Parapapillary atrophy in optic neuropathies: Histology and clinical relevance

Parapapillary atrophy is one of the parameters of the optic nerve head area which are assessed during the ophthalmoscopic examination particularly useful to characterize glaucomatous optic neuropathy. Optical coherence tomography evaluation provides high-resolution images of the optic nerve head and surrounding area, and can be used to study parapapillary atrophy. Different parapapillary atrophy zones were described depending on their histological features and research has been conducted to investigate the possible association between the presence and/ or size of parapapillary atrophy zones and several optic nerve disorders. In this review we discuss the histology and the clinical findings related to parapapillary atrophy in patients with glaucomatous optic neuropathy, non-glaucomatous optic neuropathies (e.g. arteritic and non-arteritic anterior ischemic optic neuropathies; suprasellar and parasellar tumors), and other ocular conditions (e.g. high myopia; age-related macular degeneration). Two different histologic classifications were identified. Parapapillary atrophy was demonstrated in glaucoma and glaucoma-like neuropathies, but not in other types of optic nerve disorders.

Optimized-Unet: Novel Algorithm for Parapapillary Atrophy Segmentation

In recent years, an increasing number of people have myopia in China, especially the younger generation. Common myopia may develop into high myopia. High myopia causes visual impairment and blindness. Parapapillary atrophy (PPA) is a typical retinal pathology related to high myopia, which is also a basic clue for diagnosing high myopia. Therefore, accurate segmentation of the PPA is essential for high myopia diagnosis and treatment. In this study, we propose an optimized Unet (OT-Unet) to solve this important task. OT-Unet uses one of the pre-trained models: Visual Geometry Group (VGG), ResNet, and Res2Net, as a backbone and is combined with edge attention, parallel partial decoder, and reverse attention modules to improve the segmentation accuracy. In general, using the pre-trained models can improve the accuracy with fewer samples. The edge attention module extracts contour information, the parallel partial decoder module combines the multi-scale features, and the reverse attention module integrates high- and low-level features. We also propose an augmented loss function to increase the weight of complex pixels to enable the network to segment more complex lesion areas. Based on a dataset containing 360 images (Including 26 pictures provided by PALM), the proposed OT-Unet achieves a high AUC (Area Under Curve) of 0.9235, indicating a significant improvement over the original Unet (0.7917).

Characteristics of Optic Disc and Visual Field Changes in Patients with Thyroid-Associated Orbitopathy and Open-Angle Glaucoma

This study aimed to characterize the changes in the visual field (VF) patterns and disc morphology of patients with thyroid-associated orbitopathy (TAO) and open-angle glaucoma (OAG). A retrospective review of the medical records at the Tri-Service General Hospital in Taiwan identified 396 eyes of 198 patients with thyroid-associated glaucoma. A final follow-up of VF examination in 140 eyes revealed 114 eyes with VF defects, indicating disease progression. The characteristics of and changes in disc morphology, optical coherence tomography findings, and VF defects were statistically analyzed. The most common VF defects at the initial diagnosis and the end of the follow-up period were inferior partial arcuate (17%) and paracentral (15%) defects, respectively. The most common VF defect in patients with unspecific disc signs was an unspecific scotoma (13%). The most common optic disc feature was disc cupping (51%), followed by parapapillary atrophy (48%). The most frequent location of nerve fiber layer thinning was the inferotemporal region (48%). VF defects showed a significantly more pronounced progression in the non-nerve fiber bundle group than in the nerve fiber bundle group (p < 0.001). This study details the characteristics and progression of disc morphology and VF defects in patients with TAO and OAG.

Central retinal vascular trunk deviation in unilateral normal-tension glaucoma

Purpose To investigate whether the position of the central retinal vascular trunk (CRVT), as a surrogate of lamina cribrosa (LC) offset, was associated with the presence of glaucoma in normal-tension glaucoma (NTG) patients. Methods The position of the CRVT was measured as the deviation from the center of the Bruch’s membrane opening (BMO), as delineated by spectral-domain optical coherence tomography imaging. The offset index was calculated as the distance of the CRVT from the BMO center relative to that of the BMO margin. The angular deviation of CRVT was measured with the horizontal nasal midline as 0° and the superior location as a positive value. The offset index and angular deviation were compared between glaucoma and fellow control eyes within individuals. Results NTG eyes had higher baseline intraocular pressure (P = 0.001), a larger β-zone parapapillary atrophy area (P = 0.013), and a larger offset index (P<0.001). In a generalized linear mixed-effects model, larger offset index was the only risk factor of NTG diagnosis (OR = 31.625, P<0.001). A generalized estimating equation regression model revealed that the offset index was larger in the NTG eyes than in the control eyes for all ranges of axial length, while it was the smallest for the axial length of 23.4 mm (all P<0.001). Conclusions The offset index was larger in the unilateral NTG eyes, which fact is suggestive of the potential role of LC/BMO offset as a loco-regional susceptibility factor.

Ten-year-and-beyond longitudinal change of ß-zone parapapillary atrophy in glaucoma: association with retinal nerve fibre layer defect

BackgroundTo investigate the longitudinal change of localised retinal nerve fibre layer (RNFL) defects associated with change of ß-zone parapapillary atrophy (PPA) in primary open-angle glaucoma (POAG) eyes.MethodsPOAG patients with a localised RNFL defect and ß-zone PPA who had undergone disc/RNFL photography at 1-year intervals for 10 years or longer were enrolled. The topographic parameters of ß-zone PPA (area, maximal radial extent and angular extent around disc) were measured. Progression of RNFL defect was defined as widening of defect and/or appearance of new defect. The factors associated with progression of RNFL defect were assessed by OR using multivariable logistic regression.ResultsA total of 209 patients (209 eyes) with POAG were included (mean: 54 years old). Over the course of 11.5±2.3-year follow-up period, progression of RNFL defect was detected in 114 eyes (54.5%). Enlargement of PPA parameters (area and angular extent) was significantly more common in patients with RNFL defect progression than in eyes without progression (all p<0.001, respectively). Widening of radial extent did not show a significant difference in both groups (p=0.61). Increment of angular extent was in the direction of RNFL defect progression in 82.1% of eyes. Progression of RNFL defect was significantly associated with disc haemorrhage (OR: 6.653, p<0.001), enlargement of PPA area (OR: 4.114, p=0.004) and angular extent (OR: 6.572, p<0.001).ConclusionsProgression of RNFL defect is associated with increment of angular extent of PPA in POAG eyes.

Characteristics of Fundal Changes in Fundus Tessellation in Young Adults

Purpose: To explore the characteristics and associated factors of fundus tessellation, especially the alternation of choroidal thickness among different degrees of tessellated fundus in young adults.Design: Cross-sectional, population-based study.Methods: A total of 796 students were included in the study and underwent comprehensive ophthalmic examinations, including anterior segment examinations and swept-source optical coherence tomography (OCT) measurements. The degree of tessellated fundus was assessed by fundus photographs applying an early treatment of diabetic retinopathy study grid to evaluate the location of fundus tessellation and then divided into five groups. The topographic variation and factors, tilted disc ratio, parapapillary atrophy (PPA), retinal thickness (ReT), choroidal thickness (ChT), and subfoveal scleral thickness (SST) related to tessellated fundus were analyzed.Results: Compared to normal fundus, tessellated fundus had a lower spherical equivalent (SE) (p &lt; 0.0001), worse best-corrected visual acuity (BCVA)(p = 0.043), longer axial length (AL) (p &lt; 0.0001), thinner retina (p &lt; 0.0001), thinner (p &lt; 0.0001) choroid, and thinner sclera in center fovea (p = 0.0035). Among all subfields of macular and peripapillary regions, center fovea and macula-papillary region showed the most significant decrease in choroidal thickness. The proportion of fundus tessellation significantly increased with lower body weight index (BMI) (p = 0.0067), longer AL (p &lt; 0.0001), larger PPA(p = 0.0058), thinner choroid (p &lt; 0.0001), and thinner sclera (p &lt; 0.0001).Conclusions: Eyes showed more severe myopic morphological alternation with the increasement of proportion of fundus tessellation to the center fovea, including a significant decrease in both choroid and scleral thickness. Choroidal thinning may progress most rapidly in the macula-papillary region as fundus tessellation approaches to the center fovea.

Commentary review on peripapillary morphological characteristics in high myopia eyes with glaucoma: diagnostic challenges and strategies

The incidences of open angle glaucoma (OAG) and high myopia are increasing concomitantly. Considering the aging population and concurrent rapid increase in the number of individuals with myopia, the risk of visual defects caused by highly myopic OAG is likely to increase dramatically over the next few decades. However, precise screening and diagnosis of OAG is challenging because of the tilt and rotation of the optic disc, as well as extensive β-zone parapapillary atrophy in highly myopic eyes. Recent advances in optical coherence tomography (OCT) and OCT angiography (OCTA) technologies imply that both modalities are promising tools for the detection of highly myopic OAG. Notably, the diagnosis of OAG remains to be determined with the longitudinal changes of functional damages (e.g. visual field defect, visual electrophysiological changes). We herein describe some aspects of microvascular and microstructural pathology in patients with highly myopic OAG and proposes a framework for the development of novel diagnostic and therapeutic strategies.

Central Retinal Vascular Trunk Deviation in Unilateral Open-angle Glaucoma

Patients with unilateral open-angle glaucoma (OAG) have suffered glaucomatous optic neuropathy in one eye only despite shared systemic factors between two eyes. It suggests a locoregional susceptibility factor associated with glaucoma development. In this study, we measured the distance of the central retinal vascular trunk from the Bruch’s membrane opening (BMO) center relative to that of the BMO margin: the shift index, since it can be used as a surrogate of lamina cribrosa (LC) shift caused by different growth between retinal and scleral layers during eyeball expansion. The shift index was compared between OAG and fellow control eyes within individuals (129 OAG patients). Although OAG eyes also had higher baseline IOP, a larger β-zone parapapillary atrophy area, a larger shift index was the only risk factor of OAG diagnosis in a generalized linear mixed-effects model. Further, a generalized estimating equation regression model revealed that the shift index was larger in the OAG eyes than in the control eyes for all ranges of axial length, while it was the smallest for the axial length of 23.7 mm. Thus, a larger shift index and LC shift may act as a locoregional susceptibility factor for unilateral OAG eyes.

Topographic Relationship with a Retinal Nerve Fiber Layer Defect Differs between β-Zone and γ-Zone Parapapillary Atrophy

Introduction. γ-Zone parapapillary atrophy (PPA), an associated feature in myopic tilted optic disc, is considered to be relevant with glaucomatous optic nerve damage in myopic eyes. This study determines the topographic relationship of γ-zone PPA with a retinal nerve fiber layer defect. Purpose. To determine the topographic relationship of γ-zone PPA with a RNFL defect and to compare it with that of β-zone PPA. Design. Cross-sectional, observational study. Participants. Eighty-nine eyes from 89 patients with primary open-angle glaucoma who had β-zone PPA (n = 49) or γ-zone PPA (n = 40) and a single localized RNFL defect. Methods. PPA was classified according to the presence or absence of Bruch’s membrane on the PPA bed in spectral-domain optical coherence tomography. The angular location of the point of maximum radial extent of PPA (PMRE) and the RNFL defect was measured with the fovea-disc axis set at 0° in color and red-free fundus photographs. Main Outcome Measures. Angular distance between the RNFL defect and the PMRE. Results. There was no significant intergroup difference in the extent of the RNFL defect (P=0.920). The angular distance between the RNFL defect and the PMRE was significantly greater in γ-zone than β-zone PPA (26.49 ± 17.27° vs. 60.31 ± 17.12°, P<0.001). The angular location of the PMRE was significantly correlated with the location of the RNFL defect in the β-zone group (r = 0.822, P<0.001) but not in the γ-zone group. The RNFL defect was mostly located near the edge of γ-zone PPA in the γ-zone group (10.56 ± 9.47°). Conclusions. An RNFL defect was observed near the edge of PPA in eyes with γ-zone PPA, in contrast to it being close to the PMRE in eyes with β-zone PPA.