Color vision deficits and laser eyewear protection for soft tissue laser applications

Purpose: Laser safety considerations require urologists to wear laser eye p rotection. Laser eye protection devices block transmittance of specific lig ht wavelengths and may distort color perception. We tested whether urologis ts risk color confusion when wearing laser eye protection devices for laser soft tissue applications. Materials and Methods: Subjects were tested with the Farnsworth-Munsell 100 -Hue Test without (controls) and with laser eye protection devices for carb on dioxide, potassium titanyl phosphate (KTP), neodymium (Nd):YAG and holmi um:YAG lasers. Color deficits were characterized by error scores, polar gra phs, confusion angles, confusion index, scatter index and color axes. Laser eye protection device spectral transmittance was tested with spectrophotom etry. Results: Mean total error scores plus or minus standard deviation were 13 /- 5 for controls, and 44 +/- 31 for carbon dioxide, 273 +/- 26 for KTP, 22 +/- 6 for Nd:YAG and 14 +/- 8 for holmium:YAG devices (p <0.001). The KTP laser eye protection polar graphs, and confusion and scatter indexes reveal ed moderate blue-yellow and red-green color confusion. Color axes indicated no significant deficits for controls, or carbon dioxide, Nd:YAG or holmium :YAG laser eye protection in any subject compared to blue-yellow color visi on deficits in 8 of 8 tested with KTP laser eye protection (p <0.001). Spec trophotometry demonstrated that light was blocked with laser eye protection devices for carbon dioxide less than 380, holmium:YAG greater than 850, Nd :YAG less than 350 and greater than 950, and KTP less than 550 and greater than 750 nm. Conclusions: The laser eye protection device for KTP causes significant blu e-yellow and red-green color confusion. Laser eye protection devices for ca rbon dioxide, holmium:YAG and Nd:YAG cause no significant color confusion c ompared to controls. The differences are explained by laser eye protection spectrophotometry characteristics and visual physiology.