Contact Lens

Evaluar el impacto de las lentes de contacto desechables en la calidad visual, comparando aberraciones ópticas, en ojos miopes, con y sin lentes de contacto. Método: Las aberraciones ópticas se midieron mediante el sistema del Trazado de Rayos Láser, el cuál es un método de medida objetivo, sobre un conjunto de 18 ojos, en 3 condiciones diferentes: a ojo desnudo, ojo más lentes de prueba, ojo con lentes de contacto desechables. Resultados: Existe una alta variabilidad entre sujetos, pero la tendencia general es que las lentes de prueba no modifican las aberraciones, mientras que las lentes de contacto tienden a incrementar las aberraciones oculares para pupilas grandes cerca de un 40% en promedio. Sin embargo tal incremento es mucho menor para pupilas más pequeñas. Conclusión: Este estudio revela que no se produce efectos significativos en la calidad de visión en pacientes que usan lentes de contacto desechables bajo condiciones de luz diurna, así como un pequeño descenso en visión nocturna. Palabras clave: Aberraciones, lentes de contacto blandas, método de trazado de Rayos.

Ophthalmology makes interesting reading and provides useful information. However, despite their claim that they have included articles from 1966 to 2006 the authors have missed what might be an important report on the use of alcohol delamination in the management of recurrent corneal erosions. 3 The paper was published in March 2006. The reason I bring this up is because it is likely that the paper would have had an impact on their conclusion and recommendation that phototherapeutic keratectomy (PTK) is the best modality of treatment of this condition. Alcohol delamination of the corneal epithelium (ALDCE) involves the application of a solution of 18-20% alcohol over the affected area and surroundings and delamination of the thus-loosened epithelium. The technique, on the basis of two reports with a follow-up of 2 years each, was found to be equally effective as PTK but offers advantages of simplicity and cost, besides being the only procedure where the pathological epithelial sheet can be removed intact and analyzed histologically. 3,4 In the first report, 3 ALCDE was shown to offer a success of around 90% over a 2-year follow-up of 12 treated patients, and in the second report 4 ALDCE demonstrated a total success rate of 83% (15 of 18 patients) and partial success in the remainder 17%. Two patients (of the initial 20) were lost to follow-up and no failures were seen over a 2-year follow-up period. Successful outcomes with this technique have also been reported by Agrawal et al 1 who applied it to a large area of the cornea although I have tended to restrict it essentially to the affected site. 2 The excimer laser is an expensive piece of equipment that is not readily accessible to all across the world. It is therefore important to draw attention to alternative modes of treatment that can offer acceptable outcomes.

Multipurpose solutions (MPS) often contain low concentrations of boric acid as a buffering agent. Limited published literature has suggested that boric acid and borate-buffered MPS may alter the corneal epithelium; an effect attributed to cytotoxicity induced by boric acid. However, this claim has not been substantiated. We investigated the effect of treating cells with relevant concentrations of boric acid using two cytotoxicity assays, and also assessed the impact of boric acid on corneal epithelial barrier function by measuring TEER and immunostaining for tight junction protein ZO-1 in human corneal epithelial cells. Boric acid was also assessed in an in vivo ocular model when administered for 28 days. Additionally, we evaluated Biotrue multi-purpose solution, a novel borate-buffered MPS, alone and with contact lenses for ocular compatibility in vitro and in vivo. Boric acid passed both cytotoxicity assays and did not alter ZO-1 distribution or corneal TEER. Furthermore, boric acid was well-tolerated on-eye following repeated administration in a rabbit model. Finally, Biotrue multi-purpose solution demonstrated good ocular biocompatibility both in vitro and in vivo. This MPS was not cytotoxic and was compatible with the eye when administered alone and when evaluated with contact lenses. We demonstrate that boric acid and a borate-buffered MPS is compatible with the ocular environment. Our findings provide evidence that ocular effects reported for some borate-buffered MPS may be incorrectly attributed to boric acid and are more likely a function of the unique combination of ingredients in the MPS formulation tested. Predose 0, 0, 0, 0 0, 0, 0, 0 0, 0, 0, 0 0, 0, 0, 0 Dosing day 8 0.2 (±0.6), 0, 0, 0 0, 0, 0, 0 0.3 (±0.6), 0, 0, 0 0.3 (±0.9), 0, 0, 0 Dosing day 15 0, 0, 0, 0 0, 0, 0, 0 0, 0, 0, 0 0, 0, 0, 0 Dosing day 22 0, 0, 0, 0 0, 0, 0, 0 0.2 (±0.4), 0, 0, 0 0.1 (±0.3), 0, 0, 0 Scores shown are for conjunctiva/anterior chamber/cornea/lens based on McDonald-Shadduck criteria. Average values shown (±standard deviation), n = 12 rabbits.

Glucose-selective holographic sensors were fabricated from unique tetrahedral 2-acrylamidophenylboronic acid (2-APB) incorporated with co-monomers poly(ethylene glycol) acrylate (PEG), (3-acrylamidopropyl)trimethylammonium chloride (ATMA) and [2-(acryloyloxy)ethyl]trimethylammonium chloride (AETA) into thin hydrogel films which were transformed into volume holograms using a diffusion method coupled with holographic recording using a frequency-doubled Nd:YAG laser (532 nm). The results showed that the 2-APB-based holographic sensors contracted upon addition of glucose due to the formation of a 2:1 complex between the tetrahedral 2-APB and glucose. More significantly, the 2-APB-based holographic sensors had greatly reduced lactate dependence and a hugely reduced pH effect over the physiological range of pH. These features are vital for development of contact lens-based glucose sensor, where the pH variability is greater (pH 5.8-7.8) and the lactate concentration is substantially higher than in blood. Furthermore, the 2-APB-based holographic sensors also displayed fast response to glucose. The successful union of holograms and the tetrahedral 2-APB receptor for glucose detection in artificial tear fluid is also demonstrated. This new type of holographic sensors responding to glucose with features of minor pH effect and negligible interference from lactate is applicable to the detection of glucose concentrations in tear fluid for the management of diabetes.

Congenital ectropion uveae (CEU) is a rare, non progressive anomaly characterised by the presence of iris pigment epithelium on the anterior surface and is frequently associated with anterior iris insertion, dysgenesis of the drainage angle and glaucoma. This paper describes an unusual case of bilateral congenital ectropion uveae with iris coloboma and telecanthus. The anterior chamber angle was normal and there was no evidence of glaucoma. To the best of our knowledge, this association has not been reported previously.

Purpose: To categorize the appearance of the normal upper palpebral conjunctiva using a grading scale and to investigate interobserver agreement with a grading scale modified to include decimal increments. Methods: Upper palpebral conjunctival appearance of 96 non-contact lens wearing subjects aged 18 to 75 years was assessed using a photographic grading scale that has a generic (zero to four) scale to score redness and roughness of the palpebral conjunctiva. Results: Median redness and roughness was about 1.25 units. About 5% of subjects had redness or roughness >2.0 units. Interobserver agreement improved during the study. By the end of the study, the standard deviation of the discrepancy scores was 0.12 to 0.19 units. Conclusions: Upper palpebral conjunctival redness or roughness >2.0 units are unusual. The grading scale can be used successfully with decimal rather than integer scale increments. For experienced clinicians, a change in grade of >0.5 units may be significant. (Optom Vis Sci 2001;78: 13-18)

Daily disposable contact lenses were introduced into the market 16 years ago. Data that we have gathered from annual contact lens fitting surveys conducted in Australia, Canada, Japan, The Netherlands, Norway, the UK and the USA between 2000 and 2008 indicates an overall increase in daily disposable lens fitting during this period. Daily disposable lenses are especially popular in Japan, Norway and the UK. There is a trend for these lenses to be fitted on a part-time basis. Males are over-represented in daily disposable lens fitting-a trend that is especially evident in Canada. Daily disposable lens wearers are about two years younger than wearers of reusable lenses in Japan and The Netherlands. The convenience and health benefits of daily disposable lenses are expected to fuel continued growth in this sector.

Aim: To determine the prevalence of contact lens related complications in a tertiary eye care centre in India. Methods: A retrospective review of the charts of 1255 patients who visited our contact lens clinic during 2001-2004 was conducted. The inclusion criteria included patients of at least 18 years of age, having refractive errors and keratoconus. Exclusion criteria included previous corneal surgeries and pediatric patients. 190 subjects with lens related complications were identified from among 923 patients who were using lenses. Results: The prevalence of contact lens complications was 20.58%. Females with complications were more common (59.47%). The complications were more common in students. The most common complications were contact lens induced papillary conjunctivitis (CLPC) (6.39%), corneal vascularisation (4%), and superficial punctate keratitis (SPK) (3.5%). The total complications were less prevalent in patients wearing rigid gas permeable (RGP) lenses as compared to soft contact lenses. Infectious keratitis was noted in 8 eyes. Pseudomonas aeuroginosa was the most common organism isolated. The average daily wear with RGP lenses was 11.04 ± 3.7 h and 10.96 ± 3 h with soft contact lens. The highest number of complications was noted in 47.89% patients who were wearing lenses for excess of 11 h. The number of patients with complications arising due to sleeping with the lenses was 74 (38.95%). Conclusion: Prevalence of contact lens complications was more in soft contact lens wearers compared to RGP wearers. CLPC was the most common complication followed by vascularisation and SPK.

This paper explains the liveness detection of the biometric system using the Face-Iris Images and deep learning classification. We have proposed novel hybrid algorithms for Face-Iris Liveness Recognition which can be used in cyber security authentication.In proposed model the individual identification is obtained from the extracted features that captured from face-Iris Images. Iris recognition is one of the most important biometric traits in which the iris image will be processed by some type of reliable, robust, and fast algorithm to capture the unique features embedded in iris. The camera system in which is used to capture the iris image will register depicts changes and variations in size of Iris as exposed to the light during the checkup and individual identification. This information will be used to verify the liveness of the iris image and distinguish the real lived iris image from the faked iris image. The recognition system based on the iris images are costly and required high resolution optical sensors and camera system beside the presence of the individual at the time of authentication and verification. The face image may change in certain degree such as appearance but shape and structure of face skeleton , location of eyes, mouth, and nose are remain unchanged. Due to this remarkable characteristic and ability to generate the face image features with near perfect identifiers and lack of requirement for physical contact with recognition system has made the facial recognition system remarkable. Our proposed face-iris feature extraction has been used to detect the fake face or iris from the real one and genuine live iris from the printed iris information by using the cosmetic lens. Our proposed model is based on the iris and face images in which high resolution camera and sensors are required at site to distinguish liveness Iris from fake one along with the high resolution algorithms that use combinations of DWT and SVD. The findings and results have shown the superiority our method,DWT-SVD, compared with hybrid of DCT, HT, MT with SVD, respectively. Our algorithm could be used to identify the fake Iris and face and greatly improve the cyber security. The extracted features can be obtained from videos or face images which have been captured from the scene even without individual physical contract. Our proposed model has been used for authentication and identification of the individuals based on the extracted features obtained from a new hybrid algorithm using both SVD and DWT.In proposed algorithm the face-iris features have been extracted and they are saved in the face-iris feature vectors for recognition. The Euclidian Distance vector has been used to classify the feature vectors extracted from live and fake face-iris images. The result and comparison of the proposed face-Iris recognition based on DWT-SVD with other technique has shown. Our method not only has higher speed of operation compared with other techniques but its rate of recognition is also good s as shown in the tabulated results.Experimental results also have shown that the hybrid methods of MT-SVD and HT-SVD have a better recognition results compared with DWT-SVD but their complex computation and extra time requirements for real time systems make them less important that DWT-SVD.

Cosmetic, or novelty, contact lenses are soft hydrogel lenses worn solely to change the colour or appearance of the eye. The popularity of these lenses is increasing worldwide, particularly amongst teenage adolescents. 1 Although possessing no optical power, these lenses pose the same physiological impact on the eye and carry the same risks as vision-correcting contact lenses.

To determine the long-term safety and effectiveness of laser in-situ keratomileusis (LASIK) in the treatment of refractive errors following penetrating keratoplasty (PK). A retrospective review was performed of 57 eyes of 48 patients with anisometropia or high astigmatism who were unable to wear glasses or a contact lens after PK and who underwent LASIK for visual rehabilitation. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BCVA), and corneal transplant integrity were recorded before surgery as well as up to 60 months after LASIK. The mean follow-up after the LASIK was 21.4 +/- 14.2 months (range 3 to 60 months). Mean preoperative spherical equivalent (SE) was -4.19 +/- 3.38 D. The mean preoperative astigmatism was 4.67 +/- 2.18 D. Preoperative BCVA was 20/40 or better in 42 eyes (74%). At 2 years the mean SE was -0.61 +/- 1.81 D, and mean astigmatism was 1.94 +/- 1.35 D for the 28 eyes with follow-up. UCVA was 20/40 or better in 12 eyes (43%), and BCVA was 20/40 or better in 24 eyes (86%) at 2 years. A gain in BCVA of 1 line or more was seen in 8 eyes (29%). Two eyes (7%) had loss of 2 or more lines of BCVA at 2 years. There were 9 eyes (16%) that developed epithelial ingrowth. Five eyes (9%) in this series had repeat corneal transplants. LASIK is effective for reducing ametropia after PK. Proper patient counseling is necessary because the results of LASIK after PK are not as good as, and complications are more frequent than in eyes with naturally occurring myopia and astigmatism. Complications are especially common in patients with mismatch of the donor and host cornea or in those with poor endothelial cell function.

PURPOSE: To demonstrate the use of the Quality of Life Impact of Refractive Correction (QIRC) questionnaire for comparing the quality of life of pre-presbyopic indi- viduals with refractive correction by spectacles, contact lenses, or refractive surgery. METHODS: The 20-item QIRC questionnaire was ad- ministered to 104 spectacle wearers, 104 contact lens wearers, and 104 individuals who had undergone re- fractive

Background Theoretically, the accommodative and vergence demands are different between single-vision contact lenses and spectacle lenses. The aim of the present study was to determine whether these differences exist when these two correction methods are used in clinical practice. For this, different visual parameters that characterize the accommodative (accommodation amplitude, accommodative facility, and accommodative response) and binocular function (near and distance horizontal and vertical dissociated phorias, near and vertical associated phorias, near and distance negative and positive fusional vergence, vergence facility, near point of convergence, negative and positive relative accommodation, stimulus AC:A ratio and stereoacuity) were evaluated in a student population when their myopia was corrected with either spectacles or soft contact lenses (SCL). Methods All parameters were measured on two separate occasions in 30 myopic habitual contact lens and spectacle wearers of mean age 19 ± 2.4 years. Some parameters such as accommodation amplitude, accommodative response, and stimulus AC:A ratio were measured using two measurement methods which are commonly used in clinical practice. Three measurements were taken for each parameter and averaged. For the comparative statistical analysis, we used the Student’s t-test (p value < 0.05). Results The following statistically significant differences were found with the use of SCL in comparison to spectacles: higher accommodative lags, higher negative relative accommodation, more esophoric near horizontal dissociated phoria, and lower negative fusional vergence in near vision. Conclusions The results found in this study show a definite trend towards poorer accommodative and vergence function with the use of contact lenses in comparison to glasses. This downward trend, though not statistically significant in accommodative function (lower PRA values and less lens amplitude of accommodation) might suggest that temporal insufficiency in the accommodation process could be occurring while contact lenses are used, thereby possibly creating a lag in accommodation to reduce associated overconvergence. This would be manifested in more esophoric values being found in the vergence function. The higher accommodative lags found in this study with SCL could indicate that prolonged use of SCL in near tasks may provoke a continuous hyperopic retinal defocus, a risk factor for the onset and progression of myopia, as indicated in numerous studies.

Purpose Effective contact lens disinfection solutions are important to keep the storage case free of acanthamoebae and thus prevent an infection of the eye. The aim of our study was to evaluate the effectivity of two new onestep hydrogen peroxide disinfecting solutions against Acanthamoeba spp. and compare it to the effectivity of other commercially available systems. Methods Nine one-step 3% hydrogen peroxide systems including the new systems Silver Sept (platinum and silver disk for intensifying disinfection) and Blue Vision (newly composed catalytic tablet) and 2 two-step systems (0.6 and 3.0% H 2 O 2 ) were tested for their effectivity against cysts of two Acanthamoeba keratitis isolates at different concentrations. Results After a soaking time of 8 h (overnight soaking of contact lenses) the 2 two-step systems completely destroyed the cysts of both Acanthamoeba strains, even at the highest concentration of cysts tested. The nine tested one-step systems showed weaker effects. The new Blue Vision system was able to eradicate the cysts of one strain at the low concentration of cysts. Conclusions One-step hydrogen peroxide systems do not have sufficient effects on Acanthamoeba cysts and therefore may not protect the contact lens user from a possible infection of the eye. Further development of tablets like the ones used in the Blue Vision system may result in better cysticidal effects for one-step systems.

Previous studies have demonstrated deposition of tear proteins onto worn contact lenses. In this study, we used proteomic techniques to analyze the protein deposits extracted from worn daily wear silicone hydrogel contact lenses in combination with different lens care solutions. Worn lenses were collected and protein deposits extracted using urea and surfactant. Protein extracts were desalted, concentrated, and then separated using one-dimensional gel electrophoresis. Individual protein components in extracts were identified using liquid chromatography combined with tandem mass spectrometry (LC-MS-MS) after trypsin digestion. One-dimensional gel electrophoresis revealed that lysozyme and other small proteins (around 20 kDa) were the most abundant proteins in the extracts. LC-MS-MS revealed a wide array of proteins in lens extracts with lysozyme and lipocalin 1 being the most commonly identified in deposit extracts. Worn contact lenses deposit a wide array of proteins from tear film ...

The visual outcomes for infants 18 months or younger with cataracts have improved dramatically over the past couple of decades. Earlier detection of infantile cataract and prompt surgical removal-with subsequent visual rehabilitation with contact lenses-mean that these patients now have a much better visual prognosis. Advances in contact lens technology have led to a significantly higher success rate with contact lenses and this has been a major factor in improving the visual outcomes for aphakic infants. This review outlines the contact lens management of infantile cataract, including a detailed analysis of the various contact lens options available and a discussion regarding the important factors that can cause issues with contact lens wear and affect the overall visual rehabilitation of the infant.

Background Theoretically, the accommodative and vergence demands are different between single-vision contact lenses and spectacle lenses. The aim of the present study was to determine whether these differences exist when these two correction methods are used in clinical practice. For this, different visual parameters that characterize the accommodative (accommodation amplitude, accommodative facility, and accommodative response) and binocular function (near and distance horizontal and vertical dissociated phorias, near and vertical associated phorias, near and distance negative and positive fusional vergence, vergence facility, near point of convergence, negative and positive relative accommodation, stimulus AC:A ratio and stereoacuity) were evaluated in a student population when their myopia was corrected with either spectacles or soft contact lenses (SCL). Methods All parameters were measured on two separate occasions in 30 myopic habitual contact lens and spectacle wearers of mean age 19 ± 2.4 years. Some parameters such as accommodation amplitude, accommodative response, and stimulus AC:A ratio were measured using two measurement methods which are commonly used in clinical practice. Three measurements were taken for each parameter and averaged. For the comparative statistical analysis, we used the Student’s t-test (p value < 0.05). Results The following statistically significant differences were found with the use of SCL in comparison to spectacles: higher accommodative lags, higher negative relative accommodation, more esophoric near horizontal dissociated phoria, and lower negative fusional vergence in near vision. Conclusions The results found in this study show a definite trend towards poorer accommodative and vergence function with the use of contact lenses in comparison to glasses. This downward trend, though not statistically significant in accommodative function (lower PRA values and less lens amplitude of accommodation) might suggest that temporal insufficiency in the accommodation process could be occurring while contact lenses are used, thereby possibly creating a lag in accommodation to reduce associated overconvergence. This would be manifested in more esophoric values being found in the vergence function. The higher accommodative lags found in this study with SCL could indicate that prolonged use of SCL in near tasks may provoke a continuous hyperopic retinal defocus, a risk factor for the onset and progression of myopia, as indicated in numerous studies.

The purpose of the article is to describe the optics of the contact wide-angle lens system with stereo-reinverter for vitreous surgery. A panoramic viewing system is made up of two components; an indirect ophthalmoscopy lens system for fundus image viewing, which is placed on the patient's cornea as a contact lens, and a separate removable prism system for reinversion of the image mounted on the microscope above the zooming system. The system provides a 104° field of view in a phakic emmetropic eye with minification, which can be magnified by the operating microscope. It permits a binocular stereoptic view even through a small pupil (3 mm) or larger. In an air-filled phakic eye, field of view increases to approximately 130°. The obtained image of the patient's fundus is reinverted to form true, erect, stereoscopic image by the reinversion system. In conclusion, this system permits wide-angle panoramic view of the surgical field. The contact lens neutralizes the optical irregularities of the corneal surface and allows improved visualization in eyes with irregular astigmatism induced by corneal scars. Excellent visualization is achieved in complex clinical situations such as miotic pupils, lenticular opacities, and in air-filled phakic eyes.

Purpose: Contact lens wearers today spend much time using digital display devices. Contact lens manufacturers are challenged to develop products that account for longer periods of time where blink rate is reduced and tear-film evaporation rate is increased, affecting both visual acuity and comfort.

Read this original research and sign up to receive Clinical Ophthalmology journal here: https://www.dovepress.com/articles.php?article_id=24264

Contact lens hygiene has long been recognised as key to the prevention of contact-lens associated infection and inflammation. Microbial keratitis (MK) is the only serious and potentially sight-threatening contact lens adverse event. International studies including recent research in Asia Pacific show that MK is rare but, as the consequences can be severe, it is important to minimise the risk factors. Studies continue to show that one of the key risk factors is lens and lens case hygiene. Therefore, it is also useful to review the behaviour of our patients, to see how closely they follow the recommended hygiene practices. Recent studies in various regions have shown that patients' lens care habits do not meet a required standard.

The ChromaGen lens system is designed to enhance colour perception in colour vision de®ciency (CVD). To investigate its ef®cacy, 14 CVD subjects were prescribed ChromaGen contact lenses. Colour vision tests (Ishihara, Farnsworth Munsell D-15, Farnsworth Lantern) were administered at baseline, lens dispensing, and after a 2-week lens-wearing trial during which subjective responses were recorded daily using visual analogue scales. ChromaGen lenses signi®cantly reduced Ishihara error rates p , 0:001; ANOVA), particularly for deutan subjects. There was also a signi®cant reduction in errors p , 0:005 on the D-15 test. Conversely, lens wear had no signi®cant effect on Farnsworth Lantern test performance. Subjectively, subjects reported enhanced colour perception, but poor vision in dim light. Judgement of distance and motion were only slightly affected. We conclude that ChromaGen lenses may enhance subjective colour experience and assist in certain colour-related tasks, but are not indicated as an aid for CVD in occupations with colour vision-related restrictions.

With estimated numbers of contact lens wearers worldwide exceeding 140 million, even complications with a low incidence will affect a significant number of individuals. Although contact lenses clearly have many advantages for wearers, certain risks have been associated with their use. Differences in risk for different types of contact lenses and wearing patterns have been demonstrated for both rare and common lens related complications. This review particularly focuses on the incidence and etiology of contact lens related corneal infection and inflammation. An understanding of the risks and contributory factors to these conditions is important for practitioners and will enable an informed choice of safer lens wear modalities, wear schedules, and hygiene regimes to be made. (Optom Vis Sci 2007;84:257-272)

Purpose: To analyse, retrospectively, the effect of fitting characteristics on comfort of wear and the role that 3D topographic data can play in attaining an optimal lens fit with rigid gas permeable (RGP) contact lenses in normal eyes. Methods: Included were 60 normal myopic eyes (1.00-5.00 D) with astigmatism limited to 2.00 D. Lenses were ordered empirically, based on traditional fitting rules. Results: The initial fit based on traditional computation was accepted in 40% of the eyes. To achieve an acceptable fit, 15% of the eyes needed an adaptation of the back optic zone radius, in 28% switching from a multicurve to an aspheric lens design was indicated and in 17% a non-rotational symmetric lens design was favoured. The reason for changing the lens parameters could in 88% be attributed to mid-peripheral differences between corneal shape as found with 3D corneal topography. Average comfort of wear improved statistically significantly (χ 2 , P < 0.05) from 5.2 initially to 7.7 after 3 months in the group with optimal lens fits, while comfort slightly decreased (not significant) in the group with sub-optimal fits. Switching to a non-rotational symmetric lens design, when indicated, improved comfort significantly (χ 2 , P < 0.05) from 5.0 to 7.3. Conclusion: In normal eyes, the measurement of corneal shape, especially in the mid-peripheral regions, is of importance to optimise RGP lens fit. Optimised lens fits increases comfort of wear.

Zusammenfassung. Hintergrund.• Die Verwendung von Leitungswasser bei der Kontaktlinsenhandhabung gilt als Risikofaktor fur eine Infektion mit Akanthamoben [10, 17]. Es ist anzunehmen, dass der kontaminierte Aufbewahrungsbehalter haufig der auslosende Faktor fur eine Infektion des Auges ist [9]. Welches Risiko geht jener osterreichische Augenarzt ein, der Leitungswasser zur Hartlinsenspulung and Behalterreinigung miteinbezieht, and worm liegen die Vorteile von Leitungswasser? Patienten and Methode: 150 Kontaktlinsenbehalter von asymptomatischen Kontaktlinsentragern wurden auf das Vorhandensein von Akanthamoben untersucht. 45 Behalter stammten von Weich-and 105 von Hartlinsentragern. Allen Patienten war die Verwendung von Leitungswasser entweder zur Hartlinsenspiilung oder zur Behalterreinigung erlaubt. Ergebnisse: In 1 von 150 untersuchten Aufbewahrungsbehaltern konnten Akanthamoben (A. palestinensis) nachgewiesen werden. Das Alter dieses Weichlinsenbehalters wurde mit 4 Jahren angegeben. Schon makroskopisch war dieser Behalter stark verunreinigt, and ein MindesmaB an Hygiene and Pflegeaufwand wurde von der Kontaktlinsentragerin nicht erfiillt. Schlussfolgerung: Aus den Ergebnissen unserer Studie geht kein negativer Effekt bei der Verwendung von Leitungswasser zur Hartlinsenspulung and Kontaktlinsenbehalterreinigung hervor. Die Pflege des Behalters (mechanische Reinigung, Auskochen des Behalters, haufige Erneuerung) sollte jedoch mit ebenso groBem Aufwand betrieben werden wie die Kontaktlinsenpflege selbst. Die Verwendung von Desinfektionslosungen, welche gegen Akanthamobentrophozoiten und -zysten wirksam sind, istjedenfalls zu empfehlen. Schliisselworter: Akanthamoben, Leitungswasser, Kontaktlinsenbehalter.

We investigated the effect of high Dk daily wear rigid gas permeable contact lenses on corneal topography. Eight young myopic subjects wore hard contact lenses for 21 days. Corneal topography was monitored using the EyeSys system. It was measured every day during the next 21 days after the ®tting. We recorded the corneal radius of curvature at 16 peripheral points approximately 1, 2, 3 and 4 mm along the four principal meridians (nasal, superior, inferior and temporal). Our study showed that daily wear RGP Forum 210 does not produce signi®cant alterations of the corneal curvature as a function of time. q

Las queratitis infecciosas poseen una elevada morbilidad, poniendo en riesgo la visión en casos graves. Dada la eficaz protección que brinda el epitelio corneal, para que ocurra una infección se requiere la presencia de factores condicionantes. El principal predisponente para las queratitis infecciosas es el uso de lentes de contacto, seguido por traumatismos y cirugías oculares y luego diversas afecciones locales o generales. Los agentes etiológicos abarcan una enorme diversidad de microorganismos, incluyendo bacterias, micobacterias, virus, hongos y parásitos. Para poder instaurar un tratamiento acotado se necesita un diagnóstico etiológico, lo que requiere una correcta toma de muestra y un exhaustivo análisis microbiológico.

Acanthamoeba are free-living, harmless organisms, however, given the opportunity and the appropriate conditions, they can cause painful, sight-threatening as well as fatal infections and, thus, are considered opportunistic pathogens. Acanthamoeba infections have become increasingly important in the past few years due to increasing populations of contact lens users and AIDS patients. The mechanisms associated with the pathogenesis of Acanthamoeba tend to be highly complex, depending on parasite, host and the environmental factors. Elucidation of the biochemical, cellular and molecular basis of the pathogenesis of diseases caused by Acanthamoeba may lead to the development of therapeutic interventions. q

Purpose Survey the actual clinical practice of pediatric visual electrophysiology. The electrophysiologists surveyed were members of the International Society for Clinical Electrophysiology of Vision (ISCEV). Methods A self-administered questionnaire with 55 items about visual evoked potential (VEP) and electroretinogram (ERG) testing of pediatric patients was sent to ISCEV members. The survey queried personnel, facilities, referral patterns and conduct of tests.

Purpose. Lid wiper epitheliopathy (LWE) and lid parallel conjunctival folds (LIPCOF) give moderate prediction levels for dryness symptoms in experienced contact lens (CL) wearers. This study investigated whether a combination of LWE and LIPCOF plus other tear film tests and subjective evaluation before contact lens fitting was better able to predict CL-induced dry eye (CLIDE) symptoms. Methods. Tear meniscus height, non-invasive break-up time (NIBUT), ocular hyperaemia, LIPCOF, phenol red thread test, corneal and conjunctival staining, and LWE of the right eye of 33 new soft CL wearers (12 males, 21 females, median age ϭ 30.5 years; range ϭ 19 to 44) were assessed in a prospective 2-mo longitudinal study. Symptoms were evaluated by the Ocular Surface Disease Index (OSDI) and subjects were grouped according to their response in the Contact Lens Dry Eye Questionnaire (CLDEQ) during the study (20 symptomatic and 13 asymptomatic). The subjects were fitted with vifilcon A and senofilcon A lenses for a 2-week period, consecutively. Results. Limbal hyperaemia (repeated measures analysis of variance; p Ͻ 0.05) and LWE (Friedman; p Ͻ 0.004) increased significantly during the study but not LIPCOF (p Ն 0.318; temporal, nasal, and Sum), bulbar hyperaemia (p ϭ 0.432), staining (p Ն 0.060), OSDI (p ϭ 0.126), or CLDEQ (p ϭ 0.317, ϭ 0.279). Limbal hyperaemia significantly decreased in senofilcon A lenses. Wearing comfort among symptomatics was significantly better with senofilcon A (p ϭ 0.005). At the enrolment visit, the subjects who became symptomatic exhibited significantly decreased NIBUT and increased LIPCOF and OSDI (range, p Ͻ 0.027). The best test combination to predict CLIDE (logistic regression analyses) was LIPCOF Sum plus NIBUT and OSDI, (positive predictive value ϭ 87% and accuracy ϭ 91%). Conclusions. LIPCOF, NIBUT, and OSDI are significant discriminators for CLIDE in new CL wearers compared with hyperaemia, tear meniscus height, phenol red thread test, staining, and LWE. The best test combination is NIBUT plus LIPCOF Sum and OSDI (named the Contact-Lens-Predicting-Test).

Although previous studies suggest that orthokeratology contact lens wear slows eye growth in children with progressing myopia, some limitations in the methodology employed have become evident. Furthermore, the safety of this modality of visual correction has not been assessed. The study "Myopia Control with Orthokeratology Contact Lenses in Spain" (MCOS) is being conducted to compare axial length growth between white European myopic children wearing orthokeratology contact lenses (OK) and wearing distance single-vision spectacles (SV). Additionally, the incidence of adverse events and discontinuations is also recorded. We outline the methodology and baseline data adopted. METHODS: Subjects aged 6 to 12, with myopia ranging from 0.75 to 4.00 D and astigmatism ≤1.00 D were prospectively allocated OK or SV correction. Measurements of axial length, anterior chamber depth, corneal topography, cycloplegic autorefraction, visual acuity and corneal staining are performed at 6-month intervals. The incidence of adverse events and discontinuations are also recorded. RESULTS: Thirty one children were fitted with OK and 31 with SV correction. Eight subjects did not meet the refraction-related inclusion criteria for enrollment. No significant differences were found in baseline mean age and refractive and biometric data between the two groups (P>0.05). No adverse events were found in any of the two groups at baseline. CONCLUSION: To the authors' knowledge, MCOS is the first prospective clinical trial to assess the safety and efficacy of orthokeratology contact lens wear to slow myopia progression vs. single-vision spectacle wear. The MCOS offers a number of notable features: prospective design; well-matched samples and high-resolution ocular biometry measures, which should collectively elucidate whether orthokeratology contact lens wear is a feasible and safe method for myopia-progression control. (J Optom 2009;2:215-222

Purpose: To evaluate the efficacy, predictability, stability, and safety of the surgical correction of high myopia using a phakic posterior chamber intraocular lens (PPC IOL).Setting: Centro Oftalmológico de Valencia-CEOVAL, Valencia, Venezuela.Methods: A retrospective study was performed to analyze 18 eyes of 12 patients who had implantation of a modified PPC IOL, the implantable contact lens (ICL), for the treatment of high myopia. The target postoperative spherical equivalent (SE) refraction was emmetropia.Results: The mean follow-up was 26.6 months ± 11.3 (SD) (range 12 to 36 months). The mean preoperative SE was −15.27 ± 3.47 diopters (D) (range −10.0 to −21.25 D) and the mean postoperative SE, −0.62 ± 0.81 D (range −2.75 to +0.75 D). Eleven eyes (61.1%) had an SE within ±1.00 D of emmetropia. The best spectacle-corrected visual acuity was maintained or improved in all except 1 eye, which lost more than 2 lines of Snellen visual acuity. Two eyes (11.1%) developed pupillary block the first day after surgery. Four eyes (22.2%) had moderate pigmentary dispersion. Two eyes (11.1%) had lens opacification, 1 with mild peripheral anterior capsule opacification and the other eye with central anterior subcapsular opacification. One eye (5.5%) had a significant decrease in anterior chamber depth after surgery.Conclusions: Implantation of an ICL was effective for the correction of high myopia. Predictability must be improved and the long-term safety of the ICL determined. The main concerns over potential cataract formation, pigmentary dispersion, and angle-closure glaucoma remain.

Purpose: Spectral optical coherence tomography (SOCT) is a new non-invasive, non-contact, highresolution technique, which provides cross-sectional images of objects that weakly absorb and scatter light. The aim of this article is to demonstrate the application of SOCT to imaging of eyes fitted with contact lenses. Methods: Nine eyes of six different subjects fitted with various contact lenses have been examined with a slit-lamp and a prototype SOCT instrument. Results: Our SOCT system provides high-resolution (4-6 lm longitudinal, 10 lm transversal) tomograms composed of 3000-5000 A-scans with acquisition time of 100-250 ms. The quality of the images is adequate for detailed evaluation of contact lens fit. Design, shape and lens edge position were assessed, and complications of contact lens wear could be visualized. Thickness of the lens, corneal epithelium and stroma as well as the space between the lens and the eye surface have been measured. Conclusions: SOCT allows high-resolution, cross-sectional visualization of the eye fitted with a contact lens. The ability to carry out a detailed evaluation of the fitting relationship between the lens and the ocular surface might be useful in research and optometric practice. SOCT can also be helpful in diagnosis, evaluation and documentation of contact lens complications.

Purpose: Testing whether the extended depth of focus technology embedded on non-toric contact lenses is a suitable treatment for both astigmatism and presbyopia. Methods: The extended depth of focus pattern consisting of microndepth concentric grooves was engraved on a surface of a mono-focal soft contact lens. These grooves create an interference pattern extending the focus from a point to a length of about 1mm providing a 3.00D extension in the depth of focus. The extension in the depth of focus provides high quality focused imaging capabilities from near through intermediate and up to far ranges. Due to the angular symmetry of the engraved pattern the extension in the depth of focus can also resolve regular as well as irregular astigmatism aberrations. Results: The contact lens was tested on a group of 8 astigmatic and 13 subjects with presbyopia. Average correction of 0.70D for astigmatism and 1.50D for presbyopia was demonstrated. Conclusions: The extended depth of focus technology in a non-toric contact lens corrects simultaneously astigmatism and presbyopia. The proposed solution is based upon interference rather than diffraction effects and thus it is characterized by high energetic efficiency to the retina plane as well as reduced chromatic aberrations.

Purpose: To investigate the sequence of morphologic changes over time in cat epithelium during continuous wear of orthokeratology lenses. Methods: Four 2-year-old female cats were used; one served as a no lens wear control and three wore custom designed Paragon CRT lenses for myopic and hyperopic correction in the right and left eyes, respectively. Lenses were worn continuously and animals were euthanased after 4 h, 8 h and 14 days. Corneal tissue was fixed then stained with hematoxylin and eosin for histologic evaluation and measurement of epithelial thickness. Results: Average epithelial thickness of control eyes in the centre (38 AE 1 mm) and mid-periphery (3.0 mm from the centre, 38 AE 2 mm) of the cornea was similar. Epithelial thickness in myopic corrected eyes showed progressive thinning in the centre and progressive thickening in the mid-periphery with increased lens wearing time. Hyperopic corrected eyes showed the opposite pattern of progressive epithelial thickening in the centre and thinning in the mid-periphery with lens wearing time.

Perfluorocarbon liquids have been used to facilitate surgery in a wide variety of conditions, including proliferative vitreoretinopathy, giant retinal tears, drainage of suprachoroidal hemorrhages, diabetic traction, retinal detachments with a rhegmatogenous component, dislocated crystalline or intraocular lenses, and retinal detachment associated with choroidal coloboma. The clarity of perfluorocarbon liquids, with a refractive index close to that of water, allows the use of a conventional contact lens for vitreous surgery while the low viscosity facilitates tissue manipulation, injection, and removal. All perfluorocarbon liquids when used as tamponading agents can compress and disorganize the retina. This "toxicity" is a physical effect rather than chemical toxicity and depends upon the amount of perfluorocarbon liquid injected. Perfluorocarbon liquids are not tolerated in the anterior chamber, causing corneal edema within 2-3 days at the site of contact. (Surv Ophthalmol 39: 1995) Key words, perfluorocarbon liquids 9 retinal detachment ~ vitreous substitutes

Purpose: To report longer term results of transscleral sutured intraocular lens (TSSIOL) implantation in a sizable cohort of aphakic children, who were not suitable for contact lens wear and lacked adequate capsular support for sulcus fixation of an intraocular lens. Methods: Clinical outcome data were collated by retrospective review after surgery on 43 consecutive eyes in 32 aphakic children (mean age at implantation ϭ 10 years; 33% Յ age 7 years). Outcome measures included visual acuity, postoperative refractive error, postoperative complications, and rate of reoperation. Follow-up averaged 37 months. Results: Visual acuity improved after surgery in 70% (30) of operated eyes (in 69% or 22/32 children). Fifty-one percent (22/43 eyes) improved by two lines or more. No patient suffered a loss of acuity or exacerbation of preexisting amblyopia. Postoperative refraction was within Ϯ2.0 D of the predicted refraction in 93% (40/43) of eyes. Complications, with the exception of one eye (2%), were minor/transient and resolved in the first week after surgery. Complications included small hyphemas (7%, 3/43 eyes), vitreous hemorrhage (5%, 2/43 eyes), and ocular hypertension or hypotony (5%). Two eyes (5%) exhibited episodes of iris capture of the IOL optic, one of which (2%, 1/43) eventually necessitated reoperation for IOL exchange. No retinal detachments or other retinal complications were encountered. Conclusion: TSSIOL implantation appears to be a safe and effective method for correcting aphakia in pediatric eyes that lack adequate capsular support. Safety over a follow-up period longer than the average 3 years reported here remains to be determined. The surgery is more difficult to perform than capsular-bag or sulcus implantation and potentially carries greater risks. (J AAPOS 2004;8:318-324)

Objective To evaluate subjective symptoms and clinical signs of tolerability and comfort in silicone and non-silicone hydrogel contact lens (CL) wearers using two different multipurpose solution (MPS) CL care regimens. Methods This was a randomized, double-masked, contralateral, crossover, multicenter (n=9) study. One hundred and eleven subjects were enrolled in the study, and were randomly assigned either silicone hydrogel CLs or non-silicone hydrogel CLs. Before wear, the CLs were randomly conditioned for at least 10 hours in a multipurpose disinfection solution (MPDS) preserved with either: Regimen 1-polyquaternium-1 0.001% and myristamidopropyl dimethylamine 0.0005% (POLYQUAD® and ALDOX®, respectively; OPTIFREE EXPRESS® MPDS, Alcon Laboratories, Inc., Fort Worth, TX, USA); or Regimen 2-multipurpose solution preserved with polyhexamethylene biguanide 0.0001% (PHMB, ReNu MultiPLUS® MPS, Bausch & Lomb, Rochester, NY, USA). The study had two in-office visits, 1 week apart. Subjects wore assigned CLs for approximately 4 hours at each visit. At each visit, subjects’ eyes were examined before CL insertion and at 2 hours and 4 hours after insertion. Corneal staining type and area, conjunctival staining, conjunctival injection, subjective symptoms (tolerability), and comfort were evaluated. Results One hundred and five subjects (210 eyes) completed the study. The total corneal staining score of area and type were statistically significantly less in Regimen 1 than in Regimen 2 (P<0.000001). The area of conjunctival staining was statistically significantly less in Regimen 1 than in Regimen 2 (P=0.03). No clinically significant hyperemia was observed for either regimen. Both tolerability (P=0.02) and patient preference (P=0.05) were in favor of Regimen 1. Conclusions Statistically significant clinical differences were evident between the two CL care regimens when used with silicone and non-silicone hydrogel CLs. OPTI-FREE EXPRESS MPDS users showed less corneal and conjunctival staining and reported greater comfort and tolerability to the CL/solution combination than ReNu MultiPLUS MPS users.