Fig. 1
From: Long term positional stability of the Argus II retinal prosthesis epiretinal implant
Fundoscopy of patient A-03 at month 24 post implantation with markings to show distances and angles that were recorded using NIH ImageJ: A A represents the point in the center of the optic disc, B is the point at the top corner of the surgical handle on the implant, C is the point in the center of the tack. Alpha (α) represents the ∠CAB, gamma (Ɣ) represents the ∠ACB, beta (β) represents ∠ABC. B delta (𝜟) measures the angle made by the line along the edge of the implant to the horizontal of the image frame