Authors:
Dr Pablo Rodrigues* 1
, Dr Bernardo Moscovici 1
, Dr Renato Ambrosio Jr 2
, Dr Mauro Campos 1
, Dr Walton Nose 1
1Unifesp,Sao Paulo,Brazil, 2Rio de Janeiro Corneal Tomography and Biomechanics Study Group,Rio de Janeiro,Brazil
Purpose
To investigate the reversibility of tomographic and biomechanical screening abnormalities induced by primary pterygium using Scheimpflug tomography and dynamic corneal response analysis.
Setting
Spot Clinic, São Paulo, Brazil
Methods
Prospective observational study including 25 eyes of 25 patients with primary nasal pterygium extending ≥2.0 mm onto the cornea. Pentacam HR and Corvis ST were performed preoperatively and 3 months after excision with conjunctival autografting. Tomographic parameters (Kmax, astigmatism, BAD-D, and topographic keratoconus classification [TKC]) and Corvis outcomes (deformation amplitude, peak distance, Corvis Biomechanical Index [CBI], Tomographic and Biomechanical Index [TBI], DA Ratio, Integrated Radius, Ambrosio Relational Thickness [ARTh], stiffness parameter at first applanation [SP-A1], and stress–strain index [SSI]) were compared using paired analyses.
Results
Kmax decreased from 45.78 ± 1.92 to 44.96 ± 1.88 D (p < 0.001), corneal astigmatism from 2.56 ± 0.92 to 1.89 ± 0.85 D (p < 0.001), and BAD-D from 2.89 ± 0.54 to 2.17 ± 0.48 (p < 0.001). Forty percent of eyes were classified as TKC ≥1 preoperatively, and all eyes were classified as TKC 0 postoperatively. Deformation amplitude decreased (1.18 ± 0.10 to 1.13 ± 0.09 mm; p = 0.014), and peak distance increased (4.08 ± 0.25 to 4.21 ± 0.28 mm; p = 0.041). Both composite screening indices declined (CBI: 0.31 ± 0.12 to 0.27 ± 0.10; p = 0.048; TBI: 0.42 ± 0.15 to 0.34 ± 0.13; p = 0.011).
DA Ratio, Integrated Radius, ARTh, SP-A1, and SSI showed no significant changes (SSI: 1.39 ± 0.34 to 1.32 ± 0.32; p = 0.96).
Conclusions
Primary pterygium induces reversible alterations in tomographic and biomechanical screening that may mimic keratoconus-like patterns, particularly in artificial intelligence–based indices such as the TBI. Surgical excision leads to significant improvement in corneal tomography and normalization of composite ectasia screening indices, while parameters related to intrinsic corneal stiffness remain stable. These findings suggest that the observed preoperative abnormalities are primarily driven by anterior surface distortion rather than true biomechanical weakening. Post-excisional reassessment is essential to improve the accuracy of ectasia screening and clinical decision-making, especially in candidates for refractive or cataract surgery.