Comparative Investigation of Seasonal (Summer and Winter) and Sex-Related Differences in Tear Production and Intraocular Pressure in Sakız, Çine Çaparı, and Karya Sheep.

Abstract

OBJECTIVE: This study investigated the seasonal (summer and winter) and sex-related variations in intraocular pressure (IOP) and tear production among Sak&#x131;z, &#xc7;ine &#xc7;apar&#x131;, and Karya sheep reared under similar environmental conditions in the same region. MATERIALS AND METHODS: A total of 180 healthy sheep (30 males and 30 females per breed; Sak&#x131;z, &#xc7;ine &#xc7;apar&#x131;, Karya), ~2&#x2009;years old, were examined. Schirmer tear test (STT-I) and IOP were measured in June (summer; 30&#xb0;C) and January (winter; 10&#xb0;C). Data were analyzed using IBM SPSS Statistics 22 with parametric or non-parametric tests. RESULTS: STT-I values were higher in summer across all breeds (p&#x2009;<&#x2009;0.05). Across breeds, Sak&#x131;z consistently showed greater STT-I than &#xc7;ine &#xc7;apar&#x131; and Karya in both summer and winter. Within-breed seasonal shifts were pronounced for STT-I but small for IOP. Sex effects were generally absent, except in Sak&#x131;z during winter, where females had higher STT-I (17.64&#x2009;&#xb1;&#x2009;3.98 vs. 15.61&#x2009;&#xb1;&#x2009;3.51&#x2009;mm/min) and IOP (18.78&#x2009;&#xb1;&#x2009;4.03 vs. 16.87&#x2009;&#xb1;&#x2009;2.74&#x2009;mmHg) than males (p&#x2009;<&#x2009;0.05). IOP remained stable in most breeds and seasons, and significant differences were confined to specific subgroups, including winter increases in Sak&#x131;z and Karya females, with interbreed IOP variations limited to particular cases such as higher summer values in Karya males. CONCLUSION: Seasonal variation significantly affects tear production, whereas intraocular pressure remains largely stable, with minor sex-related differences observed in some breeds.