Identifying and understanding optical coherence tomography artifacts that may be confused with glaucoma

Abstract

Optical coherence tomography is often used for detection of glaucoma as well as to monitor progression. This paper reviews the most common types of artifacts on the optical coherence tomography report that may be confused with glaucomatous damage. We mainly focus on anatomy-related artifacts in which the retinal layer segmentation and thickness measurements are correct. In such cases, the probability maps (also known as deviation maps) show abnormal (red and yellow) regions, which may mislead the clinician to assume disease is present. This is due to the anatomic variability of the individual, and the normative database must be taken into account. RESUMOA tomografia de coerência óptica é frequentemente usada para detectar glaucoma, bem como para monitorar a progressão. Este artigo analisa os tipos mais comuns de artefatos no relatório de tomografia de coerência óptica que podem ser confundidos com danos glaucomatosos. Nós nos concentramos principalmente nos artefatos relacionados à anatomia em que a segmentação da camada da retina e as medidas de espessura estão corretas. Nesses casos, os mapas de probabilidade (também conhecidos como mapas de desvio) mostram regiões anormais (vermelho e amarelo), o que pode induzir o clínico em erro ao supor que a doença está presente. Isto se deve à variabilidade anatômica do indivíduo, e o banco de dados normativo deve ser levado em conta.

Anatomical Features can Affect OCT Measures Used for Clinical Decisions and Clinical Trial Endpoints

“…1 C, red vertical lines), which have been associated with FPs. 12 , 16 – 26 Estimated axial length (Est-AL ) —Previous work has documented the influence of axial length on the OCT measures. 27 – 38 Measures of axial length were available for only 276 of the 396 RDB eyes.…”

Glaucoma Detection Using Optical Coherence Tomography: Reviewing the Pitfalls of Comparison to Normative Data

“…D, Simulation of cyclorotation (head tilt). Used with permission from Leshno et al 36 RNFL indicates retinal nerve fiber layer.…”

“…17 Note that the GCL probability map has an unrelated circum-foveal artifact discussed in the following sections. Used with permission from Leshno et al 36 cpRNFL indicates circumpapillary retinal nerve fiber layer; GCL, ganglion cell layer; RNFL, retinal nerve fiber layer; VF, visual field. Figure 5 can be viewed in color online at www.glaucomajournal.com.…”

“…B, A report of the same scan, after correcting the date of birth, shows a normal appearing RNFL and GCL without any significantly thin areas on the probability maps. Used with permission from Leshno et al36 APS, indicates Anatomic Positioning System; cpRNFL circumpapillary retinal nerve fiber layer; GCL, ganglion cell layer; MRW, minimum rim width; NAS, nasal; NI, nasal inferior; NS, nasal superior; OCT, optical coherence tomography; OS, oculus sinister; RNFL, retinal nerve fiber layer; RNFLT, retinal nerve fiber layer thickness; TI, temporal inferior; TMP, temporal; TS, Temporal superior. Figure7can be viewed in color online at www.glaucomajournal.com.…”

Prelaminar Neuronal Tissue Thickness May Be the Solution

“…The evidence-based literatures about bias of automated segmentations carry questions about accuracy and perfection of SD-OCT cpRNFLT in diagnosis and follow up of glaucoma and neurological disease. Large optic nerve, ONH drusen, parapillary optic atrophy, posterior vitreous detachment (PVD), tilted disc, congenital disc anomalies, epiretinal membrane, high myopia, bad centration all lead to failure of true automated segmentation [5][6][7][8][9][10]. Before making diagnostic decisions based on conventional printout of RNFL thickness, ophthalmologists should note if the patient has any abnormal ONH that may cause OCT artefacts and affect RNFL thickness interpretations.…”