Menoufia Medical Journal

ORIGINAL ARTICLE
Year
: 2020  |  Volume : 33  |  Issue : 2  |  Page : 653--658

Comparison between Ahmed glaucoma valve and diode laser cyclophotocoagulation in the management of refractory glaucoma


Hany A Khairy1, Moataz F El-Sawy1, Asmaa A El-Enany2,  
1 Department of Ophthalmology, Faculty of Medicine, Menoufia University, Menoufia, Egypt
2 Department of Ophthalmology, Shebin El-Kom OphthalmologyHospital, Menoufia, Egypt

Correspondence Address:
Asmaa A El-Enany
Shebin El-Kom, Menoufia
Egypt

Abstract

Objective The aim of the study is to compare between Ahmed glaucoma valve (AGV) and cyclodiode laser photocoagulation in the management of refractory glaucoma. Background To compare the intraocular pressure (IOP) reduction and safety of diode laser contact cyclophotocoagulation (DCPC) and AGV in cases of refractory glaucoma. Patients and methods This study was a prospective, consecutive trial. Patients were recruited from the Eye Outpatient Department at Menoufia University Hospital, Egypt. The study was conducted on 20 eyes of 20 patients. Patients were divided into two groups, with 10 patients each. All patients underwent a baseline complete ophthalmologic examination and IOP measurement before and after 1, 3, and 6 months of follow-up. Complications were recorded. Group I underwent AGV surgery and group II underwent DCPC. Results There was no significant difference among group I and group II regarding age, sex, and preoperative IOP. The mean postoperative IOP after 1 month for group I was 14.80 ± 4.10 and was 25.0 ± 6.68 for group II, with a significant difference (P = 0.004). The mean postoperative IOP after 6 months for group I was 19.10 ± 5.74 and was 20.0 ± 7.44 for group II, with no significant difference (P = 0.436). In patients with AGV, the most frequent complication was hyphema. In patients with DCPC, eye pain was the most frequently observed complaint. Conclusion Greater IOP reduction was achieved by AGV, but the difference between it and cyclodiode laser was not significant. AGV had more serious complications.



How to cite this article:
Khairy HA, El-Sawy MF, El-Enany AA. Comparison between Ahmed glaucoma valve and diode laser cyclophotocoagulation in the management of refractory glaucoma.Menoufia Med J 2020;33:653-658


How to cite this URL:
Khairy HA, El-Sawy MF, El-Enany AA. Comparison between Ahmed glaucoma valve and diode laser cyclophotocoagulation in the management of refractory glaucoma. Menoufia Med J [serial online] 2020 [cited 2020 Aug 11 ];33:653-658
Available from: http://www.mmj.eg.net/text.asp?2020/33/2/653/287797


Full Text



 Introduction



Glaucoma is a multifactorial optic neuropathy characterized by loss of the retinal ganglion cells axons, leading to progressive irreversible loss of vision, manifested by cupping and atrophy of the optic disc. Such loss develops retinal nerve fiber layer thinning and characteristic visual field abnormalities. The mechanism of axonal loss is unknown, but studies have established relationship between chronic elevated intraocular pressure (IOP) and remodeling of the optic nerve head tissue, known clinically as cupping of the optic disc[1].

Although many risk factors have been described for glaucoma development and progression, lowering IOP is the only scientifically demonstrated method to slow the progression of the disease[2].

There are various therapeutic options for treating glaucoma, including antiglaucoma medication, laser, and surgery[3].

Refractory glaucoma is defined as uncontrolled IOP with evidence of optic nerve and/or visual field deterioration despite maximally tolerated antiglaucoma medications (topical and/or systemic), previously failed nonseton surgical treatment, or a combination of surgery and medicines or a high risk of failure of trabeculectomy[4].

Various surgical techniques have been proposed for treatment of refractory glaucoma such as mitomycin C, augmented trabeculectomy, and the use of glaucoma drainage devices[5].

Trabeculectomy remains the gold standard surgical procedure for most glaucoma cases worldwide since it was first introduced[6].

Although this procedure is very effective in reducing IOP in the short term, surgical failure has often been observed over time[7].

Aqueous shunts are a reliable alternative to trabeculectomy[8].

Conceptually, shunting aqueous humor to the posterior subconjunctival space may avoid healing issues, especially in patients who have already undergone previous glaucoma surgeries or conjunctival manipulation.

The first successful prototype of aqueous shunt was the Molteno implant, followed by Krupin, Ahmed, and Baerveldt implant[9].

Ahmed glaucoma valve (AGV) implantation is a glaucoma drainage device[10].

The implant was equipped with a valve to reduce the occurrence of hypotony and its related complications following the early postoperative period[11].

An alternative approach to lower IOP is to reduce aqueous production from the ciliary body. This was originally carried out using cryotherapy. However, more recently contact and noncontact transscleral cyclophotocoagulation has been popularized, initially with ND:YAG laser (cyclo-YAG) and more recently with diode laser (cyclodiode).

The use of the diode laser has the theoretical advantage of good penetration and absorption by the tissues of the ciliary body[12].

The aim of present study is to compare IOP reduction and safety of diode laser cyclophotocoagulation (DCPC) and AGV in cases of refractory glaucoma.

 Patients and Methods



This study was a prospective, consecutive trial. Patients were recruited from the Eye Outpatient Department at Menoufia University Hospital, Egypt. It was done between March 2018 and March 2019.

The study protocol was approved by the Ethical Committee of Menoufia Medical School. The study protocol was explained to the patients, and all patients provided a written informed consent. Ahmed valve surgery and diode laser were performed by Dr Hany A. Khairy.

Eligible patients included were those with refractory glaucoma.

Diagnostic criteria of refractory glaucoma were as follows: eyes with glaucoma that are uncontrolled by maximally tolerated medical therapy and that meet at least one of the following criteria: failed one or more incisional intraocular glaucoma surgeries (e.g., glaucoma filtering surgery or tube shunt), failed one or more cilioablative procedures (e.g., cyclodiode therapy), had neovascular glaucoma, or had any other condition (e.g., conjunctival scarring, uveitis) in which a conventional incisional glaucoma surgery like trabeculectomy would be more likely to fail than for an eye with uncomplicated primary open-angle glaucoma.

Criteria for inclusion in the study were all ages included, average baseline IOP more than 22 mmHg, while on maximally tolerated medical treatment.

Exclusion criteria were visual acuity worse than PL in one or both eyes; controlled IOP with medical treatment; intolerance to slit-lamp examination, tonometry, or other study procedures; mental impairment invalidating informed consent or disrupting follow-up; pregnancy; known sensitivity to medication needed during and after surgery; significant comorbid disease that might interfere with follow-up; and active clinical ocular infection requiring treatment.

All patients had preoperative complete ophthalmological examination (visual acuity using the Snellen's letters, anterior segment examination using slit-lamp bio-microscopy, and fundus examination using the slit-lamp bio-microscopy with a 90 D lens) and IOP measurement with a Goldmann applanation tonometer. The patients were examined postoperatively for IOP and any complications.

Surgical procedure of Ahmed valve was done as follows: after administration of regional or general anesthesia, a fornix-based conjunctival flap was fashioned in the superotemporal quadrant. The anterior edge of the plate was secured with 9–0 nylon sutures to the sclera at least 8 mm from the limbus. The tube tip was cut obliquely to protect the tube lumen from the iris. A 23-G needle tract was used to enter the anterior chamber 1 mm posterior to the limbus. The tube in the anterior chamber was positioned anterior to the iris and away from the corneal endothelium. Conjunctiva was sutured either with 8–0 polyglactin or 10–0 nylon sutures. The anterior chamber was reformed with basic saline solution through a paracentesis tract. Viscoelastic material was injected into the anterior chamber at the surgeon's discretion. The postoperative regimen included topical antibiotic and cycloplegic for 2–4 weeks and topical steroids for ~ 2 months.

The technique of cyclodiode laser photocoagulation was as follows: cyclodiode treatment was carried using a transscleral contact 'G-Probe' under peribulbar anesthesia. A lid speculum was inserted and the ciliary body was identified using a hand-held transilluminator. The heel of the contact probe was placed at the anterior aspect of the ciliary body, resulting in application about 1 mm behind this point. The normal treatment consisted of between 20 and 40 applications of 1.5 W energy applied over 1.5 s from 180 to 360°, and each burn therefore resulted in 2.25 J delivered. Following cyclodiode, topical steroids were applied 2–4 hourly for 2 weeks.

Statistical analysis

Data were fed to the computer and analyzed using IBM SPSS software package, version 20.0. (IBM Corp., Armonk, New York, USA). Qualitative data were described using number and percent. The Kolmogorov–Smirnov test was used to verify the normality of distribution. Quantitative data were described using range (minimum and maximum), mean, SD, and median. Significance of the obtained results was judged at the 5% level.

The used tests were c2 test for categorical variables, to compare between different groups, and Mann–Whitney test, or abnormally distributed quantitative variables, to compare between two studied groups. Friedman test was used for abnormally distributed quantitative variables, to compare between more than two periods or stages and post-hoc test (Dunn's) for pairwise comparisons. SPSS is short for statistical package for social science, and it is used by many researchers for complex statistical data analysis.

 Results



There was no significant difference among group I and group II regarding age, sex, and preoperative IOP [Table 1].{Table 1}

The mean postoperative IOP after 1 month for group I was 14.80 ± 4.10 and was 25.0 ± 6.68 for group II, with a significant difference (P = 0.004). The mean postoperative IOP after 3 months for group I was 16.80 ± 5.16 and was 22.30 ± 6.18 for group II, with a significant difference (P = 0.035). The mean postoperative IOP after 6 months for group I was 19.10 ± 5.74 and was 20.0 ± 7.44 for group II, with nonsignificant difference (P = 0.436) ([Table 2], [Table 3] and [Figure 1], [Figure 2]).{Table 2}{Table 3}{Figure 1}{Figure 2}

The percentage of IOP reduction was 54.16 ± 11.30 in group I and 51.95 ± 17.73 in group II after 6 months of follow-up. The difference between them was not significant (P = 0.481) [Table 4].{Table 4}

In Ahmed valve patients, the most frequent complication was hyphema (three patients). All the hyphemas were reabsorbed without any surgical intervention.

Encapsulated bleb and excessive tube fibrosis developed in two cases. Hypotony developed in one eye. Tube exposure developed in one eye. Neither phthisis bulbi nor any other severe complications were observed in any of the patients.

In patients who had DCPC, eye pain was the most frequently observed complaint, which was relieved within 1 or 2 days by oral analgesics. Conjunctival chemosis developed in three patients, which was self-limiting within 4 days. Anterior uveitis developed in two eyes and hypotony in one eye. Neither phthisis bulbi nor any other severe complications were observed in any of the patients [Table 5].{Table 5}

 Discussion



Refractory glaucoma presents a difficult management problem. A variety of methods exist for the treatment of patients in whom initial medical, laser, and surgical treatments have been unsuccessful in lowering IOP and thereby decreasing the progression of glaucomatous damage. Drainage procedures, such as antimetabolite augmented trabeculectomy, are a potential solution but may be associated with a number of complications, including hypotony, leaking blebs, and endophthalmitis[13].

Aqueous shunts are a reliable alternative to trabeculectomy[8]. However, their use may also be associated with some complications as listed in our study. Cyclodestruction is an older method of IOP control. Until the 1990s, this was not widely used because of the high incidence of phthisis and sympathetic ophthalmitis with relatively blunt treatment modalities such as cyclocryotherapy[14].

Since then, however, more precise and less destructive modes of cycloablative treatment have become available. These methods include external methods such as contact and noncontact YAG or DCPC and more recently still treatment via direct endoscopic ciliary body photocoagulation. All of these methods have been reported to achieve reasonable IOP control[15]. There are limited data that compare the success rate between DCPC and AGV implantation in the literature[16]. In our study, we tried to compare the success rates of DCPC and AGV implantation in refractory glaucoma. Both AGV implantation and cyclodiode laser achieved a marked IOP lowering effect (from a mean preoperative IOP 41.30 ± 3.53 mmHg to a 19.10 ± 5.74 mmHg at last visit) in AGV group, and preoperative IOP of 41.50 ± 3.31 mmHg to a 20.0 ± 7.44 mmHg at last visit in cyclodiode laser group. We found that IOP was lower in the AGV group compared with DCPC eyes within the first month postoperatively (P = 0.004). Six months after surgery, the IOP increased in the Ahmed glaucoma group but was still lower than cyclodiode laser group. However, the difference between two groups was not statistically significant (P = 0.436).

There are limited data in the literature that compare the success rates of DCPC and AGV implantation in a long-term follow-up study.

Recently, Lima et al.[16] compared long-term results of endoscopic DCPC and AGV implantation and found that there was no difference in the success rates.

More recently, Yildirim et al.[17] prospectively assessed cyclodiode or Ahmed tube surgery for neovascular glaucoma. Overall, no significant difference was found between the groups; 24-month success probability was 61.18 and 59.26%, respectively. Similar results have been reported by Noureddin et al.[18] when comparing noncontact cyclo-YAG with tube surgery for refractory glaucoma. In contrast, a small retrospective study by Chalam et al.[19] with only 6-month follow-up suggests that outcomes in neovascular glaucoma are better with pars plana Baerveldt tube surgery compared with cyclo-YAG.

A study by Bloom et al.[12], which was a retrospective study, compared among three modalities of treatment (tube surgery, cyclodiode laser, and cyclo-YAG laser) for the management of refractory glaucoma. All three methods were successful in producing IOP reduction, but the greatest lowering of IOP was achieved with tube treatment.

Differences between the present study and the aforementioned ones make direct comparison challenging. The type of tube surgery performed differs between both in type (Baerveldt vs. Ahmed vs. other). Some studies looked exclusively at neovascular glaucoma[17],[19], whereas others studied a heterogenous population[18]. It is also true that, in general, cyclophotocoagulation techniques are nonstandardized; this may influence efficacy. For these reasons, it is perhaps not surprising that different outcomes have been reported. Interestingly, despite the many differences, no study has yet found larger mean IOP reductions with cyclo-YAG or cyclodiode.

Both DCPC and Ahmed valve implantation have complications. In our study, the eyes that underwent AGV implantation had more complications than those treated with DCPC. The main complications in the DCPC group were anterior chamber uveitis and hypotonia; whereas in the AGV group, main complications were hyphema, tube exposure, encapsulated bleb, and hypotonia.

In the study by Schwartz et al.[20], tube shunt implantation has more complications not observed in DCPC procedures, such as tube exposure and cystic bleb formation, similar to the results of our study.

In a recent study by Mistlberger et al.[21] after DCPC the most frequently observed complication was anterior chamber inflammation, paralleling the findings of our study. They have also reported hyphema, choroidal detachment, and phthisis bulbi, which we have not observed in our study.

 Conclusion



This study revealed that after 6 months following cyclodiode laser or Ahmed valve, the greater IOP reduction was achieved by AGV, but the difference between it and DCPC was not significant. However, DCPC is less time consuming and easier method. AGV had more serious complications.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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