Corneal Damage from Infrared Radiation
Abstract
This report summarizes research on corneal damage from exposures to multiple pulses of CO(2) laser radiation at 10.6 (micrometer) and Tm: YAG laser radiation at 2.02 (micrometer). Retinal damage from sources with rectangular irradiance distributions was also modeled. Thresholds for CO(2) exposures were determined for sequences of up to 1024 pulses (80 ns duration) at frequencies of 10 and 16 Hz. Thresholds for Tm: YAG exposures were determined sequences of up to 128 pulses (0.300 5 duration) at 1 Hz, and for sequences of up to 999 pulses at 10 and 20 Hz (0.025 5 duration) and 100 Hz (0.005 5 duration). Thresholds are correlated by an empirical power law relationship between either the energy density per pulse (CO(2) or the irradiance (Tm:YAG) and the number of pulses. For some Tm: YAG exposures the law underestimates the damage threshold for small numbers of pulses. Thresholds for single pulses of Tm: YAG radiation and multiple pulses of CO(2) radiation also are described by a critical temperature model. A critical temperature model sometimes, but not always, describes threshold damage from sequences of pulses of Tm: YAG radiation. Predicted retinal damage thresholds for rectangular irradiance distributions were compared to those for Gaussian beams having equal lie areas. Agreement was excellent for beams with low aspect ratios; but only fair for beams with high aspect ratios where the effects of lateral heat conduction become more important at longer exposures.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2000
- Accession Number
- ADA380426
Entities
People
- C. B. Bargeron
- Russell L. Mccally
Organizations
- Johns Hopkins University