EXAMINATIONS FOR RETINOPATHY OF
PREMATURITY
ROP is a visually devastating disease that
often can be treated successfully if it is diagnosed in time. Because of
this, most newborn intensive care units (NICU) have regular screening
programs for ROP.
The examinations are done with an indirect
ophthalmoscope, a device that allows the ophthalmologist to get a
stereoscopic wide-angle view of the retina. A lid speculum is used to
hold the eyelids open, and a probe may be used to position the eye
during the exam. A drop of topical anesthetic is applied to each eye
prior to the exam to reduce the discomfort as much as possible.
Nevertheless, it is a stressful procedure for premature infants, and a
neonatal nurse is usually standing by to assist in the exam and to watch
for signs of excessive stress or other medical problems. Sometimes the
examinations need to be postponed if the infant's medical condition is
not stable enough.
It would be virtually impossible to examine all
infants who might develop ROP, since ROP in full-term infants has been
reported. Because of the expense and stressful nature of the
examination, screening programs should be concentrated on the population
with the highest risk of ROP. Unfortunately, there are no universally
accepted screening criteria, and each NICU must decide upon its own
standards. It is known that birthweight and gestational age are both
inversely correlated with the risk for ROP, so most screening programs
use one or both of these as the primary criteria. In our NICUs, all
infants with a birthweight of 2000 grams or less are examined. Many
units have lower cutoff levels (1750 grams, 1500 grams, or 1250 grams).
Infants over 2000 grams in our NICUs are examined if the neonatologists
feel that there is an increased risk in that individual. Several risk
factors for ROP have been identified that may motivate examinations
in infants that would not otherwise meet the screening criteria.
The timing of the initial examination is also
open to debate. Many units schedule the initial examination for six
weeks after birth, feeling that most infants are medically stable enough
by then to withstand the examination without ill effects. However, there
is good evidence that the time of onset of ROP is more closely related
to gestational age than chronological age (see the paragraph on this
subject on our main ROP page). Because of
this, we do our initial examinations at 33 weeks gestational age or 6
weeks after birth, whichever comes first, assuming that the infant is
stable enough for the examination.
Subsequent examinations are usually done every
two weeks until the retinal vessels are mature to the edge of the
retina. In patients with actively progressing ROP, examinations may need
to be done every week (or even every few days in patients with rush
disease). Once the retinal vessels are mature to the ora serrata, the
risk of visual problems from ROP is extremely low, and further retinal
examinations are not usually indicated.
Infants who are premature have an increased
risk of amblyopia (lazy eye) and strabismus (crossed eyes), even if they
have never developed ROP. For this reason, and because of the potential long-term
complications of ROP, we routinely re-examine all infants meeting
the ROP screening criteria at 6 months and again at 3 years of age.
The Country Hills Eye Center Home Page
Dr. Scott C. Richards Main Page
For information regarding the
Country Hills Eye Center phyician
specializing in retinal and diabetic eye diseases
www.countryhillseyecenter.eyemd.org
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