Two distinct eye diseases may contribute to common blinding eye condition AMD

Summary: A study demonstrates two different types of deposits in the retina that appear to contribute to age-related macular degeneration.

Source: Mount Sinai Hospital

Two separate eye diseases may contribute to age-related macular degeneration (AMD), one of the leading causes of blindness in the United States, according to a new study from the New York Eye and Ear Infirmary of Mount Sinai.

The research, published January 9 in Eye is the first to demonstrate that two different types of deposits in the retina can contribute to early AMD, which can progress to advanced AMD and blindness.

These two diseases could be diagnosed, studied and treated separately with appropriate early intervention to prevent vision loss and other complications.

According to the Centers for Disease Control and Prevention.

AMD in its early form is currently considered a unique disease with deposits containing cholesterol. These deposits are known as subretinal drusen and drusenoid (SDD) deposits.

Early AMD can progress to blindness in two advanced forms, commonly referred to as wet and dry AMD. The advanced dry form is also called geographic atrophy (GA) by ophthalmologists.

“An amazing fact is that the retina can generate fluorescent light, similar to that of a light fixture, but a million times dimmer.

“For the first time, we were able to measure this faint light, called autofluorescence (AF), with ultra-sensitive detectors to study advanced AMD.

“We found that it was consistently twice as bright in patients with SDD as in those with drusen when they reached advanced AMD, and came from a single diseased layer,” says lead author R. Theodore Smith, MD, Ph.D., Professor of Ophthalmology at the Icahn School of Medicine at Mount Sinai.

“Combined with our previous research, this provides conclusive evidence that two different disease processes in AMD are taking place, one with darker fluorescence and drusen, and one with brighter fluorescence and SDS, and they should be treated differently.”

Drusen formation can be slowed down with appropriate vitamin supplements to prevent vision loss. Currently, there is no known treatment for SDD, and they pose a greater threat of advanced AMD.

However, in a recent previous study, Dr. Smith and a team of Mount Sinai researchers found that patients with SDD are likely to have heart damage from heart failure and heart attacks, or valve disease. advanced heart disease, or strokes associated with carotid artery disease.

“We believe that SDD results from impaired blood flow to the eye caused by these vascular diseases. We therefore believe that patients with SDD should be warned that they may have life-threatening undetected heart disease that should be assessed and processed.

“Further research needs to be conducted on women and disadvantaged groups where neglected heart disease is a serious problem. Eye scans for SDD and routine cholesterol blood tests could solve this problem. Additionally, treating cardiovascular disease and restoring blood supply to the eye can also help SDD.

This work should prompt retinal specialists to look for both drusen and SDD with optical coherence tomography (OCT), a standard retinal imaging technique, to better counsel patients.

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These two diseases could be diagnosed, studied and treated separately with appropriate early intervention to prevent vision loss and other complications. Image is in public domain

The new research measured autofluorescence and assessed OCT scans in 18 patients (32 eyes) with advanced AMD and geographic atrophy (GA). Since GA can occur in multiple regions of the retina, the researchers analyzed a total of 52 GA regions.

They also selected only patients who had undergone OCT scans in the previous three years so they could determine whether the diseased regions started with drusen, SDD or both. 18 of these regions were from drusen, 12 were from SDD, and 22 were from mixtures of drusen and SDD.

The team then measured the brightness of the fluorescent light coming from these regions with a highly sensitive light meter. They found that it was twice as bright in patients with SDD as in those with drusen. Specifically, brightness readings averaged 72 in SDD subjects and 36 in Drusen subjects, with the mixed group’s values ​​falling in between.

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“All of these numbers translate into one fundamental fact: there are two different diseases in AMD, one with drusen and one with SDD,” says Dr. Smith.

“The good news for patients and ophthalmologists is that in the clinic, we won’t need advanced AF measurements to know what form of AMD the patient has. As our research has shown, both forms are associated with drusen and SDD, and these deposits can be identified by standard retinal imaging. It therefore becomes important to diagnose the patient’s form of AMD for the treatment and prevention of the disease. »

About this Age-Related Macular Degeneration Research News

Author: Press office
Source: Mount Sinai Hospital
Contact: Press Office – Mount Sinai Hospital
Picture: Image is in public domain

Original research: Access closed.
“Two potentially distinct pathways to geographic atrophy in age-related macular degeneration characterized by quantitative fundus autofluorescence” by Wei Wei et al. Eye


Summary

Two potentially distinct pathways to geographic atrophy in age-related macular degeneration characterized by quantitative fundus autofluorescence

Context/Objectives

Demonstrate two distinct pathways to geographic atrophy (GA) that originate from epithelial drusen/soft pigment detachments (PEDs) and subretinal drusenoid deposits (SDDs), respectively, and are characterized by their endpoint quantitative autofluorescence (qAF) levels ).

Methods

23 eyes of 18 patients with GA underwent spectral-domain optical coherence tomography (SD-OCT) and qAF imaging on the qAF-ready Heidelberg Spectralis. 52 GA regions of interest (ROIs), or groups of adjacent lesions, were selected, and the ROIs were divided into groups by dominant AMD precursors on prior serially followed SD-OCT scans. Mean qAF values ​​and SD-OCT structural results of the groups were compared.

Results

Group 1 lesions (soft drusen precursors/PED, 18/52) were isolated, with a lower mean qAF (35.88 ± 12.75 units); group 3 lesions (SDD precursors, 12/52) were multilobular, with a significantly higher mean qAF (71.62 ± 12.12 units, p< 0.05). Group 2 lesions (mixed precursors, 22/52) had an intermediate mean qAF (58.13 ± 67.92 units). The main structural difference was the significantly higher prevalence of split RPE/Bruch's membrane complex in SDD-associated AG, suggesting basal laminar deposition (BLamD), than in drusen-associated lesions.

Conclusion

Quantitative autofluorescence (qAF) of GA lesions may reflect two distinct pathogenic pathways and structural findings, originating from soft drusen/PED and subretinal drusenoid deposits (SDD), with lower or higher final qAF values, respectively. Basal laminar deposition specifically in and adjacent to SDD-associated lesions may account for their greater autofluorescence. The potential significance of this paradigm is that it could guide, simplify, and facilitate research on geographic atrophy by dividing the disease into two components that can be studied separately.

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