Why cold saline makes insertion harder
When a lens full of cold saline touches your eye, the surprise can set off a blink or a flinch. That reflex is often what pulls the lens away from your eye at the last moment and leaves an air bubble, which then means taking the lens out and starting again.
Wearers describe this most in winter, in cold bathrooms, and with saline stored somewhere chilly. Some people with very sensitive or painful corneas find cold fill uncomfortable at any time of year.
A common tip, passed between wearers and often suggested by fitters, is to take the chill off the saline before you fill the lens. Many wearers say it made the difference between struggling for weeks and inserting on the first try.
How wearers warm saline
The aim is comfortably neutral, close to skin temperature, never hot. The methods wearers describe all warm the vial while it is still sealed:
- In your hand. Hold the closed vial in your palm for a minute or two while you wash up and set out your supplies.
- In a pocket. Some wearers carry the next vial in a trouser or shirt pocket for a while before inserting.
- In a cup of warm water. Stand the sealed vial in warm (not hot) water for a few minutes. Then dry it completely, and dry your hands, before you open it.
Before filling, some wearers test a drop on the inside of the wrist. If it feels warm rather than neutral, wait.
Do
- Warm the vial while it is still sealed.
- Dry the vial and your hands before opening it.
- Test a drop on your wrist: it should feel neutral, not warm.
- Use a fresh vial each time, as your fitter directs.
Don’t
- Microwave saline, or heat it on a stove, radiator, or hair dryer.
- Let any tap water reach the lens, the plunger, or the inside of the vial.
- Warm and reuse a vial you opened earlier.
- Fill the lens with saline that feels hot.
Never microwave it
A microwave can’t be set to heat a few milliliters of liquid gently, and a plastic vial isn’t designed for it. Saline that is too hot can hurt your eye. Hand warmth or a cup of warm water gives you control; a microwave doesn’t.
Check the label
Every saline and solution comes with its own directions, including how to store it. The FDA advises following all labeling instructions for lens care products and not using solutions past their expiration or discard date.[1] If the box gives a storage range, gentle hand warming before use is a very different thing from storing the product somewhere hot, but if you’re unsure, ask.
Manufacturers’ advice differs by product. For example, one maker of scleral lens care solutions tells customers that products arriving hot or frozen from shipping should be allowed to come back to room temperature naturally, and not reheated or refrigerated.[2] That advice is about its own cleaning and care solutions, not fill saline, but it shows why reading each label matters. For storage in hot cars and freezing weather, see can heat or freezing damage scleral lenses or solutions?
What wearers say
Most wearers who mention warming their saline describe it as a small change that helped a lot, especially while learning. Some say it ended their blink reflex entirely, others that it made the lens feel barely noticeable going in. People with nerve-related eye pain sometimes say cold fill is the part that hurts most.
Not everyone agrees. Some wearers find room-temperature or even cool saline refreshing and never warm it. A few prefer not to heat plastic vials at all and stick to hand warmth. There’s no single right answer, which is why it’s worth asking your fitter.
What to ask your fitter
- Is it OK to warm my saline before filling, and how?
- Does my saline’s label say anything about storage temperature I should know?
- I keep flinching at insertion. Could anything else help, like a stand or a lighted plunger?
- My eye is painful with cold fill. Should we look into why?
For more on getting the lens in without a blink, see blinking during insertion, how to insert, and saline and solutions.
Common questions
How warm should the saline be?
Wearers aim for roughly skin temperature: it should feel neutral, not warm, when a drop lands on the inside of your wrist. If it feels hot at all, let it cool before you fill the lens. Your eye is far more sensitive than your hand.
Can I microwave the vial for a few seconds?
No. You can't control how hot a microwave makes a small amount of liquid, and a plastic vial isn't made for it. Use your hands, a pocket, or a cup of warm tap water around the sealed vial instead.
Is it OK to stand the vial in tap water?
Wearers commonly stand the sealed, unopened vial in a cup of warm water and then dry it thoroughly before twisting it open. Tap water must never reach the lens, the inside of the vial, or your plunger, so dry the vial and your hands before you fill.
Some people say warming plastic vials is a bad idea. Who's right?
Wearers disagree. Some never warm their saline and find cool fill refreshing. Others say warming is the only way they can insert without blinking. Gentle warmth in your hand is the most cautious approach. Ask your fitter what they suggest for your saline.
My eye still flinches with warm saline. What else helps?
Flinching usually improves with practice. Wearers also find a lighted plunger or stand, holding both lids firmly at the lash line, and looking straight into the light helpful. See our guide on blinking during insertion.