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  • Effects of Pupillary Dilation in PAC Suspects With Cataract

    By Lynda Seminara
    Selected By: Stephen D. McLeod, MD
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    Journal Highlights

    Ophthalmology, January 2021

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    Anatomic changes caused by visually significant cataract (VSC) may predis­pose patients with primary angle-closure (PAC) to rises in intraocular pressure (IOP) and acute angle closure during pupillary dilation. Safety studies of pharmacologic dilation in this population are lacking, as is research on dynamic changes in IOP and anterior chamber structures beyond one hour after cataract surgery. To fill the void, Zhao et al. looked at these parameters with swept-source optical coherence tomography (SS-OCT) in PAC suspects admitted for cataract surgery. They found no cases of acute PAC and a low risk of IOP elevation.

    This prospective study was conduct­ed at Shanghai General Hospital. PAC suspects with VSC and no prior laser or intraocular surgery underwent a standardized eye exam, biometry, and SS-OCT before pupillary dilation with 0.5% tropicamide and 0.5% phenyleph­rine hydrochloride. IOP measurements and SS-OCT were repeated at one, four, and six hours after dilation (PDH1, PDH4, and PDH6, respectively). Main outcome measures were changes in IOP and SS-OCT parameters.

    The study included 78 patients (78 eyes); mean age was 71 years, and 74% were female. Most patients completed the PDH1 and PHD4 assessments (100% and 85%, respectively). The mean IOP increased from 14.8 ± 2.6 mm Hg at baseline to 15.5 ± 3.5 mm Hg at PDH1 (p = .03) but fell to 14.9 ± 3.1 mm Hg by PDH4 (p = .09). The IOP increase was ≥5 mm Hg at PDH1 and PDH4 in four patients (5.13%) and three patients (3.85%), respectively, and was ≥8 mm Hg in two patients (2.56%) and one patient (1.28%), respectively. By PDH6, no patient’s IOP was elevated ≥5 mm Hg. No episodes of acute PAC were reported during the ob­servation period. Lens vault and iris volume declined from baseline to PDH1 and were sustained to PDH4. Other SS-OCT measure­ments were found to be significantly increased at both assessments. At PDH1, the only factor that was negatively linked to IOP elevation level was increased anterior chamber depth (p = .003).

    According to the authors, the low risk for IOP spike in this cohort may relate to relaxation of the ciliary mus­cle, leading to posterior displacement of the lens-iris diaphragm and deep­ening of the anterior chamber. They urged further study of anterior chamber structures to elucidate the mechanism of dilation-related IOP changes in PAC suspects and to identify related risk factors.

    The original article can be found here.