The Influence of Central Corneal Thickness on The Intraocular Pressure as Measured by Different Tonometers: Non-Contact Tonometer and Goldmann Applanation Tonometer

Abstract

Background and objectives: Intraocular pressure plays a crucial role in maintaining vision and preventing eye disease. Beyond its importance in diagnosing and managing glaucoma, intraocular pressure measurements significantly impact the evaluation of postoperative outcomes, complications and optimize patient recovery. This study quantifies the influence of central corneal thickness on intraocular pressure using both Goldmann applanation tonometer and non-contact tonometer.

Methods: In a prospective clinical trial, the subjects were recruited from glaucoma unit at Shahid Dr. Aso Eye Hospital in Sulaimania city/Iraq between January and June 2023. Intraocular pressure measurements were conducted in a randomized sequence for both eyes using both Goldmann applanation tonometry and non-contact tonometry exploring the correlation between measured inter-tonometer discrepancies employing linear regression analysis with central corneal thickness.

Results:  The study included 200 eyes of 100 consecutive patients diagnosed with either ocular hypertension or glaucoma. Mean age was 56.8 years, male (55%) and female (45%). Mean central corneal thickness was 533 ± 42 mm and mean intra ocular pressure were 14.9 ± 4.3 mm Hg, 19.3 ± 5.4 mm Hg for Goldmann applanation tonometry and non-contact tonometry, respectively. There is a statistically significant relationship between central corneal thickness and intraocular pressure by Goldmann applanation tonometry (r2 = 0.1, p 0.001) and non-contact tonometry (r² = 0.17, p 0.001).

Conclusion:  Both Goldmann applanation tonometry and non-contact tonometry are influenced by central corneal thickness. However, non-contact tonometry was significantly more sensitive to central corneal thickness variations compared to Goldmann applanation tonometry.