Thank You Dr. Grolman - by Dr. Ken Myers

Inventions seldom proceed smoothly and may arise from research directed to other ends or unexpected observations. Teflon, for example, was discovered as a residue of chemical reactions designed to produce something else and was only "noticed" because it was a waste product hard to remove.

Nor is the law of unexpected consequences shy to raise its head. For example, the original optometry acts contained medication bans not at the request of medicine, but at the request of our forefathers. This was because Prentice, in New York, who triggered the issue, had been accused of practicing medicine without a license only after he began to charge for his examinations and his defense was characterized by the "A Lens Is Not A Pill" pin that early optometrists began to wear and hand out to politicians. Thus, when the first licensing acts were written it was optometry that insisted they exclude medications while organized medicine insisted they not be required to hold an optometry license to refract.

And much of history is unrecorded. Have you ever wondered why the first optometry licensing law was enacted in Minnesota in 1901 when the action seemed to be around Prentice in New York? Last year I happened to sit next to two officers of the Minnesota Optometry Association at lunch and I asked them about this. They said they had wondered themselves but had been unable to secure the early records due to a fire but, they hoped to one day solve this puzzle.

In the late 1950's, Bernard Grolman, O.D., a member of the Research and Development Group at the American Optical Corporation in South Bridge, Massachusetts felt insulted while driving to work after hearing a radio "public service" announcement proclaiming only medical doctors were able to protect the public from the danger of glaucoma. This "public service" ad had been paid for by the Massachusetts Society of Ophthalmologists and Bernie once told me that "personal annoyance… really anger, led me to consider diverse non-contact means of IOP measurement". At that time no state allowed optometrists to use medications and it wouldn't be until the early 70's that the first licensing law was changed to include diagnostic agents. Thus optometrists could not use the Goldmann tonometer and this radio ad used this instrument as a marketing tool. This radio ad however, led to unexpected consequences.

In those days optometrists were mainly limited to using the McKay-Marg tonometer that, in principle, didn't require corneal anesthesia but wasn't easy to use and required tapping a small sensor probe (covered by a thin, rubber boot) against the cornea and interpreting an inked graph the sensor produced. Using the MaKay-Marg was difficult and, because it was then still widely believed that only those over 40 needed tonometry (a court had yet to rule tonometry ought be performed on everyone), many optometrists did not measure IOP.

As a result of that radio ad, Bernie Grolman, a quiet, polite and precise man, spent most of his next 10 years designing and painstakingly testing a new tonometer that would change our professional lives and become widely used throughout the world.

He graduated from the Brooklyn Polytechnic Institute in 1942 and had worked for GE as a draftsman before serving as a Navy radarman from 1944 to 1946. After discharge he apprenticed as a diamond setter but began to experience visual problems and consulted an optometrist who solved his vision problems and interested him in optometry. Grolman entered Hofstra College under the GI Bill as a pre-optometry student and in 1952 graduated from Columbia University's optometry program with a B.Sc. and M.Sc in optometry and became licensed to practice.

Ironically, due to professional politics, Columbia's optometry program (a part of the physics department) was later forced to close but this led to the founding of the Optometric Institute of New York which became the SUNY State College of Optometry; due primarily to Dr. Norman Haffner's untiring efforts over a 30 year period. Like Grolman, Haffner only works harder when told something can't be done. And prejudice by one profession against another is anathema to both men.

By the time he completed his optometry degrees Grolman "was confronted with serious doubts about my ability or desire to service the public" and was attracted, instead, to optical engineering and became a development engineer at the Burroughs Business Machines Corporation designing and testing optical, telescopic missile tracking systems from 1952 to 1955. While this work was "interesting and challenging" it had little to do with the eye so when given an opportunity to join American Optical he "jumped at the chance".

After hearing the radio spot, Grolman wondered how he might measure IOP without "touching" the eye and came to believe that the eye, a fluid filled globe, should have a resonant frequency of mechanical vibration that would depend upon the IOP--- eyes with higher IOP would resonant at higher frequencies. Every object has a resonant frequency of vibration, a frequency at which it most easily vibrates. Bells, tuning forks and piano strings for example, but also other objects, even buildings and bridges. Most people have owned a car with a resonant vibration frequency at a certain speed---go faster, or slower, and the vibration is less. And buildings that collapse during an earthquake may have resonant frequencies close to those of the earth tremors.

Grolman reasoned that the eye's natural resonant frequency of vibration should, like a piano string, vary with its tautness and eyes with higher IOPs would have higher resonant frequencies. He thought that if he could develop a table of ocular resonant frequencies Vs IOPs an instrument that measured an eye's resonant frequency could be used, with this table, to determine IOP. Just as a Schiotz tonometer reading was converted into IOP using a table.

His work then was to learn how to induce, and measure, resonant eye vibrations and document how they varied with IOP and devise a non-contact clinical instrument that could measure any eye's resonant frequency.

The first step was to get an eye to vibrate at its resonant frequency and now the unexpected occurred. Grolman had begun by directing sinusoidal sound waves of increasing pitch from a loud speaker to an eye on which a high-speed camera was focused to record any vibrations. He found he could produce an almost step function corneal "displacement" using a noisy discharge from an automobile spark plug to drive the speakers.

To his surprise he found the high-speed film frames (5,000 frames/second) showed these air pulses striking the cornea were flattening its apex but not exciting ocular vibrations. He had failed to induce vibrations but had found a pulse of air could applanate the cornea.

After years of further empirical study and seemingly countless designs, Grolman produced a single stroke, solenoid-activated air pump that, connected to a tube of certain dimensions, produced an air pulse of increasing (ramp-like) pressure that lasted but a few milliseconds yet applanated the corneal apex like a Goldmann tonometer's tip. The applanation was reproducible and grew in size as the air pressure grew with time and, since the air pulse's pressure increased linearly with time, he could determine the pulse pressure required to produce a standard amount of applanation by measuring the time it took to do this. If he knew the time he knew, indirectly, the IOP.

After many studies using first artificial eyes, then rabbit eyes and finally human eyes, Grolman had documented that the longer the air jet was allowed to build up, the larger the area of corneal applanation. Since he knew how the air pressure increased with time he could use time taken to reach a standard degree of applanation as a "correlate" to IOP. To do that however, required much data gathering with his instrument and a Goldmann on human subjects to develop a table to convert time required to reach applanation into measurements of IOP. Later, the final instrument would make this conversion electrically and display the IOP in an illuminated, digital readout display.

Other advantages to this method then became apparent. Unlike a Goldmann tonometer that contacts the cornea for several seconds (and moves while in contact) the air pulse lasted only 3-5 milliseconds so if a patient began to blink at the sound of the instrument "firing', the measurement was done before the eye lid could descend.

Only air "touched" the eye which removed the risk of ocular infection possible with mechanical tonometry and studies found the brief air applanation was so non-traumatic an eye could be measured a hundred times without detectable aqueous message (lowering of successive IOP readings) or the significant corneal staining often produced by Goldmann.

Since no corneal anesthetic was needed this technique would be Grolman's response to those radio spots and open the door for rapid, routine and accurate IOP measurements by optometrists. Or anyone else for that matter since it took but minutes of training to use the prototype.

What remained for Grolman was to determine the time it took for the air pulse to applanate the cornea and correlate those times with IOPs.

Grolman fitted the prototype with a narrow infrared (IR) beam angled that reflected off the corneal and was sensed by an IR detector on the opposite side of the cornea. When the corneal apex was spherical it scattered the IR beam in all directions but, as the air pulse flattened the apex, it increasingly reflected more of the IR beam into the detector. The more applanation, the higher the IR detector read and Grolman had a way to determine the degree of applanation with the time taken by the air pulse to produce that applanation and had the key pieces in place.

He next discovered that beyond a certain time the corneal apex began to become concave, causing the intensity of the reflected IR beam to decreased rapidly while after the air pulse ended the cornea recovered another peak of reflected IR light was detected at a second applanation with the cornea rebounding. The time when the IR detector first read maximum was then correlated with IOP.

Grolman had devised an air pulse that:

o Increased in a known, repeatable manner.

o Flattened the corneal and caused the reflected IR beam to peak at applanation.

This meant applanation occurred when the reflected IR beam reached maximum so his technique measured not air pressure at applanation but time taken to reach applanation. Grolman had a correlate of IOP ---time taken to reach applanation--- different from the one used by Goldmann---force used to reach applanation---so Grolman had only to calibrated time to applanation vs IOP just as Goldmann had calibrated force used to reach applanation vs IOP.

Much work remained to produce a practical instrument of course. Grolman had to devise an optical alignment system to accurately place the air nozzle on the corneal axis a set distance away, a patient fixation target and develop measuring circuits to detect the time taken to reach applanation. Then measure many subjects with Goldmann and the prototype NCT over a wide range of IOPs to develop the time v IOP correlation, document if the air pulse harmed the cornea (glass particles bounced harmlessly off rabbit corneas) and whether corneal astigmatism affected the instrument.

It was after about 10 years that the new tonometer--a non-contact tonometer (NCT)--- was introduced late in 1971 at the Annual meeting of the American Academy of Optometry in Toronto and later at the World Optical Fair in the spring of 1972.

Early in 1973, the AO Non-Contact tonometer appeared in our clinic. Seeing it operate was a revelation. After a few minutes training anyone could measure IOP in both eyes, several times, in under a minute. No anesthetic was needed and there was no risk of infection or trauma to the cornea. A faculty member, Dr. Witenberg, conducted a study that found the optimal technique was to use the median of three successive readings.

The AO NCT was rapidly accepted and flourished although AO changed ownership several times and the instrument is now in its 4th generation. The first version was followed by the NCT II (revised electronics) and then the Reichert and Lecia Xpert tonometer series. The most recent Xpert version does not require a chin rest, automatically aligns to the patient's cornea, and has a less powerful and quieter air pulse whose pressure and all models of the NCT are found through out the world.

But inter-professional politics affected how the NCT was initially viewed in some quarters and would not have occurred had the instrument been introduced today.

The NCT came out while the first efforts were being made by optometry to update obsolete optometry laws. Those ophthalmologists opposed to these changes viewed Goldmann tonometry as one thing that distanced them from optometrists--- the radio spots Grolman heard were one example and, human nature being what it is, some ophthalmologists questioned whether the NCT was accurate.

Soon a German ophthalmologist published an early review that incorrectly alleged the NCT was less accurate than a Goldmann (at higher pressures) and this was believed by some ophthalmologists and optometrists.

That sole claim was refuted by many studies over the last 30 years but is still occasionally believed, I regret to say, by some although all NCT models meet the ISO tonometer requirements.

As accurate as the Goldmann, the NCT however:

o Does not depend upon operator skill or subjective criteria.

o Poses no risk of infection.

o Automatically checks calibration at start-up.

o Provides a printed record of IOP.

o Activates a "low confidence" light when internal parameters are non-optimal.

o Lends itself to rapid, mass IOP screenings

But even today if an NCT reads a high pressure a repeat measurement with the Goldmann is sometimes done to "verify" the NCT reading when, in truth, the NCT can, as logically, "verify" a Goldmann reading since there are more factors that can adversely affect a Goldmann than an NCT.

This is not to denigrate the Goldmann. It remains, an excellent instrument and was a great improvement on the Schiotz, an instrument requiring even more skill and even more open to cornea trauma and spread of infection. And today most clinicians have NCT and Goldman tonometers and use both.

Dr. Grolman held 45 US patents and developed other ophthalmic instruments besides the NCT and served as Chief Scientist at his company for 18 years before "retiring" in 1985 but remained an active consultant and was awarded honorary doctoral degrees by the Illinois College of Optometry and the New England College of Optometry and, in 1990, the William Feinbloom Award from the American Academy of Optometry.

Dr. Grolman was in Buffalo, NY last month when he was stuck and killed by a car. He had been working that day with his colleague Dr. David Luce on forthcoming clinical trials of a new NCT. He was preceded in death by his loving wife and is survived by 5 children and multiple grandchildren who mourn his passing.

I knew Bernie for 30 years and will remember his inventive genius, kindness and "old school" manners. No one who knew him failed to respect and like him.

And for all of us who use NCTs in our daily practice…Thank You Dr. Grolman.

Return to In Memory of Bernie Grolman page

Dr. Bernie Grolman 2002 Interview on his Non Contact Tonometer Invention (provided by David Taylor) New July 30, 2009