Volume 8, Number 24
Monday, June 16, 2008



In this issue: (click heading to view article)
Association of Plasma Homocysteine and Macular Edema in Type II Diabetes
Preoperative Keratometry and Residual Spherical Equivalent after LASEK
Effectiveness of Intensive Medical Therapy vs. Islet Cell Transplantation for DR
Comparison of Hemodynamic Parameters in Retrobulbar Vessels in PXS and PXG
Briefly





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Association of Plasma Homocysteine and Macular Edema in Type II Diabetes

Hyperhomocysteinemia may be one of the crucial risk factors for the development of macular edema (ME), according to the results of a Turkish cross-sectional study.

The study included 65 diabetic subjects with no retinopathy and nonproliferative diabetic retinopathy (NPDR) (no DR, 16; without ME, 25; with ME, 24), 28 with proliferative diabetic retinopathy (PDR) (with ME, 14; without ME, 14) and 19 healthy subjects as control. Investigators determined plasma homocysteine, vitamin B12, vitamin B6 and folate levels after eight hours of fasting for all subjects. Serum homocysteine and vitamin B6 levels were measured using high-performance liquid chromatography with fluorescence detection, and the levels of serum vitamin B12 and folic acid were measured using electrochemiluminescence immunoassay.

When diabetic groups with ME were compared with diabetic groups without ME for homocysteine, vitamin B12, vitamin B6 and folic acid, the only significant difference was detected in homocysteine levels. There was no significant difference between the NPDR with ME group compared to the NPDR without ME group and the no DR group for plasma homocysteine, vitamin B12, vitamin B6 and folic acid. When the PDR with ME group was compared to the PDR without ME group, the only significant difference occurred in homocysteine levels.

The authors believe that mild-to-moderate elevation of homocysteine may explain the role of vascular dysregulation and endothelial dysfunction in patients with DR.


SOURCE: Aydin E, Demir HD, Ozyurt H, Etikan I. Association of plasma homocysteine and macular edema in type 2 diabetes mellitus. Eur J Ophthalmol 2008;18(2):226-32.
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Preoperative Keratometry and Residual Spherical Equivalent after LASEK

Researchers in Spain conducted a retrospective study to examine the relationship between preoperative keratometry and residual spherical equivalent (SE) after myopic laser-assisted subepithelial keratectomy (LASEK).

The study included 1,149 consecutive eyes that underwent LASEK to correct myopia. Investigators used linear regression analysis to determine the relationship between preoperative keratometry and the three-month postoperative SE. They performed the same type of analysis in the first decile (percentile 10) with the flattest keratometry readings in the decile with the steepest readings and in the quartiles with the lowest and highest preoperative myopia.

Preoperatively, the mean SE was -4.59 D ± 2.80 (SD) (range, -0.25 D to -13.00 D) and the mean keratometry was 44.20 ± 1.60 D (range, 39.00 D to 49.00 D). Three months postoperatively, the mean SE was +0.05 D ± 0.50 D. There was a significant but weak correlation between the mean preoperative keratometry and residual SE. Linear regression showed a positive significant correlation within each decile. The correlation was weak in the decile with the flattest corneas (115 eyes) and slightly stronger in the decile with the steepest corneas (115 eyes); that is, the steeper the cornea, the greater the overcorrection. Researchers also found a weak correlation in the group with higher preoperative myopia, but no correlation in the lower myopia group. They concluded that preoperative corneal curvature does not appear to influence the spherical refractive outcomes after myopic LASEK.

SOURCE: de Benito-Llopis L, Teus MA, Sanchez-Pina JM, Gil-Cazorla R. Influence of preoperative keratometry on refractive results after laser-assisted subepithelial keratectomy to correct myopia. J Cataract Refract Surg 2008;34(6):968-73.
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Effectiveness of Intensive Medical Therapy vs. Islet Cell Transplantation for DR

The British Columbia islet transplant program at the University of British Columbia has been conducting a prospective crossover study comparing medical therapy and islet cell transplantation on the progression of diabetic retinopathy (DR). The study presents the results of an interim data analysis performed after a mean 36-month follow-up post-islet transplantation.

Progression was defined as the need for laser treatment or a one-step worsening along the international disease severity scale. The medical and post-islet transplant groups were similar at baseline. Subjects after islet transplantation had better glucose control than the medically treated subjects (mean HbA1c 6.7 percent ± 0.9 percent vs. 7.5 ± 1.2) and were C-peptide positive. Progression occurred significantly more often in all subjects in the medical group (10 of 82 eyes, 12.2 percent) than after islet transplantation (0 of 51 eyes, 0 percent). Considering only subjects who have received transplants, progression occurred in 6 of 51 eyes while on medical treatment and 0 of 51 post-transplant.

Based on these interim results, the investigators concluded that progression of DR is more likely to occur during medical therapy than after islet cell transplantation.

SOURCE: Thompson DM, Begg IS, Harris C, et al. Reduced progression of diabetic retinopathy after islet cell transplantation compared with intensive medical therapy. Transplantation 2008;85(10):1400-05.
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Comparison of Hemodynamic Parameters in Retrobulbar Vessels in PXS and PXG

A prospective, cross-sectional study compared the hemodynamic parameters in the retrobulbar vessels in pseudoexfoliative syndrome (PXS), pseudoexfoliative glaucoma (PXG) and age-matched healthy subjects using color Doppler imaging. The study included 72 eyes from 72 patients with PXS, 70 eyes from 70 patients with PXG and 66 eyes from 66 age-matched healthy subjects who met the inclusion/exclusion criteria. Peak systolic velocity, end-diastolic velocity and Pourcelot resistance index (RI) were assessed in the ophthalmic artery, central retinal artery and temporal short-posterior ciliary arteries. Investigators assessed visual function using the 24-2 Swedish Interactive Threshold Algorithm (SITA).

The end-diastolic velocity in the ophthalmic artery, short-posterior ciliary arteries and central retinal artery was decreased significantly in the eyes of PXG patients compared with that of control participants and PSX patients. The RI in the ophthalmic artery, short-posterior ciliary arteries and the central retinal artery was significantly higher in the eyes of PXG patients compared with that of healthy controls and PSX patients. The mean difference in mean end-diastolic velocity in the ophthalmic artery between the control group and the PXS was 0.18 cm/s; the mean difference in mean end-diastolic velocity in the short-posterior ciliary arteries between the control healthy subjects and the pseudoexfoliative subjects was -0.18 cm/s. Multivariate regression analysis showed that in the PXG patients, the peak systolic velocity and end-diastolic velocity in the central retinal artery were significantly positively correlated with the mean defect. The RI in the central retinal artery was significantly negatively correlated with the mean defect in PXG patients.

The results of this study showed that the retrobulbar hemodynamics might be disturbed in patients with PXG, especially in the central retinal artery. The study authors found no significant differences in the retrobulbar hemodynamic parameters between PXS patients and age-matched healthy subjects.

SOURCE: Martinez A, Sanchez M. Retrobulbar hemodynamic parameters in pseudoexfoliation syndrome and pseudoexfoliative glaucoma. Graefes Arch Clin Exp Ophthalmol 2008; May 20. [Epub ahead of print].
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BRIEFLY
  • SANTEN AND MACUSIGHT COLLABORATE ON SIROLIMUS FOR TREATING OCULAR DISEASES. Santen Pharmaceutical Co. and MacuSight have entered into a research and development collaboration and license agreement for the Japanese and Asian development and commercialization of sirolimus for treating ocular diseases and conditions such as wet AMD and DME. Sirolimus, originally known as rapamycin, is a potent, broad-acting compound that has demonstrated the ability to combat a broad range of diseases and conditions through multiple mechanisms of action including immunosuppressive, anti-angiogenic, anti-migratory, anti-proliferative, anti-fibrotic and anti-permeability activity. MacuSight is initiating a Phase II clinical trial of the compound for DME and is planning to initiate a Phase II study of the compound for treating wet AMD in the second half of 2008. Under terms of the agreement, Santen receives rights to develop and commercialize sirolimus for ocular diseases and conditions in Japan and Asia; MacuSight retains development and commercialization rights to sirolimus in all other markets. Specific financial details of the agreement have not been disclosed, but Santen has agreed to provide MacuSight with an initial upfront payment of $50 million for funding the latter"s continuing research and development efforts, as well as clinical development of sirolimus. Additionally, Santen will provide MacuSight with milestone payments and a royalty on future sirolimus sales in the Japanese and Asian markets.
  • TOPCON INTRODUCES WEB-BASED LINK TO SPECTRAL DOMAIN OCT IMAGING SYSTEMS. Topcon Medical Systems has introduced the EyeRoute Image Management System, a web interface tailored specifically for Spectral Domain OCT imaging systems. It includes dynamic interfaces for the Topcon 3D OCT-1000 and the Heidelberg Spectralis; interfaces for Cirrus, Optovue and Zeiss are in production. The system allows an eyecare practitioner to log in to EyeRoute and view his or her Spectral Domain OCT system via the Internet (it is no longer necessary to have the OCT review station software loaded onto a PC). Enhanced functionality includes Pin-Point display of the OCT image and its corresponding fundus image and dynamic viewing of the B-scan movie in real time. The user can view and manipulate a variety of images, including B-scans, digital retinal images and visual fields, and then directly compare them to the 3D OCT images. For more information, go to www.topconmedical.com.
  • AKORN RECEIVES NDA APPROVABLE LETTER FOR OCULAR TOPICAL ANESTHETIC. The FDA has sent an approvable letter to Akorn, Inc. for the company"s Akten Ophthalmic Gel 3.5%, an ocular topical anesthetic. The letter identified several minor CMC deficiencies that must be addressed before the FDA grants final approval; no additional clinical data is required. Akorn has also received proposed labeling from the FDA and intends to submit final printed labeling immediately.


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