Strabismus occurs in 2 to 4 percent of the population. In the United States, 83,000 strabismus operations are performed annually, and 20 to 50 percent require reoperation. This project will develop clinical diagnostic instrumentation that has the potential of reducing these reoperations by 20 percent. An optoelectronic research instrument has been developed for precisely measuring and analyzing the passive orbital stiffness (length-tension) curves of monkeys. Since 1985, various versions of this instrument have been used successfully to run hundreds of orbital stiffness curves on monkeys in more than 50 experiments. Although very accurate, the current research equipment is too unwieldy, too slow to set up, and too bulky for routine clinical use.It is planned to transform this research instrumentation into a practical, convenient, easy-to-use prototype clinical instrument to permit quantitative forced-duction tests in the operating room. A series of clinical tests on patients undergoing eye surgery will be conducted to begin building a reference database on the relationship of orbital stiffness curves to various forms of strabismus- thyroid ophthalmopathy, multiple reoperations, strabismus after retinal detachment repair, and orbital floor fractures- with the long-term objective of providing the clinician with new diagnostic aids in the form of computerized displays of normal and abnormal ocular length-tension curves.Awardee's statement of the potential commercial applications of the research:Sales of the new instrument will be a modest $250,000 per year (based on an expected worldwide market potential of 1,000 instruments at $2,500 each, selling at the rate of 100 instruments a year), with 45 percent in the export market. Industrial automation applications of the optoelectronic transducer technology is estimated at $2 to 3 million/year.National Eye Institute (NEI)