Corneal curvature gradient map: A new corneal topography map to predict the corneal healing process

PURPOSE: To evaluate a new curvature gradient topography map to predict postoperative corneal remodeling. METHODS: In this retrospective study, 32 eyes of 16 patients with myopia underwent excimer ablation surgery with a postoperative high curvature gradient. The new curvature gradient map (acquired immediately postoperatively) shows the difference between the curvatures of two points over the distance between them; it was compared to the tangential curvature difference map between 1 and 12 months postoperatively to determine their relationship. Corneas were divided into 12 regions for analysis: four 90°-wide sectors centered on 0° , 90° , 180° , and 270°. There were three subdivisions in each sector: central (radius: 0 to 2.75 mm), paracentral (radius: 2.75 to 3.25 mm), and peripheral (radius: 3.25 to 4.5 mm). Linear regression analysis was performed by region. RESULTS: The following regions had significant relationships between the initial curvature gradient and curvature difference between 1 and 12 months postoperatively: the paracentral zone of the 90° sector (P = .0145; R² = 0.1832) and both the central (P = .0034; R² = 0.2522) and paracentral (P = .0452; R ² = 0.1271) zones of the 270° sector. The greatest average initial tangential curvature was in the 270° sector. CONCLUSIONS: The initial curvature gradient after surgery predicted change in tangential curvature over the subsequent 12 months in areas where initial tangential curvature was greatest. When the curvature gradient was high, the surface curvature modification remained in progress months after surgery.