Background: Nutritional supplements

The following have been recommended as nutritional supplements:

Beta-carotine

"One solution I’ve recommended is taking beta-carotene (25,000 units a day)." [Source]

Fatty acids

Essential Fatty Acids: These are important for the production of both the oily, lipid and the watery aqueous layers of the tear film. After only ten days of taking essential fatty acids plus vitamins B6 and vitamin C, dry eye sufferers have seen an increase in tear production.

"the lower the ratio of omega-3s to omega-6s the higher the likelihood of dry eye" [Source]

Omega 3

the following foods are rich in omega-3 fatty acids: canola oil, English walnuts, flax oil, ground flax seed, hemp oil, hemp seed, olive oil, pumpkin seeds, and soybeans. [Source]

More commonly fish oil is highly recommended by many websites. This could also help revive the glands. 

Fish and fish oils and / or krill oil are suggested by some websites. Omega 3 fatty acids are found in fish, particularly the highly unsaturated EPA and DHA fatty acids.  

Evidence: "Many of our patients report more comfort and less dryness in a few weeks of taking fish oil." [Source]

Also see this.

“Women with a higher intake of [omega-3 fatty acids] tended to have a lower risk of dry-eye syndrome than did women with a lower intake,” the investigators wrote. They also found the participants to be at a higher risk for dry-eye syndrome if they had a higher dietary consumption of omega-6 acids. Increased tuna consumption—at least five to six times a week—seemed to decrease the risk for dry eye in the study, compared with the participants who ate tuna only once a week or less frequently. 

Flax seed oil capsules taken internally may apparently be helpful. It is suggested by some websites that one can substitute flax seed oil for other types of common cooking oils. (It is best to not heat flax oil. Cooking oils changes their structure and takes away their benefits.) 

3,000 mg a day of omega-3-rich flaxseed oil one week before and one week after LASIK was just as effective as doxycycline for dry eye when patients were seen three months post-op. [Source]

Decrease omega 6 fatty acids

Vitamins and minerals

It is possible that tear glands are not receiving sufficient oils. Here's a remedy (HydroEye) that provides the following dietary supplements which have reportedly helped a lot of people. It contains the following:

• Vitamin A (from retinyl palmitate) 
• Vitamin C (as ascorbic acid) 
• vitamin B6 (from pyridoxal 5-phosphate) 
• Magnesium (from magnesium sulfate) 
• Black Currant Seed Oil [15.6% gamma linolenic acid (GLA)] 
• Mucin Complex (60% mucin) 
• Cod Liver Oil

Here's a website that recommends these vitamins:

Vitamin A: In parts of the world where vitamin A deficiency is widespread, severe dry eye syndrome is a leading cause of blindness. Vitamin A is needed for the health of all epithelial (surface) tissues; it is actually found in the tear film of healthy eyes, and is fundamental to the production of the mucous layer of the tears.

Vitamin B6: All of the B vitamins are important in treating dry eyes, but vitamin B6 aids in the proper absorption of magnesium. Magnesium helps the body produce a hormone called prostaglandin E-7, which is necessary for tear production.

Vitamin C: Vitamin C is concentrated in the tear film to a higher level than that found in the blood.

Potassium: Probably the most important mineral for dry eye symptoms, potassium is usually very low in dry eye patients. This is usually linked to low intakes of folic acid, vitamin C and vitamin B6 along with high sugar consumption. You can take in at least 500 mg per day by increasing your consumption of fruits and vegetables (one banana contains 400 mg). [Source]

• To nourish the eyes, follow Popeye’s lead. Boil 4 ounces of fresh spinach in 4 cups of water. Drink that spinach tea every day to give essential sustenance to the eyes.
• Grape seed extract (OPC) and bilberry extracts comprise potent antioxidants for eye healthiness.
• Taking ginkgo every day has been shown to perfect circulation to the eyes. Discover it in a healthiness grocery store. [Source]

Theralife: Eye Enhanced (2 capsules)

First Evidence of Omega-3 EPA/DHA Effect on a Potential Root Cause of Dry Eye Syndrome Presented at the Cornea Society/EBAA Fall Educational Symposium