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

Abstract

Purpose: 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. Design: An observational cross-sectional study. Methods: 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. Result: 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. Conclusion: 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.