Keratograph

Keratograph is a family of diagnostic instruments used in ophthalmology and optometry for corneal topography and ocular surface assessment. Developed by Oculus Optikgeräte GmbH, these devices combine Placido disk-based corneal topography with infrared imaging to evaluate the anterior corneal surface, tear film, and, in newer models, the meibomian glands of the eyelids.

Models in the Keratograph line, such as Keratograph 4 and Keratograph 5M, vary in capabilities. The core function is to generate maps of corneal curvature through analysis of reflected Placido rings, providing visual topography and quantitative keratometry data. The 5M model adds meibography to image the meibomian glands and offers non-invasive tear film assessments, including tear film break-up time measurements.

Operation and outputs: during examination, the device projects infrared and visible light patterns onto the eye. Reflections are captured and processed to create corneal topography maps. In the tear film analysis mode, infrared imaging assesses tear film stability and break-up time, aiding dry eye evaluation. Meibography produces images of the meibomian glands to help diagnose meibomian gland dysfunction.

Clinical uses and scope: Keratographs are widely used for screening and monitoring conditions affecting the ocular surface, including keratoconus risk assessment, dry eye disease, and preoperative planning for refractive or cataract surgery. They offer a non-contact, rapid, integrated approach to evaluating corneal shape, tear film quality, and eyelid gland status in a single session.

Limitations: as Placido-based systems, they primarily assess the anterior corneal surface and tear film; posterior corneal structures and certain surface artifacts may require additional imaging modalities.