Table 1. Studies describing the unadjusted annualised incidence of presumed microbial keratitis and vision loss in hydrogel contact lens wear, stratified by selection of controls (adapted from Stapleton et al78).
| First author | Total cases | Definition of microbial keratitis | Study design | Location | Incidence per 10 000 (95% CI). Daily wear | Incidence per 10 000 (95% CI). Extended wear |
|---|---|---|---|---|---|---|
| Denominator derived from random telephone survey of the community to identify penetrance of contact lens wearers. | ||||||
| Stapleton11 | 285 | Clinical diagnosis of microbial keratitis with either a positive corneal culture or infiltrate with overlying epithelial defect, with one or more of: lesion in the central cornea; anterior chamber response; and pain | 12-month prospective surveillance of practicing ophthalmologists and optometrists | Australia | 1.9 (1.8–2.0) Vision loss 0.4 (0.4–0.4) | 19.5 (14.6–29.5) Vision loss 4.0 (2.9–6.6) |
| Cheng9 | 92 | Clinical diagnosis of microbial keratitis in cosmetic contact lens wearers, excluding viral keratitis. Self-limiting small corneal lesions excluded | 3-month prospective surveillance of all practicing ophthalmologists | Netherlands | 3.5 (2.7–4.5) | 20.0 (10.3–35.0) |
| Seal74 | 27 | Presumed non-viral microbial keratitis | 8-month prospective, population surveillance via 8 hospitals | Western Scotland | 2.7 (1.6–3.7) | — |
| Poggio16 | 195 | Corneal stromal infiltrate with an overlying epithelial abnormality (ulceration) clinically diagnosed as microbial keratitis, received antibiotic treatment | 4-month prospective surveillance of all practicing ophthalmologists | Five states in northern United States | 4.1 (2.9–5.2) | 20.9 (15.1–26.7) |
| Denominator derived from fitting surveys. CL type and modality by matched controls | ||||||
| Morgan75 | 38 | Prospective identification of corneal infiltrative events associated with CL wear. ‘Severe' keratitis defined as cases with clinical severity score >8/22 National fitting data applied to estimated hospital catchment population | 12-month prospective study of patients presenting to hospital accident and emergency clinic | Royal Eye Hospital, Manchester, UK | 6.9 (6.3–7.5) | 96.4 (37.5–245.2) |
| Lam10 | 59 | Clinical diagnosis, corneal stromal infiltrate >1 mm2 usually but not necessarily with an overlying epithelial defect, excluding inflammatory, herpetic and adenoviral keratitis. Retrospective fitting survey data (1994) applied to 1998 census data | 17-month prospective survey of two hospitals and 27 private ophthalmologists | Hong Kong | 3.1 (2.1–4.0) | 9.3 (4.9–13.7) |
| Denominator derived from practitioner fitting surveys | ||||||
| Nilsson76 | 26 | CL induced keratitis, defined as full epithelial defect with a stromal infiltrate or full ulcer. | 3-month prospective national surveillance of all ophthalmologists | Sweden | 2.2 (0.4–3.9) Vision loss 0.5 (0.3–0.8) | 13.3 (4.1–22.6) |
Abbreviations: CI, confidence interval; CL, contact lens.