Retinopathy of Prematurity
What is Retinopathy of Prematurity (ROP)
Retinopathy of prematurity (ROP) is a potentially blinding disease caused by an abnormal development of the retinal blood vessels in premature infants. The retina is the inner layer of the eye that receives light and turns it into visual messages that are sent to the brain. When a baby is prematurely born, the retinal blood vessels can grow abnormally. Most ROP resolve without damaging the retina.
When a ROP is severe, it can cause the retina to pull away or detach from the wall of the eye and possibly cause blindness. Babies 1800 grams or less and are born before 34 weeks gestation are at highest risk.
How many infants are born with a ROP?
Approximately 2 out of 100 preterm babies screened for ROP, actually need treatment .
What determines the severity of ROP?
Birth weight and gestational age are the most important risk factors for the development of severe ROP. Other factors that are associated with the affliction from ROP include anemia, poor weight gain, blood transfusion, respiratory distress, breathing difficulties, and the overall health of the infant. Close monitoring has decreased the impact of oxygen use as a risk factor for development of ROP. However, lower levels of administering oxygen do not affect the degree of severity of ROP.
How is ROP diagnosed?
Ophthalmologists who are skilled at evaluating an infant’s eyes can also diagnose ROP. They examine the eyes after the pupils are dilated with thr help of drops. Current, active research is aimed at evaluating the effectiveness of digital photography for diagnosing ROP. Infants who weigh under 1800 grams (3.3 lbs) and with a gestational age below 34 weeks undergo eye examinations to monitor for ROP [See figure 1]. However some term babies with associated risk factors (excessive O2 therapy) also require due screening.
How do doctors describe ROP?
ROP is described by its location in the eye (the zone), by the severity of the disease (the stage) and by the appearance of the retinal vessels (Plus disease). The first stage of ROP is a demarcation line that separates normal from premature retina. Stage 2 is a ridge, with height and width. Stage 3 is denoted by the growth of fragile, new, abnormal blood vessels. As ROP progresses the blood vessels may engorge and become tortuous (Plus disease) [See figures 2 and 3].
Who requires treatment?
When ROP reaches a certain level of severity, called Type 1, the potential for retinal detachment (and possible permanent vision loss) becomes great enough to warrant consideration of laser treatment.
What does the treatment involve?
Once it is determined that treatment is necessary, there are typically two options. The first method is laser ablation applied to the immature portion of the retina (See figure 4). This thereapy has been in practice for many a year and is continues to be the most common method of treatment. The second method of treatment involves an injection of medication into the eye. Such an injection may be administered as an alternative to, or in addition to, laser treatment. This is a newer treatment and while results have been encouraging, further research is being carried out to help determine potential long term side effects and the probable rate of ROP recurrence.
The outcome of laser or medical treatment for ROP is usually favorable with the disappearance of abnormal blood vessels and resolution of Plus disease. Despite accurate diagnosis, and timely laser treatment, the ROP sometimes continues to worsen, and the retina pulls away from the back of the eye. Eyes with retinal detachment caused by ROP generally have a poor visual prognosis. Retinal detachment can be treated with vitrectomy and/or scleral buckling procedure. Despite optimal treatment, some eyes with ROP progress to permanent and severe vision loss.
Why are eye examinations recommended after discharge from the hospital?
It is VERY IMPORTANT to regularly have the infant’s eyes examined after discharge from the hospital because ROP may not be resolved before discharge. Also, in spite of successful treatment, prematurity may lead to other vision-related abnormalities. Prematurity is a risk factor for the development of amblyopia (lazy eye), eye misalignment (strabismus), the need for glasses (even at a young age), and cortical visual impairment. Therefore, every premature infant requires the long-term attention of an ophthalmologist.