Bleb Morphology of Fornix-Based Versus Limbus-Based Conjunctival Flaps in Trabeculectomy with Mitomycin C

Byeong Hee Lee; Won Suk Choi; Jong Wook Lee; Kyoo Won Lee

doi:10.3341/jkos.2011.52.12.1461

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Lee, Choi, Lee, and Lee: Bleb Morphology of Fornix-Based Versus Limbus-Based Conjunctival Flaps in Trabeculectomy with Mitomycin C

Original Article

J Korean Ophthalmol Soc 2011;52(12):1461-1469.

Published online: 7 September 2011

DOI: https://doi.org/10.3341/jkos.2011.52.12.1461

Bleb Morphology of Fornix-Based Versus Limbus-Based Conjunctival Flaps in Trabeculectomy with Mitomycin C

Byeong Hee Lee, MD, Won Suk Choi, MD, Jong Wook Lee, MD, Kyoo Won Lee, MD

Cheil Eye Hospital, Daegu, Korea

Address reprint requests to Kyoo Won Lee, MD Cheil Eye Hospital #803-2 Sinam-dong, Dong-gu, Daegu 701-011, Korea Tel: 82-53-959-1751, Fax: 82-53-959-1758, E-mail: eye7575@korea.com

Received 25 October 201123 May 2011 Accepted 5 November 2011

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

Purpose

To compare the bleb morphology and surgical outcomes of a limbus-based group with those of a fornix-based group who underwent trabeculectomy with mitomycin C (MMC).

Methods

Sixty-five eyes of 59 patients who had undergone trabeculectomy with MMC and who were observed for one year or more were included in the present study. A limbus-based conjunctival flap was used for 34 eyes of 31 patients and a fornix-based conjunctival flap for the other 31 eyes of 28 patients. The bleb morphologies were classified and compared after one year or more postoperatively according to the Moorfield Bleb Grading System, and intraocular pressure and success rates were evaluated.

Results

The central bleb vascularity of the limbus-based group was statistically significantly lower than that of the for-nix-based group (1.79 ± 0.64; 2.16 ± 0.73, p = 0.042). The risk of cystic bleb formation was higher in the limbus-based group (38.2%; 16.5%, p = 0.047). There were no differences in the IOP or success rate between the two groups.

Conclusions

There were no differences between the two groups with regard to the IOP or cumulative success rate. However, in the fornix-based group, the central bleb vascularity was lower and the risk of avascular cystic bleb formation was higher than those in the limbus-based group.

Keywords: Bleb morphology, Trabeculectomy

References

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Figure 1.

Standard photographs of Moorfields bleb grading system.

Figure 2.

Morphology of conjunctival blebs following limbus-based group.

Figure 3.

Morphology of conjunctival blebs following fornix-based group.

Figure 4.

Postoperative cumulative success rates of the two surgical groups (Kaplan-Meier survival curve). A blue line is fornix-based group and a green line is limbus-based group. Left graph: group without medication, there is no significant difference (p = 0.073, Log rank test). Right graph: group with medication, There is also no significant difference (p = 0.686, Log rank test).

Table 1.

Preoperative characteristics of the two surgical groups

	Limbus-based group	Fornix-based group	p-value
Number of patients (eye)	31 (34)	28 (31)
Sex (M/F)	20/11	19/9	0.787^∗
Age (mean ± SD, yr)	59.2 ± 12.0	59.2 ± 15.9	0.990^†
Previous filtering surgery	3	1	0.615^‡
Other previous intraocular surgery	6	10	0.172^∗
Glaucoma type
POAG	21	21
CACG	7	4
Secondary glaucoma	5	3
Neovascular glaucoma	1	2
PXG	0	1
Preoperative intraocular pressure (mean ± SD, mm Hg)	28.1 ± 7.5	28.8 ± 7.7	0.687^†
Duration of followup (mean ± SD, mon)	21.0 ± 4.4	20.8 ± 4.5	0.862^†

POAG = primary openangle glaucoma; CACG = chronic angle-closure glaucoma; PXG = pseudoexfoliative glaucoma.

^∗ Chi-square test

^† Student's t-test

^‡ Fisher exact test.

Table 2.

Comparision of bleb morphology between the two surgical groups after 1 year of followup

Group	Bleb area 1a	Bleb area 1b	Bleb height	Vascularity 3a	Vascularity 3b	Vascularity 3c
Limbus-based	1.85 ± 0.61	2.47 ± 0.71	1.66 ± 0.66	1.79 ± 0.64	2.29 ± 0.80	2.76 ± 0.82
Fornix-based	2.00 ± 0.52	2.55 ± 0.62	1.87 ± 0.67	2.16 ± 0.73	2.42 ± 0.72	2.65 ± 0.75
p-value^∗	0.282	0.726	0.214	0.042	0.505	0.577

Values are presented as mean ± SD.

1a = the central demarcated area of the bleb; 1b = the maximal area of the bleb; 3a = the vascularity of the central bleb; 3b = the vascularity of the peripheral bleb; 3c = the vascularity of the peripheral non-bleb-related conjunctiva.

^∗ Mann-Whitney U test.

Table 3.

Preoperative and postoperative intraocular pressure (mm Hg) after trabeculectomy with mitomycin C

	Limbus-based group	Number of eyes examined	Fornix-based group	Number of eyes examined	p-value^∗
Preoperative	28.1 ± 7.5	34	28.8 ± 7.7	31	0.687
Postoperative
1 month	13.3 ± 4.2	34	11.9 ± 3.9	31	0.219
6 months	11.7 ± 3.3	34	11.0 ± 2.8	31	0.419
12 months	11.6 ± 3.0	34	10.3 ± 2.8	31	0.154
18 months	12.4 ± 3.5	28	11.7 ± 3.6	25	0.616
24 months	12.0 ± 3.0	23	11.7 ± 2.5	19	0.738

Values are presented as mean ± SD or number.

^∗ Student's t-test.

Table 4.

Postoperative success rates of the two surgical groups

	Limbus-based group	Fornix-based group	p-value^∗
Success rate without medication
6 months	19/34 (55.9)	22/31 (71.0)	0.208
12 months	18/34 (52.9)	21/31 (67.7)	0.224
18 momths	15/28 (53.6)	17/25 (68.0)	0.284
24 months	12/23 (52.2)	12/19 (63.2)	0.474
Success rate with medication
6 months	30/34 (88.2)	28/31 (90.3)	0.786
12 months	30/34 (88.2)	27/31 (87.1)	0.889
18 months	24/28 (85.7)	22/25 (88.0)	0.806
24 months	19/23 (82.6)	16/19 (84.2)	0.890

Values are presented as number (%).

^∗ Chi-square test.

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