Mechanism
Most vision researchers believe that phosphenes result from the normal activity of the visual system after stimulation of one of its parts from some stimulus other than light. For example, Grüsser et al. showed that pressure on the eye results in activation of retinal ganglion cells in a similar way to activation by light. An ancient, discredited theory is that light is generated in the eye. A version of this theory has been revived, except, according to its author, that "phosphene lights are [supposed to be] due to the intrinsic perception of induced or spontaneous increased biophoton emission of cells in various parts of the visual system (from retina to cortex)"

Anthropological research
In 1988, David Lewis-Williams and T. A. Dowson published an article about phosphenes and other entoptic phenomena. They argued that non-figurative art of the Upper Paleolithic depicts visions of phosphenes and neurological "form constants", probably enhanced by hallucinogenic drugs. Research
Research has looked into visual prosthesis for the blind, which involves use of arrays of electrodes implanted in the skull over the occipital lobe to produce phosphenes. There have been long term implants of this type. Risks such as infections and seizures, have been an impediment to their development. A possible use of phosphenes as part of a brain to brain communication system has been reported. The system called BrainNet, produces phosphenes using transcranial magnetic stimulation (TMS).
The goal of the research is to connect thoughts brain to brain using a system where signals are detected using electroencephalography (EEG) and  delivered using transcranial magnetic stimulation (TMS). An experiment was conducted with 5 different groups, each contained three people. The subjects were split into two groups. Two subjects functioned as the senders, and were connected to EEG electrodes, and a third person functioned as the receiver, who wore the TMS helmet. Each person was stationed in front of a television screen with a Tetris-style game. The senders had to determine if there was a need to rotate the falling blocks, but without the ability to rotate them – only the receiver was able to perform this operation. At the edges of each screen, were two icons with two flashing lights in two different frequencies, (one at 15 Hz and the other at 17 Hz). The sender focused on one icon, or the other to signal that the block should be rotated to the right or the left. The EEG produced a unique signal, which was transmitted to the TMS helmet of the receiver, who perceived phosphenes which differed for the 15 Hz and 17 Hz  signal, and rotated the block in the relevant direction. The experiment achieved 81% success. See also
References
External links
https://www.oubliette.org.uk/ Entoptic Phenomena: Review of J. D. Lewis-Williams and T. A. Dowsons researchhttps://www.wynja.com/arch/entoptic.com Altered States: Review of J. D. Lewis-Williams and T. A. Dowsons researchBiophysical pictures within the brain