Structural-Functional Correlation in Non-Arteritic Acute Ischemic Optic Neuropathy

Abstract

Purpose: This study investigated the relationships between structural and functional parameters in non-arteritic ischemic optic neuropathy (NAION).

Methods: This retrospective study enrolled 29 patients (58.2 ± 10.4 years old) with unilateral NAION. During the acute phase, we performed comprehensive evaluations including best-corrected visual acuity (BCVA), optical coherence tomography (OCT), optical coherence tomography angiography (OCTA), visual fields (VF), visual evoked potentials (VEP), electroretinography (ERG), and multifocal ERG (mf-ERG). At three months post-presentation, patients underwent follow-up assessments comprising visual acuity testing, perimetry, and advanced retinal imaging.

Results: During the acute phase, affected eyes demonstrated increased mean retinal nerve fiber layer (RNFL) thickness, while ganglion cell-inner plexiform layer (GCIPL) thickness decreased. Both visual fields mean deviation (MD) and VEP P100 amplitude were reduced, accompanied by prolonged peak latency. We also observed decreased P1 response density in mf-ERG. Analysis revealed significant direct correlations between GCIPL parameters and electrophysiological measurements, particularly VEP P100 amplitude and mf-ERG P1 response density. Mean GCIPL thickness, VF MD, and VEP P100 amplitude showed negative correlations with baseline logMAR VA. Baseline VF MD, VEP P100 amplitude, and minimum GCIPL thickness showed negative correlations with logMAR VA at 3-month follow-up.

Conclusion: Retinal ganglion cell layer thickness serves as a valuable indicator to objective evaluate optic nerve function in acute NAION patients. Decreases in both VEP amplitude and mf-ERG response density showed significant correlations with retinal ganglion cell layer thickness. Baseline visual field performance, VEP measurements, and minimum GCIPL thickness exhibited negative correlations visual acuity at 3-month follow-up.

Trial registration: Clinical Research Ethics Committee of Xi'an People's Hospital (NO. 20220018). Registered 27 September 2022-Retrospectively registered, https://www.medicalresearch.org.cn/. Informed consent was obtained from each participant.

Keywords: OCT; OCTA; ischemic optic neuropathy; visual electrophysiology; visual field.

Figure 1

OCT-A measurement of the radial peripapillary capillaries (RPC, Figure 1A) and macular superficial capillary plexus (mSCP, Figure 1B). The scanned area was 6×6 mm², and the areas in the range of 1 mm, 1–3 mm, and 3–6 mm scanned diameter centered on the optic nerve head (ONH) or central macula were defined as the center-RPC or center mSCP, inner-RPC or inner-mSCP and outer-RPC or outer-mSCP, respectively.

Figure 2

(A) The difference of the retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) between the NAION eyes (NE) and the fellow eyes (FE). In acute phase, the mean RNFL thickness of NE was significantly thicker than FE and the mean GCIPL thickness was thinner in NE compared to FE. (B) Differences in GCIPL thickness between NE and FE at different timepoint of onset in the acute phase (Group (A) <1 week, Group (B) 1–2 weeks, Group (C) 2–4 weeks). Solid columns represent NE, hollow columns represent FE, and error lines represent standard deviation (SD). The thinning of mean GCIPL thickness in NE was after 7 days of onset. The results of the paired t-tests are shown: *P < 0.05, **P < 0.01, ***P < 0.001.

Figure 3

The difference of the minimum ganglion cell-inner plexiform layer (GCIPL) thickness between the NAION eyes (NE) and the fellow eyes (FE) in acute phase and at different timepoint of onset in the acute phase (Group (A) <1 week, Group (B) 1–2 weeks, Group (C) 2–4 weeks). In acute phase, the minimum GCIPL thickness was thinner in NE compared to FE. The thinning of minimum GCIPL thickness in NE was after 7 days of onset. Solid columns represent NE, hollow columns represent FE, and error lines represent standard deviation (SD). The results of the paired t-tests are shown: *P < 0.05, **P < 0.01.

Figure 4

Differences in vessel density (VD) between the NAION eyes (NE) and the fellow eyes (FE) in the superficial capillary layer in the optic disc (A) and macula (B). Solid columns represent NE, hollow columns represent FE, and error lines represent standard deviation (SD). Only the center-peripapillary capillaries (RPC) of VD was thickening in NE. The results of the paired t-tests are shown: *P < 0.05.

Figure 5

The differences of mean deviation (MD) of the visual field (A), amplitude and peak time of pattern visual evoked potentials (PVEP) P100 (B), and the P1 response density of multifocal electroretinography (mf-ERG) (C) between the NAION eyes (NE) and the fellow eyes (FE). The P1 response density decreased in Group B (1–2 weeks) and Group C (2 weeks – 1 month) in NE when compared to FE (D). Solid columns represent NE, hollow columns represent FE, and error bars represent standard deviation (SD). In NE, the mean deviation (MD) of the visual field, P100 amplitude and the P1 response density of mf-ERG reduced significantly. The peak timing of P100 wave prolonged. The results of the paired t-tests are shown: *P < 0.05, **P < 0.01, ***P < 0.001.

Figure 6

The correlation between mean ganglion cell-inner plexiform layer (GCIPL) thickness and the amplitude of P100 wave of pattern visual evoked potentials (PVEP) (A) and the P1 response density of multifocal electroretinography (mf-ERG) (B) in NAION eyes (NE). X-axis represents mean GCIPL thickness of NE, and Y-axis represents P100 amplitude and the P1 response density of mf-ERG. Positive correlations were revealed between GCIPL thickness and P100 amplitude or the P1 response density of mf-ERG. The results of the Spearman correlation test are shown in the figure: *P < 0.05.

Figure 7

Correlation of logMAR visual acuity of the NAION eyes (NE) with mean ganglion cell-inner plexiform layer (GCIPL) thickness (A), the mean deviation (MD) of the visual field (B), and the amplitude of pattern visual evoked potentials (PVEP) P100 (C). X-axis represents the logMAR visual acuity of NE, and Y-axis represents the mean GCIPL thickness, MD of the visual field, and amplitude of PVEP P100. Each symbol represents each patient, and the gray line represents the best linear fit. GCIPL thickness, MD of the visual field, and P100 amplitude were all significantly negatively correlated with visual acuity. The results of Spearman correlation test are shown in the figure: *P < 0.05, ***P < 0.001.

Figure 8

Changes in the mean retinal nerve fiber layer (RNFL) thickness (A), mean ganglion cell-inner plexiform layer (GCIPL) thickness (B), and minimum GCIPL thickness (C) after 3 months in patients with NAION. Solid grey columns represent the NAION eyes (NE) at baseline, hollow columns represent the fellow eyes (FE), blue represents after 3 months of treatment, and error lines represent standard deviation (SD). The results of the paired t-test are shown in the figure: *P < 0.05, **P < 0.01.

Figure 9

Changes in optic disc vessel density of the NAION eyes (NE) in the superficial capillary layer after 3 months and the differences with the fellow eyes (FE) in patients with NAION. Gray columns represent NE at baseline, blue columns represent after 3 months of treatment, and error lines represent standard deviation (SD). The results of the paired t-test are shown in the figure: *P < 0.01, **P < 0.05, ***P < 0.001.

Figure 10

Correlation of logMAR visual acuity of the NAION eyes (NE) at 3 months with its the mean deviation (MD) of the visual field (VF) (A), amplitude of pattern visual evoked potentials (PVEP) P100 (B), and the minimum ganglion cell-inner plexiform layer (GCIPL) thickness (C) at baseline. X-axis represents the logMAR visual acuity of NE, and Y-axis represents the MD of the VF, amplitude of VEP P100 and minimum GCIPL thickness. Each symbol represents each patient, and the gray line represents the best linear fit. MD on VF, P100 amplitude, and the minimum GCIPL thickness of NE at baseline displayed a negative correlation with logMAR visual acuity at 3 months. The results of Spearman correlation test are shown in the figure: *P < 0.05.