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L. Colombo, F. Bertuzzi, E. Rulli, S. Miglior; Correlations Between the Individual Risk for Glaucoma and Rnfl and Optic Disc Evaluations by Means of Oct, Gdx and Hrt in Ocular Hypertensive Patients. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3646.
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To assess the correlation between the 5-year risk of developing POAG (as calculated by the OHTS-EGPS risk calculator) and the optic nerve head and RNFL morphometrical indices as evaluated by Stratus OCT, GDx ECC, HRT III in Ocular Hypertensive (OHT) patients.
Seventy two OHT patients with an untreated IOP between 22 and 32 mmHg in both eyes, an ophthalmoscopically normal optic disc with a c/d ratio asymmetry between the two eyes ≤ 0.2, and a visual field with GHT within normal limits, and normal PSD were enrolled. A comprehensive glaucoma work-up and examination by means of OCT, GDx ECC and HRT III were performed in all of the patients. Probability of developing POAG in 5 years was calculated by means of the OHTS-EGPS risk calculator (RC score), which has been developed by the OHTS-EGPS Collaborative Study Group by taking into account Age, and the mean values of CCT, IOP, PSD and C/D ratio collected in the two eyes. Correlations between the individual risk estimate and the OCT, GDx and HRT parameters were then assessed by regression analysis (exponential and linear), with a statistically significant level of p < 0.01.
Mean age was 62.1 (sd 9.6), mean IOP was 23.4 (sd 2), mean CCT was 569.6 (sd 33.01), mean c/d ratio was 0.38 (sd 0.17), and mean PSD was 1.79 (sd 0.44). The individual risk of the 72 patients ranged between 1.5 and 28.6%, with a mean of 10.2% (sd 6.4). Only OCT RNFL-related parameters showed a statistically significant correlation with the RC score. Average RNFL Thickness had an exponential regression r2 of 0.21 (p<0.0001) and a linear regression r2 of 0.14 (p=0.0012); Superior Average RNFL Thickness had an exponential regression r2 of 0.26 (p<0.0001) and a linear regression r2 of 0.23 (p<0.0001); Nasal Average RNFL Thickness only had an exponential regression r2 of 0.12 (p=0.0031). Neither GDx RNFL-related parameters, nor HRT disc-related parameters showed statistically significant correlations with RC score.
This explorative study showed that the individual risk to develop POAG within 5 years in OHT individuals is statistically significantly correlated with OCT RNFL parameters, but not with GDx RNFL parameters or HRT disc parameters. OCT parameters could explain about 20-25% of the variability in individual RC score. The RC score seems to take into account sub-clinical RNFL thinning shown by the OCT.
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