• Primary outcome was ETDRS visual acuity (VA: snellen equivalent) at two meters 3 months after surgery.
  
• Assignment to ICG or TB dye was performed by the Institute of Medical Biometry and Statistics of the University Luebeck per telephone immediately before surgery. Allocation to treatment arms was done with a permuted block randomization with block size 20
  

• Secondary outcome measures were successful hole closure defined only as complete closure of the inner retinal dehiscence determined by OCT,
  
• cystoid macular edema as revealed by fluorescein angiography (FLA) and
  
• postoperative scotoma shown by SLO-microperimetry.
  

In several clinical trials the positive effect of inner limiting membrane peeling (ILM) on anatomical and functional outcome in macular hole surgery has been reported. Controversies, however, exist regarding the application and possible toxicity of dyes, facilitating the surgical procedure. Since dyes were introduced for ILM peeling several authors reported on the use of indocyanine green and trypan blue (TB) for membrane peeling or ILM removal. Recent experimental and clinical reports raise concern about the safety of ICG-assisted membrane peeling. Morphological and functional damage was described in an animal model, in human donor eyes, in cultured human pigment epithelial cells and in clinical studies using ICG in macular surgery. The intraocular tolerance of TB has been demonstrated in rabbit eyes and in retinal pigment epithelium cell viability studies. Higher concentrations of TB (0.6 or 4 mg/ml) lead to toxicity on cultured RPE cells, but the application of lower clinically relevant levels did not show any significant effect. A recent retrospective comparative analysis indicates that TB may be the safer dye. They found better anatomical and functional results than with the use of ICG.

Therefore, the aim of this study was to compare the anatomical and functional outcome after dye-assisted peeling of the ILM in patients with idiopathic macular holes using ICG or TB in a prospective and randomized trial.

Inclusion Criteria:

• Patients with idiopathic macular holes stage II-IV according to the classification proposed by Gass and a visual acuity of at least 20/200 entered this study.

Exclusion Criteria:

• Patients with secondary macular holes, previous intraocular surgery, except for uneventful cataract extraction and patients with ocular disorders that might interfere with vision such as severe cataract, exudative age-related macular degeneration or diabetic retinopathy.