['Recent studies have examined the effects of intranasal corticosteroids (INSs) in relieving the ocular symptoms of seasonal allergic rhinoconjunctivitis (SAR) and perennial allergic rhinitis. However, because most of these studies were based on subjective assessments by patients, the associated factors and mechanism of action are unknown.', 'A single-center, randomized, double-blind, parallel-group study was carried out in which patients with SAR were randomly assigned to an INS mometasone furoate nasal spray (MFNS) group or to a placebo group and treated once daily for 4 weeks. Substance P concentrations in tears were measured, ocular and nasal symptoms were recorded by patients in an allergy diary, and findings were recorded by an ophthalmologist.', 'There was no significant difference between treatment groups in the mean change from baseline of substance P concentration in tears after 4 weeks of treatment, but the mean change tended to increase in the placebo group and tended to decrease in the MFNS group (P = 0.089). All ocular and nasal symptom scores, except eye tearing, were significantly lower in the MFNS group than in the placebo group. Furthermore, substance P concentrations were strongly correlated with ocular and nasal symptom scores.'] Does mometasone furoate nasal spray relieve the ocular symptoms of seasonal allergic rhinoconjunctivitis?