Vet Ophthalmol. 2026 Mar;29(2):e70159. doi: 10.1111/vop.70159.
ABSTRACT
OBJECTIVE: This study investigated the seasonal (summer and winter) and sex-related variations in intraocular pressure (IOP) and tear production among Sakız, Çine Çaparı, 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; Sakız, Çine Çaparı, Karya), ~2 years old, were examined. Schirmer tear test (STT-I) and IOP were measured in June (summer; 30°C) and January (winter; 10°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 < 0.05). Across breeds, Sakız consistently showed greater STT-I than Çine Çaparı 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 Sakız during winter, where females had higher STT-I (17.64 ± 3.98 vs. 15.61 ± 3.51 mm/min) and IOP (18.78 ± 4.03 vs. 16.87 ± 2.74 mmHg) than males (p < 0.05). IOP remained stable in most breeds and seasons, and significant differences were confined to specific subgroups, including winter increases in Sakız 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.
PMID:41823045 | DOI:10.1111/vop.70159
