| trial frame | A type of spectacle frame with variable adjustments, for holding trial lenses during refraction. (05 Mar 2000) |
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| trial lenses | A series of cylindrical and spherical lens's used in testing vision. (05 Mar 2000) |
| trial of labour | Allowing a woman to be in labour long enough to determine if vaginal birth may be anticipated. (12 Dec 1998) |