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Caspar Geenen, Maria Teresa Sandinha, David Steel; External limiting membrane deformation as a prognostic factor in idiopathic macular hole surgery. Invest. Ophthalmol. Vis. Sci. 2016;57(12):1098.
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© ARVO (1962-2015); The Authors (2016-present)
Although measurements such as base diameter and minimum linear diameter (MLD) have been shown to predict anatomical success, there is still a need for accurate predictors of visual outcome after pars plana vitrectomy for idiopathic macular hole. Spectral domain optical coherence tomography (SD-OCT) allows visualisation of the external limiting membrane (ELM), which is suspected to play a role in the disease process. We hypothesised that the size and/or elevation of the central opening in the ELM is a prognostic factor for visual outcome.
We performed a retrospective study of 28 patients, who underwent pars plana vitrectomy for idiopathic macular hole, performed by two surgeons at the same centre.Pre-operative high density SD-OCT scans were analysed to determine the diameter of the ELM opening (“ELM gap”), and the distance from the central edge of the ELM to the retinal pigment epithelium (“ELM elevation”). MLD and base diameter of the macular hole were also measured.Best corrected visual acuity (BCVA) three months after surgery was selected as the primary outcome. Secondary outcomes were improvement of BCVA, minimum foveal thickness, and the post-operative size of the defects in the ELM and the inner segment ellipsoid layer.Pearson correlation coefficients and their p-values were determined for each parameter against all outcomes. Multivariate regression analysis was used to confirm significant correlations.
All macular holes were closed after surgery. No single parameter was significantly correlated to post-operative BCVA.Using improvement of BCVA as the outcome, a significant correlation was found with ELM gap (p=0.049), as well as pre-operative BCVA (p=0.00005). No such correlation could be demonstrated for MLD (p=0.32), base diameter (p=0.29) or ELM elevation (p=0.87).MLD (p=0.0004), base diameter (p=0.012) and ELM gap (p=0.00002) were significantly correlated to post-operative minimum foveal thickness. These three parameters were highly intercorrelated. Multivariate analysis confirmed ELM gap to be a significant predictor of post-operative foveal thickness.
ELM gap was a significant predictor of post-operative minimum foveal thickness and improvement in BCVA. Although its correlation to post-operative BCVA was not significant, high correlations with other outcomes suggest that it is a more valuable prognostic factor than MLD and base diameter.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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