This study aims to evaluate how effectively sunglass frames protect the wearer’s eyes from ambient diffuse light. While current sunglasses standards focus mainly on ensuring safe levels of lens transmittance between 280 nm and 380 nm, [1] not 400 nm, it’s important to consider the role of sunglass frames in shielding the eyes from ultraviolet exposure of the direct and backscattered solar light [6]. To achieve this goal, a prototype was developed to simulate diffuse light conditions and measure how well frames block light from reaching the eyes when wearing sunglasses. The prototype includes an UV LED-illuminated sphere, a mannequin head with photodiode sensors, and a detailed set of baseline and measurement procedures. Initial tests at the Laboratory of Ophthalmic Instrumentation (LIO) have shown variations in light-blocking effectiveness among different frame types and geometry.