Retinal Treatments

MAY 12, 2010
by Sharon Terry, Executive Director, PXE International
and by Christine Vocke, Director of Education and Information, PXE International

There is a great deal more hope for individuals affected by pseudoxanthoma elasticum (PXE) when they experience choroidal neovascularization (CNV) than there has been in prior decades. The story of a person experiencing retinal bleeding (CNV) in the last century was not a good one. Typically they experienced a bleed and their ophthalmologist used all of the available treatments, beginning with ‘hot´ laser therapy, then eventually photodynamic laser therapy, and even some tried rotating the retina, trimming blood vessels and other experimental therapies. In recent years, the advent of anti-VEGF therapies, originally developed in cancer therapy, has given both patients and providers great hope. In the Summer 2009 MemberGram, we reported on these advances, specifically on two commonly used therapies, Avastin® and Lucentis®.

As usual, most of the papers written on Avastin and Lucentis over the past few months have been about age related macular degeneration (AMD), diabetic retinopathy or other conditions. For example, a review of 14 studies on the use of intravitreal bevacizumab (Avastin) or ranibizumab (Lucentis) for more than 250 patients with CNV due to pathologic myopia showed significant improvement of visual acuity and an excellent safety profile [1]. This continues to be good news for people with AMD and PXE.

Very few papers have been written on the effect of these treatments on pseudoxanthoma elasticum, and these papers usually report on very few patients. A recent study [2] reported on the long-term results of these therapies in people with pseudoxanthoma elasticum. In this study, one eye in each of nine patients was treated. The article reports on a follow-up time of 28.6 months. During this time, these nine eyes received an average of 8.4 injections. When the study began, the mean visual acuity was 20/368 (median, 20/60) and improved to 20/281 (median, 20/40) at the last visit. (Ed. comment: A mean is an average, and a median is the middle number. So in this case, when the study started, four people had better than 20/60 vision and five had between 20/60 and legal blindness, which is greater than 20/400. When the study ended, the average was 20/281, and at that point five eyes were 20/40 or better, and the rest had lower visual acuity. You can see in these small samples, a few very large numbers can drastically change the average.) Visual acuity either improved or stabilized in all nine eyes. The paper concluded that “continued experience with intravitreal bevacizumab or ranibizumab in this population will help establish long-term efficacy and better define optimal dosing strategies.”

Another recent paper [3] also reported long-term results of Avastin injections in 15 eyes of people with CNV and angioid streaks who had not had any previous treatment. The mean follow-up time was 19 months (range of 12 to 24 months). In this study, the mean visual acuity improved in five eyes (33%), was unchanged in eight eyes (54%) and decreased in two eyes (13%). New or recurring CNV was seen in half of the eyes during the follow-up times of up to a year. Additional injections of Avastin stabilized these eyes. This paper concluded, “An intravitreal injection of bevacizumab seems to maintain visual acuity. However, CNV frequently recurred or new CNV developed during the long followup.” These results illustrate the importance of periodic monitoring of patients with angioid streaks and CNV. It is not clear, though it is likely, that the individuals with angioid streaks had pseudoxanthoma elasticum.
 

References

[1] Cohen SY, Anti-VEGF Drugs as the 2009 First-Line Therapy for Choroidal Neovascularization in Pathologic Myopia, Retina 29, 1062 (Sep 2009). PMID: 19734760

[2] Myung JS, Bhatnagar P, Spaide RF, Klancnik JM, Cooney MJ, Yannuzzi LA, Bailey Freund K, Long-Term Outcomes of Intravitreal Antivascular Endothelial Growth Factor Therapy for the Management of Choroidal Neovascularization in Pseudoxanthoma Elasticum, Retina (Dec 4, 2009). PMID: 19996818

[3] Sawa M, Gomi F, Tsujikawa M, Sakaguchi H, Tano Y, Long-term Results of Intravitreal Bevacizumab Injection for Choroidal Neovascularization Secondary to Angioid Streaks, Am J Oththalmol 148, 584 (Oct 2009). PMID: 19541288