RESULTS
18 cases were included in the study. The mean age of the patients was 65 (range 14-82),
13 patients were women (72%) and 13 eyes were phakic (72%). The duration of
decreased vision ranged from 1 month to 2 years. Follow-up varied from 2 months to 2
year.
The median preoperative visual acuity was 20/200 with a range of 20/50 to counting
fingers at one feet. The median postoperative visual acuity was 20/70 ranging from
20/25 to counting fingers at 5 feet. All but one macular hole was closed after surgery
(94%). At the last recorded follow-up, 10 patients (56%) had improved their visual
acuity of at least 2 chart lines. For all cases, no adverse reaction related to trypan blue
was observed up to 1 year after surgery.
DISCUSSION
Several groups have reported the use of indocyanine green in macular hole surgery to
improve visualisation and to facilitate complete dissection of the ILM. But recently,
concerns have been raised in regards to its safety and to its potential toxicity to the retinal
pigment epithelium
(1,2)
.
Trypan blue (TB) is a well-known vital stain. Several animal studies have indicated its
teratogenic and carcinogenic potential
(3)
. In these studies, TB was administered via
intraperitoneal injection in dosages varying between 100mg/kg and 300 mg/kg. In
comparison, in cataract surgery, TB is injected locally at a dose of about 0,005 mg/kg.
Per operative use of TB at a concentration of 0.1% in anterior chamber surgery for the
vital staining of corneal endothelium did not produce ocular complication after an 8 year
follow-up
(4)
. Trypan blue is also used to facilitate capsulorrhexis during
phacoemulsification procedures in the absence of a red fundus reflex. To our knowledge,
no adverse effects have been reported.
Retinal tissue changes after long-term exposure to trypan blue were also evaluated in an
in vivo rabbit model
(5)
. In that study, no signs of toxicity were detected with light and
electron microscopy after continuous exposure of 0,06% TB to the retina for 1 month.
Recently, TB was succesfully used to stain epiretinal membranes during surgery for
proliferative vitreoretinopathy
(6)
.
No signs of toxicity related to TB have been reported in the litterature at a concentration
of 0,1%. All surgeries performed in this study used a lower concentration of 0,06%. In
fact, the concentration is actually quite lower since TB was constantly being diluted by
the continuous infusion.
