By Ramana S. Moorthy, MD
This prospective study found that the CD4/CD8 ratio of vitreous-infiltrating lymphocytes has a high diagnostic value in ocular sarcoidosis, comparable to that of the CD4/CD8 ratio in bronchoalveolar lavage fluid lymphocytosis for pulmonary sarcoidosis.
The authors determined CD4/CD8 ratios in vitreous samples from eyes with sarcoid and non-sarcoid uveitis, as well as peripheral blood CD4/CD8 ratios in each of these two groups.
The sensitivity and specificity of a vitreal CD4/CD8 ratio greater than 3.5 were 100 percent and 96.3 percent, respectively, for the diagnosis of ocular sarcoidosis. CD4/CD8 ratios of vitreous and peripheral T lymphocytes were significantly higher in eyes with sarcoidosis than in those without it. The CD4/CD8 ratios of vitreal T lymphocytes were significantly higher than those of peripheral T lymphocytes in eyes with sarcoidosis.
The authors concluded that diagnostic vitrectomy using flow cytometric analysis may be a useful adjunct for the diagnosis of ocular sarcoidosis, particularly in complex cases.
This data is intriguing and certainly represents an important method that can be applied to solidify the diagnosis of suspected sarcoid when histopathologic evidence is lacking. Since sarcoidosis is one of the most common causes of uveitis seen around the world and since histopathologic diagnosis is often lacking, the examination of inflamed vitreous in these patients with CD4/CD8 ratios greater than 3.5 can be highly suggestive of sarcoidosis, making this a very useful diagnostic tool.
I do have some reservations about this study, however:
1) The authors did not clearly anatomically classify the uveitis in each of these patients preoperatively. How many had anterior or posterior uveitis, intermediate uveitis, or panuveitis?
2) Since anterior uveitis accounts for nearly two-thirds of all sarcoid uveitis, did the authors exclude these cases?
3) The authors did not evaluate aqueous samples for CD4/CD8 ratios to determine if similar immunopathogenic changes were present.