A retrospective study of the correlation of intraocular pressure and ultrasound biomicroscopy parameters with cataract maturity in small breed dogs

There is a clinical challenge in decision-making regarding prophylactic glaucoma treatment based solely on intraocular pressure (IOP) trends for long-term cataract management or before phacoemulsification surgery in canines. This study aimed to compare IOP and ultrasound biomicroscopy (UBM) parameters with cataract maturity in small dog breeds. We conducted a retrospective review of medical records pertaining to ophthalmic examinations and UBM assessments of small breed dogs diagnosed with cataracts at the Veterinary Medical Teaching Hospital of Seoul National University from January 2020 to August 2024. UBM images obtained under topical anesthesia were analyzed to quantify various parameters. Subsequently, the 47 eyes examined were classified into four groups according to cataract maturity. The ciliary cleft area (CCA), ciliary cleft length (CCL) and width (CCW), and iridocorneal angle (ICA) were measured. The measured values were compared to determine their degree of correlation with cataract maturity. Statistical analyses of patient demographics were also performed. Both CCA (P=0.0024) and CCL (P=0.0004) decreased significantly with increasing cataract maturity. However, IOP, CCW, and ICA were not significantly associated with cataract maturity. Age and sex did not have significant effects on any dependent variable. Among the UBM parameters, CCA and CCL demonstrated a significant correlation with cataract maturity, indicating structural alterations in the ICA might develop in association with cataracts, independent of direct IOP effects. These findings underscore the importance of considering prophylactic glaucoma management in patients with advanced cataracts to mitigate potential complications.