Talking May Increase the Risk of Streptococcal Infections after Intravitreal Injections

Dr. McCannel from UCLA presented an interesting paper at the annual meeting of American Academy of Ophthalmology in Chicago in October, 2010. He analyzed 16 articles published in the American medical literature from 2005 through 2009 on the topic of endophthalmitis (infection inside the eye) following intravitreal injections. As expected, endophthalmitis was rare, occurring in 54 of 105,531 injections. Only 26 were culture-positive, giving an incidence of 0.024%.

However, cultures yielded Streptococcus organisms 30.8% of the time (8 of 26), which Dr. McCannel said is "3- or 4-fold higher" than the incidence reported in the literature for acute postoperative endophthalmitis. The postoperative incidence of streptococcal endophthalmitis ranges from 0% after vitrectomy to 8.2% to 9% after cataract surgery, he reported.

Likely Source of Infection:

He found several studies in the anesthesia literature reporting streptococcal meningitis after dural puncture, a procedure that, according to Dr. McCannel, has a working distance between physician and patient similar to that of IVI. Analysis found that the causative organisms in most of those cases came from the treating physician's oral flora, which was aerosolized during talking.

Consequently, the Centers for Disease Control and Prevention in Atlanta, Georgia, recommended in 2007 that spinal procedure operators wear a surgical mask during the procedure (MMWR Morb Mortal Wkly Rep.2010;59:65-69).

Ophthalmologists "often have to give directions to the patient during injections, and sometimes there is small talk," Dr. McCannel said. "The patient's eye is probably being showered with these microscopic droplets. We may be contaminating the injection field or the needle.

Implications of the Study

1. Endophthalmitis is rare occurrence after intravitreal injections, which are commonly performed for age-related macular degeneration, diabetic macular edema, retinal vein occlusion and other conditions.
2. Streptococcal infections are more common after intravitreal injections compared to other intraocular procedures. Mouth is an important reservoir of streptococci.
   
3. Talking, coughing and sneezing should be minimized after the lid speculum has been placed to open the eye prior to administration of intravitreal injections.
4. If a surgeon needs to talk to the patient while administering intravitreal injections, he should turn his face away from the surgical field.
5. Although wearing a mask appears to be a good idea, it is not commonly done, including by the author of the study mentioned.
6. A surgeon should, however, be aware of the possibility of contamination of surgical field by talking, and should take steps to minimize it.
   

Healthy Diet and Exercise May Reduce the Risk of AMD

According to a study published in December, 2010 issue of the Archives of Ophthalmology, healthy eating habits and exercise may reduce the risk of age-related macular degeneration.

Investigators used data from the Carotenoids in Age-Related Eye Disease Study (CAREDS), part of the 1994-98 Women's Health Initiative Observation Study. The study included 1313 participants 55-74 years in age.

Requirements for a healthy diet included daily 3.5 servings of fruits and vegetables, 2.3 servings of dairy, 2.7 ounces of meat, poultry, fish, beans, or eggs, and 3.5 servings of grain, including one whole-grain item.

Presence of AMD was determined by fundus photographs, on average 6 years later.

Results

1. Women with highest quintile Healthy Eating Index had 46% reduction in the odds for early AMD.
2. Women in the highest quintile for physical activity demonstrated a 2-fold decrease in the odds for early AMD
3. Nonsmokers who ate the healthiest diets and were the most physically active (5% of the participants) reduced their odds for AMD by 71% compared to those with high risk scores.

Conclusion:

Adopting healthy diet and regular physical activity may markedly lower the risk of age-related macular degeneration.

Intravitreal triamcinolone for macular edema secondary to perfused central retinal vein occlusion

Central retinal vein occlusion (CRVO) is an important cause of vision loss. The 15-year cumulative incidence of CRVO was 0.5% in the Beaver Dam Study. Macular edema is a common cause of visual loss in CRVO. There is no proven treatment for macular edema from CRVO. Grid laser treatment showed anatomical improvement in CRVO study, but was not associated with visual improvement. Currently observation is considered standard of care in the management of macular edema secondary to CRVO. SCORE Study evaluated 4 mg and 1 mg triamcinolone acetonide (TA) injection against observation in a randomized clinical trial.

Methods: 271 patients with nonischemic CRVO were randomized to 4 mg or 1 mg intravitreal triamcinolone or observation. Mean duration of CRVO was 4 months, 40% had macular edema for less than three months. Mean visual acuity was 20/100 (range 20/40 to 20/400). Mean central point thickness by OCT was 659 microns. All eyes had less than 10 disk areas of capillary nonperfusion by fluorescein angiogram. Repeat injections were given every four months, if needed and patients were followed for at least one year.

Results. Both TA groups received an average of 2 injections prior to month 12. The percentage of patients gaining 3 or more lines of vision was 6.8%, 26.5% and 25.6% in observation, 1 mg and 4 mg TA groups respectively. Compared to a mean loss of vision of 12 letters in the control group, both TA groups had a mean loss of 1.2 letters of vision at 12 months. Percentage of patients losing three or more lines of vision was 44%, 25.3% and 25.6% respectively in observation, 1 mg and 4 mg TA groups respectively. All three groups had similar decrease in central point thickness by OCT. 35% and 20% eyes in 4 mg and 1 mg TA group respectively required IOP lowering medications. About 33% and 4% eyes in 4 mg and 1 mg TA group required cataract surgery by 24 months.

Conclusion: Both 4 mg and 1 mg TA intravitreal injections were superior to placebo. 1 mg TA was safer than 4 mg. About a quarter of patients in both TA groups gained three or more lines of vision, similar number lost three or more lines of vision and half the patients had central point macular thickness at 12 months. These results indicate that there is a need to develop a better treatment for macular edema caused by CRVO.

Intravitreal Steroid Injection in Branch Retinal Vein Occlusion

Branch retinal vein occlusion (BRVO) is a common retinal condition in which a branch of retinal vein gets blocked by a blood clot. As a result, the area drained by affected vein suffers from edema or swelling, bleeding, and poor blood circulation, called ischemia. If macula is affected, central vision is decreased or distorted. Macular edema is the most common cause of decreased vision in patients with BRVO.

Branch Vein Occlusion Study (BVOS) showed in 1984 that grid laser applied to the macular area in patients with BRVO and decreased central vision due to macular edema was superior to no treatment. Treated patients were about twice as likely to gain two or more lines of vision compared to observation.

Several additional treatments have been investigated for BRVO over the past few years. Intravitreal steroid, usually triamcinolone, is helpful in reducing macular swelling, but the benefit is short-term and several complications, most notably cataract and high intraocular pressure can result from steroid injections. Although 4 mg dose of triamcinolone has been used in most studies, it has been established that a dose as small as 1 mg is sufficient to saturate all steroid receptors in the eye.

SCORE study compared grid laser treatment with intravitreal injection of either 1 mg or 4 mg of triamcinolone. Retreatment was done every four months if needed for twelve months. At the end of one year period, all three treatment arms were about equally effective in improving vision, about 27% gaining three or more lines of vision compared to baseline. Loss of three lines or more of vision was observed in 10-15% patients and was comparable in all groups. Decrease in central foveal thickness was also comparable in all three groups at 12 months.Patients assigned to laser group received a mean of 1.8 treatments during the first year. Those assigned to steroid group received a mean of 2.2 treatments in 1 mg group and 2.1 treatments in 1 mg group.

Adverse events were higher in the steroid group, particularly those who received 4 mg dose, with 41% experiencing intraocular pressure high enough to require medications in that subset. Progression of cataract was more common in the steroid group; occurring in 25% in 1 mg group and in 35% in 4 mg group within in the first year. The investigators concluded that grid laser should remain the standard of care for patients with BRVO and decreased vision due to macular edema. The results were published in the September 2009 issue of Archives of Ophthalmology.

For additional information about retinal diseases including vein occlusion, diabetic retinopathy and macular degeneration visit http://www.illinoisretinainstitute.com/.