Purpose <p>To investigate whether nasal anatomical alterations associated with nasal septum deviation (NSD) contribute to early functional impairment in the lacrimal drainage system, potentially indicating subclinical stages of primary acquired nasolacrimal duct obstruction (PANDO).</p> Methods <p>Sixty-nine patients with unilateral NSD were included. Individuals with clinical or radiological evidence of PANDO were excluded. Lower tear meniscus height (LTMH) and area (LTMA) were bilaterally measured using anterior segment optical coherence tomography (AS-OCT). Nasal anatomical parameters were assessed on both the deviation side (DS) and contralateral side (CS) using paranasal sinus computed tomography (PNS-CT).</p> Results <p>Both LTMH and LTMA were significantly higher on the DS compared to the CS (p &lt; 0.001). Significant positive correlations were observed between DS-LTMH and LTMA and several nasal anatomical features, including concha nasalis inferior bone thickness (CNI-BT), attachment angle, CNI–maxillary sinus angle (CNI-MS), CNI length, and inferior nasal meatus volume (INMV) (p &lt; 0.05). On the CS, no nasal anatomical parameter demonstrated a significant correlation with both LTMH and LTMA.</p> Conclusion <p>NSD may impair tear drainage even in the absence of clinical signs of PANDO. The observed correlations between tear meniscus parameters and specific nasal anatomical structures suggest that sinonasal alterations secondary to NSD may contribute to subclinical tear stasis. These findings highlight the potential role of nasal anatomy as an early indicator of predisposition to nasolacrimal duct obstruction in asymptomatic individuals.</p>