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Retinal Blood Flow and Macular Edema After Radial Optic Neurotomy for Central Retinal Vein Occlusion
Intravitreal Triamcinolone for the Treatment of Ischemic Macular Edema Associated With Branch Retinal Vein Occlusion
Retinal Blood Flow and Macular Edema After Radial Optic Neurotomy for Central Retinal Vein Occlusion EDITOR: WE READ WITH INTEREST THE ARTICLE BY HORIO AND ASSO-
EDITOR: I READ THE ARTICLE BY SIMON AND ASSOCIATES1 WHO
ciates.1 A control group with an adequate sample size is a must to prove that the changes in the retinal blood flow and macular thickness are actually due to procedure and not a consequence of the natural history of the disease. It is not clear whether the three patients whose visual acuity improved had ischemic or nonischemic central retinal vein occlusion.2 The video fluorescein angiography system that was used to measure the retinal blood flow with the dye dilution methods is not valid in patients with central retinal vein occlusion, because they do not have a closed vascular system.3 Also, in fluorescein angiography, papilledema, retinal edema, and hemorrhages block fluorescein intensities in major retinal vessels. In contrast, the use of indocyanine green angiography is influenced much less by the aforementioned factors.4 Perhaps the use of indocyanine green videoangiography may have been better. Delta T (50) shows the highest reproducibility to evaluate the mean retinal circulation time4 with the dye dilution method. The authors have not clarified which parameter they have chosen for estimating the mean retinal circulation time (RCT). All these factors related to the methodology may have contributed to inaccurate estimation of the post radial optic neurotomy retinal blood flow.4
prospectively studied 18 patients who had undergone intravitreal triamcinolene acetonide (IVTA) injection for ischemic macular edema with branch retinal vein occlusion (BRVO). They found that treatment with IVTA is useful in patients with ischemic macular edema, especially at one month. The authors stated that 47% of the patients gained 1 to 3 Snellen lines in visual acuity after the injection. The mean duration of BRVO before treatment was 14 months. When we look at the Figures in the article, the hemorrhages and edema and ischemia at the middle or long-time follow-up of ischemic BRVO are present, as expected. However, optimal coherence tomography results support the findings in the article. My opinion is that IVTA contributes only to the nonischemic part of the edema in these structures. I believe that the cortisone is not absolutely effective in the repair of capillary nonperfusion or ischemia. Therefore, these limited gains in visual acuity might be related to the resolution of the nonischemic edema, because there is no real effect of cortisone on any ischemia-reperfusion models. HAMDI ER, MD
NISHANT TANEJA, MD ANNIE MATHAI, MS, FRCS (ED)
Malatya, Turkey
Hyderabad, India REFERENCE
1. Chen SD, Sundaram V, Lochhead J, Patel CK. Intravitreal triamcinolone for the treatment of ıschemic macular edema associated with branch retinal vein occlusion. Am J Ophthalmol 2006;141:876 – 883.
REFERENCES
1. Horio N, Horiguchi M. Retinal blood flow and macular edema after radial optic neurotomy for central retinal vein occlusion. Am J Ophthalmol 2006;141:31–34. 2. Hayreh SS. Retinal vein occlusion. Indian J Ophthalmol 1994;42:109 –132. 3. Shuler RK Jr, Fekrat S. Does radial optic neurotomy alter retinal blood flow in eyes with a central retinal vein occlusion? Am J Ophthalmol 2006;141:145–146. 4. Nomoto H, Shiraga F, Yamaji H, et al. Evaluation of radial optic neurotomy for central retinal vein occlusion by indocyanine green videoangiography and image analysis. Am J Ophthalmol 2004;138:612– 619.
REPLY WE THANK DR ER FOR HIS INTEREST IN OUR STUDY. AS
stated in our report, we agree that the limited and transient gain in visual acuity that is experienced after intravitreal triamcinolone injection by some patients with ischemic macular edema that is associated with branch retinal vein occlusion is likely to be due to the resolution of macular edema that is induced by the triamcinolone rather than any direct beneficial effect on macular perfusion. SIMON D. M. CHEN, FRCOPHTH VENKI SUNDARAM, BM, BCH C. K. PATEL, FRCOPHTH
REPLY WE APPRECIATE THE INTEREST OF DRS TANEJA AND
Oxford, United Kingdom
Mathai in our study.1 They were concerned about the accuracy and reproducibility of our method for blood flow analysis. We and others2,3 have also been concerned with
JONATHAN LOCHHEAD, FRCOPHTH
Newport, Isle of Wight, United Kingdom 710
AMERICAN JOURNAL
OF
OPHTHALMOLOGY
OCTOBER 2006
Retinal Blood Flow and Macular Edema After Radial Optic Neurotomy for Central Retinal Vein Occlusion EDITOR: WE READ WITH INTEREST THE ARTICLE BY HORIO AND ASSO-
EDITOR: I READ THE ARTICLE BY SIMON AND ASSOCIATES1 WHO
ciates.1 A control group with an adequate sample size is a must to prove that the changes in the retinal blood flow and macular thickness are actually due to procedure and not a consequence of the natural history of the disease. It is not clear whether the three patients whose visual acuity improved had ischemic or nonischemic central retinal vein occlusion.2 The video fluorescein angiography system that was used to measure the retinal blood flow with the dye dilution methods is not valid in patients with central retinal vein occlusion, because they do not have a closed vascular system.3 Also, in fluorescein angiography, papilledema, retinal edema, and hemorrhages block fluorescein intensities in major retinal vessels. In contrast, the use of indocyanine green angiography is influenced much less by the aforementioned factors.4 Perhaps the use of indocyanine green videoangiography may have been better. Delta T (50) shows the highest reproducibility to evaluate the mean retinal circulation time4 with the dye dilution method. The authors have not clarified which parameter they have chosen for estimating the mean retinal circulation time (RCT). All these factors related to the methodology may have contributed to inaccurate estimation of the post radial optic neurotomy retinal blood flow.4
prospectively studied 18 patients who had undergone intravitreal triamcinolene acetonide (IVTA) injection for ischemic macular edema with branch retinal vein occlusion (BRVO). They found that treatment with IVTA is useful in patients with ischemic macular edema, especially at one month. The authors stated that 47% of the patients gained 1 to 3 Snellen lines in visual acuity after the injection. The mean duration of BRVO before treatment was 14 months. When we look at the Figures in the article, the hemorrhages and edema and ischemia at the middle or long-time follow-up of ischemic BRVO are present, as expected. However, optimal coherence tomography results support the findings in the article. My opinion is that IVTA contributes only to the nonischemic part of the edema in these structures. I believe that the cortisone is not absolutely effective in the repair of capillary nonperfusion or ischemia. Therefore, these limited gains in visual acuity might be related to the resolution of the nonischemic edema, because there is no real effect of cortisone on any ischemia-reperfusion models. HAMDI ER, MD
NISHANT TANEJA, MD ANNIE MATHAI, MS, FRCS (ED)
Malatya, Turkey
Hyderabad, India REFERENCE
1. Chen SD, Sundaram V, Lochhead J, Patel CK. Intravitreal triamcinolone for the treatment of ıschemic macular edema associated with branch retinal vein occlusion. Am J Ophthalmol 2006;141:876 – 883.
REFERENCES
1. Horio N, Horiguchi M. Retinal blood flow and macular edema after radial optic neurotomy for central retinal vein occlusion. Am J Ophthalmol 2006;141:31–34. 2. Hayreh SS. Retinal vein occlusion. Indian J Ophthalmol 1994;42:109 –132. 3. Shuler RK Jr, Fekrat S. Does radial optic neurotomy alter retinal blood flow in eyes with a central retinal vein occlusion? Am J Ophthalmol 2006;141:145–146. 4. Nomoto H, Shiraga F, Yamaji H, et al. Evaluation of radial optic neurotomy for central retinal vein occlusion by indocyanine green videoangiography and image analysis. Am J Ophthalmol 2004;138:612– 619.
REPLY WE THANK DR ER FOR HIS INTEREST IN OUR STUDY. AS
stated in our report, we agree that the limited and transient gain in visual acuity that is experienced after intravitreal triamcinolone injection by some patients with ischemic macular edema that is associated with branch retinal vein occlusion is likely to be due to the resolution of macular edema that is induced by the triamcinolone rather than any direct beneficial effect on macular perfusion. SIMON D. M. CHEN, FRCOPHTH VENKI SUNDARAM, BM, BCH C. K. PATEL, FRCOPHTH
REPLY WE APPRECIATE THE INTEREST OF DRS TANEJA AND
Oxford, United Kingdom
Mathai in our study.1 They were concerned about the accuracy and reproducibility of our method for blood flow analysis. We and others2,3 have also been concerned with
JONATHAN LOCHHEAD, FRCOPHTH
Newport, Isle of Wight, United Kingdom 710
AMERICAN JOURNAL
OF
OPHTHALMOLOGY
OCTOBER 2006