Accession Number : ADA334135

Title :   Corneal Damage from Infrared Radiation.

Descriptive Note : Annual rept. 1 Nov 96-31 Oct 97

Corporate Author : JOHNS HOPKINS UNIV LAUREL MD

Personal Author(s) : McCally, Russel L.

PDF Url : ADA334135

Report Date : DEC 1997

Pagination or Media Count : 24

Abstract : This report summarizes our research during the past year on the interaction of 80 ns pulses of infrared radiation produced by a CO2-TEA laser with the cornea. Epithelial damage thresholds were determined for sequences of 1, 2, 8, 32, 128, and 1024 pulses at 10 Hz and for sequences of 1, 2, 8, 32, 128, and 1024 pulses at 16 Hz. Threshold damage is correlated by a power law of the form EDth = CN-alpha in which EDth is the threshold energy density and N is the number of pulses in the sequence. Temperature calculations reveal that the maximum temperature increase on the beam axis 10 micron beneath the anterior tear surface resulting from the different threshold exposures is essentially constant. This result is consistent with a critical peak temperature damage model and suggests that, at least for the multiple-pulse exposures, the damage mechanism may be predominately thermal. Damage threshold measurements on corneas maintained at 21 C indicated that the damage mechanism is indeed predominately thermal.

Descriptors :   *EYE, *INFRARED RADIATION, *CORNEA, DENSITY, TEMPERATURE, EPITHELIUM, COMPUTATIONS, DAMAGE, THRESHOLD EFFECTS, ENERGY, SURFACES, PULSES, TEARING.

Subject Categories : Anatomy and Physiology
      Radiobiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE