Is OS junction an ellipsoid?
2) The ellipsoid zone (EZ), which was previously referred as the photoreceptor inner segment/outer segment (IS/OS) junction, is now thought to be formed mainly by mitochondria within the ellipsoid layer of the outer portion of the inner segments of the photoreceptors.
What does geographic atrophy look like on OCT?
SD-OCT scans of geographic atrophy, reveals RPE thinning, loss of EPIS and COST lines, depression of the inner retinal layers as the outer layers are loss, and increase visibility of Bruch’s membrane and the choroid.
Is OS disruption in OCT?
We demonstrated that the presence of CME and IS/OS disruption detected with OCT correlated with a poorer BCVA in idiopathic ERMs. The visual acuity of most patients was stable during the follow-up period. The presence of CME in OCT represented a predictor of vision deterioration for patients with idiopathic ERMs.
What is Hyperreflectivity in OCT?
The hyperreflective foci or dots are two different terms used to call abnormal hyperreflective elements detected in OCT scans. The HRDs are scattered, punctiform, small in size, mainly located in the outer retinal layers and/or around pockets of fluid accumulation and are typically not confluent [3].
What is ellipsoid layer?
The ellipsoid zone (EZ) (Figure 1B) is considered to be formed mainly by mitochondria within the ellipsoid layer of the outer portion of the inner segments of the photoreceptors. However, it was previously known as the junction between the photoreceptor IS/OS).
What is Myoid zone?
The Photoreceptor Inner Segment Myoid Zone is the portion of the inner segment of photoreceptors that is between the mitocondria-rich ellipsoid zone and the cell body / nucleus of the photoreceptor inner segments. This myoid zone is rich in protein synthesis apparatus, which results in poor reflectivity on the OCT.
Is geographic atrophy the same as AMD?
Geographic atrophy (GA) is a chronic progressive degeneration of the macula, as part of late-stage age-related macular degeneration (AMD). The disease is characterized by localized sharply demarcated atrophy of outer retinal tissue, retinal pigment epithelium and choriocapillaris.
How quickly does geographic atrophy progress?
Usually, once GA starts, the region of atrophy expands slowly over several years until the central vision is lost and vision is about 20/200.
What is Hyporeflective?
Hyporeflectivity between the RPE and retina is a common indication of subretinal fluid. Outer retina. Fluid often accumulates in this location in macular edema related to inflammation, diabetes and vascular abnormalities such as vein occlusion or choroidal neovascularization.
What are Hyperreflective foci?
Hyperreflective foci (HRF) is a term coined to depict hyperreflective dots or roundish lesions within retinal layers visualized through optical coherence tomography (OCT).
What is October Interdigitation zone?
The interdigitation zone (IZ) (Figure 1B) is considered to be the contact cylinders formed by the apices of the RPE cells that encase part of outer segments of the cones. It was previously called the cone outer segment tips (COST) and rod outer segment tips (ROST), and its differentiation from RPE layer is difficult.
What is the Myoid zone on OCT?
What does a person with geographic atrophy see?
Geographic atrophy is a chronic progressive degeneration of the macula and can be seen as part of late-stage age-related macular degeneration (AMD). The condition leads to central scotomas and permanent loss of visual acuity.
Is geographic atrophy dry AMD?
Geographic atrophy (GA) is an advanced form of dry age-related macular degeneration (commonly referred to as AMD). AMD is a disease that affects part of the back of the eye called the macula.
What is disc OCT?
Optical coherence tomography (OCT) is able to determine the optic disc margin automatically. The aim of this study was to investigate the accuracy of the automatic OCT optic nerve head measurements in the presence of peripapillary atrophy.
What is RNFL?
The retinal nerve fiber layer (RNFL) is composed primarily of ganglion cell axons before they coalesce in the optic nerve. Early postmortem studies by Hinton et al. (1986) demonstrated the axonal degeneration of the optic nerve and decreased thickness of the RNFL in AD patients.
What does Hyperreflective mean?
Retinal hyperreflective foci (HF) is defined as small discrete, well-circumscribed, dot-shaped lesion, with equal or greater reflectivity than the retinal pigment epithelium (RPE) band on spectral domain optical coherence tomography (SD-OCT) [12].
How do you describe October?
Optical coherence tomography (OCT) is an optical analog of ultrasound imaging that uses low coherence interferometry to produce cross-sectional images of the retina. It captures optical scattering from the tissue to decode spatial details of tissue microstructures.
What is the ellipsoid zone in optical coherence tomography?
Emergence of the high-resolution optical coherence tomography has allowed better delineation of retinal layers, and many of the anatomical correlations of these layers have now been agreed upon. However, some anatomical correlates still remain contentious, such as the second hyper-reflective band, which is now termed ellipsoid zone.
What is the difference between ellipsoid zone and RPE?
The ellipsoid zone is a consensus term based on current understanding of OCT lexicon and landmarks. It represents the inner portion of the photoreceptor layer that is densely packed with mitochondria. Meanwhile the RPE is a longstanding and well-described term referring to the cell layer that photoreceptors use for nourishment (among other roles).
What does an Oct scan of the eye show?
OCT scans show drusen regression and change in the ellipsoid zone (EZ) integrity at the 12-month visit and the recovery of the EZ integrity at the 24-month visit. The recovery of the EZ integrity is associated with the improvement in the mfERG implicit time, particularly at the central and temporal retina.
What is the axial resolution of a TD OCT?
In 1991, a TD-OCT was capable of producing a single A-scan in 1.25 s with an axial resolution of 17 µm. 25 The inner retina hyper-reflective zone was reported to represent the nerve fibre layer, but the outer retina hypo-reflective zone was not further described.