Spectroscopic investigation of retinal degeneration unravel molecular changes associated with vision impairment.

Although retinal degeneration is one of the causes of blindness worldwide and involve the loss of the photoreceptors of the retina, the cause(s) of its development still need to be determined in order to reach an effective treatment instead of trying to slow the progression of the disease. Retinal degeneration condition was induced by intravitreal injection of 2 µl of adenosine triphosphate (ATP) solution. The progress of the disease was monitored by retinal imaging (ocular coherence tomography, OCT) after 1, 8 and 15 days of injecting ATP. At the end of each period, retinal tissue was obtained where retinal proteins were extracted and then subjected to spectroscopic studies. Another part of the retinal tissue was investigated by Fourier transform infrared spectroscopy. The OCT images reflect significant reduction in retinal full thickness and provide evidence of intraretinal inflammation while; the obtained results indicate that both primarily and secondary structure of retinal proteins are influenced by the degeneration condition and, the electrical conductance of retinal proteins is decreased due to degeneration condition. Multivariate principal component analysis identifies that the variance noticed in the infrared spectra due to degeneration condition is not time dependent and revealed intra-groups structural dissimilarity. This dissimilarity was clearly resolved by fluorescence study where the content of amino acids phenylalanine, tryptophan and tyrosine varies with the progress of the degeneration condition. All together provide scientific facts that vision impairment is due to loss of signal transduction and formation of protein aggregates as well.