Abstract
PurposeTo investigate the relationship of ocular blood flow (via arteriovenous passage time, AVP) and contrast sensitivity (CS) in healthy as well as normal tension glaucoma (NTG) subjects.DesignMono-center comparative prospective trialMethodsTwenty-five NTG patients without medication and 25 healthy test participants were recruited. AVP as a measure of retinal blood flow was recorded via fluorescein angiography after CS measurement using digital image analysis. Association of AVP and CS at 4 spatial frequencies (3, 6, 12, and 18 cycles per degree, cpd) was explored with correlation analysis.ResultsSignificant differences regarding AVP, visual field defect, intraocular pressure, and CS measurement were recorded in-between the control group and NTG patients. In NTG patients, AVP was significantly correlated to CS at all investigated cpd (3 cpd: r = − 0.432, p< 0.03; 6 cpd: r = − 0.629, p< 0.0005; 12 cpd: r = − 0.535, p< 0.005; and 18 cpd: r = − 0.58, p< 0.001), whereas no significant correlations were found in the control group. Visual acuity was significantly correlated to CS at 6, 12, and 18 cpd in NTG patients (r = − 0.68, p< 0.002; r = − 0.54, p< .02, and r = − 0.88, p< 0.0001 respectively), however not in healthy control patients. Age, visual field defect MD, and PSD were not significantly correlated to CS in in the NTG group. MD and PSD were significantly correlated to CS at 3 cpd in healthy eyes (r = 0.55, p< 0.02; r = − 0.47, p< 0.03).ConclusionRetinal blood flow alterations show a relationship with contrast sensitivity loss in NTG patients. This might reflect a disease-related link between retinal blood flow and visual function. This association was not recorded in healthy volunteers.
Highlights
Glaucoma is one of the leading causes of irreversible blindness in the world [1].Whereas first described in 1857, glaucoma in absence of elevated intraocular pressure, named normal tension glaucoma, remains not sufficiently understood today [2,3,4]
As glaucoma mainly affects the retinal ganglion cells, significant correlations of decreased GC thickness measured via OCT and contrast sensitivity (CS) were reported in glaucoma patients [18]
In neither normal tension glaucoma (NTG) patients nor healthy control subjects was age significantly correlated to CPD (p > 0.14 in all calculations)
Summary
Glaucoma is one of the leading causes of irreversible blindness in the world [1].Whereas first described in 1857, glaucoma in absence of elevated intraocular pressure, named normal tension glaucoma, remains not sufficiently understood today [2,3,4]. Ocular hemodynamics are nowadays often accepted as a critical risk factor in glaucoma, in these patients without elevated IOP [5,6,7,8,9,10]. There are two major issues in the discussion about ocular hemodynamics. Contrast sensitivity (CS) is important in human vision and substantially affects the level of disability experienced by the patient [12,13,14]. It was previously reported that retinal ganglion cells significantly contribute to contrast sensitivity and contrast adaptation [15,16,17]. As glaucoma mainly affects the retinal ganglion cells, significant correlations of decreased GC thickness measured via OCT and CS were reported in glaucoma patients [18]
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