The risk of transmission of variant Creutzfeldt–Jakob disease via contact lenses and ophthalmic devices

Technical Report: Guidelines for Handling of Multipatient Contact Lenses in the Clinical Setting

SIGNIFICANCE

Standardized guidelines that are clinically practical are needed to assist the prescriber in minimizing the risk of conveying infection through multiuse diagnostic contact lens use and reuse.Contact lens prescribers face the specter of transferring potential pathogens from one patient to another when reusing diagnostic (trial) contact lenses on multiple patients because infectious organisms have been recovered from worn contact lenses, although there is no evidence of transmission through this mechanism. These pathogens can be introduced into the system from one patient to another, or they may be introduced by clinician lens handling, storage, or both. These pathogens can cause acute or chronic systemic or ocular infection that can lead to significant morbidity (temporary or permanent) that includes vision loss.

Homogenous photocatalytic decontamination of prion infected stainless steel and titanium surfaces

Prions are notorious for their extraordinary resistance to traditional methods of decontamination, rendering their transmission a public health risk. Iatrogenic Creutzfeldt-Jakob disease (iCJD) via contaminated surgical instruments and medical devices has been verified both experimentally and clinically. Standard methods for prion inactivation by sodium hydroxide or sodium hypochlorite have failed, in some cases, to fully remove prion infectivity, while they are often impractical for routine applications. Prion accumulation in peripheral tissues and indications of human-to-human bloodborne prion transmission, highlight the need for novel, efficient, yet user-friendly methods of prion inactivation. Here we show both in vitro and in vivo that homogenous photocatalytic oxidation, mediated by the photo-Fenton reagent, has the potential to inactivate the pathological prion isoform adsorbed on metal substrates. Photocatalytic oxidation with 224 μg mL(-1) Fe (3+), 500 μg mL(-1) h(-1) H 2O 2, UV-A for 480 min lead to 100% survival in golden Syrian hamsters after intracranial implantation of stainless steel wires infected with the 263K prion strain. Interestingly, photocatalytic treatment of 263K infected titanium wires, under the same experimental conditions, prolonged the survival interval significantly, but failed to eliminate infectivity, a result that we correlate with the increased adsorption of PrP(Sc) on titanium, in comparison to stainless steel. Our findings strongly indicate that our, user--and environmentally--friendly protocol can be safely applied to the decontamination of prion infected stainless steel surfaces.

Clinical performance of an orthokeratology lens fitted with the aid of a computer software in Chinese children

PURPOSE

To report the clinical performance of the orthokeratology (ortho-k) lens fitted with computer assisted system after 1-month of lens wear, in a group of children undergoing ortho-k treatment in a 2-year randomized myopic control study.

METHOD

Children aged 6-11 years old were fitted with the ortho-k lenses using computerized fitting. The initial myopia was 4.00-0.50 D and the initial refractive astigmatism was within 1.25 D. Lens performance, in terms of centration, myopic reduction, vision, ocular health status and lens binding incidence, was evaluated at one night, one week and one month after lens wear. Only data from the right eye was presented.

RESULTS

The initial spherical equivalent refraction (SER) for the 51 subjects was -2.29 ± 0.81 D. The first fit success rate was 90%. The reduction of SER after one night and one week aftercare visit were 57% and 81%, respectively. At the one month visit, the mean reduction in SER was 89% with unaided logMAR visual acuity of 0.03 ± 0.11. Mild central corneal staining was found in 9-20% of the subjects at the aftercare visits. The incidences of lens binding at one night, one week and one month aftercare visits were 17%, 39% and 30%, respectively.

CONCLUSIONS

Computer assisted system for Menicon Z Night lens fitting gave a high first fit success rate. Menicon Z Night lens was effective in myopic reduction and provided stable vision after one week of lens wear. Ocular health of the subjects after lens wear was generally unremarkable.

A comparison of clinical performance between disposable and Goldmann tonometers

PURPOSE

Applanation tonometry as performed in routine clinical practice is a significant potential vehicle for cross-infection particularly in an emergency eye care setting. The aim of this study is to evaluate the accuracy and reliability of three single-use devices (Tonoshield, Tonosafe, Tonojet) as an alternative to standard Goldmann prisms in an emergency eye department.

METHODS

All patients attending the eye casualty at the Manchester Royal Eye Hospital for a period of 4 months who required intraocular pressure measurement were eligible for this prospective study. Exclusion criteria were: age below 18 years, corneal anomalies that might affect measurement, and refusal to participate. After taking informed consent, the patient was examined by one experienced nurse practitioner, who measured the intraocular pressure three times. In the first part of the study, we compared the standard Goldmann prism vsTonoshield and Tonosafe prisms, while for the second part of the study we used standard Goldmann, Tonosafe, and Tonojet prisms. Agreement and repeatability tests were carried out on separate samples.

RESULTS

Tonosafe and Tonojet correlated well with standard Goldmann tonometry (P<0.001), while the measurements obtained with Tonoshield were higher, especially for raised intraocular pressure measurements. Tonojet and Tonosafe measurements were more reproducible than Tonoshield measurements.

CONCLUSIONS

This study shows that Tonosafe and Tonojet are accurate and reliable alternatives to standard Goldmann tonometry.