An instrument for determining macular pigment of a macula of an eye of a user, characterized in: a housing including a lower hand-held portion (12, 112) with a user-input button (24, 124) configured for actuation by the user and a display (26, 126) for displaying an MPOD score for the user, the lower hand-held portion (12, 112) further including a battery (28, 128) and electronics for operating the instrument (10, 110); and a viewing tube (14, 114) coupled to the hand-held portion (12, 112) and terminating in an eye cup (16, 116) configured to be placed over the eye of the user, the viewing tube (14, 114) being transverse to the lower hand-held portion (12, 112), the viewing tube (14, 114) including a light source (30, 130) for transmitting light and a blocking wall (33, 133) with an aperture (34, 134) adjacent to the light source (30, 130), the viewing tube (14, 114) further including a light ring (32, 132) with a center opening, the light ring (32, 132) being located between the blocking wall (33, 133) and the eye cup (16, 116), the light source (30, 130) is located in the viewing tube (14, 114) such that the light is transmitted through the aperture (34, 134) of the blocking wall (33, 133), through the center opening of the light ring (32, 132), and toward the eye cup (16, 116), the light source (30, 130) providing two colored lights alternating at an initial frequency that is not perceptible by the user, the frequency decreasing from the initial frequency until the user activates the user-input button (24, 124) in response to a frequency at which the user perceives a flicker of the two colored lights, the perceived frequency being used to for determining the MPOD score for the user. a housing including a lower hand-held portion (12, 112) with a user-input button (24, 124) configured for actuation by the user and a display (26, 126) for displaying an MPOD score for the user, the lower hand-held portion (12, 112) further including a battery (28, 128) and electronics for operating the instrument (10, 110); and a viewing tube (14, 114) coupled to the hand-held portion (12, 112) and terminating in an eye cup (16, 116) configured to be placed over the eye of the user, the viewing tube (14, 114) being transverse to the lower hand-held portion (12, 112), the viewing tube (14, 114) including a light source (30, 130) for transmitting light and a blocking wall (33, 133) with an aperture (34, 134) adjacent to the light source (30, 130), the viewing tube (14, 114) further including a light ring (32, 132) with a center opening, the light ring (32, 132) being located between the blocking wall (33, 133) and the eye cup (16, 116), the light source (30, 130) is located in the viewing tube (14, 114) such that the light is transmitted through the aperture (34, 134) of the blocking wall (33, 133), through the center opening of the light ring (32, 132), and toward the eye cup (16, 116), the light source (30, 130) providing two colored lights alternating at an initial frequency that is not perceptible by the user, the frequency decreasing from the initial frequency until the user activates the user-input button (24, 124) in response to a frequency at which the user perceives a flicker of the two colored lights, the perceived frequency being used to for determining the MPOD score for the user.