Abstract
Purpose: :
To investigate the ability of peripapillary atrophy (PPA) parameters obtained by optic disc stereophotography (ODP) to differentiate glaucomatous optic nerve heads from normal ones.
Methods: :
Sixty-five eyes of 65 patients who all had PPA were examined (35 open angle glaucoma (OAG) and 30 normal subjects). Disc area, cup area, rim area, vertical cup to disc (CD) ratio, CD area ratio, PPA area, zone beta area and zone alpha area were obtained by ODP using intrinsic algorithms. The Receivers operating characteristic (ROC) curves were used to compare the abilities of PPA parameters with those of disc parameters in detecting perimetric glaucoma.
Results: :
PPA measurements obtained by ODP showed good intra-observer repeatability (ICC>0.997). Vertical CD ratio (VCD), zone beta area, area zone-beta to PPA ratio and area zone-beta to disc ratio were significantly larger in OAG (P < 0.05), whereas zone alpha area and rim area were significantly larger in normal group (P < 0.05). Among PPA parameters area zone-beta to PPA ratio was significantly correlated with MD (r=-0.431) and PSD (r=0.411). In differentiating OAG from normal group, VCD show best area under the ROC curve value of 0.929 and this was followed by area PPA to disc ratio (0.786), area zone-beta to PPA ratio (0.760) and zone beta area (0.733).
Conclusions: :
The PPA measurement obtained by ODP was reproducible and can be a useful additional tool to differentiate OAG from normal. The area ratio of zone-beta to PPA seems to be well correlated with severity of visual field defect.
Keywords: optic disc • imaging/image analysis: clinical • detection