A Generation II night vision pocketscope has been shown to be effective in eliminating the symptom of night blindness in patients with retinitis pigmentosa. This pocketscope provides sufficient light amplification to allow cone function under scotopic conditions. Minimum pocketscope gain and minimum output screen luminance required for mobility by these patients under scotopic conditions are correlated with their cone threshold elevations above normal. Instrument gain and output screen luminance should be minimized to extend the period of usefulness of the instrument and to protect the patient against the possible harmful effects of excessive light exposure. The advantages of a wide-angle lens and infrared light-emitting diode, attached to the pocketscope, are considered.
Berson EL, Mehaffey L, Rabin AR. A Night Vision Pocketscope for Patients With Retinitis PigmentosaDesign Considerations. Arch Ophthalmol. 1974;91(6):495-500. doi:10.1001/archopht.1974.03900060509018