OCT applications in contact lens fitting.

Optical Coherence Tomography (OCT) is a noninvasive, high-speed, high-resolution imaging technology based in the Michaelson interferometry. A near-infrared light beam is used to register the intensity variations for the light backscattered on each sample layer. Due to the high repeatability on corneal measurements, spectral domain OCT (SD-OCT) is the gold standard when talking about in vivo, non-invasive anterior segment imaging. Changes in the morphology of various ocular surfaces such as the cornea, conjunctiva, limbus or tear film with soft (SCL), rigid, corneal or scleral lens (SL) wear can be described by OCT measurements. For instance, evaluation of the corneoscleral region is essential on SL fitting. For orthokeratology lenses central epithelial thinning and peripheral thickening and their regression could be quantified with OCT after Ortho-K lens wear. Blood vessel compression on the landing zone as well as vault thickness and fluid reservoir (FR) turbidity could be imaged with OCT. Tear film evaluation on contact lens wearers is essential because its use could lead to variations on the biochemical components in tears. Changes in tear meniscus dynamics and several parameters such as volume (TMV), tear meniscus height (HMT) and turbidity could be determined with OCT and positively correlated with the instillation of different ophthalmic solutions with Non-Invasive Break Up Time (NIBUT) and Schirmer test values. This manuscript shows the increasing applicability of OCT technology for the in vivo characterization of contact lens fitting and interaction with the ocular surface in a faster, safer and non-invasive way. Future research will still allow exploring OCT imaging to its full potential in contact lens practice, as there is still a significant amount of information contained in the images that are not yet easy to extract, analyze and give clinical value.