Ophthalmic Surgery, Lasers and Imaging Retina

Clinical Science 

A Novel Surgical Method to Treat Chronic Ocular Hypotony

Gökhan Gürelik, MD; Safak Korkmaz, MD; Gaye Disli, MD; Sabahattin Sül, MD

Abstract

BACKGROUND AND OBJECTIVES:

To assess the effect of a novel surgical method for the treatment of chronic ocular hypotony (COH). The surgical method involves partially blocking the iridocorneal angle and decreasing aqueous humor outflow. A capsular tension ring (CTR) is placed in the iridocorneal angle.

PATIENTS AND METHODS:

Thirteen eyes of 13 patients were included in this retrospective, interventional case series. All of the eyes had severe ocular hypotony with a diagnosis of hypotony after vitreoretinal surgery or glaucoma filtration surgery. A CTR was placed in the iridocorneal angle via a corneal incision. The follow-up period was at least 1 year. Main outcome measurement was intraocular pressure (IOP).

RESULTS:

IOP increased in all of the eyes. The increase in IOP persisted during the follow-up period. Visual acuity increased or stabilized in all of the eyes. No ocular complications were noted due to the procedure.

CONCLUSIONS:

The authors have described a novel and simple technique for the setting of IOP in COH. Mechanical obstruction of aqueous humor outflow with a CTR can increase IOP and stabilize or improve vision in eyes with COH for a follow-up time longer than 12 months.

[Ophthalmic Surg Lasers Imaging Retina. 2019;50:e56–e60.]

Abstract

BACKGROUND AND OBJECTIVES:

To assess the effect of a novel surgical method for the treatment of chronic ocular hypotony (COH). The surgical method involves partially blocking the iridocorneal angle and decreasing aqueous humor outflow. A capsular tension ring (CTR) is placed in the iridocorneal angle.

PATIENTS AND METHODS:

Thirteen eyes of 13 patients were included in this retrospective, interventional case series. All of the eyes had severe ocular hypotony with a diagnosis of hypotony after vitreoretinal surgery or glaucoma filtration surgery. A CTR was placed in the iridocorneal angle via a corneal incision. The follow-up period was at least 1 year. Main outcome measurement was intraocular pressure (IOP).

RESULTS:

IOP increased in all of the eyes. The increase in IOP persisted during the follow-up period. Visual acuity increased or stabilized in all of the eyes. No ocular complications were noted due to the procedure.

CONCLUSIONS:

The authors have described a novel and simple technique for the setting of IOP in COH. Mechanical obstruction of aqueous humor outflow with a CTR can increase IOP and stabilize or improve vision in eyes with COH for a follow-up time longer than 12 months.

[Ophthalmic Surg Lasers Imaging Retina. 2019;50:e56–e60.]

Introduction

Chronic ocular hypotony (COH) is an exhausting condition for both surgeons and patients. COH is not common after vitreoretinal surgery, but management is difficult. If it is due to fibrous proliferation and traction on the ciliary body, membrane dissection may increase intraocular pressure (IOP).1,2 However, the ciliary body is often affected by atrophy after repeated vitreoretinal surgeries. Dysfunction of the ciliary body and subsequent loss of aqueous production can eventually cause phthisis of the globe.3

Treatment approaches for COH include topical corticosteroid, ibopamine (a nonselective dopaminergic agent) and intravitreal corticosteroids, gas, viscoelastic, and silicone oils as temporary or prolonged vitreous substitute.4–8 However, some eyes still require permanent silicone oil tamponade to prevent phthisis bulbi. New methods to ensure complete recovery must be investigated.

In this retrospective case series, we describe a novel surgical method for treatment of COH, and we evaluate its long-term efficacy. The surgical intervention consists of partially blocking the iridocorneal angle using a capsular tension ring (CTR).

Patients and Methods

We retrospectively reviewed data from patients with COH treated with the novel surgical method at Gazi University Hospital in Ankara, Turkey, between 2011 and 2014. Informed written consent was obtained from all of the patients. The tenets of the Declaration of Helsinki were followed throughout the study, which was approved by the institutional review board.

COH was described as IOP less than 6 mm Hg measured by Goldmann applanation tonometry on three consecutive visits that had persisted for at least a 1-month period despite intensive anti-inflammatory and cycloplegic therapy.2,9 Duration of hypotony before surgery ranged from 1 to 3 months in all eyes. Patients factors and characteristics, including age, sex, previous therapies, best-corrected visual acuity (VA) at preoperative and postoperative visits, IOP, follow-up period, and additional treatments after surgery, were recorded.

Twelve eyes had ocular hypotony with a diagnosis of hypotony after vitreoretinal surgery for retinal detachment, and one eye had hypotony after glaucoma filtration surgery (trabeculotomy). Patients with cyclodialysis cleft, epiciliary membranes, and anterior proliferative vitreoretinopathy were excluded. Reported preoperative IOP was the last measurement immediately before surgery. Postoperative IOP at the last follow-up visit (final IOP) was considered the primary outcome measurement. The follow-up period was at least 1 year. Wilcoxon signed-rank test was used for evaluating differences before and after treatments.

The patients were divided into two groups: Group 1 included hypotonic eyes without silicone oil endotamponade, and group 2 included hypotonic eyes with silicone oil endotamponade. A CTR (11 mm to 13 mm) was placed in the iridocorneal angle via a corneal incision (Figures 1A–1C). On the first postoperative day and at follow-up visits, gonioscopy revealed the CTR occluding the iridocorneal angle in all eyes (Figure 1D), although it could not measure how much of the angle was occluded.

Capsular tension ring (CTR) insertion in the iridocorneal angle. (A) Limbal incision. (B) CTR insertion. (C) Intracameral air injection (in some cases). (D) Gonioscopy image of the CTR.

Figure 1.

Capsular tension ring (CTR) insertion in the iridocorneal angle. (A) Limbal incision. (B) CTR insertion. (C) Intracameral air injection (in some cases). (D) Gonioscopy image of the CTR.

Topical antibiotic and steroid drops were used four times a day for 2 weeks postoperatively and discontinued thereafter.

Results

Thirteen eyes of 13 patients (two females, 11 males) were included in the study. There were six eyes in Group 1 and seven eyes in Group 2. The mean age was 48.3 years ± 15.9 years (range: 20 years to 70 years). The mean postoperative follow-up time was 27.7 months ± 8.5 months (range: 14 months to 39 months).

The changes in VA and IOP after surgery in the 13 eyes with COH are shown in Table 1. The mean logarithm of minimum angle of resolution (logMAR) VA and IOP were significantly improved after surgery (Table 2).

Changes in VA and IOP in 13 Eyes With Chronic Ocular Hypotony AfterCapsular Tension Ring Implantation

Table 1:

Changes in VA and IOP in 13 Eyes With Chronic Ocular Hypotony AfterCapsular Tension Ring Implantation

Changes in logMAR VA and IOP in 13 Eyes With Chronic Ocular Hypotony AfterCapsular Tension Ring Implantation

Table 2:

Changes in logMAR VA and IOP in 13 Eyes With Chronic Ocular Hypotony AfterCapsular Tension Ring Implantation

All of the eyes were pseudophakic. The retina remained attached in all 13 eyes during the follow-up period. All of the patients underwent repeated retinal repair for retinal detachment except for one patient, who had hypotony after trabeculotomy (patient No. 4 in Group 1). Extensive peripheral retinal laser scars were present in all of the eyes that underwent repeated vitreoretinal surgeries. There was ciliary body atrophy in these patients.

IOP increased in all 13 eyes. Mean IOP improved significantly after surgery from 3.77 mm Hg ± 1.00 mm Hg to 8.31 mm Hg ± 3.40 mm Hg (P = .001). Eleven eyes (85%) had an IOP of at least 6 mm Hg. Vision increased or remained stable in all of the patients. Mean VA improved significantly after surgery from 1.73 logMAR ± 0.44 logMAR to 1.47 logMAR ± 0.52 logMAR. VA improved in seven eyes (54%) and remained unchanged in six eyes (46%); VA did not worsen in any eyes.

No ocular complications were observed due to the procedure. There was no sign of inflammation after CTR implantation. No eye developed phthisis bulbi. Mild corneal edema and mild maculopathy were present preoperatively in four eyes and disappeared during follow-up (patients No. 1 and 2 in Group 1; patients No. 3 and 5 in Group 2).

Discussion

We have described a novel method that provides long-term control of COH. Occlusion of aqueous outflow via implantation of a CTR in the iridocorneal angle yields an effective increase in IOP. The success of this technique is probably associated with the viability of the ciliary body.

COH is an important cause of functional failure after repair of retinal detachment despite retinal stabilization. Most often, COH after vitreoretinal surgery originates from ciliary body atrophy or traction on it related to epiciliary membranes and anterior proliferative vitreoretinopathy. Repeated retinal surgery, especially complicated with proliferative vitreoretinopathy, and excessive laser burns due to the insulating effect of silicone oil may induce ciliary atrophy.3

Hypotony represents a risk for the development of phthisis if left untreated. The efficacy of the treatment depends on the state of the ciliary body. Hypotony can be treated surgically if residual anterior contraction detaches the ciliary body. Removing epiciliary membranes and anteroposterior traction, with or without endoscopic viewing, provide a moderate increase in IOP.1,2,9 Long-acting perfluorocarbon gas or viscoelastics can be repeatedly injected to restore IOP and ocular architecture.4,7,10 Silicone oil can be injected as a permanent vitreous substitute if marked ciliary atrophy is present.11

Therapy for COH due to decreased aqueous production is limited because there is no method to improve ciliary body function. The primary pathway responsible for aqueous outflow is the trabecular meshwork. Minimizing aqueous outflow can be useful to increase IOP and preserve vision. Sclerosis of the trabecular meshwork with heavy argon laser burns showed improvement of IOP.12 In our study, hypotony was secondary to ciliary atrophy caused by direct damage of repeated vitreoretinal surgery and peripheral laser treatment. In the hope of increasing IOP, we attempted to reduce the trabecular outflow by implanting a CTR in the iridocorneal angle. There was no need for repeated surgeries and their associated risks.

IOP increased in all eyes in both groups in our study (Table 1). IOP rise was statistically significant (Table 2). Eleven (85%) of the 13 patients had a final IOP greater than 5 mm Hg and recovered from COH. Although there was a statistically significant VA rise (Table 2), VA increased in only seven eyes (54%) (Table 1). Increase in IOP but not in vision in the rest of the eyes, which preserved the eye from phthisis, was important, and retinal changes due to primary pathology were the cause of the limited vision. Some eyes experienced a better IOP rise. The difference in IOP rise between the eyes may be correlated with ciliary body function. IOP increased and stabilized at 18 mm Hg after CTR implantation in a patient (No. 4 in Group 1) whose IOP was 2 mm Hg after trabeculotomy. This finding shows that blocking the iridocorneal angle is more effective in eyes with a healthy ciliary body.

Intravitreal silicone oil has been used to maintain IOP in eyes with COH as a last resort.11,13 Hypotonia and subsequent phthisis can occur even in silicone-filled eyes.14,15 Some eyes may require repeated silicone oil injections.6 However, a toxic effect of silicone oil on the ciliary body may contribute to hypotony.16 Every surgery has also a risk of worsening hypotony.17 Our minimally invasive technique may represent a sustainable increase in IOP in silicone oil-filled eyes and can decrease the need for repeated surgeries such as filling the anterior chamber with viscoelastics to have an additional IOP rise. In addition, blockade of the aqueous outflow with a CTR supplied additional IOP increase in eyes having persistent hypotony despite silicone endotamponade and decreased likelihood of developing phthisis.

Despite the limitations, including retrospective design, lack of a control group, small sample size, and lack of data about corneal endothelial cell counts during follow-up, mechanical obstruction of aqueous humor outflow with a CTR may treat ocular hypotony and improve vision in selected eyes with COH if there is at least some amount of humor aqueous production, as was true for patients in both groups. The CTR obstructs the iridocorneal angle partially. Blocking the angle fully with new tools can enhance the effectiveness of this technique; we are exploring this work. Other prospective randomized studies are necessary to further evaluate the usefulness of this method for managing COH.

References

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Changes in VA and IOP in 13 Eyes With Chronic Ocular Hypotony AfterCapsular Tension Ring Implantation

Patient No.Intraocular Pressure (mm Hg)VAFollow-Up Month
InitialFinalChangeInitialFinalChange
Group 1
1264HM20/400Better39
2484HM20/200Better37
3312920/20020/70Better29
42181620/20020/100Better14
558320/40020/400Same18
6583CFCFSame17
Group 2
1451HMHMSame38
2363LPLPSame37
3352HM20/400Better25
4495CF20/400Better33
5484HMCFBetter27
658320/20020/200Same24
7572CFCFSame23

Changes in logMAR VA and IOP in 13 Eyes With Chronic Ocular Hypotony AfterCapsular Tension Ring Implantation

Initial (Range)Final (Range)Change (Range)P Value
IOP, mm Hg3.77 ± 1 (2 to 5)8.31 ± 3.4 (5 to 18)4.54 ± 3.9 (1 to 16).001
VA, logMAR1.73 ± 0.44 (2.3 to 1)1.47 ± 0.51 (2.3 to 0.6)0.26 ± 0.3 (0 to 1).017
Authors

From Gazi University Medical School, Department of Ophthalmology, Ankara, Turkey (GG); Düzce Atatürk State Hospital, Department of Ophthalmology, Düzce, Turkey (SK); 29 Mayıs State Hospital, Department of Ophthalmology, Ankara, Turkey (GD); and Muğla Sıtkı Koçman University Medical School, Department of Ophthalmology, Muğla, Turkey (SS).

This study was presented in part as a poster at the American Academy of Ophthalmology 2014 meeting.

The authors report no relevant financial disclosures.

Address correspondence to Safak Korkmaz, MD, Düzce Devlet Hastanesi, Göz Hastalıkları Bölümü, Düzce, Turkey 81000; email: korkmzs@gmail.com.

Received: January 15, 2018
Accepted: May 09, 2018

10.3928/23258160-20190301-12

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