Comparison of Three Different Anesthetic Approaches for Intravitreal Injections

This prospective, randomized, triple-armed trial compared the effectiveness of three different anesthetic approaches for intravitreal injections. Were included 92 consecutive patients scheduled to receive intravitreal injection of bevacizumab (Avastin, Genentech, Inc.) in one eye, from June 2014 to September 2014, evaluated at at a single center - Retina Clinic, Osasco, São Paulo, Brazil. The same ophthalmologist (CGA) administered both, anesthetic and therapeutic, injections. A masked nurse collected patient assessment responses and a masked statistician performed statistical analyses. The research followed the tenets of the Declaration of Helsinki and was approved by the Committee of Ethics in Research. All participants gave written informed consent prior to their participation.

Patients were randomized to 1 of 3 groups before injection: proparacaine 0.5% drops (Anestalcon®, Alcon Lab. do Brasil Ltda, São Paulo, Brazil), (Group Drops), proparacaine plus subconjunctival lidocaine 1% (Xylestesin®, Cristália, São Paulo, Brazil) (Group SC), or 2% lidocaine gel (Xylestesin®, Cristália, São Paulo, Brazil) (Group Gel).

A standardized method was used to prepare the injection site and disinfect the skin using povidone iodine 10%. Patients from groups Drops and SC received a drop of proparacaine 0.5% before receiving a drop of povidone iodine 5%. For the patients from Group Gel, the gel was placed on the eye before receiving the drop of povidone iodine 5%. Patients from Group Drops received a second drop of proparacaine 0.5%, 5 minutes after the drop of povidone iodine 5%. For the patients from Group SC, a subconjunctival bleb of anesthesia was created by injecting 0.4 ml of lidocaine 1% into the subconjunctival space, posteriorly to the superotemporal limbus with a 30-gauge, 1/2-inch needle attached to a 1-ml syringe. After 5 minutes of the drop of povidone iodine 5%, sterile field and a lid speculum were placed. The injection site was measured with calipers to be 3.5 mm or 4.0 mm posterior to the superotemporal limbus, for pseudophakic and phakic eyes, respectively. A 30-gauge 1/2-inch needle was used to inject 0.05 ml of bevacizumab (Avastin, Genentech, Inc.). After the injection, mild pressure was applied with a swabstick over the injection site to reduce vitreous reflux and subconjunctival hemorrhage another a drop of povidone iodine 5% was applied.

Immediately following the injection, a nurse, who was masked to the treatment, explained the 100-mm visual analog scale (VAS) for pain (Figure 1) and questioned the patients' level of pain perceived during the injection. This assessment was repeated 10 minutes, 1 hour, 6 hours and 24 hours later, without visualization of their prior responses. Patients were also asked to grade their overall experience with the injection procedure as Excellent (5), Very good (4), Fair (3), Poor (2) or Awful (1). The physician evaluated the patients' eye movement during intravitreal injection into three levels: none or minimal (0), not compromising the injection (1), compromising the injection (2). Complications that occurred during or after the procedures were also recorded.

Inclusion criteria

• Age: 18 years or older
• Indications for injection included neovascular AMD, DME and cystoid macular edema (CME) secondary to RVO.

Exclusion criteria

• Previous known allergic response to the topical anesthetics to be used.
• Previous intravitreal injections of drugs other than anti-VEGF agents
• Previous pars plana vitrectomy
• Anterior segment conditions that could affect pain sensation, such as conjunctival irritation, active conjunctivitis or keratitis or bullous keratopathy
• Patients using systemic analgesic or sedative medications