Evaluation of Retinal Layer Thicknesses in Patients with Keratoconus Using Retinal Layer Segmentation Analysis

Abstract

Objective To conduct an evaluation of the effects of irregular astigmatism on the retinal nerve fiber layer (RNFL) and the retinal layers observed using spectral-domain optical coherence tomography (SD-OCT) in patients who had keratoconus (KC).

Materials and Methods A total of 255 eyes from 255 individuals, comprising 72 eyes of KC patients, 70 eyes of patients with astigmia, and 113 eyes of healthy controls were included in the analysis. RNFL scan maps (comprising global, temporal, superotemporal, inferotemporal, nasal, inferonasal, and superonasal maps) and macular thickness (MT) maps of a standard from the Early Treatment Diabetic Retinopathy Study (ETDRS) grid were assessed. The measurements were segmented automatically using Spectralis software, and included the RNFL, inner and outer plexiform layers (IPL, OPL), inner and outer nuclear layers (INL, ONL), ganglion cell layer, retinal pigment epithelium (RPE) in the central 6-mm ETDRS subfield.

Results The RNFL thickness in the KC group was lower when compared with the other two groups; however, statistically significant differences were noted in the global, temporal, superotemporal, and inferotemporal sectors (p < 0.05 for all). All of the central MT parameters showed significant variation among the groups, while a statistically significant decrease was noted in the KC group, except in the inferior outer sector (p = 0.741). In the segmentation analysis, the KC group had the significantly lowest IPL, ONL, RPE, and outer retinal layer (ORL) thickness among the groups (p < 0.05 for each). The astigmatic group was similar to the control group with regard to these parameters (p > 0.05 for each).

Conclusion The eyes in the KC group appeared to have a thinner RNFL and MT when compared to those in the astigmatic and control groups. The ORLs, especially the ONL and RPE, were the most affected component of the macula in the KC group.

Zusammenfassung

Hintergrund Es sollte eine Bewertung der Auswirkungen von irregulärem Astigmatismus auf die retinale Nervenfaserschicht (RNFL) und die Netzhautschichten durchgeführt werden, die bei Patienten mit Keratokonus (KC) mittels optischer Kohärenztomografie (SD-OCT) im Spektralbereich beobachtet wurden.

Methoden Insgesamt 255 Augen von 255 Personen, davon 72 Augen von KC-Patienten, 70 Augen von Patienten mit Astigmatismus und 113 Augen von gesunden Kontrollpersonen, wurden in die Analyse eingeschlossen. RNFL-Scankarten (umfassend globale, temporale, superotemporale, inferotemporale, nasale, inferonasale und superonasale) und Makuladickekarten (MT-Karten) eines Standardrasters der Early Treatment Diabetic Retinopathie Study (ETDRS) wurden bewertet. Die Messungen wurden automatisch mit der Spectralis-Software segmentiert und umfassten die RNFL, innere und äußere plexiforme Schicht (IPL, OPL), innere und äußere Kernschicht (INL, ONL), Ganglienzellschicht, retinales Pigmentepithel (RPE) im zentralen 6-mm-ETDRS-Unterfeld.

Ergebnisse Die RNFL-Dicke in der KC-Gruppe war im Vergleich zu den anderen beiden Gruppen geringer; jedoch wurden statistisch signifikante Unterschiede in den globalen, temporalen, superotemporalen und inferotemporalen Sektoren festgestellt (p < 0,05 für alle). Alle zentralen MT-Parameter zeigten eine signifikante Variation zwischen den Gruppen, während eine statistisch signifikante Abnahme in der KC-Gruppe festgestellt wurde, außer im unteren äußeren Sektor (p = 0,741). In der Segmentierungsanalyse wies die KC-Gruppe die signifikant niedrigste IPL, ONL, RPE-Schicht und die signifikant niedrigste Dicke der äußeren Netzhautschicht (ORL) unter den Gruppen auf (jeweils p < 0,05). Die astigmatische Gruppe war hinsichtlich dieser Parameter der Kontrollgruppe ähnlich (jeweils p > 0,05).

Schlussfolgerungen Diejenigen in der KC-Gruppe schienen im Vergleich zu denen in der Astigmatismus- und Kontrollgruppe eine dünnere RNFL und MT zu haben. Die ORLs, insbesondere ONL und RPE, waren die am stärksten beeinflusste Komponente der Makula in der KC-Gruppe.

Key words

Keratoconus - optical coherence tomography - retinal layer thickness - retinal nerve fiber layer

Schlüsselwörter

Keratokonus - optische Kohärenztomografie - Netzhautschichtdicke - Netzhautnervenfaserschicht

Publication History

Received: 01 October 2021

Accepted: 16 January 2022

Article published online:
23 March 2022

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