Congenital Nasolacrimal Duct Obstruction (CNLDO)

In children, Congenital Nasolacrimal Duct Obstruction (CNLDO) is a condition characterized by obstruction of the nasolacrimal duct drainage system which leads to epiphora or over-tearing. At Protheragen we provide extensive services for the diagnostics and therapeutics for CNLDO.

Overview of Congenital Nasolacrimal Duct Obstruction (CNLDO)

Congenital Nasolacrimal Duct Obstruction (CNLDO) is a paediatric nasolacrimal duct blockage disorder that causes excessive tearing with a possibility of mucous discharge. It usually results from obstructions located at the distal end of the nasolacrimal duct caused by a persistent membrane, bone deformities, or stenosis of the inferior meatus. Globally, CNLDO affects around 5% to 20% of infants and is more prevalent in premature infants.

Fig.1 Schematic representation of the right nasolacrimal duct. (Sasaki T., et al., 2024)

The CNLDO mechanism originates from obstruction which is distally situated in the nasolacrimal duct (NLD) at the Hasner valve. While most CNLDO cases spontaneously resolve in the first year of life, some patients face prolonged obstruction which could lead to distress in both children and parents.

Diagnostics Development for Congenital Nasolacrimal Duct Obstruction

Fluorescein Dye Disappearance Test (FDT)

The FDT is a non-invasive diagnostic method that measures the clearance of fluorescein dye from the tear meniscus. It possesses a sensitivity of 90% and a specificity of 100%, which makes it superior for the confirmation of lacrimal duct obstruction. The test employs a drop of fluorescein dye placed in the conjunctival sac and measures the time needed for the dye to disappear. Prolonged time needed for the dye to disappear is indicative of CNLDO.

Therapeutics Development for Congenital Nasolacrimal Duct Obstruction

Our Services

At Protheragen, we take pride in our comprehensive suite of services dedicated to advancing diagnostics and therapeutics of congenital nasolacrimal duct obstruction.

CNLDO Target Identification and Validation Services

Protheragen supports the discovery and mechanistic validation of novel therapeutic targets for CNLDO using multi‑omic profiling, spatial transcriptomics, and functional genomics in human CNLDO patient‑derived tissues and isogenic in vitro systems. Services include whole‑transcriptome sequencing (RNA‑seq) of obstructed nasolacrimal duct mucosa, proteomic analysis of tear fluid from CNLDO infants, and bioinformatic prioritization of druggable targets linked to epithelial canalization, extracellular matrix remodeling, and mucosal inflammation.

Functional validation is performed via CRISPR‑Cas9 gene editing, RNA interference (RNAi), and overexpression studies in primary human nasolacrimal duct epithelial cells (HNLDECs) cultured under physiologically relevant air–liquid interface (ALI) conditions. Protheragen quantifies target‑dependent changes in barrier function, mucin secretion, inflammatory cytokine release (IL‑6, TNF‑α, TGF‑β), and fibrotic marker expression (collagen I, fibronectin, α‑SMA) to establish causal links between target modulation and CNLDO‑relevant phenotypes. These data enable clients to select high‑confidence targets and generate mechanistic rationale for lead optimization.

In Vitro CNLDO Model Development and High‑Throughput Screening (HTS) Services

Protheragen develops and validates human‑relevant in vitro models of CNLDO that replicate key pathological features, including membranous obstruction, epithelial dysfunction, inflammatory activation, and subepithelial fibrosis. Model systems include:

• Primary human nasolacrimal duct epithelial cell (HNLDEC) cultures: ALI cultures that mimic the mucosal barrier and secretory function of the native duct.
• CNLDO‑mimetic membrane models: 3D extracellular matrix (ECM) constructs containing a persistent membranous barrier to assess drug‑induced perforation and remodeling.
• Lacrimal sac‑nasolacrimal duct organoids: 3D self‑assembling structures that recapitulate tissue architecture, luminal formation, and inflammatory responses.
• Lacrimal drainage microfluidic chips: Organ‑on‑chip systems that simulate tear flow, pressure dynamics, and mucosal–luminal interactions for real‑time efficacy monitoring.

Ex Vivo CNLDO Tissue Efficacy and Mechanism Studies

To bridge in vitro findings to in vivo physiology, Protheragen offers ex vivo testing in freshly harvested animal and human‑donated lacrimal drainage tissues. Tissues are maintained in specialized organ culture systems that preserve viability, mucosal structure, and inflammatory responsiveness for up to 72 hours, allowing clinically relevant exposure to test articles via topical application or luminal perfusion—mimicking intended clinical administration routes.

Services include ex vivo assessment of:

• Drug penetration into nasolacrimal duct mucosa and submucosa.
• Changes in tissue patency, membrane thickness, and collagen density via histomorphometry and confocal microscopy.
• Modulation of key signaling pathways (e.g., TGF‑β/Smad, MAPK, NF‑κB) driving fibrosis and inflammation.
• Mucosal healing and re‑epithelialization kinetics following therapeutic intervention.

Protheragen's ex vivo platform generates mechanistic data on target engagement, pharmacodynamic response, and tissue‑level efficacy without animal use, supporting early candidate prioritization and reducing later‑stage attrition.

Ocular PK/PD and Local Tolerability Assessment Services

For topically administered CNLDO therapies—eye drops, gels, inserts, or nasal sprays—Protheragen provides specialized ocular pharmacokinetic (PK) and pharmacodynamic (PD) profiling tailored to the pediatric lacrimal system. Studies quantify drug concentration–time profiles in tear fluid, conjunctiva, lacrimal sac, nasolacrimal duct mucosa, and adjacent nasal tissues using validated LC‑MS/MS and bioanalytical methods.

PD assessments link drug exposure to biological response, including:

• Reduction in inflammatory cytokine levels in lacrimal fluid.
• Downregulation of fibrotic gene and protein expression in ductal mucosa.
• Improvement in mucosal barrier function and epithelial integrity.
• Enhancement of luminal patency in CNLDO‑mimetic models.

CNLDO Therapy Formulation and Delivery Optimization Services

Successful CNLDO pharmacotherapy requires formulations that maximize retention in the lacrimal sac, penetrate the obstructed ductal membrane, and provide sustained local exposure while minimizing systemic exposure—especially in infants. Protheragen offers formulation design and optimization services for pediatric‑friendly CNLDO dosage forms, including:

• Low‑irritation, preservative‑free topical solutions and suspensions.
• Mucoadhesive gels and in situ gelling systems for extended lacrimal retention.
• Nanoparticle and liposomal carriers for enhanced mucosal penetration.
• pH‑adjusted and isotonic formulations compatible with infant ocular and nasal tissues.

Translational Biomarker Development and Qualification Services

Protheragen identifies, validates, and qualifies non‑invasive translational biomarkers for CNLDO to enable objective efficacy assessment in preclinical and clinical studies. Biomarker categories include:

• Tear‑based biomarkers: Cytokines (IL‑1β, IL‑6, TGF‑β2), matrix metalloproteinases (MMP‑3, MMP‑9), and mucins (MUC5AC) measured by multiplex bead arrays and ELISA.
• Imaging biomarkers: Ductal diameter, membrane thickness, and patency rate quantified via micro‑OCT and high‑resolution microscopy.
• Molecular biomarkers: Mucosal gene expression signatures of inflammation, fibrosis, and epithelial remodeling measured by qPCR and RNA in situ hybridization.

Preclinical Safety and Toxicology Profiling Services

Protheragen delivers comprehensive safety assessment services for CNLDO therapies, focused on local ocular and nasal toxicology relevant to pediatric populations. Studies include acute and repeated‑dose local tolerance, ocular surface irritation, corneal endothelial safety, nasal mucosal histopathology, and potential for systemic absorption. Assessments follow OECD and ICH S4 guidelines with study designs adapted to the immature ocular and nasal tissues of infant models.

Additional safety services include in vitro ocular irritancy testing (HET‑CAM, reconstructed human corneal epithelium models), cytotoxicity in primary nasolacrimal duct cells, and off‑target pharmacology screening to identify potential safety liabilities early in development. Protheragen's toxicology team integrates all safety endpoints into a unified report that supports clinical risk assessment and phase 1 trial design.

Diagnostics Development

• Karyotype Analysis Service
• Omics Analysis Service
• Biomarker Development Service
• Artificial Intelligence Service
• Customized Diagnostics Development

Therapeutic Development

• Small Molecule Drug
• Cell Therapy
• Gene Therapy
• Therapeutic Antibody
• Therapeutic Peptide
• Therapeutic Protein
• Customized Therapy Development

Disease Models

• Surgical Mouse Models
• Prickle1 Mutant Mouse Models
• Self-Curing Resin Induced NLDO Rabbit Models
• Bacterial Injection Rabbit Models

We provide a range of preclinical research services to support the development of CNLDO diagnostics and therapeutics. Our services include:

• Animal Model Development: We develop and validate animal models of CNLDO to study the pathogenesis and test new therapeutic interventions.
• In Vitro Studies: We conduct in vitro studies to investigate the cellular and molecular mechanisms underlying CNLDO and to screen potential therapeutic compounds.
• Pharmacokinetics and Toxicology Studies: We perform comprehensive safety and pharmacokinetics testing of new diagnostics and therapeutics in preclinical models to ensure their safety and effectiveness before human trials.

If you are interested in our services, please feel free to contact us.

References

• Sasaki, Tsugihisa, et al. "Congenital nasolacrimal duct obstruction: clinical guideline." Japanese Journal of Ophthalmology 68.4 (2024): 367-388.
• Vagge, Aldo, et al. "Congenital nasolacrimal duct obstruction (CNLDO): a review." Diseases 6.4 (2018): 96.
• Takahashi, Yasuhiro, et al. "Management of congenital nasolacrimal duct obstruction." Acta ophthalmologica 88.5 (2010): 506-513.