PERIMETRIC PROBABILITY MAPS TO SEPARATE CHANGE CAUSED BY GLAUCOMA FROM THAT CAUSED BY CATARACT

We describe a new method for analysis of change in glaucomatous visual fields with the object to differentiate between changes caused by gla ucoma from those caused by cataract, New pattern deviation change prob ability maps were developed from a prospectively collected glaucoma ma terial and designed to be sensitive to changes in localized field loss , but to be unaffected by media-induced perimetric change. We compared the new change probability maps with the commercially available total deviation change probability maps in series of Humphrey perimetric te sts in a glaucoma material of 43 eyes of 35 patients, who had undergon e cataract surgery, When using the total deviation maps, considerable differences were seen between fields obtained before and after catarac t surgery. Much smaller differences were seen when using the new chang e probability maps, that almost eliminated the common and disturbing e ffect of increasing cataract, This new tool could be of considerable h elp in differentiation between progressive glaucomatous visual field l oss and deterioration caused by increasing media opacities.