This article is more than 5 years old. Information may no longer be current.
Intraocular tonometry shows safe IOP levels with femtosecond laser
German researcher is the first to apply this technique during corneal applanation in a living human eye.
Click Here to Manage Email Alerts
Intraocular needle tonometry applied to a human eye showed that IOP remains within safe limits when the IntraLase femtosecond laser is used for a treatment.
“IOP increases for a short time during the application of the suction ring, but also at its highest peak, it remains below 110 mm Hg and returns immediately to normal values as the suction ring is released,” said H. Burkhard Dick, MD, of the Ruhr University Eye Clinic in Bochum, Germany.
Until now, IOP variations during LASIK using the IntraLase (Abbott Medical Optics) vs. a mechanical microkeratome were only tested in porcine eyes by applying a transducer connected to the anterior chamber. The IntraLase had already shown in these experiments to produce a smaller increase of pressure.
IOP measurements
Dr. Dick was the first researcher to test these changes in a living human eye. The patient was a 59-year-old man who was scheduled for enucleation in April 2008 because of a small iris tumor with bronchial malignant metastasis. IOP was measured using intraocular needle tonometry with the Düsseldorf device G-19235 by Geuder. The needle was directly placed in the anterior chamber through the suction ring.
“A series of IOP measurements were taken dynamically, before, during and after application of the suction ring. The setting, procedure and IOP measurements were video recorded by two professional photographers,” Dr. Dick told Ocular Surgery News.
Variations
Currently, intraocular needle tonometry is the only way of measuring in vivo IOP variations, Dr. Dick said. Needle tonometry also revealed reproducible IOP values during corneal applanation with the IntraLase. IOP increased during application of the ring, remained less than 100 mm Hg for all measurements and returned to normal after suction ring release.
Although there might be some intraindividual variation, this experience shows that there should be no fear of increased IOP during femtosecond laser procedures, and this most probably applies to both IntraLase-assisted keratoplasty procedures and, presumably, flap performance in LASIK, Dr. Dick said. – by Michela Cimberle
- H. Burkhard Dick, MD, can be reached at Universität-Augenklinik, Bochum, In der Schornau 23-25, 44892 Bochum, Germany; +49-234-299-3100; fax +49-234-299-3109; e-mail: burkhard.dick@kk-bochum.de.