The CGAL gonioscopic contact glass was designed by Roussel and Fankhauser for laser treatments of the chamber angle. It is made of mineral glass and is antireflection coated. It reduces the laser spot by a factor of 1.5 as compared to a Goldmann lens. Lower energies are therefore required for treatment with the YAG laser. Thanks to its magnifying effect, the CGAL contact glass also improves aiming accuracy and success rate in laser trabeculoplasty.
In office examination, the CGAL contact glass allows the visualization of the fine structures of the trabeculum with high resolution and produces brilliant photographs and video recording due to the low reflectivity coating in the visible spectral region and unique optical design.