Functional and structural reliability of optic nerve head measurements in healthy eyes by means of optical coherence tomography angiography

Background and Objectives: the aim of the study was to evaluate the repeatability and reproducibility of optical microangiography (OMAG)-based optical coherence tomography angiography (OCTA) in the optic nerve head (ONH) and radial peripapillary capillary (RPC) perfusion assessment of healthy eyes. Materials and Methods: in this observational study, a total of 40 healthy subjects underwent ONH evaluation, using an OMAG-based OCTA system at baseline (T0), after 30 min (T1), and after 7 days (T2). The main outcome measures were the vessel density (VD) and flux index (FI) of the RPCs, as well as peri-papillary retinal nerve fibre layer (pRNFL) thickness. The analysis was performed by two observers independently. The coefficient of repeatability (CR), within the subject coefficient of variation (CVw) and intrasession correlation coefficient (ICC), to evaluate intrasession repeatability of measurements was calculated for each observer. Results: the high intrasession and intersession repeatability and reproducibility were assessed in the two observers for all three outcome measures. Of note, the CRs for the first and the second observer were 0.011 (95% confidence interval (CI) 0.009–0.014) and 0.016 (95% CI 0.013–0.020) for FI, 0.016 (95% CI 0.013–0.021) and 0.017 (95% CI 0.014–0.021) for VD, and 2.400 (95% CI 1.948–3.092) and 3.732 (95% CI 3.064–4.775) for pRNFL thickness, respectively. The agreement between them was excellent for pRNFL assessment and very good for FI and VD. Conclusion: OCTA has a great potential in the accurate assessment of ONH and peri-papillary microcirculation. It allows for repeated and reproducible measurements without multiple scans-related bias, thus guaranteeing an independent operator analysis with good reproducibility and repeatability

Angiographic biomarkers of filtering bleb function after XEN gel implantation for glaucoma: an optical coherence tomography-angiography study

Purpose: To evaluate, using optical coherence tomography-angiography (OCT-A), the vascular features of good bleb function after XEN gel implantation (XGI) for uncontrolled glaucoma. Methods: Forty-three patients (43 eyes), who underwent XGI, were enrolled. According to the intraocular pressure (IOP) reduction, patients were classified into Group 1 (21 eyes; success) and Group 2 (22 eyes; failure). Optical coherence tomography-angiography (OCT-A) was performed to image the vascularization of the conjunctival bleb-wall. The main outcomes were as follows: vessel displacement areas (VDAs), major vessel displacement area (MVDA; mm2), non-flow whole area (NFWA; mm2) and bleb-wall vessel density (BVD; %). Co-registered B-scans were also considered to evaluate the bleb-wall cyst-like structure density and area (BCSD, cysts/mm2; BCSA, mm2), and the bleb-wall thickness (BT, \ub5m). Results: Mean postoperative follow-up was 7.5\ua0\ub1\ua00.14\ua0months; Group 1 and 2 IOP were 14.0\ua0\ub1\ua02.5 and 25.3\ua0\ub1\ua02.1\ua0mmHg, respectively (p\ua0<\ua00.001). Greater VDA (p\ua0<\ua00.001), MVDA (p\ua0=\ua00.046) and NFWA (p\ua0=\ua00.001) values, and lower BVD (p\ua0<\ua00.001) was found in Group 1 compared to Group 2. Group 1 showed higher BSCD, BSCA and BT values compared to Group 2 (p\ua0<\ua00.001). Postoperative IOP positively correlated with BVD (r\ua0=\ua00.567; p\ua0=\ua00.003), but negatively with VDAs, MVDA (r\ua0=\ua0 120.581, p\ua0=\ua00.002; r\ua0=\ua0 120.619, p\ua0=\ua00.001, respectively), BCSD, BCSA (r\ua0=\ua0 120.580; p\ua0=\ua00.002; r\ua0=\ua0 120.664; p\ua0<\ua00.001) and BT (r\ua0=\ua0 120.627, p\ua0=\ua00.001). Conclusion: Successful filtration blebs after XGI present numerous and large areas of vessel displacement within the bleb-wall, along with a rarefied vascular network. These OCT-A features can be considered angiographic biomarkers of a good aqueous humour percolation through the bleb-wall layers

The Small Mars Satellite: a European small-size Mars lander

The Small Mars Satellite (SMS) is a proposed mission to Mars. The project is being funded by the General Studies Programme of the European Space Agency and has recently successfully concluded Phase 0 (feasibility study). The prime contractor is ALI S.c.a.r.l. (Naples), and the study team includes the University of Naples “Federico II” (UniNA), the Astronomical Observatory of Capodimonte (INAF-AOC, Naples) and the Space Studies Institute of Catalonia (IEEC, Barcelona). The objectives of the mission are technological and scientific, and consist in delivering to Mars a small lander carrying a dust particle analyser (DPA), developed by INAF-AOC, and an aerial drone (AD), proposed and designed by UniNA. The former shall perform in situ measurements of the size distribution and abundance of the dust particles suspended in the Martian atmosphere, whereas the latter shall execute multiple, low-altitude flights in the rarified environment of the red planet. The mission-enabling technology is an innovative deployable heat shield (DHS), whose original design is known as IRENE (Italian ReEntry NacellE), developed and patented by ALI

The Small Mars Satellite: a European small-size Martian lander

The Small Mars Satellite (SMS) is a proposed mission to Mars. The project is being funded by the General Studies Programme of the European Space Agency and has recently successfully concluded Phase 0 (feasibility study). The prime contractor is ALI S.c.a.r.l. (Naples), and the study team includes the University of Naples “Federico II” (UniNA), the Astronomical Observatory of Capodimonte (INAF-AOC, Naples) and the Space Studies Institute of Catalonia (IEEC, Barcelona). The objectives of the mission are technological and scientific, and consist in delivering to Mars a small lander carrying a dust particle analyser (DPA), developed by INAF-AOC, and an aerial drone (AD), proposed and designed by UniNA. The former shall perform in situ measurements of the size distribution and abundance of the dust particles suspended in the Martian atmosphere, whereas the latter shall execute multiple, low-altitude flights in the rarified environment of the red planet. The mission-enabling technology is an innovative deployable heat shield (DHS), whose original design is known as IRENE (Italian ReEntry NacellE), developed and patented by ALI. The core characteristics of SMS are the low cost (target 120 M€) and the small size (320 kg), features which stand out with respect to previous Mars landers. This target puts strict requirements on the choice of the materials, the sizing of payloads and subsystems, their arrangement inside the spacecraft and the choice of the launcher. Complying with them has been extremely challenging. The reasons for a successful design include the benefits derived from the heritage of previous missions, the implementation of recently developed technology (e.g., the heat shield), and the adoption of COTS hardware and lightweight materials, on the one hand, and a close compliance with system’s engineering (SE) principles, on the other: from the mission objectives to the engineering solutions through requirements formulation and implementation, identification of alternative options, execution of engineering trade-offs and design iterations. Concurrent engineering (CE) has also been applied, not through the use of specialized digital facilities, but by adopting fruitful practices, such as: an efficient project management, frequent team meetings and interactions with the customer, sharing of a common database, and, in general, a constant effort towards critical thinking aiming at identifying weak points and formulating strategies for their improvement. This contribution starts with an illustration of the current state of the project from the mission concept to the design of the spacecraft (Section “Mission description”). The implementation of SE and CE methods is dealt with in specific sections (“Systems Engineering Issues” and “Concurrent Engineering”). A discussion on the experience, the lessons learnt and the future prospects of the project and its design methods closes the paper

The Small Mars System

The Small Mars System is a proposed mission to Mars. Funded by the European Space Agency, the project has successfully completed Phase 0. The contractor is ALI S.c.a.r.l., and the study team includes the University of Naples “Federico II”, the Astronomical Observatory of Capodimonte and the Space Studies Institute of Catalonia. The objectives of the mission are both technological and scientific, and will be achieved by delivering a small Mars lander carrying a dust particle analyser and an aerial drone. The former shall perform in situ measurements of the size distribution and abundance of dust particles suspended in the Martian atmosphere, whereas the latter shall demonstrate low-altitude flight in the rarefied planetary environment. The mission-enabling technology is an innovative umbrella-like heat shield, known as IRENE, developed and patented by ALI. The mission is also a technological demonstration of the shield in the upper atmosphere of Mars. The core characteristics of SMS are the low cost (120 M€) and the small size (320 kg of wet mass at launch, 110 kg at landing), features which stand out with respect to previous Mars landers. To comply with them is extremely challenging at all levels, and sets strict requirements on the choice of the materials, the sizing of payloads and subsystems, their arrangement inside the spacecraft and the launcher's selection. In this contribution, the mission and system concept and design are illustrated and discussed. Special emphasis is given to the innovative features and to the challenges faced in the development of the wor

Small Mars satellite: A low-cost system for Mars exploration

The Small Mars Satellite (SMS) is a low-cost mission to Mars, currently under feasibility studyfunded by the European Space Agency (ESA). The mission, whose estimated cost iswithin 120 MEuro,aims at delivering a smallLandertoMars using an innovativedeployable(umbrella-like)heat shield concept, known as IRENE (Italian ReEntry NacellE), developed and patented by ALI S.c.a.r.l., which is also the project's prime contractor. The Lander includes two small payloads, i.e.,a dust particle analyzer and an aerial drone. The former isbased on an instrument, developed by the Astronomical Observatory of Capodimonte (INAF-OAC), performing in-situ measurementsof the size distribution and abundance of dust particles suspended in the Martian atmosphere. The drone is being designed by the University of Naples and aims at demonstratingthe feasibility of low-altitude flight in the Martian atmosphere. The project also involves the Space Studies Institute of Catalonia (IEEC), responsible for launch and trajectory design. In the paper, we illustrate the results of the feasibility study of SMS, including adescription of themissionprofile, launch and escape phases, interplanetary trajectory, Mars approach, entry, descent and landing (EDL),and payload deployment and operations. The current baseline envisages launching to LEO with VEGA. Then, a dedicated propulsion module will provide a series of apogee raising maneuvers to place the vehicle on thehyperbolictrajectory to Mars. A targeting maneuver, provided by a cruise stage,will direct the spacecraft to the atmospheric entry point providing initial conditions suitable for the deployment of the heat shield. This will provideaballistic coefficientmuch lower than in previousMarsmissions, thus allowing to reach subsonic conditionswithoutthe use of a supersonic parachute. To demonstrate this, EDL and aero-thermo-dynamic analysesare performed with a 3-DoF modelof the entry trajectoryand high fidelityCFD and DSMC analysis tools. Finally,particular attention is devoted to the description of the deployable shield technology and verification