Neel D. Pasricha

The composition and volume of tear fluid lining the ocular surface are governed by the rates of lacrimal gland secretion, tear film evaporation, nasolacrimal drainage, and epithelial ion and water transport. Tear fluid hyperosmolality and reduced volume are key drivers of dry eye disease (DED) pathogenesis. We constructed a mathematical model to compute the composition and volume of tear fluid and epithelial cell compartments, with transport parameters specified for the mouse eye based on published data and in vivo measurements of ocular surface potential differences. The model accounted for transcellular and paracellular transport across the epithelia under open-circuit conditions utilizing flux equations for individual transport mechanisms, with mass balance constraints on solute and water content in cytoplasm and tear fluid. Model computations revealed a rough orthogonality between the determinants of tear fluid volume and osmolality in which lacrimal secretion and nasolacrimal drainage primarily regulate tear fluid volume, whereas evaporation and transepithelial osmosis primarily regulate tear fluid osmolality. Under DED conditions established by reduced lacrimal secretion and increased evaporation, the model predicted the efficacy of currently available DED therapies, including punctal plugs, humidification goggles, lacrimal gland stimulation, and artificial tear eye drops. The model also predicted the limited efficacy of anti-absorptive and pro-secretory drugs targeting epithelial ion transporters and the high efficacy of targeting epithelial water permeability or paracellular ion permeability. The modeling herein provided quantitative predictions to prioritize drug targets for DED to drive the development of novel therapies.

To establish a reliable method for isolating and culturing high-purity primary human corneal epithelial cells (HCECs) for ophthalmic drug testing. We present a detailed, step-by-step protocol for the efficient isolation and culture of primary HCECs. This protocol includes the characterization of HCEC morphological responses to varying Ca2+ concentrations in the culture medium. Additionally, immunofluorescence staining with well-established markers is used to identify and confirm the cell types in vitro. A Ca2+ assay is performed to validate the functionality of the cultured primary HCECs. By following the procedures detailed in this protocol, high-purity primary HCECs with strong proliferative capacity and preserved morphological integrity are obtained. Immunofluorescence staining confirms the presence of both limbal stem cells and differentiated corneal epithelial cells in vitro. Additionally, the functional assay demonstrates that the cultured primary HCECs retain the ability to respond to external Ca²⁺ stimuli. This optimized protocol enhances the efficiency and reliability of primary HCECs isolation and culture, enabling the development of a robust in vitro model for studying the mechanisms of ocular diseases. Successfully cultured primary HCECs in vitro bridges the gap between laboratory findings and clinical applications, facilitating advancements in therapeutic development.

Infectious keratitis (IK), including bacterial, fungal, parasitic, and viral etiologies, continues to represent a significant cause of ocular morbidity in the United States and around the world. Corneal scraping for smears and cultures remains the gold standard in diagnosing IK; however, molecular diagnoses, including metagenomic deep sequencing (MDS), are promising emerging diagnostic tools. Despite recent interest in procedural treatment such as riboflavin photoactivated chromophore corneal collagen cross-linking (PACK-CXL) and Rose Bengal photodynamic antimicrobial therapy (RB-PDAT), medical treatment advances have remained stagnant. Methods: This review highlights IK pathogens obtained from corneal cultures at Bascom Palmer Eye Institute (BPEI) from 2011 to 2021 and provides the current BPEI algorithms for initial management of IK or as a referred clinically worsening patient. The roles of corticosteroid therapy, PACK-CXL, and RB-PDAT for IK are also summarized. Results: A total of 9326 corneal cultures were performed at BPEI between 2011 and 2021, and only 3609 (38.7%) had a positive organism identified, of which bacteria were the most common (83.4%). Fortified vancomycin and tobramycin are recommended as first-line medical therapy for IK patients based on culture sensitivity data for the top Gram-negative (Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) bacteria. PACK-CXL and RB-PDAT may benefit IK patients with corneal melting and fungal IK, respectively. Conclusions: Drug holidays, minimizing contamination, and optimizing sample order are crucial to maximizing corneal culture positivity. PACK-CXL and RB-PDAT are promising procedural advancements for IK therapy.

Purpose: The purpose of this study was to report a case of light-adjustable lens (LAL; RxSight, Aliso Viejo, CA) implantation in a patient with bilateral 50-cut radial keratotomy (RK) and discuss related preoperative, intraoperative, and postoperative considerations. Methods: A 78-year-old patient with a history of bilateral 50-cut RK underwent phacoemulsification with implantation of LALs in both eyes 1 month apart. Although LAL technology was not approved specifically for addressing limitations in intraocular lens calculation post-RK due to corneal topography irregularity, the patient opted for this lens due to its ability to make postoperative adjustments to its refractive power. At postoperative month 1 following the second-eye surgery, YAG capsulotomy was performed in both eyes. At postoperative month 2 following the second-eye surgery, the patient began LAL adjustments spaced 1 to 2 weeks apart for a total of 2 LAL adjustments and 2 lock-in sessions. Results: Our patient achieved a final refraction of −0.25 +0.25 × 110 with an UDVA of 20/20-2 in the right eye and −0.25 + 0.50 × 135 with an UDVA 20/25-1 in the left eye. Conclusions: The LAL may be a promising option for patients undergoing cataract surgery after RK, although further studies are needed to understand long-term changes in eyes with RK and the inability of LAL to address all aspects of corneal aberration.

Purpose of Review: This study is to highlight the incidence of corneal pseudomicrocysts in FDA-approved antibody–drug conjugates (ADCs), and success of preventive therapies for pseudomicrocysts and related ocular surface adverse events (AEs). Recent Findings: ADCs are an emerging class of selective cancer therapies that consist of a potent cytotoxin connected to a monoclonal antibody (mAb) that targets antigens expressed on malignant cells. Currently, there are 11 FDA-approved ADCs with over 164 in clinical trials. Various AEs have been attributed to ADCs, including ocular surface AEs (keratitis/keratopathy, dry eye, conjunctivitis, blurred vision, corneal pseudomicrocysts). While the severity and prevalence of ADC-induced ocular surface AEs are well reported, the reporting of corneal pseudomicrocysts is limited, complicating the development of therapies to prevent or treat ADC-related ocular surface toxicity. Summary: Three of 11 FDA-approved ADCs have been implicated with corneal pseudomicrocysts, with incidence ranging from 41 to 100% of patients. Of the six ADCs that reported ocular surface AEs, only three had ocular substudies to investigate the benefit of preventive therapies including topical steroids, vasoconstrictors, and preservative-free lubricants. Current preventive therapies demonstrate limited efficacy at mitigating pseudomicrocysts and other ocular surface AEs.

Keratoconus is a disorder characterized by progressive corneal thinning and steepening that may result in significant visual impairment secondary to high astigmatism, corneal scarring, or even corneal perforation. Early detection and screening of keratoconus are essential for effective management and treatment. Several screening methods, such as corneal topography and tomography, corneal biomechanics, and genetic testing, are being developed to detect keratoconus at an early stage. Once detected, prevention of progression is the mainstay of keratoconus management. Corneal collagen cross-linking is a minimally invasive treatment option that can slow or halt the progression of keratoconus. Additionally, recent studies have investigated the potential use of copper sulfate eye drops (IVMED-80) and extracellular vesicles to prevent the progression of keratoconus as non-invasive treatment options. For visual rehabilitation, currently available treatments include scleral lenses, intracorneal ring segments, corneal allogenic intrastromal ring segments, and deep anterior lamellar keratoplasty. The safety and efficacy of these emerging treatment options for keratoconus are currently being investigated.

Purpose of Review: To review the role of ocular surface epithelial (corneal and conjunctival) ion transporters in the pathogenesis and treatment of dry eye disease (DED). Recent Findings: Currently, anti-inflammatory agents are the mainstay of DED treatment, though there are several agents in development that target ion transport proteins on the ocular surface, acting by pro-secretory or anti-absorptive mechanisms to increase the tear fluid film volume. Activation or inhibition of selected ion transporters can alter tear fluid osmolality, driving water transport onto the ocular surface via osmosis. Several ion transporters have been proposed as potential therapeutic targets for DED, including the cystic fibrosis transmembrane conductance regulator (CFTR), calcium-activated chloride channels (CaCCs), and the epithelial sodium channel (ENaC). Summary: Ocular surface epithelial cell ion transporters are promising targets for pro-secretory and anti-absorptive therapies of DED.