Temporal Relationship Between Visual Field, Retinal and Microvascular Pathology Following 125I-Plaque Brachytherapy for Uveal Melanoma

Radiation effects on retinal layers revealed by OCT, OCT-A, and perimetry as a function of dose and time from treatment

Optical coherence tomography (OCT) has become a key method for diagnosing and staging radiation retinopathy, based mainly on the presence of fluid in the central macula. A robust retinal layer segmentation method is required for identification of the specific layers involved in radiation-induced pathology in individual eyes over time, in order to determine damage driven by radiation injury to the microvessels and to the inner retinal neurons. Here, we utilized OCT, OCT-angiography, visual field testing, and patient-specific dosimetry models to analyze abnormal retinal layer thickening and thinning relative to microvessel density, visual function, radiation dose, and time from radiotherapy in a cross-sectional cohort of uveal melanoma patients treated with 125I-plaque brachytherapy. Within the first 24 months of radiotherapy, we show differential thickening and thinning of the two inner retinal layers, suggestive of microvessel leakage and neurodegeneration, mostly favoring thickening. Four out of 13 eyes showed decreased inner retinal capillary density associated with a corresponding normal inner retinal thickness, indicating early microvascular pathology. Two eyes showed the opposite: significant inner retinal layer thinning and normal capillary density, indicating early neuronal damage preceding a decrease in capillary density. At later time points, inner retinal thinning becomes the dominant pathology and correlates significantly with decreased vascularity, vision loss, and dose to the optic nerve. Stable multiple retinal layer segmentation provided by 3D graph-based methods aids in assessing the microvascular and neuronal response to radiation, information needed to target therapeutics for radiation retinopathy and vision loss.

Mouse model of radiation retinopathy reveals vascular and neuronal injury

PURPOSE

To characterize the neuronal and vascular pathology in vivo and in vitro in a mouse model of radiation retinopathy.

METHODS

C57Bl/6J mice underwent cranial irradiation with 12 Gy and in vivo imaging by optical coherence tomography and of relative blood flow velocity by laser speckle flowgraphy for up to 3-6 months after irradiation. Retinal architecture, vascular density and leakage and apoptosis were analyzed by histology and immunohistochemistry before irradiation or at 10, 30, 240, and 365 days after treatment.

RESULTS

The vascular density decreased in the plexiform layers starting at 30 days after irradiation. No impairment in retinal flow velocity was seen. Subtle perivascular leakage was present at 10 days, in particular in the outer plexiform layer. This corresponded to increased width of this layer. However, no significant change in the retinal thickness was detected by OCT-B scans. At 365 days after irradiation, the nuclear density was significantly reduced compared to baseline. Apoptosis was detected at 30 days and less prominent at 365 days.

CONCLUSIONS

By histology, vascular leakage at 10 days was followed by increased neuronal apoptosis and loss of neuronal and vascular density. However, in vivo imaging approaches that are commonly used in human patients did not detect pathology in mice.

The prognostic implication of visual acuity at the time of uveal melanoma diagnosis

BACKGROUND

Visual outcomes after primary tumour treatment of uveal melanoma (UM) have been investigated repeatedly. This study evaluates the correlation between best-corrected visual acuity (BCVA) before treatment with clinicopathological factors and patient survival.

SUBJECTS/METHODS

Pre-treatment BCVA was examined in relation to tumour dimensions and location, and survival in a retrospective cohort of 1809 patients who underwent plaque brachytherapy. BCVA was also correlated to tumour histological factors in a second cohort of 137 enucleated eyes.

RESULTS

The mean BCVA of the tumour eye prior to plaque brachytherapy was LogMAR 0.42 (SD 0.46). Patients with low BCVA (LogMAR ≥ 1.00) did not differ in age (p = 0.19) and had similar frequency of ciliary body involvement (p = 0.99) but had tumours with greater apical thickness (p < 0.0001), greater diameter (p < 0.0001) and shorter distance to the optic disc and fovea (p < 0.0001). There were no significant relations between low BCVA and any of 13 examined tumour histological factors at a Bonferroni-corrected significance level (p > 0.004). Patients with low BCVA had greater incidence of UM-related mortality in competing risk analysis (p = 0.0019) and shorter overall survival (p < 0.0001). Low BCVA was also associated with increased hazard ratio (HR) for UM-related mortality in univariate analysis (HR 1.5, 95% confidence interval 1.2 to 1.9), but not in multivariate analysis with tumour size and location as covariates.

CONCLUSIONS

UM patients with low BCVA before primary tumour treatment have a worse prognosis, likely related to increased tumour dimensions. Future studies should examine the prognostic significance of BCVA in relation to macula-involving retinal detachment and genetic factors.

Deterioration of Visual Acuity after Brachytherapy and Proton Therapy of Uveal Melanoma, and Methods of Counteracting This Complication Based on Recent Publications

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. The eyeball is the most common extracutaneous location of melanoma. UM is a huge threat to a patient's life. It metastasizes distantly via blood vessels, but it can also spread locally and infiltrate extraocular structures. The treatment uses surgical methods, which include, among others, enucleation and conservative methods, such as brachytherapy (BT), proton therapy (PT), stereotactic radiotherapy (SRT), stereotactic radiosurgery (SRS), transpupillary thermotherapy (TTT) and photodynamic therapy. The key advantage of radiotherapy, which is currently used in most patients, is the preservation of the eyeball with the risk of metastasis and mortality comparable to that of enucleation. Unfortunately, radiotherapy very often leads to a significant deterioration in visual acuity (VA) as a result of radiation complications. This article is a review of the latest research on ruthenium-106 (Ru-106) brachytherapy, iodine-125 (I-125) brachytherapy and proton therapy of uveal melanoma that took into account the deterioration of eye function after therapy, and also the latest studies presenting the new concepts of modifications to the applied treatments in order to reduce radiation complications and maintain better visual acuity in treated patients.

Reduced blood flow by laser speckle flowgraphy after 125I-plaque brachytherapy for uveal melanoma

BACKGROUND

To determine whether reductions in retinal and choroidal blood flow measured by laser speckle flowgraphy are detected after 125I-plaque brachytherapy for uveal melanoma.

METHODS

In a cross-sectional study, retinal and choroidal blood flow were measured using laser speckle flowgraphy in 25 patients after treatment with 125I-plaque brachytherapy for uveal melanoma. Flow was analyzed in the peripapillary region by mean blur rate as well as in the entire image area with a novel superpixel-based method. Relationships between measures were determined by Spearman correlation.

RESULTS

Significant decreases in laser speckle blood flow were observed in both the retinal and choroidal vascular beds of irradiated, but not fellow, eyes. Overall, 24 of 25 patients had decreased blood flow compared to their fellow eye, including 5 of the 6 patients imaged within the first 6 months following brachytherapy. A significant negative correlation between blood flow and time from therapy was present.

CONCLUSIONS

Decreases in retinal and choroidal blood flow by laser speckle flowgraphy were detected within the first 6 months following brachytherapy. Reduced retinal and choroidal blood flow may be an early indicator of microangiographic response to radiation therapy.

Longitudinal optical coherence tomography angiography (OCT-A) in a patient with radiation retinopathy following plaque brachytherapy for uveal melanoma

Purpose

Patients with choroidal melanoma treated with brachytherapy lose vision over time due to radiation retinopathy and optic neuropathy. Newer imaging modalities such as optical coherence tomography angiography (OCT-A) may provide further insight into the ultrastructural vascular changes that occur over time. We studied the progressive OCT-A derived reduction in capillary density that occurred in the macula and juxtapapillary region of a patient treated with plaque brachytherapy for posterior uveal melanoma.

Methods

A patient with medium-sized choroidal melanoma in the inferonasal mid-periphery of the right eye was followed with OCT-A imaging in addition to standard imaging (color fundus photography, standardized echography, OCT) over a four-year time period following brachytherapy. Images were analyzed to measure vascular density in nine discrete areas of the macula at each time point as a function of region-specific radiation dose.

Results

OCT-A over time showed focal capillary loss and enlargement of the foveal avascular zone in addition to vascular re-modeling. These changes progressed over time despite improvement in the clinical markers of radiation retinopathy (cotton wool spots, retinal hemorrhages). Radiation dose significantly correlated with rate of reduction in vascular density assessed within 9 square sectors of the macula, and was greatest in sectors closest to the plaque, which had received the highest radiation dose. There was no change in the choriocapillaris flow area over time. The patient developed cystoid macular edema, but maintained 20/30 vision.

Conclusions and Importance

Longitudinal OCT-A demonstrates the microvascular changes that occur in response to radiation over time. Identification of these features may help define therapeutic windows to prevent vision loss associated with radiation retinopathy and optic neuropathy. Ongoing studies will describe a larger cohort of patients followed with this modality over time.