Purpose:The purpose of this case series is to evaluate the use of spectral domain optical coherence tomography (SD-OCT) imaging in equine corneal disease to demonstrate the feasibility, diagnostic effectiveness, and limitations of this imaging modality. Methods: Retrospective study: Handheld SD-OCT (Envisu, Bioptigen Inc, Morrisville, NC) was used for high-resolution imaging of horses with corneal disease presenting to the North Carolina State University Equine Ophthalmology Service from 2013 to 2018. Results: Fourteen horses were included in this study, including six horses with corneal ulceration, three with stromal abscesses (SA), three with immune-mediated keratitis (IMMK), and two with ocular neoplasms. High-resolution images of the cornea were obtained using handheld SD-OCT in standing horses; however, acquiring images was time-consuming due to the inherent movement of the examiner and horse. Despite this, in horses with corneal ulcers, SA, and IMMK, SD-OCT assisted with determining location of disease in the cornea (eg, superficial, mid-stromal, endothelial) and if disruption of Descemet's membrane was present. In horses with neoplasia, the SD-OCT helped to determine whether the cornea had neoplastic invasion from anterior chamber masses. Conclusions: Results from this retrospective study suggest that handheld SD-OCT for imaging the cornea of horses is feasible and may be helpful in determining depth and extent of lesions in the cornea.

Purpose: Drug delivery directly to the corneal stroma currently relies on microscopic injections that demonstrate low reproducibility and clinician-dependent variability. With use of biological drugs such as adeno-associated viral (AAV) vectors, precise and consistent drug deposition is critical to reduce concerns related to off-target transduction and the host's immune response to the viral capsid and/or transgene-derived product. Therefore, a precise corneal injection (PCI) microneedle was designed to allow accurate depth-specific injections into the corneal stroma in a macroscopic setting. Methods: High-frequency ultrasound and confocal microscopy demonstrated the consistent ability to predetermine the precise injection depth using PCI needles of varying sizes. Next, a comparison between a standard 31-G needle and PCI needles was performed in vivo using AAV vector gene delivery. Results: Intrastromal corneal injections using the PCI microneedle resulted in less vector leakage at the site of injection and fewer anterior chamber penetrations compared with a standard 31-G needle. Although reporter gene expression appeared similar when the vector was administered with either needle type, a trend toward increased vector genomes was noted in the PCI-injected corneas at the experimental conclusion. As hypothesized, corneal perforation resulted in increased detection of AAV vector genomes in nontarget tissues, highlighting the importance of consistency for biological drug applications in the cornea. Conclusions: Further development of the PCI microneedle is warranted especially for AAV corneal gene therapy and offers the potential to enhance transduction while significantly reducing safety concerns and intraclinician and interclinician injection variability.

The influenza virus is the causative agent of the flu, a contagious respiratory illness that causes morbidity, loss of productivity, and, in some instances, death. Although the seasonal flu is typically only life threatening to high‐risk groups, exceptionally virulent forms of the virus that emerge during pandemics, can even threaten strong and otherwise healthy individuals. A strong arsenal of antiviral drugs is essential during a pandemic, but drug resistance threatens our preparedness. A key target for antivirals is neuraminidase, an enzyme that cleaves glycosidic bonds between sialic acid residues on cell surface glycoproteins so that the virus can infect or escape from host cells to repeat the cycle of infection. The enzyme exists as a homo‐tetramer with calcium ions stabilizing the protein structure. Antiviral medications, including Oseltamivir and Zanamivir, inhibit neuraminidase activity but resistance to Oseltamivir is most prevalent. The challenges posed by the rapid evolution of drug resistance have led Dr. Schiffer and her colleagues to develop more innovative ways, based on structural analyses to formulate drugs that are immune to resistance. We chose to focus on resistance of the His274Tyr neuraminidase mutant to the drug Oseltamivir using the crystal structure solved by Collins and colleagues that demonstrates that this resistance is due to a shift in the position of Glu276 into the hydrophobic pocket of the active site. Using the software application, Jmol, we designed physical models based on the overlaid crystal structures of the wild type and the His274Tyr mutant to visualize the shift in Glu276 and its impact on binding of each of three potential ligands: Oseltamivir, Zanamivir, and Sialic Acid. In addition, the catalytic residues Tyr406 and Glu277 were displayed to visualize the lack of impact on catalytic cleavage of the natural substrate, but continued inhibition by Zanamivir. By designing a physical model of Neuraminidase to emphasize the dimensional and catalytic residues, a better understanding of the protein’s function and potential inhibition by drugs can be obtained and may lead to a more effective way to design drugs in the future. Support or Funding Information Support for the CREST Project is through NSF‐IUSE #1725940.

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