COMPARISON OF INTRAOCULAR PRESSURE IN SPARGUE-DAWLEY RATS USING TWO TYPES OF TONOMETERS

The present study was designed to compare intraocular pressure (IOP) values by two types of tonometers in condition of normotensive and glaucomatous rat model. Glaucomatous eyes were induced by intracameral injections of hyaluronic acid in right eyes of six-week-old male Spargue-Dawley (SD) rats. Normotensive contralateral eyes were left eyes of the SD rats. IOP was measured using a rebound tonometer (Tonolab) and an immersive tonometer (Tonopen® XL) about 3:00 pm. The mean IOP values of normotensive control eyes were 10.80 ± 1.03 mmHg by Tonopen, and 15.10 ± 0.73 mmHg by Tonolab which were statistically insignificant (p = 0.1). The mean IOP values of glaucomatous experimental eyes were 30.20 ± 2.67 mmHg by Tonopen, and 37.90 ± 2.73 mmHg by Tonolab which were statistically insignificant (p = 0.95). High IOP values of glaucomatous eyes by two types of tonometers had strong positive correlation with each other (r = 0.904, p <0.01). There was a decrease of ganglion cell layer cells in retina of glaucomatous eye compared to that of normotensive eye. This is the first study to compare IOP values using two types of tonometers between normotensive and glaucomatous model made by intracameral injection of hyaluronic acid. It can be concluded that Tonopen should be used carefully when the IOP is within normal range, and both Tonopen and Tonolab can be used reliably when the IOP is high.