Abstract
Purpose.:
To examine the influence of age on systolic (systOAP) and diastolic (diastOAP) blood pressure in the ophthalmic artery (OA) measured by a new contact lens dynamometer (CLD).
Methods.:
In a prospective cross-sectional clinical trial, 106 eyes of 106 patients (58 women, 48 men) were examined. A nearly uniform age distribution was achieved by recruiting subjects in seven age groups, with at least 12 in each decade. Blood pressure in the OA was measured with a new CLD. Arterial blood pressure at the upper arm was measured by cuff, according to the Riva-Rocci (RR) method. Main outcome measures were: SystOAP and diastOAP in the OA and systolic (systRR) and diastolic (diastRR) pressures in the subclavian artery.
Results.:
The blood pressures showed the following linear regression equations in association with age: systRR (mm Hg) = 115 + 0.45 × age (years) (R = 0.50; P < 0.00001); diastRR (mm Hg) = 72 + 0.28 × age (years) (R = 0.42; P < 0.00001); systOAP (mm Hg) = 61 + 0.93 × age (years) (R = 0.74; P < 0.0001); and diastOAP (mm Hg) = 44 + 0.37 × age (years) (R = 0.57; P < 0.0001).
Conclusions.:
The relative slopes of the regression lines relating age to diastolic and systolic pressures are steeper in the ophthalmic than in the subclavian artery, indicating that the pressures in the ophthalmic artery increase faster with age than do the associated pressures in the subclavian artery, as measured by the standard sphygmomanometry. This phenomenon may be explained by progressive stiffening of the walls in the carotid and ophthalmic arteries. The effect of age should be taken into account whenever interpreting ophthalmodynamometric measurements for clinical diagnostic purposes.
Ophthalmodynamometry is a method of measuring blood pressure in the ophthalmic artery.
1 –3 From the biophysical point of view ophthalmodynamometry is accomplished via iatrogenic elevation of intraocular pressure (IOP) by the application of force on the globe, allowing dynamic observation of the pulsation of vessels entering and exiting the eye at the optic disc. Usually in ophthalmodynamometry the arterial pressures are measured. However, it is also possible but not widely known that the venous pressure can be measured as described by Meyer-Schwickerath et al.
4 Recent results showed that increased pressure in the central retinal vein may play a role in the pathogenesis of glaucoma.
5 –9 Initial attempts to use ophthalmodynamometry clinically involved methods of determining incremental IOP increase by using compressive spring loading
3 or sclera-deforming suction cups.
10 The level of the artificially elevated IOP was correlated experimentally with the applied force, and conversion tables were established. From these tables, the force needed to initiate the pulsation was converted to IOP.
11 As these techniques were often difficult to perform and the use of correlation tables was cumbersome and introduced potential sources of error, most have been almost abandoned in clinical practice. More recently introduced contact lens methods applying mechanical force and semiautomated pressure measurement
12,13 failed to gain favor and were generally considered too cumbersome.
14 These techniques were predominantly used as diagnostic tests in suspected carotid artery stenosis, until they were superseded by the advent of Doppler ultrasound sonography.
An important practical advance from the physical point of view was the Smartlens (ODC Ophthalmic Development Company, Zürich, Switzerland), the first electronic contact lens dynamometer (CLD),
15,16 which allowed direct measurement of artificially elevated IOP. Even this instrument required substantial expertise and was not widely adopted clinically.
Recently, a new electronic CLD was introduced that allows more straightforward application of ophthalmodynamometry in clinical practice. Jonas et al.
17 –32 have demonstrated the potential of this new CLD in the diagnostics of circulatory diseases of the eye, orbit, and brain. The purpose of the present study was to examine the effect of age on measurements obtained with this new electronic CLD.
In this prospective clinical trial, 106 volunteers (
Table 1) were included. Each subject signed an informed consent before entering the study. The study was performed in accordance with the Declaration of Helsinki and was approved by the institutional ethics committee of the Medical Faculty of the University of Dresden.
Table 1. Characteristics of the Participants
Table 1. Characteristics of the Participants
Age Group (y) | n | Sex F/M | Age (y) | Systemic Blood Pressure before CLD |
Systolic (mm Hg) | Diastolic (mm Hg) |
Min | Med | Max | Min | Med | Max | Min | Med | Max |
10–19 | 15 | 9/6 | 14 | 18 | 19 | 106 | 122 | 139 | 61 | 73 | 80 |
20–29 | 15 | 8/7 | 22 | 24 | 27 | 101 | 118 | 139 | 59 | 71 | 80 |
30–39 | 15 | 8/7 | 30 | 30 | 35 | 104 | 125 | 163 | 68 | 80 | 103 |
40–49 | 17 | 10/7 | 40 | 43 | 49 | 114 | 138 | 167 | 72 | 88 | 97 |
50–59 | 15 | 8/7 | 50 | 54 | 59 | 108 | 133 | 175 | 66 | 84 | 114 |
60–69 | 17 | 10/7 | 60 | 66 | 69 | 119 | 139 | 173 | 74 | 82 | 104 |
>69 | 12 | 5/7 | 70 | 73 | 81 | 136 | 146 | 174 | 74 | 87 | 113 |
Exclusion criteria were diabetes mellitus, arterial hypertension, cardiovascular diseases, peripheral arterial and venous diseases, all types of glaucoma, eye surgery (except phacoemulsification more than 3 months ago), circulation diseases of the eye and the brain, and systemic therapy with calcium channel blockers and/or β-blockers.