What is Retinopathy of Prematurity?
Retinopathy of Prematurity
Detailed Explanation
Retinopathy of prematurity (ROP) has been divided into five stages. Stages 1 and 2 customarily get better on their
own. Some eyes, however, go on to Stage 3
retinopathy of prematurity. This happens
when new blood vessels start to grow from the retina toward the center of the eye, forming
a ridge between retina that has blood vessels in the back of the eye, and the retina that
does not have blood vessels in the front of the eye.
This difference in the blood vessels of the retina is because the premature baby
has not had the time while in the womb to allow the blood vessels within the retina to
grow all the way from the optic nerve in the back of the eye to the front of the eye.
Stage 3 ROP exists when these disturbing new blood vessels grow out
from the ridge in the retina toward the center of the eye.
If this blood vessel growth becomes severe and is accompanied by “plus”
disease, the child may reach the point where treatment of the peripheral
retina with laser (or rarely freezing) treatment is performed. “Plus” disease is defined as enlarged and twisting blood
vessels in the back part of the eye.
Stage 3 ROP
Stage 3 ROP exists when these disturbing new blood
vessels grow out from the ridge in the retina toward the center of the
eye. If this blood vessel
growth becomes severe and is accompanied by “plus” disease, the child
may reach the point where treatment of the peripheral retina with laser
(or rarely freezing) treatment is performed. “Plus” disease is defined as enlarged and twisting blood
vessels in the back part of the eye.
Plus Disease
Peripheral retinal treatment can reduce, but not
eliminate, the chance of the ROP progressing to the potentially blinding
stages 4 and 5.
When stage 4 or 5 ROP is reached, the retina is detached and
other therapies can be performed.
Stage
4 ROP
One such therapy is scleral buckling, which involves
encircling the eyeball with a silicone band to try and reduce the
pulling on the retina.
Other therapies include vitrectomy (removal of the gel-like substance
called the vitreous that fills the back of the eye). Sometimes the removal of the
lens as well is required during vitrectomy to try and eliminate as much
pulling as possible from the retinal surface.
Removal of the lens is performed if the retina is touching the back
surface of the lens, which would make it impossible
to enter the eye for vitreous surgery without damaging the retina.
When scleral buckling is considered the appropriate
procedure, the success rate is 70% retinal reattachment. Vitreous surgery for
stage 4B, where the retina responsible for central vision is detached,
or stage 5, where all the retina is detached, had a success rate of 76%
reattachment.
The child’s vision after these procedures were in the ranges of:
20/60 to 20/300 for 15% of eyes
20/60 to 20/800 for 30% of eyes
20/60 to 20/1900 for 48% of eyes (ambulatory vision)
light perception for 72% of eyes
Ambulatory vision is defined as being able to see
objects and move around a room without stumbling or bumping into
obstacles. Unfortunately,
28% of children even with appropriate management and vitreous surgery
end up with no light perception.
Recently, vitreous surgery is being performed earlier,
at stage 4A, where the retina responsible for central vision remains
attached, and shows promise of success rates of up to 90%. Visual results in this
population are not available currently, but are suspected to be perhaps
better than when surgery is performed at stage 4B or 5.
The development of vision is dependent on many factors,
much of which we probably don’t fully understand, but certainly issues
relative to the child’s glasses needs, central nervous system
development, and developing the “wiring” for vision based on competition
between the two eyes are all factors that enter into the child’s final
visual acuity. Fortunately,
children are able to adapt to lower levels of vision and use their
vision at levels much higher than what their measured visual acuity
might suggest.
Children with a visual acuity of 20/200, which would be
classified as legally blind, very often function at a level much better
than that when they are
observed performing their daily tasks.
Certainly there is
much progress to be made in the area of retinopathy of prematurity and other forms of
pediatric retinal detachment that hopefully will yield even better visual results. Some of these things will be aided by the
development of drugs that can control this new blood vessel growth, as well as
developments of microelectronics and other tissue manipulation techniques.
In December of 2003, the
results of the Early Treatment Retinopathy of Prematurity Study were released. They
showed that treating eyes that are vascularly active with plus disease and with changes of
ROP in zone 1 yielded fewer eyes going on to stages 4 and 5 (retinal detachment).
The treatment performed in this study was primarily laser peripheral ablation and
the eyes were treated within two days of diagnosis. This study does support earlier
intervention and will reduce, hopefully, the number of children who go on to
blindness from retinal detachment.
For more in-depth
information on retinopathy of prematurity you can access the Physician's Education section
of our website:
http://www.ropard.org/learning/
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