Grass seeds become common and prevalent during the autumn months. When your dogs are playing outside, they can brush up against tall grass seeds at eye-level. Unfortunately, the grass seeds can become stuck behind the dog's third eyelid. (The third eyelid is a clear, retractable protector that slides over the dog's eye.) Unfortunately, other than preventing your dog from running through brush, there is no fool-proof prevention. All you can do is to treat the injury if it occurs.
First, you'll need to assess whether your dog has a grass seed in her eye. If a seed is present, you'll notice your dog squinting while outside, or immediately after your dog comes indoors. If the squinting is there and if it persists, it is likely a grass seed is there. Now, it will need to be removed.
If you tend to get a little squeamish, if you don't have extremely steady hands, or if you are not confident that your dog will stay perfectly still during removal, it is best to take a quick trip to your veterinarian. If you plan to try to remove the seed yourself, you first need to apply an eye-numbing agent, such as Proparacaine, which your vet can provide.
Next, lift the third eyelid using tweezers. This is when steady hands, and your dog remaining perfectly still, will be necessary, as your dog's eye will be very vulnerable and easy to injure at this point. Now, carefully grab the grass seed with your fingertips, and remove it from your dog's eye. Make sure you do not push the seed along the eyeball with your finger, because scratching could occur.
If your dog's eye continues to water and/or if squinting persists, take your dog to the vet to be checked.