Cycloplegic Refraction Calculator is used to determine an individual’s refractive error, i.e., their need for corrective lenses such as glasses or contact lenses. This type of refraction is performed under cycloplegia, a state induced by eye drops that temporarily paralyze the ciliary muscle. The purpose of cycloplegic refraction is to obtain the most accurate prescription, especially for children or individuals with accommodative issues.
The Formula
The heart of cycloplegic refraction lies in its formula:
Cycloplegic Refraction = Sphere (S) + Cylinder (C) × Axis (A)
- Sphere (S): This represents the overall refractive power, with values indicating nearsightedness (negative) or farsightedness (positive).
- Cylinder (C): It signifies astigmatism, a common condition causing blurred vision due to irregularly shaped corneas or lenses.
- Axis (A): The axis denotes the orientation of the astigmatism, measured in degrees.
Now, to simplify this process for you, let’s create a handy reference table:
Cycloplegic Refraction Conversion Table
| Sphere (S) | Cylinder (C) | Axis (A) | Cycloplegic Refraction |
|---|---|---|---|
| -3.00 D | -1.25 D | 75° | -4.75 D |
| +1.50 D | -0.75 D | 105° | +0.75 D |
| -4.25 D | -2.50 D | 30° | -6.75 D |
Example of Cycloplegic Refraction Calculator
Let’s walk through an example to illustrate how the cycloplegic refraction formula is applied. Suppose you have a patient with the following values:
- Sphere (S): -2.00 D
- Cylinder (C): -1.50 D
- Axis (A): 90°
Using the formula, the cycloplegic refraction is calculated as follows:
Cycloplegic Refraction = -2.00 D + (-1.50 D) × 90° = -2.00 D – 1.50 D = -3.50 D
Hence, the patient’s cycloplegic refraction is -3.50 diopters.
Most Common FAQs
Cycloplegic refraction is essential, particularly for children, as it provides the most accurate prescription by eliminating the eye’s ability to accommodate.
Common side effects include light sensitivity and blurred vision, but these are temporary and usually subside within a few hours.
The frequency depends on the individual’s age and eye health. Children often require cycloplegic refraction annually, while adults may need it less frequently.