For the first time, two different common eye diseases were discovered that could cause blindness to the eye

According to a new study from Mount Sinai New York Eye and Ear Hospital, two different eye diseases can contribute to age-related macular degeneration (AMD), the leading cause
of blindness in the United States.

The study, published Jan.
9 in the journal Eye, is the first to demonstrate that two different types of deposits on the retina can cause early AMD, and may progress to advanced AMD and blindness
.
These two diseases can 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, age-related macular degeneration is caused by damage to the macular area in the middle of the retina, which is responsible for reading and driving vision
.
Nearly 20 million Americans age 40 and older have some form of macular degeneration
.
Early forms of AMD are currently considered a single disease
containing cholesterol deposits.
These deposits are called drusen and subretinal drusenoid deposits (SDD).

Early AMD can develop into two advanced forms of blindness, commonly referred to as wet AMD and dry AMD
.
Ophthalmologists call this advanced dry lesion geographic atrophy (GA).

"An amazing fact is that the retina can produce fluorescence, similar to a light fixture, but a million times
dimmer.
This is the first time we've been able to study advanced AMD
with an ultra-sensitive detector measuring this dim light, known as autofluorescence (AF).
We found that when SDDs patients reached advanced AMD, they were consistently twice as bright as drusen patients and came from a unique layer of lesions," said lead author R.
Chenai, professor of ophthalmology at the Icahn School of Medicine at Mount Sinai.
Theodore Smith, MD
, explains.
"Combined with our previous research, this provides conclusive evidence that AMD is undergoing two different disease processes, one with darker fluorescence and drusen, and the other with brighter fluorescence and SDD, which need to be treated
differently.
"

Drussen's formation can be slowed down with proper vitamin supplementation to prevent vision loss
.
Currently, there are no known treatments, and they pose a greater threat
to advanced AMD.
However, in a previous recent study, Dr.
Smith and a team of researchers at Mount Sinai School of Medicine found that SDD patients are likely to have heart damage from heart failure and heart attack, or advanced valvular heart disease, or stroke
associated with carotid artery disease.

"We believe SDDs are caused
by insufficient blood flow to the eye caused by these vascular diseases.
Therefore, we believe that patients with SDD should be warned that they may have life-threatening undetected heart disease that should be evaluated and treated
.
Further research is needed in women and vulnerable groups, as neglected heart disease in these groups is a serious problem
.
An eye scan of SDD and a routine cholesterol blood test can solve this problem
.
In addition, treating cardiovascular disease and restoring blood supply to the eye may also help SDD
.
This work should prompt retinal specialists to look for drusen and SDDs with optical coherence tomography (OCT), a standard retinal imaging technique, to provide the best recommendations
for patients.

The new study measured autofluorescence in 18 (32 eyes) patients with advanced AMD and geographic atrophy (GA) and evaluated OCT scans
.
Because GA can occur in multiple regions of the retina, the researchers analyzed 52 GA regions
.
They also selected only patients who had had OCT scans in the past three years so they could determine whether the lesion area started with Drusen, SDD
, or both.
Of these regions, 18 originate from Drusen, 12 from SDD, and 22 from a mixture
of Drusen and SDD.
The team then measured the brightness
of fluorescent lamps from these areas with a very sensitive light meter.
They found that patients with SDDs were twice as bright as Druson patients
.
Specifically, the average luminance reading was 72 in the SDD group and 36 in the drusen group, with readings in the mixed group somewhere in between
.

"All of these numbers translate into a basic fact — AMD has two different diseases, Drewson's disease and SDDs," Dr.
Smith said
.
"The good news for patients and ophthalmologists is that in the clinic, we don't need advanced atrial fibrillation measurements to know which type of AMD a patient has
.
As our research shows, these two forms are associated with Drusen and SDD, deposits that can be identified
by standard retinal imaging.
Therefore, diagnosing which type of AMD a patient has becomes very important
for the treatment and prevention of the disease.
”

The research was funded
by researchers at Regeneron Pharmaceuticals, the Blindness Prevention Challenge Research Fund, the Macula Foundation, the Bayer Global Ophthalmology Award, and the International Council of Ophthalmology Alcon Fellowship.