title: Morphologic and functional association of retinal layers beneath the epiretinal membrane with spectral-domain optical coherence tomography in eyes without photoreceptor abnormality.
abstract: OBJECTIVE
  To access the differential thickening of retinal layers in the epiretinal membrane (ERM) and to determine their correlation with visual acuity.
  
  
  METHODS
  Prospective and comparative case series of 22 patients, each of whom has one unilateral ERM eye and one normal eye. The eyes with abnormal photoreceptor layer by OCT images were excluded. Spectral-domain optical coherence tomography (SD-OCT) images were generated with Spectralis OCT (Heidelberg Engineering, Heidelberg, Germany). The thicknesses were obtained by a volume scan program using manual segmentation of the total retina, inner retina, inner nuclear layer (INL), outer plexiform layer (OPL), and outer nuclear layer (ONL) in the fovea (1.0 mm diameter) and the parafovea (3.0 mm diameter). The thickness and the proportion of each retinal layer and their relationship with visual acuity were analyzed.
  
  
  RESULTS
  All retinal layers of ERM eyes were thicker than the patients' normal eyes (P < 0.05). In the fovea, the levels of thickness difference of inner retina (240.38%) and INL (266.26%) were significantly higher than total retina (126.7%). Visual acuity was not correlated with the retinal thickness in both ERM eyes and normal eyes (P > 0.05). However, significant correlations between visual acuity difference with retinal thickness difference were found in the total retina (rho = 0.450, P = 0.046) and the inner retina (rho = 0.602, P = 0.005) of the fovea, as well as in the inner retina (rho = 0.468, P = 0.037) and the INL (rho = 0.466, P = 0.039) of the parafovea. When we convert each retinal thickness into a proportion, in the foveal area, the percentages of thickness of the inner retina and the INL of ERM eye were significantly higher than that of the normal eye (P < 0.05), whereas that of the ONL was significantly lower (P < 0.05). In the parafoveal area, the percentage of thickness of the inner retina of the ERM eye was significantly higher than that of the normal eye (P < 0.05), whereas that of ONL was significantly lower (P < 0.05).
  
  
  CONCLUSIONS
  Idiopathic ERM affects the volume of all retinal layers. Inner retina had the most variability of thickness and is strongly associated with visual acuity changes in the case of intact photoreceptor layer.
authors.affiliation: Kong Eye Hospital, 139 Sungnae-dong, Gangdong-gu, Seoul, 134-841, Korea.
authors.forename: Hee Chan
authors.initials: HC
authors.lastname: Koo
authors.forename: Won Il
authors.initials: WI
authors.lastname: Rhim
authors.forename: Eun Koo
authors.initials: EK
authors.lastname: Lee
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019773:Epiretinal Membrane / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020419:Photoreceptor Cells, Vertebrate / Q000473:pathology; D011446:Prospective Studies; D012160:Retina / Q000473:pathology*; D041623:Tomography, Optical Coherence; D014792:Visual Acuity / Q000502:physiology*
references.citation: Ophthalmology. 2006 Aug;113(8):1425-31
references.pmid: 16766031
references.citation: Retina. 2008 Mar;28(3):447-52
references.pmid: 18327137
references.citation: Ophthalmology. 2006 Nov;113(11):2054.e1-14
references.pmid: 17074565
references.citation: Ophthalmology. 2009 Sep;116(9):1788-93
references.pmid: 19643494
references.citation: Br J Ophthalmol. 1999 Dec;83(12):1329-31
references.pmid: 10574808
references.citation: Graefes Arch Clin Exp Ophthalmol. 2007 Nov;245(11):1623-31
references.pmid: 17479277
references.citation: Retina. 2010 Mar;30(3):503-8
references.pmid: 19952992
references.citation: Am J Ophthalmol. 2009 May;147(5):865-8
references.pmid: 19232558
references.citation: Br J Ophthalmol. 2009 Feb;93(2):171-5
references.pmid: 18971234
references.citation: Am J Ophthalmol. 2008 Jun;145(6):1023-1030
references.pmid: 18342830
references.citation: Ophthalmology. 2010 Apr;117(4):798-805
references.pmid: 20045567
references.citation: Retina. 2004 Feb;24(1):57-62
references.pmid: 15076945
references.citation: Am J Ophthalmol. 1999 May;127(5):559-64
references.pmid: 10334349
references.citation: Am J Ophthalmol. 2006 Sep;142(3):435-40
references.pmid: 16935588
references.citation: Am J Ophthalmol. 2000 Dec;130(6):732-9
references.pmid: 11124291
references.citation: Eur J Ophthalmol. 2008 Nov-Dec;18(6):980-8
references.pmid: 18988172
references.citation: Ophthalmology. 1996 Dec;103(12):2142-51
references.pmid: 9003350
references.citation: Invest Ophthalmol Vis Sci. 2005 Jun;46(6):2012-7
references.pmid: 15914617
references.citation: Am J Ophthalmol. 2009 Mar;147(3):473-480.e3
references.pmid: 19054492