EVects of scleral buckling and encircling procedures on human optic nerve head and retinochoroidal circulation

Aims—To study the eVects of segmental scleral buckling and encircling procedures on tissue circulation in the human optic nerve head (ONH) and choroid and retina. Methods—Using the laser speckle method, the normalised blur (NB) value, a quantitative index of tissue blood velocity, was measured every 0.125 seconds and averaged over three pulses in the optic nerve head (NBONH) and choroid and retina (NBch-ret) in 10 patients with unilateral rhegmatogenous retinal detachment (mean age 52 (SD 17)). NBONH, NBch-ret, and intraocular pressure (IOP) in both eyes, and blood pressure (BP) were measured before, and 1, 4, and 12 weeks after the scleral buckling and encircling procedure. Results—NBch-ret on the buckled side was significantly reduced after surgery and smaller than that in the unoperated contralateral eye throughout the study period (ANOVA, p<0.0001). NBch-ret on the unbuckled side, in the foveal area, NBONH, IOP, and BP showed no significant change. Conclusions—It was indicated that the segmental scleral buckling procedure with encircling elements decreased tissue blood velocity in the choroid and retina on the buckled side but caused no significant change on tissue circulation in other areas of the fundus or ONH. (Br J Ophthalmol 2000;84:31–36) Scleral buckling procedures are the treatment of choice for the majority of uncomplicated rhegmatogenous retinal detachments. Postoperative complications related to alterations in blood supply, such as anterior and posterior segment ischaemia which usually severely influence visual recovery, are rare but have been reported by several authors. It may be possible that subclinical ischaemia after retinal detachment surgery exists in many more cases than reported. Thus, the eVects of scleral buckling procedures on ocular circulation, if they exist, have important clinical implications. Studies in which the laser Doppler technique was used indicated that the pulsatile characteristics of the retinal arterial blood flow measured in the treated eyes were altered, and that arterial flow rates in the major temporal retinal arteries were, on average, 50% lower in the treated eyes than in the unoperated contralateral eyes; removal of scleral buckling elements in two patients produced increases of 73% and 44% in arterial blood flow rates. One study using colour Doppler imaging indicated that scleral buckling procedures with encircling elements decreased average blood flow velocity in the central retinal artery by 35% on the first operative day and by 50% 1 week postoperatively but did not aVect that in the ophthalmic artery, whereas another study reported that the same surgery reduced the average blood flow velocity in the ophthalmic artery by 31% 2 days after surgery. In patients with rhegmatogenous retinal detachment, the ocular pulse amplitude in the surgically treated eyes was reportedly lower by 53% compared with fellow eyes 6 months after scleral buckling. These findings suggest that scleral buckling decreases not only retinal but also choroidal and/or optic nerve head (ONH) circulation because the ophthalmic artery is the origin of the arterial branches that supply blood to the eye. To date, however, there have been no reports on the eVect of the scleral buckling procedure on tissue circulation in diVerent parts of the human fundus—that is, in the ONH, choroid in the foveal area, and choroid and retina on the buckled and unbuckled side. We recently constructed an apparatus for non-contact, two dimensional estimation of ocular fundus tissue circulation, utilising the near infrared diode laser and the laser speckle phenomenon. The normalised blur (NB) value, a quantitative index of the tissue blood velocity, is measured non-invasively in a portion of the ONH, choroid, and retina with reasonable reproducibility. Using this laser speckle method, we studied the eVects of the scleral buckling procedure with encircling elements on tissue circulation in the ONH, the choroid in the foveal area, and the choroid and retina on the buckled and unbuckled side in patients with rhegmatogenous retinal detachment before and after primary scleral buckling. Materials and methods