Abstract
Purpose::
To assess whether confocal scanning laser ophthalmoscopy (HRT 3, Heidelberg Engineering) baseline Glaucoma Probability Score (GPS) results are predictive of development of glaucomatous visual field loss in glaucoma suspects.
Methods::
The study included 256 eyes of 256 glaucoma suspects recruited from the longitudinal Diagnostic Innovations in Glaucoma Study (DIGS). Eligible eyes had a reliable standard automated perimetry (SAP) visual field and optic disc stereophotograph within an average of 1.3 months of baseline HRT imaging. Glaucoma suspects were defined based on the presence of suspicious optic disc appearance and/or elevated IOP (> 21 mmHg), associated with normal SAP at baseline. Glaucomatous conversion was defined as development of 3 consecutive abnormal visual fields (PSD with P< .05 or GHT outside normal limits). The association between baseline GPS results and development of glaucoma conversion was investigated by Cox regression models. Multivariate models were adjusted for age, IOP, central corneal thickness (CCT) and PSD. The c index was used to evaluate and compare the predictive abilities of multivariate models.
Results::
Over a 5.8-year average follow-up period, 49 eyes (19.1%) from 256 subjects developed glaucomatous visual field defects. In univariate analysis, age, CCT, PSD, stereophotograph cup-to-disc ratio (CDR) and grading (glaucomatous x non-glaucomatous) and GPS were significantly associated with conversion. After adjusting for age, IOP, CCT and PSD in multivariate models, both GPS and subjective optic disc assessment were predictive of glaucomatous conversion [adjusted hazard ratios (95% CI): 1.24 (1.08 to 1.43) per 0.1 larger, 1.27 (1.04 to 1.55) per 0.1 larger, and 1.97 (0.99 to 3.9) for abnormal grading, respectively]. The c index values for the multivariate models containing GPS, stereophotograph CDR and grading were 0.744, 0.724 and 0.720, respectively. No significant differences were seen among the c indexes for these models (P>0.25 for all comparisons).
Conclusions::
HRT 3 GPS values are predictive of development of visual field loss in glaucoma suspects. A multivariate model incorporating GPS along with other clinically relevant variables performed as well as multivariate models containing subjective assessment of the optic disc in predicting conversion. These results suggest that objective optic disc assessment with the HRT could potentially replace subjective stereo-photograph in evaluating risk of development of visual field loss in glaucoma suspect patients.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • clinical (human) or epidemiologic studies: risk factor assessment • optic disc