ANN OPHTHALMOL. 2002;34(4)176

otherwise and justified their reasons for exclusion ofdata on each and every occasion.

Scientists poured over the data and found that 2 µmof glass had been polished off the surface of the mir-ror over what had been specified. Once they under-stood the problem, scientists set out to fabricate a pairof “eyeglasses” for the Hubble. RK would not help.PRK would not help. Not even the excimer laserwould help. In this case, refraction was produced by acomputerized manipulation of the signal from theHubble, namely, a computerized pair of eyeglasses.

There we have it. A 20-year project that cost $2 bil-lion, and we were left with a Hubble that needed eye-glasses. This is a painful lesson in the differencebetween perceived precision and true precision. It isoften easy to justify the untrue, but this path will neverlead to precision or truth. Measure it with a microme-ter, and cut it with an ax! Precisely how precise is pre-cise? The Hubble mirror was off by a mere 2 µm,wherein the thickness of a human hair is about 100 µm.

Albert Einstein was often criticized for a paucity ofreferences in his scientific articles and for refusing toread classic works in physics. In his own defense, hewould point out that his goal was to seek truth and torefine precision in science. To do this, he proclaimedthat he needed to purge himself of bias.

As did the manufacture of the Hubble mirror, itwould be both blinding and unwise for our editorialboard to present only concepts that are noncontrover-sial and popular. For the way of truth is not alwayssafe and easy. A goal of the Annals is to evaluate infor-mation from anywhere in the world in an unbiasedfashion, for creativity knows no boundaries. TheAnnals will continue striving to provide a venue thatwill guide our readers toward, rather than away, fromprecision and truth in the diagnosis and treatment ofeye disease.

Richard J. Fugo, MD, PhDMedical Editor

Improved health care depends on a never-endingquest for improved quality in both diagnostic and

therapeutic precision. Improving one without theother fails to improve the state of medicine and high-lights the carpenter’s joke: “Measure it with a microm-eter and cut it with an ax.”

In 1990, the United States delivered the Hubblespace telescope into space aboard the Discovery spaceshuttle into a 615-km orbit, the highest attainableorbit for a space shuttle. The Hubble was a showcasescientific program representing the accumulation of20 years of design, construction, and preflight testing.The main mirror for the Hubble was constructed froman 8-ft wide slab of ultra-low expansion silica glass,which cost about $1 million. The grinding of this glassinto a mirror required 2 years, and during manufac-turing the process was tested about 20 times withultrahigh precision equipment that could detect theslightest blemish or defect, such that the final productwould not vary more than 0.01 µm from tolerance.

At a cost of $2 billion, the world was mesmerized asHubble was sent into orbit by the space shuttle Dis-covery on April 24, 1990. The world now waited for themost spectacular images of space ever seen. When thefirst images from Hubble arrived back on earth, thescientific community was stunned. The images weresmeary blobs. How could a 20-year, $2 billion projectproduce an image that looked like a blob?

The best minds convened, as did US congressionalhearings. At the onset, many thought that Hubble waspermanently blinded. But why? Scientists soon dis-covered that the main mirror assembly, which cost$250 million, was defective. Hubble was not onlymyopic but also possessed substantial astigmatism.Congressional subcommittees discovered that each ofthe 20 testing periods during the fabrication of themirror produced test results showing that the mirrorwas defective, while other tests showed that it wasnear perfect. The scientists and engineers at the man-ufacturer were so convinced that the mirror was per-fect that they repeatedly excluded data that suggested

EDITORIAL

A Quest for Precision and Truth