Diagnostic vitreous biopsy in patients with uveitis: a useful investigation?

PURPOSE: To assess whether the results of microbial and cytological investigations of vitreous biopsy specimens are useful in the management of patients with intraocular inflammation. METHOD: A retrospective review of the medical records of 59 consecutive patients from consulting rooms, outpatient clinics and inpatient consultation who underwent intravitreal sampling between January 1997 and December 2003. Results of the biopsies were examined to determine if they altered management of the patient. RESULTS: The clinical diagnosis was correct in 37 of 59 patients (62.7%) with ocular inflammation. The organism was identified in 50% (7/14) of vitreous biopsies in patients with postoperative endophthalmitis. Of patients with endogenous bacterial endophthalmitis 16.7% (1/6) had the diagnosis confirmed by vitreous tap and 83.3% (5/6) had positive cultures from other sites that provided the diagnosis. Of the fungal endophthalmitis 80% (4/5) grew the fungus from the vitreous biopsy. Viral polymerase chain reaction identified the causative organism in 87.5% (7/8) of patients with clinical diagnosis of viral infection. 30.8% (4/13) vitreous biopsies in patients with clinically suspected masquerade syndromes were diagnosed as lymphoma. Vitreous biopsy results altered management significantly in seven (11.9%) patients. These patients included toxoplasmosis that was thought to be viral retinitis; malignant melanoma thought to be fungal endophthalmitis; chronic inflammation secondary to retinal detachment that was thought to be a neoplasm; three patients with infective endophthalmitis thought to be idiopathic uveitis and a patient with known lung carcinoma thought to have metastases who had lymphoma. In 67.8% (40/59) the vitreous sample helped to either confirm the diagnosis or exclude an infective cause. Complications from vitrectomy were hypotony (1/29) and retinal detachment (1/29). CONCLUSION: Clinical diagnosis based on examination findings and vitreous biopsy is highly accurate. Vitreous sampling altered the management of seven of 59 patients. Vitreous biopsy is a safe and useful method for diagnosing and excluding malignancy and infection in patients with ocular inflammation. Viral polymerase chain reaction is highly sensitive and accurate. The sensitivity of microbiological culture techniques for bacteria and fungi limits their usefulness.