Volume 5, Number 51
Monday, December 26, 2005



In this issue: (click heading to view article)
Editorial: Medical Errors
Diagnostic Testing of Vitrectomy Specimens
Heritability of Macular Pigment: A Twin Study
Briefly











Editorial: Medical Errors

Over the past few years, I have offered care to or my opinion on four patients who experienced the consequences of medical errors. Two of these cases involved the entry of incorrect data into an excimer laser, resulting in an incorrect ablation and significant hyperopia. The other two resulted from IOL calculation errors. Fortunately, the errors in all cases were correctable by additional refractive procedures, and none ever went on to litigation. If I were to identify a common theme among these four cases, I’d say that it was a sincere regret on the part of the operating surgeon and a proactive behavior on his part to do anything necessary to benefit the patients concerned.

I regard the coming of the new year as an ideal opportunity for us to examine our own internal checks and balances to assure that we have taken all possible precautions against the likelihood of avoidable medical errors. We all know that sometimes errors will occur, but we can work to minimize their likelihood in every way we know how. The systems we put in place within our practices can never be too refined or perfected. Let’s put ourselves into the shoes of our patients and consider how frightening it is to realize that you’ve been a victim of a medical error--and let’s also put ourselves in the shoes of fellow colleagues who’ve made such errors and understand their horror as well. We must ensure that we’ve done everything we can to offer the highest quality of medical care for those who place their health and welfare in our hands.

Please accept my warmest wishes to all for a happy holiday season and for great peace and prosperity in the coming year.

Stephen E. Pascucci, MD
Medical Editor
[email protected]

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Review of Ophthalmology Online will not be published next week. Dr. Pascucci and the staff of ROO extend warmest wishes to you, your families and your staff members for a wonderful holiday and a healthy and productive new year!









Diagnostic Testing of Vitrectomy Specimens

Florida’s Bascom Palmer Eye Institute assessed the usefulness of diagnostic tests performed on vitrectomy specimens from patients with suspected lymphoma or infection.

The noncomparative, retrospective, interventional case series included 78 consecutive patients (84 eyes) who underwent pars plana vitrectomy for diagnostic purposes. Surgeons performed vitrectomy with cytologic, cytofluorographic or microbiologic analysis of vitreous samples. Main outcome measures were the efficiency of diagnostic procedure and positive and negative predictive values (PPV and NPV).

Twenty-eight patients (33 eyes) had suspected intraocular lymphoma, and 50 patients (51 eyes) had suspected infection; the latter was subdivided into chronic endogenous endophthalmitis, atypical chorioretinitis or chronic postoperative inflammation. Vitreous testing led to a diagnosis in 48 of 78 patients (61.5 percent); 14 patients with a final diagnosis of lymphoma/leukemia and 34 patients with a final diagnosis of infection. When preoperative indication was compared with final clinical diagnosis, the efficiencies of the diagnostic procedure of cytologic evaluation, flow cytometry and bacterial/fungal culture were 67 percent, 79 percent and 96 percent, respectively. For lymphoma, the PPV of cytologic evaluation was 100 percent and the NPV 60.9 percent. For infection, the PPV of bacterial/fungal culture was 100 percent and the NPV 94.9 percent. CD22(+) B lymphocytes 20 percent or higher of total cells on cytofluorographic analysis had a PPV of 88 percent for lymphoma. A cytofluorographic CD4:CD8 T-lymphocyte ratio of 4 or higher had a PPV of 70 percent for immunologically mediated uveitis. Surgical complications were rare and manageable.

The investigators concluded that diagnostic vitrectomy in selected patients with carefully planned testing is an effective means of supporting diagnoses in intraocular lymphoma, chronic intraocular infections and atypical chorioretinitis. Flow cytometry quantitates the percentages and ratios of various cell types and is helpful in contrasting intraocular lymphoma with immunologically mediated uveitis.

SOURCE: Davis JL, Miller DM, Ruiz P. Diagnostic testing of vitrectomy specimens. Am J Ophthalmol. 2005;140(5):822-29.
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Heritability of Macular Pigment: A Twin Study

Several studies have reported higher levels of macular pigment (MP) in association with reduced risk for age-related macular degeneration (AMD), a disease to which there is a genetic predisposition. Researchers in England, Ireland and the United States conducted a classic twin study to determine the heritability of MP in the healthy eye.

The study included 150 twin pairs, 76 of whom were monozygotic (MZ) and 74 of whom were dizygotic (DZ). The subjects ranged in age from 18 to 50 years. Researchers measured MP optical density psychophysically using heterochromatic flicker photometry (HFP) and an imaging method involving fundus autofluorescence (AF). They then compared the covariance of MP within MZ and DZ twin pairs, and they used genetic modeling techniques to determine the relative contributions of genes and environment to the variation in MP.

The mean MP optical density, measured using HFP, was 0.43 +/- 0.21. Using AF, the mean MP optical density, measured at 1 degrees eccentricity, was 0.28 +/- 0.11. MP optical densities correlated more highly in MZ twins than in DZ twins, according to both HFP (MZ: 0.65; DZ: 0.24) and AF (MZ: 0.83; DZ: 0.50). A model combining additive genetic and unique environmental effects provided the best fit and resulted in MP heritability estimates of 0.67 (95 percent CI, 0.52 to 0.77) and 0.85 (95 percent CI, 0.78 to 0.90) for HFP and AF readings, respectively.

The authors believe the results demonstrate that genetic background is an important determinant of MP optical density.

SOURCE: Liew SH, Gilbert CE, Spector TD, et al. Heritability of macular pigment: a twin study. Invest Ophthalmol Vis Sci. 2005;46(12):4430-6.
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BRIEFLY
  • EYETECH UPDATES TIMING OF EUROPEAN UNION APPROVAL FOR MACUGEN. The Committee for Medicinal Products for Human Use (CHMP), the scientific committee of the European Medicines Agency (EMEA), has advised Pfizer, Inc., Eyetech"s international marketing partner for Macugen (pegaptanib sodium injection), that it will issue an updated positive opinion recommending approval of Macugen for the treatment of wet age-related macular degeneration. The updated opinion is being issued to include updated label information related to rare occurrences of hypersensitivity during the administration of Macugen. It is unclear whether the hypersensitivity is associated with Macugen or the anesthetics and antibiotics that are co-administered with Macugen. Eyetech now anticipates European Union approval of Macugen in January 2006, and continues to plan a launch in the first quarter of 2006.
  • ALCON APPEALS PRO-AMO PATENT INFRINGEMENT RULING. Alcon, Inc. says it will appeal a patent infringement ruling in favor of Advanced Medical Optics, Inc. (AMO) handed down by a federal judge in Delaware. In the case, which was heard by a jury in 2005, AMO claimed Alcon infringed two U.S. patents, challenging certain features of Alcon"s Infiniti Vision System and the Advantec and Everest software upgrades to Alcon"s Legacy cataract system. By the new order, the court set damages at $213.9 million. Although the court granted AMO"s motion for an injunction, it also granted Alcon"s motion to stay the injunction pending the outcome of the appeal. Alcon will be able to continue to sell and distribute Infiniti vision systems and Infiniti FMS cassettes during the appeals process. It is also developing an alternative design of its Infiniti FMS cassette, which it expects to be available in the first half of 2006.
  • ALLERGAN SEEKS PRELIMINARY INJUNCTION AGAINST SALE OF GENERIC ACULAR. Allergan, Inc. has filed a motion with the United States District Court for the Northern District of California, San Francisco Division, requesting a temporary restraining order and preliminary injunction prohibiting the sale of a proposed generic version of Allergan"s non-steroidal anti-inflammatory drug Acular (ketorolac tromethamine ophthalmic solution 0.5% Allergan seeks the restraining order and injunction while the court conducts further proceedings in a patent infringement lawsuit brought by Allergan and Syntex (U.S.A.) LLC against Apotex, Inc.; Apotex Corp.; and Novex Pharma Inc. Acular is indicated for the temporary relief of ocular itching from seasonal allergic conjunctivitis and the treatment of post-operative inflammation in cataract surgery patients.
  • AKORN ANNOUNCES FDA INSPECTION RESULTS. In correspondence received on December 13 by Akorn, the FDA reported the satisfactory resolution of past cGMP issues at the company’s Decatur, IL, facility. The FDA says that the Decatur manufacturing facility is in compliance with current good manufacturing practice regulations. As a result of this inspection, Akorn is now eligible for new product approvals at the facility.


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