On completion of 15 years of the retinopathy of prematurity (ROP) screening programme, LV Prasad Eye Institute (LVPEI) rededicated its teams in Hyderabad, Bhubaneshwar, Vijayawada and Visakhapatnam to further expand the newborn eye screening programme and spread its reach to every baby to enable them achieve their ‘Right to Sight’.
M Neelam Kachhap spoke to Dr Subhadra Jalali, Associate Director, Consultant, Smt. Kannuri Santamma Retina Vitreous Service and Jasti V Ramanamma Children’s Eye Care Centre, LV Prasad Eye Institute, Hyderabad about the issues related to the disease
What are the causes and risk factors for ROP?
There are a number of causes and risk factors related to ROP such as prematurity, birth weight, oxygen fluctuation, sepsis, anaemia, ventilation, multiple pregnancy, diabetic mother with premature baby, blood transfusions in baby, apnoeic spells etc. Bigger and heavier weight babies in India and the developing world get ROP, and more severe ROP as compared to Western countries. These are due to differences in maternal and postnatal care factors. (data published by Clare Gilbert in Paediatrics)
What is the pathophysiology of the disease?
Avascular and immature retina at birth of a premature baby is vulnerable to external insults of post natal care as well as postnatal and prenatal growth. Failure or derangement of vasculogenesis and angiogenesis of retinal vessels lead to accelerated ischaemic events in retina, manifesting as dilatation and tortuosity of vessels, vitreous haemorrhage and tractional and exudative retinal detachments. These are mediated by increased levels of vasculoendothelial growth factors (VEGF) and reduced levels of insulin-like growth factors (IGF) in the growing eye outside the womb.
Is this a sudden onset disease or is it gradual vision loss?
In the acute phase, it develops within two to four weeks of birth and is called as aggressive posterior ROP. This is seen in most tiny and most sick babies, especially with poor weight gain. This is supposed to be due to failure of vasculogenesis. In others it progresses from three to eight weeks or so of birth rapidly but not as aggressive as first category, and is due to failure of angiogenesis and often leads to irreversible retinal detachment in 9-15 per cent babies. In some babies, disease is mild and regresses on its own, generally around expected date of delivery that is by 40-42 weeks post-menstrual age. So, in most cases there is an optimal two weeks or so of window period where the disease can be assessed and treated well so that any adverse effects on the growing eye can be prevented. It is, hence, a rapidly progressive condition and is treated as a medical emergency- once vision threatening stage is detected it should be treated within 72 hours. As the child grows, in chronic phases slow and progressive vision loss can occur due to amblyopia, refractive problems, glaucoma, cataract, late-onset retinal detachments, late-onset vitreous haemorrhage, squint etc.
A premature baby requires oxygen how then can this be controlled so that ROP does not happen?
Fluctuating and intermittent oxygen administration, administration of unblended oxygen or unmonitored oxygen are all very bad practice oxygen strategies. Slow and steady weaning of oxygen is recommended. Oxygen monitoring by pulse oxymeter (should be maintained between 85-93 per cent or so) and blood gas estimations whenever needed are strongly recommended. Proper use of continuous positive airway pressure (CPAP) strategies is recommended. For best practice care, doctors can refer to National Neonatology Forum (NNF) clinical practice guidelines (CPG) 2010 available onthe NNF website of India. Oxygen requirements can be reduced by antenatal steroids to the mother. Oxygen need will also reduce by strict attention to asepsis and nutrition of the baby. However, one must remember that oxygen strategies only modify the ROP process. Babies who are premature and never received oxygen can still get severe ROP and vision loss.
How is ROP detected? Who can do this diagnosis?
ROP is easily detected by periodic fundoscopy starting from 20-30 days of birth. Any person trained in neonatal fundoscopy can screen for ROP. Main instrument used is the binocular indirect ophthalmoscope.
Alternatively, digital fundus camera can be used in some stages of the disease. Most cases are detected by eye specialists. However, there are some attempts to detect ROP by trained technicians using telemedicine techniques.
Are there different types of ROP?
Major differences are in vasculogenic ROP and angiogenic ROP as mentioned earlier. They differ in onset, severity, rapidity of worsening, resistance to treatment, outcomes etc.
How are these treated?
Standard of care is laser photocoagulation of the avascular retina to remove the source of abnormal (VEGF) secretion. The outcomes of the therapy are very good if screening and laser are done earlier in the progressive disease than later. Alternatively, cryopexy is used though results are less optimal than laser and is more painful with more side effects. Recently, anti-VEGF injections are considered as rescue therapy or as monotherapy but these are as off-label usage. These injections are still under research considerations for dosage and the short-term and long-term ocular and systemic adverse effects.
Can vision be restored 100 per cent?
Vision loss can be prevented and the macular structure can be preserved to what the child was born with, in more than 90 per cent babies if detected and treated on time. The ROP treatment is directed to the retina which is only one of the components of a good vision. Other components include development, cognition, attention, medications for epilepsy etc., all of which can affect visual performance.
Some premature babies may not get completely normal vision due to these neuro-developmental issues even though the macula is well preserved with ROP treatment. Most premature babies need glasses for getting best visual outcomes.
What is the prevalence of ROP in India?
ROP affects about 30-50 per cent of premature babies in India. Severe vision threatening ROP that needs treatment occurs in about 20 per cent of these.
About 16-20 per cent of severe ROP is seen in large and more mature babies in India than in Western populations.
What are the steps that neonatal intensive-care units (NICUs) should take to prevent ROP?
Follow all the antenatal and postnatal good CPG as outlined in the India NNF guidelines 2010 (available on their website). These include practices before and at time of delivery, first golden hour practices, baby transport, oxygen, lungs management, asepsis, nutrition, transfusion etc. Always get every pre-term baby Retinal examination between 20-30 days of life and ensure that this importance is understood by all staff and parents- put up awareness charts in waiting areas of NICU and make a mandatory column in discharge summary of all NICU and sick newborn care unit (SNCU) graduates.
In follow-up ensure that timely ROP screening and its follow-up has been completed. These practices reduce the prevalence of ROP and severe ROP and also reduce the chances of blindness. However, ROP cannot be completely eliminated and hence timely ROP screening is also essential.
mneelam.kachhap@expressindia.com