Systemic response to mydriatic eyedrops in neonates: mydriatics in neonates

Early phase of pupil dilation is mediated by the peripheral parasympathetic pathway

Pupil diameter fluctuates in association with changes in brain states induced by the neuromodulator systems. However, it remains unclear how the neuromodulator systems control the activity of the iris sphincter (constrictor) and dilator muscles to change the pupil size. The present study compared temporal patterns of pupil dilation during movement when each muscle was pharmacologically manipulated in the human eye. When the iris sphincter muscle was blocked with tropicamide, the latency of pupil dilation was delayed and the magnitude of pupil dilation was reduced during movement. In contrast, when the iris dilator muscle was continuously stimulated with phenylephrine, the latency and magnitude of rapid pupil dilation did not differ from the untreated control eye, but sustained pupil dilation was reduced until the end of movement. These results suggest that the iris sphincter muscle, which is under the control of the parasympathetic pathway, is quickly modulated by the neuromodulator system and plays a major role in rapid pupil dilation. However, the iris dilator muscle receives signals from the neuromodulator system with a slow latency and is involved in maintaining sustained pupil dilation.

NEW & NOTEWORTHY By pharmacologically manipulating the pupil dilator and constrictor muscles of human eye separately, we found that the pupil constrictor muscle is a primary controller of rapid pupil dilation upon brain arousal. However, the pupil dilator muscle, which is innervated by the sympathetic nervous system and is generally considered as a major regulator of pupil dilation, is not involved in rapid pupil dilation, but was involved in long-lasting pupil dilation.

Effects and Side Effects of Mydriatic Eyedrops in Neonates

The pupils of neonates and premature infants often need to be dilated for retinal examination. The drops used for this purpose have some known side effects. This study investigated the effects and side effects of these drops. In this prospective randomized study, 80 healthy neonates were randomly assigned to eight groups. In Group A 1% cyclopentolate was used; in Group B 1% tropicamide; in Group C 2.5% phenylephrine; in Group D 1% cyclopentolate and 1% tropicamide; in Group E 2.5% phenylephrine and 1% tropicamide; in Group F 0.5% cyclopentolate, 0.5% tropicamide and 2.5% phenylephrine; in Group G 1% cyclopentolate and 2.5% phenylephrine and in Group H 0.9% NaCl. Heart rate, systolic and diastolic blood pressures were recorded before, and 5, 10, 15, 30, 45, 60 minutes after instillation of the drops. Pupillary size was measured at baseline, 30 and 60 minutes. To stimulate the conditions of indirect ophthalmoscopic examination, the pupil sizes were measured under the intense beam of a halogen light. The results were analyzed statistically. Maximum side effects were seen in group C; the safest was group B and maximum mydriasis was achieved in group F.

The Efficacy of 2.5% Phenylephrine and Flurbiprofen Combined in Inducing and Maintaining Pupillary Dilatation during Cataract Surgery

Purpose

To evaluate the effectiveness of phenylephrine 2.5% and flurbiprofen 0.03% combined in inducing and maintaining mydriasis during extracapsular cataract extraction (ECCE).

Methods

One hundred patients undergoing ECCE + intraocular lens (IOL) implantation were randomly divided into four groups. The first group was given phenylphrine 10%, the second group phenylephrine 10% + flurbiprofen, the third group phenylephrine 2.5% and fourth group phenylephrine 2.5% + flurbiprofen. Cyclopentolate 1% was used in all patients. Phenylephrine and cyclopentolate were instilled preoperatively four times during 1 hour and flurbiprofen was given four times the day before surgery and twice with an hour's interval before operation. Pre-operative and post-cortex aspiration horizontal pupil diameters were measured with callipers viewed through the operating microscope.

Results

Pupil diameters in pre-operative and post-cortex aspiration were no different in the 2.5% and 10% phenylephrine groups (p>0.05). Both diameters were larger and pupillary constriction was smaller in the flurbiprofen groups (p<0.05).

Conclusions

2.5% phenylephrine was as effective as 10% phenylephrine, with and without flurbiprofen, in inducing and maintaining pupil dilatation during ECCE surgery.

A 5-Minute Interval between Two Dilating Eye Drops Increases Their Effect

PURPOSE

Patients are usually advised to wait 5 minutes between eye drops. This delay supposedly allows the first drop not to be washed out by the second one, thereby increasing the combined effect. However, in the only experimental study conducted in humans on the concurrent administration of two different eye drops, the authors concluded that a 10-minute time interval between eye drops did not increase their combined effect. Our study was designed to address this puzzling observation.

METHODS

Using digital photographs shot in photopic conditions in 40 eyes of 20 healthy volunteers, we compared relative pupil surface (i.e., pupil to iris surface area ratios) before and after the administration of one drop of 10% phenylephrine and one drop of 0.5% tropicamide either immediately or after a 5-minute time interval.

RESULTS

Waiting 5 minutes yielded a 5.6% relative pupil surface gain (observer 1: P = .003, observer 2: P = .005) indicating an additional combined effect with a 5-minute time interval.

CONCLUSIONS

These results show a detectable additive effect that is probably the result of methodological refinements including the challenging of the mydriasis by photopic conditions and the use of pupil and iris surface areas, which may show differences that would be undetectable in terms of diameter.

Combination of 5% phenylephrine and 0.5% tropicamide eyedrops for pupil dilation in neonates is twice as effective as 0.5% tropicamide eyedrops alone

PURPOSE

Comparison of the efficacy of tropicamide eyedrops to the combination of 0.5% tropicamide and 5% phenylephrine eyedrops in order to achieve a proper dilation in premature infants undergoing screening for retinopathy of prematurity.

METHODS

A prospective, randomized, double-blind study was conducted to compare the efficacy of two mydriatic regimens: one regimen consisting of three drops of 0.5% tropicamide (TTT regimen), the other regimen consisting of one drop of 5% phenylephrine and two drops of 0.5% tropicamide (PTT regimen). Thirty premature infants were enrolled and received both mydriatic regimens: one regimen in each eye. Outcomes were pupil dilation evaluated by the percentage of pupil diameter over cornea diameter, the percentage of pupil surface over cornea surface and the quality of the eye fundus examination.

RESULTS

The percentage of pupil diameter over cornea diameter was 47.3% (±8.7) with the TTT regimen and 65.9% (±8.8) with the PTT regimen (p < 0.0001). The percentage of pupil surface over cornea surface was 23.1% (±8.3) with the TTT regimen and 43.8% (±7.3) with the PTT regimen (p < 0.0001). Thus, the pupil surface area was 1.9 times greater with the PTT than with the TTT regimen. Visualization of the retinal periphery was possible for 30 of 30 eyes dilated with the PTT regimen and for 16 of 30 eyes dilated with the TTT regimen (p < 0.0001).

CONCLUSION

The dilated pupil surface area for the combination of 5% phenylephrine and 0.5% tropicamide was almost twice that for 0.5% tropicamide eyedrops alone and provided significantly superior quality of the eye fundus examination.

[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.

Lack of efficacy of dilated screening for retinoblastoma

PURPOSE

To assess red reflex testing of the pharmacologically dilated pupil in screening for retinoblastoma.

PATIENTS AND METHODS

Children with a family history of retinoblastoma or a history of treated retinoblastoma who were admitted to our institution for examination using anesthesia during a 3-month period underwent red reflex testing of the pharmacologically dilated pupil in a masked fashion. Red reflexes were classified as normal (unremarkable), abnormal (in brightness or color), or absent (no reflex, black pupil). The results of the screenings were later compared with actual retinal findings.

RESULTS

Red reflex testing of the dilated pupil failed to identify all 13 eyes that harbored retinoblastoma lesions (all 13 were classified as normal). The 3 eyes that were identified as having abnormal red reflexes had neither disease nor significant refractive error.

CONCLUSION

Red reflex testing of the dilated pupil is a poor screening technique for retinoblastoma.

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.

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%.

Utility of pupillary dilation for detecting leukocoria in patients with retinoblastoma

In the United States, 50% of all retinoblastoma cases are diagnosed after the observation of leukocoria by a family member or primary care physician. However, leukocoria produced by retinoblastoma lesions can often be missed by direct ophthalmoscopic examination through an undilated pupil. The purpose of this study is to demonstrate the utility of pupillary dilation for the detection of leukocoria in suspected cases. Seven patients (10 eyes), aged 2 days to 20 months, with retinoblastoma were examined for leukocoria using a direct ophthalmoscope with the pupils first undilated and then after pharmacologic dilation with 0.5% cyclopentolate and 2.5% phenylephrine. Leukocoria was detected by direct ophthalmoscopy on undilated examination in 3 of 10 eyes (30%). In contrast, leukocoria was observed after pupillary dilation in 10 of 10 eyes (100%). The retinoblastoma lesions, from 2 to 10 mm in diameter, were located within the posterior 45 degrees of the retina. Pupillary dilation is a safe and effective tool that can enhance the ability of the examiner to detect leukocoria. Dilation may afford early diagnosis and treatment, and therefore should be considered on patients in whom the diagnosis of retinoblastoma is entertained.

A comparative study of the efficacy of 2.5% phenylephrine and 10% phenylephrine in pre-operative mydriasis for routine cataract surgery

It is common practice in many ophthalmic units to administer multiple applications of 10% phenylephrine in combination with an anti-cholinergic agent to ensure adequate pupil mydriasis prior to routine cataract surgery. Phenylephrine is a pure alpha-1 adrenoreceptor agonist known to produce marked systemic vasoconstriction and associated hypertension with occasional profound reflex bradycardia. Many reviews have suggested caution in the use of 10% phenylephrine in the elderly or hypertensive patient. In a prospective, randomised trial we have assessed pupil dilation comparing the efficacy of 10% phenylephrine (53 patients) versus 2.5% phenylephrine (62 patients). When administered in conjunction with 1% cyclopentolate four times over 1 hour pre-operatively, 2.5% phenylephrine was found to be as effective as 10% phenylephrine in the initiation and maintenance of mydriasis during both extracapsular and phacoemulsification cataract extraction.

A mydriatic eye-drop combination without systemic effects for premature infants: a prospective double-blind study

Eye drops used for diagnostic mydriasis may produce systemic side effects in preterm infants. Studies on the pupil dilating and systemic effect of various mydriatic agents yielded conflicting results. We conducted a prospective randomized double-blind study on the systemic effect of two mydriatic eye-drop combinations. Thirty-nine preterm infants were randomly assigned to two groups. An eye-drop combination of 2.5% phenylephrine and 0.5% tropicamide (group D) was compared with the combination of 0.5% cyclopentolate and 0.5% tropicamide (group F). Either eye-drop combination was followed by 0.5% tropicamide given 20 minutes later. Heart rate (HR) and the systolic, mean, and diastolic blood pressure (BP) were recorded before and after eye-drop instillation and after ophthalmoscopy. A control session with NaCl eye drops was added for each infant. A significant increase of BP and HR peak values was observed within 7 to 10 minutes after the cyclopentolate/tropicamide combination only. On the other hand, the mydriatic effect of the phenylephrine/tropicamide combination was significantly superior to that of the cyclopentolate/tropicamide combination. We recommend the combination of 2.5% phenylephrine and 0.5% tropicamide to achieve a sufficient diagnostic mydriasis without systemic side effects in preterm infants.

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

We conducted a randomized, masked study of pupillary dilating capabilities and associated cardiovascular effects of three solutions. Thirty-four babies less than 1500 grams at birth were studied at six to eight weeks. Group A (n = 10) received phenylephrine (PE) 2.5% and tropicamide 1.0%; Group B (n = 10) PE 2.5%, tropicamide 0.5%, and cyclopentolate 0.5%, Group C (n = 10) PE 1.0% and tropicamide 1.0%; Group D (n = 4) saline 0.9%. One drop was placed in each eye and repeated five minutes later. Pupillary dilation was measured with a metric ruler by direct observation at one hour. Blood pressure (BP) and heart rate (HR) were monitored, using an oscillometer, immediately prior to the instillation of the drops and at five-minute intervals, for 60 minutes. BP and HR increased transiently in all groups receiving mydriatics but returned to baseline values in 25 minutes. This increase was significant in Groups A and B (2.5% PE: p less than 0.02). Group D (saline) showed no change in BP or HR. Postdrop pupillary size was largest in Group A but the differences were not significant. On exposure to bright light, the pupillary size in Group C was significantly smaller than Groups A or B (7.35 +/- 0.59 mm, 7.23 +/- 0.38 mm and 6.75 +/- 0.57 mm in Groups A, B and C, p less than .01). Nevertheless, dilation was sufficient to allow appropriate examination in all infants (pupillary diameter greater than 6.0 mm). Solutions containing 2.5% PE are most effective for use in LBW infants, but produce cardiovascular effects. Solutions containing 1% PE provide adequate dilation with minimum cardiovascular effects.

A cross-over study of the cycloplegic effects of a single topical application of cyclopentolate-phenylephrine and routine atropinization for 3.5 days

Static refraction in children after the topical instillation of atropine twice a day during 3.5 days was compared with the refraction after a single instillation of one drop of 0.85% cyclopentolate + 1.5% phenylephrine in a randomized cross-over study. Atropine eye drops were applied by the parents at home, while the combination drop was applied by personnel at the eye clinic. Refraction was determined by retinoscopy in 40 children (3-6 years) in a single blind manner. No statistically significant difference in cycloplegic effect was found between the 2 methods. The results imply that in clinical practice a single instillation of a combination of 0.85% cyclopentolate and 1.5% phenylephrine can be substituted for conventional "full" atropinization during 3.5 days.

A comparison of mydriatic eyedrops in low-weight infants

The pupils of neonates often need to be dilated to examine the retina for retinopathy of prematurity and other disorders. It is known that low-weight infants (less than 1600 grams) are susceptible to systemic hypertension when 10% or 2.5% phenylephrine eye drops are used. To find the safest and best commercially available mydriatic agent in neonates, 30 low-weight infants were divided evenly into three groups. The drops tested were cyclopentolate 0.5% alone, cyclopentolate 0.5% plus mydriacyl 0.5%, and a combination drop of phenylephrine 1% and cyclopentolate 0.2%. There was no clinically significant effect of any of the drops on systolic blood pressure or pulse rate. The cyclopentolate and phenylephrine combination dilated the pupils by a mean of 2.8 mm which was statistically greater than the other groups (P less than 0.01) and had a longer duration of maximal dilation than the other drops (P less than 0.05).

Preschool vision screening for amblyopia and strabismus. Programs, methods, guidelines, 1983

Amblyopia and strabismus, which afflict at least 5% of children, require treatment early in life for best visual results. At present, many such children are treated late or not at all. Mass screening at preschool age, and perhaps ultimately of infants, appears the only viable solution to this problem. To ascertain the present status of preschool screening in the United States, on-site visits, mail questionnaires and telephone interviews were used to study existing preschool vision screening programs at the federal, state and private organization levels. We estimate that, at most, 21% of preschool children receive any form of vision screening. Only two states, Michigan and Minnesota, have legislated requirements for such screening. Several organizations have attempted to establish screening guidelines, with suggestions of specific test and referral criteria. These guidelines are reviewed. The guidelines are of particular interest because screening programs following them typically indicate far lower prevalence rates than most studies indicate actually exist, suggesting that the guidelines result in underreferrals. In order to assess this matter, vision screening methods appropriate for preschoolers or infants, based on current evidence, are reviewed. Stereoscopic testing, utilizing a random dot stereogram format, appears the best instrument available for amblyopia and strabismus screening, but large scale comparative studies of the different test methods are needed to arrive at a final determination. Suggestions are made for the physician interested in initiating preschool vision screening programs.

Ophthalmological examination of the infant. Developmental aspects

In recent years, the ophthalmic examination of infants has been of increasing interest to both clinicians and vision researchers. Clinicians have documented a greater risk of retinopathy, strabismus and amblyopia in premature infants, especially those of low birthweight. In addition to the external and retinal examination of the infant eye, a number of clinical tests can help the ophthalmologist to detect visual dysfunction through the evaluation of pupillary responses and ocular motility. Recently, the development of objective techniques (optokinetic nystagmus, forced choice preferential looking, and visually evoked potentials) have not only aided in the detection of ophthalmic disorders in infants; they have contributed to useful definitions of "normal" vision at various ages and to the understanding of factors that influence the pre- and post-gestational development of visual function.

Systemic effects of mydriatics in low weight infants

Two-and-a-half percent phenylephrine eye drops were used in combination with 0.5% tropicamide for routine pupillary dilation in 10 low weight infants. Significant systolic blood pressure elevation was noted in eight of 10 infants. A matched control group dilated with cycloplegics alone did not show a significant rise in systolic blood pressure. The mean change in pupillary dilation in the study group was 3.9 mm compared with 3.1 mm in the control group. This difference is not statistically significant. We therefore recommend that cycloplegic agents alone be used for pupillary dilation in these high risk infants.

Effect of mydriatics on blood pressure in premature infants

Systolic blood pressure (SBP) was measured by doppler methods at 5, 15, 30, 45, and 60 minutes in 52 premature infants after triple instillation of aqueous phenylephrine 2.5% and tropicamide 1.0%. Systolic blood pressures were insignificantly increased 3.9 +/- 2.0 mm Hg (mean +/- S.E.) at 15 minutes when compared with controls matched for initial blood pressure, birth weights and age at examination. Though a 964 gm, 28-week Caucasian male with retinopathy of prematurity had been uneventfully dilated, pupillary dilatation one week later with triple instillations of phenylephrine 2.5% and tropicamide 1.07% was accompanied by an acute increase in systolic blood pressure to 108 mm Hg at 15 minutes, which remained elevated for 150 minutes. A new lower dose, single instillation mydriatic became available whose final concentration was phenylephrine 2.5%, tropicamide 0.5% and cyclogyl 0.5%. A single drop was found to produce mydriasis equal to the triple instillation regime. The single administration produced no significant effect on systolic blood pressure in 30 low birth weight infants (birth weight less than 1750 gm) when compared with balanced salt solution (placebo) in a randomized, double--masked study. Mechanisms of acute hypertension after topical mydriasis are discussed.

The problem of cycloplegia in the pediatric age group: a combination formula for refraction

Cycloplegic refraction and indirect ophthalmoscopy are essential to evaluation of the pediatric patient. Unfortunately, along with this practice occur the attendant risks of toxicity and the unpleasantness of instillation. The literature that documents the development of cycloplegic agents is often contradictory regarding efficacy and side effects. It is presented for perspective. We have found that efficacy and discomfort are inseparable; however, as with efficacy and toxicity they are directly related to the concentration used. The case is therefore made to use each agent in its minimal effective concentration and thereby minimize both discomfort and toxicity. Our combination of 1.3% cyclogyl, .167% mydriacil, and 1.6% phenylephrine accomplishes effective cycloplegia for refraction and indirect ophthalmoscopy, has a rapid onset and short duration, works reliably in dark irides, is accomplished in a single encounter with the patient, and exhibits none of the side effects of the individual agents in our series.