Probing temporal structural changes within cornea using 200 kHz swept source nano sensitive optical coherence tomography (nsOCT)

Non-invasive imaging modalities, especially optical coherence tomography (OCT) are capable of providing high resolution structural and functional imaging capabilities for ophthalmic applications. Apart from functional imaging, OCT has also been used to extract functional dynamics within the microvasculature in response to changes in local environment. In mammals, various physiological processes, such as energy metabolisms, cardiovascular functions and circadian rhythms exhibit fluctuations in response to change in the local and external environment. These rhythmic oscillations within the body have been observed within the neurons, microvasculature, muscles and heart and play a vital role in modulating the biological processes and associated physiological response by an organism. Cornea is the transparent, avascular layer of the eye that controls the entry of light into the eye and also helps to refract the light onto the retina. Corneal injuries caused by various chemical, physical, and pathological stimuli damages the corneal epithelium, the stroma and the endothelium, thereby hindering its proper functioning. The maintenance of corneal transparency is vital for optimum vision, and this is ensured by the avascular cornea evenly spaced collagen fibrils of uniform diameter within the stroma, and also the level of hydration within the stromal layer. Recently, nano-sensitive OCT (nsOCT) technique has been proposed by our group that retains the high spatial frequency information in an OCT image, thereby enabling the detection of nanoscale structural alterations in in vivo imaging of tissues. In this paper, we describe nsOCT based approach to detect the dynamic/temporal structural changes within the cornea following an alkali injury using a high speed swept source OCT.