Scientists have been constantly pursuing newer
tests to diagnose Glucoma. Glaucoma is an incurable condition of the eye and if left
untreated can cause blindness and once it effects the vision - this cannot be
restored. It is the second leading cause of blindness in the world - according
to the World Health Organization.
Recently scientists they have been combining
visual field and imaging data, utilizing the anatomical arrangement of retinal
ganglion cells to diagnose the condition more accurately.
In a recent study by Michael V Boland, Assistant
Professor of Ophthalmology at The Wilmer Eye Institute, Baltimore, data from
1499 eyes of glaucoma suspects and 895 with confirmed glaucoma eyes was
identified to be studied. All the subjects underwent standard automated
perimetry and Heidelberg Retinal Tomograph (HRT) imaging. The structure
function index (SFI) was defined in three steps by a new technique combining
the above two tests. The data was studied to study the following:-
the probability that each visual field point is abnormal.
the probability of abnormality for each of the six HRT optic disc sectors,
combine those probabilities with the probability that a field point and disc
sector are linked by ganglion cell anatomy.
Then by using receiver operating characteristic
(ROC) analysis, the SFI was compared to the HRT and visual field.
Researchers noticed during the study that the SFI
produced an area under the ROC curve (0.78) that was quite close to that for
both visual field mean deviation and pattern standard deviation. Also, it was
larger than that for a normalized measure of HRT rim area. The cases
categorized as glaucoma by the various tests were significantly
non-overlapping. The SFI still clearly identifying those with severe disease,
based on the distribution of test values in the population with mild disorder.
In a concluding note, authors summed up by saying
that the SFI reflects the typical clinical diagnosis of glaucoma by combining
optic nerve structure and function. While doing so, it identifies a separate
subset of patients with either visual field testing or optic nerve head imaging
alone. Analysis of prospective data will allow researchers to identify whether
the combined index of structure and function can provide an improved standard
for glaucoma diagnosis.