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Proposal and validation of a new grading system for pterygium (SLIT2)
  1. Darren Shu Jeng Ting1,2,
  2. Yu-Chi Liu2,3,
  3. Moushmi Patil2,
  4. Angel Jung Se Ji2,
  5. Xiao Ling Fang2,4,
  6. Yih Chung Tham2,
  7. Yi-Fang Lee5,
  8. Hla M Htoon2,
  9. Jodhbir S. Mehta2,3
  1. 1 Academic Ophthalmology, University of Nottingham, Nottingham, UK
  2. 2 Singapore Eye Research Institute, Singapore, Singapore
  3. 3 Cornea And Ext Disease, Singapore National Eye Centre, Singapore, Singapore
  4. 4 Department of Ophthalmology, Shanghai Eye Diseases Prevention and Treatment Center, Shanghai, China
  5. 5 Ophthalmology, Singapore National Eye Centre, Singapore, Singapore
  1. Correspondence to Jodhbir Mehta, Singapore National Eye Centre, 11 Third Hospital Avenue, Singapore, Singapore; jodmehta{at}


Background/aims To propose and validate a new pterygium grading system based on slit-lamp evaluation.

Methods This prospective cross-sectional study included 217 patients with pterygium. All patients underwent slit-lamp examination, and slit-lamp photographs were independently graded by two graders twice. A total of eight parameters were evaluated and all parameters were assigned with a score of 1–4 (normal–severe). Intra-rater and inter-rater reliability as determined by weighted Cohen’s kappa analysis.

Results A total of 868 independent assessment, 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). For corneal assessment, the intra-rater reliability was excellent for all four parameters (κ=0.84–0.90) whereas the inter-rater reliability was excellent for head length (κ=0.86–0.87), substantial-to-excellent for head vascularity (κ=0.78–0.82), substantial for Stocker’s line (κ=0.79–0.80) and head thickness (κ=0.67–0.69). The grading system was named SLIT2, which included S tocker’s line, S ize at limbus, L ength of head/body, I njection/vascularity of body/head, and T hickness of body/head.

Conclusion 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.

  • Conjunctiva
  • Cornea
  • Degeneration
  • Ocular surface
  • Pathology

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  • Contributors Design and conceptualisation of study: YCL and JM. Data collection: DSJT, YCL, MP, AJSJ, XLF, YCT and YFL. Data analysis and interpretation: DSJT, YCL, HMH and JM. Manuscript drafting: DSJT. Critical appraisal and final approval of manuscript: DSJT, YCL, MP, AJSJ, XLF, YCT, YFL, HMH and JM.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement All data relevant to the study are included in the article or uploaded as supplementary information.

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