The eyes have it. At least in the photographs of Eugene Richards they do, more than any other feature; they're what draw you into his depictions of life "below the line", as his 1987 book subtitled 'Living Poor in America' termed his milieu of choice.

But more than that, they tell you about the man behind, in front of and sometimes even obscuring the camera, as in his photograph of Cuban refugees, in which not even Richards's bald, gaunt silhouette can dull the intense gleam of the whites of their nervous, exhausted eyes. They show he's no fly on the wall, that he has earned his right to be there.

Richards flashed into being in 1944 in Dorchester, Massachusetts, in an Irish, German, Polish and Puerto Rican community, his father a shipyard painter, his mother a house-cleaner. After studying English and journalism, he trained in photography with Minor White, the renowned force behind Aperture, the photography institution and magazine.

In the beginning - for Richards - was the deed. Then came the photograph and finally the word. And the word was Vietnam. Having protested against this war - "I don't know about other wars. But this war is shit" - he joined VISTA (Volunteers in Service to America), only to be cast out for what some saw as dissident ways. He worked as a health worker in the Mississippi Delta, Arkansas and then, with some stragglers from VISTA, co-founded RESPECT, an organisation which distributed food and clothing to the impoverished, helped organise poor black people and published a newspaper - which, incidentally needed photographs.

Richards has spoken with great pleasure of that time in the delta when he could just walk into peoples' houses without knocking, something alien to his upbringing. "It made me feel alive. I grew up in an Irish neighbourhood and the doors were always locked."

Besides that obvious connection to Ireland, this exhibition is timely and important for Dublin. It has become too easy to pass by the homeless, avoiding their stares, if, indeed they are capable of holding one, their diseased skin and sometimes drugged-out demeanour marking them as "other".

Walk into this exhibition, however, and that's not an option. Something in the faces of the poor - and the perspectives which denote familiarity - show that Richards is not an outsider, not a voyeur.

But if that term must be used, "a voyeur with a purpose" is how he describes his intrusions.

Of course, some of the eyes in his pictures don't see - they are merely frames within a frame. Like the old man with river blindness on the banks of the Niger, the little girl with firmly shut eyes, holding forth a doll's head with an open stare, or the dilated, yet infinitely expressive pupils in Shooting cocaine, Brooklyn, 1988.

Below the line? Crossing the line more like it. If many of his subjects are indeed "below the line", then he, as a photojournalist, shows that you have to cross it to find the truth.

One might think that documenting such lives risks turning the plight of individuals into a generality.

But if so, then this is only a by-product of Richards's chief aim, which is to be specific. And as a man of stoic integrity, he has time and again applied this ethic to his own personal life, first in Dorchester Days and then in a book documenting the struggle of his wife, Dorothea, against breast cancer, which one publisher approached by Richards referred to as "disgusting".

It's the age-old story: the genotype of the specific life - with a name, a family, and pain - is conjured into being through some mysterious transgenic factor of audience perception which renders the picture allegorical. But that doesn't mean he's setting out to turn anyone into a poster-child for poverty.

Richards's tendency to take us where we would not normally go may arise from the fact that he is, in a way, stuck in a place he himself can't escape from. "I never got over growing up in Dorchester, \," he has said. "There was always an edginess, sort of a cultural questioning. You didn't quite trust the Jews, you didn't quite trust the Puerto Ricans, the blacks, the Italians. Growing up Irish, you always heard this stuff from the adults, and it was very discomforting. I never had a clue when I was a kid why I should have a problem with anyone. I think it was the beginning of my social interest of wanting to find out for myself, partially because I grew up exposed to all the bigotries that I didn't want to have."

E.R. are the perfect initials for a man whose experience of and subsequent book portraying emergency room medicine (The Knife and Gun Club, 1989) shows such a devotion to the individuals involved, that he lists them as his very own "Cast of Characters".

It is only his later confession that "all the time I was there I would have given anything to be able to save a human life", that hides the dilemma of the ever-present inadequacy felt by a journalist next to the extraordinary lives he routinely witnesses.

This fact is cast into stark relief when that journalist then becomes a star, a quality inevitable for a man who, over the years, has been a member of Magnum, received National Endowment for the Arts awards and grants, and titles such as Photojournalist of the Year.

The teachers' resource pack prepared by the Gallery of Photography for educational purposes has been somewhat sanitised, with photographs of gay fathers and their infant child, as well as discussions of drug use in the Appalachians removed from the source article so as not to cause offence.

The only lesson this seems to reinforce is that while voyeurism may at times be necessary, so is censorship. One can only hope that curious, astute children will ask why it is that while Richards seems comfortable snapping the filth, degradation and grime of the projects, his subject matter, as presented to them, doesn't extend to tender moments of individuals living alternative lifestyles.

In his early work - there are now 11 books - Richards didn't take a writer with him on assignments; instead, he let the photographs, and perhaps the transcribed stories of his new acquaintances do the talking. A characteristic reflected in Classroom, Uganda, 1991, in which children and adults surround a tree graffitied with a crude alphabet, that appears to say that although people are making an effort, sometimes, often, it all comes to nothing. With words, you can say a junkie is a junkie - or skim read and all will be fine.

However, writing has become increasingly integral to his work, perhaps to tell what photographs can't, possibly even signalling a loss of faith in photography.

But it must be noted that Richards has never relied solely on the photograph as a medium for social change without supporting his cause with either action or words. After all, social change must be tackled on all fronts.

And now, add to the word and the image the film. Broadening out from still black and white photography, Richards has made two films, the most recent of which, But, the day came, about his own mother's decline, has its Irish premiere at Dublin's Doclands International Film Festival later this month, where the artist will be present.

If there is something in the famous Godardism that, "photography is truth. And cinema is truth 24 frames a second", then expect to be moved.

Eugene Richards's exhibition runs at the Gallery of Photography, Temple Bar, Dublin, until October 6th. He will present an illustrated talk on his work on Wednesday September 26th, at 5 p.m. in the Irish Film Centre (IFC), Dublin. His film, But the day came, will be screened at the Doclands documentary film festival in the IFC on Friday September 28th at 5 p.m. The festival runs from September 27th-30th. Further information from: 01-6708177 and info@doclands.ie