Study Of The Effect Of Corneal Rigidity On Intraocular Pressure Indicators With Different Types Of Tonometry

Cornea is a marker of changes in the biomechanical behavior of the eye. A number of studies show that the biomechanics of the cornea changes in patients with myopia and depends on the degree of myopia. There is evidence of changes in the biomechanics of the cornea in patients with diabetes, in patients who use local anti-glaucoma eye drops, in patients with keratoconus, in patients with age-related macular degeneration and glaucoma. For a long time, the measurement of the biomechanical properties of the eye was mainly carried out with the help of invasive means, manometric devices and paired Schiotz tonometry. Domestic research opens up new opportunities for determining the condition of the cornea in various clinical situations.

The aim of our study was to determine the influence of corneal rigidity on intraocular pressure indicators with different types of tonometry in patients with emmetropia and myopia of varying degrees.

194 patients (372 eyes) with emmetropia (60 eyes) and myopic refraction of various degrees (312 eyes) participated in the study. The average age of the patients was 25+2 years. Among the examined were 95 men (48.97%) and 99 women (51.03%). Determination of intraocular pressure (IOP) with different types of tonometry was carried out in accordance with the principles of randomization by independent, experienced doctors. Determination of biomechanical properties, the coefficient of corneal rigidity (K_ER), was carried out using the method of assessing the corneal rigidity (Sergienko MM, Shargorodska IV, 2008). IOP was calculated taking into account the K_ER – IOP(k) and the correction factor taking into account the K_ER – k.

The analysis of the results indicated the influence of CCT on tonometry indicators when determining IOP in emmetropic eyes by the Maklakov tonometry method (r=0.532,p<0.05), ricochet tonometry (r=0.334, p<0.05) and especially Pneumotonometry (r=0.611,p<0.05). The smallest effect of CCT on tonometry indicators was determined by Goldman tonometry (r=0.186,p<0.05). The results indicated the absence of a correlation between the K_ER in emmetropic eyes and CCT, the independence of this indicator from the level of IOP, which was confirmed by the determination of IOP by various methods, and the effect of CCC on K_ER. IOP measurement taking into account the K_ER and determining the k based on it was the most accurate for all types of tonometry.

As a result of the conducted research, it was established that determining the biomechanical properties of the cornea is of great importance for accurate measurement of the level of intraocular pressure. A more effective technique is the intravital determination of the coefficient of corneal rigidity and its consideration as a correction when determining the calculated IOP in emmetropic eyes and eyes with various degrees of myopia.