First studies on presbyopia treatment using ultra short laser pulses
03/03/2003

The Laser Zentrum Hannover e.V. (LZH) has carried out first studies on the treatment of presbyopia using ultra-short laser pulses. Experiments have been carried out on both pig and rabbit eyes, and have shown that this method is promising for the treatment of presbyopia.

Presbyopia (Greek for "old eye") is due to a loss of flexibility in the lens. It becomes stiffer with age, and the ciliary muscles can no longer exactly control its shape. Thus, the lens partially loses its ability to focus light correctly on the retina. And accordingly, almost every middle-aged person needs glasses to read a newspaper, magazine, or book.

Elasticity could be regained by making small cuts inside the lens, loosening the hard tis-sue structures and simultaneously reducing tissue density, making it easier for the ciliary muscles to shape the lens correctly. Since both the cornea and the lens transmit near-infrared light, it is possible to focus a Titanium-Sapphire femtosecond-laser directly into the lens. Exact cutting in the micrometer range is possible, without causing damage to the rest of the eye.

Basically, two different cut patterns inside the lens have proven to be beneficial. One is a planar pattern with up to four rings. A second cutting pattern uses three-dimensional star-like shapes, The inner and outer diameter as well as the number of stripes and their depth can be varied.

Experiments on ex-vivo pig eyes showed that the ring pattern could be cut without diffi-culties, using the given parameters. Star-like cuts in both ex-vivo and in-vivo rabbit eyes were also possible. A low energy level of 1 µJ was chosen, to prevent unwanted side effects, such as bubbles. The focus spot was approximately 5 µm in diameter. These first experiments showed neither haze nor damage in the eye or lens. Although further research is still necessary, ultrashort laser pulses momentarily seem to be a very promising tool for treatment of presbyopia.

Press release for download: 
Business Development & Communications Department
Michael Botts
Public Relations
Tel.: +49 511 2788-151
Fax: +49 511 2788-100
The Laser Zentrum Hannover e.V. (LZH) carries out research and development in the field of laser technology and is supported by the Ministry of Economic Affairs, Labour and Transport of the State of Lower Saxony (Niedersächsisches Ministerium für Wirtschaft, Arbeit und Verkehr).