Characteristics of soft contact lenses (SCL) wearers studied for risk of microbial keratitis (MK). (Values are numbers (percentages) unless stated otherwise)
| MK cases (n=89) | Controls (n=566) | |
|---|---|---|
| Mean age (range) | 28.3 (13–55) | 30.8 (14–71) |
| Ratio of males to females | 43 (48) | 209 (37) |
| Social class based on occupation: | ||
| I-II | 51 (57) | 345 (61) |
| III-V | 38 (43) | 221 (39) |
| Experience of contact lens wear: | ||
| 0–5 years | 57 (64) | 315 (56) |
| >5 years | 32 (36) | 251 (44) |
| Previous use of an alternative contact lens type: | ||
| No | 44 (49) | 345 (61) |
| Yes | 45 (51) | 221 (39) |
| Soft contact lens type: | ||
| Daily wear (DW) non-disposable | 34 (38) | 426 (75) |
| DW disposable: | 23 (26) | 86 (15) |
| Acuvue (Vistakon) | 20 (23) | 58 (10) |
| Other | 3 (3) | 28 (5) |
| Extended wear (EW) non-disposable: | 8 (9) | 28 (5) |
| EW disposable: | 24 (27) | 26 (5) |
| Acuvue (Vistakon) | 21 (24) | 24 (4) |
| Other | 3 (3) | 2 (1) |
| Unscheduled overnight use among DW patients: | ||
| No | 43 (75) | 464 (91) |
| Yes (< once per week) | 14 (25) | 48 (9) |
| Extent of overnight use among EW patients: | ||
| Mean nights in a row | 9.6 | 13.1 |
| SCL disinfection: | ||
| Chlorine release systems | 24 (27) | 114 (20) |
| Hydrogen peroxide | 27 (30) | 283 (50) |
| Other chemical | 8 (9) | 117 (21) |
| None | 15 (17) | 37 (6) |
| Disposal on removal | 15 (17) | 15 (3) |