AIM:To investigate the impact of cirrhosis on retinal morphology and to evaluate the role of endogenous opioids as a mediator in cirrhosis induced retinal change.METHODS:Thirty-six male rats were divided into 3 main groups; the common bile duct ligated (BDL) group, the sham-operated (Sham) group and the unoperated (Unop) group. Then each of these three main groups was divided into two subgroups; the first subgroup received daily injection of naltrexone hydrochloride (NTX) and the second group was injected with normal saline (Saline) daily. After 28d, rats were anesthetized and their right eyes were enucleated and assessed for histological changes. The thickness of the rod and cons layer, outer nuclear layer, outer plexiform layer, inner nuclear layer, inner plexiform layer and ganglion cell layer for each eye were measured in micrometers by light microscope.RESULTS:Ganglion cell layer showed significant increase in thickness in the BDL group (P<0.05). This increase was eliminated in the group where BDL rats received daily intraperitoneal injection of naltrexone hydrochloride (20 mg/kg). No other histological changes were detected in the other 5 layers we measuredCONCLUSION:The morphological change we detected in the retina of cirrhotic rats is probably due to opioids increased tone in cirrhosis since the increase in thickness in the ganglion cell layer was almost eliminated when naltrexone hydrochloride was injected. These results suggest a possible role for endogenous opioids in the morphological retinal changes detected in cirrhotic rats.