Photocoagulation or sham laser in addition to conventional anti-VEGF therapy in macular edema associated with TelCaps due to diabetic macular edema or retinal vein occlusion (TalaDME): a study protocol for a multicentric, French, two-group, non-commercial, active-control, observer-masked, non-inferiority, randomized controlled clinical trial.

BACKGROUND: Macular edema (ME) results from hyperpermeability of retinal vessels, leading to chronic extravasation of plasma components into the retina and hence potentially severe visual acuity loss. Current standard of care consists in using intravitreal injections (IVI), which results in a significant medical and economic burden. During diabetic retinopathy (DR) or retinal vein occlusion (RVO), it has recently been shown that focal vascular anomalies (capillary macro-aneurysms, also termed TelCaps) for telangiectatic capillaries may play a central role in the onset, early recurrence, and/or persistence of ME. Since targeted photocoagulation of TelCaps may improve vision, identification, and photocoagulation of TelCaps, it may represent a way to improve management of ME. OBJECTIVE: The Targeted Laser in (Diabetic) Macular Edema (TalaDME) study aims to evaluate whether ICG-guided targeted laser (IGTL), in association with standard of care by IVI, allows reducing the number of injections during the first year of treatment compared with IVI only, while remaining non-inferior for visual acuity. METHODS: TalaDME is a French, multicentric, two-arms, randomized, sham laser-controlled, double-masked trial evaluating the effect of photocoagulation of TelCaps combined to IVI in patients with ME associated with TelCaps. Patients with vision loss related to center involved ME secondary to RVO or DR and presenting TelCaps are eligible. Two hundred and seventy eyes of 270 patients are randomized in a 1:1 ratio to standard care, i.e., IVI of anti-VEGF solely (control group) or combined with IGTL therapy (experimental group). Stratification is done on the cause of ME (i.e., RVO versus diabetes). Anti-VEGF IVI are administered to both groups monthly for 3 months (loading dose) and then with a pro re nata regimen with a monthly follow-up for 12 months. The primary endpoint will be the number of IVI and the change in visual acuity from baseline to 12 months. Secondary endpoints will be the changes in central macular thickness, impact on quality of life, cost of treatment, and incremental cost-utility ratio in each groups. KEY SAFETY: Rare but severe AE linked to the use of IVI and laser, and previously described, are expected. In the sham group, rescue laser photocoagulation may be administered by the unmasked investigator if deemed necessary at month 3. DISCUSSION: The best management of ME associated with TelCaps is debated, and there have been no randomized study designed to answer this question. Given the fact that TelCaps may affect 30 to 60% of patients with chronic ME due to DR or RVO, a large number of patients could benefit from a specific management of TelCaps. TalaDME aims to establish the clinical and medico-economic benefits of additional targeted laser. The results of TalaDME may raise new recommendations for managing ME and impact healthcare costs. TRIAL REGISTRATION: EudraCT: 2018-A00800-55/ NCT03751501. Registration date: Nov. 23, 2018.

Early remodeling and loss of light-induced dilation of retinal small arteries in CADASIL.

A major hurdle to therapeutic development in cerebral small vessel diseases is the lack of in-vivo method that can be used repeatedly for evaluating directly cerebral microvessels. We hypothesised that Adaptive Optics (AO), which allows resolution images up to 1-2 µm/pixel at retinal level, could provide a biomarker for monitoring vascular changes in CADASIL, a genetic form of such condition. In 98 patients and 35 healthy individuals, the wall to lumen ratio (WLR), outer and inner diameter, wall thickness and wall cross-sectional area were measured in a parapapillary and/or paramacular retinal artery. The ratio of vessel diameters before and after light flicker stimulations was also calculated to measure vasoreactivity (VR). Multivariate mixed-model analysis showed that WLR was increased and associated with a larger wall thickness and smaller internal diameter of retinal arteries in patients. The difference was maximal at the youngest age and gradually reduced with aging. Average VR in patients was less than half of that of controls since the youngest age. Any robust association was found with clinical or imaging manifestations of the disease. Thus, AO enables the detection of early functional or structural vascular alterations in CADASIL but with no obvious link to the clinical or imaging severity.

Confocal microscopy of telangiectatic capillaries (TelCaps) and other features of microvascular remodeling following branch retinal vein occlusion.

Branch retinal vein occlusion (BRVO) is a frequent retinal vascular disease that may cause extensive microvascular remodeling leading to severe visual impairment. Little is known regarding the histology of non-neovascular microvascular remodeling. Here, we examined by confocal microscopy the structure of retinal microvessels of a donor eye with longstanding BRVO. The post-mortem retina of a 91-year-old woman that had superotemporal BRVO for 2 years was examined by confocal microscopy after anti-collagen IV (collIV), alpha-smooth muscle cell (αSMA), and anti-von Willebrand factor (vWf) immunolabeling. In the retinal quadrant affected by BRVO, extensive vascular remodeling affected all vessels, from arterioles to venules, including the foveal avascular zone. Most affected vessels were either irregularly dilated or, on the opposite, reduced to micrometric-size CollIV positive, vWf negative, nuclear-staining negative strings. Telangiectatic capillaries of various sizes and shapes were seen, the largest one (233 µm) being located in the parafoveal area. Some telangiectatic capillaries had a thick, multilayered vWf- and CollIV-positive wall, that often occluded the lumen. Other features included double-channeled arterioles. The majority of microvascular abnormalities were devoid of nuclear staining, suggesting extensive loss of endothelial cells. We describe the spectrum of microvascular abnormalities upstream of a longstanding BRVO. This spectrum comprises a large parafoveal telangiectatic capillary corresponding to what has been previously clinically defined as TelCap. The absence of intraluminal nuclear staining in the majority of abnormal vessels raises the hypothesis that the loss of endothelial cells plays a crucial role in the development of the different manifestations of capillary remodeling. The presence of vWF in de-endothelialized vessels suggests deposition of plasma, hence that they may remain perfused. Our work may help to understand the clinical imaging features of TelCaps.

Structural and functional analysis of retinal vasculature in HANAC syndrome with a novel intronic COL4A1 mutation.

PURPOSE: Mutations of the COL4A1 gene, a major structural protein of vessels, may cause hereditary angiopathy with nephropathy, aneurysms and muscle cramps (HANAC) syndrome. The vascular structure and function of patients with HANAC is poorly known. Here, we report a family with HANAC syndrome associated to a previously unreported mutation in COL4A1. The structure and function of retinal vessels were detailed by adaptive optics ophthalmoscopy (AOO) and optical coherence tomography (OCT) angiography. METHODS: Clinical data from six affected individuals (43 to 72 years old) from a single family comprising two generations were collected. Imaging charts including conventional fundus imaging, OCT-angiography and AOO in static and dynamic (flicker) mode were reviewed. DNA sequencing was done in the proband. RESULTS: DNA sequencing of the proband revealed a heterozygous deletion of COL4A1 (NM_001845) at position 1120 in the intron 20 resulting in the loss of splicing donor site for exon 20 (c.1120 + 2_1120 + 8del heterozygote). Four patients had arterial hypertension, and three had kidney dysfunction, one of which under dialysis. By fundus examination, five had typical retinal arteriolar tortuosity with arteriolar loops. Wall-to-lumen ratio of arteries was within normal limits, that is, lower than expected for hypertensive patients. Several foci of arteriolar irregularities were noted in the two oldest patients. In three affected subjects, evaluation of the neurovascular coupling showed a higher flicker-induced vasodilation than a control population (6 % to 11 %; n < 5 %). CONCLUSIONS: Structural and dynamic analysis of retinal vessels in a HANAC family bearing a previously unreported intronic COL4 mutation was done. In addition to arteriolar tortuosity, we found reduced wall-to-lumen ratio, arteriolar irregularity and increased vasodilatory response to flicker light. These abnormalities were more marked in the oldest subjects. This abnormal flicker response affected also non-tortuous arteries, suggesting that microvascular dysfunction extends beyond tortuosity. Such explorations may help to better vascular dysfunction related to HANAC and hence better understand the mechanisms of end-organ damage.

Indocyanine green angiography for identifying telangiectatic capillaries in diabetic macular oedema.

AIMS: During diabetic macular oedema (DME), a spectrum of capillary abnormalities is commonly observed, ranging from microaneurysms to large microvascular abnormalities. Clinical evidence suggests that targeted photocoagulation of large microvascular abnormalities may be beneficial, but their detection is not done in a routine fashion. It was reported that they are better identified by indocyanine green angiography (ICGA) than by fluorescein angiography. Here, we investigated the prevalence and ICGA and optical coherence tomography (OCT) features of retinal microvascular abnormalities in a group of patients with DME. METHODS: Observational study. The fundus photographs, ICGA and structural and angiographic OCT charts of 35 eyes from 25 consecutive patients with DME were reviewed. RESULTS: 22 eyes (63%) had at least one focal area of microvascular abnormalities showing prolonged indocyanine green (ICG) staining (ie, beyond 10 mins after injection). In particular, all eyes (n=9) with circinate hard exudates showed foci of late ICG staining. These areas were either isolated globular capillary ecstasies or a cluster of ill-defined capillary abnormalities. They were located at a median distance of 2708 µm from the fovea (range: 1064-4583 µm). Their diameter ranged from 153 to 307 µm. During ICGA, 91% showed increased their contrast and apparent size in late frames, whereas 79% of microaneurysms showed reduced contrast on late frames. OCT angiography was not contributive for the detection of these lesions. CONCLUSION: Late ICG staining revealing large microvascular abnormalities is commonly observed during DME. Because of their specific angiographic and OCT features relative to microaneurysms, we propose to name them telangiectatic capillaries (TelCaps).