Correlation between structure/function and optic disc microcirculation in myopic glaucoma, measured with laser speckle flowgraphy.

Naoko Aizawa,Toru Nakazawa,Kazuko Omodaka,Yu Yokoyama,Yukihiro Shiga,Hiroshi Kunikata

doi:10.1186/1471-2415-14-113

Abstract

BackgroundIt is difficult to identify glaucoma in myopic eyes because the configuration of the optic disc varies; yet it is important clinically. Here, we used laser speckle flowgraphy (LSFG) to measure mean blur rate (MBR), representing optic disc microcirculation, and assessed its ability to identify glaucoma in eyes with myopic optic discs.Methods129 eyes (normal disc: 21 eyes; myopic disc: 108 eyes) were enrolled. The eyes were classified as normal or mildly, moderately, or severely glaucomatous with standard automated perimetry (SAP). We determined the relationship between optic nerve head (ONH) MBR, measured with LSFG, mean deviation (MD), measured with SAP, and circumpapillary retinal nerve fiber layer thickness (cpRNFLT), measured with optical coherence tomography (OCT).ResultsONH MBR and cpRNFLT decreased significantly with the severity of glaucoma. MBR was significantly correlated with cpRNFLT and MD (r =0.65 and r =0.63, respectively). A multiple regression analysis revealed that MBR and cpRNFLT were independent factors indicating glaucoma severity. A logistic regression analysis revealed that MBR and cpRNFLT were also independent factors indicating the presence of glaucoma. In a receiver operating characteristic (ROC) analysis, MBR and cpRNFLT could both differentiate between normal and glaucomatous eyes (MBR area under the ROC curve: 0.86, with a cut-off score of 24.0 AU).ConclusionThese results suggest that in addition to cpRNFLT, non-invasive and objective LSFG measurements of MBR may enable the identification of glaucoma and the classification of its severity in eyes with myopic optic discs.

Highlights

It is difficult to identify glaucoma in myopic eyes because the configuration of the optic disc varies; yet it is important clinically
There were no significant differences in age, sex, SBP or Systolic and diastolic blood pressures (DBP) among any of the groups, including the normal eyes, but there were significant differences in Intraocular pressure (IOP), spherical equivalent, mean deviation (MD), circumpapillary retinal nerve fiber layer thickness (cpRNFLT) and mean blur rate (MBR)
There were no significant differences in age, sex, SBP, DBP, hypertension medication, topical glaucoma medication or IOP among the myopic groups but there were significant differences in spherical equivalent, MD, cpRNFLT and MBR

Summary

Introduction

It is difficult to identify glaucoma in myopic eyes because the configuration of the optic disc varies; yet it is important clinically. We used laser speckle flowgraphy (LSFG) to measure mean blur rate (MBR), representing optic disc microcirculation, and assessed its ability to identify glaucoma in eyes with myopic optic discs. The development of spectral domain optical coherence tomography (SD-OCT) has enabled ophthalmologists to quickly and measure the average thickness of the circumpapillary retinal nerve fiber layer (cpRNFLT). This has been reported in Recent innovations in laser speckle flowgraphy (LSFG) have allowed us to monitor changes in optic disc microcirculation, represented as mean blur rate (MBR), over time, at the same site and in the same eye. Though the pathogenesis of glaucoma in eyes with myopic optic discs remains unclear, as it does in normal tension glaucoma, decreased ocular blood flow [13], including optic nerve microcirculation, is considered to be a promising candidate, in addition to mechanical stress, oxidative stress and decreased axonal flow

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