[Treatment of central retinal vein occlusion by isovolemic hemodilution]

Red Blood Cells: A Newly Described Partner in Central Retinal Vein Occlusion Pathophysiology?

Central retinal vein occlusion (CRVO) is a frequent retinal disorder inducing blindness due to the occlusion of the central vein of the retina. The primary cause of the occlusion remains to be identified leading to the lack of treatment. To date, current treatments mainly target the complications of the disease and do not target the primary dysfunctions. CRVO pathophysiology seems to be a multifactorial disorder; several studies did attempt to decipher the cellular and molecular mechanisms underlying the vessel obstruction, but no consensual mechanism has been found. The aim of the current review is to give an overview of CRVO pathophysiology and more precisely the role of the erythroid lineage. The review presents emerging data on red blood cell (RBC) functions besides their role as an oxygen transporter and how disturbance of RBC function could impact the whole vascular system. We also aim to gather new evidence of RBC involvement in CRVO occurrence.

Hemodilution therapy using automated erythrocytapheresis in central retinal vein occlusion: results of a multicenter randomized controlled study

BACKGROUND

Central retinal vein occlusion (CRVO) leads to poor visual outcome in most eyes. Abnormal hemorheology was suspected to play a major role in its pathogenesis. CRVO treatment is still a matter of debate but several studies have pointed out the efficacy of isovolumic hemodilution. The aim of this study was to assess the feasibility and efficacy of hemodilution using automated erythrocytapheresis in recent-onset CRVO.

METHODS

In this prospective randomized controlled multicenter study, 61 consecutive CRVO patients were enrolled when they met the following criteria: CRVO lasting for 3 weeks or less, visual acuity ranging from 20/200 to 20/32, age between 18 and 85 years, no diabetes, no uncontrolled systemic hypertension, no antiplatelet or anticoagulant therapy, hematocrit higher than 38%, and signed informed consent. Patients were randomly assigned to the hemodilution group (n = 31) or to the control group (n = 30). Hemodilution therapy consisted of one session of erythrocytapheresis on outpatient basis, followed by additional session(s) for 6 weeks if needed. Target hematocrit was 35%. Follow-up was 12 months.

RESULTS

No statistical differences in age, associated risk factors, or CRVO characteristics were observed at baseline between both groups. Mean visual acuity was equivalent to 20/80 in the hemodilution group and to 20/63 in the control group (non-significant difference). In the treated group, mean number of hemodilution sessions was 3.3 (range, 1 to 6), and no major side-effects occurred. At the 12-month follow-up visit, 64.5% of the hemodilution group had visual acuity of 20/40 or better compared to 40% of the control group (p = .048). Visual change was a gain of 1.7 ETDRS line in the hemodilution group versus a loss of 2.3 lines in the control group (p = .007). There was less conversion into an ischemic form in the hemodilution group (11%) than in the control group (50%, p = .004). Mean final retinal thickness was 289 μm in the hemodilution group versus 401 μm in the control group (p = .068).

CONCLUSIONS

This multicenter controlled randomized study demonstrated that automated erythrocytapheresis is a safe and effective tool for performing hemodilution and confirmed that hemodilution therapy can improve the final prognosis of CRVO when applied in the early phase of the disease.

[Isovolumic hemodilution in the management of the acute phase of central retinal vein occlusion: a pilot study]

INTRODUCTION

Cases series and randomized studies support the use of isovolumic hemodilution at the acute phase of the central retinal vein occlusion (CRVO). However, a recent meta-analysis showed the difficulty of interpreting the long-term effect of isovolumic hemodilution because of the late complications and the concomitant use of other treatments. We present here a pilot case-series study aiming to demonstrate the effect of isovolumic hemodilution at the acute phase of the disease, before any other treatment was applied.

PATIENTS AND METHOD

Twenty-two consecutive cases of CRVO were prospectively treated with isovolumic hemodilution within 15 days of disease onset (substitution of 10 ml/kg of blood by a macromolecular solution (Voluven), aiming at a hematocrit of 35%). The treatment was performed in ambulatory conditions after excluding common contraindications (cardiac, respiratory and renal insufficiency, angina pectoris, history of heart attack or stroke during the last 6 months). The patients were followed prospectively with respect to visual acuity, fluorescein angiography and visual acuity at one week, one month, three months and twelve months.

RESULTS

Visual acuity improved of at least one ETDRS line (5 letters) in 59% of the patients one week after the treatment. Improvement in the haemodynamic was observed in all these cases on fluorescein angiography. The vision remained stable at 1 month and 3 months before any other treatment was applied. After the 3rd month, additional intravitreous injection of triamcinolone was applied in 32% of eyes for persistent macular edema. At 12 months after hemodilution, visual acuity improved in 64% of cases and only 5% of the eyes converted into an ischemic CRVO.

DISCUSSION

Isovolumic hemodilution at the acute phase of the CRVO is followed by an improvement in both vision and angiographic characteristics in more than 60% of our patients and the conversion into an ischemic form was limited to 5% of eyes. Further randomized studies are needed to evaluate the specific effect of hemodilution in the long term.