14
The reported incidence for hypotony with glaucoma implants ranges from 2%
14
to
89%.
26
Initial reports with the Ahmed valve in children, reported this complication to be less
common, 11-14% as reported by Coleman and Engelbert
10-11
In the larger series reported by
Djodeyre et al, the hypotony rate was 25%,
21
similar to our finding of 23%. We observed
11/60 (18%) cases of choroidal effusion, 5 of which were associated with Sturge-Weber
syndrome and choroidal hemangioma; a known risk factor. In fact, 5/12 (42%) of eyes with
Sturge-Weber have developed this complication, similar to the incidence of 3/10 (33%)
reported by Hamush.
12
We believe that using a 23-gauge needle for tube insertion and
partially ligating the tube with an absorbable suture are helpful. Coleman and co-workers
also changed needle gauge for the same reason.
10
We also feel that the angle at which the
needle enters the anterior chamber was important. By directing the needle a bit downward, as
if aiming for the center of the pupil, rather than keeping it parallel to the iris plane as
suggested by the manufacturer, we feel that a better seal was achieved. Perhaps this
angulation bends the tube and creates a slight kink further reducing the flow rate.
Endophthalmitis is a relatively rare complication of glaucoma implants. Two of our
patients had tube exposure or conjunctivitis prior to developing endophthalmitis. We believe
that tube exposure is a major factor for the development of this complication. Tube exposure
was seen in 8/60 eyes (13%) in our study, higher than that of 0-2% reported for glaucoma
implants in adults,
27-28
but similar to the previously reported rate of 10-11%
in pediatric
patients
11,20
A significant linkage between uveitis and exposure was found. The reasons for
this association remain obscure. It may be that the highly active immune system in these
patients over produces cellular or humoral factors that eventually cause donor sclera melting.
It is interesting to note, however, that this high rate of exposure did not influence the success
rate in uveitic patients, which was similar to the other groups.
11,29
In contrast to our
experience, DaMata et al recently reported 19 uveitic glaucoma patients, 8 of whom were
