Effect Of Controlled External Corneal Compression On Corneal Tomography, Pachymetry, And Biomechanics In Healthy Eyes: A Prospective Crossover Study

Published 2026 - 44th Congress of the ESCRS

Reference: POOTH038 | Type: Free paper | DOI: 10.82333/yxys-0e97

Authors: Dr John Warrak* ¹ , Dr Yehya Tlaiss ¹ , A/Prof. Elias Warrak ¹

¹Ophthalmology,University of Balamand,Beirut,Lebanon

Purpose

To quantify the immediate and short-term effects of standardized external corneal compression on corneal tomography, pachymetry, and biomechanical parameters in healthy, non-operated eyes.

Setting

Ophthalmology Department, MLH / Advanced Eye Care Center (AEC).

Methods

This prospective, controlled, single-blind, within-subject crossover study enrolled healthy adult volunteers (18–45 years) with no prior ocular surgery and normal corneal topography. External compression was applied over closed lids using a calibrated Honan balloon at 10, 20, and 30 mmHg for 10 minutes per level in randomized order.

Pentacam tomography, full pachymetry mapping, Corvis ST biomechanical assessment, and intraocular pressure (IOP) measurements were obtained at baseline, immediately post-compression (T0), and at 5, 15, and 30 minutes.

Primary outcomes were change in central corneal thickness (ΔCCT) and change in Corvis deformation amplitude (ΔDA) at T0.

Results

Preliminary analysis demonstrates pressure-dependent, transient reductions in central corneal thickness and measurable alterations in corneal deformation amplitude immediately after compression. Higher compression levels were associated with greater ΔCCT and ΔDA. Most parameters returned to baseline within 15–30 minutes. Baseline corneal thickness and stiffness indices were predictive of susceptibility to biomechanical change.

Conclusions

Controlled external compression induces measurable, dose-dependent, and reversible alterations in corneal thickness and biomechanical behavior in healthy eyes. These findings have implications for preoperative preparation (e.g., Honan balloon use), interpretation of tomography and biomechanics, and potential transient risk in borderline corneas.