Abstract
Purpose: :
To examine the effects of nicotine gum [2mg and 4mg] on color vision in healthy adults who are not smokers.
Methods: :
Two healthy, non-smokers (24-25 years old) received a comprehensive eye exam including VF and color assessment to determine eligibility. Subjects were tested in three separate sessions: 1) without nicotine; 2) 2mg nicotine gum; 3) 4mg nicotine gum. The Farnsworth-Munsell Hue test (FM-100) and the Red Test (RT; York & Loop, 2008) were used to examine color discrimination and threshold increment detection, respectively. FM-100 was administered 30 minutes after chewing the gum. Total Error Score (TES) from the FM-100 was calculated after each test. The RT was administered at intervals of 10, 20, and 30 minutes while chewing the gum. Thresholds from the RT were determined at each interval for both red (620nm dominant ) and white (7100K) lights.
Results: :
The FM-100 test showed substantial decreases in TES across the two nicotine gum conditions, with more changes seen with the 4mg dose. Results from the RT showed decreases (improvement) in threshold detection across time during the intake of 2mg and 4mg nicotine gum, with more pronounced changes in a) the 2mg than the 4mg, and b) white light than red light.
Conclusions: :
Using the D-15 panel test, Bimler and Kirkland (2004) reported significantly worse sensitivities to red-green color in smokers compared to non-smokers. In addition, Erb et al. (1999) showed that heavy smokers (>20 cigs/day) had higher error scores on the Roth-28 color test compared to both controls and light smokers (≤20 cigs/day). Previous studies showed that nicotinic receptors exist throughout the human body including the retina, LGN, and visual cortex. Studies from our lab have observed changes in ERG responses with nicotine1. This project extends our previous findings to explore psychophysically observable changes in the visual system. Our preliminary data implicate nicotine as the possible substance responsible for changes in color vision seen with our subjects. It is also possible that changes seen in previous studies with "smokers" and "cigarettes" are not strictly attributable to nicotine alone (e.g. smoking behavior, other substances in tobacco), or only occur after extended exposure to nicotine. Testing of additional subjects is planned to further evaluate our hypothesis.1- Varghese et al., IOVS 2009;50:ARVO E-Abstract 2183
Keywords: color vision • perception • color appearance/constancy