A new study using high-definition optical coherence tomography (HD-OCT) finds that resolution of subretinal fluid is the most important determinant of visual acuity recovery following intravitreal Lucentis therapy for neovascular age-related macular degeneration (AMD).
This study was performed to examine the effects of Lucentis therapy on the 3 major compartments of the macular area (retinal volume, subretinal fluid volume, and pigment epithelial detachment volume) in patients with choroidal neovascularization (CNV). These compartments can be visualized using HD-OCT, but not with conventional OCT. HD-OCT was performed using a prototype of the Cirrus HD-OCT. This is a frequency domain OCT system with an axial resolution of 6 um. Conventional OCT was performed using a Stratus-OCT instrument.
Patients were examined using both conventional OCT, and HD-OCT. Intravitreal Lucentis injections were administered at baseline and weeks 4 and 8.
Detailed analysis of retinal volume (RV), subretinal fluid volume (SRFV), and pigment epithelial detachment volume (PEDV), revealed that Stratus-OCT thickness measurements include a mixture of multiple components in overall retinal thickness (RT) values because RT is defined as the distance between internal limiting membrane and RPE layers. These findings suggest that changes in retinal microstructure following Lucentis therapy might be masked in conventional OCT measurements of RT.
Using measurements obtained by conventional OCT, a significant correlation between the decrease in RT and improvement in BCVA was found (P<0.005).
Data from HD-OCT analysis showed no correlation between the decrease in RV or PEDV and improvement in BCVA. The decrease in SRFV, however, correlated well with increase in BCVA (P<0.05), as well as with the characteristic time course of vision recovery. The immediate and intensive response of SRFV to anti-VEGF therapy correlates well with the rapid recovery of visual acuity following anti-VEGF therapy.
In conclusion, HD-OCT data indicate that subretinal fluid volume is the most important determinant of visual acuity recovery following anti-VEGF therapy. SRFV may be the most important parameter to consider when defining retreatment criteria for anti-VEGF treatment regimens in the future.
WHAT IT MEANS TO YOU: OCT technology is relatively new and continues to rapidly evolve. Spectral domain OCT is the latest technology that is commercially available. HD-OCT is a variant of spectral domain OCT, and is not yet commercially available. This paper demonstrates how improvements in technology can lead to greater understanding of disease processes, and that, in turn, can lead to improvements in therapy. Recognition of the key role that subretinal fluid plays in vision recovery following anti-VEGF treatment may improve our ability to individually tailor treatment protocols.Source:http://www.ncbi.nlm.hih.gov/pubmed/18675694