ABSTRACT
The angle of deviation was measured using the prism cover test at near (33cm) and distance (6m) before the start and at the end of a 5 day detoxification programme. In a subgroup of patients (n=38) measurements were also recorded on lateral gaze at distance. Eighty-three participants were seen pre detoxification (aged 27.1+4.6 years) and 69 post detoxification. A significant change in the distance angle of deviation in the eso direction was found (p<0.001), but the change in near angle was not significant. Right gaze measurements showed a median change of +2Δ (range -12Δ to +10Δ), not significant (p=0.098) and left gaze measurements showed a median change of+2Δ (range -8Δ to +10Δ), significant (p=0.01). A trend towards development of distance esotropia following detoxification from heroin and / or methadone appears to be present. However, the mechanism for this trend is probably not due to 6th nerve involvement as the increase in incomitance is considered too small to be clinically significant and it is suggested that the increase could be due to decompensation of pre-existing incomitance.
