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F.A. Medeiros, C. Bowd, L.M. Zangwill, P.A. Sample, R.N. Weinreb; Agreement Between Stereophotographic and Confocal Scanning Laser Ophthalmoscopy (CSLO) Estimates of Cup/Disc Ratio: Effect on a Predictive Model to Estimate the Risk of Conversion From Ocular Hypertension to Glaucoma . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3414.
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© ARVO (1962-2015); The Authors (2016-present)
In a previous study, we developed and validated a predictive model to estimate the risk of conversion from ocular hypertension to glaucoma based on the results of the Ocular Hypertension Treatment Study (OHTS). The previously validated model incorporates 6 factors: age, intraocular pressure (IOP), central corneal thickness (CCT), pattern standard deviation (PSD), stereophotograph estimates of vertical cup/disc (C/D) ratio and diabetes mellitus. In the current study, we evaluated whether the incorporation of Confocal Scanning Laser Ophthalmoscopy (CSLO) estimates of C/D ratio into the predictive model, instead of photographic vertical C/D ratio, would produce comparable estimates of risk.
Fifty–nine patients with ocular hypertension were included from the Diagnostic Innovations in Glaucoma Study (DIGS). All patients had elevated IOP in both eyes (>22 mmHg), normal visual fields on standard automated perimetry, and normal optic discs as evaluated by stereophotographs. All patients underwent CSLO imaging (Heidelberg Retina Tomograph II) within 6 months of stereophotographs. HRT II parameters evaluated were vertical C/D ratio, linear C/D ratio and C/D area ratio. The agreement between stereophotograph and HRT II estimates of C/D ratio was evaluated. Next, the effect of using HRT II estimates on the predictive model was assessed.
There was good correlation between HRT II and stereophotographic estimates of C/D ratio (r ranging from 0.76 to 0.78). For the parameter with best correlation (linear C/D ratio), the difference from stereophotograph estimates of C/D ratio was within 0.2 in 95% of the patients. When incorporated into the predictive model, estimates of risk using the HRT II parameter linear C/D ratio were highly correlated to those obtained using stereophotographs (r = 0.97). The difference between risk estimates using the two models was within 5% for 56 (95%) patients and within 10% for all patients.
HRT II and stereophotograph estimates of C/D ratio can be used interchangeably when incorporated into a predictive model to estimate the risk of conversion from ocular hypertension to glaucoma. Use of HRT II estimates along with the other risk factors can provide an objective assessment of the risk for development of glaucoma in ocular hypertensive subjects.
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