OCT-Based Quantification and Classification of Optic Disc Structure in Glaucoma Patients

Abstract

PurposeTo objectively classify the optic discs of open-angle glaucoma (OAG) patients into Nicolela's four disc types, i.e., focal ischemic (FI), myopic (MY), senile sclerotic (SS), and generalized enlargement (GE), with swept-source optical coherence tomography (SS-OCT).MethodsThis study enrolled 113 eyes of 113 OAG patients (mean age: 62.5 ± 12.6; Humphrey field analyzer-measured mean deviation: -9.4 ± 7.3 dB). Newly developed software was used to quantify a total of 20 optic disc parameters in SS-OCT (DRI OCT-1, TOPCON) images of the optic disc. The most suitable reference plane (RP) above the plane of Bruch’s membrane opening was determined by comparing, at various RP heights, the SS-OCT-measured rim parameters and spectral-domain OCT-measured circumpapillary retinal nerve fiber layer thickness (cpRNFLT), with Pearson's correlation analysis. To obtain a discriminant formula for disc type classification, a training group of 72 eyes of 72 OAG patients and a validation group of 60 eyes of 60 OAG patients were set up.ResultsCorrelation with cpRNFLT differed with disc type and RP height, but overall, a height of 120 μm minimized the influence of disc type. Six parameters were most significant for disc type discrimination: disc angle (horizontal), average cup depth, cup/disc ratio, rim-decentering ratio, average rim/disc ratio (upper and lower nasal). Classifying the validation group with these parameters returned an identification rate of 80.0% and a Cohen’s Kappa of 0.73.ConclusionOur new, objective SS-OCT-based method enabled us to classify glaucomatous optic discs with high reproducibility and accuracy.

Microperimetry and optical coherence tomography imaging in the fellow eye of patients with unilateral focal ischaemic glaucoma

“…In conclusion, focal ischaemic glaucoma is characterised by early visual field deficits threatening fixation [2,7,24]. In patients with unilateral disease, early detection of disease in the fellow eye and the subsequent treatment is critical to prevent bilateral central scotomas, which may threaten reading or driving vision [9].…”

“…Focal ischaemic glaucoma is a disease subtype characterised by focal notching of the neuroretinal rim with a congruous visual field deficit, which threatens fixation early in the clinical course ("split-fixation" visual field defect) [2,3]. Female gender, earlier age of onset, recurrent optic disc haemorrhages and primary vascular dysregulation syndromes (nocturnal hypotension, vasospasm, migraine and Raynaud's phenomenon) are associated with the focal ischaemic glaucoma subtype [2][3][4][5][6][7].…”

Classification of optic disc shape in glaucoma using machine learning based on quantified ocular parameters

“…In this study, minors were not included. The patients were classified into Nicolela’s 4 types: focal ischemic (FI), generalized enlargement (GE), myopic (MY), and senile sclerotic (SS) with a method we have previously described [ 11 , 12 ]. The distinctive characteristics of each disc type include rim notching in FI, a diffusely enlarged, rounded cup in GE, a tilted disc and temporal crescent peripapillary atrophy (PPA) in MY, and shallow cupping and haloing in SS.…”

“…However, classification of the optic disc can sometimes be difficult because it relies on subjective assessment methods. Thus, we previously attempted to develop new, objective, and more accurate methods of classifying the optic disc, based on stereophotography [ 11 ] and optical coherence tomography (OCT) [ 12 ].…”

Analysis of OCT Images to Optimize Glaucoma Diagnosis

“…This result encouraged us to develop new parameters from the structural anatomy of the ONH. Previous studies have calculated the cup and disk area with some limitations [5], but here we calculated the total mean area of ONH surface, and our initial point of ROI selection was measured from disk to cup with minimum rim width demonstrated in Fig. 2(a) and all final images in Fig.…”