Quantitative OCT Angiography Evaluation of Peripapillary Retinal Circulation after Plaque Brachytherapy

Prospective assessment of peripapillary microvasculature using optical coherence tomography angiography in para-optic intracranial and sinonasal tumors treated with proton therapy

PURPOSE

Radiation-induced optic neuropathy (RION) is rare but may lead to blindness. The mechanisms by which this occurs include endothelial and neuronal damage, but RION has been assessed very little in the case of extraocular tumors treated with high-energy proton therapy, the use of which is expanding worldwide. We assessed peripapillary microvascular changes by optical coherence tomography angiography (OCT-A) in patients undergoing high-energy proton therapy for para-optic intracranial or head and neck tumors.

MATERIALS AND METHODS

In this prospective institutional review board approved study, patients receiving>40Gy_RBE maximal PBT dose to their optic nerve between 2018 and 2020 underwent quantitative OCT-A analyses. ImageJ software was used to assess changes in the peripapillary superficial vascular complex (SVC) using vascular area density (VAD), vessel length density (VLD) and fractal dimension (FDsk). Uni- and multivariate analyses were performed.

RESULTS

Of 47 patients (78 eyes) with 29±6 months of follow-up (range 18-42), 29 patients (61.7%) had previously undergone surgery and 18 (32.1%) had microvascular abnormalities prior to proton therapy. Total radiotherapy dose was the most relevant factor in decreased peripapillary microvasculature. Duration of follow-up was associated with lower VAD (P=0.005) and mean retinal nerve fiber layer (RNFLm) thickness also decreased. There was no significant correlation between OCT-A changes and mean visual defect.

CONCLUSION

Peripapillary microvasculature changes may occur from tumor compression or surgery and proton therapy for extraocular tumors. OCT-A may provide quantitative and mechanistic insights into RION before the occurrence of clinical symptoms.

Early anti-VEGF treatment for radiation maculopathy and optic neuropathy: lessons learned

Radiation therapy has saved both sight and life for eye cancer patients. The most common methods include ophthalmic plaque brachytherapy and external beam techniques. However, subsequent dose-dependent radiation vasculopathy invariably occurs within and around the targeted zone. In 2006, Finger discovered that periodic intravitreal anti-vascular endothelial growth factor (anti-VEGF) bevacizumab could reverse and suppress intraocular radiation vasculopathy. At first, it was administered at the onset of radiation-related vision loss. Though bevacizumab induced regression of macular oedema, retinal haemorrhages and cotton-wool infarcts, most patients were left with residual retinal damage, manifest as metamorphopsia and loss of vision. These results led to earlier and earlier anti-VEGF interventions: first after signs of progressive radiation retinopathy, and then for signs of radiation maculopathy, and finally for high-risk eyes with no clinical signs of retinopathy. Earlier initiation of intravitreal anti-VEGF therapy typically resulted in greater restoration and preservation of macular anatomy, reductions of retinal haemorrhages, resolution of cotton-wool spots and vision preservation. Recent research on optical coherence tomography angiography (OCT-A) has revealed that radiation vasculopathy occurs prior to clinical ophthalmic signs or symptoms. Therefore, it seemed reasonable to consider treating high-risk patients (considered certain to eventually develop radiation maculopathy) to prevent or delay vision loss. Herein, we describe the evolution of treatment for radiation maculopathy as well as recent research supporting anti-VEGF treatment of high-risk patients immediately following radiation to maximize vision outcomes.

Imaging of Uveal Melanoma—Current Standard and Methods in Development

Simple Summary

Uveal melanoma is the most prevalent intraocular tumor in adults, derived from melanocytes; the liver is the most common site of its metastases. Due to troublesome tumor localization, different imaging techniques are utilized in diagnostics, i.e., fundus imaging (FI), ultrasonography (US), optical coherence tomography (OCT), single-photon emission computed tomography (SPECT), positron emission tomography/computed tomography (PET/CT), magnetic resonance imaging (MRI), fundus fluorescein angiography (FFA), indocyanine green angiography (ICGA), or fundus autofluorescence (FAF). Specialists eagerly use these techniques, but sometimes the precision and quality of the obtained images are imperfect, raising diagnostic doubts and prompting the search for new ones. In addition to analyzing the currently utilized methods, this review also introduces experimental techniques that may be adapted to clinical practice in the future. Moreover, we raise the topic and present a perspective for personalized medicine in uveal melanoma treatment.

Abstract

Uveal melanoma is the most common primary intraocular malignancy in adults, characterized by an insidious onset and poor prognosis strongly associated with tumor size and the presence of distant metastases, most commonly in the liver. Contrary to most tumor identification, a biopsy followed by a pathological exam is used only in certain cases. Therefore, an early and noninvasive diagnosis is essential to enhance patients’ chances for early treatment. We reviewed imaging modalities currently used in the diagnostics of uveal melanoma, including fundus imaging, ultrasonography (US), optical coherence tomography (OCT), single-photon emission computed tomography (SPECT), fundus fluorescein angiography (FFA), indocyanine green angiography (ICGA), fundus autofluorescence (FAF), as well as positron emission tomography/computed tomography (PET/CT) or magnetic resonance imaging (MRI). The principle of imaging techniques is briefly explained, along with their role in the diagnostic process and a summary of their advantages and limitations. Further, the experimental data and the advancements in imaging modalities are explained. We describe UM imaging innovations, show their current usage and development, and explain the possibilities of utilizing such modalities to diagnose uveal melanoma in the future.

Postradiation Optic Atrophy Is Associated With Intraocular Pressure and May Manifest With Neuroretinal Rim Thinning

BACKGROUND

To determine risk factors for postradiation optic atrophy (PROA) after plaque radiotherapy for uveal melanoma.

METHODS

A single center, retrospective cohort study of patients diagnosed with uveal melanoma involving choroid and/or ciliary body treated with plaque between January 1, 2008, and December 31, 2016. Outcomes included development of PROA with pallor alone or with concomitant neuroretinal rim thinning (NRT). Cox regression analysis was performed to identify risk factors for PROA.

RESULTS

Of 78 plaque-irradiated patients, PROA developed in 41 (53%), with concomitant NRT in 15 (19%). Risk factors for PROA of any type included presentation with worse visual acuity (odds ratio [95% confidence interval] 5.6 [2.3-14.1], P < 0.001), higher baseline intraocular pressure (IOP; 14 vs 16 mm Hg) (1.1 [1.0-1.2], P = 0.03), shorter tumor distance to optic disc (1.3 [1.2-1.5], P < 0.001) and foveola (1.2 [1.1-1.3], P < 0.001), subfoveal subretinal fluid (3.8 [2.0-7.1], P < 0.001), greater radiation prescription depth (1.3 [1.1-1.6], P = 0.002), dose to fovea (point dose) (1.01 [1.01-1.02], P < 0.001), and mean (1.02 [1.02-1.03], P < 0.001) and maximum dose to optic disc per 1 Gy increase (1.02 [1.01-1.03], P < 0.001). On multivariate modeling, dose to disc, baseline IOP, and subfoveal fluid remained significant. Subanalysis revealed risk factors for pallor with NRT of greater mean radiation dose to disc (1.03 [1.01-1.05], P = 0.003), higher maximum IOP (17 vs 20 mm Hg) (1.4 [1.2-1.7], P < 0.001), and subfoveal fluid (12 [2-63], P = 0.004).

CONCLUSION

PROA may result in NRT in addition to optic disc pallor. Risk factors for PROA included higher radiation dose to optic disc, higher baseline IOP, and subfoveal fluid. Higher maximum IOP contributed to concomitant NRT.

Optic disc cupping after circumpapillary Pd-103 slotted plaque radiation therapy

OBJECTIVE

To investigate vascular and morphologic optic disc changes after slotted plaque radiation therapy for choroidal melanoma involving the optic disc.

DESIGN

Retrospective cross-sectional study.

PARTICIPANTS

Thirty-nine patients with choroidal melanoma involving the optic nerve.

METHODS

Each melanoma was treated with palladium-103 slotted plaque brachytherapy (incorporating and/or surrounding the optic nerve sheath) between 2005 and 2019. Imaging of the optic nerve before and after radiation allowed for documentation and evaluation of optic nerve pallor and cup-to-disc ratio (CDR) changes. Optical coherence tomography (OCT) CDR measurements and intraocular pressure (IOP) were recorded pretreatment and at follow-up. Of these patients, 22 also had OCT angiography (OCT-A) images with sufficient quality for evaluation of blood vessel density and length. Differences in cup-to-disc measurements were correlated with changes in OCT-A-measured vessel density and length.

RESULTS

Following slotted plaque radiation therapy, there was no significant increase in IOP or optic nerve pallor. OCT and colour photography revealed significant increases (both p < 0.001) in CDR from pretreatment to the last follow-up. Increased CDRs on OCT were significantly correlated to OCT-A-measured change in vessel length (p = 0.027). Similarly, increased CDR ratios on fundus photography were significantly correlated with OCT-A-measured change in vessel density (p = 0.043) and length (p = 0.019).

CONCLUSION

Fundus photography and OCT measurements revealed increased optic disc cupping following slotted plaque radiation therapy. Cupping was associated with OCT-A evidence of synchronous progressive peripapillary vascular occlusion and attenuation. Therefore, slotted plaque radiation-induced peripapillary and papillary ischemia was associated with increased CDR ratios and optic disc cupping.

RETINAL MICROVASCULAR CHANGES IN UVEAL MELANOMA FOLLOWING CONBERCEPT INJECTION AFTER PLAQUE RADIOTHERAPY AS DETECTED BY OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

PURPOSE

To investigate macular microvascular characteristics imaged by optical coherence tomography angiography in patients with uveal melanoma following conbercept injections after plaque radiotherapy.

METHODS

Prospective comparative analysis comprising 15 patients with uveal melanoma with conbercept injections and 30 patients without conbercept injections after plaque radiotherapy by optical coherence tomography angiography. The conbercept group received intravitreal conbercept injections at the time of plaque removal, 1 month, 3 months, 6 months , 9 months and 12 months after plaque removal (total, 6 injections). The control group had no intravitreal conbercept injection.

RESULTS

After initiation of conbercept injections, superficial retinal vascular density in the whole image and parafoveal region were significantly higher at 6 months, whereas there was no significant difference at 9 months and 12 months. In analysis of variance analysis, superficial retinal vascular density in the whole image remained stable after conbercept injections (P = 0.069), whereas the superficial retinal vascular density decreased significantly after plaque radiotherapy in the control group (P = 0.011). In multivariable linear regression, a higher superficial retinal vascular density in the whole image region at 6 months was significantly associated with intravitreal conbercept injection (P = 0.018), wider tumor base (P = 0.026), and thinner tumor thickness (P = 0.04).

CONCLUSION

Optical coherence tomography angiography can provide a quantitative evaluation of early retinal microvascular changes after radiotherapy. Intravitreal conbercept treatment could partly relieve the retinal vascular damage in response to radiation therapy at early stage in patients with uveal melanoma; however, it may not be able to provide long-term positive functional outcomes.

Evaluation of radiation maculopathy after treatment of choroidal melanoma with ruthenium-106 using optical coherence tomography angiography

BACKGROUND

To assess the impact of brachytherapy on macular microvasculature utilizing optical coherence tomography angiography (OCTA) in treated choroidal melanoma.

METHODS

In this retrospective observational case series, we reviewed the recorded data of the patients with unilateral extramacular choroidal melanoma treated with ruthenium - 106 (¹⁰⁶Ru) plaque radiotherapy with a follow-up period of more than 6 months. Automatically measured OCTA retinal parameters were analysed after image processing.

RESULTS

Thirty-one eyes of 31 patients with the mean age of 51.1 years were recruited. Six eyes had no radiation maculopathy (RM). From 25 eyes with RM, nine eyes (36%) revealed a burnout macular microvasculature with imperceptible vascular details. Twenty-one non-irradiated fellow eyes from the enrolled patients were considered as the control group. Foveal and optic disc radiation dose had the highest value to predict the burnout pattern (ROC, AUC: 0.763, 0.727). Superficial and deep foveal avascular zone (FAZ) were larger in irradiated eyes in comparison to non-irradiated fellow eyes (1629 μm² vs. 428 μm², P = 0.005; 1837 μm² vs 268 μm², P = 0.021; respectively). Foveal and parafoveal vascular area density (VAD) and vascular skeleton density (VSD) in both superficial and deep capillary plexus (SCP and DCP) were decreased in all irradiated eyes in comparison with non-irradiated fellow eyes (P < 0.001). Compared with non-irradiated fellow eyes, irradiated eyes without RM had significantly lower VAD and VSD at foveal and parafoveal DCP (all P < 0.02). However, these differences at SCP were not statistically significant.

CONCLUSION

The OCTA is a valuable tool for evaluating RM. Initial subclinical microvascular insult after ¹⁰⁶Ru brachytherapy is more likely to occur in DCP. The deep FAZ area was identified as a more critical biomarker of BCVA than superficial FAZ in these patients.

Radiation Retinopathy: Detection and Management Strategies

A gradual shift in trend from primary enucleation to globe salvaging radiation therapy for the management of ocular tumors has resulted in the rise of several post-treatment ocular complications including radiation retinopathy. Radiation retinopathy is a chronic, progressive, and occlusive vasculopathy that can manifest anytime between 1 month to 15 years after starting radiation therapy. The aim of treatment in most of these cases is to prevent further vision loss. Treatment options such as laser photocoagulation, anti-vascular endothelial growth factor and intraviral steroids have been described. However, despite several advances in diagnostic and therapeutic modalities, a significant proportion of eyes with radiation retinopathy eventually go blind. This review summarises some of the clinical features, investigative modalities, and recent therapeutic strategies used in the management of radiation retinopathy.

OCT-A evaluation of radiation vasculopathy following slotted plaque brachytherapy

PURPOSE

To determine a reliable diagnostic method to reveal and monitor subclinical progression of neural and perineural radiation vasculopathy.

METHODS

A retrospective cross-sectional study, where optical coherence tomography angiography (OCT-A) imaging data was collected and analyzed from 22 consecutive patients that had been treated with circumneural slotted plaque brachytherapy for peripapillary, juxtapapillary, or circumpapillary choroidal melanomas. Pre-operative dosimetry of palladium-103 radiation dose to the optic nerve and fovea were collected. Quantified differences in OCT-A-measured vessel density and length in treated verses untreated contralateral control eyes were collected. Vessel density and length were correlated to radiation dose, plaque slot depth, visual acuity outcomes, and circumpapillary retinal nerve fiber layer thickness.

RESULTS

Patients had post-irradiation follow-up of median 39 months, interquartile range 62 months). The mean optic disc radiation dose was 89.9 Gy ± 39.2 (86.5, 30.8-189.0). In comparison to controls, OCT-A imaging revealed significant differences in radial peripapillary capillary vessel density (18 μm² in case eyes, 34 μm² in control eyes; p < 0.001) and length (10 μm in case eyes, 14 μm in control eyes; p < 0.001). Change in vessel density did not show a significant correlation to radiation dose, slot depth, or visual acuity. However, change in vessel length was significantly correlated to radiation dose (p = 0.049) and change in visual acuity (p < 0.001).

CONCLUSIONS

OCT-A imaging revealed that radial peripapillary capillary vessel density and length were significantly reduced after circumneural irradiation for choroidal melanoma. Therefore, OCT-A imaging can be used to monitor progression of papillary vasculopathy associated with radiation optic neuropathy.

Recent advances in wide field and ultrawide field optical coherence tomography angiography in retinochoroidal pathologies

Introduction: With the advent of wide field (WF) and ultra-wide field (UWF) imaging in color fundus photography and fluorescein angiography (FA), the importance of an expanded field-of-view (FOV) has been illustrated for early detection of several chorioretinal disorders. The need to bring similar utility to optical coherence tomography angiography (OCTA) is imperative.Areas covered: For this review, we explored all research items with WF or UWF on Pubmed Central and Google Scholar. Software-based methods included algorithms for motion correction, artifact reduction, image pre-processing, post-processing and montage protocols while hardware methods included swept-source OCTA, faster scanning sources, hardware-based motion tracking and image registration, scanning sources with faster speeds and lower resolution. For various disorders such as diabetic retinopathy, uveitis, vascular disorders, among others, the increased FOV showed demonstrably increased detection rates and diagnostic yield.Expert opinion: Increased FOV in OCTA imaging is a meaningful and impactful step in ophthalmic imaging. Overcoming the hardware-based limitations can potentially yield higher FOV without loss of important details. In addition to improvements in the hardware and available equipment, better software tools and image processing algorithms may greatly enhance the utility of UWF OCTA in care of patients with various retinochoroidal diseases.

Radiation-Induced Optical Coherence Tomography Angiography Retinal Alterations in Patients With Nasopharyngeal Carcinoma

Aim: The aim of the study was to investigate the early neurovascular alterations of the retina in radiation encephalopathy (RE) patients with normal-ranged visual acuity after radiotherapy for nasopharyngeal carcinoma.

Methods: Fifty-five RE patients and 54 healthy age-matched subjects were enrolled in this retrospective cross-sectional case–control study. The best corrected visual acuity (LogMAR) of the included eye should not be more than 0. The vessel density and thickness of different locations in the retina were acquired automatically using optical coherence tomography angiography (OCTA). The data were then compared between the RE patients and the controls. The location included the whole retina, the superficial vascular plexus (SVP)/the ganglion cell complex (GCC), the deep vascular plexus (DVP), and the choroid in the macular area, as well as the inside disc and peripapillary area in the optic nerve head (ONH). The risk factors in OCTA retinal impairments were analyzed using a backward multiple linear regression. The relationships between mean deviation (MD) and pattern standard deviation (PSD) in the visual field (VF) and the OCTA parameters were also analyzed in RE patients.

Results: The vessel density of the GCC was significantly reduced in RE patients compared with controls (p = 0.018), and the reductions were mainly shown in the parafoveal (p = 0.049) and perifoveal fields (p = 0.006). The thickness of the GCC was correspondingly reduced (whole image GCC mean thickness: p = 0.044; parafoveal thickness: p = 0.038; perifoveal thickness: p = 0.038). In addition, the sub-foveal choroidal thickness (p = 0.039) was also reduced in RE patients. The vessel density of the GCC (R² = 0.643) and DVP (R² = 0.777) had a significant positive correlation with high-density lipoprotein cholesterol (HDL-C) and apolipoprotein A1 (ApoA1) and had a significant negative correlation with age (GCC: HDL-C, β = 29.89, p = 0.005; ApoA1, β = 78.92, p = 0.002; age, β = −0.886, p = 0.001; DVP: HDL-C, β = 40.09, p = 0.003; ApoA1, β = 62.65, p = 0.013; age, β = −1.31, p = 0.001). The vessel density of the GCC also had a significant negative correlation with apolipoprotein B (ApoB) (β = −32.18, p = 0.006). In the VF, MD had a significant positive correlation with the vessel density inside disc (R² = 0.241, β = 0.304, p = 0.045), whereas PSD showed a significant negative correlation with the vessel density inside disc and the average GCC thickness, respectively (R² = 0.437; vessel density inside disc, β = −0.358, p = 0.004; average GCC thickness, β = −0.510, p < 0.001).

Conclusion: With the aid of OCTA, we found that neurovascular alterations of the retina may exist in RE patients with normal-ranged visual acuity. Herein, we suggest the implementation of OCTA to assist ophthalmologists in the early detection and consistent monitoring of radiation-related eye diseases to avoid delayed diagnosis.

Optical coherence tomography angiography characteristics of choroidal melanoma

PURPOSE

The purpose of this study is to evaluate tumour vasculature with optical coherence tomography angiography (OCTA) in malignant choroidal melanoma (CM).

MATERIALS AND METHODS

Patients with unilateral CM were included in this cross-sectional observational clinical study. Applying OCTA systems operating at 840-nm wavelengths, eyes with CM were imaged. The primary main outcome measures were OCTA images, qualitative evaluation of macular and tumour vasculature, quantitative vascular density (VD), perfusion density (PD) and the foveal avascular zone disruption.

RESULTS

The study included 11 patients with unilateral CM and contralateral unaffected eyes as the control group. Eyes of 11 patients with CM and contralateral unaffected eyes were imaged before brachytherapy and 5 patients were imaged post brachytherapy. CM is demonstrated dense, tortuous blood vessels, uneven thickness and relatively disorganised intratumoural vasculature. In 11 eyes with CM, the VD and PD in the macular area were significantly lower within affected eyes (131.333 ± 27.807%, 3.152 ± 0.714%, p < 0.0001) than in contralateral eyes (154.208 ± 5.599%, 3.662 ± 0.127%, p < 0.0001). The VD and PD in the tumour area (67.990 ± 34.899%, 1.617 ± 0.847%, p < 0.0001) were significantly lower when compared to the macular area of affected eyes (131.333 ± 27.807%, 3.152 ± 0.714%, p < 0.0001) and the macular area of contralateral eyes (154.208 ± 5.599%, 3.662 ± 0.127%, p < 0.0001). After radiation treatment, the VD and PD in five CM eyes (116.526 ± 7.598%, 2.438 ± 0.358%, p < 0.05) were significantly lower than before treatment (141.544 ± 14.645%, 3.327 ± 0.354%, p < 0.05). Tumour regression after radiation therapy for melanomas was associated with decreased vessel density.

CONCLUSIONS

OCTA can provide a dye-free, non-invasive, reliable method to monitor a variety of tumours, including CM for growth and vascularity. Upon OCTA, this could be helpful in evaluating the variety of tumour blood vessels before and after brachytherapy to judge the curative effect and whether the tumour recurred. Detection of the characteristic vascular features of CM by OCTA could make OCTA an assuring diagnostic modality to differentiate malignant lesions.

Quantifying Subclinical and Longitudinal Microvascular Changes Following Episcleral Plaque Brachytherapy Using Spectral Domain-Optical Coherence Tomography Angiography

PURPOSE

To assess longitudinal microvascular changes in eyes treated with I-125 episcleral plaque brachytherapy (EPB).

METHODS

High resolution OCT angiograms of the central 3×3mm macula were obtained from I-125 episcleral plaque brachytherapy treated and untreated fellow eyes of 61 patients. Capillary density (vessel skeleton density, VSD) and caliber (vessel diameter index, VDI) were quantified using previously validated semi-automated algorithms. Nonperfusion was also quantified as flow impairment regions (FIR). Exams from treated and fellow eyes obtained pre-treatment and at 6-month, 1-year, and 2-year intervals were compared using generalized estimating equation linear models. Dosimetry maps were used to evaluate spatial correlation between radiation dose and microvascular metrics.

RESULTS

At 6 months, treated eyes had significantly lower VSD (0.145 ± 0.003 vs 0.155 ± 0.002; p = 0.009) and higher FIR (2.01 ± 0.199 vs 1.46 ± 0.104; p = 0.010) compared to fellow eyes. There was a significant decrease in VSD and a corresponding increase in FIR even for treated eyes without clinically identifiable retinopathy at 6 months. VDI was significantly higher in treated eyes than in fellow eyes at 2 years (2.92 ± 0.025 vs 2.84 ± 0.018; p < 0.001). When our cohort was categorized into low dose radiation (<15Gy) and high dose radiation (>45Gy) to the fovea, there were significant differences in VSD and FIR between groups.

CONCLUSIONS

OCTA can be used to quantify and monitor EPB induced retinopathy, and can detect vascular abnormalities even in the absence of clinically observable retinopathy. OCTA may therefore be useful in investigating treatment interventions that aim to delay EPB-induced radiation retinopathy.

Chorioretinal Side Effects of Therapeutic Ocular Irradiation: A Multimodal Imaging Approach

Radiation chorioretinopathy, radiation maculopathy, and radiation optic neuropathy are the major complications of ophthalmic radiotherapy. Optical coherence tomography (OCT) and OCT angiography (OCTA) are revolutionary imaging methods, allowing the visualization of the retinal cellular architecture and the retinal vascular system, respectively. In recent years this multimodal imaging approach has been applied to several retinal disease, but its role in the clinical characterization of retinal complications secondary to ophthalmic radiotherapy has not yet been defined. The purpose of this review is to critically evaluate the role of OCT and OCTA in the clinical assessment of radiation-induced chorioretinopathy, maculopathy, and optic neuropathy.

Wide-Field (15 × 9 mm) Swept-Source Optical Coherence Tomography Angiography Following Plaque Radiotherapy of Choroidal Melanoma: An Analysis of 105 eyes

PURPOSE

The aim of this study was to evaluate retinal microvascular abnormalities following plaque radiotherapy of choroidal melanoma (CM) using wide-field swept-source optical coherence tomography angiography (OCTA).

DESIGN

Single-centre retrospective review.

METHODS

Retrospective case series of 105 CM patients treated with I-125 plaque radiotherapy and imaged with wide-field (15 × 9 mm) SS-OCTA from March 2018 to August 2018 at the Ocular Oncology Service, Wills Eye Hospital (Philadelphia, PA).

RESULTS

At mean follow-up of 49 months (range 4-297) after plaque radiotherapy, there were 52 eyes (50%) with clinically evident radiation retinopathy (CERR) and 53 eyes (50%) without CERR. Comparison (CERR vs controls) revealed foveal avascular zone enlargement (1.7 vs 0.23 mm, P = 0.03) and reduction of capillary vascular density (CVD) in the superficial and deep plexus in the total wide-field (43% vs 47%, P < 0.001, and 46% vs 48%, P = 0.001, respectively), peripapillary region (66% vs 77%, P < 0.001, and 66% vs 72%, P = 0.001, respectively), and papillomacular bundle (60% vs 68%, P < 0.001, and 61% vs 64%, P = 0.03, respectively). Comparison (no CERR vs controls) revealed nonsignificant foveal avascular zone enlargement (1.20 vs 0.23 mm, P = 0.16) and reduction of CVD in the superficial plexus (46% vs 47%, P = 0.008), and not the deep plexus (48% vs 48%, P = 0.42) of the total wide-field. Comparison of irradiated eyes (CERR vs no CERR) showed reduction of CVD in the superficial and deep plexus of the total wide-field (43% vs 46%, P < 0.006, and 46% vs 48% P < 0.02, respectively), peripapillary region (66% vs 74%, P < 0.001, and 66% vs 72% P < 0.01, respectively), and superficial plexus in the papillomacular bundle (60% vs 65%, P = 0.03).

CONCLUSIONS

Following plaque radiotherapy for choroidal melanoma, wide-field swept-source optical coherence tomography angiography demonstrates retinal microvascular abnormalities in the CVD in eyes with and without CERR. These findings are important in early detection and monitoring of radiation retinopathy.

Quantitative optical coherence tomography angiography: A review

As a new optical coherence tomography (OCT) modality, OCT angiography (OCTA) provides a noninvasive method to detect microvascular distortions correlated with eye conditions. By providing unparalleled capability to differentiate individual plexus layers in the retina, OCTA has demonstrated its excellence in clinical management of diabetic retinopathy, glaucoma, sickle cell retinopathy, diabetic macular edema, and other eye diseases. Quantitative OCTA analysis of retinal and choroidal vasculatures is essential to standardize objective interpretations of clinical outcome. Quantitative features, including blood vessel tortuosity, blood vessel caliber, blood vessel density, vessel perimeter index, fovea avascular zone area, fovea avascular zone contour irregularity, vessel branching coefficient, vessel branching angle, branching width ratio, and choroidal vascular analysis have been established for objective OCTA assessment. Moreover, differential artery–vein analysis has been recently demonstrated to improve OCTA performance for objective detection and classification of eye diseases. In this review, technical rationales and clinical applications of these quantitative OCTA features are summarized, and future prospects for using these quantitative OCTA features for artificial intelligence classification of eye conditions are discussed.

OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY DETECTS SUBCLINICAL RADIAL PERIPAPILLARY CAPILLARY DENSITY REDUCTION AFTER PLAQUE RADIOTHERAPY FOR CHOROIDAL MELANOMA

PURPOSE

To evaluate radial peripapillary capillary density (RPCD) in irradiated eyes without radiation papillopathy clinically.

METHODS

Patients treated with plaque radiotherapy for unilateral choroidal melanoma without radiation papillopathy clinically received optical coherence tomography and optical coherence tomography angiography imaging at ∼12- to 24-month follow-up. Comparison of RPCD globally and meridian closest to plaque and meridian farthest to plaque of irradiated versus nonirradiated eyes was performed.

RESULTS

Mean age was 55 years (n = 10). Mean largest basal diameter and thickness were 10.1 and 4.4 mm, respectively. Mean radiation dose to the optic nerve head and foveola was 41.7 and 66.2 Gy, respectively. No radiation papillopathy was detected by ophthalmoscopy throughout follow-up (mean:14 months). Radial peripapillary capillary density was significantly reduced globally (all P < 0.02). Meridian closest to plaque RPCD was significantly reduced (P < 0.01), but not meridian farthest to plaque RPCD (P = 0.07). Circumpapillary retinal nerve fiber layer thickness was not significantly reduced (P > 0.26). Radiation dose to the optic nerve head was correlated with meridian closest to plaque RPCD reduction (r = 0.76; P < 0.01). Mean radiation dose to the optic nerve head for <5% and ≥5% RPCD reductions was 35.9 ± 12.2 and 55.2 ± 6.4 Gy, respectively.

CONCLUSION

Radial peripapillary capillary density reduction was found in irradiated eyes before clinical evidence of radiation papillopathy and circumpapillary retinal nerve fiber layer thickness reduction. Radial peripapillary capillary density reduction is correlated to plaque location and radiation dose to the optic nerve head.

Longitudinal Detection of Radiation-Induced Peripapillary and Macular Retinal Capillary Ischemia Using OCT Angiography

PURPOSE

To study longitudinal changes in retinal capillary circulation in eyes treated with iodine 125 (I¹²⁵) plaque brachytherapy for uveal melanoma using OCT angiography (OCTA).

DESIGN

Longitudinal prospective study of 21 patients undergoing treatment for uveal melanoma with I¹²⁵ plaque brachytherapy. Eyes with melanoma were imaged with OCTA before treatment and at 12-month intervals until 2 years after brachytherapy.

PARTICIPANTS

After institutional review board approval, participants were enrolled prospectively from an academic ocular oncology clinic.

METHODS

Peripapillary (4.5 × 4.5-mm) and macular (3 × 3-mm) OCTA scans were acquired with AngioVue (Optovue, Inc, Fremont, CA).

MAIN OUTCOME MEASURES

The peripapillary nerve fiber layer plexus capillary density (NFLP_CD), macular superficial vascular complex vessel density (mSVC_VD), and foveal avascular zone (FAZ) area were calculated.

RESULTS

Before treatment, no significant difference was found in the NFLP_CD, mSVC_VD, or FAZ area between eyes with melanoma and normal fellow eyes. By 24 months, 11 eyes had developed clinical signs of radiation retinopathy, radiation optic neuropathy, or both. In treated eyes, the NFLP_CD (48.4±4.1%) was reduced at 12 months (46.7±5.0%; P = 0.04, Wilcoxon signed-rank test) and 24 months (44.5±6.1%; P < 0.001). Similarly, the mSVC_VD (48.4 2±3.6%) was reduced in treated eyes at 12 months (43.5±5.9%; P = 0.01) and 24 months (37.4±9.1%; P < 0.001). The FAZ area (0.26±0.11 mm²) increased in treated eyes at 12 months (0.35±0.22 mm²; P = 0.009) and 24 months (0.81±1.03 mm²; P = 0.001). When only eyes with clinically evident radiation changes were evaluated, the changes in NFLP_CD, mSVC_VD, and FAZ area were more pronounced. OCT angiography measurements correlated with both radiation dose and visual acuity. The mSVC_VD measured at 12 months was found to predict the development of clinically apparent radiation retinopathy within 1 year.

CONCLUSIONS

OCT angiography demonstrated early emergence of peripapillary and macular capillary vasculature changes after I¹²⁵ plaque brachytherapy. OCT angiography provided a quantitative measurement of retinal capillary changes associated with ischemia that correlated with visual acuity and radiation dose and may predict future development of radiation-induced retinal toxicity.

Projection-Resolved Optical Coherence Tomographic Angiography of Retinal Plexuses in Retinitis Pigmentosa

PURPOSE

To use projection-resolved optical coherence tomographic angiography (PR-OCTA) to characterize the microvascular changes in 3 distinct retinal plexuses in retinitis pigmentosa (RP) patients.

DESIGN

Prospective cross-sectional study.

METHODS

A commercial 70-kHz spectral-domain optical coherence tomography (OCT) system was used to acquire 6-mm macular scans from RP patients and age-matched healthy participants at a tertiary academic center. Blood flow was detected using a commercial version of split-spectrum amplitude-decorrelation angiography (SSADA) algorithm. The PR-OCTA algorithm was used to suppress projection artifacts and resolve microvasculature in 3 plexuses around the macula. Vessel density was calculated from en face OCTA of the parafoveal and perifoveal regions in each of the 3 plexuses, as well as the all-plexus inner retinal slab. Inner and outer retinal thicknesses were measured form structural OCT scans. Generalized estimating equations and Spearman's rank correlation statistical methods were used.

RESULTS

Forty-four eyes from 26 RP patients and 34 eyes from 26 healthy subjects were included. Significant reduction in vessel density was detected in the perifovea but not the parafovea of inner retinal slab of RP patients (P = .001 and P = .56, respectively) compared to controls. We also found deeper retinal plexuses (intermediate and deep capillary plexuses, ICP and DCP) were primarily damaged by RP, compared to superficial vascular complex (SVC). Significant thickening of the inner retina and thinning of the outer retina were also observed. Strong correlation was found between the vessel density in the perifoveal ICP and DCP and outer retinal thickness in RP patients with no history of cystoid macular edema.

CONCLUSIONS

PR-OCTA enables the detection of microvascular changes in the perifoveal regions of the ICP and DCP in RP, with relative sparing of the SVC. OCT and OCTA parameters might be able to provide better understanding of the pathophysiology of the disease, as well as monitoring disease progression and the response to experimental treatments.