Cherry Radford

Acanthamoeba keratitis in England and Wales: incidence, outcome, and risk factors

AUTHOR:e-mail address please Aim: To determine the incidence, regional variation in frequency, outcome, and risk factors for acanthamoeba keratitis (AK) in England and Wales. Methods: AK cases presenting from 1 October 1997 to 30 September 1999 were identified by the British Ophthalmic Surveillance Unit active reporting system. Clinical and patient postal questionnaire data were analysed. Results: 106 reported cases met study criteria. The annual incidence for the 2 years was 1.26 and 1.13 per million adults and, for contact lens (CL) wearers, 21.14 and 17.53 per million. There was marked regional variation in incidence (0 to 85.13 per million adult CL wearers), with CL wearers in the south having a ninefold increased risk of AK compared with those resident in the north (95% confidence limits: 2.2–38.9, p<0.0001), and a threefold increased risk with hard as opposed to soft domestic water (95% confidence limits: 1.73 to 6.58, p<0.001). Treatment and outcome data were similar to those previously reported. 93/106 (88%) patients were CL wearers. Among these, 46/77 (60%) were disinfecting irregularly, and 20/63 (32%) had been swimming in CLs. One step hydrogen peroxide and chlorine release soft CL (SCL) disinfection systems were significantly over-represented among the cases. Among SCL users, one or more previously established risk factors for AK were identified in 50/55 (91%) patients. Conclusions: The incidence was considerably higher than most previous estimates, and was static. The geographical variation in incidence may be partly related to the increase in risk associated with hard water. The fact that water quality can have such an effect on the risk of AK suggests that many CL wearers must be letting tapwater come into contact with their lenses or storage cases. Improved education for CL wearers and practitioners about hygiene practice and the variable efficacy of contact lens systems could be expected to reduce the incidence of this disease.

Risk Factors for Microbial Keratitis with Contemporary Contact Lenses : A Case-Control Study

OBJECTIVE To assess the relative risks (RR) of microbial keratitis (MK) for contemporary contact lens (CL) types and wearing schedules. DESIGN A 2-year prospective case-control study begun in December 2003. PARTICIPANTS Cases were 367 CL wearers attending Moorfields Eye Hospital with proven or presumed MK. Controls were 1069 hospital controls, who were CL wearers with a disorder unrelated to CL wear, and 639 population-based controls who were CL wearers randomly selected from the Moorfields catchment area. Hospital patients completed a self-administered questionnaire; population-based controls were interviewed by telephone. TESTING Multivariate analysis was done both for all cases of MK, and for the moderate and severe MK subgroups alone. MAIN OUTCOME MEASURES The RR for developing MK, and vision loss, for all lens types compared with planned replacement soft lenses (the referent). RESULTS Compared with planned replacement soft lenses (the referent), the RR of MK was significantly increased with daily disposable (DD) CLs (RR, 1.56x [95% confidence interval (CI), 1.1-2.1]; P = 0.009) and differed between different brands of DD lens, was reduced for rigid lenses (RR, 0.16x [95% CI, 0.06-0.4]; P<0.001), and no different for silicone hydrogel or other types of soft lens. Although the risk of MK was higher overall among DD lens users, the risk of vision loss was less than for planned replacement soft CL users (P = 0.05); no DD lens users lost vision to the level of >or=20/40. The RR for overnight wear, for any lens type, was 5.4 times higher (95% CI, 3.3-10.9; P<0.001). Comparison of the DD soft CL types with planned replacement soft lenses (the referent), showed significant differences between brands for the risk of MK. CONCLUSIONS The risk of MK has not been reduced in users of DD and silicone hydrogel CLs. However, vision loss is less likely to occur in DD than in reusable soft CL users. Different brands of CL may be associated with significantly different risks of keratitis; understanding these differences should lead to the development of safer soft lenses. These findings suggest that lens/ocular surface interactions may be more important in the development of corneal infection than oxygen levels and CL case contamination.

Acanthamoeba keratitis: multicentre survey in England 1992–6

AIM To investigate the frequency, outcomes, and risk factors for acanthamoeba keratitis (AK) in England during the past 4 years. METHODS An ophthalmologist in 12 of the 14 regional health authorities (RHAs) coordinated identification of patients in their region presenting with AK between 1 October 1992 and 30 September 1996. Clinical and postal patient questionnaire data were analysed. RESULTS 243 patients (259 eyes) with an AK diagnosis were identified, equating to an annualised incidence of 0.14 per 100 000 individuals. UK resident patients for each year numbered 50, 71, 73, and 32 respectively. Among patients with sufficient data 170/237 (72%) were diagnosed early (within 30 days of presentation), 197/218 (90%) were treated with polyhexamethyl biguanide and/or chlorhexidine, and 40/243 (16%) underwent surgery. Visual acuities of 6/12 or better were achieved by 222/259 (86%) eyes, including 84 eyes of patients under review or lost to follow up. Non-contact lens (CL) wearers were associated with delayed diagnosis, increased need for surgery and a poorer visual outcome (only 10/18 eyes, 56%, achieved 6/12 acuity). 225/243 (93%) patients were CL wearers, and 205/243 (84%) were soft CL (SCL) users. Among SCL user respondents, previously identified risk factors—swimming with CL (47/138, 34%), non-sterile CL rinsing (11/138, 8%), omitted disinfection (85/138, 62%), and chlorine release disinfection (65/138, 47%)—were identified for 125/138 (91%) patients. CONCLUSIONS Earlier diagnosis and more effective medical therapy have improved the prognosis for most AK patients. The study demonstrates the highly preventable nature of the disease: 91% of the SCL wearers could have avoided the disease by refraining from inadvisable practices, and a marked fall in frequency was seen after intensive media attention to AK, possibly in conjunction with increasing penetrance of new CL products. Since the frequency of AK appears to be largely determined by the ever changing trends in CL use, continued monitoring is indicated.

Risk factors for Acanthamoeba keratitis in contact lens users : A case control study

Abstract Objective: To investigate reasons for an increase in cases of Acanthamoeba keratitis related to contact lenses. Design: Case-control study. Cases were contact lens related acanthamoeba keratitis patients treated between 1 September 1989 and 31 August 1992. Controls were lens users without lens related disease who presented as new patients to the casualty department from 1 March 1992 to 31 August 1992. All subjects completed a questionnaire detailing lens use and hygiene practices. Setting: Eye hospital. Subjects: 35 cases with acanthamoeba keratitis and 378 controls. Main outcome measures: Relative risks comparing different contact lens types, socioeconomic classification, age, sex, lens use, lens wearing experience, hygiene compliance, and hygiene systems. Results: The crude relative risk for developing acanthamoeba keratitis with the use of daily wear disposable lenses was 49.45 (95% confidence interval 6.53 to 2227; P<0.001) compared with conventional soft lenses (the referent). Multivariable analysis showed that this increased risk could be largely attributed to lack of disinfection (relative risk 55.86 (10 to 302); P<0.001) and use of chlorine based disinfection (14.63 (2.8 to 76); P=0.001) compared with other chemical systems (the referent). None of the other outcome measures showed a significant association. Conclusions: Both failure to disinfect daily wear soft contact lenses and the use of chlorine release lens disinfection systems, which have little protective effect against the organism, are major risk factors for acanthamoeba keratitis. These risks have been particularly common in disposable lens use. Over 80% of acanthamoeba keratitis could be avoided by the use of lens disinfection systems that are effective against the organism. Key messages Key messages These risk factors are both more common in users of disposable daily wear soft lenses Over 80% of acanthamoeba infections could be eliminated by daily disinfection of reused lenses with systems effective against the organism Disinfection systems ineffective against acanthamoeba should not be licenced for use

Risk factors for nonulcerative contact lens complications in an ophthalmic accident and emergency department: a case-control study.

PURPOSE To assess the relative risks of acute, nonulcerative complications with recently introduced contact lens (CL) wear modalities (compared with the previously most common soft lens wear schedule), and to identify any other associated factors. DESIGN A 2-year prospective case-control study commencing in December 2003. PARTICIPANTS Cases were 877 CL wearers attending Moorfields Eye Hospital with CL-related disorders other than microbial keratitis. Controls were 1069 hospital controls who were CL wearers presenting with a disorder unrelated to CL wear, and 639 population-based controls who were CL wearers randomly selected from the Moorfields catchment area. Hospital patients completed a self-administered questionnaire; population controls were interviewed by telephone. TESTING The relative risks of developing the CL-related disorders with different CL types were evaluated. For the more common disorders, multivariable analysis was undertaken. MAIN OUTCOME MEASURES The relative risk of developing an acute, nonulcerative, CL-related disorder. RESULTS Compared with planned replacement soft CL, daily disposable lenses significantly reduced the risk of toxic/hypersensitivity (odds ratios for CL solution disorders and papillary conjunctivitis 0.1 and 0.5; P<0.001 and P = 0.05, respectively) and metabolic disorders (0.4; P=0.04), but the most commonly used brand was associated with increased risks of sterile keratitis (2.7x; 95% confidence interval [CI], 1.7-4.1; P<0.001), mechanical disorders (2.2x; 95% CI, 1.5-3.2; P<0.001), and a tendency for patients to have lens removal difficulties (P<0.001). Silicone hydrogel CL wear was free from hypoxic complications but associated with an increased risk of sterile keratitis (2.0x; 95% CI, 1.2-3.3; P=0.005), mechanical disorders (1.8x; 95% CI, 1.1-2.8; P=0.015), and attendance with any nonulcerative complication (1.9x; 95% CI, 1.5-2.6; P<0.001) when compared with other reusable soft lenses. Significant additional risk factors were identified for sterile keratitis (overnight wear [ON], more days per week of lens wear, poor hand hygiene, smoking, and less CL experience) and mechanical disorders (ON and less CL experience). CONCLUSIONS Neither of the 2 recently introduced CL modalities-daily disposable and silicone hydrogel lenses-reduced the overall risk of acute nonulcerative disorders.

DISPOSABLE CONTACT LENS USE AS A RISK FACTOR FOR MICROBIAL KERATITIS

AIMS A case-control study was performed to evaluate soft contact lens (SCL) wear modality as a risk factor for microbial keratitis. METHODS Contact lens wearers presenting as new patients to Moorfields Eye Hospital accident and emergency department during a 12 month period completed a self administered questionnaire detailing demographic data and contact lens use habits. Cases were patients with a clinical diagnosis of SCL related microbial keratitis. Controls were SCL users attending with disorders unrelated to contact lens wear. Odds ratios (estimates of relative risks) and 95% confidence limits (CL) were calculated through multivariable logistic regression analysis. RESULTS There were 89 cases and 566 controls. A substantially increased risk with 1–4 weekly disposable SCL compared with non-disposable SCL was identified among both daily wear (DW) (odds ratio =3.51, 95% CL 1.60–7.66, p=0.002) and extended wear (odds ratio 4.76, 95% CL 1.52–14.87, p=0.007) users after adjustment for demographic, lens use and hygiene variables. Other significant factors among DW users were “occasional” overnight use, use of chlorine based (as opposed to other chemical) systems in combination with poor storage case hygiene, and irregular disinfection. CONCLUSION Properties of some disposable SCL may be partly responsible for these excess risks. It is also possible, however, that this finding is largely a reflection of widespread complacency among patients and practitioners with respect to disposable SCL fitting and use.

Contact lens hygiene compliance in a universitypopulation

Abstract Hygiene practices of 207 contact lens wearers in a university population were surveyed using a self-administeredquestionnaire. Participants were then interviewed to clarify their responses; 178 subjects were asymptomatic. Individual hygiene standards were quantified with a weighted scoring system. Three months later, 48 of the least compliant subjects were reassessed. Of the 178 asymptomatic subjects, 23 (13%) were compliant, while a further 57 (32%) maintained reasonable standards. Inattention to lens case cleaning was the most common failing (128/178, 72%). Compliance was strongly associated with the length of contact lens experience (p

Incidence, presenting features, and diagnosis of cicatrising conjunctivitis in the United Kingdom.

PurposeCicatrising conjunctival disorders are uncommon, and are difficult to diagnose and manage. This study was designed to assess the annual incidence and underlying diagnosis of patients with cicatrising conjunctivitis (CC) within the United Kingdom.MethodsClinical data of newly diagnosed cases of CC were reported via the British Ophthalmological Surveillance Unit at diagnosis and at 12 months follow-up.ResultsA total of 50 (61%) ocular mucous membrane pemphigoid (OcMMP), 16 (20%) Stevens–Johnson syndrome/toxic epidermal necrolysis (SJS-TEN) and 16 (20%) other causes of CC, equating to an incidence of 0.8, 0.2, and 0.2 per million, respectively, were reported. Although diagnosis of SJS-TEN was usually within a median of 7 days of symptom-onset, that for OcMMP and other CC was a median 225 days for both. At diagnosis, 64/163 (39%) eyes had moderate/severe conjunctival inflammation, and 102/164 (62%) had symblepharon formation. Although 43/82 (52%) patients were commenced on immunosuppression or had this therapy modified, at follow-up there was an increase in the number of symblepharon, despite control of inflammation (P<0.001). Mortality only occurred in the SJS-TEN group (4/16 (25%)).ConclusionCC has a substantial morbidity and for non-SJS-TEN causes, diagnosis is frequently delayed. The proportion of patients given immunosuppressive therapy to prevent disease progression may be less than optimal. These data highlight the need for developing patient access to specialist-designated centres with expertise in CC.

Evaluation of early and late presentation of patients with ocular mucous membrane pemphigoid to two major tertiary referral hospitals in the United Kingdom

PurposeOcular mucous membrane pemphigoid (OcMMP) is a sight-threatening autoimmune disease in which referral to specialists units for further management is a common practise. This study aims to describe referral patterns, disease phenotype and management strategies in patients who present with either early or established disease to two large tertiary care hospitals in the United Kingdom.Patients and MethodsIn all, 54 consecutive patients with a documented history of OcMMP were followed for 24 months. Two groups were defined: (i) early-onset disease (EOD:<3years, n=26, 51 eyes) and (ii) established disease (EstD:>5years, n=24, 48 eyes). Data were captured at first clinic visit, and at 12 and 24 months follow-up. Information regarding duration, activity and stage of disease, visual acuity (VA), therapeutic strategies and clinical outcome were analysed.ResultsPatients with EOD were younger and had more severe conjunctival inflammation (76% of inflamed eyes) than the EstD group, who had poorer VA (26.7%=VA<3/60, P<0.01) and more advanced disease. Although 40% of patients were on existing immunosuppression, 48% required initiation or switch to more potent immunotherapy. In all, 28% (14) were referred back to the originating hospitals for continued care. Although inflammation had resolved in 78% (60/77) at 12 months, persistence of inflammation and progression did not differ between the two phenotypes. Importantly, 42% demonstrated disease progression in the absence of clinically detectable inflammation.ConclusionsThese data highlight that irrespective of OcMMP phenotype, initiation or escalation of potent immunosuppression is required at tertiary hospitals. Moreover, the conjunctival scarring progresses even when the eye remains clinically quiescent. Early referral to tertiary centres is recommended to optimise immunosuppression and limit long-term ocular damage.

Risk factors and causative organisms in microbial keratitis in daily disposable contact lens wear

Purpose This study investigated independent risk factors and causative organisms in microbial keratitis in daily disposable contact lens (CL)-wearers. Methods A multisite prospective case-control study was undertaken. Cases were daily disposable CL-wearers attending Moorfields Eye Hospital with microbial keratitis and those reported through a one-year surveillance study in Australia and in New Zealand. A population-based telephone survey identified daily disposable CL-wearing controls. Subjects completed a questionnaire describing CL-wear history, hygiene and demographics. The sample used for risk factor analysis was weighted in proportion to the CL-wearing population at each location. Corneal scrape results were accessed. Independent risk factors were determined using multiple binary logistic regression. Causative organisms in different CL-wear modalities were compared using a chi-squared test. Results 963 daily disposable CL-wearers were identified, from which 67 cases and 374 controls were sampled. Independent risk factors were; wearing CLs every day compared with less frequent use (OR 10.4x; 95% CI 2.9–56.4), any overnight wear (OR 1.8x; 95% CI 1.6–2.1), less frequent hand washing (OR 1.8x; 95% CI 1.6–2.0), and smoking (OR 1.3x; 95% CI 1.1–1.6). Certain daily disposable CLs (OR 0.2x; 95% CI 0.1–0.2) had protective effects. Environmental organisms were less frequently recovered with daily disposable CLs (20%), compared with other modalities (36%; p<0.02). Conclusion Overnight wear, increased exposure in daily wear, smoking and poor hand hygiene are significant risk factors for microbial keratitis with daily disposable CLs. Risk varied with daily disposable CL type. The profile of causative organisms is consistent with less severe disease.