Clinical Characterization of Suprachoroidal Injection Procedure Utilizing a Microinjector across Three Retinal Disorders

Abstract

Purpose: This study assessed physician-investigator experience with suprachoroidal (SC) injections, an investigational therapeutic administration technique using a 900 or 1100 µm microneedle to inject drugs into the SC space.

Methods: Datasets from six clinical trials across three diseases (noninfectious uveitis; diabetic macula edema, and retinal vein occlusion) were assessed. In addition to a user survey, retrospective correlations were performed between procedural variables (needle length), and demographics, and ocular characteristics.

Results: In the user survey, 84% (31/37) of physician-investigators did not perceive the SC injections to be meaningfully more challenging than other ocular injections. For the correlation analysis, the 900 µm needle was used for 71% (412/581) of baseline injections, and switching to the longer needle occured in the remaining 29% of baseline injections. No statistical correlations were found between needle lengths and age, race, disorder, refraction, visual acuity, intraocular pressure, retinal central subfield thickness, or lens status. Patient gender and needle length were statistically associated, with 76% (210/275) versus 66% (202/306) of injections administered with 900 µm needles for female and male gender, respectively. Injection quadrant correlated to needle length with 78% (214/275) of superotemporal quadrant injections administered with 900 µm needles, compared with 65% (73/113) of inferotemporal quadrant injections.

Conclusions: Both the user survey and the correlation analysis demonstrated that SC injection is well accepted by physician-investigators, and the two needle lengths accommodate a wide range of anatomic and demographic variables.

Translational relevance: These results, along with the presented ex-vivo endoscopic imaging, suggest that SC injection could be readily adopted in clinical practice for targeted compartmentalized delivery of ocular therapeutics.

Keywords: SCS; microinjector; microneedle; suprachoroidal.

Conflict of interest statement

Disclosure: Chen-rei Wan, Clearside (E, I); B. Kapik, Clearside (E, I); C.C. Wykoff, Clearside (F, C); C.R. Henry, Clearside (C), Alimera (C), Bausch & Lomb (C); M.R. Barakat, Bausch & Lomb (C), Regenxbio (C), Clearside (R); M. Shah, Clearside (F); R.V. Andino, Clearside (E, I); T.A. Ciulla, Clearside (E, I)

Copyright 2020 The Authors.

Figures

Figure 1.

Key suprachoroidal injection techniques. The needle must be inserted perpendicularly to the ocular surface because the free needle length is on the order of the thickness of the sclera. The needle hub is designed to compress on the ocular surface to reduce the thickness of the conjunctiva and to form an indentation. Because the SCS, a potential space, is opened as the injection occurs, slow injection is essential once loss of resistance is experienced. It is recommended for the physician to first attempt the SC injection with the shorter needle. The two needle lengths of 900 µm and 1100 µm are offered to accommodate variations in patient anatomy. If persistent resistance is felt, then the longer needle may be used to complete the injection, after ensuring appropriate injection technique.

Figure 2.

Correlations between procedural variables (900 µm vs. 1100 µm needles) and (a) gender or (b) administration quadrant (univariate analysis). Among all evaluated variables (disorder, refraction, IOP, lens status, gender, age, race, and quadrant of administration), statistical significance was only observed in (a) gender and (b) quadrant of administration. Evaluating by gender, the 900 µm needle was used for 76% (209 of 275) of the female patients compared to 66% (202 of 306) of the male patients. Furthermore, there was a statistically significant correlation between the needle usage and the administration quadrant: the 900 µm needle was used for 78% of injections administered in the superotemporal quadrant, compared to 65% of the injections in the inferotemporal quadrant.

Figure 3.

Ex vivo endoscopic visualization of SC injection. For endoscopic view setup, enucleated porcine eyes were inflated to an appropriate intraocular pressure by maintaining a 20-cm water column. An aqueous-based green dye was used for easy external visualization. (a) Schematic (image updated from Andrew Meyerson, distributed under a CC-BY-SA-3.0 license) and endoscopic view. (b–d) SC injection visualized externally and internally. (b) Before injection, a smooth, uncompressed inner retinal surface was observed. (c) As pressure was applied from the needle hub to form a dimple externally, a smooth deformation was observed internally. The needle tip, as a sharp point, was not observed. (d) As the SCS was accessed, injectate was immediately observed to flow posteriorly and circumferentially. The black arrowheads highlight the fluid boundary as it expands the SCS.