PBM was done by asking the patients to see sunlight for cumulative 5 minutes using a yellow narrow band filter which allowed light of wavelength 570 nm to pass through it.
The time duration of exposure was calculated as follows:
The light intensity at a particular area was measured in Lux.
Standard sunlight intensity = 15,000 Lux.
Already established luminous efficacy of sun = Lumens per Watt – 93lm/w
Surface area of macula = 1094 mm2
Net power delivered is 0.1764 W.
Total energy = W * T = 0.1764 * 180
= 31.752 J/cm