The correlation between myopia severity and stress-strain index (SSI) using the Corneal Visualization Scheimpflug...

Area of Science:

• Ophthalmology
• Biomechanical Engineering
• Optometry

Background:

• Myopia, a prevalent refractive error, is associated with changes in ocular biomechanics.
• Corneal biomechanical properties, assessed using devices like the Corneal Visualization Scheimpflug Technology (Corvis ST), are increasingly recognized for their role in ocular health.
• The stress-strain index (SSI) is a key parameter derived from Corvis ST, reflecting corneal stiffness.

Purpose of the Study:

• To investigate the correlation between myopia severity and the stress-strain index (SSI).
• To compare dynamic corneal response and stiffness parameters between different myopia severity groups.
• To analyze the relationship between SSI and various ocular parameters, including axial length (AL), spherical equivalent refraction (SER), and corneal curvature.

Main Methods:

• Subjects were categorized into two groups based on AL and SER: 22-26.00 mm AL with SER < -6.00D, and ≥26.00 mm AL with SER > -6.00D.
• Corvis ST was used to measure dynamic corneal response and stiffness parameters, including SSI.
• Statistical analyses were performed to compare groups and assess correlations between SSI and ocular parameters (AL, SER, age, AL/CR, AL-ACD).

Main Results:

• Significant differences in SSI were observed between the two myopia groups (P < 0.01).
• In the high myopia group (≥26.00 mm AL), SSI showed a weak negative correlation with AL (r = -0.265, P < 0.01), AL/CR (r = -0.376, P < 0.01), and AL-ACD (r = -0.224, P < 0.01), and a weak positive correlation with SER (r = 0.251, P < 0.01).
• No significant correlation between SSI and AL, AL-ACD, AL/CR, or SER was found in the moderate myopia group (22-26.00 mm AL).

Conclusions:

• SSI is significantly correlated with axial length in eyes with high myopia (≥26.00 mm AL).
• This correlation is independent of corneal curvature and anterior chamber depth.
• The findings suggest that corneal biomechanical properties, as indicated by SSI, are altered in high myopia and are primarily influenced by axial elongation.