Reduction in mydriatic drop size in premature infants.

Abstract

In a prospective study of 26 premature infants, 5 ,l microdrops were compared with standard 26 ul eye drops of cyclopentolate 0-5% and phenylephrine 2 5%. There was no statistical difference in pupil dilatation. The 5 gl microdrops have potentially fewer adverse effects in premature infants. (BrJf Ophthalmol 1993; 77: 364-365) Systemic toxicity from DiscussionThe volume of an eye drop from a minim is 26 /u16 which is greatly in excess of the adult precorneal tear film volume of 7 ul.7 Eighty per cent of standard drops may be lost in the first 15-30 seconds via the nasolacrimal duct, conjunctival blood vessels, or spillage onto the skin. Systemic absorption is directly into the circulation from the conjunctival and nasal mucosa without first pass metabolism in the liver. Therefore systemically absorbed eye drops are more like intravenous agents than oral ones.7There was no statistically significant difference in pupil dilatation in this study between the smaller 5 ul drop size and the conventional 26 ul drop size. Equal pupil dilatation has been demonstrated with 8 ,ul and 30 ul drops of phenylephrine in neonates but the pupil size was only 4-86 mm and 4-57 mm respectively.8 The pupil diameter was larger in this study which is compatible with the results of Carpel and Kalina who showed there was an additional effect in premature infants when cyclopentolate was added.9 In adults reduction in drop size of phenylephrine 10% and tropicamide 1% produces adequate mydriasis.6Brown et al have shown that drop size can be reduced by designing a bottle with a narrower outlet.'0 The systemic absorption is less with a smaller than a larger drop volume.8 Infants in particular may be more likely to absorb eye drops systemically as the tear volume is small and the drops are instilled supine so that spillage onto the skin may be less. " The risk oftoxicity may also be increased because of low body mass and the immaturity of the cardiovascular and nervous systems.4 Cyclopentolate in adults and children may cause psychosis, behavioural disturbance, ataxia, agitation, fits, and gastrointestinal upset.'2 Preterm twins developed gastrointestinal side effects from cyclopentolate 1%, and abdominal distension and increased gastric aspirate was reported in 50 preterm infants examined for retinopathy of prematurity.512 There are many reports of cardiovascular adverse effects from phenylephrine.' 2 Raised blood pressure has been observed in preterm infants after dilatation with 2 5% phenylephrine and this potentially increases the risk of intraventricular haemorrhage.4The risk of adverse systemic effects from eye drops is well recognised and as more and more premature babies are being examined it would be better medical practice not to use over five times more medication than is required.

The influence of drop size of cyclopentolate, phenylephrine and tropicamide on pupil dilatation and systemic side effects in infants

“…In this study, there was no significant difference in pupil dilatation between the smaller drop size and the standard drop size of cyclopentolate 1% and phenylephrine 10% in infants. In a previous report, equal pupil dilatation has been demonstrated with 5 p1 and 26 p1 drops of cyclopentolate 0.5% and phenylephrine 2.5% in premature infants (Wheatcroft 1993). However, one microdrop of tropicamide 0.5% gave inadequate pupil dilatation.…”

Prevalência de retinopatia da prematuridade em prematuros atendidos no período de 1992-1999 em Joinville (SC): avaliação de riscos associados - "screening"

“…Alguns autores defendem tropicamida 1% outros usam ciclopentolato diluído, fenilefrina a 0,25% com tropicamda 0,5% (12)(13)(14)(22)(23)(24) . Isto é importante em cidades onde as distâncias são grandes e o oftalmologista não tem horário certo de chegada na Unidade.…”

“…Quando havia dificuldade na dilatação, foi considerado sinal plus (11) e repetia-se o exame na semana seguinte. Com essas medidas de segurança usou-se um só tipo de colírio midriático diferente do que se preconiza na literatura (12)(13)(14) . O exame de mapeamento de retina era realizado com oftalmoscópio indireto, lente de 20 dioptrias, blefarostato e depressor escleral, quando necessário.…”

Systemic effects of screening for retinopathy of prematurity.

“…The mean ,gen saturation increase in systolic reading in this study was the change in 5-3 mm Hg and in diastolic 6 mm Hg at 15 :amination was minutes, although there was a large variation in aalysis failed to response. Lynch et al 17 and Wheatcroft et al 18 nce in blood suggest reducing the drop size to avoid side…”