It should have been a very joyous occasion to have a new addition to your family, but instead you may have worries and doubts as you have had a prematurely born baby. Moreover you may have also been told that your baby has Retinopathy of Prematurity, a potentially sight threatening condition. I hope that this article explains and clears your fears and doubts about the condition.
Understanding the eye
Firstly, in a normal eye, the light passes through the clear part of the eye (cornea) to reach the film (retina) in the back of the eye through the lens, like in a standard still camera. The retina is a sensitive and complex layer, which converts the light into nerve impulses that are transferred via the optic nerve to the brain, which enables us to see. If the retina is not fully developed then the brain cannot be stimulated to see images as the nerve impulses are not properly produced by the retina.
Why is screening for ROP necessary?
As the survival of premature infants is improving all the time, ROP has become more common. ROP occurs only in premature infants born more than eight weeks premature, or when birth weight is less than 1501 grams. In a majority of premature babies, the ROP is mild and settles on its own, without treatment, but in a few infants ROP progresses and requires treatment.
There are no symptoms of ROP and since it is not possible to predict which premature infant will require ROP treatment, it is necessary to screen all babies less than 32 weeks of gestation age, or less than 1501 grams. The screening is done by a specialist eye doctor (ophthalmologist). Usually the screening begins when the baby is four to six weeks old or is 33 weeks of gestation. It usually takes place fortnightly until the blood vessels in the baby’s retina are mature. Some babies will require only one examination, although some require at least two.
Stages of ROP
- Stages 1 and 2: The outer aspect of the retina is affected by the diminished blood supply, and the damage remains in the outer aspect of the retina. Majority of the babies born more than 10 weeks early will suffer some amount of ROP of these stages, but it resolves spontaneously without much effect on the vision.
- Stage 3: New blood vessels, developing on the ridge of the demarcation line separating the well-developed retina from the area where the vessels have not developed, can lose their normalcy. They begin to contract and may bleed.
- Stage 4: The contracting blood vessels and the scar tissue begin to pull the retina, leading to retinal detachment.
- Stage 5: The retina is totally detached from its normal position.
What happens during the ROP screening?
Drops are put into the baby’s eyes to enlarge the pupils, which enable the doctors to see the retina. Anesthetic drops may be instilled just before the examination. The doctor holds the baby’s eyelids with his fingers or with a small instrument, so that he can look at the baby’s retina with a special instrument. The doctor may also touch the surface of the baby’s eye to rotate it, to have a better view of the retina all around. The baby may not like the examination and may cry but it does not feel any pain during this examination. We have a lot of experience in preparing the babies for the eye examination, and make the examination as quick as possible, although we need enough time to have a proper examination.
What happens after screening?
This depends on the stage of ROP. The treatment may not be done by the same ophthalmologist who screened the baby. The baby may be transferred to another unit for treatment, as this is a specialist procedure. If the baby has stage 1 or 2 ROP, no treatment is necessary, but follow-up examinations are required. If it progresses to stage 3 ROP, then laser treatment will be given. The laser
treatment is not an operation as such, but it requires general anesthesia and it usually takes about one hour. The doctor will continue to check the baby’s eyes regularly to assess the effect of the treatment. After laser treatment the baby will require eye drops for a few days to help them heal. The treatment of stages 4 and 5 are complicated, but they are also very rare. The ophthalmologist will discuss with you in detail about this.
What will be the long term effect on the baby’s vision?
Studies have shown that about 50 to 80 per cent of stage 3 retinopathy babies have good vision following early treatment. Small number of babies with stage 3 ROP even after treatment may have significant visual loss. Most babies continue to see well, but all preterm babies as they grow are likely to develop short-sightedness, squint, lazy eye or glaucoma, so regular follow up with an eye doctor is necessary. If the baby has stage 1 or stage 2 ROP, regular eye outpatient clinic visits are not necessary. However, babies with stages 3, 4 and 5 will require regular follow up with an ophthalmologist, initially every two to three months, then every six months and finally on a yearly basis until the age of five to 72 years.