Factors influencing laser peripheral iridotomy outcomes in white eyes: an anterior segment optical coherence...

To determine the pre-laser anterior segment optical coherence tomography (AS-OCT) features in White eyes which may predict the outcome after laser peripheral iridotomy (PI).

Consecutive White patients who underwent laser PI at Capital Eye Specialists over a 25-month period (November 2007 to November 2009) were identified, and the AS-OCT images of the temporal and nasal angles (in light and dark) before laser were analyzed. The PI was considered unsuccessful if there was still iridotrabecular apposition in the dark in ≥2 quadrants at follow up. The parameters studied were anterior chamber depth, trabecular-iris angle (TIA), angle opening distance (AOD), trabecular-iris space area, trabecular-iris contact length (TICL), iris thickness, and maximum iris bow height (MIBH).

Images of 71 eyes (71 patients) were assessed. The mean age at laser PI was 60.3 (±10.0) years. The mean time from laser PI to the follow-up AS-OCT scan was 5.92 (±3.22) weeks. The TIA 500 (P=0.002 temporal; P=0.024 nasal), AOD 500 (P=0.004 temporal; P=0.022 nasal), and TICL (P<0.001 temporal; P=0.013 nasal) in light were significantly different between the successful and unsuccessful groups. The MIBH in light was significant temporally (P=0.021) and approached significance nasally (P=0.052). Iris thickness measurements demonstrated no statistical significance.

An unsuccessful PI outcome is associated with pre-laser greater angle closure (decreased TIA 500 and AOD 500, increased TICL) and less anterior iris bowing (decreased MIBH) in light conditions in the temporal and nasal angles.