Abstract
Purpose :
Prior studies relating corneal astigmatism with Goldman applanation tonometry (GAT) are relatively small, and rely on out of date technologies. We performed a prospective study investigating the effect of corneal astigmatism on GAT as measured in the vertical and horizontal meridians (GAT-V and GAT-H, respectively).
Methods :
One-hundred and fifty-four eyes of seventy-seven patients were enrolled in a prospective clinic-based study of routine patients of the Rush Eye Center during the years 2022-2023. Patients were excluded if they had any of the following: diseased cornea or trabecular meshwork, recent ocular surgery, asymmetric lens status or eyedrop medication use. For each patient enrolled, intraocular pressure measurements (IOPcc and IOPg) were obtained using the ocular response analyzer (ORA), as well as independently obtained by an ophthalmologist via manual Goldmann applanation tonometry. Applanation tonometry was performed twice, once with the tip oriented in each the vertical and horizontal meridians. Corneal measurements included anterior, posterior and total keratometry measurements from the IOL Master 700, as well as SimK values reported by the Zeiss Atlas 9000 Corneal Topographer. These values were expressed as a power vector (M, J0, J45) in the manner described by Thibos, where the J0 vector represents the Jackson Cross cylinder with the plus cylindrical axis at 90 degrees.
Results :
There was a positive and statistically significant association between IOPcc with Goldmann Applanation tonometry measured in each the vertical (GAT-V: r = 0.723, p = 0.0059) and horizontal (GAT-H: r = 0.698, p=0.0068) meridians. A similar relationship was found with IOPg and Goldmann applanation tonometry (GAT-V: r= 0.720, p=0.006 and GAT-G: r=0.681, p=0.008). There was no statistically significant association of GAT-V or GAT-H with any of the corneal topographic indices.
Conclusions :
Goldmann applanation tonometry measured in each of the vertical and horizontal meridians correlates well with IOPc and IOPg as measured on the Ocular Response Analyzer, suggesting reliability of the applanation data. There is no noted association between measured corneal astigmatism and applanation pressure, regardless of the axis of astigmatism or axis of Goldmann applanation tonometry.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.