Effect of palmitoylethanolamide on visual field damage progression in normal tension glaucoma patients: results of an open-label six-month follow-up

The purpose of this study is to assess the effect of palmitoylethanolamide (PEA) oral administration on intraocular pressure (IOP) and visual field damage progression in normal-tension glaucoma (NTG) patients. Thirty-two consecutive patients affected by NTG were enrolled and randomized in a 1:1 ratio to receive PEA treatment (group A) or no treatment (group B). Group A patients took ultramicronized 300 mg PEA tablets two times per day for six months. Best-corrected visual acuity (BCVA), IOP, and visual field test were evaluated at baseline and at the end of the six-month followup. No significant differences in clinical parameters between the two groups were observed at baseline. At six months, group A patients showed significant IOP reduction (from 14.4 +/- 3.2mm Hg to 11.1 +/- 4.3mm Hg, p < 0.01). No statistically significant changes were seen in BCVA in either group. Visual field parameters significantly diminished in patients receiving PEA compared to baseline values (-7.65 +/- 6.55 dB vs. -4.55 +/- 5.31 dB, p < 0.001; 5.21 +/- 4.08 dB vs. 3.81 +/- 3.02 dB, p < 0.02; mean deviation [MD] and pattern standard deviation [PSD] respectively), while no significant changes were seen in group B. A generalized linear model demonstrated that the final IOP, MD, and PSD was affected only by the systemic PEA treatment (p < 0.01 each) and not affected by demographic or clinical characteristic between the groups. Hence, systemic administration of PEA reduces IOP and improves visual field indices in individuals affected by NTG. Neither ocular nor systemic side effects were recorded during the study period.