Blebitis / Endophthalmitis - Microbiology
ale,
presenting 3 weeks after combined phaco/ trabeculectomy with MMC. He has a milky
appearance of a thin-walled bleb and 2+ cells in the anterior chamber. Slit
lamp examination shows cells in the anterior vitreous with clear fundus
details. The AC tap most likely shows which of the following organisms?
Streptococcus
Neisseria
Coagulase-negative
Staph
Enterococcus
Coagulase-positive Staph
Bleb-associated
endophthalmitis can occur at any time following successful filtration surgery.
The most common
causative organisms in early onset bleb infections (within 4 weeks of surgery)
are coagulase-negative Staphylococcus, while Streptococcus species are most
commonly the cause of late-onset infections.
Late onset
infections are more common, as the infection is typically related to
conjunctival button holes.
There is no evidence that blebitis
and endophthalmitis occur more frequently in combined cataract–glaucoma surgery
than in single glaucoma procedures.
Typically,
blebitis is caused by an external fistula of the filtering
bleb due to a long-term button hole of the
conjunctiva, particularly after MMC trabeculectomy. Even quiet buttonholes
should therefore be closed before blebitis or endophthalmitis occurs.
In some cases,
compression sutures may help to seal a button hole. However, it is more
effective and safer to interpose subconjunctival connective tissue (Tenon)
underneath the conjunctiva.
Buttonholes in
avascular thin filtering blebs cannot be closed by stitches from outside due to
the risk of additional holes created by the needle. The avascular tissue should
be excised and followed by an advancement of the conjunctiva or a free conjunctival
graft.
Fibrin or
cyanoacrylate glue applications are usually not effective, but amniotic
membrane transplantation is sometimes helpful.
Stages of blebitis:
1. 
Blebitis in which there is milky fluid within the bleb, but no cells within the
anterior chamber.
2. 
Aqueousitis characterized by blebitis plus
cells and flare in the anterior chamber. There is absence of cells in the
anterior vitreous of the phakic eye, and rare cells in the aphakic or
pseudophakic eye.
3. 
Vitritis has the findings of aqueousitis
plus cells in the anterior vitreous. It can be further subdivided depending
upon whether fundus details are or are not visible.
