Volume 6, Number 12
Monday, March 27, 2006



In this issue: (click heading to view article)
Effect of Aspirin and Warfarin Therapy in Trabeculectomy
Long-Term Effect of Laser Treatment for Dry AMD on Choroidal Hemodynamics
Impact of Refractive Correction on Quality of Life
IOP Changes in HIV Patients Treated with Highly Active Antiretroviral Therapy
Briefly











Effect of Aspirin and Warfarin Therapy in Trabeculectomy

The management of patients on antiplatelet and anticoagulation therapy (APACT) in glaucoma surgery currently has no specific recommendations. In this study, investigators in Scotland aimed to establish the risk of hemorrhagic complications and surgical outcome in patients on APACT in glaucoma surgery.

The investigators retrospectively examined 367 consecutive trabeculectomies performed between 1994 and 1998. Preoperatively, 60 patients(16.4 percent) were on APACT (55 on aspirin and 5 on warfarin). The incidence of hyphema and hemorrhagic complications between patients with and without APACT was documented. Surgical success was defined in two categories as an intraocular pressure (IOP) less than 21 mm Hg and an IOP less than 16 mm Hg two years following trabeculectomy with and without antiglaucoma medication.

None of the patients on aspirin suffered significant intra- or postoperative hemorrhage. Aspirin was associated with a significantly higher risk of hyphema, but this was not found to significantly affect IOP control at two years. Patients on warfarin suffered hemorrhagic complications and trabeculectomy failure.

The authors concluded that aspirin therapy appears to be safe to continue during trabeculectomy; although patients on aspirin have an increased risk of hyphema following trabeculectomy, this does not appear to affect surgical outcome. Warfarinized patients are at risk of serious bleeding complications, however. They require careful monitoring pre- and postoperatively, and they are at risk of trabeculectomy failure.

SOURCE: Cobb CJ, Chakrabarti S, Chadha V, Sanders R. The effect of aspirin and warfarin therapy in trabeculectomy. Eye 2006; Mar 3 [Epub ahead of print].
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Long-Term Effect of Laser Treatment for Dry AMD on Choroidal Hemodynamics

Investigators at the Scheie Eye Institute, Philadelphia, PA, aimed to determine whether laser treatment applied according to the Complications of Age-Related Macular Degeneration Prevention Trial (CAPT) has an effect on choroidal circulation.

The randomized, controlled study included 30 CAPT patients with bilateral drusen. Researchers used laser Doppler flowmetry to measure relative choroidal blood flow (Ch(flow)) in the fovea. They obtained measurements through dilated pupils in both eyes of each patient before photocoagulation was applied in one eye. Measurements were repeated at three months (30 patients) and 28 months (23 patients).

Average Ch(flow) at baseline, three months and 28 months was 7.2 +/- 2.1 (+/- 1 SD), 7.3 +/- 2.5 and 6.8 +/- 2.7 arbitrary units (AU) in the control eyes, and 6.6 +/- 1.6, 7.0 +/- 2.3 and 7.8 +/- 3.0 AU in the treated eyes. Compared to control eyes, no significant change in Ch(flow) was evident in the treated eyes at three months after treatment. At 28 months, however, there was a 5.6 percent drop in Ch(flow) in control eyes and an 18.2 percent increase in Ch(flow) in treated eyes from baseline. The average difference of 23.8 percent between the percentage changes in Ch(flow) observed in the control and treated eyes was statistically significant.

The authors believe that the increase in choroidal blood flow 28 months after laser treatment according to the CAPT protocol may play a role in the mechanism leading to the disappearance of drusen after photocoagulation. However, whether removal of drusen after photocoagulation is beneficial to the patients is not known at this time.

SOURCE: Figueroa M, Schocket LS, Dupont J, et al. Long-term effect of laser treatment for dry age-related macular degeneration on choroidal hemodynamics. Am J Ophthalmol 2006; Mar 7 [Epub ahead of print].
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Impact of Refractive Correction on Quality of Life

The Quality of Life Impact of Refractive Correction (QIRC) questionnaire is an effective outcome measure for quality-of-life impact of refractive correction by spectacles, contact lenses or refractive surgery in pre-presbyopic patients, according to an Australian study.

The 20-item QIRC questionnaire was administered to 312 participants: 104 were spectacle wearers, 104 were contact lens wearers and 104 had undergone refractive surgery. The three groups were similar for gender, ethnicity, socioeconomic status and refractive error. The main outcome measure was QIRC overall score (from 0 to 100), a measure of refractive correction related to quality of life. Groups were compared for overall QIRC score and on each question by analysis of variance, adjusted for age, with post hoc significance testing (Sheffe).

On average, refractive surgery patients scored significantly better than contact lens wearers, who in turn scored significantly better than spectacle wearers. Convenience questions chiefly drove the differences between groups, although functioning, symptoms, economic concerns, heath concerns and well-being were also important. Spectacle wearers with low-strength prescriptions scored significantly better than those with medium-strength prescriptions. Seven participants (6.7 percent of refractive surgery patients) experienced postoperative complications, which had an impact on quality of life.

SOURCE: Pesudovs K, Garamendi E, Elliott DB. A quality of life comparison of people wearing spectacles or contact lenses or having undergone refractive surgery. J Refract Surg 2006;22(1):19-27.
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IOP Changes in HIV Patients Treated with Highly Active Antiretroviral Therapy

The Shiley Eye Center, La Jolla, CA, characterized a longitudinal relationship between highly active antiretroviral therapy immune recovery, defined by an increase in CD4 cell counts and any associated changes in intraocular pressure (IOP) in patients with and patients without a history of cytomegalovirus (CMV) retinitis. They also aimed to determine if human immunodeficiency (HIV)-induced reduction in IOP is reversible.

The retrospective analysis of patient data collected from 1997 through 2004 included patients from one eye center, including patients from the Longitudinal Study of Ocular Complications of Acquired Immunodeficiency Syndrome. Investigators conducted linear regression analyses within the CMV and non-CMV groups to determine the change in IOP per 100-unit change in CD4 count. Average changes in IOP per change in CD4 count were compared between the CMV and the non-CMV groups using a Wilcoxon rank-sum test. Linear regression analyses were conducted within the CMV and non-CMV groups to determine the linear relationship between the 12-month change in IOP per 12-month 100-unit change in CD4 count.

Compared with the non-CMV group, the median IOP change per change in CD4 count was not statistically different from the CMV group (0.9 mm Hg vs. 1.7 mm Hg per 100 CD4 cells, respectively). Analysis of the linear relationship between the 12-month change in IOP and the 12-month change in CD4 count within both the CMV and non-CMV groups showed a strong linear relationship: 67 percent of the variability in a 12-month IOP change for the CMV group and 36 percent of the variability in a 12-month IOP change for the non-CMV group. The authors concluded that reduction in T-lymphocyte count in HIV infection is accompanied by a decrease in IOP in CMV-infected and non-CMV-infected eyes, and that immune recovery is associated with an increase in IOP.

SOURCE: Kozak I, LaBree L, Azen SP, et al. Long-term study of intraocular pressure changes in patients with human immunodeficiency virus treated with highly active antiretroviral therapy. Ophthalmol 2006;113(3):451-5.
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BRIEFLY
  • LONG-TERM LINEZOLID ASSOCIATED WITH RARE CASES OF OPTIC NEUROPATHY The antimicrobial agent linezolid, used to treat chronic and recurrent infections of the blood, lungs and skin, may cause reversible or irreversible optic neuropathies if taken for longer than five months, suggests a study in the most recent issue of Neurology. The authors of the study point out that although there appears to be an association between linezolid and optic neuropathies, the incidence of optic neuropathies seems extremely rare, especially since linezolid is commonly prescribed for no more than 28 days for treating Gram-positive bacterial infections. The study reports on three patients who were treated with linezolid for five to 10 months and developed progressive, painless loss of vision. Investigators ruled out hereditary and nutritional causes for the vision loss; examination suggested optic neuropathies. When the linezolid treatment was discontinued, the patients’ vision improved. The study also reviewed nine previous cases in which patients treated with linezolid for a similar length of time developed optic neuropathies, which were also partly resolved after discontinuing treatment. The authors believe long-term linezolid treatment can induce reversible optic neuropathies but may also cause irreversible peripheral damage.

    SOURCE: Rucker JC, Hamilton SR, Bardenstein D, et al. Linezolid-associated toxic optic neuropathy. Neurology 2006;66:595-8.
  • FDA APPROVES BAUSCH & LOMB’S ZYOPTIX EXCIMER LASER. The FDA has approved Bausch & Lomb’s 100-Hertz excimer laser, the 217z100, for use in the United States as part of its Zyoptix Personalized Laser Vision Correction System for refractive surgery. The new excimer laser operates at twice the speed of the B&L system currently on the U.S. market in standard and custom treatment modes; it is expected to be commercially available in the United States by July 2006, along with an upgrade path to allow current users of the Zyoptix laser to access the faster technology. For more information, go to www.bausch.com.
  • INTRAOCULAR IMPLANTS SHOW PROMISE FOR TREATING RETINAL DISEASE. The results of a Phase I trial by the National Institutes of Health suggests that ciliary neurotrophic factor (CNTF) delivered with encapsulated cell intraocular implants may be a safe and effective means of improving visual acuity in patients with retinal degeneration. CNTF has been shown to slow retinal degeneration in animal models. Researchers delivered CNTF by incorporating its gene into cells placed in a semi-permeable capsule; the capsule was implanted into the vitreous of a disease-affected eye in 10 subjects. The capsules were removed after 6 months. In all cases, viable cells produced CNTF quantities that were therapeutic in animals. The study was not intended to evaluate efficacy, but 3 of 7 eyes in the study showed clinically relevant improvements in visual acuity. In all but one case of choroidal detachment (which resolved using conservative therapy), the implant procedure and presence of the cell capsule appeared to be safe and well-tolerated. The researchers conducting the study believe that the method holds promise for applications beyond diseases that are caused by genetic mutations.


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