Increasing automation within all areas in everyday life make the application of software systems for administration and services essential. For the past few years, this development has been strongly supported by the Austrian health-care system. The implementation of a chip card system instead of health insurance certificates and the numerous innovations in the IT-supported hospital administration form the base for an efficient and cost-minimizing administration in health-care.

 

The rapid development of computer systems increasingly allows the application of software systems within the medical field. Even today high-capacity computers for image processing and 3D graphics in combination with specialized systems provide a reasonable addition e.g. in medical diagnosis. A basic criterion for the use of such systems in practice is their reliability and an authentic representation of medical data and results respectively, which eliminates errors in interpretation as good as possible. In the application of virtual reality in connection with surgical interventions, the success of an operation is substantially influenced by data obtained from such a system. Detailed graphical visualization enables the surgeon to preoperatively simulate a disease and afterwards, by means of interactive "virtual surgery", plan, check and possibly even correct a surgical procedure in order to achieve the best result.

 

Due to the constantly rising demand of such systems, substantial research in surrounding fields of computer sciences are concerned with the "correct" modeling of a "virtual" human. The goal of this work is to represent the anatomy of the human body as realistically as possible by trying to apply well-known relationships from the mechanics to the anatomy of humans. Complex mathematical models of skeletons, muscles, joints and their graphical, three-dimensional visualization form the basis of an interactive system. The result is a biomechanical model of the human body, which again, finds application in research and study. By systematic studying of such systems, new insight can be derived, integrated into the model and subsequently be used to extend research.

 

The SEE-KID (Software Engineering Environment for Knowledge-based Interactive Eye motility Diagnostics) project tries to connect aspects of biomechanical modeling with methods of modern software engineering. This project is mainly based upon the Orbit™ software system (see www.eidactics.com) and other biomechanical software, however, it tries to extend functionality and supply different modeling aspects within one single computer application.

 

We see SEE++ as replacement or extension to Orbit™ with more clinical relevance while providing essential functionality similar to what Orbit™ offered. The SEE++ software differentiates between biomechanical models and user interfaces and therefore provides an open, flexible and portable basis for further development. Additionally, the "SEE-KID" and "SEE-KID Active Pulley" models have been developed in order to incorporate new anatomic and physiological findings from basic research. Compared to Orbit™, these models also use a different mathematical approach for numerical optimization in order to more reliably solve non-linear problems, a special and important task when simulating the statics of mechanical systems like the human eye.

 

The department of ophthalmology at the convent hospital of the "Barmherzigen Brüder" in Linz, Austria, is the direct partner of the SEE-KID project and has specialized in correcting congenital and acquired eye motility disorders (e.g. strabismus with or without nystagmus), particularly in infants, by e.g. resection or transposition of certain eye muscles. Most of these extraocular muscle surgeries have to be carried out in pre-school age. To avoid a permanent misalignment and a sensory adaptation resulting from it, in individual cases (e.g. fibrosis syndrome) children have to be operated as soon as possible at an early age. Prerequisite for such surgeries is an early diagnosis including a pretreatment e.g. via occlusion (masking the better eye in order to support the weaker eye).

 

For the success of an extraocular eye muscle surgery it is not only important to understand the underlying mechanism of clinical findings, but also to understand the underlying anatomic functional mechanisms in order to avoid wrong or multiple surgical treatments.

 

Such model-supported eye muscle surgeries have been performed at the hospital of the "Barmherzigen Brüder" in Linz, Austria, since 1978. Thus it was also possible to develop new surgery techniques.

 

Especially complicated surgeries have to be planned in detail in the forefront of the actual intervention and appropriate surgery procedures have to be chosen. Up to now it has only been possible to carry out and perfect the process of a surgery directly on the patient. In the case of particularly complicated pathologies, even the experienced surgeon has to rely on documented empirical values, which often leads to multiple treatments until the result is satisfying.

 

The result of our project is a software system (SEE++), which enables physicians to simulate eye motility disorders on the basis of patient measurements and to perform almost all possible surgical treatments interactively. Using a 3D representation of the geometry of the human eye as well as reference points, lever arm lines (the sum of all reference points with the same lever arm) and the relationship of origin and insertion on the surface of the eye or in the orbita ("Functional Topography"), the surgeon can model the disorders as deviations from a non-pathological "healthy" eye. Thus the surgeon can determine the optimal treatment for the patient and plan it in detail.

 

The simulated surgeries are visualized on the computer in a three-dimensional way and in diagrams for comparison with clinical measurements and they are checked for plausibility. In addition, reference points and measured values described above are displayed to the surgeon, enabling better orientation and correct positioning while operating a real patient's eye.