Eyewear Shelf

Online Eyewear Shops Compared: Prescription Range, Lens Index, and Return Policy

2026.07.03

EyeBuyDirect, spring 2022: buy one pair, get a second one free. I did the math, ordered two frames, and didn't think much more about it until the second pair showed up single-vision only -- no cylinder correction at all, on a prescription that has had astigmatism in it since my twenties. Nobody flagged that at checkout; it's just how their BOGO promo locks the free pair. I wore them anyway for about six weeks because I'm stubborn, everything looked very slightly smeared, and I finally dug my RX card back out and realized what had happened. That's the order that got me actually reading the fine print on what each shop's prescription range covers before I click buy, instead of after.

So here's the running sheet I check against now: sphere and cylinder limits, which lens indices each shop actually stocks, and how many days you get if the pair that shows up isn't the pair you ordered. I keep this updated the same way I keep my own order log updated -- by actually calling up the current help page for each shop and reading it, not by trusting whatever I wrote down two years ago. A few of these changed since I first built the sheet; GlassesUSA's return window got longer, Firmoo's numbers turned out to be listed on a completely different help page than I'd bookmarked, and Coastal -- worth flagging on its own -- doesn't really exist as a separate shop anymore. Its help page now forwards straight to EyeBuyDirect's contact form. Same company, one less option than it looks like from the outside.

Comparison of Online Eyewear Shops

Prescription ranges below are single-vision unless the cell says otherwise -- progressive and bifocal limits usually run narrower, so don't assume the sphere ceiling in this table also applies to a progressive order. Where a shop's own help page didn't give me a number, I left the cell blank instead of guessing at one.

Retailer Prescription Range (SPH/CYL) Available Lens Indices Return Policy
Zenni Optical SPH: -20.00 to +12.00; CYL: ±6.00 [1] 1.50, 1.57, 1.61, 1.67, 1.74 14 days for refund to original payment method; 30 days for store credit [2]
EyeBuyDirect SPH: ±9.25 and above; CYL: ±4.25 to ±6.00 (1.74 index) [3] 1.50, 1.57, 1.59, 1.60, 1.67, 1.74 30-day free returns (replacement or refund); separate 365-day guarantee limited to craftsmanship defects [4]
Warby Parker 1.67 recommended for ±4.00 to ±8.00; 1.74 recommended for ±8.00+ [5] 1.50 (Polycarbonate), 1.67, 1.74 30 days for refund or exchange [6]
GlassesUSA Distance: up to -14.00; Near: up to +9.00 [7] 1.50, 1.59, 1.61, 1.67, 1.74 [8] 60-day risk-free guarantee (exchange, store credit, or refund) [9]
Clearly (Canada) Not published -- contact support to confirm a strong prescription before ordering 1.50, 1.59, 1.67 30 days from delivery date for a full refund or exchange [10]
Zeelool SPH: -20.00 to +12.00 (1.74 High-Index) [11] 1.57, 1.61, 1.67, 1.71, 1.74 [12] 30-day exchange & return; 365-day warranty [13]
Firmoo SPH: -18 to +10; CYL: -4.50 to +4.50 [14] 1.50, 1.56, 1.60, 1.67, 1.74 [15] 365-day warranty; 60-day exchange & return window [16]
Vooglam SPH: -20.00 to +12.00 (1.74 High-Index) [17] 1.57, 1.61, 1.67, 1.71, 1.74 [18] 30-day return & refund; separate 365-day quality warranty [19]
LensCrafters (Online) SPH: -14 to +8, single vision (no decimal precision published) [20] 1.50, 1.59, 1.67, 1.74 30 days from date of dispense, replace or refund [21]
Target Optical (Online) Standard Luxottica Range (Target Optical is EssilorLuxottica-licensed, same lab network as LensCrafters) 1.50, 1.59, 1.67, 1.74 90-day guarantee ("No hassle, just happiness") -- full refund, free return shipping [22]

Technical Definitions and Lens Indices

Sphere (SPH)
The primary power of the lens, measured in diopters. Negative values indicate nearsightedness (myopia), while positive values indicate farsightedness (hyperopia).
Cylinder (CYL)
The lens power required to correct astigmatism. If this field is blank, the eye is spherical and does not require astigmatism correction. (Mine is never blank, which is the whole reason this table exists.)
Lens Index (Refractive Index)
A numerical value representing how efficiently a material bends light. Higher indices allow for thinner lenses in stronger prescriptions.
1.50 Index (Standard)
Conventional plastic (CR-39) lenses. Best suited for weak prescriptions between SPH -3.00 and +3.00.
1.57 - 1.61 Index (Mid to High)
Thinner than standard plastic. Recommended for moderate prescriptions to reduce edge thickness and weight.
1.67 Index (High Index)
Significantly thinner and lighter. Typically recommended for prescriptions above +/- 4.00 diopters.
1.74 Index (Ultra High Index)
The thinnest plastic lens material available. Recommended for very strong prescriptions (typically +/- 8.00 diopters or higher) to minimize the "coke bottle" effect.
Polycarbonate (1.59 Index)
A highly impact-resistant material often used for sports eyewear and children's glasses. It is thinner than 1.50 plastic but has lower optical clarity (Abbe value).
Trivex (1.53 Index)
A lightweight, impact-resistant material that offers superior optical clarity compared to polycarbonate. [23]
Prism Correction
Used to treat eye alignment issues or double vision. Many online retailers have strict limits on prism (often up to 5.00 diopters) or do not offer it online due to the need for precise physical measurements.

None of this replaces actually reading your own RX card before you check out. I compare every number in that table against my current card, not against what I remember ordering last time -- PD and lens material especially, since those are the two fields I've mistyped before. Coatings are the other thing I always check by hand: anti-reflective and scratch coatings wear at wildly different rates shop to shop, kind of like how one detergent leaves your towels scratchy after twenty washes and another one doesn't -- you don't find out which is which by reading the bottle, you find out by living with it. I don't have a clean verified number for that one, so it's staying out of the table above; this page only gets a line item once I can point at where it came from.

Last verified: 2026-07-17

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