Retinal Prosthesis device has been approved by FDA for treatment of vision impairment caused by RP. Validating the visual distortion estimation algorithms used in prosthesis is crucial for the safe use of prosthesis. An approach based on metamorphic testing was described to validate a prosthesis distortion estimation algorithm. Four metamorphic relations including two necessary conditions for the correct functioning of the estimation algorithm were identified. Violations in two metamorphic relations were detected showing different estimation behavior of prosthetic vs. regular images and those having high distortions.