[Alteration of anterior chamber and angle structure in eyes with primary angle closure after laser peripheral iridotomy].
OBJECTIVE
To quantitatively evaluate the long-term changes in anterior segment morphology by using ultrasound biomicroscopy (UBM) after laser peripheral iridotomy (LPI) in eyes with primary angle closure (PAC).


METHODS
This was a clinical case series study. A total of 54 eyes with PAC of 31 consecutive patients were enrolled. Routine ophthalmic and UBM examination were performed at visit one (before LPI), 2 weeks, 6, and 12 months after LPI. The parameters of anterior chamber were measured by UBM and calculated. Results of each follow-up time were analyzed using repeated measures analysis of variance. Parameters of UBM measurement at 750 µm anterior to the sclera spur and at 500 µm counterpart were compared using paired student t-test.


RESULTS
Compared to before LPI, anterior chamber depth (ACD) was deepened by approximate 0.10 mm after LPI, however, it was not statistically significant (F = 3.50, P > 0.05). Angle opening distance (AOD), trabecular-iris angle (TIA), angle recess area (ARA) and trabecular-ciliary process distance (TCPD) were significantly increased at 2 weeks, 6 and 12 months after LPI compared with respective baseline [AOD750: (165.0 ± 70.3), (185.8 ± 68.5), (196.1 ± 77.7) µm vs (66.2 ± 51.6) µm, F = 92.60; TIA750: 14.1° ± 6.3°, 15.5° ± 6.2°, 16.4° ± 5.9° vs 6.4° ± 4.9°, F = 92.60; ARA: (0.058 ± 0.024), (0.065 ± 0.023), (0.068 ± 0.026) mm(2) vs (0.025 ± 0.017) mm(2), F = 92.60; TCPD: (647.1 ± 113.0), (701.8 ± 93.4), (670.1 ± 95.4) µm vs (571.0 ± 97.2) µm, F = 34.00; P < 0.05]. The parameters of UMB measurement at 750 µm were significantly increased more than that at 500 µm anterior to the sclera spur (AOD: t = 5.90, TIA750: t = 2.70, P < 0.05; ARA: t = 2.00, P = 0.05).


CONCLUSIONS
LPI can significantly widen the peripheral anterior angle in eyes with PAC lasting for at least 1 year after LPI. Parameters detected by UBM at 750 µm anterior to the sclera spur appear to be more sensitive in evaluating the alternation of peripheral angle structure.
Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China.
Zhong
Z
Lin
Si-zhen
SZ
Li
Su-jie
SJ
Fan
Da-peng
DP
Mu
Ning-li
NL
Wang
Xia
X
Sun
Wen-ru
WR
Liu
Xin
X
Tang
Lan-ping
LP
Sun
Yuan-bo
YB
Liang
D000368:Aged; D000369:Aged, 80 and over; D000867:Anterior Chamber / Q000000981:diagnostic imaging*; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D032801:Iridectomy / Q000379:methods*; D007498:Iris / Q000000981:diagnostic imaging; D053685:Laser Therapy; D008297:Male; D033401:Microscopy, Acoustic; D008875:Middle Aged