Purpose <p>To identify clinical characteristics and risk factors associated with corneal guttae in Japanese patients undergoing cataract surgery and to examine the relationship between guttae severity and anterior segment parameters.</p> Study design <p>This retrospective observational study analyzed 410 eyes from 410 patients who underwent cataract surgery between April 2021 and March 2023.</p> Methods <p>Corneal guttae were evaluated using specular microscopy and graded according to the modified Reykjavik Eye Study classification (Grades 0–4). Demographics, corneal endothelial characteristics, and ocular biometric parameters were assessed. Univariate and multivariate logistic regression analyses were performed to identify risk factors for corneal guttae.</p> Results <p>Corneal guttae were present in 23.2% of patients (Grade 1: 17.1%, Grade 2: 4.9%, Grade 3: 0.7%, Grade 4: 0.5%). Multivariate analysis identified female gender (OR=1.81, 95% CI: 1.04–3.14, p=0.036), shallower anterior chamber depth (OR=0.47, 95% CI: 0.23–0.98, p=0.043), corneal endothelial cell density (per 100 cells/mm²) (OR=0.84, 95% CI: 0.74–0.94, p=0.003), and higher spherical equivalent refractive error (OR=1.25, 95% CI: 1.12–1.41, p&lt;0.001) as significantly associated factors. Most parameters showed significant trends across severity grades. Endothelial characteristics including cell density, coefficient of variation, and hexagonality demonstrated significant relationships (all p&lt;0.001), along with more pronounced hyperopia with increasing guttae severity (p-trend&lt;0.001).</p> Conclusions <p>Female gender, shallow anterior chamber, low endothelial cell density, and hyperopic refractive error are independently associated with corneal guttae in Japanese cataract patients. Progressive changes across severity grades suggest that anatomical factors contribute to endothelial vulnerability. These findings enhance the understanding of guttae pathophysiology and improve preoperative risk assessment.</p>