Complex sentence: While in Paris, he invented a keratometer with Dr. Louis Émile Javal that was to become known as the Javal-Schiøtz ophthalmometer, an optical instrument used to measure the curvature of the anterior corneal surface.
Split into simpler sentences: While in Paris, he invented a keratometer with Dr. Louis Émile Javal, that was to become known as the Javal-Schiøtz ophthalmometer. This is an optical instrument used to measure the curvature of the anterior corneal surface.