Effect of ageing and cataract formation on the Raman spectroscopic profile of human lens: An observational study

To observe the spectroscopic profile of human lens in different age groups and varying grades of cataract and to use the data to arrive at differentiating molecular biology.

An observational cross-sectional study.

The study enrolled 30 patients (30 eyes) with a mean age of 59.6 years diagnosed with immature senile cataracts. The patients underwent small incision cataract surgery, and the harvested lens nuclei were examined under a Raman spectroscope for studying their molecular composition. The relative intensities of the peaks in the Raman spectra were evaluated and compared among different age groups and grades of cataract. A correlation of tyrosine doublet ratio with grade of cataract and age of the subject was calculated.

Several Raman spectral peaks were observed in the range of 600 cm-1 to 1800 cm-1 with correspondence to tyrosine, phenylalanine, tryptophan, and amides I and III. A strong negative correlation between the grade of cataract and the ratio of tyrosine doublet was seen (r = -0.805). Also, a negative correlation between age and tyrosine ratio was seen (r = -0.62). The wavenumber/spectral peak of tryptophan was observed only in one sample, and amides I and III were identified, but the intensity of the peak for amide II was very small or absent.

It was observed that the buried conformation of tyrosine was predominant in cases with a higher age or grade of cataract. The buried conformation of tryptophan became less in the higher grades of cataract.