Dataset Information

Evaluating Descriptive Metrics of the Human Cone Mosaic.

ABSTRACT: PURPOSE:To evaluate how metrics used to describe the cone mosaic change in response to simulated photoreceptor undersampling (i.e., cell loss or misidentification). METHODS:Using an adaptive optics ophthalmoscope, we acquired images of the cone mosaic from the center of fixation to 10° along the temporal, superior, inferior, and nasal meridians in 20 healthy subjects. Regions of interest (n = 1780) were extracted at regular intervals along each meridian. Cone mosaic geometry was assessed using a variety of metrics - density, density recovery profile distance (DRPD), nearest neighbor distance (NND), intercell distance (ICD), farthest neighbor distance (FND), percentage of six-sided Voronoi cells, nearest neighbor regularity (NNR), number of neighbors regularity (NoNR), and Voronoi cell area regularity (VCAR). The "performance" of each metric was evaluated by determining the level of simulated loss necessary to obtain 80% statistical power. RESULTS:Of the metrics assessed, NND and DRPD were the least sensitive to undersampling, classifying mosaics that lost 50% of their coordinates as indistinguishable from normal. The NoNR was the most sensitive, detecting a significant deviation from normal with only a 10% cell loss. CONCLUSIONS:The robustness of cone spacing metrics makes them unsuitable for reliably detecting small deviations from normal or for tracking small changes in the mosaic over time. In contrast, regularity metrics are more sensitive to diffuse loss and, therefore, better suited for detecting such changes, provided the fraction of misidentified cells is minimal. Combining metrics with a variety of sensitivities may provide a more complete picture of the integrity of the photoreceptor mosaic.

SUBMITTER: Cooper RF

PROVIDER: S-EPMC4898203 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature

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Evaluating Descriptive Metrics of the Human Cone Mosaic.

Cooper Robert F RF Wilk Melissa A MA Tarima Sergey S Carroll Joseph J

Investigative ophthalmology & visual science 20160601 7

<h4>Purpose</h4>To evaluate how metrics used to describe the cone mosaic change in response to simulated photoreceptor undersampling (i.e., cell loss or misidentification).<h4>Methods</h4>Using an adaptive optics ophthalmoscope, we acquired images of the cone mosaic from the center of fixation to 10° along the temporal, superior, inferior, and nasal meridians in 20 healthy subjects. Regions of interest (n = 1780) were extracted at regular intervals along each meridian. Cone mosaic geometry was a ...[more]

PMID: 27273598

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Project description:PurposeInvestigate in vivo cone photoreceptor structure in familial aniridia caused by deletion in the PAX6 gene to elucidate the complexity of between-individual variation in retinal phenotype.DesignDescriptive case-control study.ParticipantsEight persons with congenital aniridia (40-66 yrs) from 1 family and 33 normal control participants (14-69 yrs), including 7 unaffected family members (14-53 yrs).MethodsDNA was isolated from saliva samples and used in polymerase chain reaction analysis to amplify and sequence exons and intron or exon junctions of the PAX6 gene. High-resolution retinal images were acquired with OCT and adaptive optics scanning light ophthalmoscopy. Cone density (CD; in cones per square millimeter) and mosaic regularity were estimated along nasal-temporal meridians within the central 0° to 5° eccentricity. Horizontal spectral-domain OCT line scans were segmented to analyze the severity of foveal hypoplasia (FH) and to measure retinal layer thicknesses.Main outcomes and measuresWithin-family variability in macular retinal layer thicknesses, cone photoreceptor density, and mosaic regularity in aniridia compared with normal control participants.ResultsDNA sequencing revealed a known PAX6 mutation (IV2-2delA). Those with aniridia showed variable iris phenotype ranging from almost normal appearance to no iris. Four participants with aniridia demonstrated FH grade 2, 2 demonstrated grade 3 FH, and 1 demonstrated grade 4 FH. Visual acuity ranged from 0.20 to 0.86 logarithm of the minimum angle of resolution. Adaptive optics scanning light ophthalmoscopy images were acquired from 5 family members with aniridia. Foveal CD varied between 19 899 and 55 128 cones/mm2 with overlap between the foveal hypoplasia grades. Cone density was 3 standard deviations (SDs) or more less than the normal mean within 0.5°, 2 SDs less than the normal mean at 0.5° to 4°, and more than 1 SD less than the normal mean at 5° retinal eccentricity.ConclusionsThe results showed considerable variability in foveal development within a family carrying the same PAX6 mutation. This, together with the structural and functional variability within each grade of foveal hypoplasia, underlines the importance of advancing knowledge about retinal cellular phenotype in aniridia.

Dataset Information

Evaluating Descriptive Metrics of the Human Cone Mosaic.

Publications

Evaluating Descriptive Metrics of the Human Cone Mosaic.

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