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Although contact lenses have long been established in ophthalmology, practical aspects of handling contact lenses is becoming increasingly less important in the clinical training as specialist for ophthalmology. Simultaneously, for many reasons injuries due to wearing contact lenses are increasing. In order to correct this discrepancy, information on contact lenses and practical experience with them must be substantially increased from a medical perspective. This review article deals with the most important aspects for prevention of complications, i.e. contact lens hygiene.

The author presents the standards for testing the biocidal effectiveness of combined cleaning disinfection solutions (RDK solutions). By means of literature searches it was investigated whether the updated table of the optometrist Gary Andrasko in the internet is usable with respect to compatibility of combinations of commercially available contact lenses and commonly used RDK solutions by assessment of surface dye affinity. The methods used by Andrasko and the scientific basis of his approach are questioned based on various criteria and the value of the table is negated. The instructions for care given by the manufacturers of contact lenses are recommended.

With increasing numbers of contact lens wearers, Acanthamoeba infections are also more frequent all over the world and also in Hungary. Despite improved diagnostic and therapeutic possibilities it can still cause serious visual loss. In this study the symptoms, signs, diagnostics and treatment options for Acanthamoeba keratitis (AK) in patients treated in our department are presented and compared to the literature.Between 2001 and 2006 a total of 11 patients were treated in our department for Acanthamoeba keratitis.The mean age of the patients was 30 years and the 8 female and 3 male patients were all contact lens wearers. In six cases the right eye was affected and in five cases the left eye. Poor and improper contact lens hygiene was the cause of infection in all cases and 82% of the infections occurred in the summer period between June and September. In addition to long-term conservative treatment, perforating keratoplasty was performed in six cases. After the therapy the best visual acuity was 0.6, but 4 of the patients had a serious visual loss. Follow-up time ranged from 6 months to 5 years.Early diagnosis and long-term suitable local therapy are necessary for effective recovery. If the patient wears contact lens and there is severe pain with ring infiltration in the cornea, Acanthamoeba infection should be considered and suitable therapy should be given. Immediately performed perforating keratoplasty does not lead to visual improvement. Prevention by informing the patients about adequate hygiene and use of the cleaning solutions is one of the most important tasks of contact lens specialists.

In Ungarn erhoht sich die Zahl der Kontaktlinsentrager stetig. Damit steigt auch die Wahrscheinlichkeit des Auftretens einer Akanthamobenkeratitis. Obwohl immer mehr diagnostische und therapeutische Moglichkeiten zur Verfugung stehen, wird der erreichte Visus durch diese Augeninfektion sehr stark gefahrdet. In den letzten Jahren behandelten wir in unserer Klinik immer mehr Patienten mit Akanthamobenkeratitis. In der vorliegenden Studie werden die Symptome der Krankheit sowie die von uns eingesetzten Behandlungen dargestellt und mit den Angaben in der Fachliteratur verglichen. Zwischen 2001 und 2006 haben wir in unserer Klinik 11 Patienten mit Akanthamobenkeratitis behandelt. Das Durchschnittsalter der Patienten betrug 30 Jahre (16–60 Jahre). Die 8 Frauen und 3 Manner waren alle Kontaktlinsentrager. Die Infektion trat in 6 Fallen am rechten Auge, in 5 Fallen am linken Auge auf. In jedem Fall war schlechte Kontaktlinsenhygenie eine der Ursachen. In 82% der Falle trat die Infektion in der Zeit zwischen Juni und September auf. Neben der konservativen Therapie zur Bekampfung der Akanthamobenkeratitis wurde in 6 Fallen auch eine perforierende Keratoplastik durchgefuhrt. Bei der letzten Kontrolluntersuchung war die beste korrigierte Sehscharfe im Durchschnitt 0,6, aber 4 der Patienten hatten ihre Sehkraft am betroffenen Auge fast vollstandig verloren. Der Verlauf bzw. die Behandlung dauert 6 Monate bis 5 Jahre. Der Fruhdiagnose kommt hinsichtlich Verlauf der Krankheit eine sehr grose Bedeutung zu. Bestimmte Angaben in der Anamnese (das Tragen von Kontaktlinsen, heftige, ausgepragte Schmerzen, Ringinfiltrat) lassen beim Auftreten einer Keratitis einen moglichen Akanthamobenbefall vermuten und die Patienten sind dementsprechend zu behandeln. Eine sofort ausgefuhrte perforierende Keratoplastik fuhrt zu keinem besseren funktionellen Ergebnis. Unsere wichtigsten Aufgaben sind die zielgerichtete Pravention durch effektive Aufklarung der Kontaktlinsentrager uber die Bedeutung und Methoden der richtigen Kontaktlinsenhygiene.

The use of preservatives such as benzalkonium chloride (BAC) usually increases the toxicity of pharmaceutical tear substitutes. HP-guar has been recently introduced as a new artificial tear substitute and includes the preservative Polyquad (0.001%), which is considered to be non-toxic. We therefore examined the effect of preserved (cetrimide 0.01%) and unpreserved HPMC (hydroxypropylmethyl cellulose) and HP-guar in dose and time-response experiments in a human corneal and conjunctival epithelial cell culture model.Immortalized human conjunctival and corneal epithelial cells were cultured in 96-well plates at 37 degrees C with 5% CO(2) and exposed to the test solutions. The ATP content was quantified by means of a luminescence-based ATP assay, intracellular esterase activity by double fluorescent viability staining (calcein AM/ethidium homodimer D-1) and cell migration by a colony dispersion assay. All experiments were performed in triplicate and repeated at least once. The significance of differences was determined with an unpaired two-sided t-test.HPMC with preservative severely reduced the ATP content at all concentrations tested. Unpreserved HPMC, however, showed an inhibition of ATP production only at 100% and good esterase activity. HP-guar with and without preservative were found to reduce ATP activity more than unpreserved HPMC, but the unpreserved solution was found to reduce cellular ATP levels significantly more than the preserved solution.The new preservative Polyquad induced significantly less cytotoxicity than cetrimide. However, even unpreserved HP-guar can induce cytotoxicity in vitro, while unpreserved HPMC remains a good alternative tear substitute with low cytotoxicity.

The microbiological examination of contact lens storage solutions may reveal the etiological organisms responsible for keratitis and additionally harbour environmental contaminants.From 1995 to 1998, conjunctival and corneal smears and scrapes, as well as the storage solutions of 55 soft contact lens wearers were examined microbiologically in a prospective non-randomised cohort study involving 53x unilateral and 2x bilateral cases of keraitis.In 42 of the in-use contact lens storage solutions, the following organisms were found: 8x Bacillus sp., 7x P. aeruginosa and 8x other pseudomonads, 6x Alcaligenes xylosans, 4x Serratia liquefaciens, 4x Enterobacter sp., 4x coagulase negative staphylococci, 3x Serratia marcescens, 3x S. aureus, 2x Streptococcus faecalis, 1x Klebsiella oxytoca and 5x Acanthameba. A significant correlation of ocular cultures was found for Pseudomonas, Enterobacter, Serratia, S. aureus, S. faecalis and Acanthameba, but not for Bacillus, Alcaligenes, and coagulase negative staphylococci. Fungi were not found. The more pronounced the clinical picture, the more Gram-negative bacteria were isolated.The microbiological examination of soft contact lens storage solutions of 55 keratitis patients confirmed that the microbes responsible were to be found in the fluid, in addition to environmental contaminants.

Contact lens wearers are subject to increased risk of infection, and an attempt was made to determine which factors cause the overproportional risk of infection?The aim of this paper is to explain with appropriate bibliographic support why people who wear contact lenses are at risk of infection.The relative risk of keratitis is a function of the lens material and the wearing time of the contact lenses. Extended wear of hydrogel lenses is associated with an overproportional risk of infection. According to the literature, the frequency of complications in contact lens wearers generally is the result of poor hygiene in 66% of the cases. The general lack of hygiene among contact lens wearers must, therefore, be regarded as one cause among pathophysiological mechanisms of the eye. The microbial spectrum favors gram-negative bacteria living in a wet environment such as Pseudomonas, Serratia and parasites like Acanthamoeba.The specific spectrum of pathogens and new problem organisms not only challenge the fitter but also the manufacturers to adapt hygiene (sanitary) measures and products to the new development. Disposable contact lens systems are the first step, but they do not solve all the problems of contact lens wearers. Therefore, the importance of contact lens hygiene must be especially emphasized when the ophthalmologist is giving instructions to the patient. On the other hand, hygiene should also not be neglected by the contact lens fitters since it is part of the whole problem.