RGP Edges: Can Practitioners Assume The Labs Are compliant? A Case For In-Office Modification.

Thirty-six RGP lenses were examined with a modified radiuscope edge analyzer to determine whether or not they needed modification. The sample was made up of four trial sets: Envision 9.6, Fluorocon 9.5, Regional Silicone-acrylate 9.5, and a Regional Silicone-acrylate 9.0. The lenses were evaluated by a pass/modify criteria based on the clinical relevance of apex position, front taper, and edge uniformity. This study showed that 83% of the lenses examined needed modification. In addition, 22% of the lenses failed in every criteria. Lack of anterior taper, resulting in thick lenses, was the single most consistent flaw found among the test sample. The pass rate (6/36) was so low in this study that comparisons between materials and/or different overall diameters from the same lab
are inconclusive at best. A good edge appears to be almost a random phenomenon. This study is contrasted with Andrasko's study (74% of lab edges are acceptable) to show how different definitions can bring significantly different conclusions about edge quality. Finally, a strong case is made for routine in-office modification.