BY WILLIAM L. MILLER, OD, PHD, FAAO
Preventing the Destruction of Endophthalmitis
A tragic case of endophthalmitis recently caused the complete loss of an eye in a patient I had seen a few years ago. Although this struck close to home for me, many of you also directly or indirectly directly know patients who have suffered the insidious effects of endophthalmitis. This potentially blinding intraocular inflammation can lead to an eviscerative procedure, as was the case for my patient. It can result from surgery, trauma, intravitreal injections or endogenous seeding, from most to least common respectively. Although it most commonly occurs after cataract surgery, it can manifest after any ocular surgery.
Most sources cite an incidence of around 0.1 percent to 0.2 percent, although the frequency has increased in the 21st century for unknown reasons. A recent report shows that using a prophylaxis of fourth-generation fluoroquinolones prior to cataract surgery resulted in a rate of 0.07 percent.
Causes of Endophthalmitis
Most cases result from a coagulase negative Staphylococci and to a lesser extent from Staphylococcal aureus. Traumatic causes of endophthalmitis typically result from Staphylococci and B cereus and occur in 3 percent to 17 percent.
Over the last 10 years practitioners have increasingly used intravitreal injections, which present yet another avenue for bacteria to enter. Careful attention to aseptic technique is critical to preventing this vector for endophthalmitis. For example, during the VEGF Inhibition Study in Ocular Neovascularization (VISION), a protocol change toward stricter criteria for asepsis yielded lower rates of endophthalmitis.
Endogenous seeding occurs mostly in immunocompromised individuals. Fifty percent of such cases result from fungal organisms such as Candida albicans. Endogenous cases occur in only 2 percent to 8 percent of all endophthalmitis cases.
Presentation and Treatment
Patients can appear with acute or chronic cases of endophthalmitis, the former typically presenting with more virulent microorganisms and thus poorer prognosis. Your patient may experience varying levels of pain, decreased visual acuity, conjunctival hyperemia, corneal edema, vitritis, retinal hemorrhages and periphlebitis. The most common objective sign (86 percent) as found in the Endophthalmitis Vitrectomy Study is a hypopyon. Rapid identification of the condition with prompt referral is essential to offering an intervention that may save vision and the eye.
The differential diagnosis also includes uveitis and, more recently, toxic anterior segment syndrome. The latter also occurs in post-surgical cases, but the etiology (noninfectious and toxic) and treatment are different.
Treatment regimens are complicated by lack of knowledge of the particular offending agent, thus necessitating an empirical approach. Therapeutic options may include antibiotics such as vancomycin, aminoglycosides (amikacin) and cephalosporins (ceftazidime), most often delivered as an intravitreal injection. Concomitant intravitreal steroid use as a means to decrease the inflammatory effects of endophthalmitis remains controversial.
A vitrectomy serves as a means to remove the infectious component along with the simultaneous use of intravitreal antibiotics. This is especially true for cases of intraocular foreign body-induced endophthalmitis. Other modes of antibiotic treatment may include topical, oral, subconjunctival injection and intravenous. CLS
For references, please visit www.clspectrum.com/references.asp and click on document #137.
|Dr. Miller is the Director, Cornea and Contact Lens Service at the University of Houston College of Optometry. He is a member of the American Optometric Association and serves on its Journal Review Board. You can reach him at firstname.lastname@example.org.|