Principles of the present disclosure are directed to novel methods and devices for focal or global optical stimulation of retina and detecting activity of the retina by collecting and processing the back-scattered optical signal from the retina (Optical RetinoGram). Specifically, the invention provides device and method for quantitatively determining the layer specific activity of retina from the acquired intrinsic back reflected signal by monitoring phase/intensity fluctuations and thereafter employing multifractality algorithm on optical signal for obtaining various multifractal parameters such as width of singularity spectrum, Hurst exponent, fractal dimension, locally connected fractal mapping as well as artificial intelligence based classification for the use of diagnosis of retinal degenerative/ocular disease(s) and asses the progression of diseases or recovery of function due to one or more treatment by therapeutic drugs, devices, protocols.