Retinopathy of prematurity (ROP)

Published on 03/06/2015 by admin

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CHAPTER 18 Retinopathy of prematurity (ROP)

Mark Davies, Garry Inglis

• The strongest risk factors for ROP are gestation and birth weight. The majority of significant ROP occurs in babies born at less than 28 weeks gestation.

• The association between ROP and oxygen therapy is well documented.

• Many with significant ROP also have chronic lung disease.

Babies at high risk for ROP are examined by an ophthalmologist to screen for the disorder.

• The most commonly used criteria for ROP screening are birth weight <1500 g or gestation at birth <32 weeks (as is done in our unit).

• Some units will include slightly bigger or mature babies if they have required significant oxygen supplementation or have otherwise been significantly unwell.

• Screening should begin at around 31 weeks postmenstrual age or 4 weeks of age.

• Frequency of re-examination will depend upon the findings.

Management

ROP is described according to the retinal zone involved (Zones 1–3), the stage of disease (Stages 1–5), the extent of disease (in clock hours) and whether there is ‘plus’ disease present.

• In most babies the retina will vascularise progressively from posterior (Zone 1) to anterior (Zone 3) without the need for intervention.

• In a small number, usually those with Stage 3 or greater disease (although the decision will depend on factors such as how aggressive the disease is and will obviously rest with the ophthalmologist), the retinopathy will be treated in an attempt to arrest disease progression and preserve as much functional vision as possible.

• Treatment for ‘threshold’ retinopathy will usually consist of photocoagulation (laser).

Less commonly, cryotherapy is used.

• For more advanced disease, treatment may include a scleral buckle procedure or vitrectomy — in reality these are rarely required.

Laser therapy for ROP

Laser may be done under local anaesthetic, general anaesthetic, sedation, or a combination of these. The specific procedure will vary by unit and ophthalmologist but is usually done in the intensive care nursery. A description of the procedure as performed in our unit is provided below.

Suggested laser therapy procedure

The laser treatment is usually done in the intensive care nursery. The infants with severe ROP requiring laser treatment are often babies who were very small and/or very preterm who have had a stormy neonatal course. Most will have, or have had, significant chronic lung disease (CLD).

The ophthalmologist usually requires:

• goggles for the laser operator and all staff working in the same room

• a small eye-speculum pack

• various eye drops and treatments:

— amethocaine eye drops

— cyclopentolate 0.2% / phenylephrine 1% eye drops for pupil dilation

— balanced salt solution (BSS) — this is not the same as Normal saline, Nsaline (0.9%)

— dexamethasone 1 mg/mL (Maxidex 0.1%)

— dorzolamide HCl 2% 20 mg/mL (Trusopt)

— chloramphenicol ointment (Chlorsig).

Once it is confirmed that the ophthalmologist is actually coming to do the procedure:

• obtain venous access prior to intubation

• give the usual sedation (see pages 29 and 81) plus vecuronium (0.1 mg/kg) for intubation

• intubate and ventilate just ahead of time

• dilate pupils 30 minutes prior to laser starting

• position baby supine with the head towards the foot of the bed (i.e. the baby’s head pointing towards the middle of the room)

• when the ophthalmologist arrives, ensure the baby is sedated and paralysed — e.g. morphine (0.1–0.15 mg/kg) and midazolam (0.1–0.15 mg/kg) and vecuronium (0.1 mg/kg) or pancuronium (0.1 mg/kg).

A neonatologist or other member of the neonatal medical staff stays close by during the entire procedure.

Repeat doses of muscle relaxant may be required.

Monitor the baby’s heart rate for evidence of inadequate analgesia.

The baby is usually ventilated overnight and extubated the next morning, if the ventilation has not exacerbated the CLD too much.

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