JOURNAL OF EVIDENCE BASED MEDICINE AND HEALTHCARE

Table of Contents

2018 Month : February Volume : 5 Issue : 6 Page : 531-536

COMPARISON OF INTRAOCULAR PRESSURE MEASUREMENT WITH NON-CONTACT TONOMETRY AND APPLANATION TONOMETRY AMONG VARIOUS CENTRAL CORNEAL THICKNESS GROUPS

Radhakrishnan B1, Hemapriya S2, Nazeem Farzana Ghouse3, Aparna Rajagopalan4

Corresponding Author:
Dr. Hemapriya S,
#B1, Geetanjali apartments, 282,
Avvai Shanmugam Road (Lloyd's Road),
Gopalapuram, Chennai- 600086.
E-mail: hemapriya.siva@gmail.com
DOI: 10.18410/jebmh/2018/108

ABSTRACT
BACKGROUND
Glaucoma is the second leading cause of blindness worldwide. Intraocular Pressure (IOP) is the only known modifiable risk factor that has been shown to delay progression in both ocular hypertension and glaucoma patients. Clinical measurement of IOP has undergone several technical advances from the initial digital tension measurements, through indentation tonometry, to applanation tonometry and non-contact tonometry. This study was done to compare the intraocular pressure (IOP) measurements with Non Contact Tonometry (NCT) and Goldmann Applanation tonometry (GAT) and to compare NCT IOP and GAT IOP among various central corneal thickness (CCT) groups.

MATERIALS AND METHODS
IOP measurements were done by NCT and then by GAT followed by CCT. All IOP readings were taken in the sitting position over fifteen minutes. NCT was performed before the GAT to avoid the known mild reduction of IOP by anterior chamber compression with GAT.

RESULTS
The study included 200 eyes of 100 patients. Mean age of the patients was 58.14 ± 11.7 years (range 35- 81 years). The study population consisted of 58 males and 42 females. The mean ± SD intraocular pressure measurements were 23.39 ± 4.6 mmHg and 22.41 ± 5.9 mmHg for NCT and GAT, respectively. The difference between the NCT and GAT IOP was 0.98 ± 4.7 mm Hg. Mean CCT of the study group was 545.74 ± 38.23 microns. The IOP measured with both GAT and NCT showed no significant change with increasing CCT. The difference between the means increases with increasing CCT upto 600 microns. At lower IOPs ≤ 20 mm Hg, GAT measures are higher than NCT and this relationship is reversed at high IOPs.

CONCLUSION
Intraocular pressure measurement by NCT was consistently higher than GAT. There was a tendency for NCT to underestimate IOP at lower ranges and overestimates IOP at higher ranges. By applying appropriate correction factor for CCT, Noncontact tonometry could be used as a good screening tool for glaucoma evaluation.

KEYWORDS
Non- Contact Tonometer, Applanation Tonometry, Central Corneal Thickness, IOP, Glaucoma.