Clinical and Experimental Ophthalmology 2004; 32: 349–353 Clinical Technique _________________________________ Clinical Technique Evaluation of surveillance methods for an epidemiological study of contact lens related microbial keratitis Lisa Keay BOptom, 1,2 Katie Edwards BAppSci(Optom), 1,2 Garry Brian FRANZCO, 3 Thomas Naduvilath PhD 1,2 and Fiona Stapleton PhD 1,2 1 Cornea and Contact Lens Research Unit, School of Optometry and Vision Science, 2 Vision Cooperative Research Centre, and 3 International Centre for Eyecare Education, University of New South Wales, Sydney, New South Wales, Australia ABSTRACT Purpose: To evaluate surveillance methods in a pilot epide- miological study of contact lens related microbial keratitis (MK) cases identified by ophthalmic practitioners in Aus- tralia and New Zealand between May and August 2003 inclusive. Methods: Twelve ophthalmologists and 55 optometrists from rural and metropolitan locations were sent a study information pack with postal reporting forms. After 2 months, practitioners were emailed a link to a website for Internet reporting. After 4 months, practitioners were prompted by email and then by telephone if a response was not received. Passive response rates were the rate of returns after posting information and emailing the website link. Active response rates included personalized email and telephone follow-up. Results: Ten cases of MK were identified by optometrists and five by ophthalmologists. The passive response rates were 79% and 58% for the first and second reporting periods, respectively. There was a lower response rate in the second reporting period compared to the first (P = 0.02). With active surveillance the response rate increased to 97% and 96%. A large proportion of optome- trists (62%) and ophthalmologists (55%) used the website for at least one reporting period. Internet reporting was used by all New Zealand practitioners (5/5). Conclusions: A surveillance study to estimate the inci- dence of contact lens related MK in Australia and New Zealand is feasible and acceptable. Internet-based reporting offers a reliable, rapid and cost-effective means of running a large scale, international surveillance study. Active surveil- lance methods are necessary to enhance reporting rates. Key words: corneal ulceration, Internet, microbial keratitis, response rate, surveillance. INTRODUCTION Microbial keratitis (MK) is a rare but debilitating complica- tion of contact lens wear and many studies have shown increased risk with overnight contact lens use. 1–6 Estimates of the incidence of MK with daily and extended wear of soft contact lenses have proven to be remarkably consistent across time. 2,3 It is widely agreed that surveillance tech- niques are best suited to estimating the incidence of rare disease where cohorts would otherwise be large and poten- tially unmanageable. 7,8 Silicone hydrogel contact lenses were first licensed for 30 nights continuous wear in Australia and New Zealand in 1999 and now have significant market penetration in both countries. 9 Although premarket clinical trials 10–12 and phys- iological studies 13,14 demonstrate that hypoxia has been eliminated with silicone hydrogel lenses, it is not known whether this will result in a protective effect against the risks or severity of MK. There are now published case reports of MK with silicone hydrogel contact lenses. 15–17 It is therefore timely to examine for the first time the incidence rates with these new contact lens materials and wear modalities. Internet reporting has not been utilized as a means of gathering data from practitioners in Australian ophthalmo- logical surveillance studies 18 or the many previously reported studies of contact lens related MK. 2,3,5,19–21 The US federal agency for the Center for Disease Control and Prevention (CDC) advocates the future national standardization of public health surveillance systems with the electronic handling of data in the interests of speed and efficiency in managing large volumes of data. 22 The present study exam- ines for the first time use of Internet-based surveillance methods in Australian and New Zealand eye care. ■ Correspondence: Ms Lisa Keay, CCLRU, Level 5, Rupert Myers Building, Gate 14 Barker Street, University of NSW, Sydney, NSW 2052, Australia. Email: l.keay@visioncrc.org Presented at the 2003 Australasian Ophthalmic and Visual Sciences Meeting, Melbourne, Australia, 29–30 November 2003.