A comparison of the pupillary and cardiovascular effects of various mydriatic agents in preterm infants

The effects of mydriatic eye drops on cerebral blood flow and oxygenation in retinopathy of prematurity examinations

Mydriatic eye drops used during retinopathy examination have been associated with cardiovascular, respiratory, and gastrointestinal side effects. The aim of our study was to investigate the effects of the drops used for pupil dilatation on cerebral blood flow and cerebral oxygenation. The study included 62 infants who underwent retinopathy screening exams. Vital signs, heart rate (HR), arterial oxygen saturation (SpO2), and mean arterial pressure (MAP) were recorded. Cerebral oxygenation and middle cerebral artery blood flow velocity were evaluated using near-infrared spectroscopy (NIRS) and Doppler ultrasonography, respectively, and the cerebral metabolic rate of oxygen (CMRO2) was also calculated. The mean gestational age of the infants included was 31.29 ± 1.42 weeks, and the mean birth weight was 1620 ± 265 g. Heart rate was found to be significantly decreased after mydriatic eye drop instillation; however, there were no significant differences regarding blood pressure and oxygen saturation levels (HR: p < 0.001; MAP: p = 0.851; SpO2: p = 0.986, respectively). After instillation while cerebral regional oxygen saturation (rScO2) measurements were significantly decreased at the 60th minute (p = 0.01), no significant difference was found in Vmax and Vmean of MCA before and after mydriatic eye drop instillation (p = 0.755, p = 0.515, respectively). Regarding CMRO2 measurements, we also did not find any statistical difference (p = 0.442).    Conclusion: Our study has shown that although eye drops may affect heart rate and regional cerebral oxygen saturation, they do not alter cerebral blood flow velocities and metabolic rate of oxygen consumption. Current recommendations for mydriatic eye drop use in retinopathy exam appear to be safe. What is Known: • Mydriatic eye drop installation is recommended for pupil dilatation during ROP screening exams. • It's known that mydriatics used in ROP examination have affects on the vital signs, cerebral oxygenation and blood flow. What is New: • This is the first study evaluating the changes in cerebral oxygenation and blood flow velocity after mydriatic drop instillation using NIRS and Doppler US concomitantly. • While the eye drops may affect heart rate and regional cerebral oxygen saturation, they do not alter cerebral blood flow velocities and metabolic rate of oxygen consumption.

Systematic review of mydriatics used for screening of retinopathy in premature infants

INTRODUCTION

Routine retinopathy of prematurity eye examinations are an important part of neonatal care, and mydriatic medicines are essential in dilating the pupil for the eye examination. There are concerns about the level of evidence for efficacy and safety of these mydriatic medicines.

OBJECTIVE

This review evaluates both efficacy and safety evidence of mydriatics used during the retinopathy of prematurity eye examination.

METHOD

Systematic literature review.

RESULTS

There is limited evidence guiding clinical practice for safety and efficacy of mydriatics. The majority of publications are underpowered and with an unclear to high level of bias. There are a wide variety of mydriatic regimens evaluated for efficacy and safety, and multiple regimens are associated with case reports.

CONCLUSIONS

Current international guideline seems unnecessarily high, especially when the reviewed literature suggest that lower doses are effective, albiet from underpowered studies. The lowest effective combination regimen appears to be phenylephrine 1% and cyclopentolate 0.2% (1 drop). Microdrop administration of this regimen would further increase the safety profile, however, efficacy needs to be assessed.

[Serious adverse side effects after pupillary dilation in preterm infants]

PURPOSE

This study aimed at investigating serious side effects of the pupillary dilation protocol used in Caen University Hospital for the screening of retinopathy of prematurity. This protocol includes one drop of phenylephrine 5% and two drops of tropicamide 0.5% instilled at a 5-minute interval.

PATIENTS AND METHODS

This retrospective study included all premature infants with a birth weight less than or equal to 1500 g and/or a gestational age less than or equal to 30 gestational weeks, hospitalized in the neonatal intensive care unit of Caen University Medical Center, having ocular fundus examinations for retinopathy of prematurity screening between 2009 and 2014. The medical records of patients who died or developed necrotizing enterocolitis were reviewed to analyze the imputability of the two eye drops used for pupil dilation.

RESULTS

Five-hundred and twelve infants were included, corresponding to 1033 ocular fundus examinations. No case of death could be ascribed to the use of eye drops. Two cases of necrotizing enterocolitis could be ascribed to the use of tropicamide with a doubtful and plausible intrinsic imputability according to French imputability criteria.

CONCLUSION

The pupillary dilation protocol used in Caen University Hospital for screening of retinopathy of prematurity might be implicated in two cases of necrotizing enterocolitis with an uncertain imputability of tropicamide 0.5% eye drops. No serious side effect could be ascribed to the use of phenylephrine 5% eye drops in this study.

Transient ileus associated with the use of mydriatics after screening for retinopathy of prematurity in a very low birth weight infant

Very low birth weight (VLBW) infants have ophthalmologic examinations for retinopathy of prematurity (ROP) prior to discharge, with appropriate follow-up and intervention where appropriate. Eye drops such as cylopentolate, tropicamide, and phenylephrine are used at different concentrations to provide proper pupil dilation for screening ROP. Topical instillation of eye drops may cause mild or severe ocular or systemic adverse effects. Early recognition of systemic toxicity after eye drop instillation is important. The authors present a case of a VLBW infant who developed significant abdominal symptoms (mimicking ileus) that were significant enough to discontinue oral feeding after ocular instillation of 0.5% tropicamide and 2.5% phenylephrine eye drops for routine examination of ROP. After structural and functional gastrointestinal disorders and sepsis were excluded, symptoms resolved completely after discontinuation of the drug. This report is thought to be the first in the medical literature to address 5% tropicamide and 2.5% phenylephrine eye drops, and the combination that may lead to serious complication after ROP examinations.

A randomized controlled trial to determine the lowest effective dose for adequate mydriasis in premature infants

PURPOSE

To compare the mydriatic efficacy of different numbers of eye drops for retinal examination of premature infants.

METHODS

This pilot study enrolled preterm infants born at <32 weeks' gestational age who were scheduled for retinopathy of prematurity screening examinations. In all study group assignments, the right (treatment reference group) eye received 3 eye drops per current neonatal intensive care unit protocol, whereas the left (test) eye was randomized at each examination to receive either: 0, 1, or 2 drops. Pupils were dilated with the use of a cyclopentolate 0.2% and phenylephrine 1% ophthalmic solution. Pupil size (in mm) was measured by a single examiner at 0 (baseline), 45, 90, and 120 minutes after instillation. Retinal examination occurred at the first opportunity to adequately visualize the peripheral retina. Comparison of the means was calculated using paired t test, t test, or analysis of variance, as appropriate.

RESULTS

A total of 64 eye examinations were performed on 15 enrolled infants (mean gestational age, 28.7 ± 2.6 weeks, 53% white; 40% male). No significant differences existed in mean pupil size between the 1-, 2- and 3-drop groups at baseline, 90 minutes, and 120 minutes. All 1-drop group eyes could be examined by 90 minutes. The 0-drop group maintained baseline size.

CONCLUSIONS

Effective mydriasis was achieved in the test eye with 1 or 2 drops and was sustained to 120 minutes. Therefore, retinal examinations could be completed by 90 minutes in most infants with the use of 1 drop. A larger study is needed to determine the effect of iris color and severity of ROP on these findings.

Zentralnervöse Atemdepression als Komplikation der Behandlung des kongenitalen Glaukoms mit Brominidin-Augentropfen

We report the case of a premature newborn (gestational age 33 weeks) with congenital glaucoma. After a trabeculotomy high intraocular pressure persisted, leading to adjuvant treatment with timolol and--when the infant was 3 weeks old--with brimonidine. After the first application of topical brimonidine the infant developed such severe apnoeic spells that intubation and temporary ventilation were necessary. A review of the literature reveals that when used in young infants brimonidine eye drops can potentially have toxic effects on the central nervous system (e.g. respiratory depression). The use of topical brimonidine is therefore not advised in this age group.

Effects of three mydriatic drug regimens on pupil size in rhesus (Macaca mulatta) and African green monkeys (Chlorocebus aethiops)

BACKGROUND

Human mydriatric drug use in non-human primates (NHPs) has been documented but not quantified and compared for effectiveness. The objective of this study was to determine which drug regimen provided the most effective and consistent mydriatic effect for ophthalmologic examinations and other procedures. Secondary objectives were to determine average time to maximum dilation and whether species differences existed.

METHODS

Twelve rhesus and 12 African green monkeys were randomly assigned to one of six treatment combinations to test the mydriatic effects of three drug regimens: (1) tropicamide 1% (T); (2) tropicamide 1% and phenylephrine hydrochloride 2.5% (TP); and (3) tropicamide 1%, phenylephrine HCL 2.5% and cyclopentolate 1% (TPC). Left and right eyes of each monkey received a different drug regimen, depending on random assignment.

RESULTS

TPC showed a significantly larger mydriatic response in both species than T alone. Average time to maximum dilation with all three drug regimens was 50-60 minutes. Rhesus had a larger response to the mydriatic drug regimens than the African green monkeys.

CONCLUSIONS

The TPC regimen had the largest and longest lasting mydriatic effect in both species.

Comparison of mydriatic regimens used in screening for retinopathy of prematurity in preterm infants with dark irides

PURPOSE

To determine the mydriatic regimen that provides optimal dilation of the pupil with minimal systemic side effects for screening of retinopathy of prematurity.

METHODS

This cross-sectional, randomized, double-masked clinical trial compared cyclopentolate 1% + phenylephrine 2.5%, tropicamide 1% + phenylephrine 2.5%, and a prepared combination of cyclopentolate 0.2% with phenylephrine 1% for pupillary dilation in preterm infants with dark irides. Thirteen infants were randomized to each regimen. Outcomes measured were pupillary dilation, heart rate, blood pressure, abdominal girth, and intolerance to feeds.

RESULTS

All three mydriatic regimens provided adequate pupillary dilation at 45 minutes, with dilation sustained at 60 minutes. There was a significant increase in mean blood pressure in the cyclopentolate 1% + phenylephrine 2.5% and the tropicamide 1% + phenylephrine 2.5% groups. Although there was no significant change of abdominal girth in any of the three groups, a total of eight patients developed intolerance to feeds; four (50%) of these infants were from the cyclopentolate 1% + phenylephrine 2.5% group.

CONCLUSION

The prepared combination of cyclopentolate 0.2% + phenylephrine 1% appears to be the mydriatic of choice for preterm infants with dark irides as it provided adequate pupillary dilation with the least systemic side effects.

SYSTEMIC MANIFESTATIONS IN RESPONSE TO MYDRIASIS AND PHYSICAL EXAMINATION DURING SCREENING FOR RETINOPATHY OF PREMATURITY

OBJECTIVE

To determine whether adverse effects manifested via vital sign changes during the screening examination for retinopathy of prematurity (ROP) are due to the pharmacologic properties of the eye drops or to physical manipulation of the eyes. The authors also investigated the relationship between distress during the screening process and the severity of prematurity of the infant.

DESIGN AND METHODS

A prospective observational study was designed that enrolled all infants either weighing < or =1500 g or who were < or =32 weeks gestational age at birth who were admitted to the neonatal intensive care unit (NICU) at Northwest Texas Hospital or Baptist St. Anthony's Hospital from June 2002 to February 2003. Thirty participants were enrolled in this study. Blood pressure, pulse, temperature, respiratory rate, and O2 saturation were recorded at different time intervals during the examination. Infants were excluded from the study if they were on the ventilator, considered acutely ill, born with significant birth defects, or currently taking inotropic drugs, or had received albuterol 2 hours before the examination.

RESULTS

Oxygen saturation and pulse rate following physical manipulation of the eyes significantly varied from baseline values and the values obtained during the three instillations of topical mydriatics. No significant changes in blood pressure, temperature, or respiratory rate from their respective baseline values were observed throughout the ROP screening examination. Gestational age of the infant did not correlate with level of distress during the examination.

CONCLUSION

Regardless of the severity of prematurity, infants seem to undergo significant distress during the eyelid speculum examination. Thus ophthalmologists should take into consideration the infant's discomfort caused by physical manipulation of the eyes and attempt to perform the examination as swiftly, yet safely, as possible using topical anesthetic.

Rétinopathie du prématuré : résultats de l’examen du fond d’œil chez 94 enfants à risque

PURPOSE

The purpose of this study was to evaluate the incidence and severity of retinopathy of prematurity (ROP) in infants of birth weight less than 1.500 g and/or under 32 weeks'gestation.

METHODS

Ninety-four preterm infants were examined following the Royal College of Ophthalmologists guidelines and retinopathy was graded using the International Classification of ROP. Screening limits were 1 500 g birth weight or 32 weeks'gestational age. Fundus examinations for ROP were performed at 5 weeks'chronological age from birth. Pupil dilation was obtained with instillation of 1% tropicamide three times at 15-minute intervals.

RESULTS

The 94 infants examined for ROP had a median gestational age of 292.3 weeks and a median birth weight of 1 110340 g. ROP was diagnosed in 21 of 94 subjects (22.3%) by fundus examination. ROP stage 3 developed in one preterm infant, ROP stage 2 developed in five preterm infants, and ROP stage 1 developed in 15 preterm infants. No premature babies developed stage 4 or stage 5 ROP. The disease regressed spontaneously in all cases and none of the infants required cryo/laser therapy. In the most premature infants, 23-26 weeks'gestation, 57% developed ROP and one developed severe ROP (stage 3). No disease more posterior to peripheral zone 2 was observed. The incidence of ROP was higher in infants exposed to greater than 21% oxygen (24.2%) than in infants who did not receive oxygen (17.8%). Oxygen, blood transfusion, and cardiopathy appear to be associated with an increased incidence of retinopathy of prematurity.

CONCLUSIONS

ROP continues to be a common problem associated with prematurity in France. This study found a similar incidence of prethreshold ROP when compared to recent studies. The data showed that blood transfusion and cardiopathy may play a role in the development of ROP in premature infants.

Combination cyclopentolate and phenylephrine for mydriasis in premature infants with heavily pigmented irides

PURPOSE

This study examined whether safe and effective mydriasis can be achieved in premature infants with heavily pigmented irides using combination cyclopentolate 0.2% and phenylephrine 1% eyedrops.

METHODS

A prospective, randomized double-blind study was performed to compare combination cyclopentolate 0.2% and phenylephrine 1% eye-drops with triple instillation of tropicamide 0.5% and phenylephrine 2.5%. Twenty-eight consecutive babies with dark irides and birthweight <1600 g referred for screening for retinopathy of prematurity comprised the study population. Infants' eyes were randomly dilated twice with both regimens within a 2-week period. Blood pressure, heart rate, and pupil size were measured.

RESULTS

Good mydriasis was achieved in both groups with no significant differences in pupil size or blood pressure (systolic, diastolic, or mean arterial pressures) over starting baseline values. Pulse rates decelerated below the baseline values in both groups, but these differences were not large.

CONCLUSION

The single combination eyedrop of cyclopentolate 0.2% and phenylephrine 1% is as effective and safe a mydriatic for infants with dark irides as both tropicamide 0.5% and phenylephrine 2.5%.

Pupillary diameter and reaction to light in preterm neonates

The pupil controls the amount of light entering the eye. We have examined both the time course for the development of the light reflex and pupil diameter before and after this event in 50 neonates. The pupillary light reflex was absent in all neonates of less than 30 weeks' gestational age, it gradually developed from this age and by 35 weeks it was present in all. Several possible mechanisms that may explain the onset of this reflex are considered. Before the onset of the pupil reflex mean horizontal pupillary diameter was 3.46 mm compared with 3.02 mm after the reflex development. We have estimated the amount of light reaching the retina (retinal irradiance) for preterm neonates and although it is less than that known to cause retinal damage in animals, further research is necessary to determine whether early light exposure has an adverse or beneficial effect on the immature visual system.