Chronic Dry Eye After FS-LASIK Likely Has Immune System Etiology

Chronic dry eye disease (DED) development following femtosecond laser-assisted refractive surgery may be linked to immune and nervous mechanisms, according to a research article published in the Journal of Refractive Surgery. A team of investigators reached this conclusion following a study that reveals patients who develop DED after undergoing femtosecond laser-assisted in situ keratomileusis (FS-LASIK) reported milder symptoms, but had worse epithelial damage, and higher levels of tear inflammatory cytokines and neuropeptides than patients with DED who did not undergo FS-LASIK, the study authors report.

Researchers conducted the study to explore the clinical characteristics and tear film biomarkers of those who developed chronic dry eye following the refractive procedure and compare their findings with chronic DED patients who did not undergo laser surgery.

The researchers divided participants into 3 groups: those who developed chronic dry eye after FS-LASIK (n=36), those with DED who had not undergone FS-LASIK (n=39), and participants without DED or FS-LASIK used as a control group (n=34) groups. 

All participants underwent evaluations using the Ocular Surface Disease Index (OSDI), Numerical Rating Scale (NRS), Neuropathic Pain Symptom Inventory Modified for the Eye (NPSI-Eye), and Hamilton Anxiety Rating Scale (HAMA) questionnaires. Clinicians also examined the participants’ ocular surface parameters, tear cytokines, and neuropeptide concentrations.

Inflammatory cytokines evaluated using the LUMINEX immunoassay included granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-17A, IL-23, interferon-g (INF-g). Neuropeptides evaluated included alpha-melanocyte stimulating hormone (a-MSH), substance P (SP), b-endorphin, neurotensin (NT), oxytocin. 

The researchers report that the GM-CSF, INF-g, IL-17A, IL-23, a-MSH, NT, oxytocin, and SP concentrations in tears were all highest in the patients who developed chronic dry eye after FS-LASIK. The study also notes remarkable differences between the DED after FS-LASIK and DED without FS-LASIK groups. 

“This suggests that anti-inflammatory drugs may be more appropriate for patients with DED after FS-LASIK. On the other hand, a-MSH and oxytocin, as anti-inflammatory and neuroprotective markers, increased in the DED after FS-LASIK group; however, pro-inflammatory cytokines were also increased,” according to the researchers. “This suggests that ocular parameters are not regulated by the level of a single molecule but by the balance of a group of molecules.”

The study also notes depression and anxiety were more prevalent in patients with DED.

The study was limited by cross-sectional design and the lack of a DED severity classification system.