LASIK-induced Changes on Central Corneal Thickness and Intraocular Pressure in Enucleated Porcine Globes
Feltgen N., Müller A., Funk J.
Dept. of Ophthalmology, Freiburg University
Purpose: The intraocular pressure (IOP) in LASIK-treated eyes is lower as compared to preopertive values. We were interested if this difference is caused by changes in the central corneal thicknes (CCT).
Method: 80 freshly enucleated porcine globes were grouped as follows: group I: LASIK treated (n=20); group II: flap without LASIK (n=20); group III: control (n=40). In all eyes two different levels of IOP were measured (a: 10 and b: 18 mmHg). LASIK was performed by an excimer laser (193 nm). We tried to ablate between 100 and 211 µm of corneal tissue. The flap was cut with the Hansatome microkeratome. Before and after treatment the IOP was measured directly with an intraocular device and applanatory with the Tonopen and the Perkins tonometer. CCT was determined with an ultrasonic pachymeter. All eyes were examined histologically.
Results: Measurement with the Perkins tonometer often failed. Agreement between tonopen and directly measured IOP was very high in the controls (group III) and high in the flap eyes (group II). After LASIK the difference of IOP values (dL) between tonopen and direct measurement increased. At the level (a) dL was 0.8 mmHg, at the level (b) dL was 3,05 mmHg.
Conclusions: 1) Perkins measurement often failed in LASIK treated enucleated porcine eyes. However, we found an agreement between tonopen and directly measured IOP. In human eyes tonopen coul
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