Make Your Own Saline Solution

If you wear contact lenses you probably know how exorbitant the various consumable supplies can be. You can make your own saline solution very cheaply because the main ingredients are just water and salt. Here's how to do it along with a couple of other tips on reducing costs:

Buy some distilled (or de-ionised, or de-mineralised) water. You should be able to find it with the laundry supplies in your supermarket (it's used for steam irons), in a hardware store, or an auto store (for topping up car batteries). I suggest buying at least a litre or a quart, and preferably twice this much. It's cheap stuff: around 2-3 dollars for 2 litres (half-gallon) here in Australia.
The other supply you need is salt. In the absence of laboratory grade sodium chloride, I recommend cooking salt because table salt seems to have silica-type minerals added to make it free-flowing. Silica is exactly the sort of insoluble gritty stuff you don't want in your solution. The cooking salt should probably be plain rather than iodised (though I've used the latter myself), as I can't say what long-term effects, if any, the trace amounts of iodine might have.
If you can find a clean, sterile container that holds a litre or a quart, this will be handy too. You could use a well-cleaned plastic soft-drink bottle. Rinse it well with water that has been well boiled, then give it a small final rinse or two with some fresh distilled water. To really give your containers a thorough sterilisation, you could use a solution made with sterilising powder from home brew or winery supply shops. However, you'd have to use a fair bit of distilled water to rinse it out completely. Several small rinses are generally much more effective than one large rinse.
Now comes the only hard part: approximating the correct amount of salt. You are aiming for 8 grams per litre to make "normal saline" as it's called. If you have access to laboratory or jeweller's scales you'll be laughing. You can buy electronic jewellers scales fairly cheaply on eBay these days. Otherwise, use a teaspoon measure of the kind that is used for cooking. Make sure it's clean and sterile (boiling water is a good steriliser). A teaspoon holds about 5 mls, so allowing for the density of salt, I find that a very slightly heaped teaspoon is perfect for a litre of water. A quart is close enough to a litre that you don't have to worry if that's what you have - just make sure it's a very full quart.
As you can see, this is all very rough and approximate but I've found that it doesn't matter. You don't need precision and your eyes won't feel the difference. It's better to err on the side of a weaker solution if anything, because too much salt will make your eyes sting slightly whereas too little will just produce a vaguely uncomfortable suction until the osmotic pressures equalise. You probably know the feeling if you've ever had distilled or tap water in your eyes. If you find that you've made a solution that's too strong, add more water (which is why it's nice to have some spare).
Keep the solution in a dark place and/or a dark bottle so that algae doesn't grow in it. Keep the lid tight. I suggest refilling smaller squirt-bottles and using these on a day-to-day basis. You can often prise the cap off a commercial saline or disinfecting solution bottle and reuse it repeatedly as long as you maintain its sterility. Keep the caps and bottle tops away from surfaces if possible. Open the bottles only briefly.
Don't use home-made saline if you're disinfecting your lenses with heat. Commercial salines are pH-buffered. If you cook your lenses in a slightly acidic solution repeatedly, it will probably damage them (I did this a long time ago when heat disinfection was popular). Remember also that this home-made solution is not actively sterilised. Take care when preparing it, and you should find that it's fine for rinsing, enzyme cleaning, and so on, but not for your daily sterilisation. You will still need to use a commercial sterilising solution. However the beauty is that you can now cheaply rinse the sterilising solution off and avoid putting all those chemicals into your eyes every day. A few drops of colloidal silver solution (from your heath food shop) in the saline bottle might act as a useful preservative if you are concerned about ensuring its sterility over time.
Also, don't be too worried about rinsing your lenses in tap water as long as you follow the rinse with disinfection. Don't deliberately put tap water in your eyes as there really are bugs that can cause very nasty effects in rare cases (a higher prevalence in the UK than other developed countries too). I clean my lenses each night with daily cleaner then wash this off with tap water followed by last night's leftover sterilising solution before popping the lenses into clean sterilising solution for the night. I minimise my consumption of sterilising solution by using lens storage cases with rounded bottoms. Lens supply companies like to produce big flat-bottomed tubs for you to store your lenses in because it forces you to use heaps of their product. Two or three drops per lens is about enough to cover mine in their profiled cases. I don't know if you can still buy such lens cases these days.
In the morning I wash the sterilising solution off my lenses with home-made saline before putting them in my eyes.
When you get to the bottom of your main saline storage bottle, throw out the dregs and rinse the bottle well before mixing up the next batch. I find that cooking salt is not totally pure, and any insoluble bits sink to the bottom. You can sterilise both the main storage bottle and the daily squirt bottle between refills.
I make no claims as to the safety of the above. Assess this material for yourself and follow these instructions at your own risk. If you do choose to make your own saline, use it externally only (don't go injecting anyone with it). While the two of us have used home-made saline for years, and I see no reason why the dangers would exceed normal daily exposure to microbes, I am not an expert and there are, as always, risks associated with such homespun formulations that you must bear yourself. You will be trusting your supply of salt and water to be free from harmful substances, for example.
For those of you who proceed, I hope you enjoy freedom from being ripped off as much as I do.

 

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