Proposal for a Novel Severity Grading System for Pterygia Based on Corneal Topographic Data

Area of Science:

• Ophthalmology
• Corneal topography
• Vision science

Background:

• Pterygium, a common eye condition, can cause visual impairment.
• Assessing pterygium severity often relies on subjective clinical grading.
• Objective measures of corneal irregularity are needed to complement existing assessments.

Purpose of the Study:

• To introduce a novel grading system for pterygium severity using corneal higher-order irregularity (HOI).
• To assess the effectiveness of this grading system in evaluating postoperative changes in corneal irregularity.
• To correlate pterygium grade with preoperative visual acuity and corneal surface regularity.

Main Methods:

• Corneal topography data from 268 eyes with primary nasal pterygium were analyzed before and up to 6 months after surgery.
• Fourier harmonic analysis was used to quantify HOI components within specific corneal diameters.
• A 4-level grading system (0-3) was developed based on threshold increases in HOI, with associations to surface regularity index (SRI), irregular components (IRR), and best-corrected visual acuity (BCVA) examined.

Main Results:

• The proposed grading system included 62 (grade 0), 65 (grade 1), 41 (grade 2), and 100 (grade 3) eyes.
• Preoperative SRI, IRR, and BCVA significantly varied across the grades, with grade 3 showing the highest SRI.
• Postoperatively, grade 3 pterygia demonstrated significant changes in SRI and IRR between 1 and 6 months, unlike other grades.

Conclusions:

• The developed grading system effectively classifies pterygium severity based on objective corneal topographic data.
• The system allows for the evaluation of postoperative restoration of corneal irregularity.
• Corneal topographic analysis provides an objective method for assessing pterygium severity.