Latanoprost is a prostaglandin analogue and we already know that anti-prostaglandin therapy is effective in vernal conjunctivitis in particular: http://www.ncbi.nlm.nih.gov/pubmed/3115287
One would expect some worsening of allergic conjunctivitis in patients treated with prostaglandin analogues for glaucoma but the evidence is not very convincing: http://www.ncbi.nlm.nih.gov/pubmed/11789860
However, ocular allergic reactions induced by prostaglandin analogues themselves are well-described in the literature: http://www.ncbi.nlm.nih.gov/pubmed/16750448
Bottom line: Prostaglandin analogue eye drops used in glaucoma do not help in allergic conjunctivitis and are possibly harmful.
Ocular antihistamines (eye drops) (click to enlarge the image)
Bono from U2 reveals he always wears sunglasses because of glaucoma for 20 years - Telegraph http://buff.ly/1wdtlWi
Image source: OpenClipArt.org.