The Use of an Off Axis Slit Laser Camera System for Determining Photodisruptive Laser Placement in Lenses

Abstract

Purpose:: Determining lens shape and A/P is important for accurate placement of photodisruptive patterns in the lens. The purpose of this study was to investigate the use of an off axis slit laser camera system to guide the placement of a photodisruptive laser in various lenses.

Methods:: A 780nm slit laser was made incident on aplanated porcine and rabbit eyes at approximately 30 degrees with respect to the normal. This laser was then scanned across the aplanated eye while images of the illuminated cross section were collected using an off axis camera system. The off axis camera system was at an angle of approximately 25 degrees with respect to the normal of the incident plane of the aplanator. The camera was stopped down so that the aplanated anterior segment and the lens were in focus. After images were captured, the imagery was used to determine the placement of a photodisruptive laser pattern in the eye. The eye was then treated using a photodisruptive laser . The accuracy of the placement laser was then determined through the use of micrography and ultrasound.

Results:: Although the lens is an age dependent gradient structure having a unknown varying index of refraction, it was found that the slit laser camera system was accurate for effective placement of the photodisruptive laser. Based on ultrasound imaging measurements (E-Technologies MHF-1) the slit laser camera system was able to place the photodissruption laser treatment patterns to within 100 microns of the desired location within the lens.

Conclusions:: The off axis slit laser camera system allows for accurate placement of photodisruptive laser treatment patterns within the lens.

Keywords: presbyopia • laser • refractive surgery: other technologies