In vivo real-time intraocular pressure variations during LASIK flap creation

To monitor and compare in vivo real-time intraocular pressure (IOP) in rabbit eyes undergoing LASIK flap creation using microkeratome and femtosecond laser.

Thirteen rabbit eyes in each group underwent LASIK flap creation using a microkeratome and a femtosecond laser. In vivo real-time IOP profile was measured using a 30-gauge needle with an IOP catheter sensor inserted into the anterior chamber from the limbus during surgery.

In vivo real-time IOP monitoring was achieved in all cases, showing IOP variations during different phases of LASIK flap creation from docking of the instrument, start of surgery to the end of procedure, and monitoring the post-LASIK stabilization. IOP fluctuations were significantly lower in corneal flaps made with the femtosecond laser than with the microkeratome during globe suction (81.78+/-10.55 vs. 122.51+/-16.95 mm Hg), cutting (62.25+/-3.28 vs. 141.02+/-20.46 mm Hg), and suction (41.40+/-2.99 vs. 89.30+/-12.15). In contrast, femtosecond laser requires double the time (19+/-2 vs. 10+/-2 seconds for globe suction and 19+/-2 vs. 9+/-2 seconds for cutting) for completion of the procedure.

The authors describe an accurate and reliable setup to measure and record in vivo real-time changes in IOP measurement from the anterior chamber during laser surgery. Femtosecond laser flap creation exerts less extreme IOP fluctuations with improved chamber stability but requires more procedure time than does microkeratome.