Subfoveal neovascular membranes — membrane morphology and outcome after combined subretinal surgery and autologous RPE transplantation

Abstract

Purpose: We have recently described combined subretinal surgery and simultaneous autologous transplantation of RPE as a therapeutic option for the treatment of CNV in patients with advanced AMD. The purpose of the present study was to determine whether the size and morphology of the membranes were correlated with patient outcome.

Methods: We examined 19 AMD patients, which underwent combined subretinal surgery and autologous transplantation of RPE. All patients had improved or stabilized visual acuity in follow-up after surgery. The membranes were prepared for conventional histology and evaluated for their morphological composition on serial sections applying a semiquantitative score of 0, 1+, 2+ and 3+ to the following parameters: amount of acellular matrix, neovascularization/microvascular density (MVD), cellularity with special reference to inflammatory cells, and presence of RPE. These data including membrane size as determined preoperatively by fluorescein angiography (FLA) were correlated with postoperative visual acuity.

Results: By preoperative FLA all lesions were classified as clinically predominantly occult. Regarding postoperative outcome we divided all patients in two groups. Group I with visual improvement of 2 and more lines comprised 7 patients, and group Il with unchanged/stabilized visual acuity of +/−1 line the remaining 12 patients. Mean membrane size was 6,19 +/− 1,33 mm in the group of patients with, and 6,41 +/− 1,87 in the group without visual improvement, respectively. Recurrences did not occur.

Histology: All 19 membranes contained a significant amount of acellular matrix (scores 2+/3+); a prominent neovascularization/high MVD was present in 13/19 specimens and was usually associated with a high degree of cellularity, i.e. a moderate or marked inflammatory component predominated by lymphocytes (14/19). 6/19 membranes presented as minimally vascularized and acellular scars. In 15/19 cases a significant amount of RPE cells was present in the excised membranes; this prevalence was especially high in the group II.

Outcome: When compared to the development of visual acuity after therapy, neither FLA findings, nor histopathologic features of the membranes were predictive.

Conclusion: In a pilot study of 19 patients with advanced AMD/CNV treated with combined subretinal surgery and autologous RPE transplantation features other than membrane morphology and membrane size seem to determine patient outcome. The tendency for a higher amount of RPE cells in the group with no improvement should be further investigated.