scholarly journals Retinal factors of visual sensitivity in the human fovea

2021 ◽  
Author(s):  
Niklas Domdei ◽  
Jenny L. Reiniger ◽  
Frank G. Holz ◽  
Wolf Harmening
Keyword(s):  
Adaptive Optics ◽  
Outer Segment ◽  
Visual Sensitivity ◽  
Segment Length ◽  
Retinal Eccentricity ◽  
Small Spot ◽  
Steep Decline ◽  
Human Participants ◽  
Specialized Region ◽  
Cone Density

AbstractHumans direct their gaze towards visual objects of interest such that the retinal images of fixated objects fall onto the fovea, a small anatomically and physiologically specialized region of the retina displaying highest visual fidelity. One striking anatomical feature of the fovea is its non-uniform cellular topography, with a steep decline of cone photoreceptor density and outer segment length with increasing distance from its center. We here assessed in how far the specific cellular organization of the foveola is reflected in visual function. Increment sensitivity to small spot visual stimuli (1 x 1 arcmin, 543 nm light) was recorded psychophysically in 4 human participants at 17 locations placed concentric within a 0.2-degree diameter around the preferred retinal locus of fixation with adaptive optics scanning laser ophthalmoscopy based microstimulation. While cone density as well as maximum outer segment length differed significantly among the four tested participants, the range of observed threshold was similar, yielding an average increment threshold of 3.3 ± 0.2 log10 photons at the cornea. Thresholds were correlated with retinal eccentricity, as well as cone density and outer segment length. Biophysical simulation allowed to develop a model of foveal sensitivity based on these parameters, explaining at least 37% of the observed threshold variability. Based on high reproducibility in replicate testing, the residual variability is assumed to be caused by individual cone and bipolar cell weighting at the specific target locations.

scholarly journals The Relationship Between Perifoveal L-Cone Isolating Visual Acuity and Cone Photoreceptor Spacing—Understanding the Transition Between Healthy Aging and Early AMD

2021 ◽  
Vol 13 ◽  
Author(s):  
Rigmor C. Baraas ◽  
Åshild Horjen ◽  
Stuart J. Gilson ◽  
Hilde R. Pedersen
Keyword(s):  
Outer Segment ◽  
Healthy Aging ◽  
Segment Length ◽  
Retinal Eccentricity ◽  
Cone Photoreceptor ◽  
Cone Structure ◽  
Age Related ◽  
Risk Of Progression ◽  
The Relationship ◽  
Cone Density

Background: Age-related macular degeneration (AMD) is a multifactorial degenerative disorder that can lead to irreversible loss of visual function, with aging being the prime risk factor. However, knowledge about the transition between healthy aging and early AMD is limited. We aimed to examine the relationship between psychophysical measures of perifoveal L-cone acuity and cone photoreceptor structure in healthy aging and early AMD.Methods and Results: Thirty-nine healthy participants, 10 with early AMD and 29 healthy controls were included in the study. Multimodal high-resolution retinal images were obtained with adaptive-optics scanning-light ophthalmoscopy (AOSLO), optical-coherence tomography (OCT), and color fundus photographs. At 5 degrees retinal eccentricity, perifoveal L-cone isolating letter acuity was measured with psychophysics, cone inner segment and outer segment lengths were measured using OCT, while cone density, spacing, and mosaic regularity were measured using AOSLO. The Nyquist sampling limit of cone mosaic (Nc) was calculated for each participant. Both L-cone acuity and photoreceptor inner segment length declined with age, but there was no association between cone density nor outer segment length and age. A multiple regression showed that 56% of the variation in log L-cone acuity was accounted for by Nc when age was taken into account. Six AMD participants with low risk of progression were well within confidence limits, while two with medium-to-severe risk of progression were outliers. The observable difference in cone structure between healthy aging and early AMD was a significant shortening of cone outer segments.Conclusion: The results underscore the resilience of cone structure with age, with perifoveal functional changes preceding detectable changes in the cone photoreceptor mosaic. L-cone acuity is a sensitive measure for assessing age-related decline in this region. The transition between healthy aging of cone structures and changes in cone structures secondary to early AMD relates to outer segment shortening.

scholarly journals Three-dimensional composition of the photoreceptor cone layers in healthy eyes using adaptive-optics optical coherence tomography (AO-OCT)

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245293
Author(s):  
Adrian Reumueller ◽  
Lorenz Wassermann ◽  
Matthias Salas ◽  
Markus Schranz ◽  
Valentin Hacker ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Adaptive Optics ◽  
Outer Segment ◽  
Three Dimensional ◽  
Optical Coherence ◽  
Cone Photoreceptors ◽  
Cone Mosaic ◽  
Automated Technique ◽  
Healthy Eyes ◽  
Cone Density

Purpose To assess the signal composition of cone photoreceptors three-dimensionally in healthy retinas using adaptive optics optical coherence tomography (AO-OCT). Methods Study population. Twenty healthy eyes of ten subjects (age 23 to 67). Procedures. After routine ophthalmological assessments, eyes were examined using AO-OCT. Three-dimensional volumes were acquired at 2.5° and 6.5° foveal eccentricity in four main meridians (superior, nasal, inferior, temporal). Cone densities and signal compositions were investigated in four different planes: the cone inner segment outer segment junction (IS/OS), the cone outer segment combined with the IS/OS (ISOS+), the cone outer segment tips (COST) and full en-face plane (FEF) combining signals from all mentioned cone layers. Additionally, reliability of a simple semi-automated approach for assessment of cone density was tested. Main outcome measures. Cone density of IS/OS, IS/OS+, COST and FEF. Qualitative depiction and composition of each cone layer. Inter-rater agreement of cone density measurements. Results Mean overall cone density at all eccentricities was highest at the FEF plane (21.160/mm2), followed by COST (20.450/mm2), IS/OS+ (19.920/mm2) and IS/OS (19.530/mm2). The different meridians and eccentricities had a significant impact on cone density, with lower eccentricity resulting in higher cone densities (p≤.001), which were highest at the nasal, then temporal, then inferior and then superior meridian. Depiction of the cone mosaic differed between all 4 layers regarding signal size and packing density. Therefore, different cone layers showed evident but not complete signal overlap. Using the semi-automated technique for counting of cone signals achieved high inter-rater reliability (ICC > .99). Conclusions In healthy individuals qualitative and quantitative changes in cone signals are found not only in different eccentricities and meridians, but also within different photoreceptor layers. The variation between cone planes has to be considered when assessing the integrity of cone photoreceptors in healthy and diseased eyes using adaptive optics technology.

scholarly journals Evaluating outer segment length as a surrogate measure of peak foveal cone density

2017 ◽  
Vol 130 ◽  
pp. 57-66 ◽  
Author(s):  
Melissa A. Wilk ◽  
Brandon M. Wilk ◽  
Christopher S. Langlo ◽  
Robert F. Cooper ◽  
Joseph Carroll
Keyword(s):  
Outer Segment ◽  
Segment Length ◽  
Surrogate Measure ◽  
Cone Density

scholarly journals Cone photoreceptor dysfunction in retinitis pigmentosa revealed by optoretinography

2021 ◽  
Vol 118 (47) ◽  
pp. e2107444118
Author(s):  
Ayoub Lassoued ◽  
Furu Zhang ◽  
Kazuhiro Kurokawa ◽  
Yan Liu ◽  
Marcel T. Bernucci ◽  
...  
Keyword(s):  
Retinitis Pigmentosa ◽  
Adaptive Optics ◽  
Vision Loss ◽  
Photoreceptor Cells ◽  
Segment Length ◽  
Cone Photoreceptor ◽  
Cone Cells ◽  
Common Group ◽  
Cone Density

Retinitis pigmentosa (RP) is the most common group of inherited retinal degenerative diseases, whose most debilitating phase is cone photoreceptor death. Perimetric and electroretinographic methods are the gold standards for diagnosing and monitoring RP and assessing cone function. However, these methods lack the spatial resolution and sensitivity to assess disease progression at the level of individual photoreceptor cells, where the disease originates and whose degradation causes vision loss. High-resolution retinal imaging methods permit visualization of human cone cells in vivo but have only recently achieved sufficient sensitivity to observe their function as manifested in the cone optoretinogram. By imaging with phase-sensitive adaptive optics optical coherence tomography, we identify a biomarker in the cone optoretinogram that characterizes individual cone dysfunction by stimulating cone cells with flashes of light and measuring nanometer-scale changes in their outer segments. We find that cone optoretinographic responses decrease with increasing RP severity and that even in areas where cone density appears normal, cones can respond differently than those in controls. Unexpectedly, in the most severely diseased patches examined, we find isolated cones that respond normally. Short-wavelength–sensitive cones are found to be more vulnerable to RP than medium- and long-wavelength–sensitive cones. We find that decreases in cone response and cone outer-segment length arise earlier in RP than changes in cone density but that decreases in response and length are not necessarily correlated within single cones.

scholarly journals Macular Pigment Optical Density and Photoreceptor Outer Segment Length as Predisease Biomarkers for Age-Related Macular Degeneration

2020 ◽  
Vol 9 (5) ◽  
pp. 1347 ◽  
Author(s):  
Norihiro Nagai ◽  
Sakiko Minami ◽  
Misa Suzuki ◽  
Hajime Shinoda ◽  
Toshihide Kurihara ◽  
...  
Keyword(s):  
Macular Degeneration ◽  
Optical Density ◽  
Outer Segment ◽  
Macular Pigment ◽  
Age Related Macular Degeneration ◽  
Segment Length ◽  
Macular Pigment Optical Density ◽  
Photoreceptor Outer Segment ◽  
Age Related ◽  
Fellow Eyes

To explore predisease biomarkers, which may help screen for the risk of age-related macular degeneration (AMD) at very early stages, macular pigment optical density (MPOD) and photoreceptor outer segment (PROS) length were analyzed. Thirty late AMD fellow eyes, which are at high risk and represent the predisease condition of AMD, were evaluated and compared with 30 age-matched control eyes without retinal diseases; there was no early AMD involvement in the AMD fellow eyes. MPOD was measured using MPS2® (M.E. Technica Co. Ltd., Tokyo, Japan), and PROS length was measured based on optical coherence tomography images. MPOD levels and PROS length in the AMD fellow eyes were significantly lower and shorter, respectively, than in control eyes. MPOD and PROS length were positively correlated in control eyes (R = 0.386; p = 0.035) but not in AMD fellow eyes. Twenty (67%) AMD fellow eyes met the criteria of MPOD < 0.65 and/or PROS length < 35 μm, while only five (17%) control eyes did. After adjusting for age and sex, AMD fellow eyes more frequently satisfied the definition (p < 0.001; 95% confidence interval, 3.50–60.4; odds ratio, 14.6). The combination of MPOD and PROS length may be a useful biomarker for screening predisease AMD patients, although further studies are required in this regard.

The relationship between ambient lighting conditions, absolute dark-adapted thresholds, and rhodopsin in black and hypopigmented mice

2004 ◽  
Vol 21 (6) ◽  
pp. 925-934 ◽  
Author(s):  
GERARD H. DALY ◽  
JESSICA M. DILEONARDO ◽  
NATALIE R. BALKEMA ◽  
GRANT W. BALKEMA
Keyword(s):  
Bright Light ◽  
Visual Sensitivity ◽  
Segment Length ◽  
Single Strain ◽  
Photoreceptor Layer ◽  
Lighting Conditions ◽  
Ambient Lighting ◽  
Dim Light ◽  
Albino Mice ◽  
The Relationship

Significant variation in absolute dark-adapted thresholds is observed both within and between strains of mice with differing ocular pigmentation levels. Differences in threshold within a single strain are related to the Williams' photostasis effect, that is, photoreceptor rhodopsin levels are dependent upon ambient lighting conditions. To examine threshold differences among strains, we equalized rhodopsin levels by maintaining albino mice (c2J/c2J) at 2 × 10−4 cd/m2 (dim light) and black mice at 2 × 102 cd/m2 (bright light). This resulted in ocular rhodopsin levels for albino mice (albino—dim) of 494 ± 11 pmoles/eye and rhodopsin levels for black mice (black—bright) of 506 ± 25 pmoles/eye. For comparison, rhodopsin levels in black mice maintained in dim light are 586 ± 46 pmoles/eye and 217 ± 46 pmoles/eye in albino mice maintained in bright light. We found similar dark-adapted thresholds (6.38 log cd/m2vs. 6.47 log cd/m2)) in albino and black mice with equivalent rhodopsin determined with a water maze test. This suggests that dark-adapted thresholds are directly related to rhodopsin levels regardless of the level of ocular melanin. The number of photoreceptors, photoreceptor layer thickness, and outer segment length did not differ significantly between albino (dark) and black mice (bright). These results demonstrate that the visual sensitivity defect found in hypopigmented animals is secondary to abnormal rhodopsin regulation and that hypopigmented animals have either an improper input to the photostasis mechanism or that the photostasis mechanism is defective.

scholarly journals Distribution of cone density, spacing and arrangement in adult healthy retinas with adaptive optics flood illumination

PLoS ONE ◽  
2018 ◽  
Vol 13 (1) ◽  
pp. e0191141 ◽  
Author(s):  
Richard Legras ◽  
Alain Gaudric ◽  
Kelly Woog
Keyword(s):  
Adaptive Optics ◽  
Cone Density

scholarly journals Comparison of photoreceptor outer segment length in diabetic and idiopathic epiretinal membranes

Eye ◽  
2015 ◽  
Vol 29 (11) ◽  
pp. 1446-1452 ◽  
Author(s):  
K Yüksel ◽  
Y Karaküçük ◽  
A Özkaya ◽  
G Pekel ◽  
Ö Baz ◽  
...  
Keyword(s):  
Outer Segment ◽  
Segment Length ◽  
Photoreceptor Outer Segment ◽  
Epiretinal Membranes

The ageing photoreceptor

2007 ◽  
Vol 24 (2) ◽  
pp. 151-155 ◽  
Author(s):  
ALEXANDER CUNEA ◽  
GLEN JEFFERY
Keyword(s):  
Aging Process ◽  
Outer Segment ◽  
Retinal Disease ◽  
Segment Length ◽  
Rod Photoreceptor ◽  
Retinal Neurons ◽  
Rod Photoreceptors ◽  
Outer Segments ◽  
Age Related ◽  
Similar Density

With age many retinal neurons are lost. In humans the rod photoreceptor population in the perimacular region is subject to approximately 30% loss over life. Those that remain have been reported to suffer from extensive convolutions and localized swellings of their outer segments abnormally increasing their disc content and outer segment length. Here we examine quantitatively age-related changes in rat rod photoreceptors. The rat retina is ∼97% rod dominated. Here, aged rods showed significant reductions in outer segment length. The discs in their outer segments had a similar density, irrespective of whether they were young or old, however, in aged animals a higher proportion were misregistered. Surprisingly, in all of the tissue examined, we found no evidence for any convolution of outer segments or localized swelling as reported in humans, rather all remained straight. There are methodological differences between the research reported here and that undertaken on human retinae. There are also major differences in overall retinal architecture between humans and rodents that could contribute to differences in the aging process of individual cells. If it is the case that individual photoreceptors age differently in rodents compared to humans, it may pose significant problems for the use of this animal model in studies of ageing and age related outer retinal disease.

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