[Development of non-invasive clinical examination methods for the anterior segment of the eye and their clinical significance].

UNLABELLED: 1.

PURPOSE: Slit-lamp microscopy is a principal ophthalmic clinical method, because it provides microscopic findings of the anterior segment of the eye noninvasively. Its findings, however, are qualitative and there are large inter-observer variations in their evaluation. Furthermore, slit-lamp microscopy provides morphological findings, but a functional evaluation is difficult. We developed two novel methods that establish a qualitative methodology of the slit-lamp microscope and the pathophysiology of the anterior segment of the eye. One is the flare-cell photometer to evaluate flare and cells in the aqueous humor of the eye and the other is an immunohistochemical examination method using tear fluid to evaluate ocular surface disorders. The comprehensive evaluation of these studies is herein overviewed. 2. INNOVATION OF THE FLARE-CELL PHOTOMETER AND ITS CLINICAL SIGNIFICANCE: The breakdown of the blood-aqueous barrier (BAB) causes an increase in protein (flare) and leakage of blood cells (cell) into the aqueous humor of the eye and the severity of BAB breakdown has a positive correlation with the intensity of flare and cells. The flare and cells in the aqueous can be observed qualitatively by slit-lamp microscopy. These findings are primarily distinguished in optics by light scattering. Therefore, detection of the intensity of light scattering due to flare and cells can evaluate the BAB function. The flare-cell photometer comprises 3 novel components: a laser beam system as an incident light, a photomultiplier to detect scattered light intensity and a computer-assisted system to operate the whole system and analyze detected scattered light signals due to flare and cells. The instrument enables us to quantitatively analyze the flare and cells non-invasively and accurately with a wide dynamic measurement range, resulting in a repeated examination of each individual case. It also enables the evaluation of inflammation in the aqueous not only postoperatively but also in endogenous uveitis, evaluation of the effects of anti-inflammatory drugs on BAB and evaluation of aqueous humor dynamics. Furthermore, repeating the examination can minimize inter-individual variations and reduce the number of animals in animal experiments. 3.

PATHOPHYSIOLOGICAL EVALUATION METHODS OF OCULAR SURFACE USING TEAR FLUID: Sampling of tears can be performed noninvasively, but the obtainable volume is limited. Therefore, a determination of targeting biomarkers and a development of their micro-volume analysis methods play a crucial role in pathophysiological studies of the ocular surface. Targeting biomarkers should be determined according to the various specified bioactive substances such as eosinophil cationic protein (ECP), cytokines and others. A number of microvolume analysis methods, such as chemiluminescent enzyme immunoassay, immunochromatography, micro-array system and polymerase chain reaction method are used. Objective disorders in the studies include allergic conjunctivitis and infectious diseases such as herpetic keratitis. Quantitative evaluation methods for ECP concentration, antigen-specific secretory IgA in allergic diseases and herpetic keratitis, herpes simplex virus-DNA and cytokine and chemokine profile in tear fluid sampled by filter paper method were investigated. We developed a clinically applicable quantitative immunochemical method for ECP concentration in tear fluid. The results revealed that tear fluid analysis using the above mentioned methods is a clinically useful to investigate the pathophysiology of the ocular surface. 4.

CONCLUSION: Laser flare-cell photometer and tear fluid analysis are potent clinical quantitative methods to investigate the pathophysiology of the anterior segment of the eye.