The retrobulbar block anesthesia efficacy in ophthalmic surgical interventions in patients with Asian and European upper eyelid structures

BACKGROUND: Retrobulbar block (RBB) is known to be accompanied by upper eyelid edema of varying degrees is associated with moderate exophthalmos, which can adversely affect surgical conditions. It was hypothesized that differences in the anatomy of the ocular adnexa between patients of Asian and European descent may determine the different severity of edema following retrobulbar block administration.

AIMS: To assess the effectiveness of RBB and the surgeon's comfort during surgery in patients with Asian and European eyelid structures.

MATERIALS AND METHODS: A prospective cotrolled study was conducted involving 80 patients aged 51 to 75 years who underwent retrobulbar block analgesia during vitreoretinal surgery. Group 1 (n=40) consisted of patients with European eyelid anatomy, and Group 2 (n=40) included patients with Asian eyelid anatomy. Changes in intraocular pressure, upper eyelid thickness at various stages of block administration, preparation time for surgery, levels of analgesia, akinesia, and surgeon’s comfort were evaluated.

RESULTS: In Group 1, patients exhibited an increase in upper eyelid thickness of 0.9 ± 0.1 mm, compared to 2.8 ± 0.4 mm in Group 2 (p < 0.001), attributable to infiltration of postseptal soft tissues by the local anesthetic. Mean akinesia scores were 1.0 ± 0.2 and 1.4 ± 0.6 for Groups 1 and 2, respectively (p = 0.021), with higher scores reflecting diminished akinesia efficacy.

Following retrobulbar block (RB), intraocular pressure (IOP) in Group 1 rose to 17.6 ± 1.9 mmHg but returned to baseline (15.9 ± 1.9 mmHg) after orbital compression. In contrast, Group 2 demonstrated a significant IOP elevation post-RB (24.9 ± 6.3 mmHg; p < 0.001) and post-compression (21.5 ± 5.4 mmHg; p < 0.001), both exceeding baseline levels (16.2 ± 1.3 mmHg). Ocular hypertension necessitated prolonged preoperative preparation for IOP reduction in 5% of Group 1 and 28.75% of Group 2 patients.

Pain assessment revealed a mean VAS score of 2.6 ± 1.3 in Group 2, significantly higher than Group 1's 1.6 ± 1.5 (p < 0.001), prompting supplemental intraoperative parenteral analgesia. Surgeon comfort was compromised in Group 2 due to a reduction in palpebral fissure width from 21.4 ± 1.1 mm to 14.8 ± 1.9 mm post-RB, correlated with anesthetic infiltration of the upper eyelid.

CONCLUSIONS: Retrobulbar block in patients with Asian upper eyelid anatomy was associated with a significant increase in eyelid thickness and intraocular pressure, prolonged preparation time, the need for additional parenteral analgesia during the surgery, as well as a decreased level of comfort for the surgeon performing the procedure.