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Retinitis Pigmentosa
Vision problems in Retinitis Pigmentosa
(RP)
RP is a progressive disorder which
affects the first the rods and then the cones of the retina,
which is the back layer of the eye. The effects are:
Night vision problems like being
afraid of the dark, stumbling when going across campus, bumping
into things in dark hallways, being unable to see the teacher
signing when she is standing next to (but not in the light
of) an overhead projector or film clip.
Blind spots: in the peripheral vision:
About midway between the pupil and the shoulder, blind spots
occur. At those spots information simply disappears. These
start out small and then enlarge, joining the others to form
a ring. The blind spots are not noticeable at first. When
they are big enough, the students will not notice things on
the floor, bump into objects, not realize someone is waving
or trying to get their attention, etc. The most important
problem, however, is that they begin to have problems following
a rapid conversation in a classroom particularly if everyone
is signing.
Tunnel vision: Once the blind spots
get big enough, they block out all peripheral vision and the
students can only see whatever they are looking at directly.
At this point (which can be as early as 10 years old in USH1),
they no longer like to play ball sports because they cannot
find the ball. Bumping into people and things becomes more
noticeable. Most importantly, they cannot follow a conversation
among 3 or more people without the assistance of an interpreter
(USH1) or microphones on each speaker (USH2).
Glare: Moving from a dim to light
environment is like walking out of a dark theater into bright
sunlight. Going from light to dim is like walking into a cave
with no light at all. The remarkable thing is that dim is
not black as most of us know it. It is like twilight or a
hall that does not have light for a stretch of only 10-15
ft. Unless coached to do differently, the students will stop
in a door or the middle of the hall and just wait until they
can see, which could be 5-10 minutes or even longer. They
need to learn to step to the side.
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