Optical properties of conjunctiva, sclera, and the ciliary body and their consequences for transscleral cyclophotocoagulation

Abstract

A number of recent studies have demonstrated the success of Nd:YAG and diode laser transscleral cyclophotocoagulation in the treatment of advanced glaucoma. Wavelength selection, however, has seldom been based on a clear understanding of the optical properties of tissues involved. The optical properties of conjunctiva, sclera, and the ciliary body adjacent to the limbus were investigated to find an optimal wavelength range for transscleral cyclophotocoagulation. The absorption and scattering coefficients of these layers were determined in the 300-1200-nm wavelength range by the use of a one-dimensional inverse adding-doubling method. The measured optical properties of conjunctiva, sclera, and the ciliary body provide a basis for a comparative analysis of the laser wavelengths used clinically for transscleral cyclophotocoagulation.

Optical properties of human stomach mucosa in the spectral range from 400 to 2000 nm

“…Doornbos et al 31 , and the factor b has been estimated from the fitting as 12 1.027 10 × . In Figure 4 is seen, that the combination of the wavelength dependencies of the Rayleigh and Mie scattering very well describes the measured wavelength dependence of the reduced scattering coefficient.…”

“…The IAD method is widely used in tissue optics for processing the experimental data of spectrophotometry with integrating spheres [10][11][12][13][14][15][16] . This method allows one to determine the absorption ( ) These losses depend on the physical size and geometry of the sample, i.e., the losses existing in the case, when the sizes of a sample do not exceed significantly the diameter of the incident beam.…”

Flexible Optical Waveguides for Uniform Periscleral Cross-Linking

“…SXL-induced changes in elastic moduli can depend greatly on sample preparation and analysis procedure, but our results are generally consistent with previous studies using riboflavin and porcine eyes. 17,28,29 Light penetration into scleral tissue is limited by its high optical scattering properties; at 445 nm, the scattering coefficient 30 is ∼80 cm− 1 . Factoring in riboflavin absorption (∼135 cm −1 at 0.5% concentration), we anticipate cross-linking of less than 100 μm of scleral tissue in depth, much less than the full thickness (>350 μm).…”

Etalon filters for Brillouin microscopy of highly scattering tissues

“…The laser power was 5 mW on the sample surface. The light scattering coefficients of the conjunctiva are known to be similar to those of chicken breast tissues, and the light scattering from the sclera is about 10 times stronger than the scattering from the conjunctiva [17]. Different camera integration times of 1, 2, and 4 s were used for the cornea, conjunctiva, and sclera, respectively, to compensate for the reduced signal strength proportional to the amount of light scattering.…”