Purpose: To examine whether whole blood prevents indocyanine green (ICG) toxicity on in vitro retinal pigment epithelium (RPE) and prevents RPE staining in ICG-assisted macular hole (MH) surgery.
Design: In vitro study and prospective case series.
Participants: In vitro study and 20 patients who underwent ICG-assisted MH surgery (20 eyes).
Methods: In the in vitro study, cultured human RPE cells were covered with balanced saline solution (BSS), heparinized whole blood, plasma, or packed red blood cells, then exposed to various concentrations of ICG. One cohort was incubated in the dark; the other cohort was exposed to light. Indocyanine green toxicity was evaluated by mitochondrial dehydrogenase assay. In the clinical study, a prospective noncomparative review of 20 consecutive patients (20 eyes) with stage 3 to stage 4 MH who underwent surgery with ICG to stain the internal limiting membrane (ILM) was performed. Indocyanine green solution (0.5 mg/ml) was used to stain the ILM after autologous whole blood covered the macular hole area. Postoperative staining of ICG on RPE was detected by an infrared-sensitive camera.
Main outcome measures: Cultured human RPE cell viability, macular hole closure rate, median visual acuity preoperatively and postoperatively, postoperative ICG staining, and retinal changes.
Results: Cultured human RPE cells covered by whole blood or plasma showed no decrease of mitochondrial dehydrogenase even in 5.0 mg/ml concentration of ICG for 20 minutes with or without light exposure. Conversely, those exposed to ICG and covered with BSS demonstrated a significant decrease of mitochondrial dehydrogenase after incubation in 5, 2.5, and 1.0 mg/ml for 20 minutes in the dark and in 5 to 0.05 mg/ml with light. Clinically, no postoperative staining on RPE was detected. No atrophic RPE changes or other retinal changes were observed in the previous MH area that was covered by autologous whole blood in all 20 eyes on average follow-up of 10.6 months. The hole closed in 19 eyes (95%) on first surgery. Visual acuity improved in 17 eyes (85%) on most recent follow-up.
Conclusions: Whole blood prevents ICG toxicity in RPE cell culture and prevents staining of RPE in surgery of MH when the ILM is stained with ICG.