Predicting the Therapeutic Efficacy of Laser Peripheral Iridotomy for Individuals With Asymptomatic Narrow Angle: The Triple Hump Sign

Abstract

Purpose: To evaluate the clinical efficacy of a novel screening sign [ie, the triple hump (TH) sign] for prediction of laser peripheral iridotomy (LPI)'s intraocular pressure (IOP)-lowering effectiveness in subjects with asymptomatic narrow angles.

Methods: This cross-sectional study was conducted from 2010 to 2015 in a hospital setting. Eighty-four eyes of 84 primary angle-closure suspect (PACS) patients were imaged before LPI using anterior segment optical coherence tomography. The "positive-TH sign" was defined, on anterior segment optical coherence tomography-generated cross-sectional scans, as the characteristic configuration formed by the angulations between the crystalline lens's central anterior surface and both sides of the iris pigment epithelium. After LPI, the extent of IOP reduction was compared between the positive- and negative-TH groups.

Results: The positive-TH eyes did not significantly differ from the negative-TH ones in pre-LPI IOP (P = 0.200). In the positive-TH group, IOP decreased significantly after LPI (by 6.42% +/- 17.96%, from 14.07 +/- 3.11 to 12.88 +/- 2.65 mm Hg, P = 0.002). In the negative-TH group, IOP did not change significantly after LPI (by 4.66% +/- 25.97%, from 13.23 +/- 2.42 to 13.52 +/- 3.01 mm Hg, P = 0.624).

Conclusion: PACS eyes indicating the positive-TH sign showed, at post-LPI 1 month, a greater IOP decrease. On this basis, the TH sign may be a useful screening tool for predicting the effect of LPI and determining the treatment plan in PACS patients.