Use of Optical Coherence Tomography in Anterior Segment of the Eye

OCT is a useful tool in examining the anterior segment of the eye at microscopic resolution with the aid of the newly developed slit-lamp adapted OCT system or the hand held probe OCT or the real-time OCT.It can be helpful in to image and measure complex details of corneal pathologies. Corneal thickness measurements by OCT can prove therapeutic control in refractive laser surgery. It is important to control and improve photorefractive laser treatment, and may offer the possibility to give new information about corneal wound healing after these procedures. OCT may also be able to deliver more information about wound healing processes in the cornea after photothcrapeutic keratectomy (PTK) which is performed in patients with recurrent epithelial defects or ptreygium. With the existing OCT system it is also possible to perform topographical measurements of the cornea, analyze corneal curvature and calculate corneal refraction.OCT is helpful in diagnosis and monitoring of various corneal diseases such as microbial keratitis, corneal and scleral melts, Fuchs Endothelial Dystrophyand pellucid marginal degeneration.OCT is of value in studying biometric modifications of the anterior segment with accommodation and age and determines possible applications in areas of anterior segment surgeries, particularly implantation of refractive lenses. The width of the anterior chamber angle is an interesting value, because it determines the risk for acute angle closure glaucoma. Also structural changes in the chamber angle like fibrotic scar formation, or new vessels growth can cause a raise in intraocular pressure and may be detected earlier by OCT. Clinical examination and classification of the chamber angle is routinely performed by direct visualization using a gonioscopy lens. The classification according to Shaffer or Spaeth is widely used, but depends on the experience and the estimation of the individual examiner.AS-OCT has been reported to enhance visualization of iridocorneal angle anatomy, and it may also be useful in identifying the position and patency of shunts that are difficult to visualize when corneal clarity is reduced.OCT allow non contact accurate measurement and three-dimensional characterization of iris lesions.OCT imaging of the lens, capsular bag as well as anterior vitreous can be done within the pupillary area. Also OCT shows its benefits in cataract grading and after cataract surgeries. It can assess capsule closure, intraocular lens calcification, capsular block syndrome and posterior capsule opacity.