Peripapillary retinal blood flow in normal tension glaucoma

Aims-To determine if normal tension glaucoma (NTG) patients differ from age matched controls in blood flow to the peripapillary retina, as measured wi th confocal scanning laser Doppler flowmetry (cSLDF; "Heidelberg retinal fl oumetry"). Methods-12 NTG patients and 12 age matched controls were compared using (a) 10 x 10 pixel boxes (the instrument default sample size), taken from the n asal and temporal peripapillary retina, (b) the average from two of these b oxes, and (c) every qualifying pixel within the peripapillary retina. Results-Patients and controls did not differ in blood flow measured using t he default sample from a single 10 x 10 pixel box, placed in either the tem poral or nasal peripapillary retina, or expressed as the average from these two boxes. However, in histograms using every pixel from the peripapillary retina, NTG patients displayed significantly higher percentages of minimal flow pixels (defined as less than one arbitrary unit of flow: 30% v 19%, p <0.01), and significantly lower flow in the 25th, 50th, and 75th percentil e flow pixel teach p <0.05) than did age matched controls. Conclusion-NTG is characterised by reduced blood flow in the peripapillary retina, a result suggesting that blood flow deficits accompany, and perhaps may contribute to, disease development in these patients.