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G.L. Spaeth, J.R. Polansky, C. Chen, E. Si, S. Wisov; Evaluating the Course of Glaucoma by Quantitative Grading of the Optic Disc and Visual Field: Effect of the Myocilin Mt.1(+) Variant . Invest. Ophthalmol. Vis. Sci. 2003;44(13):87.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To evaluate applications of quantitative disc and field grading approaches for monitoring the course of glaucoma, and to examine whether information from genotyping for the myocilin TIGR/MYOC mt.1 variant influences the data. Methods: The patients studied (149, average follow-up 15 years) had POAG defined by rigorous criteria requiring at least two definite abnormalities: characteristic disc damage, characteristic field loss, disc or field asymmetry of greater than two stages, intraocular pressure asymmetry of greater than 4mm Hg. Exclusion criteria included patients with end-stage glaucoma (the final two stages). The amount of disc and field damage present on entry and every five years, was measured by using 8-point scales quantifying the amount of damage (Disc Damage Likelihood Scale) (DDLS) and (Field Damage Likelihood Scale) (FDLS). The DDLS and the FDLS gradings were performed separately, without knowledge of each other, or other clinical data. Genotyping was performed separately in a masked fashion. Results: FDLS and DDLS provided independent objective assessments of the course of glaucomatous disease, with a two-step change in either showing a lack of reversals. A combined system defined by a two step change in disc together with at least a one step change in field provided another useful means to define progressive damage. The mt.1(+) variant (-1000 C/G) was present in approximately 15% of the subjects. The progression of glaucoma appeared to be influenced by the presence or absence of this variant in evaluations greater than 10 years in follow up, and was most clearly demonstrated using the combined disc/field system (e.g. using the combined system mt.1(+) vs. (-) patients showed 20% vs. 10% progression in 6-10 years; 63% vs 30% progression in 16-20 years). Mt.1(+) and (-) patients showed no obvious differences of intraocular pressure to explain the findings. Conclusion: The quantitative grading systems described can provide means to consider the clinical course of glaucoma. Patients with POAG who have the TIGR/MYOC mt.1(+) variant may be at greater risk for serious deterioration compared to those without the variant.
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