Peripapillary and parafoveal microvascular changes in eyes with optic neuritis and their fellow eyes measured by optical coherence tomography angiography: an Exploratory Study

Parapapillary choroidal microvasculature in retrobulbar optic neuritis: An optical coherence tomography angiography study

PURPOSE

To compare superficial and deep vascular characteristics of the optic disc in retrobulbar optic neuritis using optical coherence tomography angiography (OCT-A).

METHODS

Nineteen patients with unilateral non-infectious retrobulbar neuritis were included in the study. The contralateral eyes of each patient were served as controls. OCT-A scans of the optic discs were performed in a 4.5 × 4.5 mm rectangular area, while macular OCT-A scans were performed in a 6 × 6 mm rectangular area. Various parameters, including radial peripapillary capillary (RPC) density, peripapillary retinal nerve fibre layer (pRNFL) thickness, cup volume, rim area, disc area, cup-to-disc (c/d) area ratio, and vertical and horizontal c/d ratios were automatically obtained using the instrument software. The density for superficial capillary plexus (SCP) and deep capillary plexus (DCP) were assessed using macular OCT-A. Parapapillary choroidal microvascular (PPCMv) density was calculated using MATLAB software.

RESULTS

Parafoveal inferior, perifoveal total and inferior SCP densities were significantly decreased in eyes with optic neuritis when compared with contralateral control eyes in OCT-A measurements (respectively, p = 0.027, p = 0.041, p = 0.045). The axial lengths, (p = 0.72), vertical and horizontal cup-disc ratios, and disc area, cup-disc areas, cup volumes, and pRNFL thicknesses between the groups were similar (for each, p>0.05).

CONCLUSIONS

This study demonstrated for the first time that patients with retrobulbar optic neuritis had decreased SCP densities, though it did not cause any changes in PPCMv density.

Retinal Vascular Density Using Optical Coherence Tomography-Angiography in Optic Neuritis

The aim of this study is to access the perifoveolar and peripapillary vascular density (VD) using optical coherence tomography-angiography (OCT-A) in eyes with optic neuritis (ON) and in fellow eyes, then compare that to healthy controls.

METHOD

This is a cross-sectional study including 22 patients with unilateral ON and 20 control eyes of healthy subjects. A complete clinical examination and OCT-A were performed at least 6 months after the acute episode of optic neuritis. Vascular plexuses of the peripapillary and perifoveolar images obtained from OCT-A were used to calculate the VD in each plexus: superficial, deep, and peripapillary capillaries for each group (ON eyes, fellow eyes, healthy eyes).

RESULTS

Compared to healthy control eyes, in the peripapillary area, we found a significant decrease in VD not only in ON eyes but also in fellow eyes in average (p ≤ 0.05) and in the temporal sector (p < 0.001). In the perifoveolar area, the VD of the superficial capillary plexus is decreased in all sectors (p < 0.001) in ON eyes and only in the upper sector (p = 0.037) of fellow eyes compared to control eyes. VD correlates with ganglion cell layer (GCL) thickness in ON and in fellow eyes.

CONCLUSION

Peripapillary vascular density is decreased in both affected eyes and fellow eyes after a unilateral episode of optic neuritis, suggesting a subclinical involvement of the disease. Further studies are needed to clarify the mechanism and clinical implications of these data.

Peripapillary and macular microvasculature features of non-arteritic anterior ischemic optic neuropathy

Purpose

The hallmark of non-arteritic anterior ischemic optic neuropathy (NAION) is vascular compromise to the anterior optic nerve and thinning of the retinal nerve fiber layer (RNFL) and secondary degeneration of the retinal ganglion cell body or thinning of the ganglion cell complex (GCC). This study investigates optical coherence tomography (OCT) and OCT Angiography (OCTA) changes in chronic NAION and identifies imaging biomarkers that best predict disease.

Methods

We performed a retrospective case-control study of 24 chronic NAION eyes (18 patients) and 70 control eyes (45 patients) to compare both whole-eye and regional OCT, OCTA, static perimetry measurements. OCT measurements were quantified automatically using commercial software, and OCTA was analyzed using custom MATLAB script with large vessel removal to measure 154 total parameters per eye.

Results

We confirmed that static perimetry mean deviation (MD) was significantly worse in chronic NAION (-13.53 ± 2.36) than control (-0.47 ± 0.72; P < 0.001) eyes, and NAION eyes had 31 μm thinner RNFL (control: 95.9 ± 25.8 μm; NAION: 64.5 ± 18.0, P < 0.001), and 21.8 μm thinner GCC compared with controls (control: 81.5 ± 4.4 μm; NAION: 59.7 ± 10.5, P < 0.001). Spearman correlation analysis of OCTA parameters reveal that vessel area density (VAD) and flux are highly correlated with visual field MD and OCT measurements. Hierarchical clustering two distinct groups (NAION and control), where standardized measurements of NAION eyes were generally lower than controls. Two-way mixed ANOVAs showed significant interaction between patient status (control and chronic NAION) and structure (optic disk and macula) for annulus VAD and flux values and mean RNFL and GCC thickness. Post-hoc tests showed this effect stems from lower peripapillary values in NAION compared to controls. Separate logistic regression models with LASSO regularization identified VAD and flux are one of the best OCTA parameters for predicting NAION.

Conclusion

Ischemic insult to the optic disk is more severe likely from primary degeneration of the affected peripapillary region while macula is affected by secondary retrograde degeneration and loss of retinal ganglion cells. In addition to OCT measurements, peripapillary and macular vascular parameters such as VAD and flux are good predictors of optic nerve and retinal changes in NAION.

The Role of Optical Coherence Tomography Angiography in Optic Nerve Head Edema: A Narrative Review

Optic nerve head (ONH) edema is a clinical manifestation of many ocular and systemic disorders. Ocular and central nervous system imaging has been used to differentiate the underlying cause of ONH edema and monitor the disease course. ONH vessel abnormalities are among the earliest signs of impaired axonal transportation. Optical coherence tomography angiography (OCTA) is a noninvasive method for imaging ONH and peripapillary vessels and has been used extensively for studying vascular changes in ONH disorders, including ONH edema. In this narrative review, we describe OCTA findings of the most common causes of ONH edema and its differential diagnoses including ONH drusen.

Peripapillary structural and microvascular alterations in early dysthyroid optic neuropathy

Background

To explore the changes in blood supply and structure around the optic nerve head (ONH) in thyroid-associated ophthalmopathy (TAO) patients with suspected dysthyroid optic neuropathy (DON).

Methods

TAO patients [19 with DON; 24 non-DON (NDON); 20 with equivocal DON (EDON)], and 34 control subjects were examined. Optical coherence tomography angiography (OCTA) was used to obtain peripapillary retinal nerve fiber layer (p-RNFL) and vessel density parameters, including the ONH whole image vessel density (ONH-wiVD) and the radial peripapillary capillary vessel density (RPC-VD) in early DON.

Results

Although there were no differences in p-RNFL thickness among the groups, there were differences in the ONH-wiVD of each grid section and the RPC-VD in all areas (P < 0.01). Compared with healthy controls, the EDON eyes had significantly lower RPC-VDs in all aeras (P < 0.05).The peripapillary region was further divided into eight sectors, and the RPC-VD in the temporal upper, superior temporal, and temporal lower sectors in the EDON group were significantly lower than in the controls. The visual impairment was closely related to the loss of peripapillary capillary vessel density. Univariate correlation analysis showed that the ONH-wiVD and RPC-VD of the TAO groups were negatively correlated with the intraocular pressure (r = − 0.296, P = 0.006; r = − 0.258, P = 0.016 respectively).

Conclusions

EDON patients had significantly lower ONH-wiVD and RPC-VD than control subjects, and the temporal and upper VDs were more likely to be affected in the early stage of TAO. The combined use of spectral domain optical coherence tomography and OCTA technologies offer a new method for early diagnosis of suspected DON patients.

Microvascular changes in the macular and parafoveal areas of multiple sclerosis patients without optic neuritis

Retinal imaging has been proposed as a biomarker for neurological diseases such as multiple sclerosis (MS). Recently, a technique for non-invasive assessment of the retinal microvasculature called optical coherence tomography angiography (OCTA) was introduced. We investigated retinal microvasculature alterations in participants with relapsing–remitting MS (RRMS) without history of optic neuritis (ON) and compared them to a healthy control group. The study was performed in a prospective, case–control design, including 58 participants (n = 100 eyes) with RRMS without ON and 78 age- and sex-matched control participants (n = 136 eyes). OCTA images of the superficial capillary plexus (SCP), deep capillary plexus (DCP) and choriocapillaris (CC) were obtained using a commercial OCTA system (Zeiss Cirrus HD-5000 Spectral-Domain OCT with AngioPlex OCTA, Carl Zeiss Meditec, Dublin, CA). The outcome variables were perfusion density (PD) and foveal avascular zone (FAZ) features (area and circularity) in both the SCP and DCP, and flow deficit in the CC. MS group had on average higher intraocular pressure (IOP) than controls (P < 0.001). After adjusting for confounders, MS participants showed significantly increased PD in SCP (P = 0.003) and decreased PD in DCP (P < 0.001) as compared to controls. A significant difference was still noted when large vessels (LV) in the SCP were removed from the PD calculation (P = 0.004). Deep FAZ was significantly larger (P = 0.005) and less circular (P < 0.001) in the eyes of MS participants compared to the control ones. Neither LV, PD or FAZ features in the SCP, nor flow deficits in the CC showed any statistically significant differences between the MS group and control group (P > 0.186). Our study indicates that there are microvascular changes in the macular parafoveal retina of RRMS patients without ON, showing increased PD in SCP and decreased PD in DCP. Further studies with a larger cohort of MS patients and MRI correlations are necessary to validate retinal microvascular changes as imaging biomarkers for diagnosis and screening of MS.

Microvasculature Features of Vogt-Koyanagi-Harada Disease Revealed by Widefield Swept-Source Optical Coherence Tomography Angiography

Background: Vogt-Koyanagi-Harada (VKH) disease is a multisystem autoimmune disorder which could induce bilateral panuveitis involving the posterior pole and peripheral fundus. Optical coherence tomography angiography (OCTA) provides several advantages over traditional fluorescence angiography for revealing pathological abnormalities of the retinal vasculature. Until recently, however, the OCTA field of view (FOV) was limited to 6 × 6 mm² scans.

Purpose: This study examined retinal vasculature and choriocapillaris abnormalities across multiple regions of the retina (15 × 9 mm² wide field, macular, peripapillary regions) among acute and convalescent VKH patients using a novel widefield swept-source OCTA (WSS-OCTA) device and assessed correlations between imaging features and best-corrected visual acuity (BCVA).

Methods: Twenty eyes of 13 VHK disease patients in the acute phase, 30 eyes of 17 patients in the convalescent phase, and 30 eyes of 15 healthy controls (HCs) were included in this study. Vascular length density (VLD) in superficial and deep vascular plexuses (SVP, DVP), vascular perfusion density (VPD) in SVP, DVP, and choriocapillaris (CC), and flow voids (FV) in CC were measured across multiple retinal regions via WSS-OCTA (PLEX Elite 9000, Carl Zeiss Meditec Inc., USA) using the 15 × 9 mm² scan pattern centered on the fovea and quantified by ImageJ.

Results: Compared to HCs, acute phase VKH patients exhibited significantly reduced SVP-VLD, SVP-VPD, and CC-VPD across multiple retinal regions (all p < 0.01). Notably, the FV area was more extensive in VKH patients, especially those in the acute phase (p < 0.01). These changes were reversed in the convalescent phase. Stepwise multiple linear regression analysis demonstrated that macular DVP-VLD and macular CC-VPD were the best predictive factors for BCVA in the acute and convalescent VKH groups.

Conclusion: The wider field of SS-OCAT provides more comprehensive and detailed images of the microvasculature abnormalities characterizing VKH disease. The quantifiable and layer-specific information from OCTA allows for the identification of sensitive and specific imaging markers for prognosis and treatment guidance, highlighting WSS-OCTA as a promising modality for the clinical management of VKH disease.