Abstract
Purpose :
To test the influence of fluorescein instillation and Goldmann’s Applanation Tonometry (GAT) on the Corvis ST (Oculus; Wetzlar, Germany) measurement.
Methods :
In this prospective, cross-sectional observational study, 92 healthy eyes from 46 patients with no ocular pathology with age ranging from 17 and 60 years old were evaluated. Exclusion criteria included ocular hypertension, glaucoma, history of any ocular surgery or inflammation, and distance corrected visual acuity worse than 20/40. Every eye was first examined by the Corvis ST. Then, after instillation of fluorescein and topical anesthetic, GAT was accomplished and after that, the eye was again measured by Corvis ST. 126 variables derived from the Corvis ST were evaluated using paired statistical tests accordingly to the distribution of each parameter (T-Test and Wilcoxon signed-rank).
Results :
One eye randomly selected from each of the 46 patients was included. From the 126 variables derived from the Corvis, only 8 (6%) variables had statistically significant (p<0,05). The measurements of intraocular pressure with TAG indicated Mean Deviation (MD) of 14.0 mmHg. The Corvis ST showed IOPnct (uncorrected intraocular pressure) MD before and after fluorescein was 15.2 mmHg and 14.7 mmHg, respectively, and bIOP (biomechanically corrected intraocular pressure) MD was 13.7 mmHg and 13.9 mmHg, respectively.
The biomechanical analysis of the Scheimpflug images showed that there was an increase in the corneal thickness after the use of fluorescein, besides the confirmation of the following variables with statistical significance: applanation 2 Length, Pressure Pic Diff, Density Increase Applanation 1 and 2, Density Increase Max, Densito Increase Highest Concavity and Greyval Cornea.
Conclusions :
The instillation of fluorescein and the performance of GAT has a minor influence on intraocular pressure measurements by Corvis ST. There are some parameters that were affected, including corneal thickness which impact deserves future analysis.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.