Identification of a Horizontal Invasion Length Threshold Predicting Posterior Corneal Flattening after Pterygium Excision

Pterygium excision leads to significant posterior corneal flattening proportional to HIL, with 3.5 mm identified as a clinically relevant cutoff. Although the refractive impact may be subtle, surgeons should be aware of these posterior corneal changes as a consistent morphological response, especially in eyes with HIL ≥ 3.5 mm.