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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 21  |  Issue : 2  |  Page : 117-121

Management of refractory glaucoma using fixed-energy diode laser cyclophotocoagulation


1 Department of Ophthalmology, Faculty of Medicine, Aswan University, Aswan, Egypt
2 Department of Ophthalmology, Faculty of Medicine, Fayoum University, Fayoum, Egypt
3 Department of Ophthalmology, Faculty of Medicine, Tanta University, Tanta, Egypt

Date of Submission03-Nov-2019
Date of Decision12-Jan-2020
Date of Acceptance05-Feb-2020
Date of Web Publication26-Jun-2020

Correspondence Address:
FRCSEd, MD Ahmed F Gabr
19 Saif El-Dawla Street, Tanta 31111
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/DJO.DJO_60_19

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  Abstract 


Purpose The aim of this study was to evaluate the efficacy and safety of trans-scleral diode laser cyclophotocoagulation (TSCPC) using the fixed-energy technique in the management of patients with refractory glaucoma.
Patients and methods In this prospective study, 22 eyes of 22 adult patients with refractory glaucoma and visual acuity of less than or equal to 3/60 (≥1.3 logMAR) were included. Following complete ophthalmological examination, patients were treated with TSCPC using the slow coagulation technique. Follow-up of patients was done at 1 week, 1 month, 3 months, and 6 months, postoperatively. Postoperative complications were monitored and reported.
Results The mean age of patients was 57.1±10.6 years. There was no significant change in visual acuity or optic disk appearance between preoperative and postoperative visits in all cases. There was a significant reduction in mean intraocular pressure after 6 months of follow-up from 42.41±8.8 mmHg, preoperatively to 18.5±8.8 mmHg, postoperatively (P=0.02). The mean number of antiglaucoma medications was reduced significantly from 2.45±1.1, preoperatively, to 1.0±0.5, postoperatively (P=0.0001). Mild to moderate anterior chamber reaction was reported in 16 (72.7%) patients while hyphema was found in two (9%) patients and vitreous hemorrhage and transient hypotony due to choroidal detachment were encountered in one patient each. Six (27.27%) patients reported smooth postoperative course without any complications or pain.
Conclusion Fixed energy method of TSCPC represents an effective technique for the management of refractory glaucoma with low potential for serious complications.

Keywords: cyclophotocoagulation, diode laser, intraocular pressure, refractory glaucoma, trans-scleral diode


How to cite this article:
Gabr AF, Nassef MA, Othman TM, Hussein TR. Management of refractory glaucoma using fixed-energy diode laser cyclophotocoagulation. Delta J Ophthalmol 2020;21:117-21

How to cite this URL:
Gabr AF, Nassef MA, Othman TM, Hussein TR. Management of refractory glaucoma using fixed-energy diode laser cyclophotocoagulation. Delta J Ophthalmol [serial online] 2020 [cited 2020 Oct 30];21:117-21. Available from: http://www.djo.eg.net/text.asp?2020/21/2/117/287463




  Introduction Top


Different treatment modalities have been used for the management of refractory glaucoma; mainly shunt procedures such as the Ahmed glaucoma valve and cyclodestructive procedures [1]. Using the standard audible pops-titrated technique, trans-scleral diode laser cyclophotocoagulation (TSCPC) can be applied effectively inducing reduction of intraocular pressure (IOP) [2].

Although the use of high treatment energy can be associated with higher rates of controlled IOP [3], the risk for serious complications such as vision loss, hypotony, and phthisis represents a significant concern [4].

The aim of this study was to evaluate the efficacy and safety of TSCPC using the slow coagulation (fixed energy) technique in the management of refractory glaucoma.


  Patients and methods Top


In this prospective cohort study, consecutive patients with refractory glaucoma were included (having uncontrolled IOP ≥30 mmHg despite maximally tolerated antiglaucoma medications, previously failed nonseton surgical treatment, or both) [5].

The study protocol was approved by the Institutional Review Board and the Ethics Committee of the Faculty of Medicine, Aswan University and followed the tenets of the Declaration of Helsinki. All patients signed a written informed consent to participate in the study and for publication of data before enrolment in the study after full explanation of the procedure and its expected outcomes. Confidentiality of all data was ensured at every step of the study.

All the patients were above 18 years old, having dark irides [6],[7],[8] and with visual acuity less than or equal to 3/60 (≥1.3 logMAR) in the treated eye [9],[10]. Patients with visual acuity less than or equal to 3/60 (≥1.3 logMAR) in the other (nontreated) eye and patients with previous cyclodestructive procedure in the same eye were excluded [11].

The data obtained from previous studies, with a study power of 80% and type-I error of 5% indicated that a minimum sample size of 22 patients was required to demonstrate a statistically significant difference in outcome between prelaser and postlaser treatments [12],[13].

Complete history taking including patients’ age, race, sex, type of glaucoma, underlying ocular disease, antiglaucoma medications, previous glaucoma surgeries, and other ocular surgeries was obtained from all patients. Full ophthalmological examination then followed including visual acuity testing, IOP measurement by Goldman applanation tonometer (Shin-Nippon, Ohira Co. Ltd., Minamiuonuma, Niigata, Japan), and slit lamp biomicroscopic examination of the anterior segment and optic nerve head evaluation whenever possible.

The procedure was done under peribulbar anesthesia using 1 : 1 mixture of lidocaine 2% (Xylocaine; AstraZeneca, Cambridge, UK) and bupivacaine 0.5% (Marcaine; AstraZeneca). All eyes were treated with the slow coagulation technique of trans-scleral cyclophotocoagulation using G-probe of 810 nm diode laser (Iris Medical OcuLight SLx; Iridex Co., Mountain View, California, USA). Settings applied were: power of 1200 mw and 3500–4000 ms duration for 16–20 applications at 360° around the limbus avoiding 3 and 9 O’clock positions. Following the procedure, topical steroids and cycloplegic eye drops were given and patients’ antiglaucoma medications were adjusted according to the IOP measured during the follow-up period.

Follow-up of visual acuity, IOP, optic disk appearance, pain monitoring, and postoperative complications was done 1 day, 1 week, 1 month, 3 months, and 6 months, postoperatively.

Postoperative pain was evaluated using the verbal rating scale (VRS) [14]. In addition to topical prednisolone acetate 1% (Optipred; Jamjoom Pharma Ltd, Nasr City, Cairo, Egypt) and cyclopentolate 1% (Cycloplejico; Alcon Cusi, S.A. El Masnou, Barcelona, Spain), systemic 1000 mg paracetamol (Perfalgan; Bristol-Myers Squibb, Uxbridge, UK) by intravenous daily infusion as well as oral Ketoprofen 150 mg (Bi-Alcofan; Alexandria Co. Pharm. Chem. Ind., Alexandria, Egypt) was given when needed to control pain. Postoperative uveitis was graded as follows: mild uveitis, 6–15 cells; moderate uveitis, 16–25 cells; marked uveitis, 25–50 cells; and intense uveitis, greater than 50 cells using a 1×1 mm slit beam [15].

Statistical analysis

Data were statistically described in terms of mean, SD, median and range when appropriate. Comparison between the preoperative and postoperative data was done using Student’s t test. P values less than 0.05 were considered statistically significant. All statistical calculations were done using computer programs SPSS (the Statistical Package for the Social Sciences; SPSS Inc., Chicago, Illinois, USA) version 15 for Microsoft Windows.


  Results Top


Twenty-two eyes of 22 patients with refractory glaucoma were included. The mean age of the patients was 57.1±10.6 years (range=34–80 years). Twelve (54.55%) patients were men and 10 (45.45%) patients were women.

Causes of refractory glaucoma included chronic angle closure (CCG) in 10 patients, neovascular glaucoma in eight patients, aphakia/pseudophakia as well as silicon-oil-associated glaucoma in six and four patients, respectively.

There was no difference in the mean visual acuity in patients before and after 6 months of the procedure (1.87±0.01 and 1.89±0.01 logMAR, respectively, P=0.49) with no reported loss of vision in any of the treated eyes.

Mild to moderate postoperative pain was reported in 15 (68.18%) patients [12 (54.54%) patients experienced mild discomfort while three (13.63%) patients had moderate pain]. All were completely relieved with postoperative medications.

The mean IOP dropped 6 months after the procedure, from 42.41±8.8 mmHg, preoperatively, to 18.54±8.8 mmHg, postoperatively (P=0.02, [Table 1]). The mean reduction of IOP ranged from 15 mmHg at the first day to reach 24.87 mmHg after 6 months postoperatively ([Figure 1]). In addition, there was a significant reduction in the mean number of antiglaucoma medications from 2.45±1.1, preoperatively, to 1.0±0.5 after 6 months from laser treatment.
Table 1 Mean intraocular pressure during the follow-up period

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Figure 1 Intraocular pressure with interquartile range at different follow-up periods. IOP, intraocular pressure; preop, preoperative; postop, postoperative.

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Mild anterior chamber reaction was reported in 13 (59.1%) patients, while moderate reaction was found in three patients only (13.63%). Postlaser uveitis was completely relieved by the end of the first month of follow-up. Mild hyphema was reported in two (9%) patients and resolved within 2 weeks of postoperative treatment. Other complications noticed included vitreous hemorrhage and choroidal detachment associated with transient hypotony in one patient each. Adverse effects were transient and all resolved completely within 2 months of follow-up. Six (27.27%) patients experienced smooth postoperative period without noticeable complications

Transient hypotony (IOP 5 mmHg) was noticed in one patient who had choroidal detachment, which resolved after 2 months of follow-up and hypotony improved 3 months later.


  Discussion Top


Two techniques are used for continuous diode laser trans-scleral cyclophotocoagulation: standard (audible pops) technique and slow coagulation technique [16]. The slow coagulation technique was found to have a relatively smooth postoperative period with fewer and less severe postoperative complications [17]. Serious complications were reported to be associated with the use of high treatment energy protocols [4]. Therefore, some investigators advise a more cautious approach and initial delivery of a relatively low dose of diode laser energy to minimize the risk of hypotony [6].

In this study, neovascular glaucoma was found to be the second most common cause of refractory glaucoma. This coincides with the reduced incidence of neovascular glaucoma that accompanied the introduction of antivascular endothelial growth factor [18].

Loss of two Snellen’s lines or more of visual acuity was reported with long-term follow-up of eyes treated with trans-scleral cyclophotocoagulation standard protocol [19],[20],[21]. Contrary to this, in this study, we found no significant decrease in visual acuity in the treated eyes. This finding could be due to the less aggressive laser parameters used by the slow coagulation technique, the potentially very low visual acuity (≥1.3 LogMAR) of the selected patients, and/or by the relatively short follow-up period (6 months) in this study.

By the end of 6 months, the slow coagulation technique has resulted in the reduction of the IOP and a decrease in the number of antiglaucoma medications comparable to that reported with the standard protocol in previous studies [21],[22],[23],[24]. No carbonic anhydrase inhibitors or pilocarpine were needed after diode cyclophotocoagulation and 13 (59.1%) patients had stopped topical medications completely.

One eye (4.5%) presented with transient hypotony (IOP 5 mmHg) due to choroidal detachment that remained for 2 months and the hypotony improved before the sixth month. The incidence of long-term hypotony following standard TSCPC was reported to range from 0 to 18.8% [5],[25],[26],[27],[28]. During their study Stevenson-Fernandez et al. [10] correlated the occurrence of hypotony to the use of fixed energy (non-titratable) treatment as in the case of this study. Postoperative complications such as pain, mild anterior chamber reaction, and hyphema were noticed as previously reported by other investigators [2],[3],[22],[26].

The present study demonstrated an alternative method regarding the use of diode laser trans-scleral cyclophotocoagulation in the treatment of refractory glaucoma. Encouraging results regarding IOP control and reduction of the number of antiglaucoma medications were obtained with relatively few transient complications and without additional expenses to the patients.

Among the number of limitations, the study focused on the degree of IOP reduction overlooking the concept of target pressure and the functional effect of the drop in IOP. More randomized multicenter studies are needed to compare the slow technique with the standard method for trans-scleral cyclophotocoagulation or with the recently introduced micropulse technique. In addition, a study of a larger size group of patients with better visual acuities will be required to evaluate not only the reduction of IOP as a sole parameter, but also the optic nerve function, retinal fiber layer thickness as well as visual field changes.


  Conclusion Top


Using the fixed energy (slow coagulation) technique for TSCPC represents an effective method for the management of refractory glaucoma with low potential for serious complications.

Acknowledgements

The authors acknowledge the staff members of Ibn Sina Eye Center, Tanta, Egypt for their technical help and support.

The research was funded by the resources of Ophthalmology Department, Faculty of Medicine, Aswan University.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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