August C Schumacher,1 Michelle L Ball,2 Andrew W Arnold,3 Robin L Grendahl,4 R Kevin Winkle,4 Robert W Arnold5 1US Ski Team, Alaska Winter Stars, Anchorage, AK, USA; 2Pediatric Department, Alaska Native Medical Center, Anchorage, AK, USA; 3College of Osteopathic Medicine, Pacific Northwest Universit, Yakima, WA, USA; 4Alaska Children’s EYE & Strabismus, Anchorage, AK, USA; 5Alaska Blind Child Discovery, Alaska Children’s EYE & Strabismus, Anchorage, AK, USACorrespondence: Robert W ArnoldAlaska Blind Child Discovery, Alaska Children’s EYE & Strabismus, 3500 Latouche #280, Anchorage, AK 99508, 99508 Tel +1 907 561-1917Fax +1 907 563-5373Email eyedoc@alaska.netPurpose: Reducing physiologic stress including bradycardia during staging eye exams for retinopathy of prematurity (ROP) is desirable. We observed heart rate change during routine retinopathy of prematurity eye examinations and compared the response with our ongoing study of oculocardiac reflex (OCR) elicited by uniform EOM tension during strabismus surgery.Patients and Methods: Electrocardiograph was prospectively monitored during ROP exams featuring indirect ophthalmoscopy with Alfonso lid speculum and see-through scleral depressor without topical anesthesia. Clinical data were retrieved from ROP-Check software. OCR was defined as maximally changed heart rate (HR) as a percent of baseline. Strabismus surgery patients under general anesthesia served as controls.Results: From 10/2017 to 9/2020, 281 infants had ROP exams, and the median OCR was 55.9% of baseline HR (IQR 41.4% to 72.6%), the kurtosis 0.93 and skewness 1.01 representing a drop from HR 169 ± 16 bpm to 102 ± 39 bpm. In comparison, 1493 adult and pediatric strabismus surgery patients had less OCR median bradycardia 87.8% (IQR 72– 98%), kurtosis 1.60 and skewness − 1.18. ROP %OCR correlated with birth gestational age (%OCR = 2.5 (GA) – 11, r(279)=0.33, p< 0.01) and with birthweight (%OCR = 0.02 (BW) + 38, r(279) =0.35, p< 0.01). The duration of bradycardia induced by ROP exam averaged 92 ± 34 seconds (range 34– 240 seconds).Conclusion: Bradycardia is common during eye exams in the smallest premature infants with greater degree, more rapid onset and longer duration than OCR during strabismus surgery.Keywords: bradycardia, retinopathy of prematurity, strabismus