A prospective ultrasound biomicroscopy evaluation of changes in anterior segment morphology after laser iridotomy in asian eyes

• Published in: Ophthalmology (Rochester, Minn.) Vol. 110; no. 3; pp. 630 - 638
• Main Authors: Gazzard, Gus, Friedman, David S, Devereux, Joe G, Chew, Paul, Seah, Steve K.L
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.03.2003; Elsevier
• Subjects: Acute Disease; Adult; Aged; Aged, 80 and over; Anterior Eye Segment - diagnostic imaging; Biological and medical sciences; Female; Glaucoma, Angle-Closure - diagnostic imaging; Glaucoma, Angle-Closure - ethnology; Glaucoma, Angle-Closure - surgery; Gonioscopy; Humans; Iridectomy - methods; Iris - diagnostic imaging; Iris - surgery; Laser Therapy; Male; Medical sciences; Middle Aged; Prospective Studies; Singapore - epidemiology; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Surgery of the eye and orbit; Ultrasonography; Biomicroscopy; Human; Evaluation; Change; Anterior segment; Eye; Prospective; Surgery; Morphology; Laser; Ophthalmology; Iridotomy; Ultrasound
• ISSN: 0161-6420; 1549-4713
• DOI: 10.1016/S0161-6420(02)01893-6

To prospectively quantify changes in anterior segment morphology after laser iridotomy using gonioscopy and ultrasound biomicroscopy (UBM). Prospective comparative observational case series. Fifty-five fellow eyes of patients presenting with acute primary angle closure (APAC). The fellow eyes of patients presenting with APAC were examined with UBM, A-scan ultrasonography, and optical pachymetry at presentation and 2 weeks after sequential argon/neodymium yttrium–aluminum–garnet laser peripheral iridotomy (LPI). UBM images were analyzed using UBM Pro 2000 software. Baseline measurements were made both under standard lighting conditions and in darkness to look for changes in anterior segment findings. The degree of angle opening was measured using the angle-opening distance (AOD) at 250 and 500 μm from the scleral spur (AOD250 and AOD500, respectively) and angle recess area (ARA). Fifty-five Asian patients were examined; AOD250, AOD500, and ARA all significantly increased after sequential laser iridotomy ( P < 0.002). Gonioscopic grading of the angle opening significantly increased in all 4 quadrants ( P < 0.001). The Van Herick grade of limbal anterior chamber depth increased ( P < 0.001), whereas the number of eyes classified as occludable decreased (73%–33%, P < 0.001). Anterior chamber depth did not change significantly (2.41 mm ± 0.28 mm vs. 2.42 mm ± 0.30 mm, P = 0.43) as measured with optical pachymetry. Increased illumination increased the angle-opening measures, but induced a different alteration in peripheral iris morphology. Illumination-induced changes were greater after iridotomy than before laser treatment. In Asian eyes at high risk of developing APAC, sequential LPI produced a significant widening of the anterior chamber angle without deepening the anterior chamber centrally. LPI produces changes in iris morphology that are different from those caused by an increase in illumination, indicating that different mechanisms account for angle opening under these 2 conditions.