Late in his life, French impressionist Claude Monet, who died in 1926, produced a series of paintings most notable for the fact that they were very, very blue.

He may have been trying to make an artistic statement, or capture a particular mood. Or the reason the canvases were blue could have been because that was the only color Monet could see.

Dr. James Ravin, an ophthalmologist with an undergraduate degree in art history, has spent five years studying how Monet`s failing eyesight and visual difficulties affected his later work. He has consulted Monet`s letters to his eye surgeon, talked with art historians and examined a pair of Monet`s glasses.

In an article published in the Journal of the American Medical Association, Ravin discusses this influence on an acknowledged leader of the impressionist movement.

''The cataracts that blinded Monet were an important influence on the way he saw the world and the way he painted it,'' the article concludes.

Monet`s visual difficulties first became apparent when he was in his 60s, Ravin says, when his loose impressionist style began to blur even further. By 1918, Monet wrote a note to a Paris eye doctor to complain of the change.

''I no longer perceived colors with the same intensity,'' he wrote, ''I no longer painted light with the same accuracy. Reds appeared muddy to me, pinks insipid, and the intermediate and lower tones escaped me.''

Monet soon was forced to label tubes of paint in order to distinguish colors, in 1922 blues had disappeared from his paintings in favor of red and yellow. That year he was pronounced blind, and was encouraged to undergo cataract surgery.

A long convalescence followed the surgery, because techniques were not nearly as sophisticated as they are today.

Monet noticed a dramatic change after the operation. The cataracts, which had formed a yellow-brown filter on his right eye, had been removed and now

''Monet was able to see colors he had not seen for years, particularly violet and blue tones.''

Ravin explains that similar to a person who has been in darkness for a long time and then goes out into the sun, Monet saw the new colors as brighter than they were.

''I see blue,'' Monet told his physician in 1924, a year and a half after he had cataracts removed from his right eye. ''I no longer see red or yellow. This annoys me terribly, because I know these colors exist.

''It`s filthy. It`s disgusting. I see nothing but blue.''

Monet was not pleased with the blue paintings he created during this period, Ravin says, and wanted to destroy them. Monet eventually overcame the color difficulties by using glasses with tinted lenses, and lived to finish a major series of paintings for the French government.

The blurred paintings Monet created as his eyes deteriorated were not highly thought of at the time, Ravin says, but are now seen as a link to 20th Century abstract art.

He admits this interpretation might not sit too well with those who study art for art`s sake.

''When you talk about art historians evaluating this, they don`t know quite what to do,'' Ravin says.

And indeed, Richard Brettell, curator of European Paintings and Sculptures for the Art Institute in Chicago, says, ''No one historically has dealt with this very much. I think art historians would have a tendency to resist this type of explanation.''