In 2015 Miriam was cantering her newly-backed Exmoor pony mare through the fields when a pheasant emerged from a hedge. The pony spooked and, unsettled by the sudden weight shift of her normally balanced rider, started an impressive bronco routine. Miriam fell off and during her bucking and spinning the pony kicked Miriam directly in the face.
In many ways Miriam was lucky – things could have been much worse! The pony galloped home and was met by sympathetic yard mates who calmed and cared for her. Miriam managed to call the ambulance service and explain, through a broken temporomandibular joint, to explain where she was and call her husband. A short air ambulance ride, some morphine and 15 stitches later she was well on her way to recovery. After a couple of months, she was left with no serious long-lasting damage, just a clicky jaw and Poldark-Esque scar down the left side of her face. Or so she thought….
Five years later Miriam noticed the vision in her left eye wasn’t up to scratch. When she went for her regular optician appointment she found that not only had her vision deteriorated significantly in that eye, but that even with corrective lenses vision remained imperfect. The same thing happened, but to a greater degree, two years later so the optician referred her to the Eye Hospital. Low and behold: a traumatic cataract!
A traumatic cataract occurs when blunt or penetrating trauma disrupts the fibres of the lens. In some cases, this can lead to the lens capsule rupturing, and conditions such as glaucoma (increased pressure in the eye) or uveitis (inflammation of the eye structures), when proteins normally contained within the lens leak out into the surrounding tissues. In Miriam’s case, it is a relatively minor problem, and the doctors predicted surgery will be required but not for another decade or so.
Of course, Miriam’s first question was “what can I do to help?”. The doctors suggested she did not take up smoking, tried hard not to become diabetic, avoid any further blunt force trauma to the head or eye, and eat a good diet. So the next question is “what do you mean by a good diet?”.
On further questioning, much of the dietary advice was related to avoiding the risk of diabetes (don’t eat too much, especially too many sugars). “But what about carotenoids?” Miriam asked. The doctor replied that there is plenty of evidence that carotenoids are extremely important in maintaining and protecting a healthy retina (the area at the back of the eye containing the light-sensitive cells responsible for vision). In particular the macula, the area of the retina with the highest concentration of photoreceptors. However, a cataract is a problem of the lens, not the retina. So would carotenoids help? The doctor’s verdict was: most likely yes! There is no evidence to suggest carotenoids protect the lens, but that is because of a lack of research, rather than there being any good reason or evidence to say carotenoids don’t help.
“No evidence” means “there isn’t enough research for us to know either way”, NOT, “the evidence says no”. This is a key concept for veterinary herbalists. There will always be more research funded by pharmaceutical companies on chemical drugs than there is for herbal medicines, which are harder to monetise. There is a growing body of evidence for herbal medicine, but we also use historical records, personal experience, and scientific logic in our herb choices.
Carotenoids are terpenoids (tetraterpenes, to be exact). Terpenoids are one of the most important groups of active plant constituents. Many have a strong smell that the plant produces to deter herbivores from eating them. Carotenoids are responsible for the red, orange and yellow pigments of leaves, fruits and vegetables. In the plant, they act as antioxidants and provide protective functions by inhibiting the photosynthetic membrane’s UV-induced free radical formation. It is no surprise, then, that they have potent antioxidant properties in mammals too. Some, for example, lycopene, are linked to a reduced risk of atherosclerosis, heart disease and cancer.
In terms of eye health, carotenoids can perform a similar function to in plants – protecting against UV damage and scavenging free radicals. Others, such as beta-carotene in carrots, are pro-vitamins, used by the mammalian body to make vitamin A. Vitamin A is important for supporting cell growth, foetal development, immune function and vision. The active form of vitamin A, retinal, combines with a protein opsin to form rhodopsin – the molecule necessary for colour and low-light vision. It also protects surface tissues such as the cornea (back of the eye), conjunctiva (thin surface of the eye), skin, intestines, lungs, bladder and inner ear. It is also a vital component in the growth and distribution of T cells, a type of white blood cell that helps the body fight infection.
So, in conclusion, we know that carotenoids are important for general eye health, and other important body functions. Will they help Miriam’s traumatic cataract? We don’t know. They could certainly help with oxidative damage and protect against inflammation, and do plenty of other things to help her body too. Another good reason to “eat the rainbow”.
