The Effect Of High And Low Molecular Weight Sodium Hyaluronic Acid Eye Drops After Crosslinking

Purpose: The objective of this investigation was to assess the impact of eye drops containing high molecular weight hyaluronic acid (HMW-HA) and low molecular weight hyaluronic acid (LMW-HA) on corneal nerve regeneration, dendritic cell (DC) density, corneal sensitivity (CS), and ocular surface parameters in patients with keratoconus following corneal crosslinking (CXL).

Methods: Sixty-three eyes of 55 keratoconus patients were randomized to instill eye drops containing HMW-HA (n: 20) for 12 months, LMW-HA (n:23) for 12 months and polyvinyl alcohol (n: 20) until the epithelial defect closure in the control group after CXL. Subbasal nerve plexsus (SNP) was imaged with corneal confocal microscopy (CCM) and ACCMetrics program was used to quantify corneal nerve fiber density (CNFD), corneal nerve fiber length (CNFL), corneal nerve fiber branching density (CNBD) and corneal nerve fiber total branching density (CTBD). DC density was calculated with Image J software. CS was measured using the Cochet-Bonnet esthesiometer. Ocular Surface Disease Index (OSDI) questionnaire, non-invasive break-up time (NI-TBUT) were evaluated. All measurements were performed before CXL and postoperatively after 1, 3, 6 and 12 months.

This study assessed individuals aged 18 and above diagnosed with keratoconus and scheduled for epithelium-off CXL. A total of 63 eyes from 55 keratoconus patients were randomly assigned using computer-generated randomization (www.random.org/integers) into three groups: 20 eyes in the HMW-HA group, 23 eyes in the LMW-HA group, and 20 eyes in the control group without the administration of artificial tears.

Post-CXL, the HMW-HA group received topical HMW-HA (Comfort Shield®, i.com medical GmbH, Munich, Germany) three times daily for 12 months, the LMW-HA group received topical LMW-HA (Thealose Duo®, Thea, Clermont-Ferrand, France) three times daily for 12 months, and the control group received topical polyvinyl alcohol (Refresh, Allergan, Dublin, Ireland) three times daily until epithelial defect closure. All participants underwent accelerated epithelium-off CXL (A-CXL) for 10 minutes with 9 mW/cm² ultraviolet-A irradiation. The postoperative standard treatment regimen included topical moxifloxacin (0.5% Vigamox, Alcon Inc, USA) for one week, topical dexamethasone (0.1% Dexasine-SE, Kaysersberg Pharmaceuticals, France) for one week after epithelial closure, followed by topical loteprednol 0.5% (Lotemax, Bausch \& Lomb, USA) for three weeks.

Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), and manifest spherical equivalent (SE) were recorded at all visits. The assessment was carried out in the following order: Ocular Surface Disease Index (OSDI) questionnaire, noninvasive tear break-up time (NIBUT), corneal tomography (Pentacam, OCULUS, Wetzlar, Germany), corneal sensitivity, corneal fluorescein staining, and CCM imaging. Examinations were conducted preoperatively and at the postoperative 1th, 3rd, 6th and 12th months.

Eligibility Criteria:
Inclusion Criteria:

* Keratoconus patiens aged 18 and above who had been scheduled for corneal crosslinking

Exclusion Criteria:

* Dry eye disease, corneal thickness below 400 micrometer, pregnancy, breastfeeding, topical or systemic drug use, eye disease other than keratoconus, systemic diseases, active atopy or allergy, contact lens use, ocular surgery history.