Precision in sight

Equipment developed by USP and a small company allows for rigorous examinations on the curvature of the cornea

Imagem: EDUARDO CESARLuminous ring with seventy-two points for projection onto the patient’s corneaImagem: EDUARDO CESAR

Examinations for tests in the use of contact lenses and for the verification of scarring and of eye distortion after cataract surgery and cornea transplants have gained a new piece of equipment that will make these medical procedures much easier, more precise and less costly in relation to the current equipment. Called a keratometer, this model was developed in an agreement between researchers from the Engineering School of São  Carlos (EESC), the Medical School of  Ribeirão Preto (FMRP), both from the University of São Paulo (USP), and the company Calmed, in the town of São Carlos.

The device, which measures the rays of curvature of the cornea, has already had a patent request made in Brazil, the United States, Europe and Japan. The forecast date for the commercial launch is the first semester of  2005. To this end, Calmed has just completed the signing of a licensing and production agreement with Apramed Aparelhos Médicos, a company in the town of São Carlos that specializes in the manufacture, importing and exporting of ophthalmology equipment. The partnership guarantees a greater industrial infrastructure, and an adequate distribution network for the commercialization of the new equipment, both in Brazil and abroad.

The physicist Liliane Ventura is heading the project for the EESC, where she is a professor, and at the FMRP, as the coordinator of the Ophthalmic Physics Laboratory (LFO). At Calmed, the company of which she was one of the founders, she is coordinating the project that received funding from FAPESP through the Small Business Innovation Research (PIPE) program for the commercial development of the product. She stated that among the advantages of the new piece of equipment is the projection of a luminous ring with seventy-two points of light on the patient’s cornea, in the region of  3 millimeters (mm) of the pupil.

Imported manual keratometers measure a continuous ring of  light on the eye, with great precision, but however the measurement is limited, generally up to twenty-six diopters, or twenty-six  degrees of astigmatism, while the new national equipment measures up to sixty  degrees of astigmatism, a problem coming from the oval shaped cornea that can come about as a consequence of cataract surgery, preventing the perception of contrasts and making reading difficult, by generating images that are unclear, both over short and long distances. Since the machine in not automatic, the measurements made with the manual equipment take much longer. Now the automatic version, which makes up part of auto refractors (measuring myopia, astigmatism and hypermetropia), has only six (6) points of projection on the cornea and has one maximum measurement of twelve (12) degrees of astigmatism.

The Brazilian keratometer also has its particularities in relation to other pieces of equipment of this type. It came about starting from the development of a luminous projection ring of  high precision, invented for adaptation to a Slit Lamp, a common piece of equipment in ophthalmology consulting rooms, used during various types of eye examinations to project light onto the patient’s eyes and to widen its reflection by means of a microscope. The majority of eye clinics use this device along with a manual keratometer separately. One of the goals of the group of researchers was in fact to unite the ring to the Slit Lamp and to integrate this equipment onto a computer for the calculations of the eye measurements that previously were done by different machines. A specific piece of software was developed by Calmed to carry out all of the calculations, measuring the curvature of the cornea with great speed. “The optical part of the Slit Lamp is very efficient. We searched to associate this apparatus to some pieces that would permit us to widen its usage, transforming it into an automatic keratometer, adapting pieces developed specifically during the research, and thus obtaining  a precision instrument that is of low cost”, Liliane explains.

The option for the same degree of speed and precision of the keratometer, which will be manufactured by Apramed, only exists in equipment known as the corneal topographer. They are much more expensive and measure the rays of curvature of all of the surface of the cornea, at around 10,000 different points. This volume of information is much greater. However it is unnecessary since point actions such as the adaptation of contact lenses and other measurements that can be catered for by using a keratometer. The national equipment was developed specifically to measure the cornea?s ray of curvature for the adaptation of contact lenses, although it is also in use for post-operation examinations.

Objective working
The working of the national keratometer is relatively simple. The system makes use of the very light emitted in the form of a slit, permitting the homogenous illumination of the eye. During the examination, two conical surfaces are reflected by way of the continuous points of light of highly reduced size that pass through the ring. This part of the equipment functions as a measuring devise for any surface topography that reflects light, and can also be used as well in microscope surgery.

On projecting the light ring onto the patient’s ocular surface, the Slit Lamp captures the reflection generated and amplifies the image twenty five times. In this manner the evaluation of the curvature rays and any possible deformity is carried out, as a function of the irregularity of the reflected points of light. Next, this amplified image is captured and a piece of software, developed for the project, carries out all of the calculations. The image is also shown on a monitor, with maps and graphics, made available in only three seconds. The screen informs as to how spherical the cornea is, its ray of curvature, focal point and degree of astigmatism.

The success of the development of the equipment is accredited by one of the researchers involved in the project, the ophthalmologist doctor Sidney Julio de Faria and Sousa, the coordinator of the medical part of  LFO, to the project’s multidisciplinary character that involved professionals from different areas such as physics, medicine and engineering.

“Discussions took place between researchers from the two faculties. In this way we have created something unprecedented, efficient, extremely necessary from the clinical point of view, with a guaranteed application and accessible in terms of costs”, says doctor Souza, who is also the clinical director of the Eye Bank at the Hospital das Clinicas in Ribeirao Preto (HCRP-USP), where he coordinated the tests on the apparatus during two and a half years. Until arriving at the final model, four prototypes had been developed. The current version was tested for a year and a half.

In all, four hundred and twenty (420) patients were selected and submitted to the system, including post-operational cases, those of high, medium and low astigmatism among the elderly, children and patients with a cataract and keratoconus, an illness characterized by a cornea in the form of a cone that diminishes considerably the capacity for vision, and which can lead to blindness. The results registered 98% agreement between the new equipment and other equipment currently in use.

The difference in measurement of  2% was due to the fact of a difficulty with the alignment of the optical center of the patient’s eye, demonstrated by some of the commercial equipment. In order to avoid this problem, the researchers developed a device for the fixation of the patient’s gaze. The location of the target on the eye is shown on the computer’s screen, in an amplified manner, which facilitates the exactitude of the positioning of the target for the light during the examination. A device for calibrating, positioned at the location of the Slip Lamp’s focal point, is brought into play on the capturing of the image, so as to maintain the equipment well calibrated. Also, a sensor that indicates the patient’s eye (right or left) that is being measured, was developed during the project. Another innovation is a system for voice generation that emits, in Portuguese or English, the measurements captured by the equipment.

According to Wilson Marcos Mazari, a director at Apramed, the keratometer,  presented in September during the 16th Brazilian Conference on the Prevention of Blindness, in Rio de Janeiro, should be well received both in the Brazilian market and outside of the country. “The production cost has not yet been defined, but  the intention is to make the final price of  the product highly accessible. In order to have an idea of how  much lower the cost might be, one only has to mention the target ring, which can be produced at a cost of  R$ 150.00 per unit, something unthinkable only a short time ago”, he reveals.

Outside of  Brazil, two large companies in this segment have already shown interest in selling the product. “The idea is first to put it on the Brazilian market and then on the international market, beginning with Latin American countries. Another major advantage is that this keratometer can be easily mounted and operated”, he says. Although the national equipment still does not have a selling price tag, the estimate is that it should be commercialized at a price of around US$ 3,000.00, somewhat close to the price of manual keratometers. An automated imported piece of equipment costs around US$ 10,000.00.

The equipment, which still does not have its commercial name defined, is now in the final design phase and its industrial production and commercialization depends on authorization from the National Sanitation Vigilance Agency (Anvisa). Although it is aimed at smaller markets, countries that have the technology in this area should also receive the product. “As this keratometer is a basic instrument for an ophthalmology clinic and as well for the adaptation of contact lenses, the possibilities of taking on projections for the product are high. It is well worth remembering that, in spite of the increase in the number of surgeries that dispense with the use of contact lenses, the cost of this type of operation is still considered high, as well as the fact that surgical intervention does not apply to all cases”, evaluates Liliane.

The trajectory of  the national keratometer began when the researcher received funding, at the time when she was writing her post-doctoral thesis at FMRP, during 1997, for a project through FAPESP’s Young Researchers in Emergent Centers program. “Afterwards the PIPE program made possible not only the financing so that Calmed  could develop the device, but also the university researchers who worked on the project, making possible the placement of the technology on the market. With this support, we managed to do everything much faster and to generate a Brazilian product of  high performance. More than just this, we also created a syntony in the research and development of  technology, extremely important in the area of ophthalmology, in which Brazil can count upon 10% of all of the professionals throughout the world”, she explains.

As well as the two USP laboratories, another institution is also collaborating in the development of the research, by way of the researchers Luimar Cavalcanti de Oliveira and Orlando Di Lorenzo Filho, from the Federal University of Paraíba (UFPB), with the objective of widening the immediate finality of application of the knowledge also gained in the northeast of the country. This is the Ophthalmic Laboratory of UFPB, in the city of João Pessoa, which is giving incentive to the production of ophthalmology equipment for companies that are already established in the region or that might be founded on a short or medium timescale. “The results obtained motivated a partnership with the UFPB for us to form a new unit of ophthalmology instrumentation in the country. The objective is to develop local research that can be applied to the economic reality of the northeast”,  Liliane explains.

The projects
 Automatic measuring system of the rays of curvature of the cornea in a Split Lamp – automatic keratometer in a Split Lamp  (nº 00/13218-4); Modality Small Business Innovation Research (PIPE) program; Coordinator Liliane Ventura Schiabel –  USP/Calmed; Investment R$ 215,878.00 (FAPESP)
2. Ring shaped luminous target for precision measurements of the topography of a spherical and non-spherical reflector surface (nº 03/06208-0); Modality Intellectual Property Support Program (PAPI); Coordinator Liliane Ventura Schiabel – USP/Calmed; Investment R$ 12,500.00  (FAPESP)