The patient was treated for endophthalmitis.

What pre-operative, peri-operative and post-operative measures could have reduced the risk?

Answer
Post-operative endophthalmitis is usually caused by bacteria indigenous 
to the patient's skin, eyelid and conjunctiva. 
Pre-operatively the patient's condition be optimized where possible.
This mean any patients with ipsilateral or contralateral conjunctivitis
should not undergo surgery. Presence of blepharitis should be treated 
with lid hygiene and possibly with topical antibiotic cream such as 
chloramphenicol. Presence of mucocele is a contra-indication and 
dacryocystorhinostomy should be performed first. However, patients 
with nasolacrimal duct blockage and are unsuitable for DCR may 
undergo surgery provided there is no discharge and the patient has
received a short course of  pre-operative topical antibiotic such as 
chloramphenicol.

Peri-operatively, the eyelid and the conjunctival sac should be cleaned 

with anti-septic. The best solution is aqueous povidone iodine 5%. 
For maximum effect, the iodine should be left on the site for at least 
one minute.

Trimming of the eyelashes was once popular but now discarded as 

it does not affect the incidence of endophthalmitis. In addition, the use 
of adhesive drape effectively keep the eyelashes out of the operative field. 

Some surgeons advocate the use of antibiotic such as vancomycin in

the irrigating solution. The benefit of this is controversial.

Perioperatively, subconjunctival injection of gentamicin or cefuroxime

are routinely used to reduce the risk of endophthalmitis.

 

Tell me how you perform a vitreous tap and intravitreal antibiotic?

Answer
This should be carried out in the operating room under sterile condition.
The microbiologist should be informed so that the specimen will be 
examined and cultured appropriately.
A combination of antibiotics are prepared prior to the procedure and 
I would use two syringes each containing 0.1 ml of antibiotics. The
combination I use are amikacin 0.4mg in 0.1 ml and vancomycin 1mg
in 0.1 ml.
The procedure is carried out under either topical or peribulbar anaesthesia 
and the eye is cleaned with iodine.
A 23 G needle on a Mantoux syringe is ideal for the task. The needle is 
entered from the temporal side about 4 mm behind the limbus. The needle 
should be pointing towards the centre of the vitreous. 0.2 ml of vitreous 
is withdrawn and some of the content is placed on the culture medium. 
The remaining content will be sealed and sent for microscopy. The 
prepared antibiotics are injected through the same site into the vitreous.

 

Why do you use the antibiotics mentioned in your last answer?

Answer
It is important to cover both Gram negative and Gram positive bacteria. 
Amikacin covers most Gram negative bacteria whereas vancomycin covers the Gram positive bacteria.
 

Is 3-port vitrectomy preferable to needle aspiration for obtaining vitreous sample?

Answer
Theoretically, 3-port vitrectomy will give a larger sample and cause 
less retinal traction. However, the Endophthalmitis Vitrectomy Study 
shows no differences in the complication rate and culture yield between the two techniques.
 

What are the most common bacteria isolated from post-operative endophthalmitis?

Answer
Staphylococcus epidermidis, Staphylococcus aureus and Streptococcal species.

 
 

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