OPTICAL COHERENCE TOMOGRAPHY OF CORNEA AN D ANTERIOR SEGMENT OF THE EYE

Target: The method of optical coherence tomography (OCT) was investiga ted regarding its suitability and limits for measuring the cornea and the anterior segment of the eye. Furthermore, the stromal expansion of thermally induced lesions in the cornea directly after irradiation wa s determined within the scope of the laser thermokeratoplasty (LTK). M aterial and methods: With the experimental scanning OCT system, x-z se ctions of the anterior eye segment were made with an optical resolutio n of about 20 mu m axially and 25 mu m laterally. Freshly enucleated, tonicized porcine eyes were used as model eyes. Thermal lesions were a pplied with a continuously emitting laser diode (lambda=1.86 mu m) and various radiation parameters, Before and after coagulation, the corne a was viewed from limbus to limbus in a central OCT scan and the indiv idual coagulation source was measured, Results: Global and local chang es of the thickness of the cornea as well as the distance between corn ea and lens were measured with high precision. Thermal lesions in thei r expansion can be clearly presented and matching well with the histol ogically stained sections, bur are not as exactly defined at the edges due to the limited optical resolution, as known from histological pre parations. Conclusion: With the OCT method quantitative measuring of t he anterior eye segment can be performed in vitro and with reduced res olutions also in vivo. Due to the qualitatively good correspondence re garding the dimensions of thermal damage of the cornea with histologic ally obtained morphometric results,this method can be used for supervi sion of coagulation directly after LTK as well as for examination of t he individual healing process.