The Background of Corneal Reshaping

THE STUDY OF VISUAL PROBLEMS, mainly poor vision, began in the early sixteenth century when Leonardo da Vinci contemplated the possible source of visual disturbances. A little later, in 1619, Scheiner measured the anterior surface of the cornea. His discoveries are still used by ophthalmologists who recognize that refractive surgery often depends on changing the cornea’s anterior contour. Even lens removal, similar to cataract surgery, as a means of correcting high degrees of myopia was discussed by Boerhaave in 1746. But real progress in the field of vision correction was constrained until researchers gained a better understanding of how the eye functioned.

Johannes E. Purkinje observed in 1823 that images form on optical surfaces when they reflect external light. His observations led to the development of the Purkinje principles and the four Purkinje images. From these devel-opments our modern-day understanding of keratometry (measuring the curvature of the cornea) and theories of vis-ual accommodation began to grow.

Several decades later topical anesthesia (eye drops) was developed, which led to cataract surgery after the Civil War. In 1867, with the development of the ophthalmometer (an instrument for measuring the curvature of the cornea), surgeons could measure astigmatism following cataract surgery.

In 1869 Snellen (after whom the vision charts of today are named) proposed using incisions across the steep meridian of the cornea to flatten it and treat astigmatism. However, twenty-one years would pass before anyone (Galezowski) would actually attempt to reshape the corneal contour.

TRIALS AND EXPERIMENTATION
Not long after a successful cataract surgery technique was developed by van Graefe in the 1850s, ophthalmologists everywhere began to recognize the impact of corneal shape on astigmatism. In 1895 Faber performed a full thickness corneal incision to decrease naturally occurring astigmatism in a nineteen-year-old patient, thus enabling the young man to pass his vision test for entrance into the Royal Military Academy. But all of these efforts were focused on astigmatism; no one looked beyond astigmatism to myopia or hyperopia. It soon became apparent that a better understanding of the principles of keratotomy (the making of incisions in the cornea) was needed before any further progress could be made. No one thought in terms of non-surgical corneal reshaping, at least not in the early years of study.

It was about this time, in the late 1890s, that a Dutch physician, Leendert Jan Lans (working at the time on his doctoral degree), began to systematically study and de-fine the principles of keratotomy. So fundamental and comprehensive was his research that it soon became the standard of refractive surgery. He practiced and promoted the principles of corneal flattening that could be achieved by incisions made on the anterior surface of the cornea. By varying the number, direction, and shape of the incisions, Lans could manipulate the effects and tailor the visual correction.

Since the surgical cutting of the surface of the eye was a very risky procedure, not many eye surgeons were willing to risk a patient’s vision on this new technique.

In addition to surgical techniques, there were non surgical attempts at reducing myopia by manipulating the shape of the cornea. One remedy was an eye cup with a spring-powered mallet designed to flatten the cornea; an-other was a firm rubber band used to flatten it. The Chinese used sandbags on the eyes while the patient slept to flatten the cornea. But these were techniques that failed to result in any significant degree of visual correction. However, those who tried to avoid surgery and still reshape the cornea knew that it could be remolded without surgery, because the cornea was pliable.

With the exception of the work performed by Lans, 1885 to 1939 was principally a time of trial and error for refractive surgery and other methods of reshaping the cornea. Nevertheless, the successes and failures of this period helped determine which refractive procedures worked and which did not.

In 1936 Tsutomu Sato observed a flattening of the cornea in patients who had sustained traumatic injury to the eyes. The corneas of these patients were irregular and abnormally steep, like keratoconus, but reshaped after episodes of corneal swelling. His work led numerous assistants to establish the value of radial keratotomy, built upon the principles outlined by Lans nearly half a century earlier and applied to the treatment of keratoconus corneas. Sato brought anterior and posterior keratotomy to clinical prac-tice in hundreds of patients and reported his results in the early 1940s. Other ophthalmic surgeons subsequently used his technique and obtained similar results.

It appeared that the only method for reshaping the eye was surgery. This went on into the 1960s as ophthalmic surgeons wrestled with the idea of cutting into the cornea to reshape it.

Sato also applied his posterior keratotomy technique to the correction of astigmatism; this technique involved the disruption of the corneal endothelium, the internal cells on the backside of the cornea. Unfortunately, the role of the corneal endothelium in maintaining corneal thickness and clarity was not fully understood in Sato’s time, and the subsequent development of corneal swelling in the majority of his patients who received this treatment went undetected until after his death.

In 1948 Ridley, a physician to Royal Air Force pi-lots in World War II, noted that pilots whose eyes harbored slivers of Perspex from the cockpit glass shattering during combat seemed to have little or no reaction to this foreign material. This led him to suppose that a small lens made out of the same material could probably be tolerated inside the human eye. Soon he began experimenting with plastic lens designs, and the modern era of intraocular lens implantation for cataract surgery was born.

About the same time that Ridley envisioned the plastic intraocular implant, José Barraquer in Columbia de-veloped the idea of lamellar (layered) corneal surgery to alter the shape of the cornea. He discovered that lamellar keratoplasty could reshape the cone of some keratoconus patients, significantly reducing myopia.

In 1949 Barraquer described the principles of lamellar surgery. He changed the cornea’s shape by re-moving the anterior cornea (the equivalent of today’s cor-neal flap) with an instrument called a microkeratome, freezing it, and changing its shape with a mechanical lathe called the cryolathe. The new surgical procedure was called keratomeulosis.

Contact Lenses
The earliest description of a lens created with contact to the eye was Leonardo Da Vinci who it is reported to have placed his face in a clear hemi-spherical glass bowl filled with water and could see past the bowl.

The modern history of contact lenses also begins in the 1823 when Sir John Herschel proposed treating irregular corneas with a contact lens device. It wasn’t until 1888 that A Eugen Fick described the successful application of glass contact lenses that were equal in diameter to that of the cornea. About that same time E. Kalt reported to the Academy of Medicine in Paris his successful application of a contact lens.In addition to a blind patient being able to read a newspaper wearing contact lenses, the patient was able to see well for hours after removing the lnes. The report he submitted is actually the first report of corneal molding by contact lenses.

. . ."the cornea, being very thin, conforms exactly to the concavity and finds itself, from doing so, straightened out." He concludes, " the optical correction is brought about in a manner that is quite satisfactory. The future only will show to what degree the effect is curative."

THE ADVENT OF A NON-SURGICAL RESHAPING

In the mid-1960s two young optometrists, Drs. Charles May and Stuart Grant, read Dr. George Jessen’s paper on "Orthofocus Techniques" that referenced to the changes in refractive error by the use of rigid contact lenses. They took Dr. Jessen’s challenge—if reshaping of the cornea to lessen myopia could happen without conscious effort, maybe a deliberate effort might get even better results.

Charles May and Stuart Grant stepped up their research on the possibilities of creating a method of cornea molding with contact lenses. In 1964 the two doctors published a paper titled, Emmetropization Through Contact Lenses. This opened the door to modern, non-surgical, corneal reshaping. They considered the fact that most well-fit, rigid contact lenses, worn for a period of time, brought about a decrease in corneal curvature and that this worked to the advantage of those suffering from nearsightedness (myopia). The name orthokeratology was coined as the medical name of the procedure shortly after this time.

A common fitting modality during this period was to align the base curve (the central back surface) of the contact lens with the flattest corneal curve, thus the term "alignment fitting." Over the next three decades there began a concerted effort by other doctors to alter the contact lens base curve to flatten the corneal curvature. By changing the lens, size, thickness and peripheral curves they were able to provide the patient with a comfortable, effective contact lense which provided greater amounts of corneal changes. This group of doctors who practiced orthokeratology became known as orthokeratologists.

Specific procedures began to develop to systematically reduce the cor-neal curvature and decrease myopia with the result being improved, unaided vision. A series of contact lens changes was employed. Each lens was flatter in fit and would be changed every four to eight weeks. Earlier orthokeratology programs took from two to three years in the 1960s and ‘70s.

The International Orthokeratology Section of the National Eye Research Foundation was founded in 1971. This organization instituted education, control and certification of the practice of orthokeratology or corneal molding. It was important that those doctors who were performing ortho-k be certified as an orthokeratologist to ensure the finest medical approach to vision correction. As improvements in the procedure continued, university studies were conducted with remarkable outcomes in favor of this revolutionary non-surgical procedure. There are several orthokeratologists who should be recognized for their efforts during the pioneering phase of the development. You may view the list in the acknowledgments.

By the 1980s and ‘90s contact lense materials were available that allowed significant amounts of oxygen to pass through the lens. This allowed for much improved corneal health for those wearing contact lenses. These new lenses are called rigid gas permeable contact lenses. At the same time the new materials were being developed for accelerated ortho-k, contact lens labs were using sophisticated computerized lathes to fabricate sophisticated multi- curve lens designs. A growing number of orthokeratologists employed the latest methods of recently developed lenses and materials with remarkable results.

Night wear ortho-K lenses require FDA approval which is now in the late phases of clinical trails. Doctors are not allowed to advertise or promote night wear ortho-k until FDA approvals are completed soon.

When the accelerated corneal molding procedure is completed, and maximum attainable results are achieved, a retainer contact lens is necessary to maintain the improved vision. The retainer contact lens functions much like an orthodontist’s retainer that stabilizes the results of braces.

Orthokeratologists, especially Dr. Richard Wlodyga and Dr. Donald Harris, began researching the new accelerated ortho-K lenses and published the first article Accelerated Ortho-k on this subject in 1992, along with Nick Stoyan of Contex (Contact lens lab). He helped pioneer these lenses and received the first patent for day wear Ortho-k Contact lenses with his airperm material. The goal was to improve the amount of myopic reduction and decrease the time required to remold the cornea. In 1992, with improved multi curve lenses, the Ortho-K doctors began calling the procedure Accelerated Ortho-k. The newer accelerated methods allowed for more change in much less time. Now the program is from one to six months in length (in most cases) as opposed to years needed for earlier techniques.

Today the procedure is well developed and appropriate for thousands of patients who suffer from myopia and astigmatism. Many of the people who want to avoid the risks of surgery (LASIK) are now benefitting from the latest Orthokeratology procedures.