Expert tips, lens guides, and eye health advice from our licensed opticians
Our clinical team put the OASYS MAX through 6 months of real-world testing. The results surprised us — especially for heavy screen users.
Your contact lens prescription looks like a cryptic string of numbers and abbreviations — but once you know what each term means, it's straightforward. This guide walks through every field you'll see on a typical prescription card.
OD (from Latin oculus dexter) always refers to your right eye. OS (oculus sinister) is your left eye. Some prescriptions also list OU (both eyes together). If your prescription is the same for both eyes, you may see a single set of values with "OU" or the same values repeated.
Sphere is the primary power of your lens, measured in diopters (D). A negative number (e.g., −3.50) means you are nearsighted — you can see up close but struggle at distance. A positive number (e.g., +2.00) means you are farsighted. A prescription close to 0.00 indicates mild correction or no correction needed.
If you have astigmatism, your prescription will include a CYL value and an Axis. The cylinder describes the power difference across the two meridians of your eye, and the axis (0–180°) describes the orientation. If these fields are blank or 0, you don't have significant astigmatism — you'll use standard spherical lenses. If they have values, you need toric lenses (such as ACUVUE OASYS for Astigmatism or AIR OPTIX for Astigmatism).
The Add or ADD power appears on prescriptions for presbyopia — the age-related loss of near vision that typically begins in your 40s. It's always a positive value and is usually listed as Low, Mid, or High (or as a numeric value like +1.75). This value tells the lens manufacturer how much additional reading power to build into the lower portion of a multifocal lens.
Base Curve describes the curvature of the back surface of the lens (how it fits against your eye). Most soft contact lenses come in a BC of 8.3–9.0 mm. Diameter is the width of the lens across its center, typically 13.8–14.5 mm. Some prescriptions list these; others leave them blank because the brand is pre-specified.
Your prescription is brand-specific — it was written for the exact lens you were fitted with. If you want to switch brands, your eye doctor must refit you. Prescriptions in the US expire after 1 year (some states allow 2 years). An expired prescription cannot be used to order lenses.
The question we hear most often: "Are daily lenses really worth the extra cost?" The honest answer is it depends on how often you wear lenses — but the math often surprises people.
A 90-pack of daily lenses covers 45 days of wear (one pair per eye per day). At GenericContacts.com, popular daily lenses range from $38–$65 per 90-pack. If you wear lenses every day of the year, you'll need about 8 boxes — coming to $304–$520/year. The upside? Zero solution cost, maximum convenience, and the cleanest lens wear possible.
A 6-pack of monthly lenses provides 6 months of wear. At $35–$55 per 6-pack, two boxes cover a full year at $70–$110 for the lenses themselves. But add lens solution ($15–$25/month × 12 = $180–$300/year) and the real cost is $250–$410/year — often comparable to or more expensive than dailies.
Daily lenses are the clear winner if you wear contacts fewer than 5 days per week. When you wear fewer days, you open fewer boxes — the per-use cost of monthlies goes up because you're still buying solution and replacing cases. Dailies also win for allergy sufferers (fresh lens = no accumulated pollen), occasional wearers, and anyone who finds lens care inconvenient.
If you wear contacts every single day and are disciplined about lens care, monthly lenses can save you $50–$150/year. They're also the only option for some prescriptions (very high powers, or certain toric/multifocal fits) that aren't available in daily format.
For most contact lens wearers, daily lenses offer the best balance of cost, convenience, and eye health — especially when ordered online at discounted prices. If you currently wear monthlies, try our Lens Finder to see if there's an equivalent daily option within your budget.
Buying GuideFlexible Spending Accounts (FSA) and Health Savings Accounts (HSA) let you pay for qualified medical expenses — including contact lenses — using pre-tax dollars. That means you effectively get a 20–35% discount depending on your tax bracket.
According to IRS Publication 502, the following contact lens-related expenses are FSA/HSA eligible:
An FSA (Flexible Spending Account) is offered through your employer and has a "use it or lose it" rule — unspent funds typically expire December 31. The 2026 contribution limit is $3,300. An HSA (Health Savings Account) requires enrollment in a high-deductible health plan (HDHP) and allows you to roll over unused funds year to year — making it ideal for stocking up on lenses before year-end. HSA funds also grow tax-free if invested.
Your FSA or HSA debit card works exactly like a Visa or Mastercard. At checkout on GenericContacts.com:
If you have remaining FSA dollars in November or December, contact lenses are one of the easiest ways to spend them. A 90-day supply is a smart purchase — lenses don't expire for 1–4 years when unopened. Just make sure you order before your plan's deadline (usually December 31 or March 15 for grace-period plans).
