Abstract
Purpose: :
To assess prognostic factors in epiretinal membrane (ERM) surgery using spectral-domain optical coherence tomography (SD-OCT) and to describe possible advantages over time-domain (TD) OCT.
Design: :
Prospective observational case series.Forty-one patients with a diagnosis of idiopathic or secondary ERM, recruited from our outpatient department, were examined with SD-OCT and TD-OCT before and after surgery. Main outcome measures were visual outcomes and pre-defined OCT patterns. Co-factors analyzed were the type of ERM, the duration and grading of subjective metamorphopsia, simultaneous cataract surgery, the type of dyes used, the duration of surgery, gender and age. A multivariate regression analysis was performed.
Results: :
Thirty-nine patients (95%) showed an improved or stable best corrected distance visual acuity (DVA) at 3 months, whereas 36 patients (88%) showed an improved or stable best corrected near visual acuity (NVA) at 3 months. Significant correlations (>0.4) were found between the course of central retinal thickness (CRT) assessed using SD-OCT and TD-OCT (p<0.02). No significant correlations (<0.3) were seen between CRT and VA (p>0.1).Baseline DVA and NVA were found to be significant prognostic values for the postoperative decrease in CRT in both OCT systems (p<0.04) as well as for the visual outcomes (p<0.007) at 3 months. In addition, the integrity of the junction between the photoreceptor inner and outer segment (IS/OS) significantly influenced the visual outcomes at 3 months (p<0.038). The baseline profile of the internal limiting membrane (ILM) significantly influenced the NVA at 3 months (p<0.009), whereas the postoperative foveal contour significantly influenced the DVA at 3 months (p<0.025). The type of ERM, the duration and grading of subjective metamorphopsia, simultaneous cataract surgery, the type of dyes used, the duration of surgery, gender or age had no significant influence on the patients` outcome (p>0.05). Compared with TD-OCT, SD-OCT allowed for a more precise differentiation between the ERM and the retinal surface and for a better evaluation of the IS/OS line.
Conclusions: :
The presence of the IS/OS line, better visualized with the SD-OCT, can be used to predict the functional outcomes after ERM surgery. Thus, besides the visual impairment, the presence of the IS/OS line should be considered as an indication for ERM surgery. Additionally, analyzing the ILM profile and the foveal contour may help to understand limited visual outcomes after surgery.
Keywords: vitreoretinal surgery • imaging/image analysis: clinical • macula/fovea