Ultrasound Biomicroscopy Evaluation Of Changes In Anterior Segment After Laser Peripheral Iridotomy And The Correlations Between Ultrasound Biomicroscopy And Anterior Segment Optical Coherence Tomography

PURPOSE：1. Use ultrasound biomicroscopy (UBM) to evaluate thechanges of anterior segment morphology before and after laser peripheraliridotomy (LPI).2. Using anterior segment optical coherence tomography(AS-OCT) to quantitatively assess anterior segment parameters ofprimary angle closure glaucoma (PACG) and primary angle closure(PAC), and to evaluate the correlations between parameters of UBM andAS-OCT, providing reference to clinical applications.METHODS：This is a retrospective study.55eyes of34patientswho visited Opthalmology department of Shanghai sixth hospital in2013were enrolled. They were examined systematically and diagnosed PACGremission (11eyes of8subjects), early PACG (20eyes of20subjects)and PAC (24eyes of12subjects).1. UBM examinations were performedbefore and after LPI. Under light condition, the superior, inferior, nasaland temporal quadrants of each eye were examined. Main outcome parameters were central anterior chamber depth (cACD), angle openingdistance at250and500μm from scleral spur (AOD250and AOD500),trabecular iris angle (TIA), and angle recess area(ARA).2. Parameters ofAS-OCT measurement at750μm anterior to the sclera spur and at500μm counterpart were examined after LPI. The light condition andquadrants of examination were the same as those of UBM. Main outcomemeasurements were anterior chamber angle(ACA), trabecular iris angle(TIA), angle opening distance at500and750μm from scleral spur(AOD500and AOD750), and trabecular iris space area(TISA). Thecorrelation and variability of two groups (AOD500and AOD750) wereevaluated.3. To evaluate the correlations of selected parameters(AOD500and TIA) between UBM and AS-OCT. All parameters wereanalyzed by SPSS16.0and MedCalc.RESULTS:1.The curve of iris was flatter after LPI. cACD, AOD,TIA and ARA were significantly increased after LPI(P＜0.05).2. Anteriorchamber angle parameters of ACA, TIA, TISA and AOD measured byAS-OCT reached the maximum at temporal quadrant and minimum atsuperior quadrant. Group parameters of AOD500and AOD750showedlinear positive correlation, and group of AOD750had less variability.3.UBM outcomes of AOD500and TIA were smaller than those ofAS-OCT(P＜0.01). The results of two equipments were correlated atsuperior, nasal and inferior quadrants. Two equipments might be alternatives to each other.CONCLUSION:1. UBM could be used to detect early stage ofprimary angle closure glaucoma and efficient tool of follow up during thecourse of this disease. LPI could deepen anterior chamber depth, widenanterior chamber angle and flatten the iris. LPI could prevent PACG fromacute attack for short period.2. AS-OCT presented some different resultsfrom UBM in the measurement of TIA and AOD500, but it was notclinically significant. AS-OCT is better than UBM in detection ofconstrictive space between peripheral cornea and iris root.3. AS-OCTwas a kind of non-contact equipment with high resolution and wasuser-friendly. Parameters detected by AS-OCT at750μm anterior to thesclera spur appear to be fewer variables than those at500μm and valuableclinically. We recommend using parameters at750μm anterior to thesclera spur to do the screening and follow up of PACG and PAC.