Vitreous Fluid Samples

The most common reason for removing the vitreous at autopsy is for biochemical and toxicologic analysis to assist in determining the cause and time of death.1112 Vitreous may also be removed in a limited autopsy procedure for cytologic examination to determine the presence of infection or malignancy (if cloudy vitreous was noted in life). However, removing and examining the whole intact eye will be much more informative under these circumstances, as the retina and other ocular tissues are often involved in the disease process.

It is important that only "normal" vitreous be sampled for biochemical analysis, as disease affecting the vitreous may well markedly alter its biochemical and cellular composition and lead to misleading results. I recommend that vitreous not be sampled for biochemistry from eyes with a history of retinal detachment, surgical manipulation, or posterior chamber disease affecting the vitreous. Nonvitreous fluids encountered in some eyes include blood, subretinal proteinaceous fluid, inflammatory exudates, and artificial vitreous (e.g., silicone oil) used in some vitreoretinal surgery. Note that the eye may be calcified or even ossified in some pathologic conditions, and vitreous sampling may be impossible. Vitreous sampling should be aborted in any eye that is small, wrinkled, and hard, or when there is firm (or gritty) resistance to puncture. A good practical test is to determine before puncture whether the eye is fluctuant, which is easily accomplished in the slightly flaccid postmortem eye by feeling transmitted pressure on the thumb and index finger of one hand placed medially and laterally on the sclera, when slight pressure is exerted on the superior sclera with the other index finger.

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