Book Review

Diabetic Retinopathy

N Engl J Med 2007; 357:312-313July 19, 2007

Article

Diabetic Retinopathy
(Developments in Ophthalmology. Vol. 39.) Edited by Gabriele E. Lang. 169 pp., illustrated. Basel, Switzerland, Karger, 2007. $180. ISBN: 978-3-8055-8243-8

Laser treatment has been available for more than 30 years, yet diabetic retinopathy remains the most important cause of visual loss among people of working age in developed countries — and increasingly in developing countries. Not surprisingly, a great effort is under way to find new ways to diagnose and treat this condition.

The editor and authors of this slim book set out to explain some of the pathogenic mechanisms that underlie diabetic retinopathy, new methods of assessment, new techniques for known methods of treatment, and new and possibly more effective treatments. Three chapters address macular edema, the most common cause of visual loss. These chapters are well researched and important, but they are somewhat difficult to read, and the authors of the first two chapters do not present any new ideas for treatment. The third chapter, a discussion of the use of intravitreal triamcinolone, includes a critical examination of a widely used method that still has not been tested in a major, well-controlled, long-term clinical trial. Reliable, quantitative methods of assessment would be needed to establish such a study.

The best chapter in the book (written by Gabriele Lang, the book's editor) is about optical coherence tomography, a relatively new method of imaging. This technique is a reliable, reproducible, quantitative assessment of macular edema but has not yet been accepted by the National Eye Institute as a definitive end point for clinical trials. José Cunha-Vaz has written an interesting chapter on proposed phenotypes in diabetic retinopathy, in which he describes new quantitative methods of assessment. These methods are time-consuming, and some are invasive, but they are helpful in clinical trials. The problem with Cunha-Vaz's three phenotypes is that we do not know how they evolved.

In her chapter on established laser treatments, Lang does not emphasize sufficiently that earlier treatment — possibly with the use of micropulsed lasers — yields better results with fewer side effects than do treatments reported in clinical trials. The chapter on vitreoretinal surgery emphasizes the new techniques and their much-improved outcomes. These results, together with the development of drugs used for vitreolysis, are exciting and bring hope to many patients.

New treatments are used almost exclusively in patients with sight-threatening lesions, and this is probably why such therapies are not uniformly successful. The chapter on the protein kinase inhibitor ruboxistaurin mesylate (also written by Lang) shows that the drug has probably been given too late in the evolution of retinopathy and, as a result, has been only partially effective. Lang quickly covers the biochemical pathway in a way that only experts will be able to understand. A diagrammatic explanation of the evolution of retinopathy would demonstrate that since the level of vascular endothelial growth factor is already elevated early in diabetic retinopathy, this is the time that ruboxistaurin (its inhibitor) should be given to prevent progression to sight-threatening retinopathy.

This book summarizes our understanding of diabetic retinopathy. It is useful for both internists and ophthalmologists who deal with diabetes and its complications, and should be read by all who intend to do research in the field of diabetic retinopathy.

Eva M. Kohner, M.D.
King's College London, London WC2R 2LS, United Kingdom
evakohner@gmail.com