[Intravitreal injection. Monitoring to avoid postoperative complications]

Ability of Mn(2+) to Permeate the Eye and Availability of Manganese-enhanced Magnetic Resonance Imaging for Visual Pathway Imaging via Topical Administration

Background:

Manganese-enhanced magnetic resonance imaging (MEMRI) for visual pathway imaging via topical administration requires further research. This study investigated the permeability of the corneal epithelium and corneal toxicity after topical administration of Mn²⁺ to understand the applicability of MEMRI.

Methods:

Forty New Zealand rabbits were divided into 0.05 mol/L, 0.10 mol/L, and 0.20 mol/L groups as well as a control group (n = 10 in each group). Each group was further subdivided into epithelium-removed and epithelium-intact subgroups (n = 5 in each subgroup). Rabbits were given 8 drops of MnCl₂ in 5 min intervals. The Mn²⁺ concentrations in the aqueous and vitreous humors were analyzed using inductively coupled plasma-mass spectrometry at different time points. MEMRI scanning was carried out to image the visual pathway after 24 h. The corneal toxicity of Mn²⁺ was evaluated with corneal imaging and pathology slices.

Results:

Between the aqueous and vitreous humors, there was a 10 h lag for the peak Mn²⁺ concentration times. The intraocular Mn²⁺ concentration increased with the concentration gradients of Mn²⁺ and was higher in the epithelium-removed subgroup than that in the epithelium-intact subgroup. The enhancement of the visual pathway was achieved in the 0.10 mol/L and 0.20 mol/L epithelium-removed subgroups. The corresponding peak concentrations of Mn²⁺ were 5087 ± 666 ng/ml, 22920 ± 1188 ng/ml in the aqueous humor and 884 ± 78 ng/ml, 2556 ± 492 ng/ml in the vitreous body, respectively. Corneal injury was evident in the epithelium-removed and 0.20 mol/L epithelium-intact subgroups.

Conclusions:

The corneal epithelium is a barrier to Mn²⁺, and the iris and lens septum might be another intraocular barrier to the permeation of Mn²⁺. An elevated Mn²⁺ concentration contributes to the increased permeation of Mn²⁺, higher MEMRI signal, and corneal toxicity. The enhancement of the visual pathway requires an effective Mn²⁺ concentration in the vitreous body.

Incidence of damage to the crystalline lens during intravitreal injections

PURPOSE

To report the incidence of traumatic lens injuries as a complication of intravitreal injection at 5 high-volume academic centers.

METHODS

We determined in a retrospective, interventional, multicenter case series the consecutive number of the injections between January 5, 2006 and December 22, 2008 from the injection log books. All injections were performed under sterile conditions in a laying position, 3.5-4.0 mm behind the limbus in an oblique fashion. The main outcome measure was the incidence of lens damage.

RESULTS

A total of 32,318 intravitreal injections were performed, and 3 cases of iatrogenic lens damage were reported during 36 consecutive months. All affected eyes were hyperopic. The overall incidence rate of lens injury was 0.006% (2/32,318) for intravitreal injections and 1 during a paracentesis 0.003 (1/32,318). The rate of phakic eyes determined was 67%, and thus, the incidence rate of lens damage in phakic eyes was 0.009% (2/21,653) (95% confidence interval, 0.00%-0.05%).

CONCLUSIONS

Although there is no agreement regarding the proper intravitreal injection technique, the incidence of traumatic injuries to the crystalline lens was very low in a large series of injected patients in a community setting. The incidence compares favorably with that reported in clinical trials in which much more extensive preinjection preparation was mandated. A good preparation of the surgical incision with proper anesthesia and detailed information of the patient, as well as good anatomical skills of the treating physician, are mandatory to prevent this rare adverse event.

Incidence of rhegmatogenous retinal detachments after intravitreal antivascular endothelial factor injections

PURPOSE

To determine the incidence of rhegmatogenous retinal detachments (RD) after intravitreal injection in six high-volume centres.

METHODS

  A consecutive, interventional, multicenter case series measured the incidence of RD in patients receiving intravitreal anti-VEGF. A total of 35 942 intravitreal anti-VEGF injections (the number of the injections determined by review of injection log books over a 3 year period) were performed under sterile conditions with the patient in a supine position. Injections were given 3.5-4.0 mm behind the limbus in a tunnelled fashion.

RESULTS

During 36 consecutive months, five RD were reported, between 2 and 6 days after the injection. Of the affected eyes, four were myopic -1.75 to -5.5 dpt. The incidence rate of rhegmatogenous RD was 0.013% (5/35 942) per injection.

CONCLUSIONS

The incidence of RD in our community setting was very low (1 per 7188 injections). All RD occurred during the early postoperative period. The risks of RD can be minimized by a careful injection technique.

Choroidal detachment after an uneventful intravitreal injection

PURPOSE

The purpose of this report was to describe a case of choroidal detachment after an uneventful intravitreal injection using a 30-gauge needle.

METHODS

An 88-year-old patient with acute onset of neovascular age-related macular degeneration developed a choroidal detachment after an uneventful intravitreal injection in the infero-temporal aspect of the fundus.

RESULTS

The patient described no symptoms related to the chorioretinal detachment. Additional intravitreal injections were required to treat an active subfoveal choroidal neovascularization. These injections were placed at the contralateral side in the supero-nasal quadrant. She was closely watched on a 2-week follow-up schedule. The choroidal detachment remained asymptomatic for the patient and resolved spontaneously, and the best corrected visual acuity improved from 0.2 to 0.63 during a 6-month follow-up. A mild hyperpigmentation remained at this location.

CONCLUSION

Asymptomatic choroidal detachments may occur after intravitreal injection. Although treatment was not needed, additional injections should be avoided in the same quadrant until the detachment has resolved.

Evaluation of safety for bilateral same-day intravitreal injections of antivascular endothelial growth factor therapy

PURPOSE

To explore the incidence of complications after bilateral same-day intravitreal injections of antivascular endothelial growth factor pharmacotherapies in this retrospective interventional case series.

METHODS

An electronic review of billing records was performed to identify all bilateral same-day intravitreal antivascular endothelial growth factor injections performed within a single group retina practice between January 6, 2006 and June 1, 2009. The charts were reviewed to identify the complications of endophthalmitis, intraocular inflammation, retinal tear, and retinal detachment.

RESULTS

A total of 1,534 bilateral intravitreal injections (326 bevacizumab and 1,208 ranibizumab: 3,068 injections total) were performed in 367 patients. Three complications were identified. Two cases of unilateral culture-proven endophthalmitis occurred after bilateral intravitreal ranibizumab, and one case of unilateral acute intraocular inflammation occurred after bilateral intravitreal bevacizumab. In all three of these eyes, visual acuity returned to its preinjection level. No cases of retinal tear or retinal detachment were identified. The incidence of culture-proven endophthalmitis was 0.065%, and the incidence of acute intraocular inflammation was 0.033%.

CONCLUSION

The complication rates after bilateral same-day intravitreal antivascular endothelial growth factor injections seem to be similar to those after unilateral injections. Severe acute intraocular inflammation can occur unilaterally after same-day bilateral injections of bevacizumab.