Innovative Hand-Held OCT Probe Takes High-resolution Images of Children’s Retinas


Handheld Device with cellular resolutionResearchers and ophthalmologists from Duke University have presented a new option to examine children’s eyes in a new study entitled “In vivo cellular-resolution retinal imaging in infants and children using an ultracompact handheld probe” published in Nature Photonics.

The new handheld device is about the same size as a pack of cigarettes, weighs next to nothing and is capable of gathering detailed information about the retina’s cellular structure.

The device is being hailed as a great achievement as up to now it has been very difficult to gather data as to how a child’s retina develops, as it matures by the age of 10. This has severely impacted and limited knowledge of how diseases affect a child’s vision early in life and has made diagnosing various diseases more difficult.

The human eye presents an extraordinary opportunity for research and imaging because it is easy to access; it is relatively self-contained; improvements in function can be easily measured, and there is even a natural opening that allows us to peer inside. The eye is also delicate though, with complex vital structures concealed mere millimetres below various surfaces, which necessitates the use of a wide range of technologies to study it.

There have been many tools and technologies designed to study the eye over the past few decades, the most popular of these being Optical Coherence Tomography (OCT), which works by shining specific frequencies of light into the tissues of the eye and comparing the reflections to identical but unimpeded light waves, allowing researchers to build 3-D images of the back of the eye that are several millimetres deep .

The problem with the equipment so far though has been that it has been bulky, big, heavy and time-consuming, which is never a good idea with toddlers.

Cynthia Toth, Professor of Ophthalmology and Biomedical Engineering at Duke University said:

Diagnostic tools that examine and image the retina have been well-designed for adults, but are exceedingly difficult to use in infants and young children who can’t hold the required position or focus for long enough periods of time. Before now, it hasn’t been possible to measure the impact of injury or diseases on their photoreceptors, the cells in the eye in which light is first converted into nerve signals.

Leukocoria (white pupillary reflex) caused by retinoblastoma. The tumor can be seen in the vitreous. There are seeds in the anterior chamber, anterior to the iris.

Leukocoria (white pupillary reflex) caused by retinoblastoma. The tumor can be seen in the vitreous. There are seeds in the anterior chamber, anterior to the iris.

This is great news as it could shed a lot of light on hereditary paediatric retinoblastoma, which  is the most common intraocular cancer found in children. Retinoblastoma was the first cancer to be directly associated with a genetic abnormality, and it can occur sporadically or it can be inherited.

Retinoblastoma occurs in 1 in 18,000 to 30,000 live births worldwide. and it has been the subject of great interest because of its well-studied genetic inheritance pattern and molecular biology.

A new type of smaller scanning mirror recently reached a point where it could replace larger, older models. A new design using converging rather than collimated light cut the telescoping length of the device by a third.

Custom lenses detailing curvature, thickness and glass type were designed by first author Francesco LaRocca and specially fabricated.

A mechanical design to hold and integrate the components was designed by Derek Nankivil — who, like LaRocca, recently graduated with a PhD from Duke — and fabricated in a machine shop on Duke’s campus.

The new device was then given to clinicians for testing on adults, which proved that it was capable of getting accurate photo-receptor density information. It was also used for research imaging in children who were already having an eye exam under anaesthesia.

According to the developers, it …”was able to quantify packing densities of parafoveal cone photo-receptors and visualize cross-sectional photo-receptor substructure in children ranging from 14 months to 12 years.

An image of a retina taken with the new handheld probe. The tiny white dots are photoreceptors called cones, which were not visible with previous handheld technologies. The concentrated circular area is called the fovea. It is believed that, as the eye matures, photoreceptors migrate to this area, making it much more densely populated than others. Credit: Photo credit: Photo by Joseph Izatt, Duke University.

An image of a retina taken with the new handheld probe. The tiny white dots are photoreceptors called cones, which were not visible with previous handheld technologies. The concentrated circular area is called the fovea. It is believed that, as the eye matures, photoreceptors migrate to this area, making it much more densely populated than others. Credit: Photo credit: Photo by Joseph Izatt, Duke University.

The new hand-held probe is based on OCT and other technologies, features a compact optical design weighing a mere 94 grams. It allows researchers to gather structural information about the eyes of infants and toddlers for the first time.

But because children have never been imaged with these systems before, there’s no gold standard that we can compare it to,” said LaRocca. “The results do, however, match theories of how cones migrate as the eye matures.

The tests also showed different microscopic pathological structures that are not normally possible to see with current lower-resolution clinical-grade handheld systems.”

The prototype is being used by clinicians at Duke Health, which means that the amount of information being gained from children’s scans could eventually create a database to give a much better picture of how the retina matures with age.

Joseph Izatt, the Michael J. Fitzpatrick Professor of Engineering at Duke and a pioneer of OCT technology said:

This paper demonstrates the first time researchers have been able to directly measure the density of photoreceptors called cones in infants. As such, it opens the door to new research that will be key in future diagnosis and care of hereditary diseases.

The group is already working on the next generation of the design after getting feedback from clinicians on what can be improved.

 

 

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This is a blog about CHILDHOOD CANCER and CHILDHOOD CANCER AWARENESS Little Fighters Cancer Trust is a non-profit organisation that offers support and aid to Children with Cancer and their families. When a child is diagnosed with cancer it affects the whole family. One of the parents, usually the mother, must give up their job to care for the child and this creates financial problems for the family. In South Africa especially the majority of these families are not well-to-do; many of them are rural. A diagnosis of cancer can wipe out any family’s finances, let alone a poor family. The costs of special medications, special diets, hospital stays, transport to and from the hospital or clinic and accommodation and food costs for the mother who spends most of the time at her child’s bedside are astronomical. These are the people and problems that fall through the cracks, and these are the people that Little Fighters Cancer Trust has pledged to help in any way possible. LFCT takes a holistic approach to assisting the Children with Cancer and their Families, with the main aim to be the preservation of individual dignity and pride. Little Fighters Cancer Trust also focuses on promotion and advocacy of National Childhood Cancer Awareness in an effort to increase awareness of Early Warning Signs of Childhood Cancer. This would result in earlier diagnosis, giving the Child with Cancer more of a chance at Treatment and Survival. See "About" for more Background info

Posted on 15 August, 2016, in Blog, Research and tagged , , , , , . Bookmark the permalink. Leave a comment.

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