New developments in OCT evaluations

Abstract

Diabetic macular edema (DME) is one of the most common causes for visual loss (Ciulla et al., Diabetes Care, 2003). DME is characterized by an abnormal increase of the retinal thickness (RT) due to the accumulation of liquids in the retinal tissue, consequence of the first response to the inflammatory process occurring in diabetic retinopathy (DR). It is therefore considered one of the most important indicators of DR progression. Other indicators, such as microaneurysms and retinal leakage, were also observed and quantified in a prospective longitudinal 3-year follow-up study involving type 2 diabetic patients with nonproliferative DR. Patterns of progression were established based on these ophthalmic indicators (Lobo et al., Arch Opthalmol., 2004). OCT plays an important role in the assessment and quantification of DME. Stratus OCT version established a 9 area map for RT, being the central area of 1000µm in diameter. However, there is a lack of detailed information when studying DME. This problem was addressed by the use of an atlas of the human macula in a recent work from our group, where the merging of radial and circular scans was made possible (Bernardes et al., IOVS, 2008). Recently, Carl Zeiss introduced Cirrus HD-OCT, a Fourier domain OCT, allowing to achieve more detailed information of the macular area, performing either 512×128 or 200×200 B-scans, and allowing to export an eye fundus image for reference. It is now possible to assess local RT and correlate it with any imaging modalities available.