Modulation of tear film protein secretion with phosphodiesterase inhibitors

A double-blind randomized clinical study was conducted to determine whether nicardipine hydrochloride was a useful treatment for dry eye. We examined its effect on the tear film, ocular surface and ocular comfort. Nicardipine hydrochloride, 3-isobutyl-1-methylxanthine and pilocarpine hydrochloride w ere dissolved in an artificial tear vehicle and applied topically to one ey e of 12 subjects on separate days. Ocular physiology, ocular comfort and te ar volume were assessed. The trial was repeated with nicardipine in an aque ous gel vehicle. Tears were collected and assessed for protein concentratio n and protein profile, using electrophoresis and mass spectrometry. Nicardi pine induced conjunctival redness and symptoms of dryness and irritation. T here was no change in total tear protein concentration or volume. An increa se in a 68 kDa protein was observed, this was probably due to conjunctival vessel dilation and leakage of albumin. The adverse symptomatology and incr eased conjunctival redness experienced with nicardipine make it an undesira ble treatment for dry eye.