A brief history of amblyopia: defining it, detecting it & treating it
Have you ever wondered when amblyopia was first identified? Or when vision screening began?
I have. I’m not a historian, but the topic interests me, and I wanted
to learn more to help put thework we’re doing today in context. Amblyopia isn’t a new condition.
Early evidence is seen in a statue of Djoser, an Egyptian pharaoh, that dates to 2723 BC.
The statue depicts a significant strabismus which mostly likely means he developed amblyopia.
Fast forward to 400 BC and Hippocrates, the father of medicine. He described amblyopia in the
following way: when the doctor sees nothing and the patient sees nothing, the diagnosis is
amblyopia. This is considered the first definition of amblyopia, which comes from the Greek
“ambly,” meaning dull or lazy, and “ops,” for the eye.
Ancient treatments build a foundation for modern practices
Over a millennium later, an Egyptian named Paulus de Aegina was the first to treat strabismus.
He developed a face mask with perforations to force people to look in specific directions. Masks
continued to be used to correct strabismus, even as late as 1600 when German physician
Georg Bartsch developed elaborate masks, one for endoscopia and another for exotropia.
Surprisingly, the first use of an eye patch was proposed by Turkish physician Thābit ibn Qurrah
al-Ḥarrānī in 800 AD. It’s surprising because patching a child’s eye is still the most effective
amblyopia treatment.
Early ophthalmology tools are still used today
Screening and diagnostic tools developed more than 170 years ago are similar to what we use
today. The first visual acuity wall chart was created in 1843 by German ophthalmologist Heinrich
Kuechler. These paper charts were developed before hyperopia was defined. The medical
community knew about amblyopia but didn't understand its risk factors. Amblyopia that
developed due to hyperopia or myopia was often attributed to strabismus.
A few years later, another German ophthalmologist, Hermann von Helmholtz, invented the
ophthalmoscope which allowed for a first look inside the
patient’s eye at the lens, retina and optic nerve. He is known as the father of modern
ophthalmology. Thanks to von Helmholtz's ophthalmoscope, another prominent ophthalmologist, Frans
Cornelis Donders of the Netherlands, was the first to describe hyperopia in 1859.
This predecessor to photo refraction was challenging, and lenses needed to be added to see
the retina clearly. Today, primary care physicians use an updated version of the
ophthalmoscope during pediatric and adult exams when they want to look at the fundus.
It’s also a tool used to compare the color,
brightness and symmetry of the ‘light reflex’ obtained from both eyes (often called Bruckner test
or ‘Red reflex test’). The lack of any of these variables might be due to the presence of
amblyogenic risk factors, that makes the ophthalmoscope a useful tool in the Pediatric office.
Making the connection between vision screening and child development
A Connecticut school screening program launched in the late 1800s is the first evidence of
vision screening. Unfortunately, the process wasn’t standardized, which made evaluating the
outcomes difficult.
Dr. Albert Sloan, a Massachusetts ophthalmologist, used an early Snellen chart to develop a set
of vision screening tools for schools in 1938 that was used widely in the 1940s and 1950s.
Other Snellen charts and tests were used during this same period for school screening, and the
American Medical Association approved this more formal approach. At the time, the medical
community recognized the consequences of amblyopia on child development. This movement
led to the development of new tools for screening. But photo refraction was still another decade
away.
Early photo refraction equipment developed in the 1960s used isotropic photo refraction in
which the light source was coaxial to the camera's sensor. The weakness of this system was
that it required robust calibration every time.
In a 1970s Harvard Medical School lab, David Hubel and Torsten Wiesel made a breakthrough
in amblyopia research. Their experiments demonstrated the physiological reasons why myopia
needs to be treated before ten years old. They received the Nobel Prize for that work in 1981,
and their work led to a significant increase in amblyopia research.
The first photoscreening system was commercially available in the 1990s. It was a Polaroid
camera that had pictures attached to attract a child’s attention. In 2002, the American Academy
of Pediatrics recommended photoscreening for the first time.
Photoscreening ushers in the next chapter
Modern photoscreening devices detect amblyogenic risk factors that might lead to amblyopia,
including myopia, , hyperopia, astigmatism anisometropia and strabismus. Pediatricians tell us they love these
tools because they work like automatic ophthalmoscopes. Because of the adjustment
ophthalmoscopes need, they’re hard to use with an adult who will sit still, let alone a child.
It's been interesting to learn more about the evolution of ophthalmology innovations over
thousands of years. Each is built on the previous breakthrough. The work GoCheck Kids is
doing now with photoscreening and visual acuity testing on a smartphone makes us part of this
story, this history. And that’s pretty cool.
