Alessandro Rabiolo

Vessel density analysis in patients with retinitis pigmentosa by means of optical coherence tomography angiography

Aims To describe the vascular abnormalities in patients affected by retinitis pigmentosa (RP) by means of optical coherence tomography angiography (OCT-A). Methods Cross-sectional case series; patients with RP presenting at the Medical Retina Service of the Department of Ophthalmology, University Vita-Salute San Raffaele in Milan were recruited. Inclusion criteria were: diagnosis of RP, clear ocular media, adequate pupillary dilation, and stable fixation. Patients underwent best-corrected visual acuity (BCVA), biomicroscopy, short-wavelength fundus autofluorescence (SW-FAF), and 3×3 Swept Source OCT-A. 30 healthy subjects were chosen as controls. The main outcome was identification of abnormalities in density of the superficial capillary plexus (SCP) and deep capillary plexus (DCP), along with abnormalities of the choriocapillaris (CC). Results 16 patients (32 eyes) were recruited (6 females, 37.4%). Mean age was 53±18 years; mean BCVA was 0.5±0.3 LogMAR. Vessel density analysis disclosed a statistical significant difference in the SCP (29.5±6.8 vs 34.1±4.3; p=0.009) and in the DCP (28.7±7.5 vs 35.5±5.7; p=0.001) between the patients and the controls. No difference was found at the level of the CC (51±4.4 vs 51.3±2.2; p=0.716). RP patients showed a bigger foveal avascular zone at the DCP level compared to controls (p<0.001). Conclusions This study showed that most of the vascular impairment in patients affected by RP localised in the DCP, with relative sparing of the SCP and CC. DCP alterations were more pronounced outside the hyper-autofluorescent ring on SW-FAF. Vascular impairment may preclude good treatment outcomes in RP patients.

Vascular abnormalities in patients with Stargardt disease assessed with optical coherence tomography angiography

Aims To describe the vascular abnormalities in patients affected by Stargardt disease (STGD1) by means of optical coherence tomography angiography (OCT-A). Methods Cross-sectional case series, with the following inclusion criteria: diagnosis of STGD1, clear ocular media, and stable fixation. Patients underwent best-corrected visual acuity (BCVA), biomicroscopy, applanation tonometry, short-wavelength fundus autofluorescence (SW-FAF) (HRA Heidelberg, Germany), 3×3 Swept Source OCT-A (Topcon Corporation, Japan). Foveal avascular zone (FAZ) area was manually outlined and removed from the vessel density analysis (ImageJ). Main outcome was vessel density assessment in the superficial capillary plexus (SCP), in the deep capillary plexus (DCP), and in the choriocapillaris (CC) of patients with STGD1. Results Nineteen patients (36 eyes) were recruited for the study (10 females, 52.6%). Mean age was 33±5.7 years and mean BCVA was 0.6±0.3 logarithm of the minimum angle of resolution. Thirty-six healthy age-matched subjects (one eye for each patient) acted as a control group. Qualitative analysis of OCT-A revealed areas of reduced vascular density in superficial and DCPs. CC showed focal defects partially corresponding to the flecks on SW-FAF imaging. Quantitative analysis of OCT-A disclosed a statistically significant difference in the density of the SCP (0.302±0.062 vs 0.365±0.042; p=0.0002) and the DCP (0.303±0.081 vs 0.399±0.045; p<0.001) compared with controls. To analyse CC, patients with STGD1 were divided into two groups, according to the presence of chorioretinal atrophy. Patients with atrophy showed significantly lower CC density compared with controls (p=0.0003) and patients without atrophy (p=0.001). Patients with STGD1 showed a larger FAZ at the SCP level compared with controls (p=0.012). Conclusions Vascular impairment in patients affected by STGD1 is concentrated in superficial and the deep retinal plexuses. Patients with atrophic changes have a greater reduction in CC density compared with controls (‘dark atrophy’). Morphological vascular evaluation may become an important step for predicting STGD1 treatment outcomes.

Choroid morphometric analysis in non-neovascular age-related macular degeneration by means of optical coherence tomography angiography

Aims To describe the vascular changes in patients affected by non-neovascular age-related macular degeneration (AMD), featuring reticular pseudodrusen (RPD), drusen, or both RPD and drusen by means of optical coherence tomography angiography (OCT-A). Methods Cross-sectional observational case series. Patients with non-neovascular AMD presenting at the Medical Retina Service of the Department of Ophthalmology, University Vita-Salute San Raffaele in Milan were recruited. Patients underwent best-corrected visual acuity, biomicroscopy, infrared reflectance, short-wavelength fundus autofluorescence and OCT-A (AngioPlex, CIRRUS HD-OCT 5000, Carl Zeiss Meditech, Dublin, USA). Main outcome was quantification of vessel density, stromal tissue, and vascular/stromal (V/S) ratio at the choriocapillaris (CC), the Sattler and Hallers and the whole choroid layers among different groups of patients with non-neovascular AMD by means of binarised OCT-A scans. Results 45 eyes of 34 patients were enrolled (15 eyes of 11 patients with RPD, group 1; 15 eyes of 11 patients with drusen, group 2; 15 eyes of 12 patients with mixed phenotype, group 3). The CC, the Sattler and Hallers and the whole choroid vessel density were reduced in all groups of patients (p=0.023, p=0.007 and p=0.011 in group 1, group 2 and group 3 for the CC; p=0.021, p=0.037 and p=0.043 in group 1, group 2 and group 3 for the Sattler and Hallers density; p=0.016, p=0.002 and p<0.001 in group 1, group 2 and group 3 for the choroidal density), with significantly lower V/S ratios compared with healthy controls. Conclusions Patients with non-neovascular AMD show significant choroidal vascular depletion and fibrotic replacement, suggesting a possible role in the pathogenesis and progression of the disease.

CLINICAL SPECTRUM OF MACULAR-FOVEAL CAPILLARIES EVALUATED WITH OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY.

Purpose: To describe macular-foveal capillaries (MFC) by means of optical coherence tomography angiography and to identify the clinical spectrum of this angiographic feature. Methods: Patients with MFC presenting at the Medical Retina & Imaging Unit of the Department of Ophthalmology, University Vita-Salute San Raffaele in Milan were recruited. Patients underwent a complete ophthalmologic examination that included slit-lamp examination, fundus examination, measurement of best-corrected visual acuity, fundus autofluorescence, and spectral-domain optical coherence tomography (Spectralis HRA + OCT; Heidelberg Engineering, Heidelberg, Germany). Fluorescein angiography was performed in selected cases. Optical coherence tomography angiography was performed through Zeiss prototype (AngioPlex, CIRRUS HD-OCT models 5000; Carl Zeiss Meditec, Inc, Dublin, OH). Results: Twelve eyes of 10 consecutive white patients (5 men and 5 women; 50%) presenting MFC were included. Mean age was 66.2 ± 10.2 years (range, 53–79 years); mean best-corrected visual acuity was 0.1 ± 0.13 logarithm of the minimum angle of resolution (range, 0–0.4 logarithm of the minimum angle of resolution, corresponding to 20/20 to 20/50). Mean central macular thickness was 348 ± 57.6 &mgr;m. Two patients were affected by macular pucker, two by postsurgical macular edema, two by age-related macular degeneration, one by diabetic retinopathy, one by dome-shaped macula, one presented with chronic serous chorioretinopathy, and one with branch artery occlusion. Six eyes disclosed a complete absence of the foveal avascular zone, whereas the six other cases showed a partial foveal avascularity. No significant difference was found between complete and incomplete MFC with regards to best-corrected visual acuity (P = 0.272) and central macular thickness (P = 0.870). Conclusion: Cases of persistent MFC are heterogeneous in demographic characteristics, fundus appearance, and visual function. However, MFC, presenting either as complete absence of the foveal avascular zone or only partial foveal avascularity, may complicate different retinal abnormalities or represents a coincident finding.

Optical coherence tomography angiography: evolution or revolution?

Fluorescein angiography (FA) and indocyanine green angiography (ICGA) are gold standard diagnostic tools to study retinal vessels in clinical practice. Both FA and ICGA require intravenous dye injection, which can result in nausea and, rarely, anaphylaxis [1,2]. Leakage of dye in the later frames of the angiogram is used to identify any injuries like retinal vascular abnormalities or choroidal macular neovascularization (MNV). Optical coherence tomography angiography (OCT-A) is a new method for visualizing the retinal vasculature and choroidal vascular network. It is a dye-free, rapid, and threedimensional (3D) method. OCT-A is based on algorithms that convert multiple A-scans to OCT-A images. OCT angiograms are co-registered with OCT B-scans that are obtained concurrently, allowing for visualization of both retinal flow and structure in tandem. Images are based on the concept that in a static eye the only moving structure in the fundus of the eye is blood flowing through its vessels and contrast is generated based on the difference between moving cells in the vasculature and the static surrounding tissue. Technology for OCT-A is based on different types of algorithm such as split-spectrum amplitude-decorrelation angiography (SSADA), optical microangiography (OMAG) or fullspectrum amplitude-decorrelation angiography (FSADA-ADA). SSADA technology splits the OCT image into different spectral bands, increasing the number of usable image frames and it is developed to minimize scanning time. OMAG is a recently developed imaging technique that produces 3D images of dynamic blood perfusion within micro-circulatory tissue beds at an imaging depth up to 2.0 mm [3,4]. Finally, FSADA-ADA technology guarantees clear differentiation between blood flow and static tissue without sacrificing axial resolution (i.e. depth resolution) in OCT images. Although OCT-A is a promising tool, it is currently affected by image artifacts, which may be at risk of misinterpretation by the clinician. As described by Spaide et al. [5], artifacts consist either in visualization of unwanted or loss of necessary information. The most common artifacts belonging to the former category are: (i) projection artifacts, where both a vascular or avascular structure is erroneously visualized in the tissue below (i.e. superficial retinal vessels projection in deeper retinal layers, intraretinal pigment, or highest part of drusen resembling vascular structure); (ii) eye-motion artifacts, seen as horizontal white lines in conjunction with lateral displacement of the image. Regarding the latter category of artifacts, most common are: (i) media opacity, masquerading vessels below; (ii) intraor subretinal deposit (i.e. drusenoid or vitelliform materials, blood), which can create a focal defect underneath; (iii) blood flow too slow or fast to be detected (i.e. microaneurysm). Several algorithms have been developed in order to deal with artifacts (i.e. eye tracking, motion artifacts subtraction, projection removal); however, many other artifacts can arise in the post-processing phase, including defect in layer segmentation in pathologic eyes (i.e. degenerative myopia, wide pigment epithelial detachment, tissue atrophy) or, paradoxically, generated by the artifacts-correction algorithms themselves (i.e. vessel doubling, stretch artifacts). Although clinical applications of OCT-A embrace the entire spectrum of chorioretinal diseases, the most promising fields are those vessel-related, including age-related macular degeneration (AMD), MNV, diabetic retinopathy, retinal vascular occlusion, inflammatory diseases, macular telengectasia. With regard to AMD, OCT-A permits to study MNV, including type 1 (subretinal pigment epithelium), type 2 (subretinal), type 3 (intraretinal, also known as retinal angiomatous proliferation), and polypoidal choroidal vasculopathy [6]. OCT-A can also demonstrate quiescent non-exudative neovascularizations even in asymptomatic patients [7,8]. The individuation of MNV prior to their activation may be useful to identify a population at risk of developing symptomatic AMD [7,8]. Morphological changes of vascular network following antiangiogenic treatment have been elucidated by OCTA. Huang and colleagues [9] observed MNV shrinkage 2 weeks after treatment, followed by MNV resumption at 4 weeks and fluid recurrence at 6 weeks. Assessment of exudative AMD activity with OCT-A is extremely attractive and, in the future, OCT-A may guide the timing of treatment prior to fluid recurrence. Another interesting application of OCT-A is the study of MNV in chronic central serous chorioretinopathy (CSCR), which seems to be more frequent than previously thought. OCTA can individuate MNV in CSCR with high specificity, sensitivity, and perfect agreement with FA [10]. However, abnormal

Optical Coherence Tomography Angiography Macular and Peripapillary Vessel Perfusion Density in Healthy Subjects, Glaucoma Suspects, and Glaucoma Patients

Purpose To evaluate macular and peripapillary vessel perfusion density (VD) in glaucoma suspects (GS) and glaucoma patients; to correlate ganglion cell-inner plexiform layer (GCIPL) and retinal nerve fiber layer (RNFL) thicknesses with macular and peripapillary VD; and to evaluate the diagnostic accuracy of the structural and vascular parameters. Methods A consecutive series of GS, glaucoma patients, and healthy subjects was prospectively recruited from July 1, 2016, to January 31, 2017. All subjects underwent standard automated perimetry, spectral-domain optical coherence tomography (OCT), and 6 × 6-mm optical coherence tomography angiography (OCT-A) centered on the fovea and optic nerve. Results Forty controls, 40 GS, and 40 glaucoma patients were enrolled. Peripapillary RNFL, GCIPL, and macular RNFL thicknesses significantly decreased in the glaucoma group compared to controls and GS (P < 0.01). Peripapillary VD in average and in the superior and inferior quadrants decreased in the glaucoma group (P ≤ 0.001); conversely, macular VD was not statistically different across groups (P > 0.05). At the peripapillary area, a correlation between RNFL thickness and VD was found; conversely, no statistically significant correlation was found between GCIPL thicknesses and macular VD (all P > 0.05) in all groups. Peripapillary RNFL and GCIPL showed higher diagnostic capacity compared to peripapillary and macular VDs. Conclusions Structural damage is evident both in the peripapillary and in macular areas. Vascular damage seems to be less prominent, as it was seen only for the glaucoma group and at the radial peripapillary plexus. Diagnostic abilities are excellent for structural variables, less so but still good for peripapillary VD, and poor for macular VD.

VesselJ: A New Tool for Semiautomatic Measurement of Corneal Neovascularization.

PURPOSE To quantify blood and lymph angiogenesis in mouse corneal flat mounts by means of a novel plug-in for ImageJ, called VesselJ, based on a dynamic threshold algorithm. METHODS Corneal neovascularization (CNV) was induced in the right corneas of 20 C57BL6/N mice by means of alkali burn (n = 10) or intrastromal sutures (n = 10). All corneal flat mounts were stained for blood vessels with CD31 and for lymphatics with LYVE1. Three independent operators measured blood and lymphatic CNV with both a published manual method (mCNV) and VesselJ (automatic method; aCNV). RESULTS Both methods showed a strong reliability, defined as intraclass correlation coefficient (ICC) > 0.90, in quantifying hemangiogenesis for sutures and alkali burn. However, reliability of lymphatic mCNV varied from moderate in alkali burn (ICC: 0.700) to poor in sutures (ICC: 0.415), whereas it remained high in aCNV (alkali ICC: 0.996; sutures ICC: 0.959). Among sutures, a significant correlation between mCNV and aCNV was found among all the three operators for blood vessels and just for one operator for lymphatic vessels (P < 0.001). In the alkali burn model, correlation between blood mCNV and aCNV was significant for all operators after excluding three noisy flat mounts (P < 0.001), whereas no significant correlation was seen for lymphatic vessels. CONCLUSIONS VesselJ is a semiautomatic, reliable, and fast method to quantify corneal hem- and lymphangiogenesis in corneal flat mounts. VesselJ can be easily used in the sutures model; it should be applied to other models (e.g., alkali burn) only after checking for background hyperfluorescence. Italian Abstract.

Early response to ranibizumab predictive of functional outcome after dexamethasone for unresponsive diabetic macular oedema

Purpose To analyse the effects of intravitreal dexamethasone implant in patients suffering from diabetic macular oedema (DME) on the basis of their visual and functional response to antivascular endothelial growth factor (VEGF) loading dose, in order to early shift to corticosteroids in poorly responding patients. Design Retrospective monocentric study. Methods Data of patients with diabetes shifted to 0.7 mg dexamethasone implant after three injections of ranibizumab (RNB) and followed-up to 12 months were reviewed. Main outcome was the evaluation of short-term changes after dexamethasone implant injection, stratifying patients on the basis of best-corrected visual acuity (BCVA) and central macular thickness (CMT) after RNB loading dose. Secondary outcome was to investigate clinical gain maintenance at long-term follow-up. Results Overall, 45 eyes of 45 patients (23 males, 51.1%), mean age 69.7±9 years, were included in the analysis. After 3 injections of RNB, 30 eyes (66.7%) had a poor visual response (−4.3±10.7 letters), while 15 eyes (33.3%) disclosed good visual outcome (+13.9±9.2 letters). Patients with poor visual response were associated with limited morphological improvement (p=0.04). After 1 month from dexamethasone, only poor responders showed relevant increase in BCVA (p=0.006) and reduction in CMT (p=0.002), in comparison to good visual response patients, featuring only minor clinical effects (p=0.3). The same trend was maintained up to 12 months, after a mean of 1.9±1.1 dexamethasone administrations. Conclusion Visual and anatomical responses after RNB loading dose are significant predictors of both early term and long-term visual acuity improvement after switching to corticosteroids in patients with DME unresponsive to anti-VEGF.

Ultra-wide-field fluorescein angiography in diabetic retinopathy: A narrative review

Fluorescein angiography (FA) is a useful examination in patients suffering from diabetic retinopathy (DR). Traditional angiograms explore 30°-50° of the retina at once; however, visualization of peripheral retina is fundamental in order to assess nonperfused areas, vascular leakage, microvascular abnormalities, and neovascularizations. In order to expand the field of view, wide-field and ultra-wide-field imaging has been developed allowing to image up to 200° of retinal surface in one single shot. The aim of this narrative review was to provide an overview of the role of the most recent technique of ultra-wide-field fluorescein angiography in DR.

Deep Sclerectomy With Mitomycin C and Injectable Cross-linked Hyaluronic Acid Implant: Long-term Results

Purpose:To evaluate the long-term efficacy and safety of deep sclerectomy (DS) augmented with mitomycin C (MMC) and injectable cross-linked hyaluronic acid implant (Healaflow) in medically refractory glaucoma patients. Materials and Methods:Our study included 96 eyes of 83 consecutive patients with open-angle glaucoma undergoing MMC-DS with injectable cross-linked hyaluronic acid implant. Mean follow-up was 28.6±20.0 months. Variables analyzed were: intraocular pressure (IOP), best-corrected visual acuity, mean number of antiglaucomatous drugs, execution of postoperative maneuvres (goniopuncture, bleb needling, and laser lysis of scleral flap sutures). Tonometric success was defined by 2 different thresholds, specifically IOP⩽21 mm Hg (criterion A) and ⩽15 mm Hg (criterion B). The procedure was defined as a qualified success if reached with medication and as a complete success if reached without. Results:For criterion A, qualified and complete success rates were 96% and 94%, respectively, at 12 months, 95% and 92% at 24 months, and 92% and 89% at 36 months. For criterion B, qualified and complete success rates were 75% and 75%, respectively, at 12 months, 62% and 60% at 24 months, and 59% and 58% at 36 months. Goniopuncture was performed in 56 eyes (58%), bleb needling with 5-fluorouracil injection in 4 eyes (5.1%), and laser release of scleral flap sutures in 4 eyes (4%). Six eyes required additional filtering surgery. Conclusion:DS with Healaflow and MMC seems to be an effective and safe technique to lower IOP in patients affected by open-angle glaucoma, with few postoperative complications.