Biocompatibility with the Ocular Surface and Antimicrobial Activity of a New Multi-Purpose Contact Lens Solution / Biocompatibilidad con la superficie ocular y actividad antimicrobiana de una nueva solución multipropósito para lentes de contacto / Biocompatibilidade com a superfície ocular e atividade antimicrobiana de uma nova solução de lentes de contato multipropósito

Abstract Introduction: Multipurpose solutions (MPS) for soft contact lenses (SCL) play an essential role in inhibiting potentially pathogenic agents. Their antimicrobial effectiveness is assessed in vitro and their safety in vivo, with clinical trials that include a combination of different solutions and lens materials. The objective is to assess the biocompatibility of a new SCL MPS produced in Colombia that contains polyhexamethylene biguanide (PHMB) and to determine its antimicrobial activity. Materials and Methods: This was a crossover study with 25 subjects who did not wear lens and who were fitted with different combinations of five SCL materials with either MPS or control physiological saline solution (CS). Corneal thickness, conjunctival hyperemia, corneal staining, and comfort were assessed after two hours of wearing SCL. Antimicrobial effectiveness was measured using ISO 14729 standard assays. Results: When considering SCL material, there was a statistically significant difference between the new MPS and the CS for Comfilcon A (p < 0.05). There was no statistical or clinically significant difference for corneal thickness or corneal staining between the combination of lens material and new MPS with the CS (p > 0.05). After two hours of lens insertion, comfort scores were higher than 7.8. The MPS reduced bacteria colony forming units (CFU) in over 3 log, and fungal CFU in over 1.0 log. Conclusions: The new MPS met the antimicrobial standards of ISO 14729, is considered safe and biocompatible with the ocular surface and retains high comfort levels.

Resumen Introducción: las soluciones multipropósito (SMP) para lentes de contacto blandos (LCB) desempeñan un papel esencial en la inhibición de agentes potencialmente patógenos. Su efectividad antimicrobiana se evalúa in vitro, y su seguridad, in vivo, con ensayos clínicos que incluyen una combinación de diferentes soluciones y materiales para lentes. El objetivo es evaluar la biocompatibilidad de una nueva SMP producida en Colombia que contiene polihexametileno biguanida (PHMB) y determinar su actividad antimicrobiana. Materiales y métodos: estudio cruzado con 25 sujetos no usuarios de lentes, que fueron adaptados con cinco combinaciones diferentes de materiales de LCB con una nueva SMP o solución salina fisiológica de control (CS). El grosor corneal, la hiperemia conjuntival, la tinción corneal y la comodidad se evaluaron después de dos horas de uso del LC. La efectividad antimicrobiana se midió utilizando ensayos estándar ISO 14729. Resultados: considerando el material del LCB, solo hubo una diferencia estadísticamente significativa entre la nueva SMP y el CS para el Comfilcon A (p < 0.05). Tampoco hubo diferencias estadísticamente o clínicamente significativas para el grosor corneal o la tinción corneal, entre la combinación del material del lente y la nueva SMP con el CS (p > 0.05). Después de dos horas de uso del lente, las puntuaciones de confort fueron superiores a 7.8. La SMP redujo las unidades formadoras de colonias (UFC) de bacterias en más de 3 log, y las UFC fúngicas en más de 1.0 log. Conclusiones: la nueva SMP cumplió con los estándares antimicrobianos de ISO 14729, y se considera segura y biocompatible con la superficie ocular, con altos niveles de confort.

Resumo Introdução: as soluções multipropósito (SMP) para lentes de contato macias (LCM) apresentam um papel essencial na inibição de agentes potencialmente patógenos. Sua eficácia como agente antimicrobiano se valia in vitro, e sua segurança, in vivo, como ensaios clínicos que incluem uma combinação de diferentes soluções e materiais para lentes. O objetivo é avaliar a biocompatibilidade de uma nova SMP produzida na Colômbia a base de polihexametileno biguanida (PHMB) e determinar seu potencial antimicrobiano. Materiais e métodos: estudo cruzado com 25 indivíduos não usuários de lentes, que foram adaptados com cinco combinações diferentes de LCM como uma nova SMP ou solução salina fisiológica como controle (CS). A espessura da córnea, a hiperemia conjuntival, a coloração da córnea e a comodidade, foram avaliadas após duas horas de uso da LCB. A eficácia antimicrobiana foi medida com ensaios padrão ISO 14729. Resultados: considerando o material da LCB, houve apenas uma diferença estatisticamente significativa entre a nova SMP e o CS, paro o Comfilcon A (p <0.05). Não houve diferença estatisticamente ou clinicamente significativa para a espessura da córnea ou a coloração da córnea, entre a combinação do material da lente e a nova SMP com o controle CS (p > 0.05). Após duas horas de uso, as pontuações de conforto foram superiores a 7,8. A SMP reduziu as unidades formadoras de colônias (UFC) de bactérias em mais de 3 log, e as UFC fúngicas em mais de 1.0 log. Conclusões: a nova SMP cumpriu com os padrões antimicrobianos ISO 14729, é considerada segura e biocompatível com a superfície ocular, com altos níveis de conforto.

Desinfecção com biguanida polimérica e as implicações na manutenção da segurança ambiental / Disinfection with polymeric biguanide and the implications for maintaining environmental safety

A manutenção do ambiente de saúde biologicamente seguro incorpora continuamente produtos e novas tecnologias pautados na isenção de riscos e em conhecimento técnico científico. Nesse sentido, a utilização de agentes químicos para o controle do crescimento microbiano configura-se como uma estratégia para reduzir o risco biológico associado às superfícies, uma vez que são apontadas como reservatórios de microrganismos e, portanto, podem influenciar na cadeia de contaminação cruzada. Este estudo tem por objetivo fornecer evidências para o uso do polihexametileno biguanida (PHMB) e, assim, contribuir para a efetividade dos procedimentos de limpeza e desinfecção das superfícies ambientais. Trata-se de um estudo desenvolvido em duas fases, uma caracterizada como revisão integrativa da literatura a outra como experimental in vitro, a fim de avaliar a atividade antimicrobiana do PHMB por meio das técnicas de Poço de Difusão em dupla camada de ágar, Diluição Inibitória Máxima (DIM) e contagem das Unidades Formadoras de Colônia (UFC). Com relação à revisão integrativa, observou-se escassez de evidências científicas, referentes ao uso do PHMB na desinfecção de superfície ambiental em serviços de saúde nas principais bases de dados. O PHMB, nas análises microbiológicas, demonstrou-se eficaz contra cepas padrão de Staphylococcus aureus e Pseudomonas aeruginosa, apresentando resultados semelhantes e/ou superiores aos do hipoclorito de sódio e detergente enzimático. Na desinfecção da superfície de aço inoxidável, contaminada intencionalmente por Pseudomonas aeruginosa, não houve diferenças entre os resultados do PHMB e da solução alcoólica a 70%(p/v), no entanto, para Staphylococcus aureus, observou-se que o PHMB foi mais eficaz na redução da carga microbiana quando comparado com a solução alcoólica a 70%(p/v). Concluindo, os resultados apresentados instigam-nos a desenvolver futuras pesquisas acerca do uso do PHMB em superfícies ambientais nos serviços de saúde, contribuindo, assim, com evidências científicas sobre o tema e promovendo o uso de forma segura

The maintenance of the biologically safe health environment continuously incorporate products and new technologies based on risk exemption and on techno-scientific knowledge. In this sense, the use of chemical agents for controlling microbial growth configure itself as a strategy to reduce the biological risk associated to surfaces, once they are pointed out as reservoirs of microorganisms and, then, can influence a chain of cross-contamination. This study aims to provide evidences for the use of polyhexamethylene biguanide (PHMB) and, therefore, to contribute to the effectivity of the cleaning and disinfection procedures of environmental surfaces. It is a study developed in two stages, one characterized as integrative literature review and the other as in vitro experimental, in order to evaluate the antimicrobial activity of PHMB through Diffusion-Well on double-layer agar techniques, Maximum Inhibitory Dilution (MID) and counting of Colony Forming Units (CFU). As to integrative review, the lack of scientific evidences was observed, regarding the use of PHMB in disinfection of environmental surface in health care on the main databases. PHMB, in microbiological analyses, proved to be effective against standard strains of Staphylococcus aureus and Pseudomonas aeruginosa, presenting similar and/or superior results to sodium hypochlorite and enzymatic detergent. In stainless-steel surface disinfection, intentionally contaminated by Pseudomonas aeruginosa, there were no differences between the results of PHMB and alcoholic solution at 70%w/v, however, for Staphylococcus aureus, it was observed that PHMB was more effective to reduce microbial load when compared with alcoholic solution at 70%w/v. To conclude, the presented results instigate us to develop future researches about the use of PHMB on environmental surfaces in health care, contributing, thus, with scientific evidences about the topic and promoting the use in a safe way

Benchmarking evaluation of five PHMB-based multi-purpose solutions and a silicone hydrogel contact lens / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To evaluate and compare the clinical performance of 5 kinds of polyhexamethylene biguanide(PHMB)based multi-purpose solutions(MPS)manufactured in China when used with a commercially available silicone hydrogel contact lens in terms of solution-induced corneal staining(SICS), ocular response(corneal staining and ocular hyperemia), corneal infiltrative events(CIE)and ocular comfort.<p>METHODS: This was a prospective, open label, randomized, parallel group clinical trial. Totally 162 participants who were at least 18y old were enrolled and randomized into 5 groups of PHMB-based MPS made in China: Complete^® MPS, Hydron^® Aqua-shining moist, Baoshining^TM, Weicon^® Fresh, Weicon^® 2000 MPS(abbreviated as C, H, B, W, and W2). All participants wore balafilcon A contact lenses with monthly disposal(Bausch & Lomb Purevision^®)in conjunction with the designated MPS on a daily wear for 3mo. Clinical visits were at baseline, 2wk, 1 and 3mo. SICS and CIE were reported as first event incidence per 100 Px-months. Ocular response was graded on 0-4 scale in 0.5 steps(0=none, 4=severe)and ocular comfort was assessed <i>via</i> a numeric rating scale(1-10 in 1-point steps, 1=poor, 10=excellent). Ocular comfort and ocular response variables were analysed using linear mixed model. CIE and SICS were analysed using Fisher's exact test and logistic regression. <p>RESULTS: There were 36(22%)Pxs who dropped out. SICS incidence for each MPS were: H(26.3%),B(20.8%), W(19.4%), W2(13.4%), C(12.8%). The SICS rate of H was significantly different to W2(<i>P</i> = 0.012)and C(<i>P</i> = 0.005). There were no significant differences in ocular response, CIE incidence and ocular comfort between different MPSs(<i>P</i>>0.05). Pxs with SICS had significantly lower comfort during the day and at the end of than those who did not have SICS. <p>CONCLUSION: Differences in SICS incidence were found between MPSs but not for CIE incidence, ocular response or ocular comfort. SICS in PHMB-based MPS was found to be associated with ocular discomfort.

Antimicrobial activity of different disinfectants against cariogenic microorganisms

Abstract The aim of this study was to assess the in vitro antimicrobial effects of chlorhexidine digluconate (CHX), polyhexamethylene biguanide (PHBM), and octenidine dihydrochloride (OCT) on cariogenic microorganisms by using their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). CHX, PHBM, and OCT were diluted in distilled water to the final test concentrations. Using the in-tube dilution method, Streptococcus mutans, Lactobacillus acidophilus, Lactobacillus rhamnosus, and Actinomyces viscosus were cultivated on blood agar and Mueller-Hinton broth (MHB) at 37°C for 48 h. They were read using a spectrophotometer to detect MIC. To determine MBC, samples in the range of the turbidity threshold after 24 h were transferred onto blood agar and evaluated for growth after 24 h. Different MICs and MBCs were observed in all disinfectants against each microorganism. The lowest MIC and MBC against S. mutans (60 mg/L) were obtained from PHBM. The lowest values against L. rhamnosus (15 mg/L, 30 mg/L), A. viscosus (30 mg/L), and L. acidophilus (15 mg/L, 30 mg/L) were determined by OCT. PHBM and OCT have the potential to be replaced with CHX because they were effective against cariogenic microorganisms.

Two Cases of Corneal Toxicity in Acanthamoeba Keratitis by Combined Topical Anti-Acanthamoeba Keratitis Eye Solution

PURPOSE: To present a case of corneal toxicity caused by therapeutic duplication during treatment of acanthamoeba keratitis as a complication of contact lens use. CASE SUMMARY: A 12-year-old girl with a history of wearing orthokeratology contact lenses and a 14-year-old girl with a history of wearing cosmetic contact lenses presented with ocular pain, injection, and decreased visual acuity. They were diagnosed as having acanthamoeba keratitis based on slit lamp examination, confocal microscopy and culture. After the patients were treated with polyhexamethylene biguanide (PHMB) and chlorhexidine, corneal epithelial defect and erosion occurred. Use of chlorhexidine was stopped, and PHMB was used to treat patients and recovery of the corneal epithelium with improvement in symptoms of acanthamoeba keratitis was found. CONCLUSIONS: Using PHMB and chlorhexidine together in treating acanthamoeba keratitis increases the risk of corneal toxicity. Therefore, these drugs should be avoided in combination.

Clinical Efficacy of Polyhexamethylene Biguanide Lid Scrub on Demodex Blepharitis

PURPOSE: To evaluate the treatment efficacy of polyhexamethylene biguanide (PHMB) lid scrub on Demodex blepharitis. METHODS: Thirty-one patients diagnosed with Demodex blepharitis were evaluated every 2 weeks during 8 weeks of lid scrub treatment with 0.4% PHMB. Patients underwent epilation of 4 eyelashes in each eye, and the number of Demodex lesions was counted. The patients answered questionnaires regarding ocular surface discomfort and underwent ophthalmologic exams including slit lamp and tear breakup time (TBUT). Compliance was recorded as 1 of 3 stages (good, moderate, poor). RESULTS: One patient was excluded for poor compliance. After PHMB lid scrub for 8 weeks, Demodex count was reduced in 28 of 30 patients (pre-PHMB 7.9 +/- 3.6 counts, post-PHMB 2.2 +/- 2.4 counts, p < 0.01). In addition, TBUT showed a statistically significant increase after PHMB lid scrub (pre-PHMB 2.7 +/- 0.8 seconds, post-PHMB 3.4 +/- 0.9 seconds, p < 0.01). Ocular surface disease index (OSDI) score was reduced in 28 of 30 patients (pre-PHMB 22.0 +/- 10.7 points, post-PHMB 7.4 +/- 6.0 points, p < 0.01). CONCLUSIONS: Eight weeks of treatment with polyhexamethylene biguanide lid scrub on Demodex blepharitis had good treatment efficacy for reducing Demodex counts and OSDI scores and increasing TBUT.

Caracterização do intumescimento de sistemas líquido-cristalinos de fase lamelar de monoleína e água contendo polihexametilenobiguanida / Characterization of swelling of lamellar phases of monoolein and water containing polyhexamethylenebiguanide

A monoleína é um lipídeo polar capaz de absorver água e formar sistemas líquido-cristalinos, os quais são utilizados como sistemas de liberação para administração de vários fármacos. Neste estudo foi avaliado o potencial de sistemas de fase lamelar constituídos por monoleína e água para veicular polihexametilenobiguanida (PHMB). A formação dos sistemas líquido-cristalinos foi caracterizada por microscopia de luz polarizada. Estudos de intumescimento foram realizados gravimetricamente em várias condições avaliando-se os efeitos de parâmetros como pH, força iônica e temperatura do meio de imersão. O processo de intumescimento foi caracterizado através da obtenção dos perfis de intumescimento e análise de sua cinética, além da determinação da capacidade máxima de intumescimento dos sistemas. Os sistemas de fase lamelar foram obtidos em presença de PHMB, os quais absorveram água rapidamente de acordo com cinética de segunda ordem e sofreram transição de fase, formando a fase cúbica. O intumescimento dos sistemas não foi influenciado pela presença do fármaco nos vários meios de imersão estudados, exceto pela imersão em meio ácido, no qual a presença do PHMB aumentou a captação de água. O intumescimento dos sistemas contendo PHMB não foi afetado pela força iônica do meio de imersão, porém foi diminuído com o aumento da temperatura. Desta maneira, sistemas líquido-cristalinos de monoleína e água foram obtidos e o processo de intumescimento foi caracterizado. Os sistemas apresentaram potencial para serem propostos como sistemas de liberação para administração de PHMB e estudos de liberação de fármacos serão realizados futuramente.

Monoolein is a polar lipid that absorbs water and forms liquid crystalline systems that are used as drug delivery systems for different medications. The aim of the present study was to investigate lamellar phases formed by monoolein and water as potential vehicles for the administration of polyhexamethylene biguanide (PHMB). Lamellar phase systems formed by monoolein and water containing PHMB were characterized by polarizing microscopy. Swelling studies were performed gravimetrically under different conditions for the evaluation of the effects of pH, ionic strength and temperature. Analyses of swelling profiles, swelling kinetics and maximum swelling capacity were performed. The lamellar phase systems of monoolein and water obtained in the presence of PHMB absorbed water very quickly following second-order swelling kinetics and formed a cubic phase. The swelling of the systems was not influenced by the presence of the drug in the immersion media studied, except under acidic conditions, in which the drug exhibited increased water uptake. The swelling of systems containing PHMB was not affected by the ionic strength of the immersion media, but was reduced with an increase in temperature. Liquid crystalline systems of monoolein and water were obtained and swelling behavior was investigated. The systems exhibited the potential for use as a drug delivery system for PHMB administration. However, further drug-release studies should be performed.

Sensitivity of Acanthamoeba Cyst to AntimicrobialAgents

Introduction: Acanthamoeba is an ubiquitous free-living protozoa which causes serious ocular problems. Acanthamoeba keratitis is becoming more prevalent amongst contact lens wearers. The disease can cause loss of vision and blindness if not treated properly. The objective of this research is to study the sensitivity of six Acanthamoeba spp. isolates, of which three were from the clinical isolates (HKL 95, HTH 40 and HS 6) and the remaining three from environmental isolates (TTT 9, TL 3 and SMAL 8) to antimicrobial agents. Methods: The antimicrobial agents chosen for this purpose were polyhexamethylene biguanide and chlorhexidine. Cyst suspensions from the chosen isolates were exposed to PHMB and chlorhexidine respectively. After 48 hours incubation time at 30°c,each mixture was filtered and filtration membrane was put onto non-nutrient agar laid with Escherichia coli. The agar plates were incubated for three days at 30°c and examined daily until day 14 to detect the presence of Acanthamoeba trophozoites under the inverted microscope. The presence of thropozoites indicated the ineffectiveness of the antimicrobial agents. Results: Both of the antimicrobial agents tested were found to be effective against Acanthamoeba cysts from all the test starins. Polyhexamethylene biguanide gave minimum cysticidal concentration (MCC) mean value of 2.848mg/mL while chlorhexidine showed MCC mean value at a concentration of 3.988mg/mL. Conclusion: It can be concluded that the Acanthamoeba were sensitive to polyhexamethylene biguanide and chlorhexidine.

Effect of Amoebicidal Agents on the Human Corneal Keratocytes in Vitro

PURPOSE: To evaluate the effect of polyhexamethylene biguanide (PHMB) and chlorhexidine on Acanthamoeba cysts and cultured human keratocytes. METHODS: Each well of two-fold diluted PHMB and chlorhexidine were treated on the Acanthamoeba cyst suspension of 5 x 10(4) cysts/ml for 8, 24, and 48 hours to measure the minimal cysticidal concentration (MCC) of each disinfectant and was exposed to the human corneal keratocytes of 5 x 10(4) cells/ml for same hours to measure the survival rate of keratocytes. Inverted phase-contrast micrograph and electron microscopy for observing the morphologic changes were evaluated. RESULTS: MCC of PHMB was 9.42 microgram/ml, 5.62 microgram/ml, and 2.37 microgram/ml, and chlorhexidine was 24.32 microgram/ml, 10.02 microgram/ml, and 7.02 microgram/ml respecitvely in 8, 24, and 48 hours. The survival rate of keratocytes at MCC was 91.7%, 64.6%, and 49.7% in PHMB of which significant decreases were found at 24 and 48 hours, and 95.7%, 90.6%, and 78.1% in chlorhexidine of which significant decrease was only found at 48 hours. The higher the concentration of disinfectants, cysts and keratocytes demonstrated more damaged appearance. CONCLUSIONS: The amoebicidal efficacy of PHMB and chlorhexidine was similar. However, in consideration of toxic effect on keratocytes by disinfectants, chlorhexidine is suggested to be more clinically useful than PHMB.

Acanthamoeba Keratitis Related to Orthokeratology Contact Lens

PURPOSE: To report 4 cases of Acanthamoeba keratitis related to orthokeratology lens overnight wear. METHODS: Four patients had histories of overnight orthkeratology lens wear of 10 months to 3 years when they presented with corneal ulcers. RESULTS: The organism isolated by corneal scraping was Aanthamoeba. The patients were treated with polyhexamethylene biguanide (PHMB), and chlorhexidine, resulting in a resolution of ocular inflammation. CONCLUSION: The risk of Acanthamoeba keratitis as a potential complication of overnight orthkeratology should be considered.

Molecular characterization of Acanthamoeba isolated from amebic keratitis related to orthokeratology lens overnight wear

In an effort to characterize, on the molecular scale, the Acanthamoeba initially isolated from the cornea of an amoebic keratitis patient associated with overnight-wear orthokeratology lens in Korea, we conducted mitochondrial DNA restriction fragment length polymorphism, 18S rDNA sequencing, and drug sensitivity analyses on the isolate (KA/PE1). The patient was treated with polyhexamethylene biguanide, chlorhexidine and oral itraconazole, which resulted in resolution of the patient's ocular inflammation. The majority of the molecular characteristics of the KA/PE1 were determined to be identical, or quite similar, to those of A. castellanii Ma strain, which had been isolated also from amoebic keratitis. The risk of Acanthamoeba keratitis as a potential complication of overnight orthokeratology is briefly discussed.

In Vitro Amoebicidal Efficacy of Hexamidine, Polyexamethylene Biguanide and Chlorhexidine on Acanthamoeba Ccular Isolates

To evaluate amoebicidal efficacy of various disinfectants, we treated ten ocular isolates of Acanthamoeba with polyhexamethylene biguanide(PHMB), chlorhexidine and hexamidine. Acanthamoeba cysts were collected from axenic nonnutrient agar plates from 4 week culture. Cyst suspension(100microliter) was inoculated on 96-well microplate with concentration of 105 cys/ml. Each well was treated with two-fold diluted hexamidine, PHMB and chlorhexidine(100microliter each, 8 and 48hrs). Each well was examined under the inverted microscope until 7 days after treatment. Minimal cysticidal concentration(MCC) of each disinfectant qas measured after five experiments. MCC of hexamidine, chlorhexidine and PHMB against ten ocular isolates ranged 6.07-500microgram/ml, 3.12-12.50microgram/ml, 1.17-4.68microgram/ml respectively in 48hr treatment. In 8hr treatment, MCC of PHMB and chlorhexidine ranged 4.42-12.50microgram/ml and 4.67-17.71microgram/ml, but hexamidine did not demonstrate cysticidal effect. For proper disinfection of contact lens, disinfectants having cysticidal efficacy should be included in the composition of contact lens solution. Among the currently used topical amoebicidal agents, PHMB showed the greatest cysticidal activity on ten ocular strains of Acanthamoeba in invitro study.

In Vitro Amoebicidal Efficiencies of Various Disinfectants Against Four Ocular Isolates of Acanthamoeba Keratitis

To evaluate amoebicidal efficacy of various disinfectants, we treated four ocular isolates of Acanthamoeba with three kinds of commercial available contact lens(CL) disinfectants, chlorhexidine, thimerosal, polyhexamethylene biguanide(PHMB) and hexamidine, Acanthamoeba cysts were collected from axenic nonnutrient agar plates from 4-week cultures. Cyst suspension(100microliter) was inoculated on 96-well microplate with concentration of 5x103 cyssts/ml. Each well was treated with three kinds of CL disinfectants(100microliter each, 4, 8, 12, 24hrs) and two-fold diluted chlorhexidine, PHMB and hexamidine(100microliter each, 8 and 48hrs). Only one CL disinfectant containing chlorhexidine(0.005%) and thimerosal(0.001%) showed cysticidal effect. Minimal cysticidal concentration(MCC) of PHMB, chlorhexidine, hexamidine ranged 1.17-3.12microgram/ml, 3.12-12.50microgram/ml, 8.64-52.07microgram/ml respectively with 48hr treatment. In 8hr treatment, MCC of PHMB and chlorhexidine were 4.42-12.50microgram/ml and 9.31-25.0microgram/ml respectively, but hexamidine did not demonstrate cysticidal effect. Therefore for proper sterilzation of contact lens and CL caes, effective disinfectant should be included in the composition of CL cleaning solution. Among the currently used topical amoebicidal agents, PHMB was the most potent cysticidal agent in in vitro study with four ocular stains of Acanthamoeba.