Are contact lens prescriptions the same as glasses?
Both prescription glasses and contact lenses are designed to correct vision for daily use, but they cannot share the same prescription due to their lens type. In another article, learn how to read them. If you wear contact lens, or prescription glasses or both, your optometrist will write 2 seperate prescriptions for you as the picture below. So what's the difference between these two kinds of prescriptions and why can't use them interchangeably?
1 Lens Power Differences:
The power needed for contact lenses might differ slightly from glasses. This is because contact lenses sit directly on the cornea, while glasses are positioned a small distance away from the eyes. This positional difference can affect the corrective power required.
2 Specific Measurements to Contact Lenses:
Except the same Sphere (SPH), Cylinder (CYL), Axis and Addition (ADD) measurements, contact lens Rx require some extras:
The base curve and diameter are crucial for contact lenses to ensure they fit comfortably and securely on the eye. These measurements are not required for glasses, as glasses sit at a distance from the eyes.
3 Prescription Validity:
Contact lens prescriptions often require more frequent updates compared to glasses prescriptions. This is due to the need for regular eye health assessments and to ensure the lenses continue to fit well and provide adequate vision correction. The contact lenses must conform to the curvature of your eye, requiring precise measurements to avoid discomfort or potential damage. Glasses, however, do not need to fit the eye’s surface and thus have different measurement criteria.
Using contact lens prescription to place the prescription glasses online will not only can't correct your vision correctly but also cause eye health issues. If you need prescriptions for both glasses and contact lenses, make sure to consult your eye doctor to get a full prescription form before purchase.
