Graefe's Archive Ophthalmology

Graefe's Arch Clin Exp Ophthalmol (1985) 223:154-157

f~r Clhl~al and Expe~mental

© Springer-Verlag1985

Measurement of flow-physiologic parameters of retinal blood circulation in type 1 and 2 diabetics before and after photocoagulation B. Oswald, W. Vilser, H. Oswald, A. Jiitte*, D. Schweitzer, E. K6nigsd6rffer, A. Deufrains, and U. Dietze Department of Ophthalmology, Faculty of Medicine, Friedrich Schiller University, Jena, German Democratic Republic

Abstract. In seven diabetics of type 1 and seven of type 2, the flow physiologic magnitudes were measured in a retinal quadrant before and after photocoagulation. The segmental blood flow, the arterial flow velocity, and the diameters of artery and vein are smaller after photocoagulation than before. Investigations into the time course of the flow-physiologic parameters following photocoagulation show that the flow-physiologic values are stationary about 2 weeks after photocoagulation.

Introduction Two of the most effective, yet merely symptomatic modes of treating diabetic retinopathy are photocoagulation (PC) and laser coagulation. They have a significant effect on the conservation of visual acuity and on the improvement in ophthalmologic retinal findings, as is commonly recognized for certain initial situations (The Diabetic Retinopathy Study Research Group 1978; Koerner et al. 1976; Koerner 1978; Freyler et al. 1977). With regard to the PC mechanism of action, however, there is controversy, as the hypotheses proposed so far are not based on sufficient data (Koerner et al. 1978; Peymann et al. 1971; Colenbrander 1975), despite proven progress in histology (Leuenberg et al. 1977; Skimotori et al. 1977). Investigations into the action of PC on the flow conditions of retinal microcirculation have been presented in rare cases only (Koerner et al. 1978 ; Kohner et al. 1975; Kohner 1976; Fries 1979; Okano et al. 1974). In the following, a report is given on pilot studies of the segmental bloodflow volume (Q), the mean blood-flow velocity over the cross section of the vessel (~), the vascular diameters of the arteries (Da) , and the veins (Dv) of type 1 and 2 diabetics before and after PC. The following questions are dealth with in the context of this article: 1. How are these flow-physiologic magnitudes altered by PC? 2. Which is the temporal course displayed by the flowphysiologic magnitudes after PC?

Materials and methods In seven eyes of type-1 and seven eyes of type-2 diabetics, the above-mentioned flow-physiologic parameters were measured at one of the large branches of retinal vessels at a distance of one papillary diameter from the papillary margin, at the same site, before and after PV. The measurements were taken with the Retinophot 211, using the combined measurement unit for fluometry described by Vilser et al. (1979). Following intravenous injection of about 2.5 cc of 10% fluorescein sodium, the minimal time difference in the passage of the indicator between both measuring sites of the two-point photometer is calculated from which, via the distance of the measuring sites, the flow velocity of the blood is determined. The diameter of the vessel is measured with the aid of rocking-plate micrometry in the ophthalmoscopic image. Blood-flow volume is calculated from blood-flow velocity and vascular diameter. The effect of refraction is considered. The calculated error of this measurement amounts to _+6%. The type-I diabetics were 2zP43 years of age, and they had had a history of diabetes for 11-29 years. The type-2 diabetics were 57-68 years of age, and they had had diabetes for 1-17 years. The flow-physiologic values found in the diabetics correlated with the history of diabetes presented (Oswald et al. 1983b) and, consequently, differed from the age-related normal values (Oswald et al. 1983 a).

Dr1 = 1.37 Dr2- 0.083

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0.160 0.170 0.180 0.1go 0.200 0.210 before PC

Fig. 1. Correlation of vein diameter (Dvl) after photocoagulation (PC) with vein diameter (Dr2) before photocoagulation in type-1 diabetics

155 Table 1. Results measured in type-1 diabetics before and after photocoagulation Patient

Sex

Z.D. M B.H. M K.P. M V.G. M C.B. F V.R. F R.D. M Mean values

Eye

L L L R R L L

Standard deviation

A (years)

40 38 42 43 31 24 28 35.1

X (years)

11 29 19 14 24 13 19 18.4

7.45

6.43

Q (mm3/s)

g (mm/s)

D a (mm)

D V (mm)

Before PC

After PC

Before PC

After PC

Before PC

After PC

Before PC

After PC

0.072 0.019 0.040 0.072 0.030 0.047 0.041 0.046

0.014 0.015 0.016 0.021 0.007 0.018 0.024 0.016

3.17 1.38 3.05 4.27 2.80 3.14 3.11 2.99

1.18 1.54 1.45 2.09 0.93 2.28 2.07 1.64

0.170 0.134 0.129 0.146 0.114 0.138 0.129 0.137

0.122 0.109 0.119 0.113 0.100 0.100 0.124 0.112

0.163 0.167 0.191 0.164 0.181 0.202 0.190 0.180

0.146 0.131 0.165 0.147 0.159 0.188 0.205 0.163

0.019

0.005

0.85

0.50

0.017

0.010

0.016

0.026

A =age; X=duration of diabetes; Q=blood-flow volume; g=mean blood-flow velocity over crossection of vessel; D A=diameter of arterial vessel; D v = diameter of the venous vessel Table 2. Results measured in type-2 diabetics before and after photocoagulation Patient

Sex

A.G. F S.I. F N.E. F T.H. F S.C. F N.W. F N.W. F Mean values

Eye

L L L L L L R

Standard deviation

A (years)

57 54 61 59 68 57 57 59 4.5

Q (mm3/s)

g (mm/s)

Before PC

After PC

Before PC

After PC

Before PC

After PC

Before PC

After PC

9 14 17 17 17 1 1 10.8

0.054 0.027 0.063 0.039 0.040 0.019 0.021 0.037

0.032 0.019 0.009 0.015 0.012 0.018 0.012 0.016

7.3

0.016

0.007

3.85 2.02 3.98 3.77 3.20 1.63 1.79 2.89 1.04

3.31 2.37 0.92 1.66 1.28 2.06 1.50 1.87 0.79

0.134 0.130 0.142 0.114 0.127 0.123 0.125 0.128 0.008

0.112 0.102 0.117 0.107 0.111 0.107 0.104 0.108 0.005

0.187 0.173 0.162 0.165 0.151 0.167 0.136 0.163 0.016

0.144 0.158 0.162 0.158 0.155 0.139 0.110 0.146 0.018

X

DA (mm)

D v (mm)

(years)

The retina of these patients was coagulated by means of the Jena Xe-coagulator with an average of 30-50 PC effects (5 °) in the region of the middle periphery. The significance of the difference between the flow physiologic values before and after PC was tested by calculation of " t " (test factor) b y " pair c o m p a r i s o n . " The probability of error used was 1% and 5%, respectively. Figure 1 gives the linear regression line, its significance, the probability of error and the relevant correlation coefficient.

Results and discussion

ter was a significant correlation found between the values before and after PC, i.e., the linear regression line depicted in Fig. 1 is significant. In type-2 diabetics, the blood-flow volume ( ~ = 5%), arterial diameter ( c t = l % ) , and venous diameter ( e = 5 % ) after PC were significantly decreased, while the blood-flow velocity, which is also reduced after PC, achieved no statistical significance. After PC, the values measured were no longer significantly different from the normal values, with the exception of the venous diameter, which was significantly smaller than the normal values even after PC. As depicted in Fig. 2 in the linear regression line, the venous diameter showed a significant correlation with the history of diabetes.

Influence o f P C on the flow-physh)logic values

The measurement results for both diabetes types after PC are compiled in Tables 1 and 2. The measurements were performed during a time period of 14 days to 7 months after PC in the type-I diabetics and of 5 to 7 m o n t h after PC in the type-2 diabetics. In type-1 diabetics, blood-flow volume (~--- 1%), bloodflow velocity ( ~ = 1%), arterial diameter (c~= 1%) and venous diameter (ct= 5%) are significantly decreased by PC. Dependent on the history of diabetes, before PC six of the seven patients revealed values compared to normal whereas, on average, this group showed no significant difference from normals after PC. Only for the venous diame-

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Fig, 2. Correlation of vein diameter (DvO after photocoagulation with history of diabetes (x) in type-2 diabetics

156 Table 3. Results measured in type-1 diabetics before and after photocoagulation Patient Sex Eye Age Day after PC

Q

5

Da

(mm3/s) (mm/s) (mm)

180-

Dv

1~o~

(mm)

M

C.B.

F

K.P.

R

M

B.K.

R

M

L

L

43

31

42

38

0 2 16 44 7 mo. 0 2 5 20 41 6 too. 0 1 4 18 0 2 8 29

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0.071 0.028 0.030 0.034 0.021 0.030 0.021 0.017

4.27 1.17 2.62 3.13 2.09 2.80 1.59 1.85

0.014 0.007 0.040 0.020 0.015 0.016 0.019 0.034 0.020 0.014

1.59 0.93 3.05 1.52 1.27 1.45 1.38 2.33 1.66 1.54

0.146 0.176 0.120 0.118 0.113 0.114 0.129 0.108 0.107 0.106 0.100 0.129 0.131 0.123 0.119 0.134 0.137 0.125 0.109

0.164 0.196 0.156 0.156 0.147 0.181 0.175 0.185 0.158 0.167 0.159 0.191 0.188 0.170 0.165 0.167 0.158 0d42 0.131

-

60-

I PC

Time (days)

(year)

Fig. 4. Course of mean blood-flow velocity (5) in % of initial value after photocoagulation (PC) in four type-1 diabetics

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Fig. 5. Course of arterial diameter (DA) in % of initial value after photocoagulation (PC) in four type-1 diabetics 0.170.16 120-

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110-

= 0.002 x + 0.123 ( r= 0.87)

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100-

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a,

x (years)

Fig. 3. Course of blood-flow volume (Q) in % of initial value after photocoagulation (PC) in four type-1 diabetics

"-..... .............. .-... . . . . . . . . . . . . . . . . . .

90-

I > o

8070-

PC Time (days)

( year )

Fig. 6. Course of venous diameter (Dr) in % of initial value after

Temporal course of the photocoagulation effect Table 3 contains the measurement results obtained from four type-I diabetics at various time points after PC. These results are plotted in Figs. 3-6. Again, the t e m p o r a l courses illustrate a reduction in the flow-physiologic values. The blood-flow volume and blood-flow velocity already show m a r k e d l y reduced values I to 2 days after PC at the latest. In contrast, the arterial diameters and p a r t o f the venous diameters have distinctly increased at 1-2 days after PC as c o m p a r e d to their values before PC. This is suggestive of an i n f l a m m a t o r y reaction. A t a b o u t 15 days, the vascular diameters are certain to have reached their stationary values. This means that flow-physiologic values after PC should be measured, if possible, m o r e than 2 weeks after PC in order to circumvent the influence o f the nonstationary time period. A n exception is the curve measured in patient B.H. whose b l o o d - f l o w volume a n d blood-flow velocity first rose and then again fell to a b o u t their values before PC without significant reduction. In contrast to the other type-1 diabetics, this patient exhibited a stage-3 r e t i n o p a t h y ; in accordance with his diabetes history o f 29 years before PC, he

photocoagulation (PC) in four type-I diabetics

already had decreased blood-flow volume and blood-flow velocity c o m p a r e d to n o r m a l (Oswald et al. 1983a). M o r e over, the measurement was carried out in a q u a d r a n t in which only a few p h o t o c o a g u l a t i o n foci are localized, as c o m p a r e d to the other quadrants. The results presented provide further evidence that photocoagulation causes substantial alterations in retinal microcirculation.

References Colenbrander MC (1975) Hydrostatische Druckverh/iltnisse im Auge. Klin Monatsbl Augenheilkd 167:94-97 The Diabetic Retinopathy Study Research Group (1978) Photocoagulation treatment of proliferative diabetic retinopathy. The 2nd report of diabetic retinopathy study findings. Trans Am Acta Ophthalmol, Otolaryngol 85:82-106 Freyler H, Klemm U, Arnfelser H (1977) Hat die Photokoagulation die Prognose der diabetischen Retinopathie verbessert? Ophthalmologica (Basel) 175 : 130-139

157 Fries K (1979) Zur Interpretation der retinalen Kreislaufzeit bei der diabetischen Retinopathie vor und nach Lichtkoagulation. Dissertation, Bern Koerner F (1978) Photokoagulation der diabetischen Retinopathie, Analysen und Konzepte. 63. Tagung der Wiirttembergisehen Augen~irztl. Vereinigung 1978, Tiibingen. Klin Monatsbl Augenheilkd 173 : 138 Koerner F, Schlegel D, Koerner U (1976) Diabetic retinopathy study: preliminary results from 215 patients, treated unioculary with photocoagulation. Graefe's Arch Clin Exp Ophthalmol 200 : 99-111 Koerner F, Fries K, Niesel P, Dubied P (1978) Zur Interpretation der retinalen Kreislaufzeit bei der Retinopathie vor und nach Photocoagulation. Klin Monatsbl Augenheilkd 172: 440-444 Kohner EM (1976) The problems of retinal blood flow in diabetes. Diabetes 25 : 839-844 Kohner EM, Hamilton AM, Saunders SI, Sutcliffe BA, Bulpitt CI (1975) The retinal blood flow in diabetes. Diabetologica 11:27-33 Okano T, Hornicki T, Sarmja S (1974) Effects of photocoagulation on the velocity of retinal circulation in diabetic retinopathy. Acta Soc Ophthalmol Jpn 9: 926-938

Oswald B, Vilser W, Oswald H, Jiitte A, K6nigsd6rffer E, Schweitzer D (1983 a) Messung von h~imodynamischen Gr6Ben der Netzhautdurchblutung. Graefe's Arch Clin Exp Ophthalmol 220:39-41 Oswald B, Vilser W, Oswald H, Jfitte A, K6nigsd6rffer E, Schweitzer D (1983 b) Messung von h/imodynamischen Gr6gen der Netzhautzirkulation bei Diabetikern Typ I und 2. Graefe's Arch Clin Exp Ophthalmol 220:42-46 Peymann GA, Spitznas M, Straatsma BR (1971) Peroxidase diffusion in the normal and photocoagulated retina. Invest Ophthalmol 10:181 Skimotori M, Oktsuka Y, Suguro K, Takeda N (1977) Riboflavin angiographic fundus of photocoagulated eyes in Rabbits. Acta Soc Ophthalmol Jpn 81:595-600 Vilser W, Brandt HP, K6nigsd6rffer E, Wittwer B, Jiitte A, Dietze U (1979) Messung zur Ermittlung des Blutvolumendurchflusses in grol3en retinalen Gef/igen des Menschen. Graefe's Arch Clin Exp Ophthalmol 212:41

Accepted November 20, 1984