observed in other species, [66][67][68] and have been shown to be related to variations in retinal dopamine levels; however, diurnal changes in the refractive index of the human crystalline lens have not previously been examined. A limitation of the measurements in our current study is that the spherical refraction data was analyzed over a 5-mm pupil, but the anterior corneal keratometry values reflect only the central 2-3 mm of corneal curvature, which may have influenced the strength of the correlation observed between these variables.…”

Section: Discussionmentioning

confidence: 99%