According to the study of Gramer et al., congenital glaucoma is rare in aniridia patients, and the onset of glaucoma occurs in adolescence and early adulthood most [
13]. Therefore, the monitoring of glaucoma should have been sustained since the diagnosis of aniridia. Surgery is often necessary to treat aniridic glaucoma. Different advocations about the methods of surgery reveal the refractoriness of aniridic glaucoma.
Various surgical procedures, including goniosurgeries, trabeculectomy, glaucoma drainage implants and cyclodestructive procedures, have been reported in previous researches. Goniosurgeries, including goniotomy and trabeculotomy, are the most reported approaches. The success rate of goniotomy varied in previous studies depending on the timing of intervention. Prophylactic goniotomy showed far better prognosis compared with therapeutic one [
1]. Adachi et al. summarized 12 aniridic glaucoma eyes receiving trabeculotomy, and the results showed that 10 eyes received good IOP control with an average follow-up of 9.5 years. Thus, they suggested that trabeculotomy should be adopted as an initial method [
12]. On the contrary, trabeculectomy demonstrates limited success rate. The study of Durai et al. revealed that the cumulative probability of failure was 58.3% in the trabeculectomy group at 2 years [
14], and Wiggins et al. reported a success rate of only 7% receiving trabeculectomy [
15]. Glaucoma drainage implant is another option. Almousa et al. implanted the Ahmed glaucoma valve for 8 aniridic glaucoma eyes, and 7 eyes received good IOP control [
16]. Wiggins et al. also reported successful outcomes of glaucoma drainage implant in advanced patients who had already received prior glaucoma surgeries [
15]. Although the efficacy of IOP control is good, complications related to implants, e.g., tube exposure, tube obstruction and corneal endothelial damage, may still occur in a high incidence [
15‐
17]. Therefore, it may be better to preserve glaucoma drainage implants as a remedial procedure. Though cyclodestructive procedures are effective in controlling IOP, they often cause serious complications including hypopsia, cataract, retinal detachment and phthisis bulbi [
15,
18,
19]. It may be unsuitable to select cyclodestructive surgery as an initial surgical choice to treat aniridic glaucoma patients who remain poor vision. The clinical information of prior studies is demonstrated in Table
1. In summary, prophylactic goniotomy provides good outcome in patients whose angle is open in early stage. However, surgical interventions demonstrate either limited efficacy or high incidence of postoperative complications in advanced patients. A new surgical approach is needed urgently for aniridic glaucoma patients following failed previous surgery.
Table 1
Summary of previous studies and current study on aniridic glaucoma patients treated with various surgical procedures
Prophylactic goniotomy | | 55 | 3.1 | IOP < 22mmHg w/o medications | 9.5 [range, 0.7 ~ 24] | 89.1 | Not observed |
Therapeutic goniotomy | | 14 | 7 | IOP ≤ 21mmHg w/ or w/o medications | 3.8 [range, 0 ~ 11]a | 21.4 | Not observed |
Trabeculotomy | Adachi et al. (1997) [ 12] | 12 | 4.7 | IOP ≤ 21mmHg w/ or w/o medications and no further glaucoma surgery | 11.6 [range, 4 ~ 23] | 83.3 | Hyphema (8.3%) and transient IOP rise (8.3%) |
Trabeculectomy | | 12 | 17.2 | 5mmHg < IOP ≤ 21mmHg or reduced ≥ 20% from baseline on 2 consecutive follow-up after 3 months, w/o glaucoma reoperation, complications and loss of light perception | 3.6 [range, 2 ~ 4] | 41.7 (at 2-year follow-up)b | Superior ciliary staphyloma (8.3%), retinal detachment (8.3%) and cataract (41.7%) |
| Wiggins et al. (1992) [ 15] | 15 | N/Ac | IOP ≤ 21mmHg w/ or w/o medications and no complications resulting in significant visual loss | N/Ac | 6.7 | Retinal detachment (6.7%) |
Glaucoma drainage implants | Almousa et al. (2013) [ 16] | 8 | 49 | 5mmHg < IOP < 22mmHg w/ or w/o medications, w/o loss of light perception and no further glaucoma surgery | 3.1 [range, 2.6 ~ 5.7] | 87.5 | Hyphema (12.5%), Persistent vitreous hemorrhage (12.5%), retinal detachment (12.5%) and phthisis bulbi (12.5%) |
| Wiggins et al. (1992) [ 15] | 6 | N/Ac | IOP ≤ 21mmHg w/ or w/o medications and no complications resulting in significant visual loss | N/Ac | 83.3 | Tube migration (16.7%) |
Cyclodestructive procedures | | 8 | N/Ac | IOP ≤ 21mmHg w/o devastating complications or need for further glaucoma surgery | N/Ac | 25 | Phthisis bulbi (50%) and retinal detachment (12.5%) |
| Wallace et al. (1998) [ 19] | 9 | 4.8 | IOP ≤ 25mmHg w/ medications or better | 11.9 [range, 4.5 ~ 17.9] | 66.7 | Cataract (77.8%) |
| Wiggins et al. (1992) [ 15] | 22 | N/Ac | IOP ≤ 21mmHg w/ or w/o medications and no complications resulting in significant visual loss | N/Ac | 22.7 | Phthisis bulbi (9.1%) and progressive cataract (4.5%) |
Illuminated microcatheter-assisted circumferential trabeculotomy | This case report | 1 | 21 | IOP ≤ 25mmHg w/ or w/o medications | 1 | N/A | Not observed |
To the best of our knowledge, this case is unique in its first use of MAT for treating aniridic glaucoma. Our patient received goniotomy previously, but failed to control the IOP after 3 years. The result is in accordance with previous reports [
1,
7]. We attempt to figure out a better approach with higher success rate and fewer complications. Adachi et al. advocated that abnormality of Schlemm canal, which was similar to congenital glaucoma, was a mechanism of aniridic glaucoma [
12]. In several recent literatures, MAT showed satisfied results in patients with congenital glaucoma, and many of these cases possessed cloudy corneas. In these researches, the criteria of success were defined as IOP ≤ 21 mm Hg with or without antiglaucoma medications. The success rate reached 88% and no severe complications were observed [
9,
21,
22]. Therefore, these researches provide theoretical basis for us to use MAT to treat aniridic glaucoma. The advantage of circumferential trabeculotomy is the ability to maximize the IOP-reducing effect by treating the whole anterior chamber angle in a single surgery. The illuminated catheter tip also enables us to see the location directly across the sclera without the need of direct gonioscopy which may need a certain extent of corneal clarity. The postoperative IOP remains stable generally with topical medications within 1 year in our patient. The application of MAT in the treatment of aniridic glaucoma may be regarded as qualified successful. Compared with goniotomy which shows higher success rate in younger patients who have not developed glaucoma yet, MAT may be a potential option for treating aniridic glaucoma patient who is older and has experienced a previously failed surgery.