Abstract
Introduction: Opioids are addictive substances that have been shown to have neurotoxic effects on the brain. These neurotoxic effects may be associated with retinal nerve fiber layer (RNFL) thickness. This study aims to examine retinal neural fiber layer thickness by optical coherence tomography (OCT) among opioid addicts.
Method: Therefore, both eyes of the 45 participants who met the diagnosis of opioid addiction according to DSM-5 (age: 26.13±6.20 years) and 45 healthy controls (age: 28.87±9.04 years) were examined in seven quadrants (superior temporal, superior nasal, temporal, nasal, inferior temporal, inferior nasal quadrants and global RNFL thickness) with OCT.
Results: Mean RNFL thicknesses in any quadrant did not differ statistically significantly between the groups (p>0.05). Furthermore, there was no statistically significant correlation between the duration of substance use and RNFL thicknesses. There is a statistically significant inverse correlation that has been found between the daily amount of substance use (gr)and RNFL thicknesses in the right eye temporal inferior (r: -0,499) and temporal superior (r: -0,351) and left eye nasal inferior (r: -0,387) quadrants, whereas there was not any statistically significant correlation in other quadrants.
Discussion: This study suggests that RNFL thickness may be the same as healthy controls for several reasons in opioid addicts. It would be appropriate for this to be confirmed by broader studies and for its mechanism to be investigated.

Key words: Optic coherence tomography, opioid, heroin, retinal nerve fiber layer