Genentech Inc. on Monday said the average patient with age-related macular degeneration who received its experimental drug Lucentis could read an additional seven letters of a reading chart, compared with a vision loss of 10.5 letters among those who received sham injections.

The favorable difference, amounting to about 17 letters, was seen in a one year-trial, whose results were presented by researchers at a medical meeting in Montreal.

Genentech has said that U.S. regulators would likely require its drug to show a difference - in favor of Lucentis - of 15 letters. Each line on a reading chart consists of five letters, so a 15-letter difference is equivalent to the difference in reading three lines of a reading chart.