Korean J Ophthalmol.  2015 Oct;29(5):309-314. 10.3341/kjo.2015.29.5.309.

Choroidal Blood Flow Change in Eyes with High Myopia

• Yang YS
• Koh JW

• KMID: 2363804
• DOI: http://doi.org/10.3341/kjo.2015.29.5.309

Abstract

PURPOSE
To evaluate choroidal blood flow changes in eyes with high myopia according to the pulsatile components of ocular blood flow analysis.
METHODS
A total of 104 subjects (52 males and 52 females) were included in this study. One eye of each participant was randomly selected and assigned to one of four refractive groups, designated as, hyperopes (n = 20; refractive error, > or =+1.00 diopter [D]), emmetropes (n = 28; refractive error, +/-0.75 D), lower myopes (n = 33; refractive error, -1.00 to -4.75 D), and high myopes (n = 23; refractive error, < or =-5.00 D). Components of pulse amplitude (OBFa), pulse volume (OBFv), pulse rate (OBFr), and pulsatile ocular blood flow (POBF) were analyzed using a blood flow analyzer. Intraocular pressure and axial length were measured.
RESULTS
Pulsatile components of OBFa, OBFv, and POBF showed positive correlations with refractive error and showed negative correlations with axial length (r = 0.729, r = 0.772, r = 0.781, respectively, all p < 0.001; r = -0.727, r = -0.762, r = -0.771, respectively, all p < 0.001). The correlations of refractive error and axial length with OBFr were irrelevant (r = -0.157, p = 0.113; r = 0.123, p = 0.213). High myopes showed significantly lower OBFa, OBFv, and POBF than the other groups (all p < 0.001).
CONCLUSIONS
Axial length changes in high myopes potentially influence choroidal blood flow, assuming the changes are caused by narrowing of the choroidal vessel diameter and increasing rigidity of the choroidal vessel wall. These finding explains the influence of axial length on OBFa, OBFv, and POBF, but not on OBFr. Thus, changes in axial length and the possible influence of these changes on the physical properties of choroidal vessels is the mechanism believed to be responsible for putting high myopes at risk for ocular vascular diseases.

Keyword

Choroidal blood flow; High myopes; Pulsatile component of ocular blood flow

MeSH Terms

Adult
*Axial Length, Eye
Choroid/*blood supply
Female
Humans
Male
Myopia/diagnosis/*physiopathology
Regional Blood Flow/*physiology
Young Adult

Figure

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  Fig. 1 Mean value, 95% confidence interval, and range of pulsatile ocular blood flow (POBF) in different groups.

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  Fig. 2 Relationship between refractive error and axial length. D = diopters.

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  Fig. 3 Refractive error correlations. (A) Positive correlation of refractive error with pulse amplitude (OBFa) (r = 0.729, p < 0.001). (B) Positive correlation of refractive error with pulse volume (OBFv) (r = 0.772, p < 0.001). (C) No significant correlation of refractive error with pulse rate (OBFr) (r = -0.157, p = 0.113). (D) Positive correlation of refractive error with pulsatile ocular blood flow (POBF) (r = 0.781, p < 0.001). D = diopters.

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  Fig. 4 Axial length correlations. (A) Negative correlation of axial length with pulse amplitude (OBFa) (r = -0.727, p < 0.001). (B) Negative correlation of axial length with pulse volume (OBFv) (r = -0.762, p < 0.001). (C) No significant correlation of axial length with pulse rate (OBFr) (r = 0.123, p = 0.213). (D) Negative correlation of axial length with pulsatile ocular blood flow (POBF) (r = -0.771, p < 0.001).

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