Abstract
Purpose :
Plateau iris syndrome (PIS) and plateau iris configuration (PIC) are classically defined by a narrow angle and a double-hump configuration on gonioscopic examination. In PIC, a relative pupil block mechanism may be present and iridotomy is sometimes effective. Ultrasound biomicroscopy (UBM) is a helpful ancillary exam in PIC/PIS workup. Our aim was to investigate if we can predict, using UBM, the response of a PIC/PIS to an iridotomy.
Methods :
Prospective observational study. A double-hump on gonioscopy was identified in all eyes and the patients were scheduled for an iridotomy. UBM was performed before and after iridotomy by the same masked observer. Further analysis of stored UBM images was performed by a second masked observed and included evaluation of qualitative and quantitative data concerning iridocorneal angle anatomy, anterior chamber parameters and lens characteristics. Only high-quality images were accepted and STATA v13.0 was used for statistics.
Results :
From Feb-Set/15, 22 eyes of 13 Caucasian patients (8 women) were enrolled. In 7 (31.8%) eyes, a patent iridotomy resulted in angle opening. Mean anterior chamber depth before and after iridotomy was 2.58±0.4mm and 2.54±0.3mm (p=0.30), respectively. Lens vault (LV) was 0.54±0.1mm and lens lenght (LL) 4.10±0.3mm. Mean LL/LV ration was 8.17±2.1. In a logistic regression model, LL/LV ratio was significantly associated with angle opening after iridotomy (odds ratio, 1.86; 95% confidence interval 1.03 to 3.30). Iridotomy was not effective in eyes with a LL/LV ratio below 6,9.
Conclusions :
To conclude about a definitive PIS diagnosis it is mandatory to analyze the angle after an iridotomy. Although not yet clarified as useful in plateau iris patients, lens characteristics may contribute in some degree to pupil block. In our sample, LL/LV ratio seems to be a helpful predictor of iridotomy effectiveness in the presence of a clinical plateau iris. This work may trigger further studies about this potential quantitative and easily measurable clinical index in PIC/PIS field.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.