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.
AdvertisementIn 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:-
1) calculate the probability that each visual field point is abnormal.
2) calculate the probability of abnormality for each of the six HRT optic disc sectors,
3) and 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.
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