Changes in the choroidal circulation of rabbit following RPE removal.
OBJECTIVE
To examine the effects of surgical removal of the retinal pigment epithelium (RPE) on the choroidal circulation of the rabbit.


METHODS
The retina and choroid were examined by biomicroscopy, scanning laser ophthalmoscopy, fluorescein and indocyanine green angiography and histology at various times after the surgical removal of the RPE by gentle aspiration following a prior local vitrectomy and bleb detachment. Comparison was made between small and large areas of RPE removal, or only slight pressure to the retina without removal of RPE.


RESULTS
Removal of the RPE layer causes transient leakage of vascular fluid into the subretinal space for at least a week after surgery and loss of perfusion in the underlying choroidal vessels and choriocapillaris at the débridement site. This reduction in local choroidal blood flow can occur within 15 min after RPE débridement and can be transient or permanent. Histology indicates that permanent changes are due to fibroblastic infiltration that compresses the choroidal vessels. Permanent changes tend to occur after removal of relatively large areas of RPE. The removal of small areas of RPE or slight pressure on the retina causes a transient loss of local choroidal perfusion, and fibroblastic infiltration into the choroid does not occur.


CONCLUSIONS
Removal of the RPE causes changes throughout the underlying choroid. It reduces the circulation in the large choroidal vessels as well as the choriocapillaris. If large areas of RPE are removed, this choroidal non-perfusion can be permanent due to fibroblastic infiltration. Small areas of RPE removal or slight pressure on the retina lead to only transient reduction of the choroidal flow. The rapidity with which the choroidal blood flow can be reduced implies a reflex mechanism that responds to sudden RPE pressure and/or trauma. These changes are best observed with ICG angiography.
Ivert
Lena
L
Department of Ophthalmology, St. Erik's Eye Hospital, Karolinska Institute, Polhemsgatan 50, 112 82 Stockholm, Sweden. lena.ivert@sankterik.se
Kong
Jian
J
Gouras
Peter
P
D000792:Angiography; D000818:Animals; D002829:Choroid / Q000098:blood supply*; D004396:Coloring Agents; D005451:Fluorescein Angiography; D007208:Indocyanine Green; D010857:Pigment Epithelium of Eye / Q000502:physiology*; D011312:Pressure; D011817:Rabbits; D012039:Regional Blood Flow / Q000502:physiology; D012160:Retina / Q000502:physiology; D013997:Time Factors
D004396:Coloring Agents; D007208:Indocyanine Green