Optical coherence tomography angiography-derived flow density: a review of the influencing factors.

Research interest in the possibility of quantifying macular and optic nerve head perfusion through optical coherence tomography angiography (OCTA) is rapidly advancing. Numerous scientific trials have furthered our understanding of the capabilities and the limitations of this novel technology, while applying OCTA to various ocular pathologies. In recent years, different parameters such as age, gender, intraocular pressure, spherical equivalent, physical activity, systemic diseases, and medication have been shown to have a significant impact on quantitative OCTA metrics. Since OCTA is likely to remain a "hot topic" in the near future, it is crucial to be aware of influencing factors in order to ensure correct interpretation of imaging results. This article reviews the factors currently known to influence flow density (FD) as measured by OCTA in healthy eyes.

SALUS-A Study on Self-Tonometry for Glaucoma Patients: Design and Implementation of the Electronic Case File.

BACKGROUND: In times of omnipresent digitization and big data, telemedicine and electronic case files (ECFs) are gaining ground for networking between players in the health care sector. In the context of the SALUS study, this approach is applied in practice in the form of electronic platforms to display and process disease-relevant data of glaucoma patients. OBJECTIVES: The SALUS ECF is designed and implemented to support data acquisition and presentation, monitoring, and outcome control for patients suffering from glaucoma in a clinical setting. Its main aim is to provide a means for out- and inpatient exchange of information between various stakeholders with an intuitive user interface in ophthalmologic care. Instrument data, anamnestic data, and diagnostic assessments need to be accessible and historic data stored for patient monitoring. Quality control of the data is ensured by a reading center. METHODS: Based on an intensive requirement analysis, we implemented the ECF as a web-based application in React with a Datomic back-end exposing REST and GraphQL APIs for data access and import. A flexible role management was developed, which addresses the various tasks of multiple stakeholders in the SALUS study. Data security is ensured by a comprehensive encryption concept. We evaluated the usability and efficiency of the ECF by measuring the durations medical doctors need to enter and work with the data. RESULTS: The evaluation showed that the ECF is time-saving in comparison to paper-based assessments and offers supportive monitoring and outcome control for numerical and imaging-related data. By allowing patients and physicians to access the digital ECF, data connectivity as well as patient autonomy were enhanced. CONCLUSION: ECFs have a great potential to efficiently support all patients and stakeholders involved in the care of glaucoma patients. They benefit from the efficient management and view of the data tailored to their specific role.

[Münster standard: modified Paul® implantation in a condition following Preserflo® MicroShunt implantation. Video article]. / Münsteraner Standard: modifizierte PAUL®-Implantation bei Zustand nach PreserFlo® MicroShunt-Implantation. Videobeitrag.

OBJECTIVE OF SURGERY: The aim of this surgical technique is the modified placement of a Paul® implant (Fa. Advanced Ophthalmic Innovations, Singapur) in eyes after failure of Preserflo® MicroShunt (Fa. Santen, Osaka, Japan) implantation for the best possible adjustment of the intraocular pressure. INDICATIONS: The technique presented here is intended for patients suffering from more complex glaucomas, which were unsuccessfully previously treated with a Preserflo® Microshunt (Santen Inc.). SURGICAL TECHNIQUE: The special feature of the Münster standard is the choice of the surgical field and the waiver of a further tunnel placement. The patients receive a Paul® implant in the same quadrant as the previously inserted Preserflo® MicroShunt implant (superior temporal). The latter is explanted after preparation of the conjunctiva and priming of the Paul® implant with a Prolene 6.0 suture and fixation of the plate. In order to carry out the implantation of the Paul® tube through the existing 25-gauge tunnel, the latter is dilated laterally with an iris spatula under positioning of the anterior chamber. A surgical video, which is available online, shows the surgical technique in detail. ADVANTAGES OF THE MüNSTER STANDARD: The superior temporal surgical access promises easier handling. The fact that there is no need for a new tunnel effectively saves surgery time and is expected to reduce endothelial cell loss as only one tube remains in place in comparison to two anterior chamber tubes.

Influence of mydriasis on optical coherence tomography angiography imaging in patients with age-related macular degeneration.

PURPOSE: To evaluate the effect of topical mydriatic eye drops on optical coherence tomography angiography (OCTA) parameters in patients with age-related macular degeneration (AMD). METHODS: 27 eyes of 27 patients suffering from AMD were included in this cross-sectional study. Patients with ≥-4.5 diopters spherical equivalent, corneal opacities or dense cataract preventing high-quality imaging were excluded. Whole-en-face scans of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) in the central 3x3mm foveal region as well as whole-en-face and peripapillary scans of the radial peripapillary capillaries (RPC) were generated using OCTA (AngioVue®, Optovue). Imaging was first conducted with patients' eyes in miosis, then in mydriasis after instillation of a dilating eye drop (0.5% tropicamide, 2.5% phenylephrine-HCl). Main outcome measures were flow density (FD), foveal avascular zone (FAZ), signal strength index (SSI) and motion artifact score (MAS). RESULTS: Our results reveal that in AMD patients there is no significant difference between FD measurements taken in miosis and those taken in mydriasis around the SCP (p = 0.198), DCP (p = 0.458), RPC whole-en-face (p = 0.275) and RPC peripapillary (p = 0.503). Measurements taken in these two states appear to be equivalent for assessment of FD (90%CI within ± 0.05). No significant difference was found either in the area of the FAZ (p = 0.338) or in the SSI (p = 0.371) before and after the instillation of tropicamide/phenylephrine. MAS was significantly lower after the application of mydriatic eye drops (p = 0.003). CONCLUSIONS: Our findings reveal that neither measurements of FD nor measurements of the FAZ area changed significantly in AMD patients after the application of tropicamide/phenylephrine. Since MAS improved significantly in dilation, mydriatic examination is recommended. Nevertheless, a comparison of OCTA metrics from images taken with different pupil states (miosis versus mydriasis) is valid for clinical trials.