Human ocular surface microcirculation quantified by in vivo computer assisted video microscopy and diffuse reflectance spectroscopy

Anne Kari Kvernebo; Morten Carstens Moe; Liv Kristin Wikslund; Luigino Capone; Liv Drolsum; Knut Kvernebo

doi:10.1016/j.exer.2022.109232

Human ocular surface microcirculation quantified by in vivo computer assisted video microscopy and diffuse reflectance spectroscopy

Exp Eye Res. 2022 Nov:224:109232. doi: 10.1016/j.exer.2022.109232. Epub 2022 Aug 31.

Authors

Anne Kari Kvernebo¹, Morten Carstens Moe², Liv Kristin Wikslund³, Luigino Capone⁴, Liv Drolsum², Knut Kvernebo⁵

Affiliations

¹ Department of Ophthalmology, Oslo University Hospital, Postboks 4950 Nydalen, 0424, Oslo, Norway; Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, P.O. box 1171 Blindern, 0318, Oslo, Norway; The Circulation Laboratory, Department of Cardiothoracic Surgery, Oslo University Hospital, Postboks 4950 Nydalen, 0424, Oslo, Norway. Electronic address: b24427@ous-hf.no.
² Department of Ophthalmology, Oslo University Hospital, Postboks 4950 Nydalen, 0424, Oslo, Norway; Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, P.O. box 1171 Blindern, 0318, Oslo, Norway.
³ Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, P.O. box 1171 Blindern, 0318, Oslo, Norway; The Circulation Laboratory, Department of Cardiothoracic Surgery, Oslo University Hospital, Postboks 4950 Nydalen, 0424, Oslo, Norway; Ostfold Hospital Trust, Gralum, Norway.
⁴ ODI Medical AS, Oslo, Norway.
⁵ Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, P.O. box 1171 Blindern, 0318, Oslo, Norway; The Circulation Laboratory, Department of Cardiothoracic Surgery, Oslo University Hospital, Postboks 4950 Nydalen, 0424, Oslo, Norway; ODI Medical AS, Oslo, Norway.

PMID: 36055389
DOI: 10.1016/j.exer.2022.109232

Abstract

Non-invasive imaging techniques are increasingly used to objectively quantify anterior segment structures of the eye. In this study, we apply the novel oxygen delivery index (ODIN) concept that, quantifies microvascular capacity for oxygen delivery, to the ocular surface in healthy humans. The purpose of the study was to test the applicability of the technologies used for data acquisition from the human ocular surface. We also validated whether the ODIN concept has sufficient sensitivity to detect and differentiate between microvascular structure and function in limbal and bulbar conjunctiva. Multiple ocular surface measurements using computer-assisted video microscopy (field of view: 1.6 mm × 0.9 mm) and diffuse reflectance spectroscopy (measuring volume: ∼0.1 mm3) were obtained from limbal and bulbar conjunctiva in 20 healthy volunteers. Three parameters were extracted during analyses: Functional capillary density, capillary flow velocity, and microvascular oxygen saturation. Functional capillary density was higher at limbus than in bulbar conjunctiva (11.2 ± 1.8 c/mm versus 5.2 ± 1.2 c/mm, p < 0.01), and microvascular oxygen saturation was lower at limbus (77 ± 8%) as compared to bulbar conjunctiva (89 ± 6%), p < 0.01. More than 80% of scored capillaries had continuous blood flow and no difference was seen between the recording sites (p = 0.68). In conclusion, the ODIN concept is applicable for the assessment of human ocular surface microvascular function and has sufficient sensitivity to detect increased capillary density and oxygen extraction at limbus as compared with bulbar conjunctiva.

Keywords: Capillaries; Conjunctiva; Diffuse reflectance spectroscopy; Imaging technique; Limbus; Microcirculation; Microvascular oxygen saturation; Video microscopy.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Computers
Conjunctiva* / blood supply
Humans
Microcirculation / physiology
Microscopy, Video
Oxygen*
Spectrum Analysis

Substances

Oxygen