Pilot study of the systemic effects of three different screening methods used for retinopathy of prematurity

Abstract

Purpose

This pilot study compared the physiological and behavioural changes in premature infants undergoing three different methods of screening for retinopathy of prematurity (ROP).

Study Design

Prospective randomized cross-over pilot study.

Subjects and Methods

Fifteen premature infants requiring screening for ROP were recruited, and physiological and behavioural responses produced by three different methods of screening were compared. The screening methods employed a RetCam 120 and an indirect ophthalmoscope with and without an eyelid speculum. Physiological indices (change in pulse, mean blood pressure and oxygen saturation) and facial responses to pain (brow bulge, eye squeeze, nasolabial fold, mouth opening and the presence of cry) were recorded at five points: before, during and immediately after screening and 10 and 30 min after examination.

Results

Screening with the RetCam 120 and the indirect ophthalmoscope with a speculum both caused a greater change in pulse and mean blood pressure and an increase in facial responses to pain during and immediately after screening as compared to the indirect ophthalmoscope without the speculum. RetCam 120 screening caused greater desaturation than the other methods.

Conclusions

Although this was a small sample which limits absolute conclusions, the study showed that screening using a RetCam or a speculum and indirect ophthalmoscope caused more stress to the infant, as indicated by physiological and behavioural changes, than simply screening using an indirect ophthalmoscope without a speculum. These effects should be considered when deciding on the appropriate screening method for examining particularly sick infants.

Introduction

Retinopathy of prematurity (ROP) is a major cause of blindness in premature babies and is routinely screened for in the susceptible population. With continued improvements in neonatal care, there is increased survival of shorter gestation and lower birth weight infants who require screening, although recent reports have suggested a decreasing incidence and severity of ROP [1]. In the developed world, it is a disease of the most immature and unwell infants, and considerably more infants need to be screened than the small numbers requiring treatment. It has been estimated that about 8200 infants require screening each year in the UK with less than 2% requiring treatment [2]. The EPICure [3] study of extremely premature babies born before 26 weeks completed gestation, in the UK and the Republic of Ireland, found that 45 (14%) received treatment for ROP. The aims of screening as detailed in the UK current guidelines [4] are ‘to identify ROP which has the potential to reach stage 3 and severe ROP (stage 3) which may require treatment’. It is important while examining these fragile infants, for a condition that rarely requires treatment, not to stress or harm them. Screening examinations are recognised to be stressful for these infants [5].

Screening is usually undertaken using indirect ophthalmoscopy, and an eyelid speculum and scleral indentor may also be used although these are not mandatory. More recently, in addition to screening with an indirect ophthalmoscope, some units now have available the RetCam imaging system to evaluate ROP [6]. We have been using RetCams and indirect ophthalmoscopy for ROP screening, and our impression had been that the RetCam was a more distressing method of examination for the infant. To investigate this issue, we conducted a pilot prospective randomized cross-over study to identify, quantify and compare the distress produced in 15 premature babies during three different ROP screening methods. Behavioural observations and physiological parameters were compared in this study, which have been shown to correlate with neonatal pain and/or distress during various painful interventions, such as heel lance and circumcision [7], [8].