Abstract
Purpose :
Lubricant eye drops have effect on the corneal healing process and to evaluate corneal toxicity in high-frequency-application of these drops.
Methods :
The five eye drops are used in moderate to severe dry eye syndrome (DES). Main components of the compared drops are in A) emulsion of 0.18% HA, lipids and lipoic acid; B) cationic emulsion and cetalkonium chloride; C) 0.5% carboxymethylcellulose, polysorbate 80, erythritole, castor oil, Purite®; D) lipids, hydroxypropyl-guar, stearate, boric acid, EDTA, Polyquad®; E) 0.1% sodium hyaluronate (HA), carboxymethylcellulose, Purite®. As positive control Benzalkonium chloride (BAC) was used. All drops were applied on ex vivo rabbit corneas (n=5 per substance) (EVEIT system) hourly over 6 days. To observe healing 4 corneal abrasions (1.5 – 4.6 mm2) were applied mechanically. Erosion area was monitored daily by fluorescein stains images. Corneal vitality was measured by glucose and lactate concentrations in EVEIT outflow fluid. Corneal barrier function was quantified by photometric fluorescein permeation.
Results :
Epithelial healing was initially observed for all test substances A - E. At day 2 (substance B), at day 3 (substances C and D) and at day 5 (substance E) secondary epithelial degeneration occurred. For substance A we found early and complete healing of erosions at day 2. Histology revealed epithelial loss and severe alterations of the superficial stroma for test substances B, C, D and in three out of five corneas for substance E. Glucose and lactate concentrations stayed stable for substances A and D. Substance B and BAC showed higher lactate concentrations indicating metabolic stress. This was less pronounced for substances C and E. Fluorescein permeation was low only for substance A.
Conclusions :
The application of the test substance A with emulsion of 0.18% HA, lipids and lipoic acid resulted in rapid and stable corneal healing, metabolic health and intactness of the barrier function in the EVEIT. Substances B, C and D showed considerable corneal toxicity with secondary epithelial degeneration, metabolic stress and malfunction of corneal barrier function. We guess the preservatives like Polyquad®, Purite®, cetalkonium-chloride to exceed epithelial decontamination capacity of hydrogen peroxides and of membrane active substances.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.