Purpose To identify factors associated with retinal capillary density as measured with Confocal Scanning Laser Doppler Flowmetry (Heidelberg retina flowmeter (HRF)) in the Thessaloniki Eye Study (TES).
Methods Participants of the TES (age ≥60 years, cross-sectional population-based study) were assessed for active capillary density in the superior and inferior peripapillary retina using the HRF. Pixel-by-pixel analysis was performed to quantify the percentage of zero flow pixels (ZFPs; surrogate for % retinal area with non-active capillaries). Multivariable regression analyses were performed to assess the association of non-active vascular density with ophthalmic and systemic variables. Glaucoma, late age-related macular degeneration and diabetic retinopathy subjects were excluded.
Results 1189 subjects were included in the analysis. Older age (per year) was associated with higher percentage of ZFP in both the superior (slope estimate (SE)=0.0020) and the inferior (SE=0.0019) peripapillary retina (p<0.0001). History of migraine was associated with lower percentage of ZFP (SE=−0.0166) compared with no history of migraine in the superior peripapillary retina only (p<0.05). Higher intraocular pressure ((IOP) per mm Hg) and height (per cm) were associated with higher percentage of ZFP in the inferior peripapillary retina only (SE=0.0012, p<0.05 and SE=0.0005, p<0.05, respectively). The group consuming vegetables one to three times per week compared with the group consuming vegetables at least once a day had higher percentage of ZFP only in the inferior peripapillary retina (SE=0.0080, p<0.05).
Conclusion At a population level, our study revealed associations of older age, higher IOP and taller height with lower active retinal capillary density and of migraine with higher capillary density. Looking further into these associations may provide insight into disease mechanisms.
- ocular blood flow
- heidelberg retina flowmeter (HRF)
- population-based study
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Contributors ND, AH, ALC, MRW, BS and FT conceived and designed the study. ND, PF, EA, TP, AK and FT acquired the data. FY and VK analysed the data. All authors interpreted the data. ND, AH, PF and FT drafted the final manuscript.
Funding Grants from Center for Eye Epidemiology, UCLA, California, USA, grants from Health Future Foundation, Creighton University, Omaha, Nebraska, USA, grants from International Glaucoma Association, UK, grants from Texas Tech University, Texas, USA, grants from Pfizer, New York, USA, grants from Merck and Co, New Jersey, USA, grants from Pharmacia Hellas, Athens, Greece, grants from Novartis Hellas, Athens, Greece, during the conduct of this study.
Competing interests AH would like to disclose that he receives remuneration from CIPLA, AdOM and Shire for serving as a consultant. AH also holds an ownership interest in AdOM and Oxymap. All relationships listed above are pursuant to Indiana University’s policy on outside activities. FT (corresponding author) reports grants from Center for Eye Epidemiology, UCLA, California, USA, grants from Health Future Foundation, Creighton University, Omaha, Nebraska, USA, grants from International Glaucoma Association, UK, grants from Texas Tech University, Texas, USA, grants from Pfizer, New York, USA, grants from Merck and Co, New Jersey, USA, grants from Pharmacia Hellas, Athens, Greece, grants from Novartis Hellas, Athens, Greece, during the conduct of the study; other (advisory board) from Aerie, grants from Pfizer, grants from Thea, grants from Alcon, grants and other (advisory board) from Novartis, grants from Rheon, grants and other (lecture fees) from Omikron, grants from Pharmathen, grants from IDx, USA, other (advisory board) from Zeiss, outside the submitted work. PF would like to disclose that she has contributed as a co-author to the European Glaucoma Society Terminology and Guidelines for Glaucoma 4th edition. The rest of the authors have nothing to disclose.
Patient consent for publication Not required.
Ethics approval The study was approved by the Aristotle University of Thessaloniki Ethics Committee and the Institutional Review Board of the University of California, Los Angeles.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon request.
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