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Anthony F. Kokx, Gary J. Miller; Three Methods of Topical Lidocaine-Based Anesthesia for Intravitreal Injections. Invest. Ophthalmol. Vis. Sci. 2012;53(14):473.
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The purpose of this study is to compare 3 different methods of topical anesthesia for intravitreal injections. This study will compare effectiveness of each method at achieving pre-injection anesthesia and each method's cost effectiveness.
Patients already requiring an intravitreal (0.05mL) injection with either Bevacizumab or Ranibizumab were enrolled in this study. Three different methods of topical anesthesia were utilized; 3.5% lidocaine gel (LG), 4% lidocaine soaked pledget (LP), and 4% lidocaine soaked cotton tipped applicator (CTA). Twenty-four patients were enrolled in the study (power of 80%), with all patients scheduled to receive each treatment arm. After each injection, a pain survey (100 point Visual Analog Scale) was administered, recording pain associated with both numbing and injection. The following day, the patients used the same scale to retrospectively rate their pain from the day of the injection as well as rate their residual pain (RP). Patients had no reference to the prior survey.
The average number of injections prior to enrollment in the study was 4.7. Average post-injection IOP was 30mm Hg. Subconjunctival hemorrhage (SCH) was noted in 1 out of 7 patients. The average pain score for each patient (all methods same day) associated with the numbing method was 6.5/100 (n=7); for the injection was 5.43/100 (n=7). The average pain score for each patient (all methods next day) associated with the numbing method was 6.8/100 (n=6); for the injection was 8.4/100 (n=6). The pain score in the LP group (n=5) was 5.8/100 for numbing and 3.5/100 injection (same day). The pain score in the LP group was 5.3/100 for numbing and 7.9/100 for injection (next day). The RP was 1.0/100. There was one SCH in this group that did not have higher retrospective or residual pain scores. The pain score in the LG group (n=1) was 0 for both numbing and injection (same and next day) without any RP. The pain score in the CTA group (n=1) was 16.5/100 for numbing and 18.5/100 injection (same day). The pain score in the CTA group was 7.5/100 for numbing and 6.0/100 injection (next day). RP was 1.5/100. There were no cases of endophthalmitis. The average unit cost for each method is as follows: LG $1.13 per injection; LP $0.80 per injection; CTA $0.24 per injection. Average staffing time for each numbing protocol; LG group - 10 seconds (for technician); LP group - 30 seconds (for technician); CTA group - 60 seconds (for physician).Data collection will finish March 2012.
All three anesthetic methods appear to be capable of achieving an effective level of anesthesia. Currently, there is not a link between SCH and higher RP or retrospective pain scores. There is a range of cost and time of staffing required with each method.
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