Decoding Your Rx: How to Calculate Your Prescription for Swim Goggles

ou’ve got your eyeglass prescription in hand, and you’re ready to order those game-changing prescription swim goggles. But how do you translate all those numbers and abbreviations into the right strength for your swimming goggles? Don't worry, it's simpler than it looks! This step-by-step guide will empower you to read your eyeglass prescription and confidently choose the correct diopter strength for your new underwater vision.

Understanding Your Eyeglass Prescription

Your eyeglass prescription typically contains several abbreviations and numbers. Let's break down the most common ones:

• OD (Oculus Dexter): Refers to your right eye.
• OS (Oculus Sinister): Refers to your left eye.
• SPH (Sphere): This is the main power of the lens, indicating the degree of nearsightedness (-) or farsightedness (+). This is the most crucial number for choosing standard prescription swim goggles.
• CYL (Cylinder): This indicates the amount of astigmatism, a common condition where the eye's curvature is irregular.
• AXIS: This number (between 1 and 180) indicates the orientation or angle of your astigmatism.
• ADD (Reading Add Power): This is for multifocal or bifocal lenses, indicating the added magnifying power for reading. This value is generally not used for swimming goggles, as swim goggles are typically single-vision.

Step-by-Step: Translating Your SPH for Swim Goggles

Most standard prescription swim goggles are designed to correct spherical power (SPH). Here's how to calculate the appropriate diopter strength:

1. Locate Your SPH Value: Find the "SPH" column for both your OD and OS eyes.
2. Identify the Sign: Note whether the SPH value is positive (+) for farsightedness or negative (-) for nearsightedness. Most commonly, swimming goggles are purchased for nearsightedness.
3. Choose the Closest Available Diopter: Prescription swim goggles typically come in increments of 0.5 diopters (e.g., -2.0, -2.5, -3.0).
   • For Nearsightedness (Negative SPH): It's generally recommended to round down to the nearest 0.5 diopter. For example, if your SPH is -2.75, you would typically choose a -2.50 lens. If your SPH is -2.25, you would choose -2.00. A slight under-correction can often feel more comfortable in the water.
   • For Farsightedness (Positive SPH): If you find swimming goggles with positive powers, round to the nearest 0.5 diopter, or consult with an optician. Positive powers are less common in off-the-shelf prescription swim goggles.
4. Consider Each Eye Separately: If your OD and OS SPH values are different, you will need to select different diopter strengths for each lens of your swimming goggles. Many brands sell individual lenses that can be snapped into a universal goggle frame.

Example:

• OD SPH: -3.25 $\to$ Choose -3.00 for the right lens.
• OS SPH: -2.75 $\to$ Choose -2.50 for the left lens.

Dealing with Cylinder (Astigmatism)

Standard off-the-shelf prescription swim goggles typically do not correct for astigmatism (CYL and AXIS values). However, here's how to approach it:

• Mild Astigmatism (CYL up to -0.75): Many people with mild astigmatism find that standard spherical correction is sufficient for swimming goggles. The environment underwater, with its inherent blur, often makes minor astigmatic errors less noticeable.
• Moderate to High Astigmatism (CYL -1.00 or higher): If your astigmatism is significant, you may experience residual blur with standard spherical goggles. In this case, you have a few options:
  1. Try Spherical Correction: You can still try the spherical equivalent, rounding down your SPH. For some, this might provide enough clarity.
  2. Consult a Specialist/Custom Goggles: For optimal vision with significant astigmatism, you might need to look into custom-made prescription swim goggles that can incorporate your CYL and AXIS values. These are less common and typically more expensive but offer the most precise correction.
  3. Spherical Equivalent Calculation (with caution): For a rough approximation, you can calculate the "spherical equivalent" by taking half of your CYL value and adding it to your SPH.
     • Formula: SPH + (CYL / 2) = Spherical Equivalent
     • Example: If SPH is -3.00 and CYL is -1.00, the spherical equivalent is -3.00 + (-1.00 / 2) = -3.00 - 0.50 = -3.50.
     • Important Note: Use this method with caution and understand it's an approximation. It's often still best to round down the SPH value for comfort in swimming goggles.

Important Considerations

• No ADD Power: As mentioned, the ADD power on your prescription is for reading vision and is not typically used for swimming goggles.
• Pupillary Distance (PD): While less critical for off-the-shelf swimming goggles that often have adjustable nose bridges, PD (the distance between the centers of your pupils) is essential for custom orders to ensure the optical center of the lens aligns with your eyes.
• Trial and Error: Sometimes, finding the perfect prescription swim goggles involves a bit of trial and error, especially if your prescription is unusual. Many online retailers have good return policies.
• Consult an Optician: If you're unsure about your prescription or how to choose the right strength, always consult with an optometrist or optician. They can provide personalized advice.

Armed with this knowledge, you can confidently decode your eyeglass prescription and select the ideal prescription swim goggles to enjoy clear, unhindered vision on your next aquatic adventure!

Prescription Swim Goggles – Sports Goggles – Ski Goggles

LEADER IN PRESCRIPTION GOGGLES AND GLASSES

Kids RX Swim Goggles – Adult RX Swim Goggles – Prescription Sports Goggles - RX Ski Goggles