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March 27 (Reuters) - Ohr Pharmaceutical Inc said its experimental eye drug failed the main goal in a mid-stage study as a combination therapy, sending the company's shares plunging 64 percent in premarket trading on Friday.

The study tested the eye-drop solution, OHR-102, in combination with Roche Holding AG's injectable eye drug Lucentis, in patients with the wet age-related macular degeneration (AMD), the leading cause of blindness in the elderly.

Ohr's drug failed the study's main goal of reducing the average number of Lucentis injections per patient when used in combination with the Roche drug.

Wet AMD is characterized by the growth of new blood vessels under the retina and macula, a process known as choroidal neovascularization or CNV that leads to a rapid deterioration in vision.

There are two forms of CNV, "classic" and "occult". The "classic" version of the condition is the most severe and affects about two-thirds of wet-AMD sufferers.

Although a combination of OHR-102 and Lucentis improved visual clarity in about 42 percent of classic CNV patients, compared with 28 percent in the Lucentis monotherapy group, less of a benefit was seen in the overall population, the company said.

Existing FDA-approved treatments for wet AMD, which include Regeneron Pharmaceuticals blockbuster eye drug Eylea, are injected directly into the eye, while Ohr's solution is designed for self-administration.

Ohr's shares were down 63 percent at $3.15 in premarket trading. Up to Thursday's close, the stock had risen about 5 percent this year.

(Reporting by Natalie Grover in Bengaluru; Editing by Simon Jennings)