Corneal-tissue absorption coefficients for 193- and 213-nm ultraviolet radiation

Area of Science:

• Ophthalmology
• Biomedical Optics
• Laser-Tissue Interaction

Background:

• Understanding corneal optical properties is crucial for laser-based ophthalmic procedures.
• Accurate measurement of absorption coefficients is essential for predicting laser energy deposition.
• Previous studies may lack precise measurements at specific ultraviolet wavelengths relevant to excimer lasers.

Purpose of the Study:

• To determine the small-signal absorption coefficients of bovine corneal tissue.
• To investigate the optical properties of the cornea at 193 nm and 213 nm using nanosecond laser pulses.
• To establish a foundation for understanding corneal response to ultraviolet laser irradiation.

Main Methods:

• Measured absolute reflectance at a quartz-cornea interface using varying angles of incidence.
• Employed low-intensity laser irradiation, significantly below the ablation threshold.
• Utilized Fresnel theory to analyze reflectance data and estimate the complex index of refraction.

Main Results:

• Estimated corneal absorption coefficient at 193 nm: 39,900 ± 9800 cm⁻¹.
• Estimated corneal absorption coefficient at 213 nm: 21,400 ± 4900 cm⁻¹.
• Demonstrated high absorption of ultraviolet laser light by corneal tissue.

Conclusions:

• Bovine corneal tissue exhibits substantial absorption of 193-nm and 213-nm nanosecond laser pulses.
• The determined absorption coefficients provide critical data for modeling laser-cornea interactions.
• These findings are vital for the safety and efficacy of ultraviolet laser applications in ophthalmology.