Tolerability and Efficacy of Topical Methotrexate in Ocular Surface Disease

Topical immunomodulators have gained popularity in the treatment of inflammatory dry eye disease (DED). In our tertiary DED population, ocular surface inflammatory signs and symptoms refractory to conventional treatments remain a diagnostic and therapeutic challenge. This two-part in vitro toxicity and in vivo clinical study aims to determine the safety and therapeutic potential of off-label use of topical methotrexate (MTX) for the treatment of recalcitrant ocular surface disease (OSD).

Aim 1 involved an in vitro toxicity assay where primary human corneal epithelial/stromal cells (HCEs and HCSCs, respectively) were established from de-identified donor corneal rims. Epithelial cells were separated and cultured in Dulbecco's modified Eagle's medium (DMEM), while stromal tissue was isolated, and the cells were sub-cultured in DMEM. HCEs and HCSCs were exposed to 1 mg/mL, 2 mg/mL, or 3 mg/mL of MTX. HCEs were also treated with 10 mg/mL of MTX. Cells were photographed at 24 and 96 hours post-treatment. Aim 2 involved MTX treatment for recalcitrant surface inflammation. A retrospective chart review was conducted on patients diagnosed with recalcitrant OSD who were treated with off-label topical 1 mg/mL MTX four times a day bilaterally. The ocular surface disease index (OSDI) and symptom assessment in dry eye (SANDE) were recorded to assess symptomatic changes. Changes in objective measurements were assessed by measuring Schirmer's test, corneal fluorescein staining (CFS), and palpebral conjunctival redness (PCR). Inferential statistical analysis was performed using paired t-test and Wilcoxon signed-rank test in STATA 16.

In vitro results for treated HCEs and HCSCs showed minimal changes relative to control across 1 mg/mL, 2 mg/mL, and 3 mg/mL MTX at 24 hours. Decreased cell survival of HCEs was noted after 96 hours of 1 mg/mL, 2 mg/mL, and 3 mg/mL MTX exposure. Cell survival of HCSCs at 96 hours in 1 mg/mL and 2 mg/mL MTX exposure was similar to control; however, at 3 mg/mL MTX exposure, decreased cell survival was noted. At 10 mg/mL MTX, loss of HCE cells was noted at 72 hours. Clinically, 19 patients were studied consecutively. Study times ranged from six to eight weeks, with a median follow-up time of two weeks between visits. Compared to before treatment, patients showed improvement in PCR (p=<0.01), OSDI (p=0.02), and CFS (p=0.03). SANDE and Schirmer's 1 were also improved but not statistically significant. Visual acuity, intraocular pressure (IOP), and visual analog scale (VAS) showed no statistical change across the treatment period.

Topical MTX demonstrated minimal cytotoxicity in vitro and appears to be well tolerated in our patient cohort. Topical MTX may play a role in the treatment of recalcitrant DED and OSD signs and symptoms, and further study with larger sample sizes is in progress.