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The following is a summary of “Does blepharospasm effect biometric parameters and intraocular lens power calculations?,” published in the August 2024 issue of Ophthalmology by Basol et al.
Benign essential blepharospasm (BEB) and hemifacial spasm (HFS) can impact eye health. Botulinum toxin-A (BTX-A) is often used for treatment. However, the effects of this treatment on eye shape and measurements still need to be fully understood.
Researchers conducted a retrospective study to analyze how BTX-A treatment affects corneal topography, ocular biometry, and keratometry in patients with BEB and HFS.
They studied 66 eyes from 33 patients with BEB and 5 eyes from 5 patients with HFS, all treated with BTX-A. The refractive errors, tear break-up time (TBUT), corneal topography [corneal power of flat axis (K1) and steep axis (K2), mean corneal power (Km), corneal astigmatism (K2-K1)], ocular biometry [axial length (AL), anterior chamber depth (ACD)], and expected emmetropic intraocular lens power (emm-IOL) before treatment and 1 month after were recorded, using SRK-T, Holladay, Hoffer-Q, and Haigis formulas.
The results showed that K1 (43.48 ± 2.02 vs. 43.57 ± 2.08, P= 0.036), Km (43.91 ± 1.99 vs. 43.99 ± 2.06, P=0.024), and ACD (3.22 (2.77–3.76) vs. 3.41 (2.99–4.02), P<0.001) were significantly higher. Expected emm-IOL by SRK-T (21.04 ± 1.6 vs. 20.93 ± 1.6, P=0.048), Holladay (21.05 ± 1.6 vs. 20.91 ± 1.62, P=0.037), and Hoffer-Q (21.08 ± 1.65 vs. 20.94 ± 1.68, P=0.038) decreased significantly. Haigis formula change was not significant (P=0.386). TBUT was significantly lower (P<0.001), with other parameters showing no significant change (P>0.05).
Investigators concluded the first study to compare optic biometry and IOL power formulas before and after BTX-A in BEB and HFS, and BTX-A can affect keratometric and ACD values, so repeated measurements post-injection are recommended for accuracy.
Source: link.springer.com/article/10.1007/s10792-024-03277-5
