Can artificial tears prevent Acanthamoeba keratitis? An in vitro approach

Abstract

BackgroundThe use of contact lenses has increased in recent years as has the incidence of Dry Eye Syndrome, partly due to their use. Artificial tears are the most common treatment option. Since these changes can facilitate Acanthamoeba infection, the present study has been designed to evaluate the effect of three artificial tears treatments in the viability of Acanthamoeba genotype T4 trophozoites. Optava Fusion™, Oculotect®, and Artelac® Splash were selected due to their formulation.MethodsViability was assessed using two staining methods, Trypan Blue stain and CTC stain at different time intervals (2, 4, 6, 8 and 24 h). Trypan Blue viability was obtained by manual count with light microscopy while the CTC stain was determined using flow cytometry.ResultsTrypan Blue staining results demonstrated a decrease in viability for Optava Fusion™ and Artelac® Splash during the first 4 h of incubation. After, this effect seems to lose strength. In the case of Oculotect®, complete cell death was observed after 2 h. Using flow cytometry analysis, Optava Fusion™ and Oculotect® exhibited the same effect observed with Trypan Blue staining. However, Artelac® Splash revealed decreasing cell respiratory activity after four hours, with no damage to the cell membrane.ConclusionsThe present study uses, for the first time, CTC stain analyzed by flow cytometry to establish Acanthamoeba viability demonstrating its usefulness and complementarity with the traditional stain, Trypan Blue. Artelac® Splash, with no preservatives, and Optava Fusion TM, with Purite®, have not shown any useful amoebicidal activity. On the contrary, promising results presented by Ocultect®, with BAK, open up a new possibility for Acanthamoeba keratitis prophylaxis and treatment although in vivo studies should be carried out.

Acanthamoeba keratitis: a review of biology, pathophysiology and epidemiology

“…2 Acanthamoeba can be found in many water sources and supplies, such as tap and bottled water, distilled water bottles, jacuzzi tubs, spas, seawater, pond water, beaches, ocean sediments, fresh and saltwater lakes, swimming pools, 2,16 rivers, springs, irrigation water for crops, aquariums, dental treatment units, 10 shower heads and sewage. 2,20 It has also been isolated from water-air interfaces, air, soil, mud, 21 vegetation, and animals including mammals, amphibians, fish and reptiles. 15 In some hospitals, Acanthamoeba strains have been identified in surgical instruments, sterile intravenous saline, 22 dialysis machines, 2,10 ventilation systems, filters 23 and air-conditioning units, eyewash stations, contact lenses (CLs), CL cases 2,8,16,20,[24][25][26] and solutions.…”

“…2,20 It has also been isolated from water-air interfaces, air, soil, mud, 21 vegetation, and animals including mammals, amphibians, fish and reptiles. 15 In some hospitals, Acanthamoeba strains have been identified in surgical instruments, sterile intravenous saline, 22 dialysis machines, 2,10 ventilation systems, filters 23 and air-conditioning units, eyewash stations, contact lenses (CLs), CL cases 2,8,16,20,[24][25][26] and solutions. 2,8,16,20,25,26 This amoeba has been recovered from human tissues such as corneal biopsies, human nasal cavities, skin lesions, brain necropsies and cerebrospinal fluid, lung tissues, the throat, human faeces, 2 the kidneys 16 and intestines of healthy people.…”

“…4,22,[64][65][66][67][68][69] It is painful and difficult to diagnose and treat 1,5 and can lead to blindness or even enucleation. 16,20,28,32,34,38,56,[70][71][72][73] The devastating risk of vision loss is connected to scarring and corneal ulceration, 74 causing massive ocular injury. 50 Sight-threatening AK is most commonly found in young soft CL wearers and agricultural workers, even though it can also be present in non-CL wearers.…”

“…136 The majority of patients with AK are immunocompetent CL wearers. 16,20,87 Contaminated water: contact may occur in daily activities such as showering, using hot tubs, lakes, 31 tap water, 115,137 water storage tanks, swimming, 11,19,55 fishing, snow and water sports. 1,22,99,106 The exposure of CLs to water during the process of disinfection, such as while rinsing 11 and cleaning lenses with tap water before putting them in the storage case, 1 is very harmful.…”

“…18 CLs also affect ocular dryness by destabilising the lipid layer, which leads to poorer spread of the tear film and a reduction in the lipid layer in the prelens tear film resulting in increased evaporation. 20 This disturbance leads to an increased risk of infection, bacterial adhesion and desiccation of the ocular surface. 20…”