When 32-year-old Megan Santos of Riverview, Fla., noticed that one of her baby daughter's eyes was a slightly different color than the other, her intuition told her that something was wrong.
Concerned, Santos posted a picture of 1-year-old Rowan Santos on the online pregnancy community BabyFit.com, of which she is a member. The picture clearly showed a hazy, white glow in Rowan's left eye -- an atypical reflection of the camera flash not seen in the infant's other eye.
She soon received a message from Madeleine Robb, another 32-year-old mother living in Stretford, the United Kingdom, encouraging her to ask her doctor about a rare but serious cancer that can bring about such a color difference.
Santos followed Robb's advice. And as it turned out, Santos' post may have well saved her child's life.
"After I put the picture up, she saw it, and she sent me a private e-mail in which she said that Rowan might have retinoblastoma in her left eye," Santos said. "She said, 'Not to worry you, but I think you should look at this Web site.'"
The Web site detailed the condition known as retinoblastoma -- a potentially deadly form of childhood cancer that can affect one or both eyes. Immediately, Santos contacted her doctor. She saw him the next day, on the morning of Aug. 8, and he, in turn, referred her to ophthalmology and cancer specialists.
A battery of scans and other tests revealed that Rowan did, in fact, have a cancerous tumor growing on the retina of her left eye.
"Her prognosis is good, as far as the doctor can tell," Santos said. "[The cancer] had not yet reached her optic nerve, which would have then brought it directly to her brain."
But with the favorable prognosis for survival came devastating news.
"She is going to lose her eye," Santos said. "That's a definite."
Doctors plan to treat the tumor by burning away the cancerous tissue with a laser. Rowan will undergo four rounds of chemotherapy, followed by surgery to remove her eye and the tumor, and then three more rounds of chemotherapy. The surgery to remove Rowan's left eye will be in November or December.
Still, Santos is thankful that the cancer was detected early enough to save her daughter's life. And ophthalmic experts said that her quick action was crucial in ensuring her daughter's survival.
"She probably saved her child's life," said Dr. Susan Taub, assistant professor of ophthalmology at Northwestern University in Chicago. "An ounce of caution is worth a pound of cure. This tumor kills children."
Retinoblastoma is a cancer that strikes children as late as age 5, though it may start even in the womb. It arises from the cells of the retina, the spot of nerves at the back of the eye that captures light and sends vision signals to the brain.
Dr. Linn Murphree, director of ocular oncology at the Children's Hospital Los Angeles' Retinoblastoma Center, said the cancer is an exceedingly rare one, affecting only about 1 in 15,000 babies every year.
"There are probably only 300 new cases a year in all of North America," Murphree said.
But while the disease is rare, it is also ruthless. Worldwide, 87 percent of children stricken with retinoblastoma die. Survival is best in developed countries, but even among the children who have the disease in these nations, 97 percent suffer moderate to severe visual impairment as a result.
"Most of these cases involve the removal of one eye at least," Murphree noted. "Obviously, for young parents who face a diagnosis of a cancer in their child that is both life-threatening and vision-threatening is very difficult."
The other characteristic of the cancer that makes it so dangerous is the fact that it is very difficult to detect. Santos, like most other parents, had taken her baby girl to all of her recommended checkups, the most recent one at 9 months. While the cancer was most likely present in Rowan's eye at this time, even the pediatrician missed it.
Murphree said the test that would best reveal whether or not a child indeed had retinoblastoma would involve dilating the eye with eye drops -- a test that is not currently a standard practice among pediatricians. Years ago, Murphree spearheaded an effort to make these tests routine. But because the disease is so rare, most doctors remain opposed.
"The problem is that pediatricians will see one case of retinoblastoma in 30 years of practice," he said. "You would have to do [the test] in 15,000 healthy babies before you find it in one."
But as in the case of Rowan Santos, another means to detect signs of retinoblastoma and other eye problems in infants may be as close as the family camera.
"The 'red eye' look that the public dislikes is the tell-tale sign of a healthy eye," Taub said. "The lack of it is the clue there is something wrong."
In fact, Taub said she and her fellow ophthalmologists regularly ask families to bring in photos: "We call it F.A.T. -- family album tomography."
"The flash camera can be used usefully for home diagnosis of infant and child problems," said Seattle ophthalmologist Dr. Richard Bensinger.
"If in a series of photos, the same eye always is red and the other dark for your child, then the dark eye may be always turned away from the central axis and might be crossed," Bensinger said. "This could be due to ordinary misalignment, which can be fixed, or due to something inside the eye blocking normal vision, such as a tumor, or cataract, or other internal obstruction, which needs attention right away."
Vigilance is especially important for parents with a family history of the disease.
"Those with a family history should be very alert," said Dr. Harry Quigley, director of the Dana Center for Preventive Ophthalmology at the Johns Hopkins University's Wilmer Institute in Baltimore. "An eye deviating to the side compared to the other eye after age 3 to 4 months should be examined by an ophthalmologist."
Quigley added that infants who rub their eyes regularly or who have severe redness in their eyes should also be checked out.
But for Santos, one of the most important steps turned out to be sharing her concerns in a supportive online community. Phone messages left with Robb were not immediately returned. But Santos said that the U.K. mother continues to offer support as Rowan, who turned 1 on Aug. 20, faces the months of treatment ahead.
"I love her," Santos said of Robb. "She was very brave to send the e-mail she did because cancer is a very scary thing to have to tell someone about."
"She is an amazing woman. I will always be grateful to her, and my family will always be grateful."
ABC News information specialist Brad Martin contributed to this report.