You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Disease", "Chemical"].

Please return the output as a JSON object of the format: {"Chemical" : ["Naloxone", ...], "Disease" : ["Hypotensive", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Effect of myopic excimer laser photorefractive keratectomy on the electrophysiologic function of the retina and optic nerve. PURPOSE: To assess by electrophysiologic testing the effect of photorefractive keratectomy (PRK) on the retina and optic nerve. SETTING: Eye Clinic, S. Salvatore Hospital, L'Aquila University, Italy. METHODS: Standard pattern electroretinograms (P-ERGs) and standard pattern visual evoked potentials (P-VEPs) were done in 25 eyes of 25 patients who had myopic PRK for an attempted correction between 5.00 and 15.00 diopters (D) (mean 8.00 D). Testing was done preoperatively and 3, 6, 12, and 18 months postoperatively. The contralateral eyes served as controls. During the follow-up, 3 patients (12%) developed steroid-induced elevated intraocular pressure (IOP) that resolved after corticosteroid therapy was discontinued. RESULTS: No statistically significant differences were seen between treated and control eyes nor between treated eyes preoperatively and postoperatively. CONCLUSION: Myopic excimer laser PRK did not seem to affect the posterior segment. The transient steroid-induced IOP rise did not seem to cause functional impairment.
{"Chemical": ["steroid", "corticosteroid"], "Disease": ["IOP rise", "elevated intraocular pressure"]}