Posters

Statistical evaluation of the effect of corneal thickness, corneal curvature and axial length on the tonometric intraocular pressure (IOP) of myopic eyes

Poster Details

First Author: A.Kachanov RUSSIA

Co Author(s):    S. Bauer   V. Kornikov   B. Zimin              

Abstract Details

Purpose:

To estimate the impact of some ocular parameters (central corneal thickness /CCT/, corneal curvature /Kavg/, and axial length /AL/) on tonometric intraocular pressure (IOP) of myopic eyes by using statistical analysis.

Setting:

1 – St.-Petersburg branch of Sv. Fyodorov “Eye Microsurgery Clinic”, 2 – North-Western State Medical University named after I.I. Mechnikov, ³ – Saint-Petersburg State University, ⁴ – Baltic Technical University; 1 - 4 – St.-Petersburg, Russia.

Methods:

We performed a statistical analysis (STATISTICA 7) of clinical pre-op data of 193 patients (385 eyes) examined and further operated on by the LASIK technology (MEL-80, “Carl Zeiss Meditec”) for the laser correction of low, moderate and high myopia. In this work we consider the results of measurements of tonometric IOP with two different tonometers – Maklakov’s tonometer (M-IOP) and noncontact pneumotonometer (TOPCON) (P-IOP).The correlation coefficient r between Maklakov’s IOP (M-IOP) and CCT is equal to 0.39, and between pneumotonometer’s IOP (P-IOP) and CCT r is equals to 0.60. Both are statistically significant at the level = 0.001.

Results:

A statistically significant inverse relationship (r=-0.26) was found between M-IOP and axial length AL (p 0.01). No dependence (r=0.02) was found for P-IOP and AL at a significance level of 0.05 (p 0.05). The correlation coefficient r between corneal curvature (Kavg) and M-IOP r = -0.306 – the inverse relationship between them is statistically significant (p 0.001). The correlation coefficient between corneal curvature (Kavg) and P-IOP is r = 0.07, which indicates the absence of a statistically significant relationship (p 0.1).

Conclusions:

A statistically significant direct correlation between tonometric intraocular pressure (IOP) and central corneal thickness (CCT) is higher for pneumotonometry. But Maklakov’s tonometer readings are more affected by the corneal curvature (Kavg) and the axial length (AL) of the eye then by CCT, whilst pneumotonometer’s measurements are not correlated with the corneal curvature (Kavg) and the axial length (AL) of the eye.

Financial Disclosure:

None