Radius and Vertex Conversions in Eye Care
Radius and Vertex Conversions for Optometry
In the practice of optometry, precise measurements are essential for accurate lens fitting and vision correction. Two critical aspects of these measurements are radius and vertex conversions, which play a vital role in determining the curvature of contact lenses and the effective power of spectacle lenses, respectively. The following tables provide a comprehensive guide for optometrists and eye care professionals to easily convert between radius and vertex measurements, ensuring precise calculations for optimal patient outcomes. The first table focuses on radius conversions, offering a quick reference for converting between diopters and millimeters. The second table is dedicated to vertex conversions, facilitating the accurate calculation of lens power adjustments based on the Spectacle Rx.
Radius Conversions
| Diopters | mm |
|---|---|
| 36.00 | 9.38 |
| 36.25 | 9.31 |
| 36.50 | 9.25 |
| 36.75 | 9.18 |
| 37.00 | 9.12 |
| 37.25 | 9.06 |
| 37.50 | 9.00 |
| 37.75 | 8.94 |
| 38.00 | 8.88 |
| 38.25 | 8.82 |
| 38.50 | 8.77 |
| 38.75 | 8.71 |
| 39.00 | 8.65 |
| 39.25 | 8.60 |
| 39.50 | 8.54 |
| 39.75 | 8.49 |
| 40.00 | 8.44 |
| 40.25 | 8.39 |
| 40.50 | 8.33 |
| 40.75 | 8.28 |
| 41.00 | 8.23 |
| 41.25 | 8.18 |
| 41.50 | 8.13 |
| 41.75 | 8.08 |
| 42.00 | 8.04 |
| 42.25 | 7.99 |
| 42.50 | 7.94 |
| 42.75 | 7.89 |
| 43.00 | 7.85 |
| 43.25 | 7.80 |
| 43.50 | 7.76 |
| 43.75 | 7.71 |
| 44.00 | 7.67 |
| 44.25 | 7.63 |
| 44.50 | 7.58 |
| 44.75 | 7.54 |
| 45.00 | 7.50 |
| 45.25 | 7.46 |
| 45.50 | 7.42 |
| 45.75 | 7.38 |
| 46.00 | 7.34 |
| 46.25 | 7.30 |
| 46.50 | 7.26 |
| 46.75 | 7.22 |
| 47.00 | 7.18 |
| 47.25 | 7.14 |
| 47.50 | 7.10 |
| 47.75 | 7.07 |
| 48.00 | 7.03 |
| 48.25 | 6.99 |
| 48.50 | 6.96 |
| 48.75 | 6.92 |
| 49.00 | 6.88 |
| 49.25 | 6.85 |
| 49.50 | 6.81 |
| 49.75 | 6.78 |
| 50.00 | 6.74 |
| 50.25 | 6.72 |
| 50.50 | 6.68 |
| 50.75 | 6.65 |
| 51.00 | 6.62 |
| 51.25 | 6.59 |
| 51.50 | 6.55 |
| 51.75 | 6.52 |
| 52.00 | 6.49 |
| 52.25 | 6.46 |
| 52.50 | 6.43 |
| 52.75 | 6.40 |
| 53.00 | 6.37 |
| 53.25 | 6.34 |
| 53.50 | 6.31 |
| 53.75 | 6.28 |
Vertex Conversions
| Minus (-) | SRx | Plus (+) |
|---|---|---|
| -3.87 | 4.00 | 4.25 |
| -4.00 | 4.25 | 4.50 |
| -4.25 | 4.50 | 4.75 |
| -4.50 | 4.75 | 5.00 |
| -4.75 | 5.00 | 5.25 |
| -5.00 | 5.25 | 5.62 |
| -5.12 | 5.50 | 5.87 |
| -5.37 | 5.75 | 6.12 |
| -5.62 | 6.00 | 6.50 |
| -5.75 | 6.25 | 6.75 |
| -6.00 | 6.50 | 7.00 |
| -6.25 | 6.75 | 7.37 |
| -6.50 | 7.00 | 7.62 |
| -6.62 | 7.25 | 8.00 |
| -6.87 | 7.50 | 8.25 |
| -7.12 | 7.75 | 8.50 |
| -7.25 | 8.00 | 8.87 |
| -7.50 | 8.25 | 9.12 |
| -7.75 | 8.50 | 9.50 |
| -7.87 | 8.75 | 9.75 |
| -8.12 | 9.00 | 10.12 |
| -8.37 | 9.25 | 10.37 |
| -8.50 | 9.50 | 10.75 |
| -8.75 | 9.75 | 11.00 |
| -8.87 | 10.00 | 11.37 |
| -9.37 | 10.50 | 12.00 |
| -9.75 | 11.00 | 12.75 |
| -10.12 | 11.50 | 13.37 |
| -10.50 | 12.00 | 14.00 |
| -10.87 | 12.50 | 14.75 |
| -11.25 | 13.00 | 15.50 |
| -11.62 | 13.50 | 16.12 |
| -12.00 | 14.00 | 16.75 |