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Reporrs No. 9 1919 Investigative Ophthalmology & Visual Science. V o l . 3 1 , No. 9. September 1990 Copyright © Association for Research in Vision and Ophthalmology Blood Velocity in the Ophthalmic Artery in Normal Subjects and Patients with Endophthalmitis Georg Michelson,* Kornelio Gierrh,* Rolf Priem,-|- and Rudolf Laumerf Some ocular diseases lead to temporary changes in the ocular blood circulation. This study was undertaken to evaluate changes in the blood-flow velocity of the ophthalmic artery in patients with endophthalmitis. With pulsed Dopplcr sonography the blood velocity of the ophthalmic artery was measured in 50 normal subjects and in ten patients with bacterial endophthalmitis. In normal subjects blood velocity decreased with increasing age, and the average systolic/ diastolic blood velocity in cm/sec were 38.8 ± 6.3/11.6 ± 4.7 in the 18-50-ycar-old age group and 28.3 ± 4.6/6.7 ± 3 . 3 in the 51-88-ycar-old age group. Endophthalmitis produced increased systolic/diastolic blood velocity in the ophthalmic artery in the affected eyes in cm/sec (99.7 ± 15.5/26.6 ± 10.5 in the 16-50-year-old age group; 60.4 ±8.8/16.6 ± 4 . 8 in the 51-83-year-old age group). Some patients showed similar changes in the unaffected fellow eyes. The noted elevation of the blood velocity in unaffected eyes may be due to the bilaterally projected parasympathetic fibers of the oculomotor nerve. Invest Ophthalmol Vis Sci 31:1919-1923, 1990 Many ocular diseases are associated with altered blood flow in the ophthalmic artery. We know less about temporary changes of ocular circulation in states of severe ocular inflammation. Endophthalmitis may produce ocular hyperemia with increased blood flow to the affected eye. We determined if patients with endophthalmitis develop an increased blood velocity in the ophthalmic artery detectable by pulsed ultrasound Doppler sonography.1"8 Materials and Methods. The Doppler principle describes the frequency shift of received wave energy caused by a moving reflector (in our case, moving blood). The frequency shift f depends on the velocity v of the red cells and on the angle a between the vessel and the insonation beam: f = 2 f0 v cosine a/c; where fo = 2 MHz and c = 1540 m/sec (c = propagation velocity of ultrasound through tissues). By rearranging the equation, the velocity component, v*, which causes the frequency shift, f, can be calculated: v* = 39 f. The measured blood velocity, v*. is related to the real blood velocity, v, by the cosine of the angle, a, between the axis of the ultrasound beam and the vessel. Due to this function the trigonometric velocity error (TVE) depends on the angle a: TVE(%) = (1 - cosine a) 100 with TVE(%) = (v - v*) 100/v Downloaded From: http://iovs.arvojournals.org/ on 05/05/2017 and v* = v cosine a. Within an insonation angle a of 40° (-20°-+20°), the TVE is therefore maximally 8%. All further data are based on the measured velocity, v*. Pulsed Doppler sonography measures blood velocity of orbital vessels at given spatial intervals from a reference point (temporal upper lid), with a sample length of 4 mm, parallel to the ultrasound beam. With the direction of insonation from the upper lid to the optic foramen and an orbital measuring depth of 39 ± 4 mm the identification of the ophthalmic artery just after entering the orbit was achieved (Figs. 1, 2). After visual and acoustic optimization of the pulse curve (monitor and headphones) by varying the angle a with the hand-held transducer, 12 pulse curves of each eye were stored. The arithmetic means of the systolic (vsys), diastolic (vdia), and mean velocity are used in further data. With a pulsed ultrasound Doppler sonograph (4 MHz; EME, Uberlingen, West Germany), the ophthalmic arteries of 50 normal subjects (average age. 38.7 ± 18; range, 18-80 yr) and often patients (range, 16-83 yr) with bacterial endophthalmitis were examined. Bacterial endophthalmitis was caused by perforating injury in four patients and by complicated cataract extraction in six patients. We compared the v sys, vdia, and vascular resistance—Pourcelot index [PI] = (vsys - vdia)/vsys—in the ophthalmic arteries of the two groups. Informed consent was obtained from all patients and subjects before of the investigation. Results. In normal subjects both the vsys and vdia in the ophthalmic artery decreased significantly with increasing age (vsys: linear correlation coefficient r = -0.56, P < 0.001; vdia: r = 0.52, P < 0.0001). Average vs>s/vdia in cm/sec were 38.8 ± 6.3/11.6 ± 4.7 in the 18-50-yr-old age group and 28.3 ± 4.6/6.7 ± 3.3 in the 51-80-yr-old age group (Figs. 3. 4). Vascular resistance of normal subjects also increased with increasing age (linear correlation coefficient r = 0.275; P < 0.05) (Fig. 5). All ten patients with endophthalmitis showed significantly increased blood velocity in the affected eye up to an average of 99.7 ± 14.5 cm/sec in the 16-50yr-old age group (P = 0.0001, Mann-Whitney-Wilcoxon test) and 60.4 ± 8.8 cm/sec in the 51-83-yr-old 1920 INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE / Seprember 1990 Vol. 31 Pulsed Doppler Sonograph Fig. 1. Schematic picture of the pulsed 4 MHz transducer examining the ophthalmic artery. Ophthalmic Artery Sample Volume Ophthalmic Fig. 2. Normal pulse curve of the ophthalmic artery measured by a pulsed ultrasound Doppler sonograph (4 MHz) in 39 mm orbital depth from the temporal upper lid. Downloaded From: http://iovs.arvojournals.org/ on 05/05/2017 Fig. 3. Systolic blood velocities in the ophthalmic artery of 50 normal subjects (right eyes, OD; left eyes, OS) and in 10 patients with cndophthalmitis (affected eyes, unaffected fellow eyes) with increasing age. Note the linear regression line of normal right eyes (linear correlation coefficient r = -0.56. /J = 0.001) with 2 standard deviation (SD) range. Seven of ten patients with cndophthalmitis showed also increased velocities in the unaffected fellow eyes outside of the ±2 SD range. 1921 Reporrs No. 9 * Affected eye SYSTOLIC BLOOD UELOCITY IN ENDOPHTHALMITIS 12B ° Unaffecte d fellow eye IBB * Normal eye OD .E 88 - Norma1 eye OS 14B U CD E u >- 68 + (J o "o _ _• o c 2SD 48 _J" u > 28 --—2SD 8 -H 18 28 38 48 58 1 68 \— 78 1 1 88 98 — L inear Regress io n Line OD - +- 2 SD Range AGE in years age group (P = 0.0001, Mann-Whitney-Wilcoxon test) during systole in comparison with normal subjects. In seven often patients elevated vsys outside the range of two standard deviations was noted also in the unaffected fellow eye (Fig. 3). Eight often patients had significantly increased vdia blood velocities in the affected eye (18-50-yr-old age group: vdia 26.6 ± 10.5, control 11.6 ± 4.7 cm/sec, P < 0.001 Mann-Whitney-Wilcoxon test; 51-83-yr-old age group: vdia 16.6 ± 4.8, control 6.7 ± 3.3 cm/sec, P < 0.001 Mann-Whitney-Wilcoxon test) (Fig. 4). The PI of the affected eyes and of the unaffected fellow 60 Fig. 4. Diastolic blood velocities in the ophthalmic artery of 50 normal subjects (right eyes OD, left eyes OS) and in 10 patients with cndophthalmitis (affected eyes, unaffected fellow eyes) with increasing age. Note linear regression line of normal right eyes (linear correlation r = -0.52. P< 0.001) with ±2 SD range. eyes did not differ significantly from normal subjects (Fig. 5). Systemic features like blood pressure, erythrocyte sedimentation rate, and leukocyte count were normal. In patient LA, 69 yr of age, the blood velocities were observed for 60 days after complicated extracapsular cataract extraction/intraocular lens implantation with postoperative endophthalmitis. In this patient the blood velocity normalized after 60 days in both eyes (Fig. 6). Discussion. We observed three phenomena: (1) in normal subjects we found a decrease of vsys and vdia in * Affected eye DIASTOLIC BLOOD UELOCITY IN ENDOPHTHALMITIS T ° Unaffected fe1 low eye O 50QJ E ' Normal eye OD 40 o - Normal eye OS 30 o 20 — L inear regress ion 1 ine normal eye OD . 10 - +- 2 SD Range 18 28 30 40 50 60 AGE in years Downloaded From: http://iovs.arvojournals.org/ on 05/05/2017 70 88 98 1922 INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE / Seprember 1990 l X LJ Q Z * Affected eye POURCELOT-INDEX P . I . IN ENDOPHTHALMITIS P.I. =(Usys-UdiaVUsys 1,1- o Unaffected fe1 low eye - • 8,9 - Norma1 eye OD +2SD 8,8 • " Normal eye OS 8,7 Ld O o — Linear Regress ion Line Norma1 eye OD 8,6 -2SD 8,5 Vol. 31 8,4- — + - 2 SD Range Fig. 5. Pourcclot Index (index for vascular resistance, P.I. = (Vsys - Vdias)/Vsys) of 50 normal subjects and of 10 patients with endophthalmitis (affected eye, unaffected fellow eye) with increasing age. Note linear regression line (r = 0.275, P < 0.05) with ±2 SD range of normal right eyes. Both the affected eyes and the unaffected fellow eyes showed values inside the ±2 SD range. 8,3 18 28 38 48 58 68 78 88 98 AGE in years the ophthalmic artery and an increase of the vascular resistance with increasing age; (2) in patients with endophthalmitis we measured increased blood velocities in the affected eyes; and (3) in some patients there were also increases in the unaffected fellow eyes. The cause of these observations is unknown. The age-related decrease of the blood velocity and the increased vascular resistance in the ophthalmic artery may depend on diminished perfusion pressure caused by age-related arteriosclerosis. The phenomenon of age-related decrease of the blood velocity is already known in cerebral arteries.9"13 The significant elevation of the blood velocity in the ophthalmic artery in affected eyes may be due to a secondary hyperemia in the choroid and/or to a secondary vasospasm of the ophthalmic artery. The release of prostaglandins in affected eyes may stimulate trigeminal sensory nerves, producing choroidal vasodilation through parasympathetic fibers of the oculomotor nerve.14"16 The associated blood velocity elevation in the unaffected fellow eyes may contribute to bilaterally projected sympathetic fibers with vasospasm of the ophthalmic artery in the unaffected fellow eyes. The normal vascular resistance in eyes with Time course Patient L.A., 69 years •"•• a f f e c t e d eye °- unaffecte d fel low eye - normal range 69 years - + 2 SD - days Downloaded From: http://iovs.arvojournals.org/ on 05/05/2017 - 2 SD Fig. 6. Time course of the systolic blood velocity after complicated ECCE/IOL with endophthalmitis (L.A., 69 years) in comparison to normal systolic blood velocity with ±2 SD range. Reporrs No. 9 endophthalmitis can be an argument for the hypothesis that the increase in blood velocity is due partially to a vasospasm of the ophthalmic artery. Key words: pulsed Doppler sonography, blood velocity, ophthalmic artery, normal subjects, endophthalmitis From the Departments of "Ophthalmology and fNcurosurgery, University Erlangen, Niirnberg, West Germany. Reprint requests: Gcorg Michclson, Augenklinik mit Poliklinik, Universitat Erlangcn-Nurnbcrg, Schwabachanlagc 6, D-8520 Erlangen, West Germany. References 1. Canning CR and Restori M: Doppler ultrasound studies of the ophthalmic artery. Eye 2:92, 1988. 2. Cellini M, Profazio V, Barbaresi E, and Scarpellini I: Doppler measuring in induced ocular hypertony. Ann Ottalmol Clin Ocul 111,6:491, 1985. 3. Evans DH, Barric WW, Asher MJ, et al: The relationship between ultrasonic pulsatility index and proximal arterial stenosis in canine model. Circ Res 46:470, 1980. 4. Fcdorov SN, Ivashina AI, Mikhaylova GD, and Niketin YM: Possibilities for investigation of hemodynamics of the eye with the help of ultrasonic apparatus Dopscan. Oftalmol Zh 3:169, 1986. 5. Nilsson SFE, Lindner J. and Bill A: Characteristics of uveal vasodilatation produced by facial nerve stimulation in monkeys, cats and rabbits. Exp Eye Res 40:841, 1985. 6. Rein A, Sigal R, and Hamard H: Ophthalmic a: v r y and pulsed doppler. J FrOphtalmol 8, 4:341, 1985. 1923 7. Rittgers SE, Thornhill BM, and Barnes RW: Quantitative analysis of carotid artery Doppler spectral waveforms: Diagnostic value of parameters. Ultrasound Med Biol 9:255, 1983. 8. The Doppler standards and nomenclature committee of the American Society of Echocardiography 1986, Recommendations for terminology and display for Doppler echocardiography. In Basic Doppler Echography, Kisslo J, Adams D, Mark DB, editors. New York, Churchill Livingstone,. 9. Woodcock JP, Gosling RG, and Fitzgerald DE: A new noninvasivc technique for assessment of superficial femoral artery obstruction. Br J Surg 59:226, 1972. 10. Meyer CHA, Lowe D, Meyer M, Richardson PL, and NeilDwyer G: Progressive change in cerebral blood flow during the first three weeks after subarachnoid hemorrhage. Neurosurgery 12:58, 1983. 11. Naratomi H, Meyer JS, Yamaguchi F, and Shaw T: Effects of advancing age on regional cerebral blood flow. Arch Ncurol 36:410, 1979. 12. Aim A, Stjcrnschantz J, and Bill A: Effects on oculomotor nerve stimulation on ocular blood flow in rabbits after sympathetic denervation. Exp Eye Res 23:609, 1976. 13. Bill A: Circulation in the eye. In Handbook of Physiology. The Cardiovascular System, Vol IV. The American Physiological Society, 1984, pp. 1001-1034. 14. Bill A, Lindner M, and Lindner J: The protective role of ocular sympathetic vasomotor nerves in acute arterial hypertension. Bibl Anat 16:30, 1977. 15. Mandahl A: Release of Substance P and its Role in the Acute Inflammatory Response in the Rabbit Eye. Thesis. Acta Univ. Upsaliensis, 1983, pp. 1-29. 16. Nilsson SFE and Bill A: Vasoactive intestinal polypcptidc (VIP): Effects in the eye and on regional blood flow. Acta PhysiolScand 121:385, 1984. Investigative Ophthalmology & Visual Science, Vol. 31. No. 9, September 1990 Copyright © Association Tor Research in Vision and Ophthalmology Human Presaccadic Spike Potentials Of Cenrrol or Peripheral Origin? Avinoom Nariv,* Joel M. Weinsrein.j- and Rodolfo Rosas-Ramos* Electroencephalographic (EEG) activity associated with voluntary and spontaneous saccades were analyzed in 12 normal subjects to determine the influence of volition upon the presaccadic spike potentials (SPs). In addition, two different electrode configurations, of a temporal and a parietal derivation, and two different filter bandwidths were simultaneously analyzed to clarify issues regarding the structure, function, and origin of SPs. An off-line averaging of the preand postsaccadic EEG epochs showed distinct spike potentials associated with spontaneous saccades in both the temporal and the parietal locations. Subsequent statistical analyses indicated that the amplitude of the SPs associated with spontaneous saccades was not significantly different from the respective amplitude of SPs preceding voluntary saccades. Independent effects of filter bandwidth and electrode Downloaded From: http://iovs.arvojournals.org/ on 05/05/2017 derivation are suggestive of a complex late presaccadic EEG activity. Invest Ophthalmol Vis Sci 31:1923-1928, 1990 Earlier work in our laboratory1 suggested that spike potentials (SPs, "cortical potentials" preceding eye movements by 10-15 msec) were associated with voluntary, but not with spontaneous, eye movements. Although scalp-recorded SPs initially suggested a posterior parietal origin for this potential,12 later work3 with dipole mapping, showed that the origin of SPs was in the orbital region, most probably derived from extraocular muscle activity. A different suggestion