title: [Contact lens dynamometry influences the systemic blood circulation: clinical significance].
abstract: BACKGROUND
  The diastolic and systolic pressure in the ophthalmic artery (OAPdia, OAPsys) as well as the venous pulsation pressure (VPP) can be determined by contact lens dynamometry (CLD). With these parameters, carotid artery stenosis, ocular perfusion, e.g., in glaucoma patients and the cerebrospinal pressure can be examined indirectly. In the underlying study comparative data were collected and it was investigated to what extent CLD itself leads to changes of the systemic blood pressure.
  
  
  METHODS
  In the course of a prospective trial CLD was performed in 162 eyes of 81 healthy volunteers (mean age 41.0 ± 17.3 years). VPP, OAPdia and OAPsys were measured. A mean was calculated from 5 single readings. Directly before and after CLD automated blood pressure measurements according to Riva-Rocci (RR) and the heart rate were obtained in both arms.
  
  
  RESULTS
  In the entire group, the mean VPP was 21 ± 9 mmHg on the right side and 19 ± 8 mmHg on the left side. The mean OAPdia was 60 ± 14 mmHg on the right and 67 ± 14 mmHg on the left side. The mean OAPsys was 91 ± 17 and 101 ± 21 mmHg, respectively. The mean variation coefficient from 5 single readings was 13/16 % for VPP (right/left), 7.4/8.2 % for OAPdia and 6.2/6.2 % for OAPsys. The difference between right and left eyes concerning OAPdia and OAPsys was statistically significant (Wilcoxon test; p < 0.001). VPP and OAPsys were not correlated with age, OAPdia showed a weak correlation with age on the right side (Spearman R = 0.23; p = 0.03). Blood pressure (RR) dropped from a mean 137/84 to 135/82 mmHg in the right arm and from 135/84 to 132/83 mmHg in the left arm. The change of the diastolic values of the right side and of the systolic values of the left side reached statistical significance (p < 0.05). The difference of the systolic blood pressure and the heart rate before and after CLD were weakly correlated (Spearman R = - 0.28; p = 0.01). The extent of the systemic blood pressure drop was not correlated with the maximum force affecting the globe.
  
  
  CONCLUSIONS
  The slightly lower blood pressure after CLD could be related to the oculocardiac reflex. This has to be confirmed in further trials with continuous blood pressure determination. In agreement with literature reports, significant differences between right and left eyes were found regarding OAPdia and OAPsys.
authors.affiliation: Augenklinik, Universitätsklinikum Schleswig-Holstein, Campus Kiel.
authors.forename: F
authors.initials: F
authors.lastname: Rüfer
authors.affiliation: Augenklinik, Universitätsklinikum Schleswig-Holstein, Campus Kiel.
authors.forename: B
authors.initials: B
authors.lastname: Köpke
mesh_terms: D000328:Adult; D062186:Arterial Pressure / Q000502:physiology*; D001795:Blood Pressure Determination / Q000295:instrumentation* / Q000379:methods; D003261:Contact Lenses; D004867:Equipment Design; D005260:Female; D006801:Humans; D008297:Male; D009880:Ophthalmic Artery / Q000502:physiology*; D009884:Ophthalmodynamometry / Q000295:instrumentation*; D012016:Reference Values; D012024:Reflex, Oculocardiac / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014690:Venous Pressure / Q000502:physiology*