Make the Best Treatment Decisions for Diabetic Macular Edema

Learn how Cirrus HD-OCT helped determine if vitrectomy was necessary in this DME case.

By Paul E. Tornambe, MD

One of the most frustrating cases the retina surgeon faces is the patient with diabetic macular edema (DME). Anti-VEGF agents aren't very effective in treating DME and could reduce vision further if macular ischemia is present. Periocular and intravitreal corticosteroids are short-acting, and subsequent injections usually are less effective and even shorter-acting. Grid laser photocoagulation, sometimes used in combination with VEGF inhibitors and steroids, may be somewhat effective, but it's associated with scotomas, areas of RPE atrophy that progressively enlarge, and sometimes iatrogenic choroidal neovascular membrane formation. Often, vitrectomy is considered if significant traction exists and after you've tried the other therapies mentioned above.

We used Stratus OCT in the past to verify retinal traction. In my experience, Cirrus HD-OCT provides unique, crisp images of the vitreoretinal interface and demonstrates the magnitude of these vitreoretinal interface forces in much greater detail. Stratus OCT revolutionized the way we examined the retina. Metaphorically speaking, Stratus OCT took us from radio to black and white TV. Cirrus HD-OCT takes us from black and white TV to high-definition (millions of colors) TV, providing much more detail and information that we can use in daily practice. The following case demonstrates the clinical relevance of Cirrus HD-OCT.

A Case of DME

A 64-year-old woman with insulin-dependent diabetes presented with DME. Over the last 2 years, her right eye was treated with laser photocoagulation, periocular steroids and, more recently, with 6 monthly injections of ranibizumab (Lucentis, Genentech, South San Francisco, Calif.). The macular edema showed little improvement, and her visual acuity remained in the 20/50 to 20/60 range.

Crystal Clear Images

The patient's vision in the fellow eye declined from 20/20 to 20/60. The high-resolution B-scans of Cirrus HD-OCT showed macular edema in both eyes. The B-scans revealed some traction near the posterior hyaloid (PH), which was greater in the left eye than in the right eye (Figure 1). The topography map demonstrated the extent of the macular edema in each eye (Figure 2).

Figure 1. These high-resolution, horizontal raster B-scans from Cirrus HD-OCT show traction by the posterior hyaloid (PH) OU. Traction is more extensive in the left macula (right) than in the right macula (left).

Figure 2. This topography map image demonstrates significant macular edema in the patient's left eye.

The topography map superimposed on the retinal image located the edema in relation to retinal vessel landmarks, which may help determine where to apply focal laser photocoagulation (Figure 3). However, only the 3D cube scans of Cirrus HD-OCT, vividly shows the extent of the vitreous traction on the retina in each eye (Figure 4). The B-scan and topography images don't demonstrate the magnitude of vitreous traction, especially in the right macula.

Figure 3. The topography map superimposed on the retinal image locates the edema in relation to retinal vessel landmarks, which may help determine where to apply focal laser photocoagulation.

Figure 4. Three-dimensional (3D) cube scans demonstrate the extent of the vitreomacular adhesion forces in both eyes.

The 3D images clearly explained why laser treatment was minimally effective in the treatment of DME and why VEGF inhibitors and steroids weren't a permanent solution. Severe traction on retinal vessels results in persistent leakage. The 3D scans indicated that vitreous traction played a major role in the patient's vision loss. Vitrectomy was indicated in this case to release the traction. In the future, we might consider an injection of microplasmin to cleave the bond between the vitreous and the retina, rather than performing a vitrectomy.

Superiority of Cirrus HD-OCT

This case clearly demonstrates how you can use Cirrus HD-OCT to develop a more accurate treatment plan for DME. We didn't appreciate the extent of the vitreous traction in either eye by viewing the high-resolution B-scans and topography maps. Laser photocoagulation, intravitreal steroids or VEGF-inhibitors probably won't offer a permanent solution for diabetic eyes with this much traction. This case emphasizes the clinical decision-making significance of Cirrus HD-OCT. OM