Last Updated: February 2026 | Reviewed by Dr. Davinder Sidhu, OD
A -7.5 prescription means you have high myopia — your distance vision without correction is significantly blurred. But "bad" depends on what you're comparing it to. You can see. You can function. And with the right lenses, you'll hit 20/20 or close to it. The real concern with -7.5 isn't the blur — it's the structural changes happening inside your eye that you can't feel.
What Does a -7.5 Eye Prescription Actually Mean?
A -7.5 dioptre prescription means your eye is too long from front to back, so light focuses in front of your retina instead of on it. Everything past about 13 centimetres from your face looks blurry without glasses or contacts. That's roughly the length of a pen.
I had a patient last year — university student, -7.25 in one eye, -7.75 in the other. She told me she'd been wearing the same glasses since grade 10. "They still work fine," she said. They didn't. Her prescription had drifted by almost a full dioptre, and she'd just gotten used to squinting. That happens more than you'd think.
To be specific: the minus sign means you're nearsighted (myopic). The 7.5 is the optical power needed to correct your vision. Anything beyond -6.00 is classified as high myopia by the World Health Organization's 2015 report on myopia prevalence.
Is -7.5 Eyesight Considered Bad?
By clinical standards, yes — -7.5 falls into high myopia territory. But that label can be misleading. "High myopia" sounds alarming, and optometrists don't always do a great job explaining what it actually means for your daily life versus your long-term eye health.
Daily life: With updated glasses or contacts, most people with -7.5 see perfectly well. You're not going blind. You're not limited in what you can do. Modern lens technology handles -7.5 without the coke-bottle thickness that used to come with strong prescriptions.
Long-term health: This is where it gets serious. High myopia physically stretches the eyeball, and that stretch puts stress on the retina, the optic nerve, and the vitreous gel inside. The Flitcroft et al. (2019) meta-analysis published in Ophthalmology found that for every additional dioptre of myopia beyond -5.00, the risk of retinal detachment roughly doubles.
So no, -7.5 doesn't mean your vision is ruined. But it means you need to take monitoring seriously. Annual dilated eye exams. Not optional.
What Does 6/7.5 Vision Mean on an Eye Chart?
If your eye report says 6/7.5, that's a completely different measurement. This is your Snellen visual acuity — how sharp your vision is with your best correction on.
6/7.5 means that at 6 metres, you can read what a person with "normal" vision reads at 7.5 metres. It's slightly below the 6/6 (or 20/20) benchmark, but honestly? It's very close to normal. Most people with 6/7.5 acuity don't notice any real-world limitation.
| Measurement | What It Tells You | -7.5 Means | 6/7.5 Means |
|---|---|---|---|
| Type | Prescription power vs. clarity | How strong your lens needs to be | How clearly you see with correction |
| Units | Dioptres vs. Snellen fraction | -7.50 D (dioptres) | 6/7.5 (metres) |
| Severity | Classification | High myopia | Near-normal acuity |
| Action Needed | Correction type | Strong corrective lenses + monitoring | Likely fine — recheck in 1-2 years |
People confuse these two measurements constantly. If your optometrist said "6/7.5," you're in good shape. If your prescription says "-7.5," keep reading.
What Are the Real Risks of High Myopia?
Quick anatomy lesson. Your eyeball at -7.5 is roughly 2 mm longer than a non-myopic eye. Doesn't sound like much. It is. That extra length stretches everything — retina, optic nerve, vitreous gel — beyond what those tissues were built for.
Retinal detachment. The stretched retina develops thin spots, especially at the periphery. The Beijing Eye Study (2005) found that eyes with axial lengths above 26.5 mm — typical for high myopia — had significantly higher rates of lattice degeneration, a precursor to detachment. Flashing lights, new floaters, a shadow in your peripheral vision — any of those and you need to be seen the same day.
Myopic macular degeneration. Different from age-related macular degeneration. This is stretch damage to the macula — the centre of your retina responsible for sharp detail vision. The Hisayama Study (Iwase et al., 2006) linked pathologic myopia to progressive central vision loss in roughly 10% of highly myopic individuals over a 5-year period.
Glaucoma. High myopia increases your risk by 2-3x compared to emmetropic (non-prescription) eyes, according to the Blue Mountains Eye Study (Mitchell et al., 1999). The optic nerve is already under structural stress from the elongated globe.
Cataracts. Earlier onset. The Beaver Dam Eye Study data showed myopes develop nuclear cataracts roughly a decade sooner than non-myopes.
None of this is meant to scare you. It's meant to get you into your optometrist's chair regularly. Caught early, most of these conditions are manageable.
Can -7.5 Eyesight Be Corrected?
Yes. And honestly, the options now are better than they were even five years ago.
Glasses. The go-to. With high-index 1.74 lenses, even a -7.5 prescription doesn't have to look thick. Aspheric designs flatten the profile further. If your optician is still putting -7.5 into a standard 1.50 index lens, find a different optician.
Contact lenses. Daily disposables work well at this power. Brands like Acuvue Oasys 1-Day and Dailies Total 1 are available in -7.5. Toric options exist if you've got astigmatism on top of it. For Canadian winters specifically, contacts avoid the constant fogging issue that drives glasses-wearers nuts when you walk indoors.
LASIK / PRK. Possible, but the margin for error tightens at -7.5. Most surgeons will treat up to about -8.00, but your cornea needs to be thick enough to safely reshape. If it's on the thin side, PRK might be offered instead of LASIK, or you might be steered toward an ICL.
ICL (Implantable Collamer Lens). This is where high myopia correction has gotten genuinely exciting. A thin lens is placed behind your iris, in front of your natural lens. No corneal tissue removed. The Visian ICL has been approved in Canada for prescriptions up to -18.00, and the visual quality at -7.5 is often better than LASIK outcomes at the same power. I've been referring more patients to this option over the past few years.
Can You Slow Down -7.5 Myopia From Getting Worse?
If you're an adult and your prescription has been stable for 2-3 years, it's likely staying put. Myopia progression typically plateaus in the mid-twenties.
If you're a parent reading this because your child is heading toward -7.5 — that's a different conversation, and an urgent one. The IMI (International Myopia Institute) 2019 guidelines outline three evidence-backed interventions for myopia control in children:
Low-dose atropine drops (0.01%-0.05%). Slows axial elongation by roughly 50% in clinical trials. Available by prescription in Canada.
Orthokeratology (Ortho-K). Rigid lenses worn overnight that temporarily reshape the cornea. The SMART Study (Santodomingo-Rubido et al., 2017) showed a 52% reduction in myopia progression over two years.
Time outdoors. The CLEERE Study (Jones et al., 2007) found that children spending 14+ hours per week outdoors had significantly lower myopia progression. Canadian winters make this harder — but even overcast daylight helps. The mechanism appears to be dopamine release in the retina triggered by bright ambient light.
What about eye exercises? The Bates Method? Pinhole glasses? I'm going to be direct: there's no clinical evidence that any of these reduce a myopic prescription. Zero. I'm still not fully convinced we have a perfect myopia control protocol — atropine concentrations keep getting debated, and long-term data beyond 5 years is thin. But we know enough to act. If your optometrist hasn't brought up myopia control for your child, ask about it at the next visit.
When Should You See Your Optometrist?
With -7.5 myopia, the standard "every two years" recommendation doesn't apply to you. You need annual comprehensive exams with dilation. Here's why: the conditions associated with high myopia — retinal tears, lattice degeneration, vitreous changes — often have no symptoms until something goes wrong.
See your optometrist urgently if you notice:
- Sudden new floaters (especially a shower of small ones)
- Flashing lights in your peripheral vision
- A curtain or shadow appearing from one side
- Sudden blurred vision that doesn't clear with blinking
I can't stress this enough. A patient walked into my clinic two months ago — -8.00, hadn't been examined in four years. "My glasses still work." Turned out he had a horseshoe tear in his left retina. We caught it, got him to a retinal specialist the same week for laser retinopexy. If he'd waited another few months? Possibly a full detachment and emergency surgery.
Frequently Asked Questions
Is -7.5 legally blind?
No. Legal blindness in Canada is defined as best-corrected visual acuity of 20/200 (6/60) or worse, or a visual field of 20 degrees or less. A -7.5 prescription corrected with glasses or contacts typically achieves 20/20 or near it. Without correction your vision is very blurred, but that's not the same as legal blindness.
Is 6/7.5 vision bad?
Not really. 6/7.5 is one line below 6/6 (20/20) on the Snellen chart. Most people with this acuity function without any issues. It easily meets the visual standard for a Canadian driver's licence, which requires 6/12 (20/40) or better.
Can -7.5 myopia lead to blindness?
Untreated complications from high myopia can cause severe vision loss — particularly myopic macular degeneration and retinal detachment. But with regular monitoring and early intervention, the vast majority of people with -7.5 maintain functional vision throughout their lives. The key word is "regular monitoring."
Does -7.5 eyesight keep getting worse?
In most adults, myopia stabilizes by the mid-to-late twenties. Small shifts of 0.25-0.50 dioptres can happen over years, but dramatic progression in adulthood is uncommon. If your prescription is still climbing after age 25, your optometrist should investigate possible causes like corneal ectasia or early nuclear sclerosis.
About the Reviewer
Dr. Davinder Sidhu is an optometrist based in British Columbia with a focus on dry eye management and preservative-free solutions. Learn more at TheGenuwineOD.com or follow him on Instagram and Facebook.
