摘要： PURPOSE. To study the effects of acute optic nerve damage on the re?ectance of the retinal nerve ?ber layer (RNFL) and to compare the time courses of changes of RNFL re?ectance and thickness. METHODS. A rat model of optic nerve crush (ONC) was compared with previously studied normal retinas. The re?ectance and thickness of the RNFL were studied at 1 to 5 weeks after ONC. Re?ectance spectra from 400 to 830 nm were measured for eyes with ONC, their contralateral untreated eyes, and eyes with sham surgery. Directional re?ectance was studied by varying the angle of incidence. RNFL thickness was measured by confocal microscopy. RESULTS. After ONC, the RNFL re?ectance remained directional. At 1 week, RNFL re?ectance decreased signi?cantly at all wavelengths (P < 0.001), whereas there was no signi?cant change in RNFL thickness (P ? 0.739). At 2 weeks, both RNFL re?ectance and thickness decreased signi?cantly, and by 5 weeks they declined to approximately 40% and 30%, respectively, of the normal values. Although RNFL re?ectance decreased at all wavelengths, there was a greater reduction at short wavelengths. Spectral shape at long wavelengths was similar to the normal. Some of these changes were also found in the contralateral untreated eyes, but none of these changes were found in eyes with sham surgery. CONCLUSIONS. Decrease of RNFL re?ectance after ONC occurs prior to thinning of the RNFL and the decrease is more prominent at short wavelengths. Direct measurement of RNFL re?ectance, especially at short wavelengths, may provide early detection of axonal damage.