Mydriatics decrease small intestinal motor activity and gastric empyting after routine eye exams in preterm infants

In a retrospective review, we found that about 30% of premature infants experience clinically significant feeding intolerance after screening eye exams for retinopathy of prematurity. We hypothesized that the mydriatics used for these exams are absorbed systemically and affect gastrointestinal function. We performed continuous small intestinal manometry and assessed gastric emptying by the method of George. Eight preterm infants were studied continuously for 10 hours, with a fasting-feeding cycle, instillation of a standard dose of mydriatics (Cyclomydril), eye examination, and a second fasting-feeding cycle. Measurement Units Before Mydriatrics After Mydriatics Heart Rate (Beats/min) 162 ± 2 163 ± 4 Mean Arterial BP (mmHg) 52 ± 4 46 ± 1 Duodenal Peaks (#/30 min) 101±17 23 ± 8* Duodenal Quiescence (min/hr) 15±2 25±1* % Emptied @ 40 mm % 61±10 50± 8+ % Remaining @ 2hr % 5 ± 3 8 ± 1 *p < 0.001 and + p < 0.03; both paired t test (mean ± SEM). Mydriatics profoundly impaired intestinal functions, but did not affect cardiovascular measurements. The overall decrease in duodenal motor activity after the instillation of mydriatics was reflected in a significant decrease in gastric emptying. Instillation of mydriatics has a profound effect on gastorintestinal function and feeding regimens may need to be modified on the day of the routine eye exams in preterm infants.