Abstract
Purpose: :
To compare parapapillary blood flow and its relationship with optic disc phenotype in open-angle glaucoma (OAG) patients.
Methods: :
Parapapillary blood flow was measured in a randomly selected eye of 81 OAG patients by Heidelberg Retinal Flowmetry (HRF) after a medication washout period of 15 days. Each eye was scanned 2 times to acquire perfusion maps of the superior and inferior regions. Scanning Laser Doppler Flowmetry software was then used to subdivide and analyze data by quadrant (inferotemporal, superotemporal, inferonasal and superonasal) for further analysis. Disc phenotypes (senile sclerotic, myopic, focal ischemic, or concentric) were determined by 2 independent graders who reviewed stereophotography. Kappa test was used to determine interobserver agreement. Adjudication of phenotype was performed by a third experienced grader. Mean blood flow was compared by diagnosis and phenotype. Results were corrected for age and gender.
Results: :
13/81 OAG patients were excluded for having mixed phenotypes. The remainder was classified as 41 concentric, 13 focal ischemic, 6 myopic, 8 senile sclerotic. Kappa score for inter-observer agreement was 0.82. A comparison was made between patients with concentric (41) versus non-concentric phenotypes (27). There was no significant difference in global parapapillary blood flow between groups (Concentric Mean 273.8 au, CI 260.1 - 287.4 au, Non-concentric Mean 286.7 au, CI 266.3 - 307.0). Temporal flow was significantly higher than nasal flow in the concentric group, but not in the non-concentric group (Concentric Temporal mean 296.7 au, CI 277.6 - 315.8, nasal mean 249.0 au, CI 228.7 - 269.3 au, F ratio 5.70, P < 0.001, after Tukey test for post hoc analysis). The results remained significant after adjusting for age and gender.
Conclusions: :
In this sample, global parapapillary blood flow is similar in different disc phenotypes. Patients with concentric phenotypes have significantly greater flow temporally than nasally whereas those with non-concentric phenotypes do not. This may suggest regional blood flow is affected differently in different phenotypes of glaucoma.
Keywords: imaging/image analysis: clinical • optic flow