Background and aims his paper investigates the roles of retinal perfusion pressure and pulse pressure in progression to sight-threatening diabetic retinopathy. Retinal perfusion pressure is dependent upon the systemic blood pressure and the intra-ocular pressure. We have examined the hypothesis that the early deleterious effect of hypertension on the retinal circulation which leads to perfusion pressure damage is due to a unique relationship between the intra-ocular pressure and the systemic blood pressure. Clinically this is manifest as hypertensive retinopathy and diabetic retinopathy.
Materials and methods From a prospective database, data on all new patients with background diabetic retinopathy referred during a three year period (n=104) were analysed for progression to sight-threatening diabetic retinopathy.
Results Retinal perfusion pressure and pulse pressure were found to be the strongest predictors of progression to sight-threatening diabetic retinopathy (Chi Square linear trend statistic, relative risk ratios).
Progression to maculopathy by quartiles
For retinal perfusion pressure, the relative risk ratios increased from 1.00 in the first quartile (39.7—50.1 mmHg), to x 5.8 in the second quartile (50.2—56.1 mmHg), to x 6.4 in the third quartile (56.2—60.0 mmHg), to x 9.1 in the fourth quartile (60.1—75.3 mmHg) (p=0.012). For pulse pressure the values were x 1.00, x 4.0, x 4.5, x 6.0 respectively (p=0.021). For systolic pressure the values were x 1.00, x 3.4, x 5.5, x 5.5 respectively (p=0.026). Diastolic pressure was not significant.
Progression to proliferative retinopathy by quartiles
For retinal perfusion pressure, the relative risk ratios increased from 1.00 in the first quartile to x 2.9 in the second quartile, x 4.2 in the third quartile to x 4.1 in the fourth quartile (p=0.002). For pulse pressure the values were x 1.00, x 1.7, x 3.8, x 5.5 respectively (p=0.002). For systolic pressure the values were x 1.00, x 0.5, x 2.9, x 3.8 respectively (p=0.008). Diastolic pressure was not significant.
Conclusion Retinal perfusion pressure and the pulse pressure are important predictors of progression to sight-threatening diabetic retinopathy.
