Abstract
Purpose :
To determine the effect on in vivo corneal immune response and clinical signs by the preservative benzalkonium chloride (BAK) in ocular hypotensive drugs for glaucoma before and after treatment, comparing BAK-preserved and BAK-free prostaglandin analogues.
Methods :
A randomized, longitudinal, controlled, double-masked clinical trial was conducted with 14 treatment-naive subjects (66.8±2.4 years) newly diagnosed with glaucoma, who received either BAK-preserved (latanoprost, LAT, n=7), or BAK-free ionic buffered system-preserved (travoprost, TRAV, n=7) prostaglandin analogue for 6 months. Central corneal DC densities of both eyes were quantified on IVCM at baseline, 1 month and 6 months post-treatment by a masked observer. Clinical improvement was assessed by intraocular pressure (IOP), corneal fluorescein staining (CFS) and tear break-up time (TBUT). Parametric and non-parametric tests were applied.
Results :
After 1 month of treatment, BAK-preserved LAT-treated eyes showed a 10% increase in DC density (baseline=126.0±33.2 cells/mm2, 1 month= 138.8±42.6 cells/mm2) in contrast to the BAK-free TRAV-treated eyes, which showed a 29% decrease in DC density (baseline= 90.63±22.6 cells/mm2, 1 month= 63.4±18.7 cells/mm2). This initial increase of corneal immune response in the BAK-preserved LAT-treated eyes resolved by 6 months (DC= 118.1±29.1 cells/mm2), while the BAK-free TRAV-treated eyes continued to maintain lower DC densities (DC=57.3±24.8 cells/mm2). Consistent with the initial increase and subsequent decrease of DCs in the LAT-treated eyes, TBUT initially decreased by 29% (LAT 1 month= 5.6±1.2s, TRAV 1 month= 9.25±1.6s, P=0.04) but stabilized by 6 months, comparable to that of TRAV-treated eyes (LAT 6 months= 6.3±0.7s, TRAV= 6.7±1.8s, P=0.6). IOP reduced significantly at 1 month with both LAT (P=0.03) and TRAV (P=0.007), to a comparable extent (P=0.40). CFS did not show any changes between both groups.
Conclusions :
IVCM demonstrated an increased ocular surface immune response to BAK in glaucoma therapy, which was observed as an early increase in DC density that began to subside by 6 months of therapy, not detected with clinical tests (CFS). This increase in DCs was accompanied by a decrease in TBUT. The ionic buffered system preservative did not activate the corneal immune response, and may offer a non-immunogenic alternative to eye drop preservatives for glaucoma therapy.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.