Sir,

We read with interest the clinical study by Leslie et al,1 in the May (2003) issue of Eye. The authors eloquently showed the contamination results before and after the use of an automated rinsing system. They hypothesized that the contamination may be the cause of endophthalmitis found in their unit, but another observation can be made from their results. The contaminants noted by the authors included organisms, lens capsule and cells. The question of whether these organisms were viable or not is certainly significant but the finding of lens material may pose a risk of transmission of Creutzfeldt–Jakob disease (CJD).

CJD is a transmissible human spongioform encephalopathy characterized by the presence of abnormal prion protein. Different forms of the disease exists, for example, sCJD (sporadic), iCJD (following iatrogenic spread), fCJD (familial), and vCJD (variant, following the consumption of infected beef). Several authors have commented on CJD transmission from ocular transplants, for example, cornea2 or sclera.3 However, intraocular surgical transmission is of concern due to the sheer volume of cataract surgery performed. Hogan et al showed a 10-fold increase in prion titres in the lens in scrapie-infected hamsters once they had become neurologically symptomatic. In fact, levels in the lens were similar to levels in the cornea prior to the onset of neurological symptoms but became significantly higher than those in the cornea after the onset of symptoms, retina having the highest titres.4 Intraocular ‘inoculation’ by phacoemulsification and irrigation-aspiration handpieces contaminated by lens material certainly would provide a route for transmission.

The recent steps taken by the Department of Health in reviewing sterilizing units probably triggered by the outbreak of vCJD is certainly welcomed.5 The risk of intraocular transmission in anterior segment surgery is probably greater from sCJD than vCJD due to the age of the patients affected by the respective conditions. Tissue distribution of prion protein from human eyes has as yet to show levels of prion in the cornea or lens,6, 7 but the authors concluded that the inability to detect prion protein in the cornea or lens could not be taken as evidence for the absence of infectivity in these tissues.7

Since prions adhere strongly to metal surfaces and are resistant to many sterilization processes,8 the reduction of contaminants as illustrated by this report in patients with known or suspected CJD9 and the use of single-use equipment5 (eg disposable simcoe) will reduce risks of transmission further.