Describe post-traumatic endophthalmitis with its prevention and management.

Recognition and Immediate Management

• Endophthalmitis after trauma is infection of the intraocular cavities following a penetrating injury.
• It occurs in a substantial minority of open globe injuries and is the complication most likely to turn a repairable eye into a lost one.
• The risk factors are the ones that determine prophylaxis: a retained intraocular foreign body, which multiplies the risk several-fold; rural and soil or vegetable contamination; delay in primary repair beyond 24 hours; lens capsule rupture, which removes a barrier and provides a culture medium; a dirty or contaminated wound; and injury in a child
• The organisms differ from postoperative disease, and this governs the treatment: bacillus cereus is the feared one, associated with soil contamination and retained foreign bodies. It is fulminant, causing a corneal ring abscess, fever, marked systemic upset, proptosis and rapid destruction of the eye within hours. It is one of the few ocular infections that can blind an eye between one ward round and the next
• Also — coagulase-negative staphylococci, Staphylococcus aureus, streptococci, Gram-negative organisms; and fungi after injury with vegetable matter, which present indolently, weeks later
• Recognition is difficult because the eye is already inflamed from the injury, and this is the central clinical problem. The features suggesting infection rather than post-traumatic inflammation are: pain out of proportion and increasing after an initial improvement; worsening vision; a hypopyon; increasing vitritis with loss of the red reflex; corneal infiltrate or ring abscess; and fever and systemic upset, which is characteristic of Bacillus
• The rule IS: any deterioration after an initial improvement is endophthalmitis until proved otherwise
• Investigation — B-scan once the globe is closed, showing vitreous opacities and excluding a detachment or a retained foreign body; and aqueous and vitreous sampling for Gram and Giemsa stain, culture and PCR. The vitreous sample has a far higher yield than an aqueous tap
• Treatment — intravitreal antibiotics are the mainstay and are given at the time of sampling: vancomycin 1 mg in 0.1 mL with ceftazidime 2.25 mg in 0.1 mL, injected through the pars plana with separate syringes
• Unlike postoperative endophthalmitis, systemic antibiotics are given in post-traumatic disease, since the Endophthalmitis Vitrectomy Study excluded traumatic cases and the inoculum, organisms and tissue disruption differ
• Vitrectomy is undertaken more readily than after surgery, particularly with a retained foreign body, dense vitritis or a fulminant course; and it permits removal of the foreign body at the same sitting