Transient Visual Loss and Decreased Ocular Blood Flow Velocities Following a Scleral Buckling Procedure FREE

Scleral buckling procedures with encircling elements have been shown to decrease blood flow velocities in the central retinal artery but, in most cases, leave the ophthalmic artery unaffected.¹ Although these hemodynamic changes are well documented with otherwise successful scleral buckling procedures, they are rarely symptomatic. We report the case of a young woman who developed episodes of posturally related transient visual loss following a scleral buckling procedure with an encircling element.

A 26-year-old woman had undergone surgical repair of a 12-mm full-thickness corneoscleral laceration in the left eye 6 months previously. The laceration extended from the superior limbus to the inferior limbus. Two months after the ruptured globe repair, she developed an inferior macula-on retinal detachment, which was treated with pars plana vitrectomy and scleral buckling with a 42-style silicone encircling element (Labtician, Oakville, Ontario). The intraocular pressure was normal until 4 weeks after the surgery, when it was measured at 44 mm Hg by the Tonopen tonometer (Mentor O&O, Norwell, Mass). Treatment with topical 0.5% levobunolol and 0.2% bromonidine and oral neptazane was initiated. The intraocular pressure stabilized in the low 20s and visual acuity remained counting fingers OS at 0.3 m due to a central corneal scar.

Approximately 3 months after the retinal detachment repair, the patient complained of a several-day history of episodic transient visual loss (to the level of bare light perception) in her left eye that occurred when she stood from a seated or supine position. She had recently resumed normal daily physical activities after being restricted in the postoperative period. The episodes were reproducible and she experienced up to 10 of these episodes daily, with each episode lasting 2 to 3 minutes.

Examination at that time revealed visual acuities of 20/20 OD and finger counting at 0.3 m OS. Goldmann applanation tonometry revealed an intraocular pressure of 23 mm Hg OS that was confirmed by the Tonopen tonometer. The anterior segment examination revealed a central corneal scar with a deep and quiet anterior chamber. The retina was completely attached with a normal-appearing posterior pole. A moderately high 360° scleral buckle indentation effect was evident peripherally. Her blood pressure was 110/70 mm Hg in the right and left arms without orthostatic changes.

Color Doppler imaging was performed on the right and left eyes and revealed ophthalmic artery systolic blood flow velocities of 45 cm/s OD and 10 cm/s OS (normal mean ± SD: 31.3 ± 4.2 cm/s). The central retinal artery blood flow velocities were 11.0 cm/s OD and less than 2 cm/s OS (normal mean ± SD: 10.1 ± 1.9 cm/s). During the next week, the episodes of transient visual loss increased in frequency and duration and the patient elected to undergo excision of the encircling element.

The episodes of transient visual loss abated immediately following excision of the encircling element. Color Doppler imaging was performed 2 weeks later, and demonstrated ophthalmic artery systolic blood flow velocities of 46 cm/s OD and 38 cm/s OS and central retinal artery blood flow velocities of 15.26 cm/s OD and 11.89 cm/s OS. The intraocular pressure in the left eye at the time of the postoperative color Doppler study was unchanged at 22 mm Hg. The blood pressure and heart rate were approximately the same.

To our knowledge, this is the first reported case of a patient who experienced episodes of transient visual loss associated with documented orbital hemodynamic changes after scleral buckling with an encircling element. Presumably, central retinal artery blood flow, and possibly ophthalmic artery blood flow, was significantly reduced as a result of the encircling procedure and orthostatic decreases in blood pressure caused a further decrease in ocular perfusion. The episodes of transient visual loss resulted from the decreased ocular perfusion. Removal of the encircling band resulted in a resolution of the transient visual loss episodes and a corresponding normalization of the central retinal artery and other retrobulbar artery hemodynamic parameters as measured with color Doppler imaging.

Decreased retinal artery blood flow rate and velocity is a recognized effect of scleral buckling procedures with encircling elements. On average, a 50% decrease in blood flow velocities with an accompanied increase in resistance has been demonstrated in the major temporal arteries and in the central retinal artery following scleral buckling and encircling procedures, as measured by laser Doppler techniques and color Doppler imaging.^1- 4 Findings on fluorescein angiography also indicate that retinal and choroidal circulation is diminished by scleral buckling procedures and encircling elements.⁵ Despite the marked hemodynamic alterations, most patients seem clinically unaffected and do not experience symptoms suggestive of poor ocular perfusion.¹ However, one previously published report described a patient who developed slowly progressive visual field constriction that reversed after the encircling band was removed.² Other studies have also demonstrated the reversibility of the hemodynamic changes after removal of the encircling element or scleral buckle.^2,4

Although the decrease in retinal artery blood flow following scleral buckling procedures with an encircling element is well documented, the mechanism by which this occurs is unknown. Diddie and Ernest⁶ performed scleral buckling procedures on rabbits and found that encircling bands significantly reduced blood flow to the retina and choroid as measured by strontium 85–labeled microspheres.⁶ This effect was not seen in those eyes with segmental buckles or sham surgery. The authors speculated that the reduction of retinal and choroidal blood flow involved obstruction of choroidal venous drainage. Effects on the retinal circulation may be the result of direct or indirect increases in peripheral retinal vascular resistance from the buckle indentation.¹

In this case, a severe degree of blood flow velocity reduction was seen in the central retinal artery. In addition, the ophthalmic artery blood flow velocity was also reduced, a finding not encountered in the series of asymptomatic patients reported by Regillo et al.¹ It is likely that the retinal, and possibly choroidal, perfusion was compromised to a much greater degree than what usually occurs following routine scleral buckle procedures with encircling elements. The markedly diminished ocular perfusion produced symptoms of transient visual loss precipitated by common postural changes in a young, healthy adult. Fortunately, the hemodynamic changes and symptoms were reversible, even months after the procedure.

Supported in part by the Vitreoretinal Research and Education Foundation, Philadelphia, Pa.

Corresponding author: Carl D. Regillo, MD, Retina Service, Wills Eye Hospital, 900 Walnut St, Philadelphia, PA 19107.