Correlation of Outer Nuclear Layer Thickness With Cone Density Values in Patients With Retinitis Pigmentosa and Healthy Subjects

Menghini, Moreno; Lujan, Brandon J.; Zayit‐Soudry, Shiri; Syed, Reema; Porco, Travis C.; Bayabo, Kristine; Carroll, Joseph; Roorda, Austin; Duncan, Jacque L.

doi:10.1167/iovs.14-15521

Cited by 63 publications

(60 citation statements)

References 29 publications

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“…Previous groups have reported increased cone spacing and/or decreased cone density in subjects with RP. 21,24–27,29–31 In our cohort, we found a small but statistically insignificant decrease in the density of waveguiding foveal cones in RP. In contrast, a significant decrease in foveal cone density was seen in subjects with Usher syndrome.…”

Section: Discussionmentioning

confidence: 43%

“…14–16 It has been shown in a number of retinal conditions that significant photoreceptor disruption can be seen with AO imagery even when photoreceptor bands appear intact on OCT. 17–22 Numerous groups have examined the cone mosaic in RP using flood-illuminated AO 23,24 and confocal AO scanning light ophthalmoscopy (AOSLO). 25–31 In the presence of normal outer retinal architecture on OCT, foveal/parafoveal cone density in RP subjects can range from normal to severely decreased. 25,27,28,30,31 Furthermore, visual function can remain within normal limits even when the cone mosaic is disrupted.…”

mentioning

confidence: 99%

“…25–31 In the presence of normal outer retinal architecture on OCT, foveal/parafoveal cone density in RP subjects can range from normal to severely decreased. 25,27,28,30,31 Furthermore, visual function can remain within normal limits even when the cone mosaic is disrupted. 21,27 These findings further highlight the superior sensitivity of AO imaging tools for assessing rod and cone mosaic structure in RP.…”

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confidence: 99%

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Assessing Photoreceptor Structure in Retinitis Pigmentosa and Usher Syndrome

Sun

Johnson

Langlo

et al. 2016

Invest. Ophthalmol. Vis. Sci.

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PurposeThe purpose of this study was to examine cone photoreceptor structure in retinitis pigmentosa (RP) and Usher syndrome using confocal and nonconfocal split-detector adaptive optics scanning light ophthalmoscopy (AOSLO).MethodsNineteen subjects (11 RP, 8 Usher syndrome) underwent ophthalmic and genetic testing, spectral-domain optical coherence tomography (SD-OCT), and AOSLO imaging. Split-detector images obtained in 11 subjects (7 RP, 4 Usher syndrome) were used to assess remnant cone structure in areas of altered cone reflectivity on confocal AOSLO.ResultsDespite normal interdigitation zone and ellipsoid zone appearance on OCT, foveal and parafoveal cone densities derived from confocal AOSLO images were significantly lower in Usher syndrome compared with RP. This was due in large part to an increased prevalence of non-waveguiding cones in the Usher syndrome retina. Although significantly correlated to best-corrected visual acuity and foveal sensitivity, cone density can decrease by nearly 38% before visual acuity becomes abnormal. Aberrantly waveguiding cones were noted within the transition zone of all eyes and corresponded to intact inner segment structures. These remnant cones decreased in density and increased in diameter across the transition zone and disappeared with external limiting membrane collapse.ConclusionsFoveal cone density can be decreased in RP and Usher syndrome before visible changes on OCT or a decline in visual function. Thus, AOSLO imaging may allow more sensitive monitoring of disease than current methods. However, confocal AOSLO is limited by dependence on cone waveguiding, whereas split-detector AOSLO offers unambiguous and quantifiable visualization of remnant cone inner segment structure. Confocal and split-detector thus offer complementary insights into retinal pathology.

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Section: Discussionmentioning

confidence: 43%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Assessing Photoreceptor Structure in Retinitis Pigmentosa and Usher Syndrome

Sun

Johnson

Langlo

et al. 2016

Invest. Ophthalmol. Vis. Sci.

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“…By displacing the OCT beam laterally, the collected back-scattered intensity of HFL increased on the opposite side of the foveal pit from the pupil entry offset, resulting in enhanced OCT visibility due to nearly normal illumination relative to HFL fibers in that region. Using eccentric pupil entry positions in a technique called Directional OCT, visualization of HFL enabled anatomically correct ONL thickness measurements [15,16]. However, similar to previous studies, the pupil entry position manual displacement was subject to patient motion and operator misalignment.…”

Section: Introductionmentioning

confidence: 77%

Pupil tracking optical coherence tomography for precise control of pupil entry position

Carrasco-Zevallos

Nankivil

Keller

et al. 2015

Biomed. Opt. Express

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Abstract:To maximize the collection efficiency of back-scattered light, and to minimize aberrations and vignetting, the lateral position of the scan pivot of an optical coherence tomography (OCT) retinal scanner should be imaged to the center of the ocular pupil. Additionally, several retinal structures including Henle's Fiber Layer (HFL) exhibit reflectivities that depend on illumination angle, which can be controlled by varying the pupil entry position of the OCT beam. In this work, we describe an automated method for controlling the lateral pupil entry position in retinal OCT by utilizing pupil tracking in conjunction with a 2D fast steering mirror placed conjugate to the retinal plane. We demonstrate that pupil tracking prevents lateral motion artifacts from impeding desired pupil entry locations, and enables precise pupil entry positioning and therefore control of the illumination angle of incidence at the retinal plane. We use our prototype pupil tracking OCT system to directly visualize the obliquely oriented HFL.

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“…Moreno et al performed D-OCT measurements utilizing the Heidelberg Spectralis system by laterally moving the OCT arm while observing the HFL and acquiring images when the HFL/ONL interface was unambiguously visible. 23 An advantage of the Cirrus system in our study was that a novice operator could use the integrated pupil camera to facilitate D-OCT acquisition rather than having to interpret retinal anatomy while acquiring scans.…”

Section: Discussionmentioning

confidence: 99%

Directional Optical Coherence Tomography Reveals Reliable Outer Nuclear Layer Measurements

Tong¹,

Lujan²,

Zhou³

et al. 2016

Optom Vis Sci

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Purpose Directional Optical Coherence Tomography (D-OCT) is a method used to optically segment and identify the outer nuclear layer (ONL) in vivo. The purpose of this study was to determine the repeatability and reproducibility of D-OCT ONL thickness measurements in healthy eyes. Methods Sixteen healthy eyes of sixteen subjects were imaged using the Cirrus SD-OCT. The OCT beam entry position was varied horizontally and vertically through the pupil, and cross-sectional images were obtained at baseline and 1-month follow-up by 2 observers. Detailed segmentation was performed to quantify the thickness of ONL without the inclusion of overlying Henle Fiber Layer. Inter-observer, intra-observer, and inter-visit variability was evaluated using Bland-Altman and coefficient of variation analysis for each category. Results All sixteen eyes were successfully imaged, registered, and segmented. The maximum mean (SD) inter-operator difference was 2.6 (4.8) µm. The maximum mean (SD) intra-operator difference was 2.4 (5.3) µm. There was no statistically significant difference in ONL measurements detected between baseline and follow-up (P > 0.05). The mean (SD) differences measured across visits by one operator varied from −1.6 (3.1) to 1.1 (6.1) µm. The mean (SD) coefficient of variance (CV%) for all sectors with horizontal orientation was 9.1% (2.3%), 10.1% (2.5%), and 8.6% (2.3%) for inter-observer, intra-observer, and inter-visit, respectively. The mean (SD) coefficient of variance (CV%) for all sectors with vertical orientation was 8.3% (1.8%), 6.9% (1.4%), and 8.3% (2.1%) for inter-observer, intra-observer, and inter-visit, respectively. The majority of the variation of paired repeated measurements originated from between-subject variance. The within-subject variance accounted for less than 1% of the total variability. Conclusions ONL thickness measurements can be quantified with good repeatability and reproducibility using D-OCT. Identifying the magnitude of D-OCT variability among normal subjects will allow for improved development of future clinical studies that quantitatively track the progression of macular pathology.

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Correlation of Outer Nuclear Layer Thickness With Cone Density Values in Patients With Retinitis Pigmentosa and Healthy Subjects

Abstract: The ONL thickness and cone density were correlated in normal eyes and eyes with RP, but both were strongly correlated with retinal eccentricity, precluding estimation of cone density from ONL thickness. (ClinicalTrials.gov number, NCT00254605.).

Cited by 63 publications

References 29 publications

Assessing Photoreceptor Structure in Retinitis Pigmentosa and Usher Syndrome

Assessing Photoreceptor Structure in Retinitis Pigmentosa and Usher Syndrome

Pupil tracking optical coherence tomography for precise control of pupil entry position

Directional Optical Coherence Tomography Reveals Reliable Outer Nuclear Layer Measurements

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