A 58-year-old diabetic undergoes vitrectomy with silicone oil tamponade for complex proliferative diabetic retinopathy. Six weeks later the retina has redetached inferiorly beneath the oil. Which tamponade property explains this pattern of failure?
- A Silicone oil gradually dissolves into aqueous and loses all surface tension by six weeks
- B Standard silicone oil is lighter than water and floats, providing poor support to the inferior fundus ✓
- C Silicone oil induces rapid fibrous contraction that pulls the inferior retina off the pigment epithelium
- D Silicone oil transmits intraocular pressure unevenly, creating a suction force at the inferior ora
Correct answer: B. Standard silicone oil is lighter than water and floats, providing poor support to the inferior fundus
Explanation
Conventional silicone oil has a specific gravity below that of water, so it rises and buttresses the superior retina while leaving the inferior fundus relatively unsupported. Persistent traction or an unclosed inferior break therefore produces redetachment under oil. This limitation is exactly why heavier-than-water agents such as Densiron 68 were developed for inferior pathology, which rules out option A since surface tension persists until removal.
Reference: Ryan's Retina, 6th ed.
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Written and medically reviewed by the StethoPrep medical team.