How to tell if your contact lenses are inside out

Inserting a contact lens the wrong way round doesn’t just reduce how well it corrects your vision — it can also feel uncomfortable and may irritate your eye if worn for too long.

The problem is that it isn’t always obvious when a lens is inside out, especially for new wearers.

This guide explains several simple methods you can use to check lens orientation quickly and confidently every time.

Quick Answer: How Do You Know If a Contact Lens Is Inside Out?

A contact lens is inside out if the edges flare outward instead of forming a smooth bowl shape. You can check this using the side look test, the taco test, or by looking for laser markings on the lens. Wearing an inside-out lens can cause discomfort, redness, and blurry vision.

Key takeaways:

• Correct contact lenses look like a smooth cup with edges pointing up
• Inside-out lenses have edges that curl outward
• Use the taco test for a quick double-check
• If irritation continues, consult your optician

Before You Start: Wash Your Hands

Always wash your hands thoroughly with antibacterial soap and dry them with a clean, lint-free towel before handling contact lenses.

This reduces the risk of irritation or infection.

3 Easy Ways to Check If Your Lens Is the Right Way Round

1. The Side Look Test (Most Common Method)

This is one of the easiest ways to check lens orientation.

Step-by-step

1. Find a well-lit area
2. Place the lens on the tip of your finger
3. Hold it at eye level
4. Look closely at the lens edges

What to look for

• Correct way round: edges point straight up, forming a neat bowl
• Inside out: edges roll outward or flare away from the centre

If the lens looks more like a saucer than a cup, flip it back.

Side look

2. The ‘Taco’ Test

The taco test is a quick and reliable method, especially if you’re unsure after the side look.

Step-by-step

1. Hold the lens gently between your thumb and forefinger
2. Lightly squeeze as if folding it in half

What it means

• Correct orientation: edges curve inward and meet neatly
• Inside out: edges bend outward toward your fingers

Think of it like folding a taco — the edges should come together naturally

3. Check Laser Markings (If Your Lens Has Them)

Some contact lenses include small laser markings, often numbers or letters.

How to check

1. Place the lens on your fingertip
2. Hold it up to a bright light
3. Look for the marking

What to look for

• If the letters/numbers read correctly → lens is the right way round
• If they appear reversed → lens is inside out

Not all lenses have markings, but they can be very helpful if available.

Check laser markings

What Happens If You Wear a Lens Inside Out?

Wearing an inside-out contact lens may cause:

• Discomfort or a gritty feeling
• Redness or watering
• Blurry vision
• Lens movement that doesn’t feel stable

If this happens, remove the lens, flip it the correct way, rinse with solution, and try again.

When to Get Professional Advice

If you continue to experience discomfort, blurred vision, or problems with lens fit, it’s best to speak to an optician.

Lenstore customers in the UK may be eligible for a free contact lens check and eye test appointment with Vision Express through Lenstore’s partnership.