Diagnostic vitrectomy

Is an important method for establishing the etiology of atypical intraocular inflammation and ruling out malignancy such as intraocular lymphoma.

In cases of endophthalmitis, it’s performed also for therapeutic purposes.

Has a high diagnostic yield for culture.

In case when anterior chamber tap is planned in addition to a vitreous biopsy, scleral cannulas should be placed prior to it (because insertion of cannulas in the soft eye is quite challenging).

Usually in diagnostic vitrectomy undiluted (collected with infusion off, around 1 ml) and diluted ( collected with infusion on, around 10 ml) vitreous samples are taken.

Important tips:

-Decrease a cut-rate less than 1000 to minimize morphological alterations

-Undiluted sample collected prior to diluted one, important to monitor the eye for choroidals

- As soon as choroidals are seen stop vitrectomy and open the infusion

- During diluted sample collection, important to remove the vitreous and not just aspirate a BSS solution