A leaky or an ill-fitting mask means you're not getting the full air pressure you need, and you may be irritating your skin. The mask can also blow air into your eyes, causing them to become dry or teary.
Try adjusting pads and straps to get a better fit. If the device fits over your nose, make sure it doesn't sit too high on the bridge of your nose, which can direct air into your eyes.
You may need to ask your supplier to help you find a different size mask, particularly if your weight has changed a lot. Or try a different style device such as a nasal pillow. If you develop skin deterioration or sores, such as on your nose, tell your doctor promptly.