Explore the fascinating journey of diabetic cataract treatments, from ancient surgical techniques to cutting-edge modern procedures that restore vision.
Eye Anatomy 101: How Visions Works
The human eye is a complex organ that relies on specialized anatomy and intricate components working together to capture and process light from our environment. The pupil—the distinctive black center of the eye—continuously expands and contracts to regulate incoming light, while the lens focuses this light precisely onto the retina. This light-sensitive layer of nerve tissue at the back of the eye then converts these signals into visual messages for the brain.
There are many conditions that affect the eye’s ability to function properly, one of which is cataracts. When the eye has a cataract, it means the lens has become cloudy, either partially or in entirety. Cataract symptoms include vision that is:
- Blurry
- Hazy
- Less colorful
Though cataracts have been documented throughout human history, modern medicine has transformed their treatment. An estimated 3.7 million cataract surgeries are performed annually in the United States alone. This journey from ancient surgical attempts to today’s routine procedure tells a story of medical advancement, beginning with the earliest cataract surgeries documented thousands of years ago.
How Diabetes Can Lead to Cataracts
Several factors can increase a person’s risk of cataracts, including age, medications, and certain medical conditions, such as diabetes. When the eye is affected due to diabetes, it is known as diabetic eye disease. These complications of diabetes affect almost 10 million people across the U.S.
They include:
Research indicates that cataracts are relatively common in people with diabetes, with CDC data estimating that 32% of people over 45 years of age with diabetes in the U.S have cataracts.
But how can diabetes lead to cataracts? When a person has diabetes, this can lead to high levels of glucose in the body. When this happens, the high blood glucose triggers the polyol pathway in the eye. This pathway converts the excess glucose to fructose in two steps:
Glucose → Sorbitol, Sorbitol → Fructose
This conversion leads to high levels of sorbitol in the eye. When this excess sorbitol accumulates in the lens, it can lead to clouding.
People with diabetes may develop several types of cataracts, each of which can cause a whitish clouding of the lens that can impair vision. These types include:
- Posterior subcapsular cataracts (PSC) occur on the back of the lens, directly in the light path.
- Cortical cataracts where the middle and outer layers of the lens become cloudy.
- “Snowflake” cataracts are rare and cause scattered clouding of the lens.
Historical Cataract Surgery: The Couching Technique
The couching technique was first described in the Sushruta Samhita, an Indian surgeon and physician in the 6th century B.C, although the procedure’s exact origins are still unclear. It is possible that before this written documentation, couching was performed by traditional healers who would have not written down their methods.
In this technique a sharp needle is used to dislodge the cataractous lens from it’s original location. This can either be done by using the needle to break up the lens or removing it in one piece. The lens is then pushed into the vitreous cavity, the gel-like substance in the back of the eye.. Below are examples of couching needles from the 16th century. There is also documentation as late as the 1900s that thorns were used for couching.
With couching, the lens is not removed from the eye, rather it is pushed away which then allows light back into the eye. While it may provide some relief from symptoms, up to 70% of people experience blindness as a complication from the procedure.
It is a traumatic procedure that causes inflammation and runs the risk of infection. As the lens is not removed from the eye, there was the possibility the lens could migrate within the eyeball, sometimes back to its original position which would then lead to the original cataract problems. Afterwards, patients are left without a lens in its original position which can lead to several vision issues. Other complications from couching include:
- Glaucoma
- Retinal detachment
- Vitreous hemorrhage
Couching remained the primary surgical method for cataracts for over 2,000 years.
Modern Surgical Advances for Patients With Diabetes
There have been several advancements in cataract surgery since couching. These include different surgical methods as well as lens replacements.
Extraction: Removing the Cloudy Lens
The original method used an oral suction device to suck out the lens from the eye once it had been dislodged. The benefit of extraction is that the lens is removed from the eye rather than being pushed into the vitreous cavity where it might migrate within the eye. However, as with couching, the patient still does not have a lens, which can lead to various vision issues.
Daviel, a French ophthalmologist, was the first European to successfully perform cataract extraction surgery in 1747, which marked the beginning of a new era in cataract surgery.
Intraocular Lens (IOL): The Synthetic Solution
An Intraocular Lens (IOL) is a replacement lens inserted in a patient’s eye after cataract surgery. The first attempt at this was in 1795 by Johan Virgilius Casaamata when he inserted a glass lens. However, this material proved to be too heavy and it sank into the patient’s eye. It wasn’t until 1950 that the next big era of cataract surgery emerged when Henry Ridley, an English ophthalmologist, placed the first permanent Intraocular Lens (IOL) in 1949, this time made of a flexible type of plastic. Using a plastic IOL restores vision without the need for heavily corrected glasses and to better quality. Today, using an IOL after cataract extraction this is the most common type of cataract surgery performed.
Phacoemulsification: Minimally Invasive Cataract Surgery
In 1967, Charles D. Kelman, a US ophthalmologist, developed a method of cataract removal that required only minimally invasive surgery. In this method, an ultrasonic probe is used to break up the cataract through a small incision in the eye. Then, the lens is replaced with an IOL. Pharmacoemulsion allows for less time in hospital and makes surgery less painful.
Summary
Cataracts occur when the lens of the eye becomes cloudy and impairs vision. Cataracts can happen due to many factors including regular aging but some cataracts are caused by conditions such as diabetes.
Regardless of the cause, the treatment for cataracts has always required surgery to remove the cloudy lens with newer advancements making surgery less invasive and the replacement of the lens possible.
Regular eye exams are important for catching cataracts early as cataracts may not always cause symptoms if they only occur in the periphery of the lens. Early diagnosis can lead to earlier treatment which can increase the chances of preserving vision.
Sources
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Isabella De Soriano is the Fall 2024 Marketing Intern at the IMSS. She is a medical history and oddities enthusiast with a love of taxidermy. Based in Chicago with an education in anthropology and public health from the University of Iowa, she’s interested in how medical narratives reflect understandings of society.