This is rather an interesting study and since the full text is available free you can easily review the details. They compared a group who took Tears Again Hydrate (flaxseed and evening primrose oil supplement sold on prescription) for six months with a group who took that AND took Restasis for the last 3 months of the 6 month period. In this study it didn't appear that Restasis added much.

Efficacy of a new prescription-only medical food supplement in alleviating signs and symptoms of dry eye, with or without concomitant cyclosporine A.

PURPOSE:
To evaluate the effect of a new, prescription-only medical food supplement containing omega-3 and omega-6 essential fatty acids on dry eye signs and symptoms, with or without concomitant topical cyclosporine.

METHODS:
A total of 43 subjects were randomized and followed for 6 months. Group 1 (n = 23) was assigned to take two soft geltabs of the medical food supplement by mouth twice daily for 6 months. Group 2 (n = 20) was directed to take the medical food supplement in the same manner, along with topical cyclosporine, instilled twice daily during the last 3 months of the study. Subjects were evaluated at baseline, month 1, month 3, and month 6. Primary outcome measures included tear breakup time (TBUT), conjunctival staining, corneal staining, and change in subjective symptoms.

RESULTS:
Both groups had a statistically significant improvement in TBUT between baseline and month 6. In the food supplement only group, TBUT improved by 0.805 seconds from baseline to month 6. In the supplement/cyclosporine group, TBUT improved by 1.007 seconds from baseline. There was no statistically significant difference in TBUT between the two groups at baseline, month 3, or month 6. There were no significant differences in corneal or conjunctival staining between or within groups. Subjective symptoms were also improved in both groups.

CONCLUSION:
Supplementation with the proper balance of omega-3 and omega-6 essential fatty acids improved TBUT and relieved patient symptoms. The addition of topical cyclosporine did not convey any statistically significant improvement in TBUT beyond that achieved by the supplement.
Clin Ophthalmol. 2011;5:1201-6. Epub 2011 Aug 25.
Jackson MA, Burrell K, Gaddie IB, Richardson SD.
Source
Jacksoneye, Lake Villa, IL, USA.