A 38-year-old type 1 diabetic presents with 23-gauge pars plana vitrectomy planned for non-clearing vitreous haemorrhage. The MOST appropriate pars plana incision site from the limbus in a phakic adult is:
- A 3.5 mm ✓
- B 2.0 mm
- C 3.0 mm
- D 4.0 mm
Correct answer: A. 3.5 mm
Explanation
In a phakic adult eye, the pars plana incision for vitrectomy is placed 3.5 mm posterior to the limbus to avoid the crystalline lens anteriorly and the peripheral retina posteriorly. In pseudophakic or aphakic patients, the incision can be moved 3.0 mm from the limbus. In children, 2.5–3.0 mm is used. Incisions too far forward risk lens damage; too far back risk peripheral retinal incarceration.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.