Ultrasound Biomicroscopic Changes after Laser Iridotomy or Trabeculectomy in Angle-closure Glaucoma

Kyung-Chul Yoon; Lim-Dae Won; Hyung-Jin Cho; Kun-Jin Yang

doi:10.3341/kjo.2004.18.1.9

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Yoon, Won, Cho, and Yang: Ultrasound Biomicroscopic Changes after Laser Iridotomy or Trabeculectomy in Angle-closure Glaucoma

Original Article

Korean J Ophthalmol 2004;18(1):9-14.

Published online: 20 June 2004

DOI: https://doi.org/10.3341/kjo.2004.18.1.9

Ultrasound Biomicroscopic Changes after Laser Iridotomy or Trabeculectomy in Angle-closure Glaucoma

Kyung-Chul Yoon, MD, Lim-Dae Won, MD, Hyung-Jin Cho, MD, Kun-Jin Yang, MD

Department of Ophthalmology, Chonnam National University Hospital, Gwang-Ju, Korea

Reprint rquests to Kun Jin Yang, MD, Department of Ophthalmology, Chonnam National University Hospital, 8 Hakdong, Dongku, Gwangju 501-757, Korea.

This study was presented at the 1st meeting of the Asian Angle-closure Glaucoma Club 2002.

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This study was performed to demonstrate the ultrasound, biomicroscopic and dimensional changes of angle structure after laser iridotomy (LI) and primary trabeculectomy (PT) in primary angle-closure glaucoma (PACG). Angle-opening distance at a point 500(m from the scleral spur (AOD500), trabecular-iris angle (Θ₁), trabecular ciliary process distance (TCPD), ciliary process-iris angle (CPI), iris thickness (ID1, ID3), length of iris-lens contact distance (ILCD) and anterior chamber depth (ACD) were assessed before and after each procedure. Thirteen patients with LI and 16 with PT were prospectively enrolled. There were statistically significant increases in AOD500, Θ₁, and ILCD in both groups. CPI was decreased in both groups. ACD, TCPD, and iris thickness were not changed significantly. The changes in angle configuration after LI or PT may result more from alterations in aqueous pressure gradients across the iris and the changes of configuration were greater in the iris roots without rotation of ciliary body. However, we didn't find any significant differences in the changes of parameters between the two procedures.

Keywords: angle closure glaucoma, angle structure, laser iridotomy, trabeculectomy, ultrasound biomicroscopy

References

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Fig. 1.

Ultrasound biomicroscopic measurement positions displayed on a diagrammatic representation of the anterior segment of the eye. (A) Angle-opening distance (AOD 500) was measured on the line perpendicular to the trabecular meshwork at a point 500 µm from the scleral spur. The trabecular-iris angle (Θ₁) was measured with the apex in the iris recess and the arms of the angle passing through a point on the trabecular meshwork 500 µm from the scleral spur and through the point on the iris perpendicularly opposite. (B) Trabecular ciliary process distance (TCPD) was measured on the line extending from a point 500 µm from the scleral spur perpendicularly through the iris to the ciliary process. Iris thickness was measured 1mm from the iris root (ID1) and at its thickest point near the margins (ID3). Ciliary process-iris angle (CPI) and length of iris-lens contact distance (ILCD) are also indicated.

Table 1.

Patients demographics

	Angle-closure glaucoma patients
	Laser iridotomy group	Trabeculectomy group
Gender
(male/female, No. of patient)	2/11	3/13
Age (years)
Mean ± SD	60.30 ± 8.17	65.83 ± 5.91
(Range)	(47–70)	(59–74)

Table 2.

Mean preoperative and postoperative intraocular pressures(mmHg) in the laser iridotomy and trabeculectomy groups.

	Laser iridotomy group	Trabeculectomy group
Preoperative	42.1 ± 15.9	43.7 ± 15.6
Postoperative
2 weeks	14.8 ± 2.2	19.0 ± 2.4
2 months	15.2 ± 2.0	14.5 ± 3.2

Table 3.

Mean preoperative and postoperative ultrasound biomicroscopy (UBM) parameters in the laser iridotomy group

UBM parameter	Preoperative	Postoperative	P value
AOD^∗500(µm)	69.46 ± 25.39	187.15 ± 13.30	.000
θ₁^†(°)	11.92 ± 3.40	27.31 ± 5.23	.000
ACD^‡(µm)	1917.61 ± 281.73	2050.00 ± 251.46	.100
TPCD^§(µm)	800.23 ± 106.52	872.54 ± 105.98	.081
CPI^II(°)	26.15 ± 7.89	4.39 ± 1.22	.005
ILCD^#(µm)	605.38 ± 100.38	1053.85 ± 106.34	.000
ID^※1(µm)	545.38 ± 108.68	505.38 ± 104.61	.237
ID^※(µm)	620.77 ± 108.28	569.23 ± 89.58	.190

^∗ Angle-opening distance at a point 500(m from the scleral spur,

^† Trabecular-iris angle,

^‡ Anterior chamber depth,

^§ Trabecular ciliary process distance,

^II Ciliary process-iris angle,

^# Length of iris-lens contact distance,

^※ Iris thickness

Table 4.

Mean preoperative and postoperative ultrasound biomicroscopy (UBM) parameters in the trabeculectomy group

UBM parameter	Preoperative	Postoperative	P value
AOD^∗500(µm)	79.66 ± 31.12	230.00 ± 67.82	.004
θ₁^†(°)	9.33 ± 3.88	25.30 ± 2.07	.004
ACD^‡(µm)	2036.66 ± 406.23	2186.66 ± 416.15	.229
TPCD^§(µm)	912.50 ± 127.03	1007.83 ± 140.02	.109
CPI^II(°)	24.17 ± 7.76	11.17 ± 6.91	.020
ILCD^#(µm)	588.33 ± 67.06	980.00 ± 128.99	.004
ID^※(µm)	581.67 ± 109.26	531.67 ± 85.42	.335
ID^※(µm)	648.33 ± 95.17	598.48 ± 96.3	.199