Characterization of cataractous lenses of Sprague – Dawley rats using selected optical spectroscopic techniques

Abstract

Current methods for discriminating cataractous lenses from healthy lenses during preclinical studies are based on either histopathological or clinical assessments which are weakened by subjectivity. In this work, four optical spectroscopic techniques: slit lamp microscopy, multispectral imaging (MSI), Laser-induced autofluorescence (LIAF) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy have been used to study and characterize cataractous as well as healthy lenses of Sprague Dawley rats. With the aid of slit lamp images, mean integrated optical density (IOD) of cataractous lenses were found to increase with severity. Analysis of multispectral images captured in transmission and reflection and scattering modes showed that five wavelengths markers discriminates cataractous lenses from healthy lenses with 470 nm and 625 nm in reflection mode, and 435 nm, 590 nm and 700 nm in transmission mode. The scattering spectral bands could not discriminate cataractous lenses from healthy lenses. Fisher‟s linear discriminant analysis showed more than 85 % success in classifying the lenses. LIAF results revealed that spectra peak wavelengths of cataractous lenses were red-shifted with cataractous lens tissues exhibiting high autofluorescence intensity than the healthy ones. Infrared spectra from cataractous lens tissues showed intensity difference and some wavenumber shifts in vibrational modes associated with proteins from the healthy ones. P-values obtained from independence T-test showed significant differences in absorbed intensities at 7 peak wavenumbers. Upon applying Hierarchical cluster analysis, the infrared lens spectra data were classified as cataractous or healthy. These optical techniques may be potentially applied for improved cataract diagnosis.