Size Matters for Interplicata Diameter: A Case-Control Study of Plateau Iris

Area of Science:

• Ophthalmology
• Anterior Segment Imaging
• Glaucoma Research

Background:

• Ultrasound biomicroscopy (UBM) is utilized for anterior segment analysis.
• Characterization of anterior segment dimensions in plateau iris configuration (PIC) is established.
• Transverse measurements like sulcus-to-sulcus diameter (STSD) and interplicata diameter (IPD) in PIC have not been previously reported.

Purpose of the Study:

• To measure STSD and IPD using UBM.
• To compare STSD and IPD between eyes with PIC, primary angle closure (PAC), and open-angle controls.
• To investigate potential differences in anterior segment dimensions associated with angle closure.

Main Methods:

• A retrospective, cross-sectional study involving 69 participants (37 PIC, 13 PAC, 19 controls).
• Anterior segment measurements including STSD and IPD were performed using UBM.
• Statistical analysis using ANOVA and t tests identified significant differences among the groups.

Main Results:

• Eyes with PAC had a smaller anterior chamber depth (ACD) than PIC and control eyes.
• Angle opening distance (AOD) was smaller in PIC and PAC eyes compared to controls.
• Both vertical and horizontal STSD and IPD were significantly smaller in PIC and PAC eyes compared to control eyes.

Conclusions:

• STSD and IPD are reduced in eyes with PIC and PAC compared to healthy eyes.
• These findings suggest anatomical differences in the anterior segment of eyes predisposed to angle closure.
• Further research into the ratio of white-to-white cornea diameter to IPD may elucidate mechanisms for conditions like uveitis-glaucoma-hyphema syndrome in PIC.