Disposable Soft Contact Research Articles

Swimming with soft contact lenses: danger of acanthamoeba keratitis

A 25-year-old woman sought medical advice on experiencing sudden pain and blurred vision in her right eye. She was a swimming instructor and swam with daily disposable soft contact lenses and swimming goggles. The initial diagnosis was herpetic keratitis. Topical and systemic antibiotics and aciclovir were administrated but were ineffective. When referred to Tsukuba University Hospital, she had severe eye pain and visual acuity had decreased to hand motion. Slit-lamp examination revealed corneal stromal opacity due to severe corneal inflammation (figure, A).

Dispersion of microemulsion drops in HEMA hydrogel: a potential ophthalmic drug delivery vehicle

Approximately 90% of all ophthalmic drug formulations are now applied as eye-drops. While eye-drops are convenient and well accepted by patients, about 95% of the drug contained in the drops is lost due to absorption through the conjunctiva or through the tear drainage. A major fraction of the drug eventually enters the blood stream and may cause side effects. The drug loss and the side effects can be minimized by using disposable soft contact lenses for ophthalmic drug delivery. The essential idea is to encapsulate the ophthalmic drug formulations in nanoparticles, and disperse these drug-laden particles in the lens material. Upon insertion into the eye, the lens will slowly release the drug into the pre lens (the film between the air and the lens) and the post-lens (the film between the cornea and the lens) tear films, and thus provide drug delivery for extended periods of time. This paper focuses on dispersing stabilized microemulsion drops in poly-2-hydroxyethyl methacrylate (p-HEMA) hydrogels. The results of this study show that the p-HEMA gels loaded with a microemulsion that is stabilized with a silica shell are transparent and that these gels release drugs for a period of over 8 days. Contact lenses made of microemulsion-laden gels are expected to deliver drugs at therapeutic levels for a few days. The delivery rates can be tailored by controlling the particle and the drug loading. It may be possible to use this system for both therapeutic drug delivery to eyes and the provision of lubricants to alleviate eye problems prevalent in extended lens wear.

Accuracy of intraoperative retinoscopy in corneal power and axial length estimation using a high plus soft contact lens

To assess the accuracy of intraoperative retinoscopy with high plus soft contact lens (CL) in estimating corneal power and the axial length compared with standard keratometry and biometry measurement. Intraoperative retinoscopy was performed in 30 eyes prior to the implantation of an intraocular lens (IOL). A +10 D disposable soft contact lens was applied on the cornea to minimize retinoscopic error. Corneal power was derived from refraction using biometric axial length while the axial length was derived using keratometric measurement. Refraction derived corneal powers and axial lengths from 26 eyes within +/-1.00 D of the target postoperative refraction were compared with preoperative standard keratometry and biometry measurements. In the 26 eyes, the mean difference between the corneal powers derived from refraction and keratometry was 0.35 D (S.D.=1.678). The 95% limits of agreement were -3.006 to +3.706. The mean difference between the axial lengths derived from refraction and biometry was 0.15 mm (S.D.=0.721). The 95% limits of agreement were -1.292 to 1.542. Intraoperative retinoscopy with a high plus soft contact lens after phacoemulsification is useful but not accurate in estimating corneal power or axial length of the eye. It should be used cautiously in IOL power calculation as a substitute for standard keratometry or biometry machines when either of these is not available or in error.

Contact Lens Assisted Pharmacologically Induced Keratoshaping

To retrospectively evaluate the effectiveness and describe the process of reducing hyperopia with a nonsteroidal antiinflammatory agent and a soft disposable contact lens in postoperative excimer laser patients with consecutive hyperopia. Private practice. This study includes a retrospective analysis of 14 eyes of 12 patients who underwent laser in situ keratomileusis or photorefractive keratectomy and experienced consecutive hyperopia. Patients were treated with a tightly fit, extended-wear contact lens in combination with the use of ketorolac tromethamine 0.5% (Acular) in an attempt to steepen the cornea. Uncorrected visual acuity, manifest refraction, and slitlamp examination were performed on a weekly basis until the desired outcome was achieved or until treatment was discontinued. A total of 78.57% of eyes experienced a decrease in consecutive hyperopia (>or=0.50 diopters [D]) (P = 0.002). The mean dioptric change was 1.05D. A total of 88.89% of eyes experienced an increase in uncorrected visual acuity (>or=1 line) (P < 0.001). The mean increase was three lines of Snellen or Jaeger acuity. The mean number of weeks to see an effect was 1.71 weeks, and the mean number of weeks to achieve endpoint was 8.29 weeks (median, 6 weeks). CONCLUSIONS.: Contact lens-assisted pharmacologically induced keratoshaping is an effective treatment option for patients who experience consecutive hyperopia after laser in situ keratomileusis or photorefractive keratectomy.

Kératite fongique et lentilles cornéennes jetables journalières

A case of fungal keratitis was diagnosed in a young female who had been wearing daily disposable soft contact lenses for 2 Years. No risk factor was demonstrated and specific treatment was effective. This case emphasizes that patients must be aware of the importance of hygiene as daily disposable contact lenses must be discarded daily.

Confocal microscopic observations of the human cornea following overnight contact lens wear

Background: Striae and folds are observed with a slidamp biomicroscope in the cornea following overnight contact lens wear. These phenomena are poorly understood. The aim of this study is to employ confocal microscopy to observe and document these and other morphological changes in die human cornea following overnight contact lens wear. Methods: Slitlamp biomicroscopy, slit‐scanning confocal microscopy and ultrasonic pachometry were performed on both eyes of 13 subjects (3M, 10F, age 24 ± 3 years) before and after eight hours overnight wear of a ‐3.00 D Bausch & Lomb one day disposable soft contact lens (Dk/t = 15.1 times 10‐9 (cm/sec) x {ml O2/ml x mmHg)) in one eye; the other non‐lens‐wearing eye acted as a control. Results: Following sleep, both corneas were swollen (lens‐wearing eye 11.8 ± 3.8 per cent; control eye 2.1 ± 1.9 per cent) and the stroma of both corneas displayed an apparent reduction in keratocyte density (lens‐wearing eye 21 per cent; control eye 10 per cent). Folds were observed with the slidamp biomicroscope and long, straight, dark, orthogonal lines were observed widi die confocal microscope, in the posterior stroma of the oedematous lens‐wearing eyes. Such features were not observed in die control eyes. The keratocytes appeared less distinct with greater levels of corneal oedema. Conclusion: The apparent loss of keratocytes following overnight lens wear is an optical artefact that can be explained in terms of corneal oedema causing volumetric tissue expansion and a loss of optical clarity, which hampers keratocyte detection. These findings place the onus on researchers postulating a loss of stromal keratocytes following clinical interventions, such as contact lens wear, to account for the effects of oedema.

Contact lens induced keratitis associated with contact lens wear.

To evaluate clinical characteristics, risk factors, management and outcome of contact lens induced keratitis (CLIK) associated with contact lens wear. The study comprised all consecutive patients presenting with contact lens related presumed microbial keratitis during a 12-month period at our department. Detailed demographic data, type of contact lens, duration of lens wear, wearing schedule and lens hygiene were derived from a self-administered questionnaire. Severity of ulcer, corneal scrapings, treatment and final outcome were evaluated. 27 patients with CLIK, some of which may have been sterile peripheral infiltrates, due to contact lens wear were detected. In the majority of the cases patients had used disposable soft contact lenses (89%) and most of them had a daily wearing schedule (78%). 51.8% patients cleaned their lenses regularly. 6 (22%) applied no disinfection since their lenses were disposable on removal. In 3 of our cases with CLIK, penetrating keratoplasty had to be performed. Disposable contact lenses seem to have been a predisposing factor for contact lens induced keratitis also when used on a daily wear schedule. Insufficient contact lens care products and/or manufacturing characteristics may be responsible for CLIK, which is also observed in otherwise compliant contact lens users. In 3 of our patients with CLIK keratoplasty became necessary, indicating that contact lens induced keratitis may result in severe corneal complications.

Condições de adaptação e venda de lentes de contato em óticas do estado de São Paulo

Objetivo: Avaliar as condições de adaptação e venda de lentes de contato (LC) em óticas de quatro cidades do Estado de São Paulo, Brasil. Métodos: Realizou-se estudo por meio de respostas a um questionário aplicado por quatro estudantes de Medicina em óticas situadas em várias cidades do Estado de São Paulo. Foram obtidos dados sobre a necessidade da apresentação de receita médica para a compra das LC, os tipos de LC vendidas/adaptadas, o profissional que orienta a venda e/ou adaptação, os equipamentos usados no teste de tolerância, a conduta do cliente diante de complicações quando da adaptação da LC ou durante o uso, orientação quanto a possíveis sinais e sintomas de perigo, as doenças que contra-indiquem o uso e a higiene do usuário, as horas de uso e a possibilidade de pernoite. Resultados: Das 198 óticas pesquisadas, 121 (61,11%) vendem LC. Não foi necessária receita médica para a compra das lentes em 112 óticas (92,56%), sendo que nessas, a graduação era determinada pela medida dos óculos em 69 (61,61%) casos e por relato verbal em 28 (25,00%) casos. Quanto aos equipamentos, 102 (91,07%) óticas possuíam lensômetro; 41 (36,61%) possuíam ceratômetro e 14 (12,50%), lâmpada de fenda. Lentes descartáveis hidrofílicas foram encontradas para venda/adaptação em 66 (54,55%) óticas; lentes hidrofílicas de uso prolongado ou diário em 68 (56,20%) e lentes rígidas, em 54 (44,63%). Em 103 (85,12%) óticas, foram feitos testes de tolerância, sendo os responsáveis pelo atendimento e pela monitorização dos testes os profissionais autodenominados contatólogos em 78 (64,46%) dessas óticas, balconista em 20 (16,53%), óptico em 12 (9,92%) e oftalmologistas em 9 (7,44%). Quanto às complicações na adaptação, em 66 (54,55%) óticas, afirmou-se que elas só ocorreriam, se evidenciadas no teste de tolerância; em 35 (28,93%), aconselhou-se tratamento com oftalmologista e em 20 (16,53%), sugeriu-se o retorno à ótica para indicação de tratamento. Em apenas 15 (13,39%), o profissional orientou quanto à possível sintomatologia de perigo e em 13 (11,61%), preocupou-se com doenças que contra-indicassem o uso de LC. Em 105 (93,75%) óticas, a orientação foi insuficiente em relação à higiene com as LC, às horas de uso e à possibilidade de pernoite. Conclusão: Das 198 óticas pesquisadas, 61,11% vendem lentes de contato, sendo que em 92,56% não foram solicitadas receitas médicas; 14,88% não fizeram qualquer tipo de teste de tolerância e as óticas restantes (85,12%) fizeram testes normalmente insuficientes para detecção de alterações induzidas por LC. Não houve preocupação com contra-indicações, sinais e sintomas de perigo nem avaliação de possíveis complicações pela presença das LC e conduta em caso de sua ocorrência, além dos cuidados mínimos de higiene durante o teste de tolerância. O profissional responsável pela adaptação (autodenominado contatólogo, balconista, ótico; ou oftalmologista) não forneceu orientação adequada sobre o uso e, em muitos casos, não deu orientação em relação à higiene.

Influence of the luminance level on visual performance with a disposable soft cosmetic tinted contact lens

The purpose of the present work was to study the effect on visual performance of wearing disposable soft tinted contact lenses for cosmetic purposes. Parameters such as contrast sensitivity (Vistech 6000), colour vision (Farnsworth-Munsell 100-Hue colour test), visual fields (static Goldmann perimetry) and subjective vision (what the wearer feels while wearing the lenses) were studied under different illumination levels in order to check for possible vision losses while wearing these contact lenses at low illumination levels. Sixteen emmetropic subjects were fitted consecutively with seven pairs of different colour lenses (Optima Colors® lenses by Bausch & Lomb), and the experimental parameters were measured under four different illumination levels (60, 6, 1, and 0.1cd/m2; but 15 and 0.3cd/m2 for the static perimetry) The results obtained showed no statistically significant differences in visual performance between wearing the lenses and not wearing them (p>0.01), except for the static perimetry, in which statistically significant differences (p<0.01) occur at eccentricities greater than 30°.

Bacterial colonization of disposable soft contact lenses is greater during corneal infiltrative events than during asymptomatic extended lens wear.

Microorganisms, especially gram-negative bacteria, are considered to play a role in the etiology of certain corneal infiltrative events (CIEs) observed during soft contact lens wear. This study explored the possibility of microbial colonization of soft contact lenses as a risk factor leading to CIEs. In a clinical trial conducted from March 1993 to January 1996, 330 subjects wore disposable soft contact lenses on a 6-night extended-wear and disposal schedule. During this period, 4,321 lenses (118 during CIEs; 4,203 during asymptomatic lens wear) were recovered aseptically and analyzed for microbial colonization. A greater percentage of lenses were free from microbial colonization during asymptomatic wear than during CIEs (42 versus 23%; P < 0.0001). The incidence of gram-positive bacteria, gram-negative bacteria and fungi was greater during CIEs than during asymptomatic lens wear (P < 0.05). During asymptomatic lens wear, gram-positive bacteria were isolated most frequently and were usually normal external ocular microbiota. Of the gram-positive bacteria, the incidence of Streptococcus pneumoniae was greater during CIE than during asymptomatic wear (7.6 versus 0.6%; P < 0. 0001). While gram-negative bacteria were seen in few cases during asymptomatic wear, their incidence during CIE in comparison to asymptomatic wear was substantial and significant (23.7 versus 3.8%; P < 0.0001). Also, the level of colonization was high. Of CIEs, events of microbial keratitis, contact lens acute red eye, and asymptomatic infiltrative keratitis were associated with lens colonization with gram-negative bacteria or S. pneumoniae. Colonization of soft contact lenses with pathogenic bacteria, especially gram-negative bacteria and S. pneumoniae, appears to be a significant risk factor leading to CIE.

Presbyopic contact lenses

The year 1999 will be remembered as the one in which a very successful bifocal soft contact lens was finally available for the millions of presbyopic and emerging presbyopic Baby Boomers. As a result, soft bifocal fits almost tripled in 1 year. The introduction in 1999 of new daily disposable and new high oxygen permeable extended wear soft contact lenses will give practitioners more options to be successful with monovision. Tips from several practitioners on being successful with bifocal soft lenses are given. It cannot be stressed enough, however, that for patients with presbyopia to be successful with these lenses, they must be willing to compromise somewhat on the quality of vision they remember as a 30-year-old.

Ultraviolet transmittance of the vistakon disposable contact lenses

With increasing scientific evidence demonstrating the harmful effects of ultraviolet (UV) radiation on different ocular tissues, contact lens manufacturers are incorporating UV blocking monomers into their contact lenses. This study evaluated the transmittance spectra of Vistakon's disposable soft contact lenses (1 Day Acuvue, Acuvue, Surevue, and Vistavue). All except Vistavue contain a UV blocking agent. Transmittance for each lens was recorded from 200 to 400 nm on a Shimadzu UV 160U Dual Beam Recording Spectrophotometer. The results indicate that lenses which incorporate the UV blocking monomer significantly reduced the transmission of W radiation while untreated lenses did not. Our findings indicate that 1 Day Acuvue, Surevue, and Acuvue meet the American National Standards Institution (ANSI) Standard Z80.20 for Class 2 UV blockers: a maximum of 30% transmittance of UVA wavelengths and 5% transmittance of UVB wavelengths. In contrast, the Vistavue lens demonstrated negligible UV blockage. Our technique, in which contact lenses were placed directly in front of a measuring beam, was accurate and simpler than previously reported methods and may be useful in future studies. We found that UV blocking soft contact lenses can be a viable alternative for spectacles in protecting internal ocular structures from UV radiation. However, the external structures of the eye remain at risk and would continue to benefit from the use of UV blocking sunglasses or spectacle lenses.

Clinical performances of two disposable soft contact lenses of different materials on Hong Kong-Chinese

Dryness due to contact lens wear and poor wetting of contact lenses among contact lens wearers is a common observation and contact lens manufacturers have introduced new, better quality soft lens materials that are claimed to be more deposit resistant, and/or dehydration resistant. The purpose of this study was to evaluate and compare the clinical performance of Hydron ActiSoft 60§, made of a new material (HyGMA™) which is claimed to be dehydration resistant with excellent wettability, with ActiFresh 400, made of conventional non-ionic hydrogel material. The experiment was conducted as a double-masked, randomised, cross-over study. Clinical assessment included pre-lens non-invasive tear break up time (PL-NITBUT), logMar visual acuity and contrast sensitivity (CS). Corneal staining, if any, was recorded at each visit. Subjective ratings in regard to dryness, grittiness, lens awareness, vision, comfort, handling (removal), handling (cleaning) and the overall preference of each lens type were obtained at the end of 3 (Phase A) and 6 months' (Phase B) wear. Twenty-eight subjects successfully completed the study. In Phase A, no significant differences were found in both baseline PL-NITBUT and PL-NITBUT after wearing the same lenses for 1 month between the two lens types. In phase B, baseline PL-NITBUT for ActiFresh 400 was significantly shorter than that for ActiSoft 60. However, after 1 month of wear, the difference in PL-NITBUT between the two lens types was no longer significant. PL-NITBUT was significantly reduced after 1 month's wear for both ActiSoft 60 and Actifresh 400, and in both Phase A and Phase B. The two lens types provided comparable logMAR visual acuity, and there was no significant differences in CS (Pelli Robson) between spectacle lens correction (equivalent spheres) and either lens type. The incidence of corneal epithelial staining was significantly higher and more severe with ActiFresh 400 than with ActiSoft 60, both in Phase A and Phase B. Statistically, there were no significant differences in the scores to the set of questions listed in the questionnaire between the two lens types, except for lens awareness and lens handling. Of the subjects having a preference for one lens, more subjects preferred ActiSoft 60 than ActiFresh 400. In terms of overall preference of the two lens types, at the end of Phase A, 50% of the subjects preferred ActiSoft 60 while only 30% preferred ActiFresh 400, the remaining 20% had no preference. However, by the end of Phase B, preferences for ActiSoft 60 and ActiFresh 400 were comparable. This appeared to be due mainly to the ease of lens handling of the latter.

Disposable contact lens use as a risk factor for microbial keratitis

AIMSA case-control study was performed to evaluate soft contact lens (SCL) wear modality as a risk factor for microbial keratitis.METHODSContact lens wearers presenting as new patients to Moorfields Eye Hospital...

Applications of Raman spectroscopy to ophthalmology: Spectroscopic characterization of disposable soft contact lenses

Disposable soft contact lenses based on HEMA-MAA hydrogels are examined using Raman and ATR/FTIR vibrational spectroscopies and thermal analysis. The main factors dealing with physical, chemical, and biological biocompatibility are evaluated in relation to those of long-wear soft contact lenses with the aim of individuating the most biocompatible lens. The Raman spectra of HEMA-MAA lenses show that some biocompatibility factors are affected by environmental conditions and, in particular, by changes in pH and ionic strength values.

Mesopic vision in myopia corrected by photorefractive keratectomy, soft contact lenses, and spectacles

Purpose: To evaluate contrast vision and glare sensitivity under mesopic conditions in eyes having uncomplicated excimer laser photorefractive keratectomy (PRK) for myopia and in eyes corrected by disposable soft contact lenses, soft contact lenses, and spectacles.Setting: Division of Experimental Ophthalmic Surgery, University of Tübingen, Germany.Methods: The Mesoptometer II test was used to evaluate mesopic vision (glare sensitivity and contrast vision) in 28 eyes of 14 patients wearing disposable soft contact lenses, 20 eyes of 10 patients wearing soft contact lenses, 39 eyes of 20 patients wearing spectacles, 30 eyes of 15 emmetropic patients, and 33 eyes of 22 patients after PRK with a 5.0 mm optical zone. Follow-up was between 15 and 60 months after PRK (mean 34.5 months).Results: The guidelines of the German Ophthalmologic Society state that patients must recognize Mesoptometer II contrast levels of 1:5 or better with and without glare to meet the minimum legal night-driving standards for private cars. All eyes with disposable soft contact lenses and soft contact lenses, all emmetropic eyes, and 38 eyes corrected by spectacles recognized contrast levels of 1:5 or better without glare. In contrast, 18 eyes in the PRK group were unable to recognize contrast level 1:5 without glare. With glare, 1 eye in the disposable soft contact lens group, 1 in the soft contact lens group, and 7 with spectacles were unable to recognize the 1:5 contrast level. All emmetropic eyes recognized contrast levels of 1:5 or better; 22 PRK eyes were unable to recognize contrast level 1:5 with glare.Conclusion: Myopic PRK may lead to long-term impairment of mesopic vision, while soft contact lens use does not seem to markedly influence mesopic vision in eyes with low to moderate myopia.

Comparative performance of disposable soft contact lenses

A short-term clinical study was undertaken to compare and evaluate the fit and clinical behaviour of eight disposable hydrogel contact lenses. Thirty subjects were enrolled in a 1-day, randomised, double-masked study. The lenses compared were Vistakon Acuvue (8.80), Vistakon Surevue (8.80), Aspect Frequency-55, Bausch & Lomb Medalist (SeeQuence 2), Ciba Focus (8.90), Lunelle Rythmic, Pilkington Barnes Hind Precision-Wand Wesley Jessen Freshlook. Three of the eight designs, Acuvue (86.7%), Precision-UV (86.7%) and Frequency-55 (90%), achieved relatively high levels of fitting success. The Rythmic lenses achieved the lowest success rate (70%) showing significantly greater downward decentration than the other designs. Although all the lenses were designed to fit a wide variety of eyes, they exhibited widely varying fitting characteristics. Some were more successful than others. The study shows that it is necessary for practitioners to utilise a range of lens designs in order to fit satisfactorily the typical contact lens population.

Changes to the ocular biota with time in extended- and daily-wear disposable contact lens use.

Gram-negative bacteria may play a role in the etiology of certain soft contact lens (SCL)-related diseases. Contact lens (CL) wear may modify the normal ocular biota, providing a more favorable environment for potential pathogens. This study reports temporal changes in ocular biota in daily-wear (DW) and extended-wear (EW) disposable SCL use in experienced and neophyte wearers. Lid margin and bulbar conjunctival biota were sampled prior to CL fitting in 26 previous DW SCL users, 18 previous EW SCL users, and 26 neophytes. Wearers were fitted with an etafilcon A CL in one eye and a polymacon CL in the fellow eye. Lenses were worn on a daily basis by the 26 previous DW SCL wearers and on an EW basis by the remaining 44 subjects. The ocular biota was further sampled after 1, 3, 6, 9, and 12 months of wear. The ocular biota consisted of coagulase-negative staphylococci, Corynebacterium spp., Micrococcus spp., and Propionibacterium spp. Potential pathogens were rarely isolated at baseline. No significant trend of increasing ocular colonization was shown for extended CL wear. Lid and conjunctival colonization increased with DW SCL use (P < 0.001), although this increase occurred for nonpathogenic species only. Fewer potential pathogens were isolated from DW SCL than from EW SCL users (P < 0.05). The lid margin consistently showed greater colonization than the conjunctiva and may be a source of potential pathogens during CL wear. Hydrogel CL wear appears to modify the ocular biota. An increased number of commensal organisms were present in DW SCL use. EW SCL use altered the spectrum of organisms isolated. These alterations may suppress the normal ocular defense mechanisms and may be relevant in the pathogenesis of CL-related disease.

The risk of microbial keratitis with daily-wear and extended-wear use of disposable lenses

Summary A pilot case-control study indicated an excess risk of microbial keratitis (MK) with disposable soft contact lenses (DSCL). A larger case-control study was conducted to separate the risks associated with daily-wear (DW) and extended-wear (EW) use of DSCL, and to determine whether there is an excess risk associated with the lenses after controlling for other variables. Contact lens (CL) wearers presenting as new patients to Moorfields Eye Hospital Casualty over 12 months completed a questionnaire detailing CL use and hygiene practices. Cases were patients with presumed MK, according to established clinical criteria. Controls were patients attending with disorders unrelated to CL wear. Relative risks were calculated using conventional soft lenses (SCL) as the referent, and multivariable analysis was performed. DW and EW patients were analysed separately. Among SCL wearers there were 89 cases, and 566 controls. Multivariable analysis confirmed a statistically significant increased risk with DSCL among both DW (×3.5) and EW patients (×4.8). This study shows that, despite the proven reduction in less serious complications with the disposable regimen, there is an increased risk of MK with both DW and EW DSCL, even after controlling for other variables. Although patient and practitioner factors may contribute to these risks, it is likely that properties of some DSCL are partly responsible and require further investigation.

The risk of microbial keratitis with daily‐wear and extended‐wear use of disposable lenses

SummaryA pilot case‐control study indicated an excess risk of microbial keratitis (MK) with disposable soft contact lenses (DSCL). A larger case‐control study was conducted to separate the risks associated with daily‐wear (DW) and extended‐wear (EW) use of DSCL, and to determine whether there is an excess risk associated with the lenses after controlling for other variables.Contact lens (CL) wearers presenting as new patients to Moorfields Eye Hospital Casualty over 12 months completed a questionnaire detailing CL use and hygiene practices. Cases were patients with presumed MK, according to established clinical criteria. Controls were patients attending with disorders unrelated to CL wear. Relative risks were calculated using conventional soft lenses (SCL) as the referent, and multivariable analysis was performed. DW and EW patients were analysed separately.Among SCL wearers there were 89 cases, and 566 controls. Multivariable analysis confirmed a statistically significant increased risk with DSCL among both DW (×3.5) and EW patients (×4.8).This study shows that, despite the proven reduction in less serious complications with the disposable regimen, there is an increased risk of MK with both DW and EW DSCL, even after controlling for other variables. Although patient and practitioner factors may contribute to these risks, it is likely that properties of some DSCL are partly responsible and require further investigation.