Science Q & A: Does this easy ploy really kill bed mites?

Q. Does an unmade bed kill dust mites?

A. Keeping relative humidity low in the home does help fight irritating dust mites, studies have found, but a British study, widely reported as having concluded that leaving the bed unmade could do the trick, suggested only that it might do so. Actual scientific comparisons of made and unmade beds were not done.

Dust mites, like Dermatophagoides pteronyssinus and Dermatophagoides farinae, are microscopic, eight-legged creatures that feed on skin cells. Their feces can set off asthma symptoms and cause allergic reactions in some people.

The British study, published in 2006 in the journal Experimental and Applied Acarology, suggested a computer model for predicting the effect on dust mites of different ranges of temperature and relative humidity. The researchers said they planned followup studies under real conditions, but have not reported on any.

Government recommendations on fighting indoor biological pollution suggest familiar tactics, like using dustproof mattress covers and washing bedding weekly in very hot water.

‘Clouds’ inside your eye

Q. What causes floaters in the eyes?

A. Floaters, those small dots or cobweb-shaped patches that move or “float” through the field of vision, can be alarming. Though many are harmless, if you develop a new floater, “you need to be seen pretty quickly” by an eye doctor in order to rule out a retinal tear or detachment, said Dr. Rebecca Taylor, a spokeswoman for the American Academy of Ophthalmology.

Floaters are caused by clumping of the vitreous humor, the gel-like fluid that fills the inside of the eye. Normally, the vitreous gel is anchored to the back of the eye. But as you age, it tends to thin out and may shrink and pull away from the inside surface of the eye, causing clumps or strands of connective tissue to become lodged in the jelly, much as “strands of thread fray when a button comes off on your coat,” Taylor said. The strands or clumps cast shadows on the retina, appearing as specks, dots, clouds or spiderwebs in your field of vision.

Such changes may occur at younger ages, too, particularly if you are nearsighted or have had a head injury or eye surgery. There is no treatment for floaters, though they usually fade with time.

But it’s still important to see a doctor if new floaters arise because the detaching vitreous gel can pull on the retina, causing it to tear, which can lead to retinal detachment, a serious condition. The pulling or tugging on the retina may be perceived as lightning-like flashes, “like a strobe light off to the side of your vision,” Taylor said.