A new device for the early diagnosis of degenerative eye disorders

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Summary: Researchers have developed a new ophthalmological device capable of detecting degenerative visual problems such as age-related macular degeneration long before the first symptoms appear.

Source: EPFL

Researchers from an EPFL laboratory have developed an ophthalmological device that can diagnose certain degenerative eye diseases long before the first symptoms appear. In early clinical trials, the prototype was shown to produce images with a sufficient degree of accuracy in just five seconds.

The search for treatments to stop or limit the progression of degenerative eye disorders that can lead to blindness is advancing rapidly. But, at present, there is no device that can reliably diagnose these conditions before the first symptoms appear.

These disorders, the best known of which is age-related macular degeneration (AMD), involve changes in the photoreceptors of the eye. And they all have the same root cause: damage to the retinal pigment epithelium (RPE), a layer of cells that sits behind the photoreceptors.

The device developed at EPFL’s Laboratory for Applied Photonic Devices (LAPD) observes changes in RPE before symptoms appear, providing researchers with the first-ever in vivo images in which cells can be differentiated. Armed with this early detection capability, clinicians will be able to diagnose these disorders before irreversible symptoms appear.

The results of the first clinical trial have been published in a journal article Sciences of ophthalmology.

Observe changes in the cells behind the photoreceptors

In addition to causing AMD, deterioration of RPE causes a number of other eye disorders, including retinitis pigmentosa and diabetic retinopathy.

Located between the photoreceptors and the choroid (a thin layer of tissue containing vessels that transport blood to the retina), the RPE plays an important role in maintaining visual function and keeping rods and cones healthy. of the eye.

Several research groups have studied these cells under the microscope – in vitro – to determine their properties and observe the morphological changes that occur with aging but also with the onset and progression of retinal disorders such as AMD and retinitis pigmentosa.

Until now, however, there has been no easy and reliable method to observe RPE in a living patient – ​​in vivo – for the early detection and ongoing monitoring of these conditions.

Oblique light beams hold the key

Various attempts have been made to design a device that allows clinicians to examine the RPE. But so far, each has failed due to inadequate resolution, patient safety issues, or excessively long exposure times.

The EPFL team has developed a retinal camera with two oblique beams, aimed at the white of the eye, coupled with an adaptive optical system that corrects the distortions of the light waves to produce a sharp image.

This technology, called transscleral optical imaging, is similar to existing retinal imaging systems in its use of infrared light beams.

But, according to Christophe Moser, who heads the LAPD at the engineering school, there is one key difference: “The beams focus obliquely across the white of the eye, which circumvents the problem of excess light caused by highly reflective cone photoreceptor cells. , located in the center of the eye, when you illuminate the retina through the pupil.

Armed with this early detection capability, clinicians will be able to diagnose these disorders before irreversible symptoms appear. Image is in public domain

The light waves are then captured by the camera as they exit the eye through the pupil. The team had a eureka moment when they saw the first clear image on screen, as it was the first time anyone had observed this part of the human body using a camera. clinically compatible imaging.

A first clinical trial involving 29 participants

The researchers developed a clinical prototype in partnership with EarlySight, a spin-off from the same EPFL laboratory. With an exposure time of less than five seconds, a key speed advantage for potential diagnostic use, the camera is capable of capturing 100 raw images. The algorithms then align and regroup the raw footage to produce a single high quality image on screen.

The interface has five buttons, each corresponding to a predefined area of ​​the eye, allowing the desired image to be selected. Users can also click anywhere on the back of the eye diagram to select the specific area they wish to image.

The prototype device, known as Cellularis, was developed as part of the European Union’s EIT Health ASSESS project, in partnership with Francine Behar-Cohen’s research team at the National Institute of Health and of medical research (INSERM) in Paris, and with the clinical research laboratory center of the Jules-Gonin ophthalmological hospital in Lausanne.

The camera was then evaluated in a clinical trial led by Irmela Mantel, a physician associated with the retina medical unit of the Jules-Gonin ophthalmological hospital, designed to assess the device’s ability to produce images Clear RPE in 29 healthy volunteers. In each case, the images generated by the camera were precise enough to quantify the morphological characteristics of the participants’ RPE cells. They were stored in a database for future contribution to medical research.

“The morphology of these cells, which play an essential role in retinal function, is a strong indicator of their health,” explains Laura Kowalczuk, a scientist at EPFL and Jules-Gonin Eye Hospital, and lead author of the study. ‘article.

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“The ability to accurately detect RPE cells and observe the morphological changes that occur in them is vital for the early detection of degenerative retinal disorders and for monitoring the effectiveness of new treatments.”

About this Age-Related Macular Degeneration Research News

Author: Press office
Source: EPFL
Contact: Press Service – EPFL
Image: Image is in public domain

Original research: Free access.
“In Vivo Imaging of the Retinal Pigment Epithelium Using Transscleral Optical Imaging in Healthy Eyes” by Laura Kowalczuk et al. Sciences of ophthalmology


Summary

In Vivo Imaging of the Retinal Pigment Epithelium Using Transscleral Optical Imaging in Healthy Eyes

Objective

For imaging healthy retinal pigment epithelial (RPE) cells live using transscleral optical imaging (TOPI) and to analyze statistics of macular RPE cell characteristics as a function of age, axial length (AL), and eccentricity.

Design

Monocentric, exploratory, prospective and descriptive clinical study.

Speakers

49 eyes (AL: 24.03±0.93 mm; range: 21.88 – 26.7 mm) from 29 participants aged 21-70 years (37.1±13.3 years; 19 males, 10 females)

Methods

Retinal images, including ultra-widefield fundus photography and spectral-domain optical coherence tomography, AL and refractive error measurements were collected at baseline. For each eye, 6 high-resolution RPE images were acquired using TOPI at different locations, one of which was imaged 5 times to assess the repeatability of the method. Follow-up ophthalmologic examination was repeated 1-3 weeks after TOPI to assess safety. RPE images were analyzed with custom automated software to extract cellular parameters. Statistical analysis on selected high contrast images included calculation of the coefficient of variation (CoV) for each feature at each replicate, Spearman and Mann-Whitney tests to study the relationship between cell features and eye features and/or subject.

Main judgment criteria.

Characteristics of RPE cells such as density, area, center-to-center spacing, number of neighbors, circularity, elongation, solidity, and CoV boundary distance.

Results

Macular RPE cell features were extracted from TOPI images at an eccentricity of 1.6° to 16.3° relative to the fovea. For each characteristic, the average CoV was less than 4%. Spearman’s test showed a correlation in RPE cell characteristics. In the perifovea, the region in which images were selected for all participants, longer AL was significantly correlated with decreased RPE cell density (R Spearman, Rs = -0.746; ppp=0.036) and increase in cell surface (Rs=0.454; p=0.013). Lower, less symmetrical, more elongated and larger circular cells have been observed over 50 years.

conclusion

TOPI technology imaged RPE cells live with a repeatability of less than 4% for CoV and was used to analyze the influence of physiological factors on the morphometry of RPE cells in the perifoveum of healthy volunteers.

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