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M. Kirzhner, Y. Shildkrot, G. J. Gladstone, E. H. Black; Effect of Topical Anesthetic on Bell's Phenomenon. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5285.
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To determine the effect of corneal anesthetic application on Bell's phenomenon measurement.
This was a clinic based, randomized, prospective cross-sectional study approved by the Institutional Review Board of Wayne State University. Appropriate consent and HIPAA disclosures were made. Bell’s phenomenon (BP) was evaluated before and after instillation of one drop of proparacaine hydrochloride ophthalmic solution USP, 0.5%. Adequate anesthesia was assessed by subjective cessation of burning following administration. A novel grading system was established to quantify BP from -4 to +4 depending on the direction of eye movement and amount of corneal show after forceful elevation of the upper eyelid. Measurements of visual acuity, levator function, extraocular movement, lagophthalmos, and margin-to-reflex-distance-one (MRD1) were obtained as well. Patients with previous eyelid or extraocular muscle surgery, radiation to head or neck, history of infiltrative, inflammatory, infectious, or traumatic conditions involving the eyes and periocular tissues were excluded.
44 eyes of 44 patients (24 male, 20 female) were randomized to enter the study. For patients with unilateral corneal pathology, only the normal eye was enrolled. Mean patient age was 53.4 ± 17.1 years. There was a statistically significant decrease in BP from 2.65 ± 1.39 to 1.83 ± 1.63 following proparacaine use (p = 0.00017, 2 tailed t-test). No statistically significant difference in Bell's phenomenon was observed between Caucasian and African American study participants (p = 0.219, 2-tailed t-test) or between males and females (p = 0.892, 2-tailed t-test).
Bell’s phenomenon was found to be decreased by administration of topical anesthesia. Therefore, when used for preoperative evaluation of a ptosis patient, BP has to be performed before application of any anesthetic drops for most accurate surgical planning. Findings of our study further suggest that it is the decrease in corneal sensation that weakens this protective mechanism. This has important implications for evaluation and documentation of Bell’s phenomenon in patients susceptible to long-standing corneal hypoesthesia, including diabetic patients and patients following corneal transplantation. Further studies are necessary in establishing the importance of decreased Bell’s phenomenon in these patient populations.
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