Objective: Substance use has such effects on pupil diameter. Although there is knowledge about the acute effects of substances on pupils, studies showing their chronic effects are limited. The aim of the present study was to evaluate the effect of long-term substance use on scotopic, mesopic, and photopic vision. Methods: The present study with cross-sectional desgn was conducted at the Adiyaman Training and Research Hospital for Psychiatry in Adiyaman. This study involved 110 substance use disorder (SUD) patients and 46 healthy volunteers as the control. The parameters were measured and recorded automatically by a device. Results: The mean age was 23.44±5.53 years in the SUD group and 24.26±5.38 years in healthy controls (p=0.420). The mean age of onset of the substance was 17.74±3.89 years and the mean duration of substance use was 3.54±2.9 years. It was determined that the patients had not used any substance for a mean of 121.73±117.49 days. There was no significant difference between patient and control groups in terms of scotopic and mesopic measurements of both eyes (p>0.05). Photopic measurements were significantly higher in the patient group than in the control group (p<0.05). Photopic measurements were significantly higher in the opioid, cannabis, ecstasy, and multiple substance use groups than in the control group (p<0.05). Conclusion The most important topic of this study is that photopic vision is permanently impaired in patients with a history of chronic substance use. This was attributed to disrupted sympathetic-parasympathetic hierarchy.