Evaluation of surveillance methods for an epidemiological study of contact lens related microbial keratitis.
OBJECTIVE
To evaluate surveillance methods in a pilot epidemiological study of contact lens related microbial keratitis (MK) cases identified by ophthalmic practitioners in Australia 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 optometrists (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 incidence 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 surveillance methods are necessary to enhance reporting rates.
Cornea and Contact Lens Research Unit, School of Optometry and Vision Science, University of New South Wales, Sydney, New South Wales, Australia. l.keay@visioncrc.org
Lisa
L
Keay
Katie
K
Edwards
Garry
G
Brian
Thomas
T
Naduvilath
Fiona
F
Stapleton
D000293:Adolescent; D000328:Adult; D001315:Australia / Q000453:epidemiology; D003261:Contact Lenses / Q000009:adverse effects* / Q000706:statistics & numerical data; D003320:Corneal Ulcer / Q000453:epidemiology* / Q000382:microbiology; D004812:Epidemiologic Methods; D015818:Eye Infections, Bacterial / Q000453:epidemiology* / Q000209:etiology; D006801:Humans; D015994:Incidence; D020407:Internet; D008875:Middle Aged; D009520:New Zealand / Q000453:epidemiology; D009885:Ophthalmology / Q000706:statistics & numerical data; D009907:Optometry / Q000706:statistics & numerical data; D010865:Pilot Projects; D011159:Population Surveillance / Q000379:methods*; D012423:Rural Health / Q000706:statistics & numerical data; D014504:Urban Health / Q000706:statistics & numerical data