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To determine the factors significantly associated with anterior protrusion of the macula in eyes with a macula-off rhegmatogenous retinal detachment (RRD) and to determine the relationship between the intraretinal cystoid cavities (ICCs) and the anterior protrusion and function of the fovea. Retrospective cross-sectional study. Sixty-nine eyes of 69 patients with successfully reattached macula-off RRD were retrospectively analyzed. Six radial spectral-domain optical coherence tomographic (OCT) images were used to evaluate the effects of the ICCs on detached macula and to measure the angle of the retina at the macula as a parameter to evaluate the anterior protrusion of the detached retina. The findings were compared to other parameters. The mean angle of the retina at the macula was 143.1 ± 15.9° with a range of 108 to 172°. Preoperatively, 51 eyes (74%) had ICCs in the inner nuclear layer and/or the outer plexiform layer and Henle fiber layer complex, but none was present after surgery. Multivariate regression analyses revealed that the angle of the retina was significantly associated with the presence of ICCs (β = -0.637, P

Purpose:To perform a macular volumetric and topographic analysis of Henle fiber layer (HFL) from retinal scans acquired by directional optical coherence tomography.Methods:Thirty healthy eyes of 17 subjects were imaged using the Heidelberg spectral-domain optical coherence tomography (Spectralis, Heidelberg Engineering, Heidelberg, Germany) with varied horizontal and vertical pupil entry. Manual segmentation of HFL was performed from retinal sections of horizontally and vertically tilted optical coherence tomography images acquired within macular 20 × 20° area. Total HFL volume, mean HFL thickness, and HFL coverage area within Early Treatment for Diabetic Retinopathy Study grid were calculated from mapped images.Results:Henle fiber layer of 30 eyes were imaged, segmented and mapped. The mean total HFL volume was 0.74 ± 0.08 mm3with 0.16 ± 0.02 mm3, 0.18 ± 0.03 mm3, 0.17 ± 0.02 mm3, and 0.19 ± 0.03 mm3for superior, temporal, inferior, and nasal quadrants, respectively. The mean HFL thickness was 26.5 ± 2.9 µm. Central 1-mm macular zone had the highest mean HFL thickness with 51.0 ± 7.6 µm. The HFL coverage that have thickness equal or above to the mean value had a mean 10.771 ± 0.574 mm2of surface area.Conclusion:Henle fiber layer mapping is a promising tool for structural analysis of HFL. Identifying a normative data of HFL morphology will allow further studies to investigate HFL involvement in various ocular and systemic disorders. © 2022 Lippincott Williams and Wilkins. All rights reserved.

PURPOSE: To describe the appearance of concentric, fingerprint-like waves within the Henle Fiber Layer (HFL) using en face optical coherence tomography (OCT) in patients with tractional pathologies of the retina. METHODS: Retrospective analysis of 6 eyes of 6 patients imaged by OCT with volumetric slabs positioned at the level of the HFL. RESULTS: OCT data from 6 patients with tractional vitreoretinal pathology were reviewed. Concentric, fingerprint-like microwaves were visualized via en face OCT in all 6 study eyes at the level of the HFL. This finding resembled the finding of HFL waves previously noted histopathologically from force exerted on this layer. CONCLUSION: In retinal pathologies in which specific physical forces act upon the retina, volumetric OCT may permit visualization of en face concentric, fingerprint-like hyper-reflective rings within the HFL. This “fingerprint sign” may represent a biomechanical consequence of traction on the retina and allow clinical decision-making based on improved recognition of the existence of such traction. SUMMARY STATEMENT: Concentric hyper-reflective rings visualized by en face optical coherence tomography in patients with tractional pathologies of the retina may be caused by physical waves within the Henle Fiber Layer.

To determine if directional or anatomical changes in tissue reflectivity of Henle fiber layer (HFL) may influence flow detection on optical coherence tomography angiography (OCT-A).Cross-sectional analysis of consecutive cases undergoing OCT-A. Directional changes in visualization of HFL were either produced manually by moving the beam entrance within the pupil or observed occurring naturally because of tilting of the OCT line-scan within a myopic staphyloma. Areas of enhanced HFL visualization were identified on cross-sectional and en face structural OCT scans. Visualization of OCT-A flow within the superficial and the deep capillary plexuses were compared in areas with and without enhanced HFL reflectivity.Fifteen eyes from 9 patients were included, with a mean age of 49.6 ± 17.9 years. On OCT-A, retinal areas with enhanced HFL reflectivity produced manually or by scan tilting within myopic staphylomas showed no changes in the superficial capillary plexus flow. However, deep capillary plexus flow was altered by variable projection of the superficial flow onto the deeper retinal layers.Directional changes in HFL reflectivity can alter the detection of deep capillary plexus flow imaged with OCT-A by influencing the projection of superficial flow onto the deeper retinal layers. We recommend that clinicians minimize scan tilting during scan acquisition and be aware of this phenomenon in eyes with posterior staphyloma.

Purpose: OCT has been a technological breakthrough in the diagnosis, treatment, and follow-up of many ocular diseases, especially retinal and neuro-ophthalmologic pathologic conditions. Until now, several controversies have arisen over the specific cell types that the bands observed in the OCT represent, especially over the 4 outer retinal bands. Design: To correlate the 4 outer hyperreflective bands observed in the OCT with the histologic structures using human retinal sections and immunocytochemistry at the fovea level. Participants: Eyes from human donors. Methods: Vertical cryosections of human retinas were immunostained with antibodies specific for cones photoreceptors, bipolar cells, mitochondria, Müller cells, and retinal pigment epithelium (RPE) cells and were visualized using confocal microscopy. Main Outcome Measures: Morphological correlation between histology and OCT at the fovea level. Results: Triple immunolabeling allowed distinguishing between cells types and different cell compartments. Immunostaining with guanine nucleotide-binding protein β 3 (GNB3) and cellular retinaldehyde-binding protein (CRALBP) antibodies showed all retinal layers at the foveola, especially the separation between the outer nuclear layer and the Henle fiber layer. CRALBP and cytochrome C (Cyt C) immunolabeling revealed that hyperreflective bands 1 and 2, observed in the OCT, correspond to the outer limiting membrane and the cone ellipsoids, respectively, separated by the cone myoids. CRALBP, cytochrome C, and GNB3 showed that the RPE interdigitations extend along the entire external segment of the cones, we do not believe them to be the structure responsible for forming the third band. However, the identification of small fragments of cone outer segments within the RPE led us to characterize the third band as the cone phagosomes located in the top of the RPE. Finally, we propose that the fourth band corresponds to the accumulation of mitochondria at the basal portion of the RPE, as identified by cytochrome C immunoreactivity, and that the hyporeflective band between bands 3 and 4 corresponds to the RPE nuclei and melanosomes zone. Conclusions: This study proposes a new interpretation of the outer retinal bands that leads to a more accurate interpretation of OCT images, providing information about the health of cones and their relationship with the RPE, and could help to form a better understanding of retinal disease diagnosis and prognosis. Supported by the Ministerio de Economía y Competitividad (grant no.: MINECO-FEDER-BFU2015-67139-R); Instituto Carlos III (grant no.: ISCIII RETICS-FEDER RD12/0034/0010); Generalitat Valenciana (grant no.: prometeo 2016/158 [N.C.]); and the Ministerio de Educación (grant no.: FPU 14/03166 [I.O.-L.]).

Nonconfocal ultra-widefield scanning laser ophthalmoscopes produce foveal polarization artifacts that require normal Henle layer structure and are suppressed by center-involving diabetic macular edema. Polarization sensitivity is insufficient for the artifacts to be reliable clinical screening biomarkers., Purpose: Bowtie-shaped polarization artifacts are often present in nonconfocal ultra-widefield scanning laser ophthalmoscope (SLO) images. We studied these artifacts and evaluated their potential value as clinical biomarkers in screening for center-involving diabetic macular edema (DME). Methods: We performed a retrospective, observational, cohort study on 78 diabetic adult patients (143 eyes) who had spectral domain optical coherence tomography and nonmydriatic nonconfocal ultra-widefield SLO testing on the same day. Scanning laser ophthalmoscope green-only (532 nm), red-only (635 nm), and composite pseudocolor (532 plus 635 nm) images were examined for the presence of a foveal bowtie polarization artifact. Results: Polarization artifacts were absent in all but one eye with center-involving DME (32 of 33 eyes). Polarization artifacts were also absent in many eyes without center-involving DME (49 of 110 eyes in pseudocolor images). As clinical biomarkers of center-involving DME, artifact absence has high specificity (99, 100, and 98% for green, red, and pseudocolor images, respectively) but poor sensitivity (49, 31, and 40% for green, red, and pseudocolor images, respectively). Conclusion: Foveal bowtie-shaped polarization artifacts occur routinely in nonconfocal ultra-widefield SLO images. Their presence indicates preserved foveal Henle fiber layer structure. Contemporary nonconfocal ultra-widefield SLO images lack the sensitivity for their bowtie artifacts to serve as reliable biomarkers in screening for center-involving DME.

Directional optical coherence tomography (D-OCT) allows the visualization of the Henle fiber layer (HFL) in vivo. Here, we used D-OCT to characterize the HFL and outer nuclear layer (ONL) in albinism and examine the relationship between true foveal ONL and peak cone density.Horizontal D-OCT B-scans were acquired, registered, and averaged for 12 subjects with oculocutaneous albinism and 26 control subjects. Averaged images were manually segmented to extract HFL and ONL thickness. Adaptive optics scanning light ophthalmoscopy was used to acquire images of the foveal cone mosaic in 10 subjects with albinism, from which peak cone density was assessed.Across the foveal region, the HFL topography was different between subjects with albinism and normal controls. In particular, foveal HFL thickness was thicker in albinism than in normal controls (P0.0001), whereas foveal ONL thickness was thinner in albinism than in normal controls (P0.0001). The total HFL and ONL thickness was not significantly different between albinism and controls (P = 0.3169). Foveal ONL thickness was positively correlated with peak cone density in subjects with albinism (r = 0.8061, P = 0.0072).Foveal HFL and ONL topography are significantly altered in albinism relative to normal controls. Our data suggest that increased foveal cone packing drives the formation of Henle fibers, more so than the lateral displacement of inner retinal neurons (which is reduced in albinism). The ability to quantify foveal ONL and HFL may help further stratify grading schemes used to assess foveal hypoplasia.

A fovea is a pitted invagination in the inner retinal tissue (fovea interna) that overlies an area of photoreceptors specialized for high acuity vision (fovea externa). Although the shape of the vertebrate fovea varies considerably among the species, there are two basic types. The retina of many predatory fish, reptilians, and birds possess one (or two) convexiclivate fovea(s), while the retina of higher primates contains a concaviclivate fovea. By refraction of the incoming light, the convexiclivate fovea may function as image enlarger, focus indicator, and movement detector. By centrifugal displacement of the inner retinal layers, which increases the transparency of the central foveal tissue (the foveola), the primate fovea interna improves the quality of the image received by the central photoreceptors. In this review, we summarize ‒ with the focus on Muller cells of the human and macaque fovea ‒ data regarding the structure of the primate fovea, discuss various aspects of the optical function of the fovea, and propose a model of foveal development. The "Muller cell cone" of the foveola comprises specialized Muller cells which do not support neuronal activity but may serve optical and structural functions. In addition to the "Muller cell cone", structural stabilization of the foveal morphology may be provided by the 'z-shaped' Muller cells of the fovea walls, via exerting tractional forces onto Henle fibers. The spatial distribution of glial fibrillary acidic protein may suggest that the foveola and the Henle fiber layer are subjects to mechanical stress. During development, the foveal pit is proposed to be formed by a vertical contraction of the centralmost Muller cells. After widening of the foveal pit likely mediated by retracting astrocytes, Henle fibers are formed by horizontal contraction of Muller cell processes in the outer plexiform layer and the centripetal displacement of photoreceptors. A better understanding of the molecular, cellular, and mechanical factors involved in the developmental morphogenesis and the structural stabilization of the fovea may help to explain the (patho-) genesis of foveal hypoplasia and macular holes.

To present a selected case series of different phenotypes of the normal outer plexiform layer (OPL) visualized by optical coherence tomography (OCT).Five cases were selected to represent the spectrum of appearances of the OPL in this case series. Categorical descriptions of each manifestation were then developed. Additional SD-OCT scans were obtained from a normal volunteer to further support the hypothesis.The inner one-third of the OPL typically appears hyperreflective on OCT, while the outer two-thirds (Henle fiber layer) may have a more varied appearance. Six different phenotypes of Henle fiber layer reflectivity were noted in this series, and classified as: bright, columnar, dentate, delimited, indistinct, and dark. The brightness of the Henle fiber layer appears to depend on the geometric angle between the OCT light beam and the axonal fibers in this portion of the OPL. This angle appears to be a function of the natural orientation of the Henle fiber layer tissue (θN), the existence of subretinal pathology that alters the angle of the neurosensory retina (θ(P)), and the tilt angle of the tissue on the B-scan (θ(T)) due to decentered OCT acquisition.Since accurate interpretation of the OPL/ONL boundary is of vital importance to study the thickness of ONL, location of cystoid lesions, hyperreflective crescents over drusen, et al., our case series may aid better understanding of the OPL appearance in SD-OCT. In the absence of clear delineation, it may be most correct to refer to indistinct OPL and ONL together as the photoreceptor nuclear axonal complex (PNAC).

Author(s): Tong, Kevin K; Lujan, Brandon J; Zhou, Yixiu; Lin, Meng C | Abstract: PurposeDirectional 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.MethodsSixteen 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 two 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.ResultsAll 16 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 g 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.ConclusionsONL 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.

Purpose Directional optical coherence tomography (D-OCT) allows the visualization of the Henle fiber layer (HFL) in vivo. Here, we used D-OCT to characterize the HFL and outer nuclear layer (ONL) in albinism and examine the relationship between true foveal ONL and peak cone density. Methods Horizontal D-OCT B-scans were acquired, registered, and averaged for 12 subjects with oculocutaneous albinism and 26 control subjects. Averaged images were manually segmented to extract HFL and ONL thickness. Adaptive optics scanning light ophthalmoscopy was used to acquire images of the foveal cone mosaic in 10 subjects with albinism, from which peak cone density was assessed. Results Across the foveal region, the HFL topography was different between subjects with albinism and normal controls. In particular, foveal HFL thickness was thicker in albinism than in normal controls (P < 0.0001), whereas foveal ONL thickness was thinner in albinism than in normal controls (P < 0.0001). The total HFL and ONL thickness was not significantly different between albinism and controls (P = 0.3169). Foveal ONL thickness was positively correlated with peak cone density in subjects with albinism (r = 0.8061, P = 0.0072). Conclusions Foveal HFL and ONL topography are significantly altered in albinism relative to normal controls. Our data suggest that increased foveal cone packing drives the formation of Henle fibers, more so than the lateral displacement of inner retinal neurons (which is reduced in albinism). The ability to quantify foveal ONL and HFL may help further stratify grading schemes used to assess foveal hypoplasia.

Copyright © by Ophthalmic Communications Society, Inc. Purpose: The outer nuclear layer (ONL) contains photoreceptor nuclei, and its thickness is an important biomarker for retinal degenerations. Accurate ONL thickness measurements are obscured in standard optical coherence tomography (OCT) images because of Henle fiber layer (HFL). Improved differentiation of the ONL and HFL boundary is made possible by using directional OCT, a method that purposefully varies the pupil entrance position of the OCT beam. Methods: Fifty-seven normal eyes were imaged using multiple pupil entry positions with a commercial spectral domain OCT system. Cross-sectional image sets were registered to each other and segmented at the top of HFL, the border of HFL and the ONL and at the external limiting membrane. Thicknesses of the ONL and HFL were measured and analyzed. Results: The true ONL and HFL thicknesses varied substantially by eccentricity and between individuals. The true macular ONL thickness comprised an average of 54.6% of measurements that also included HFL. The ONL and HFL thicknesses at specific retinal eccentricities were poorly correlated. Conclusion: Accurate ONL and HFL thickness measurements are made possible by the optical contrast of directional OCT. Distinguishing these individual layers can improve clinical trial endpoints and assessment of disease progression.

This study quantified normal age-related changes to the photoreceptor axons in the central macula using the birefringent properties of the Henle fiber layer. A scanning laser polarimeter was used to acquire 15°×15° macular images in 120 clinically normal subjects, ranging in age from the third decade to the eighth. Raw image data of the macular cross were used to compute phase retardation maps associated with Henle fiber layer. Annular regions of interest ranging from 0.25° to 3° eccentricity and centered on the fovea were used to generate intensity profiles from the phase retardation data, which were then analyzed using sine curve fitting and Fast Fourier Transform (FFT). The amplitude of a 2f sine curve was used as a measure of macular phase retardation magnitude. For FFT analysis, the 2f amplitude, as well as the 4f, were normalized by the remaining FFT components. The amplitude component of the 2f curve fit and the normalized 2f FFT component decreased as a function of age, while the eccentricity of the maximum value for the normalized 2f FFT component increased. The phase retardation changes in the central macula indicate structural alterations in the cone photoreceptor axons near the fovea as a function of age. These changes result in either fewer cone photoreceptors in the central macula, or a change in the orientation of their axons. This large sample size demonstrates systematic changes to the central cone photoreceptor morphology using scanning laser polarimetry.

The outer plexiform layer (OPL) includes the photoreceptor synapse layer and Henle fiber layer (HFL) in the macular area. We attempted to improve optical coherence tomography imaging of the HFL by changing the angle of the measurement beam.Thirteen normal eyes underwent spectral domain optical coherence tomography. To focus the angle of the measurement beam perpendicular to the obliquely oriented HFL, the beam in the optical coherence tomography system was aimed at the periphery of the pupil.The cross-sectional image of the macular area was inclined right or left if the beam entered from the periphery of the pupil. The reflectivity of the OPL increased because of strong backscattering of light in the half of the macula that was tilted down in cross-sectional images. On the opposite side, the reflectivity of HFL (the outer two-thirds of the OPL) decreased compared with that of the outer nuclear layer, but the photoreceptor synapse layer (the inner one-third of the OPL) remained highly reflective. The mean thicknesses of the OPL that could be visualized 1.0 mm and 1.5 mm from the central fovea were 73.7 ± 7.0 μm and 64.1 ± 8.2 μm, respectively.Positioning the measurement beam perpendicular to HFL enhanced visualization performance.

The spatial distribution of macular birefringence was modeled to examine the contribution from the foveal Henle fiber layer, particularly cone axons. The model was tested in 20 normal subjects, age 17–55yr. Phase retardance due to Henle fibers was modeled for rings increasing in radius around the fovea, using a sinewave of two periods (2f). The 2f sinewave amplitude increased linearly with eccentricity for each individual, (p

Shadows cast by retinal blood vessels are represented in striate cortex of the squirrel monkey. Their pattern was exploited to generate a true retinotopic map of V1. For calibration, retinal landmarks were projected onto a tangent screen to measure their visual field location. Next, the retina was warped onto striate cortex, distorting it as necessary to match each retinal vessel to its cortical representation. Maps from four hemispheres of two normal adult squirrel monkeys were created and used to derive expressions for cortical magnification factor (M). A mean map was produced by averaging the individual maps. To address the controversial issue of whether the ratio of retinal ganglion cell (RGC) density to M is constant at all eccentricities, we stained a retinal whole mount from one of the two monkeys for Nissl substance. A ganglion cell density map was compiled by sampling the concentration of cells at 171 retinal points. Allowance was made for displaced amacrine cells and for the centripetal displacement of RGCs from central photoreceptors. After these corrections the V1 surface area and RGC density were compared at each eccentricity. The cortical representation of the macula was found to be amplified, even beyond the magnification expected from its high density of RGCs. For example, the central 4 degrees of visual field were allotted 27% of the surface area of V1 but were supplied by only 12% of RGCs. We conclude that, in monkey striate cortex, more tissue is allocated per ganglion cell for the analysis of information emanating from the macula as compared with the peripheral retina.

It seems quite certain that the visual entopic phenomenon called Haidinger’s brushes is a consequence of dichroism of the macular pigment; this dichroism is usually ascribed to orientation of the pigment molecules. An alternative explanation of the dichroism, an explanation that requires no orientation of pigment molecules, is investigated and shown to be feasible. Specifically, it is shown that form dichroism that is due to the structure of the Henle fiber layer can account for Haidinger’s brushes if the macular pigment is almost entirely confined to the Henle layer, if individual fibers have an index about 5% higher than that of the interfiber medium, and if the fibers form a tightly packed array.