Mr Greene attempted no explanation of this phenomenon, wisely leaving it until other experiments were forthcoming. He, however, strongly advised no repetition of the experiment with a 2,000 candle-power arc, for he had suffered from a black spot hovering about his retina for days afterward, this fact indicating that the retina is the source of the phenomenon. The matter dropped, mainly owing to the failure of others to obtain a a similar effect, the general opinion being that Mr Friese Greene possessed an eye of particular composition. After exposure, there is a period of latency varying somewhat inversely with the amount of exposure. The latent period may be as short as 30 min or as long as 24 hr, but is typically 6 to 12 hr.
Corneal pain can be severe.
The individual is usually incapacitated for some period of time. These acute symptoms usually last from 6 to 24 hr, and almost all discomfort disappears within 48 hr. Still, better safe than sorry. The next day Woodbury regained his sight, but at the time of writing 'my sight has rapidly deteriorated, not in the usual way, that is called old sight coming on, but in the form of a white glare or spot covering the centre of vision, so that, as I write this, the word I am writing only becomes visible when I get to the next one, spectacles being of little avail. Reading has also become entirely out of the question.