A promising new cure for cataracts that doesn’t involve surgery is looming on the medical horizon. This is good news since clouded lenses are the #1 cause of blindness. Surgical treatment using lasers or scalpels is simple and safe enough but often uncomfortable for the patient and, in some cases, out of financial reach.
A team of scientists, led by University of California, San Diego, molecular biologist Ling Zhao, has been working on steroid eye drops that reduce and dissolve cataracts. If successful, this breakthrough technology would restore sight after cataracts have been detected and help prevent them from forming. According to their study findings, published in Nature:
“Our study identifies lanosterol as a key molecule in the prevention of lens protein aggregation and points to a novel strategy for cataract prevention and treatment.”
All animal and fungal steroids are derived from lanosterol, a chemical compound. Lanosterol is an amphipathic molecule enriched in the lens. Amphipathic molecules have both polar and non-polar parts that attract, repel or have no effect on other molecules. Water is a polar molecule: its oxygen atom pulls atoms away from its hydrogens.
The human lens is made up, for the most part, of crystallin proteins organized structurally to provide lens transparency and the correct refractive index. Any disruption of intra- or inter-protein interactions will change this delicate natural structure and expose water-repelling (hydrophobic) surfaces that allow proteins to accumulate, creating cataracts.
The exact biological mechanisms that control the lens proteins that both prevent protein build-up and maintain lens transparency are largely unknown. But the American researchers learned that children with an inherited form of cataracts shared a genetic mutation that halted the production of lanosterol in their bodies. Parents who lacked the same mutation produced lanosterol and had no cataracts.
The study authors tested both lanosterol and cholesterol to see if they could prevent protein accumulation between the cells in the eye. Only lanosterol “significantly decreased preformed protein aggregates,” both in test tube and in cell-transfection experiments.” (Cell-transfection artificially introduces nucleic acids – DNA or RNA – into cells without using a viral infection.)
The study authors found that lanosterol treatment reduced cataract severity and increased transparency in dissected rabbit lenses with cataracts in vitro (literally, “in the glass,” meaning a test tube or petri dish) and cataract severity in live dogs.
It is estimated that some 32.4 million people living today are blind. More than half of those cases were caused by untreated cataracts. Almost 22 million people older than 40 living in the U.S. have cataracts.
According to the National Eye Institute, a cataract is “a cloudy area in the lens of your eye,” and common in older people. “In fact, more than half of all more than half of all Americans age 80 or older either have cataracts or have had surgery to get rid of cataracts.”
A staggering 90 percent of all cataract cases worldwide are diagnosed in impoverished developing countries that lack the proper facilities to operate on cataracts, leaving no treatment option. Blindness is the natural result for these people.
One of my grandfathers developed cataracts after he was 90 years old. As his eyesight faded to black, we watched his morale go down. Grandpa’s cataract surgeries failed to restore his vision. Life afterward – having to be led around his own house – was too much for his cheerful disposition and his overall health went into decline.
A normal, healthy lens is clear and curved to bend light rays entering the eye to focus properly on the retina for optical transmission to the brain for interpretation of what is being seen. Over time, “crud” often builds up on the lens and physically obscures the view much like a dirty car windshield. The eyelids function like windshield wipers but are useless against cataract deposits.
A clouded lens prevents light from entering the eye to reach the proper focal point required for 20/20 (perfect) vision. Objects look hazy or blurred.
At first, cataracts present no symptoms. As they thicken, they become obvious due to the following signs:
- Blurred vision
- Seeing double (seeing two images rather than one)
- Extra-sensitive to light
- Poor night vision or needing more light to read
- Seeing bright colors as faded or yellow
After about age 40, normal proteins in the lens start to break down, causing the lens to become clouded. By age 60, most people experience some clouding of their eye lenses even if problems don’t arise for many more years.
Cataracts can be inherited so those with a family history (like me) are at a higher risk of dwindling eyesight with advancing age. Diabetes can damage small blood vessels in the eye and lead to the development of cataracts. An eye injury, eye surgery or radiation treatments on the upper body can result in cataracts, as can spending a lot of time exposed to direct sunlight, especially without wearing sunglasses. Finally, some drugs (for example, corticosteroids) may cause the early formation of cataracts.
Study co-author Ruben Abagyan talked about his team’s further plans:
“I think the natural next step is looking to translate it into humans. There’s nothing more exciting than that.”
The future for cataract treatment is certainly looking up!