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

Marmara University63 enrolled

Overview

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.

Interventions

in vivo Corneal Confocal MicroscopyDEVICE

CCM was performed using the Heidelberg Retinal Tomograph 3 with the Rostock Cornea Module (HRT3-RCM, Heidelberg Engineering GmbH, Germany) under topical anesthesia. A viscous gel (Viscotears, Novartis Pharmaceuticals UK) served as a coupling agent between the cornea and the applanation cap. The subjects were instructed to focus on the fixation light with the unexamined eye to ensure proper positioning. Five high-quality images of the SNP were selected and analyzed using the automated tracing of nerve fibers program (ACCMetrics, M.A. Dabbah, Imaging Science and Biomedical Engineering, Manchester, England).

Corneal SensitivityDIAGNOSTIC_TEST

Corneal sensitivity was evaluated using a Cochet-Bonnet esthesiometer (Luneau Ophtalmologue, Chartres, France), comprising a nylon filament measuring 60 mm in length and 0.12 mm in diameter. Participants were instructed to maintain a forward gaze while the esthesiometer gently made perpendicular contact. The procedure involved gradually decreasing the filament length in 5 mm increments, starting from 60 mm, until the initial response from the subject was detected.

Non invasive tear break up timeDEVICE

Noninvasive tear break-up time (NI-TBUT) was assessed using a Sirius Scheimpflug camera (CSO, Florence, Italy) and the device automatically provided the average NI-TBUT value

Ocular Surface Disease Index QestionnaireDIAGNOSTIC_TEST

The Ocular surface disease index (OSDI) questionnaire consists of a total of 12 questions categorized into three subscales as follows: ocular symptoms, vision-related function, and environmental triggers. Each patient is asked to rate the symptoms on a 5-point scale ranging from never (0 score) to always (4 score) for every question in the questionnaire. The fourth and fifth questions in the first section, concerning blurred vision and reduced vision symptoms, were excluded from the questionnaire as these symptoms may already be present in patients with keratoconus disease. The total OSDI score was calculated according to the formula: OSDI = \[(sum of scores for all questions answered) × 100\] / \[(total number of questions answered) × 4\].

Corneal tomographyDEVICE

Scheimpflug-tomography device (Pentacam, OCULUS, Wetzlar, Germany) was used for measurement of keratometric values.

Outcomes

Primary Outcomes

Corneal nerve fiber density (CNFD)

Automated tracing of nerve fibers program - CCMetrics (CCMetrics; M. A. Dabbah, ISBE, University of Manchester, Manchester, UK) was used to analyze CNFD.

Time frame: Baseline

Corneal nerve fiber density (CNFD)

Automated tracing of nerve fibers program - CCMetrics (CCMetrics; M. A. Dabbah, ISBE, University of Manchester, Manchester, UK) was used to analyze CNFD.