IMPORTANCE OF PACHYMETRY IN DIAGNOSIS OF OPEN ANGLE GLAUCOMA

Abstract

Objective: The objective of the study was to establish relation between Central Corneal Thickness (CCT) and Intra-Occular Pressure (IOP) in Open Angle Glaucoma (OAG).

Methods: A prospective study of randomly selected 100 cases was conducted where-in IOP was measured using Goldmann Applanation Tonometer and CCT was measured using Accutone Pachymeter. According to the CCT, patients was grouped into 3 categories: Group A - patients with normal CCT (510-530µm), Group B- patients with low CCT(<510 µm) and Group C -patients with high CCT(>530µm). Patients with history of any condition altering CCT were excluded. The IOP was adjusted using the correction nomogram : Corrected IOP = Applanation IOP + [5 mm Hg(mean normal - measured CCT µm) / 70 µm]. The measured IOP & corrected IOP was compared in each group and the data so obtained was analysed using the non-parametric chi square test.

Result: Based on our findings, p value in group A with normal CCT is 0.9 (not significant), p value in group B with low CCT is 0.05 (significant) & in group C with high CCT is 0.029 (significant). Without the aid of corrected IOP 5 patients in group B having high IOP would have been wrongly labelled as having normal IOP & 9 patients in group C would have been wrongly labelled as having glaucoma.

Conclusion: Thus CCT should be routinely taken into consideration as part of the comprehensive eye exam while measuring IOP, as knowledge of an individual's CCT provides valuable information about the accuracy of IOP status.