The study was done to propose and validate a new pterygium grading system based on slit-lamp evaluation.

217 patients with pterygium were included. All patients underwent slit-lamp examination, and slit-lamp photographs were independently graded by two graders twice.

868 independent assessments, based on 217 slit-lamp images, were performed by two graders. For conjunctival assessment, the intra-rater reliability was excellent for body thickness (κ=0.81–0.89) and size at limbus (κ=0.87–0.92), substantial-to-excellent for body vascularity (κ=0.72–0.86), and moderate-to-excellent for body length (κ=0.57–0.81), whereas the inter-rater reliability was excellent for size at limbus (κ=0.86), substantial for body thickness (κ=0.72–0.73) and body vascularity (κ=0.66–0.75), and moderate for body length (κ=0.54–0.57). The grading system was named SLIT2, which included Stocker’s line, Size at limbus, Length of head/body, Injection/vascularity of body/head, and Thickness of body/head.

The study concluded that the proposed SLIT2 grading system, consisting of eight components, may serve as a reliable tool to standardise the reporting of pterygium severity and disease recurrence for clinical and research applications.