Increased serum cystatin C levels in patients with idiopathic epiretinal membrane

Increased serum cystatin C may play a role in the pathogenesis of idiopathic epiretinal membrane (IERM). Physicians should be aware of this relationship and should refer patients to the ophthalmology clinic for screening.

To evaluate the serum cystatin C level in patients with IERM, and its associations with visual acuity.

Sixty-eight patients with IERM and sixty-nine controls were enrolled in this cross-sectional study. Based on the results of optical coherence tomography, patients with IERM were divided into four stages (I, II, III and IV). Serum cystatin C was measured in all participants. Serum cystatin C levels were compared between the control group and IERM group and between the IERM group with different optical coherence tomography stages. Multiple linear regression was used to evaluate the relationship between serum cystatin C and IERM stages and best corrected visual acuity.

Serum cystatin C level was higher in the IERM group than in the control group (P < 0.001). There were statistically significant differences in serum cystatin C among different stages of IERM (P_{I vs II} = 0.011, P_{I vs IV} < 0.001 and P_{III vs IV} = 0.040, respectively). There were significant differences in best corrected visual acuity among different stages of IERM (P_{I vs III} = 0.018, P_{I vs IV} < 0.001, P_{II vs IV} < 0.001 and P_{III vs IV} < 0.001, respectively). Regression analysis showed a positive correlation between serum cystatin C and best corrected visual acuity (t = 2.238 P = 0.029). The cut-off value of receiver operation characteristic curve of serum cystatin C for IERM was 0.775.

This study revealed that serum cystatin C may be involved in the pathogenesis of IERM and can predict its occurrence. Elevated serum cystatin C appears to be associated with the severity of the disease and relatively poor vision acuity in IERM patients.