There are two types of farsightedness: hyperopia and presbyopia. Hyperopia, where the eye is shorter than usual, is a condition you’re born with, but which gets worse over time. Presbyopia is where eye muscles become rigid and the eye lens is less able to focus. This is usually noticeable around age 40, when many people find they are unable to focus sharply on close objects.

Medicine has no prevention or treatment for presbyopia other than various types of corrective lenses. As the condition progresses, many end up with two sets of glasses - one for up-close work and one for seeing farther away.

However, a new technique called ‘conductive keratoplasty’ (CK) uses radiowaves to create a constricting band of collagen around the eye to increase corneal curvature, bringing near-vision back into focus. Known as ‘monovision’, it is only done on one eye, so the other eye can focus on the distance. Optometry can do the same thing with different fixed lenses, but it’s a compromise, not a cure.

To slow the progression of presbyopia and perhaps even improve vision:

* Eat well. A diet that includes green leafy vegetables and grains will lower your likelihood of eye diseases such as macular degeneration and cataracts. Adequate protein is also important as the eyes require the full range of essential amino acids.

* Take regular aerobic exercise, which encourages circulation and, thus, the transport of nutrients to your eyes.

* Avoid long hours focused on a computer screen. Take frequent breaks to allow your eyes to focus naturally on faraway objects, and work under adequate, but not glaring, light.

* Clean eyes twice a day with cool, clean water.

* Try Shiatsu or acupressure, and learn which acupoints can help to maintain good vision and eye health.

* Avoid environmental toxins, like pesticides, which can damage the eye (Invest Ophthalmol Vis Sci, 1981; 21: 700-13). Likewise, take care when using shampoos and hair dyes, which can harm delicate eye tissues (Am J Optom Physiol Opt, 1982; 59: 1002-4).

* Manage chronic stress, linked to eye diseases like glaucoma, with biofeedback, meditation, yoga or tai chi.

* Avoid corrective lenses if you don’t need them as they may worsen vision over time (Ophthalmic Physiol Opt, 2003; 23: 13-20).

* Wear sunglasses as excessive exposure to heat and light can prematurely age the eye (Dev Ophthalmol, 2002; 35: 40-59).

* Do eye exercises. Dr Marc Grossman offers exercises for presbyopia (www.visionworksusa.com; $12), or try the Bates Method (Bates WH, Better Eyesight Without Glasses, NY: Owl Books, 1981; www.seeing.org).

* Supplement with antioxidants (vitamins A, C and E) and 20 mg of lutein plus 1 mg of zeaxanthin daily, potent free-radical scavengers in the retina. Vinpocetine (periwinkle) 5-10 mg/day improves blood circulation to the eye.

Pat Thomas