Thermal lensing in ocular media exposed to continuous-wave near-infrared radiation: the 1150–1350-nm region

Abstract

Ocular damage threshold data remain sparse in the continuous wave (CW), near-infrared (NIR) radiation region save for the 1300-nm area that has been investigated in the past several decades. The 1300-nm ocular damage data have yielded unusual characteristics where CW retinal damage was observed in rabbit models, but never in nonhuman primate models. This paper reviews the existing 1300-nm ocular damage threshold data in terms of the fundamental criteria of an action spectrum to assist in explaining laser-tissue effects from near-infrared radiation in the eye. Reviewing the action spectrum criteria and existing NIR retinal lesion data lend evidence toward the significant presence of thermal lensing in ocular media affecting damage, a relatively unexplored mechanism of laser-tissue interaction.

Influence of transverse mode on retinal spot size and retinal injury effect: A theoretical analysis on 532-nm laser

“…It is well known that the retinal spot size of infrared laser beam is much larger than that of visible laser, mainly due to dispersion e®ect. For example, the retinal spot diameter of 1060 nm laser for TEM 00 mode was about 90-120 m. [36][37][38] It can be inferred that compared with the visible light, the in°uence of the higher order transverse mode of infrared laser on the retinal spot size will be more remarkable. We will concentrate on this problem in subsequent research.…”

Thermal lensing in the ocular media

“…For a given wavelength, the initial values of (z) in the virtual eye are calculated from the ABCD propagation method described by Yariv from Eq. 4.6-10 using the corresponding bulk refractive index from the Sellmeier fit reported in Chapter 2 (see Table 2.5) (Vincelette, Rockwell et al 2008). The thermal conductivity, , specific heat at constant pressure, c p , and density, , of ocular media were held as constants reported in literature (Okuno, Kojima et al 2005).…”

“…Using these trends in refractive error, a bulk refractive index value as a function of wavelength was determined by a Sellmeier fit, as described in Chapter 2 and in an earlier publication by Vincelette, Rockwell et al, 2008, to account for chromatic dispersion in the eye model. For a given wavelength, the initial values of (z) in the virtual eye are calculated from the ABCD propagation method described by Yariv from Eq.…”

“…Similar fundamental understandings are necessary to estimate an action spectra used to make predictions on general trends by fitting available MVL data over the entire UVvisible-IR spectrum (Lund and Edsall 1999;Lund, Edsall et al 2000;Zuclich, Lund et al 2007;Vincelette, Rockwell et al 2008). To date, thermal lensing has been a relatively unexplored laser-tissue interaction in the eye and has not been incorporated in any eye model used to predict retinal damage thresholds.…”

“…(b) The percent of transmitted energy from the surface of the cornea to the retina for a rhesus eye (assuming no specular reflection) and the water-filled Cain cell (assuming 12% loss in energy from the Cain-cell lens) (Vincelette, Rockwell et al 2008). The average loss in the Cain cell lens was determined experimentally over a range of near-infrared wavelengths (see methods section).…”