Assessing the Combined Diagnostic Value of Serum ACE Levels, Mantoux Test and Lymphopenia in Uveitis Patients from a Tertiary Eye Care Center in Southern India.

Purpose: To evaluate the diagnostic utility of serum angiotensin-converting enzyme (ACE) levels, along with Mantoux test and lymphocyte count, in patients with uveitis, with particular emphasis on differentiating ocular sarcoidosis and ocular tuberculosis. Methods: This prospective observational study was conducted at a tertiary eye care center in South India from December 2020 to June 2022. A total of 95 patients (118 eyes) with active uveitis were included. All patients underwent detailed clinical evaluation and standardized investigations including serum ACE levels, Mantoux test, and lymphocyte count. Diagnostic performance was assessed using sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Receiver operating characteristic (ROC) curves were used to evaluate discriminative ability. Results: The cohort had a mean age of 44.52±13.77 years with near-equal gender distribution (50.5% males). Anterior uveitis was most common (38.1%), followed by intermediate (18.6%) and posterior uveitis (16.9%). Defective vision (67.6%) and pain (44.1%) were predominant symptoms. Posterior uveitis was significantly higher in tuberculosis (53.3% vs 10.7%, p=0.002), while intermediate uveitis was more common in sarcoidosis (46.4% vs 6.7%, p=0.008). Elevated ACE (≥52 IU/L) was seen in 89.5% of sarcoidosis vs 33.3% tuberculosis (p=0.008; AUROC 0.819). Mantoux positivity was higher in tuberculosis (58.3%; AUROC 0.835). Lymphopenia showed 100% specificity but 10.5% sensitivity. Conclusion: Serum ACE is a useful adjunctive biomarker in the diagnosis of ocular sarcoidosis but lacks specificity when used in isolation. A combined approach incorporating serum ACE, Mantoux test, and lymphocyte count enhances diagnostic precision in uveitis, particularly in distinguishing sarcoidosis from tuberculosis in endemic regions.