Abstract
Purpose:
To describe the relationship between structural and functional changes in patients with tractional epiretinal membrane (ERM).
Methods:
A series of 46 patients with clinically diagnosed tractional ERM in one eye underwent Snellen visual acuity (VA) measurement, spectral domain optical coherence tomography (SD-OCT) and macular integrity assessment (MAIA) microperimetry. The normal fellow eyes (n=36) were used as controls (criteria: normal SD-OCT and VA >6/12). VA was converted to Early Treatment of Diabetic Retinopathy Study (ETDRS) equivalent letters for analysis. Calliper thickness of foveal centre (CTF), central macular thickness (CMT, average thickness within 1mm diameter from foveal centre) and presence of tractional schisis or cysts were assessed. Functional measures included central foveal sensitivity (CFS), central macular sensitivity (CMS, average sensitivity within 1mm diameter from foveal centre) and overall average macular sensitivity (AMS). Student’s t-test and Pearson’s correlation coefficients were used for data analysis.
Results:
Study eyes demonstrated reduced functional parameters in VA and MAIA, with an average reduction of -9.75 letters in VA, -3.78dB in CFS, -2.41dB in CMS and -1.88dB in AMS compared with controls (p<0.05 for all). Average CTF and CMT (490um and 483um respectively) were significantly increased compared to controls (CTF: 238um, CMT: 287um, p<0.05 for both). A weak inverse correlation between AMS and CMT was detected in study eyes (r=-0.57, p<0.05). No significant correlations were observed between any other structural or perimetric measures. In the study eyes with intraretinal cystic or schitic changes (n=14), average CMT was significantly higher than the mean CMT of non-cystic or schitic ERM eyes (535um vs 444um, p=0.03). A significant inverse relationship between AMS and CMT (r=-0.71, p=0.004) as well as a weak inverse relationship between CMS and CMT (r=-0.66, p=0.01) were observed.
Conclusions:
Retinal thickness was significantly increased in eyes with tractional ERM. This was accompanied by significant reduction in visual acuity and macular function compared to controls. There may be a significant inverse correlation between overall macular function represented by AMS) and CMT in tractional ERM eyes with cystic or schitic changes.
Keywords: 585 macula/fovea •
688 retina