Long term positional stability of the Argus II retinal prosthesis epiretinal implant.

BACKGROUND: The Argus II Retinal Prosthesis System (Second Sight Medical Products, Sylmar, California) is an epiretinal prosthesis that serves to provide useful vision to people who are affected by retinal degenerative diseases such as retinitis pigmentosa (RP). The purpose of this study was to analyze postoperative movement of the electrode array. METHODS: Five patients diagnosed with profound retinal dystrophy who have undergone implantation of retinal prosthesis at Stony Brook University Hospital. Fundoscopy was performed at postoperative month 1 (M1), month 3 (M3), month 6 (M6), month 12 (M12), and month 24 (M24) visits. Fundoscopy was extracted and analyzed via NIH ImageJ. Data analysis was completed using IBM SPSS. Various lengths and angles were measured each postoperative month using ImageJ. RESULTS: There was no significant change in distance between the optic disc and the surgical handle (length AB) over the two-year span (F = 0.196, p = 0.705). There was a significant change in distance of length AB over time between patients between M3 and M6 (p = 0.025). A repeated measures ANOVA revealed that there was statistically significant change of the optic disc-tack-surgical handle angle (𝛾) (M1 to M24) (F = 3.527, p = 0.030). There was no significant change in angle 𝜟 (the angle to the horizontal of the image), angle 𝜶 (tack-optic disc-surgical handle), and angle 𝜷 (optic-disc-surgical handle-tack). CONCLUSION: Our results demonstrate that there may be postoperative movement of the retinal prosthesis over time, as a statistically significant downward rotation is reported over the 2 years span. It is important, moving forward, to further study this movement and to take into consideration such movement when designing retinal implants. It is important to note that this study is limited by the small sample size, and therefore, the conclusions drawn are limited.

Bilateral microsporidial keratoconjunctivitis in a clinically healthy female receiving intravitreal steroid injections: Associations and potential risk factors.

Purpose: To present a unique case of bilateral microsporidial keratoconjunctivitis in a clinically healthy female receiving intravitreal steroid injections, and explore several associations and potential risk factors. Observations: A 75-year-old woman with chronic idiopathic anterior uveitis was receiving regular intravitreal steroid in both eyes for secondary cystoid macular edema. Flare-ups of iritis were usually treated with topical non-steroidal anti-inflammatory drops, but in the left eye the patient also received a few limited courses of topical corticosteroid. The patient regularly instilled topical cyclosporine 0.05% for dry eyes. She was otherwise clinically healthy but had low serum Immunoglobulin (Ig) M levels. There was no history of trauma or exposure to contamination. In her course of treatment, she developed a bilateral punctate keratitis. Corneal scrapings were diagnostic of Microsporidia. Topical voriconazole and moxifloxacin, as well as corneal debridement, were effective in resolving the infection. Conclusions and importance: We propose that the factors and associations described in this case--intravitreal steroid, topical steroid, topical cyclosporine, and IgM deficiency--contributed variably to create relative, local, immunologic suppression in our patient. Among these potential risk factors, we believe that intravitreal steroid exposure may be prominent. In aggregate, they facilitated development of her opportunistic microsporidial corneal infection. Eye care specialists should have a high index of suspicion for microsporidial keratitis, if they observe an atypical chronic punctate keratitis in patients with similar clinical associations.

Development of 3D Printed Electrospun Scaffolds for the Fabrication of Porous Scaffolds for Vascular Applications.

Over the past two decades, electrospinning has emerged as a common technique to produce biomedical scaffolds composed of ultrafine fibers formed from many natural and synthetic polymers. A major advantage of this technique is the ability to produce scaffolds that resemble the native extracellular matrix in physical, chemical, and topological properties. However, scaffolds fabricated via electrospinning are not formed with a controlled architecture and typically do a poor job of directing cell growth into prescribed structures for tissue/organ development. To address these weaknesses, 3D bioprinting has recently been used to develop scaffolds that have a highly organized and precise global topology. Unfortunately, these 3D bioprinted scaffolds do not typically resemble the native extracellular matrix in physical properties, such as porosity, fiber diameter, and pore size (e.g., the microarchitecture). Thus, the goal of the current study was to develop a technique that harnesses the intrinsic advantages of both conventional electrospinning and 3D bioprinting techniques to produce scaffolds that have the potential to be used within biomedical applications. The physical properties of formed 3D printed electrospun scaffolds were compared with conventional electrospun and 3D printed scaffolds. Further, we conducted initial proof-of-concept biocompatibility studies to illustrate the applicability of the scaffolds within vascular applications. Our results illustrate that 3D printed electrospun scaffolds can be developed, via our technique, that have highly tailored and organized arbitrary geometries with scaffold properties in the range of the innate extracellular matrix. In addition, these scaffolds were shown to support endothelial cell growth. Therefore, we illustrate the development and testing of a novel bioscaffold fabrication technique that may be used for many tissue engineering and regenerative medicine applications, which allows for the direct printing of electrospun scaffolds into well-defined macro-scale geometries that also retain the micro-structures commonly observed in electrospun scaffolds.