Compiled by BioPhotonics staff
LIVINGSTON, UK – A widely used method of monitoring protein
changes in biophysical research could become a clinically useful tool sensitive
enough to diagnose cataracts before significant damage, light scattering, aggregation
and visual impairment occur.
Cataracts are the leading cause of blindness worldwide, affecting
17 million people and resulting in 1.3 million operations annually in the US alone,
according to the World Health Organization.
Researchers at Edinburgh Instruments (EI), NHS Princess Alexandra
Eye Pavilion and Heriot-Watt University have explored the possibility of early cataract
detection by using tryptophan fluorescence, which can detect protein folding, conformation
and aggregation by virtue of shifts in the emission spectrum in different polar
Experiments with artificially created cataract lenses from pigs’
eyes – made by means of ultraviolet radiation – have shown that tryptophan
fluorescence offers a sensitive method for monitoring very early changes in the
lens structure that cannot be detected by the standard slit-lamp method. Spectral
measurements were taken using an EI FLS920 spectrometer in a temperature-controlled
1-cm quartz cuvette in phosphate buffer solution at 22 °C, retaining uniform
tissue viability over 16 hours.
Current methods for cataract detection are based on subjective
observation of lens opacity by Rayleigh light scattering. This method does not provide
the protein-level detail offered by tryptophan fluorescence, however, because of
limitations of the scattering techniques, so it cannot reveal structural changes
on a molecular level.
The new technique could help researchers establish the point at
which the irreversible crystalline protein change that triggers the need for surgical
intervention occurs. Clinical application of the method also will help in diagnosing
early stages of metabolic disorders, such as diabetes, and in deciding on preventive
The study was published in the March 31, 2011, issue of the Journal
of the Royal Society Interface (doi:10.1098/ rsif.2010.0608).