11. Source of organisms
• Bacteria from patient’s eyelids and
conjunctiva
• Confirmed by DNA fingerprinting (pulsed-
field elctrophoresis)
• Organisms introduced into the eye at the time
of surgery
• Small inocula usually eradicated by the
immune system.
22. Polymerase chain reaction
• Molecular technique with ability to
rapidly & exponentially replicate a
particular DNA fragment
• Single-stranded oligonucleotides
required to target templates (primer)
23. Method of specimen acquisition
• Aqueous specimen
• 27 – 30 G needle attached TB syringe
• 0.1 ml required
24. Method of specimen acquisition
• Vitreous undiluted specimen
• Vitreous needle tap
• Mechanized vitreous biopsy
25. Vitreous needle tap
• 22 G needle attached to syringe
• Pars plana location
• 0.1 – 0.3 ml required
• Dry tap convert to vitreous biopsy
26. Mechanized vitreous biopsy
• 20 G pars plana sclerostomy
• Vitreous cutter attached to syringe
• 0.1 – 0.3 ml
• Manual aspiration
27. Mechanized vitreous biopsy
• Visitrec Vitrectomy System
• 23 G guillotine cutter
• One-step sclerostomy, cutting, aspiration
• Suture closure not required
38. EVS: Source of organism
* Implications:
* 3. Keep area clean until wound is tight
* 4. Operate quickly
39. EVS
• EVS HM visual acuity
• Required 4-5 hand
presentations at 2 feet with
the light source from behind
the patient
40. EVS
• Main outcomes of EVS:
• IV antibiotics of no additional value
• Vitrectomy of benefit if presents with LP-
only vision
• Tap/biopsy of equal benefit if presents
with HM or better vision
41. EVS
• For patients with LP vision only
• Immediate vitrectomy is associated with:
• 3-fold increase in final VA>20/40 (33% vs 11%)
• 2-fold increase in final VA>20/100 (56% vs
30%)
• Half the rate of severe visual loss VA<5/200
(20% vs 47%)
46. EVS: Additional procedures
• Guidelines for early additional
procedures
• VA <5/200
• No red reflex or worse media
clarity
• Growth from initial culture
• At least one of these:
• 1mm increase in hypopyon
• Corneal infiltrate
• Increasing pain
47. Corticosteroids
• Intravitreal: controvesial
• Shah et al: Ophthalmology 2000 : No
value
• May dilute vancomycin concentration
• Inhibit inflammation in S. epidermidis
model
• Worse in S. aureus model
49. Treatment derived from EVS
• AC Tap
• Vitreous tap if VA better than LP
Vitrectomy if LP vision
• Intravitreal antibiotics
• Subconjunctival antibiotics &
steroids
