Comparison of Tono-Pen AVIA Intraocular Pressure Measurements Performed at Limbus With Central Corneal Tono-Pen AVIA Intraocular Pressure

Purpose: To compare Tono-Pen AVIA (TPA) intraocular pressure (IOP) measurements performed at the limbus with central corneal Tono-Pen AVIA (TPA) intraocular pressure. Methods: Fifty-one patients attending our outpatient department with a best corrected visual acuity of >= 20/40, no corneal disease, and no astigmatism greater than 1.5 diopters underwent routine ophthalmological examination. Patients with ametropia greater than or equal to +/- 5 diopters, a history of recent contact lens wear, and central corneal thickness of <480 mu m or >550 mu m were excluded from the study. IOP was recorded first in the corneal center, followed by tonometry measurements obtained from the temporal, nasal, superior, and inferior limbus using TPA. IOP measurements were compared using the paired t test. Correlation was derived by Pearson correlation coefficient, and regression equations were derived. Results: The mean age of patients in our study was 43.86 +/- 15.39 years. The mean TPA IOP from the central cornea was 16.59 +/- 3.75 mm Hg. There was a statistically significant difference between Tono-Pen IOP from the central cornea and that recorded from all 4 limbal positions (P < 0.001). There was a positive correlation between the central and the limbal IOP obtained with Tono-Pen. Correlation was maximum for the temporal limbus. Conclusions: Limbal TPA IOP is significantly higher than central TPA IOP. There remains a good correlation between central and limbal IOP. This was found to be greatest for the temporal limbus.