Methods of optical imaging used in medical diagnostic (with taking the newest diagnostic techniques into consideration in particular) have been presented. Selected optical characteristics of tissues having an influence on the range of the classical methods of the optical imaging have been discussed in detail. The respond to the classical method limitations was to use scanning methods and detection techniques consisting in three-dimensional imaging of tissue structures in real time. A specific eye structure allows the wide using of these techniques in ophthalmology. Such advantages like non-invasiveness, non-contactness and high resolution (guaranteeing the safety of a patient) show a huge success of these techniques. The results of the research (conducted in many research centers) point at the wider application possibility of optical scanning method in medical diagnostic.

The paper discusses the applications of optical coherence tomography (OCT) in the diagnosis of eye disorders, i.e. OCT of the posterior segment of the eyeball and conditions that must be met to use OCT in the studies of the anterior chamber. Limitations ofthe technique and clinical requirements it must satisfy are also described.Keywords: optical coherence tomography -OCT. eye disorders INTRODUTIONOptical imaging techniques are used in medicine essentially to evaluate the morphology of anatomical structures of the human body. Tissues are multicellular structures which differ in the degree oftheir organisation and spectral properties.They constitute scattering media whose measurements fall within a wide range. Additionally, biological media investigated in vivo may undergo changes in the course of the study due to on-going metabolic processes. Also important is the geometry ofthe structure, the effect of surrounding tissues and natural motion produced by respiration, heart beat or muscle tremor. In most cases, these factors are considered the sources of interference directly affecting the quality of imaging. With special techniques, however, some of these phenomena may be actually used for the purposes ofimaging ofthe internal structures ofthe human body. Optical coherence tomography (OCT) is such a technique.In ophthalmology, OCT allows imaging ofinfraocular structures characterized by a moderate scattering coefficient. The method of white light interference is used in the measurements. The use of lowcoherence light sources allows the precise localization of the study area. Linear scanning provides information about scatter changing with the depth of tissue. Simultaneous transverse scanning produces two-dimensional optical tomograms ofinfraocular structures [1, 2].OCT scanners use light sources at 0.6 -1.5 pm. At this range, scatter in the tissue exceeds absorption and the depth of penetration increases up to 10 mm.In a healthy eye, the following are radiolucent in the visible range and the near infrared range: the cornea, anterior chamber, lens and the vitreous fluid. The retina, with its complex anatomical structure and composed ofmany layers, is partially translucent.Studies ofthe retina are the most common application of OCT in ophthalmology, but scans of other eye structures, such as the cornea, anterior angle, iris or lens ,areequally valuable diagnostic aids.

The reflection, absorption and scattering influence on turbid structure has been discussed. The influence of transverse scanning method on geometrical deformations as well as issues of thickness absolute measurements and refractive index evaluation methods has been analyzed. A number of phenomena which may be the artefact source and the cause of tomogram incorrect interpretation have been pointed out.