Abstract
Purpose: :
To assess the correlation between retinal thickness and morphologic features evaluated from time domain optical coherence tomography (TDOCT) images with visual acuity (VA) in treatment naïve eyes with NV-AMD.
Methods: :
TDOCT scans (Stratus) with active NV AMD without treatment taken between 2006 and 2007 were evaluated. OCT quality assessment was performed to assess reliability of retinal thickness measurements. Caliper measurement of center point (CP) thickness was performed in eyes with unreliable instrument measurement. Morphological evaluation included presence, location and lateral extent of subretinal fluid (SRF), cysts, vitreo-retinal interface abnormalities, RPE lesion complex and serous pigment epithelial detachment(SPED). When present in the center of the macula, the height of SRF, RPE lesion complex and SPED were also measured.
Results: :
TDOCT scans from 337 subjects (337 eyes) were reviewed. The mean best corrected ETDRS visual acuity was 47 letters (SD 17). Instrument generated CP was reliable in 136 scans (40%), the rest were caliper measured. The mean CP retinal thickness was 319 µ (+/-173). The correlation coefficient (r) between VA and CP thickness (ILM to top of RPE or lesion complex) was -0.32 and with total retinal thickness (including RPE lesion complex) was - 0.38. The following morphologic variables were present in the central subfield; SRF 98 eyes (29%), cysts 211 eyes (63%), epiretinal membrane 22 eyes (7%), posterior vitreous detachment 110 eyes (33%), RPE lesion complex 273 eyes (88%) and SPED 52 eyes (15%). Of these variables the presence of SRF and cysts in the central subfield had a strong correlation with VA (p<0.01); presence of an RPE lesion complex had a moderate correlation (p=0.03). Amongst measurements on morphological variables, height of SRF at center of the macula had the best correlation with VA ( r -0.37) whereas RPE lesion complex had a lower correlation ( r -0.26).
Conclusions: :
The correlation between CP thickness and visual acuity is modest. Presence and severity of SRF seems to be an important morphological variable when correlating with VA in eyes with NVAMD.
Keywords: age-related macular degeneration • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • visual acuity