Ocular residual astigmatism (ORA) does not seem to correlate with baseline refractive error among refractive surgery candidates

• Published in: International ophthalmology Vol. 43; no. 11; pp. 4087 - 4096
• Main Authors: Balparda, Kepa, Silva-Quintero, Laura Andrea, Acevedo-Urrego, Andrea, Herrera-Chalarca, Tatiana
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-11-2023; Springer Nature B.V
• Subjects: Astigmatism; Axl protein; Chi-square test; Cornea; Correlation; Eye surgery; Medicine; Medicine & Public Health; Myopia; Ophthalmology; Original Paper; Population studies; Subtraction; Surgery; Variance analysis; Vector analysis; Corneal-based laser surgery; Baseline refractive error; Ocular residual astigmatism; Refractive surgery
• ISSN: 1573-2630; 0165-5701; 1573-2630
• DOI: 10.1007/s10792-023-02826-8

Purpose
Ocular residual astigmatism (ORA) is defined as the difference between refractive astigmatism and anterior corneal astigmatism. A high ORA may be correlated with poorer results in patients undergoing corneal-based laser surgery. Is a high baseline refractive error related to a higher degree of ORA?
Methods
This was a retrospective analytical study including 181 right eyes of an equal number of refractive surgery candidates. Manifest subjective refraction was measured, along with a Pentacam AXL Wave corneal tomography. Via a vector analysis with this methodology, subjective cylinder was translated into the corneal plane and a vectorial subtraction was performed in order to measure ORA. Spearman’s rank order test, one-way ANOVA and Chi-square were used to determine whether different levels of baseline refractive error correlate with different levels of ORA.
Results
Mean age was 28.33 ± 4.71 years with a female preponderance (65.7%). Mean ORA was 0.74 ± 0.39 D, with 33.1% of eyes having an ORA ≥ 0.90 D. There was not a correlation between ORA and level of myopia (rho = − 0.022;
p
 = 0.764), nor between ORA and spherical equivalent (rho = 0.009;
p
 = 0.903). Refractive astigmatism did not demonstrate to be correlated with ORA level either (rho = 0.078;
p
 = 0.329). One-way ANOVA tests failed to demonstrate an association between different classifications of refractive error and level of ORA.
Conclusions
In the studied population, ORA is not correlated with baseline refractive error. Every patient presenting for possible corneal-based laser refractive surgery should be evaluated for a possible high level of ORA, irrespective of their baseline ametropia level.