What your eye can reveal about your health

by ANGELA EPSTEIN, Daily Mail

A simple eye test can do more than assess your sight. It could save your life. Warning signs for a range of life-threatening illnesses can be detected in the inner workings of the eye. So a trip to the optician could save more than your sight.

Diabetes

Dramatic and unexpected changes to the prescription of your glasses could be an early sign of diabetes. Blurred vision is usually caused by glucose seeping into the lens and changing its shape, making it difficult to focus. A further eye test is recommended once blood sugar has been regulated.

Another complication of diabetes is diabetic retinopathy, which causes the blood vessels in the retina to become weak, blocked and to haemorrhage.

Examination with an opthalmoscope would see white crystal-like patches on the retina or splashes of blood. There are no obvious symptoms of Type II diabetes (when the body produces some but not enough insulin), so early diagnosis is crucial to avoid long-term and sometimes fatal complications.

Eye tumours

Malignant melanoma of the eye is an aggressive cancer which affects the choroid layer between the retina and the whites of the eye. Through an opthalmoscope, a melanoma would look like a large, raised surface or mole on the pigment layer of the retina.

Melanomas can spread rapidly, particularly along the optic nerve to the brain, so early diagnosis is crucial. It can be caused by excessive exposure to sunlight.

Hypertension

A quarter of adults who suffer from high blood pressure (hyper-tension) are unaware they have the condition. Yet if left untreated, it can cause heart attacks or strokes.

An eye test will reveal crossings in the blood vessels of the eye, where the artery has hardened and nipped the vein underneath. Very high pressure will cause blood vessels to burst and haemorrhages to form. Opticians look for signs of high blood pressure in anyone over 30.

Strokes

Bleeding from, or blood clotting in, a cerebral artery causes strokes, which can be detected through a field vision eye test. Sudden difficulty seeing in one or both eyes can be the sign of a stroke. The test reveals whether part of the all-round sight is damaged or missing, usually correlating with the side of the brain affected by the stroke.

Visual defects are strongly linked with the onset of multiple sclerosis (MS). These are usually intermittent blurring or even blacking out of vision, as well as difficulty in focusing.

MS can often be detected clearly through field vision analysis during an eye test. The disease causes inflammation of the optic nerve - optic neuritis - which creates a banana- shaped field defect called a scotoma just below the macula of the eye, which is specific to MS.

FETAL GENOME SEQUENCING COULD SPOT DISORDERS

Researchers have mapped the genome of a fetus using DNA samples from parents.
A test based on the new technique could detect the roughly 3,000 conditions known as Mendelian disorders.
The hope is that researchers can develop a clinical test that detects many diseases noninvasively.

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At present, the only test routinely done that uses maternal blood plasma. Click to enlarge this image.
Corbis

In a development scientists are calling a "tour de force," researchers have reconstructed the genome of a fetus using DNA samples from the parents.

Because their technique did not require an invasive test to take samples from the fetus itself, it's an important step toward what could become a low-risk way to identify genetic disorders early in development, experts say.

Currently, "when genetic testing is done, it's done for just a few diseases," said lead author Dr. Jay Shendure, an associate professor of genome sciences at the University of Washington.

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A test based on the new technique could detect the roughly 3,000 conditions known as Mendelian disorders, each of which are the result of a single mutated gene, Shendure said. Huntington's disease, hemophilia andsickle-cell anemia fall into this category.

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While each of these disorders is relatively rare, together they affect about 1 percent of births, Shendure said.

"This is amazing," said Dr. Ada Hamosh, director of the Institute of Genetic Medicine at the Johns Hopkins University School of Medicine, of the findings. "On the other hand, in no way is this ready for prime time," said Hamosh, who was not involved with the research.

Shendure and colleagues put together the fetal genome using a saliva sample from the father, and a sample of blood plasma from the mother. About 13 percent of the DNA found outside of cells in a pregnant woman's body belongs to her fetus.

They sequenced the regions of DNA they were aiming for with 98.2 percent accuracy, as confirmed after the baby's birth with a test on blood taken from the umbilical cord blood.

Shendure estimated that reconstructing the fetal genome cost roughly between $20,000 and $50,000.

But with the cost of genome sequencing expected to come down, and as the technique is further refined, Shendure said, the hope is that researchers can develop a clinical test that detects many diseases noninvasively.

It's also hoped that testing could be done earlier in pregnancy than current tests, he said. In the study, the researchers sequenced the fetal genome twice, once in a fetus at 8 weeks into the pregnancy, and another time with a different fetus at 18 weeks. The highly accurate information only came at the later time.

The accuracy is affected variations between pregnancies, Shendure noted. "It's possible it could be done in the first trimester, it just may require more resources to do it."

At present, the only test routinely done that uses maternal blood plasma, as in the study, is for Down syndrome .

But to confirm the results of that blood test, an invasive test called amniocentesis, which requires fetal tissue samples, is used, said Dr. Laird Jackson, a professor of obstetrics and gynecology at the Drexel University School of Medicine.

Hamosh said that while a noninvasive test would be an improvement, at present, a full analysis of a fetus's genome would be overkill, because parents can be tested for specific genes of concern, and a fetus could be tested if the parents' tests reveal a potential problem.

"You don't need whole genome sequence information on a fetus," she said. If a family is known to carry a risky version of a gene, then a test for that gene can be done.

But as the techniques used in the study are improved, she said, they could be helpful in catching cases where new mutations arising in the fetus are the source of genetic diseases, rather than mutations inherited from the parents.

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"I think this paper is a tour de force," Hamosh said. "This was unthinkable six months ago. Is it ready for any kind of clinical application? Not at all yet."

While a noninvasive test may be at least several years from the clinic, Jackson said, ultimately they could be a boon for parents, providing more of them with more information about their future children.

With current invasive tests, "if you go to the right person, if you go to a center that has excellent [health professionals], the risk of losing that pregnancy is so small," Jackson said.

But many mothers can’t get to those top-notch facilities, he said.

A noninvasive diagnostic test could increase access, Jackson said. "Now mommy only has to go some place where someone can draw her blood."

Pass it on: Scientists have successfully sequenced the genome of a developing fetus without needing an invasive test.

Why belly fat isn’t all bad

A fatty membrane in the belly called the omentum has until recently been considered somewhat like the appendix – it didn’t seem to actually serve much purpose. But Loyola University Chicago Stritch School of Medicine researchers have found that the omentum appears to play an important role in regulating the immune system.

The finding could lead to new drugs for organ transplant patients and patients with auto-immune diseases such as lupus and Crohn’s disease.

“We now have evidence that the omentum is not just fat sitting in the belly,” said Makio Iwashima, PhD, corresponding author of a study published in PLoS ONE.

Iwashima is an associate professor in the Department of Microbiology and Immunology at the Loyola University.

The omentum is a membrane that lines the abdominal cavity and covers most abdominal organs.

It is a repository for fat tissue. A research team headed by Iwashima and Robert Love, a world renowned lung transplant surgeon, examined the effect that mouse omentum cells had on T lymphocyte cells from a mouse.

T cells are the immune system’s first line of defence against infection. They identify, attack and destroy bacteria, viruses and other infectious agents. Normally, T cells multiply in response to an infectious agent, such as an antibody.

An illustration of t-cells deployed during a viral infection in the blood stream

But when researchers put omentum cells in with activated T cells that had been exposed to antibodies, the T cells did not multiply as they normally would, but instead died. The omentum cells had this effect only on T cells that had been activated. Omentum cells did not have any effect on inactive T cells.

It appears that omentum cells secrete a substance that tamps down the immune system.

This discovery could lead to new drugs that would suppress the immune system with fewer side effects than those caused by immune-suppressing drugs now in use. Such drugs could be used, for example, to suppress the immune system in a patient who has received a lung transplant.

In addition to modulating the immune system, the omentum also appears to play a critical role in regenerating damaged tissues, according to Iwashima.

The omentum contains mesenchymal stem cells that migrate to the site of an injury and help regenerate tissue. Mesenchymal stem cells are cells that have the ability to develop into various types of specialised cells.

In this study, researchers showed that, in tissue-culture flasks, omentum cells can
differentiate into lung-type cells as well as bone cells.

Iwashima believes that the omentum may be organ specified for tissue healing and cell regeneration.