Objectives: To investigate the correlation between the clinical grading of the severity of meibomian gland dysfunction (MGD) and meibomian gland area (MGA) loss detected using Sirius meibography in the upper and lower eyelids and to correlate these parameters with dry eye signs and symptoms. Methods: One hundred thirty eyes of 130 volunteer patients were enrolled. Meibomian gland dysfunction was defined as the presence of signs consistent with meibomian gland terminal duct obstruction and categorized between grades 1 and 4. Upper and lower MGA loss percentages were evaluated using Sirius meibography by two blinded examiners. Patients were categorized into two groups (positive and negative for MGD) based on their Ocular Surface Disease Index (OSDI) scores (>= 15 and <14, respectively) and MGD grades (>= 1 and 0, respectively). Results: The MGA loss percentage and ocular surface test results of the MGD group were greater than in the non-MGD group in both eyelids (P=0.001). Meibomian gland dysfunction grade and MGA loss for the lower eyelid was greater than that of the upper eyelids (P=0.002 andP<0.001, respectively). The OSDI score, tear film break-up time, and lissamine green staining were all significantly correlated with MGD grade and MGA loss in both eyelids (P<0.001). For the average measures of the MGA loss percentage in each scan, the intraclass correlation value was found as 0.994 (95% confidence interval [CI]: 0.992-0.995) for reader 1 and 0.988 (95% CI: 0.982-0.992) for reader 2. Conclusions: Our findings suggest that Sirius meibography, a noncontact imaging device, is a reliable tool for evaluating meibomian gland structure in patients with MGD and non-MGD of various ages and regardless of sex.