Fight for the eyesight of premature babies

Oxygen is the elixir of life, and this was brought home during the Covid-19 pandemic when millions of lives perished because of the worldwide scarcity of the much sought-after oxygen cylinders. However, it is not widely known that oxygen is also a double-edged sword. When given to yet-not-fully-developed babies born too soon, high-concentration oxygen may devastate their eyesight.

An estimated 18,000 babies thus go blind for life every year in India alone. Using unmonitored, high-concentration supplemental oxygen in newborn care units undoubtedly saves lives, but often at the cost of blindness. The blindness results from the consequences of scarring and unfettered growth of abnormal blood-supplying vessels in the immature retina. It is now known as retinopathy of prematurity (ROP).

Babies mature in the womb for 40 weeks before entering the world. The eye's light-sensitive layer, the retina, is fully matured only if the baby attains at least 2,000-gm weight. If born before 31 weeks, several vital organs, especially lungs and retina, are not fully developed. A vast swath of the retina remains without a blood supply, especially in babies weighing less than 1,250 gm.

Around the turn of the 20th century, doctors realised that babies born too soon could be saved if given oxygen. In the early 1940s, Dr Theodore Terry from Boston (USA) first flagged the issue of a visible white reflex due to massive scar tissue seen in the eyes weeks after birth of premature babies, all of whom weighed less than three pounds at birth. For several years, exposure to light was wrongly blamed.

It was a pathologist in London, Norman Ashton, who fortuitously discovered that the retina of the kitten till three weeks of birth was similar to that of a human baby born too soon. He created an ROP-like picture by first exposing these kittens to high-concentration oxygen and returning them to room air. Arnall Patz at Johns Hopkins was to discover almost simultaneously that if oxygen delivery in premature babies was monitored, they did not develop ROP.

According to Dr Sourabh Dutta, Professor at the Neonatology Department, PGI, Chandigarh, India is experiencing an epidemic of ROP-induced blindness due to increased survival of premature babies, unregulated oxygen use, lack of pulse oximeters and oxygen blenders in the newborn care units mushrooming all over urban India. Highly skilled manpower is required to care for these babies and counsel the parents. Although at-risk babies continue to be born, albeit in small numbers, in high-income countries of Europe, North America and Southeast Asia, hardly a baby goes blind from ROP because of the advanced infrastructure in the neonatal intensive care unit (NICU).

Almost four decades after what led to ROP was understood, experts reached a consensus on grading the stage and severity of ROP and developed guidelines for treating the immature retina in these babies. While many early-stage cases resolve without treatment, some babies may require laser therapy or injections into the eye of drugs to block the abnormal retinal vessel development. If treated appropriately, success rates exceed most medical procedures. This protocol has also become the most cost-effective procedure by saving sight for the rest of life.

Dr Joy Lawn from the London School of Hygiene and Tropical Medicine and colleagues estimated that nearly 15 million babies worldwide are born too soon (less than 37 weeks). With India topping the charts, almost eight million babies are born too soon in resource-limited middle- and low-income countries. Those born too soon in low-income countries with poor resources barely have any chance of survival.

Timely detection, staging and treatment within 48 hours of at-risk babies is the key to saving their sight. The American Academies of Paediatrics and Ophthalmology recommend screening babies born with a birth weight of less than 1,500 gm, gestational age of 30 weeks or less, or any newborn with a higher weight (up to 2,000 gm) who received oxygen even for a few days.

Dr Praveen Kumar, head of the Neonatology Department in PGI, however, recommends that Indian babies born before 34 weeks or weighing less than 2,000 gm or even higher if oxygen support is required must be screened for ROP. Starting at 28 days of age or discharge from NICU, whichever is earlier, the eye surgeon needs to monitor the newborn until the retina is fully matured. Training thousands of eye surgeons and equipping them with the necessary skills nationwide to screen and treat these tiny babies is a herculean task. Dr Subhadra Jalali in Hyderabad and Anand Vinekar in Bangalore, both PGI alumni, have devoted their careers to saving the right of sight of these hapless babies.

More than 50 years ago, Prof ON Bhakoo set up a modern neonatal intensive care unit (NICU) in the PGI, Chandigarh, and started training super specialists (DM) in neonatology. They were successful in saving the lives of very low birth weight babies. I remember Dr Anil Narang, who trained at Oxford and followed Professor Bhakoo, asking me the big question — who among us would undertake the onerous task of examining and treating those at risk of ROP in these tiny incubator-bound babies?

Dr Mangat Dogra, fresh from his training in the US, volunteered. As they say, the rest is history. Applying a cold probe at -80° Celsius (cryotherapy) to the retina that lacked blood supply was the standard of care back then if these babies had to have any eyesight in their lifetime. The babies had to be put under general anaesthesia. I remember the long hours he spent in NICU, examining babies, selecting those requiring treatment, and chasing anaesthetists, who, in those days, had little experience in giving anaesthesia to 1,000-1,200-gm babies. He would regularly share the day's story with me. I remember the pride on his face, a million-watt smile, announcing that the baby would see as the ROP had regressed.

Over the decades, cryotherapy was supplanted with lasers and injections that do not require anaesthesia. In the last 35 years, Dr Dogra has treated the retinas of hundreds of premature babies and trained many ophthalmologists across India, including Anand. Happily, many of the same teeny-weeny babies he saved the sight are having babies with normal sight.