Ocular trauma and chemical injury — branching viva

Opening question

Examiner: Two children have just arrived. The first has an alkali powder burst to the eye; the second has a teardrop pupil and a soft eye after a dart. Take me through your first 60 seconds with each. [5]

Candidate: These are the two time-critical paediatric ocular emergencies, and the order of first aid decides the outcome. For the alkali splash, I irrigate immediately and copiously with saline or Ringer lactate, before any examination and before any pH check, because every minute of retained alkali destroys limbal stem cells. For the dart injury, the teardrop pupil and soft eye mean a suspected open globe, so I shield it with a rigid Fox shield and apply no pressure, keep the child nil by mouth with an antiemetic, and call ophthalmology for urgent surgery. Irrigate the chemical injury, shield the open globe — that is the frame. [5] [1]

Examiner: Why must you not examine the chemical-injury child before irrigating? [5]

Candidate: Because the history of a splash is enough to start irrigating, and the slit-lamp examination and the pH measurement each take minutes during which the alkali keeps liquefying tissue and killing stem cells. The delay to irrigation is the single biggest determinant of outcome, so irrigation is the assessment that comes first; the detailed examination follows once the eye is being flushed and the pH is on its way to neutral. [5]