Surgical Management of Advanced Coats Disease in 32 Eyes: A 20-Year Study

Abstract

Purpose:

This work studies outcomes of external subretinal fluid (SRF) drainage in management of eyes with advanced Coats disease.

Methods:

Patients with advanced-stage Coats disease (≥stage 3B), who were younger than 12 years and underwent external SRF drainage from 1996 to 2016, were included in this retrospective study. Surgical intervention involved external drainage of SRF and cryotherapy. SRF drainage was performed by lamellar scleral dissection or by external needle drainage. Favorable anatomical outcome was defined as retinal reattachment with normal intraocular pressure (IOP). IOP greater than 24 mm Hg was considered raised. Univariate and multivariate analyses were performed to measure the association between preoperative or intraoperative factors and retinal status at final follow-up. Outcome measures evaluated included visual acuity, IOP, retinal status, globe status, and complications of surgery. Kaplan-Meier analysis was performed for globe salvage without pain.

Results:

Thirty-two eyes of 32 patients were included in the study. Mean age at surgery was 3.8 ± 3 years. The mean duration of follow-up was 7 years (range, 6 months-15.7 years). Improvement in visual acuity was seen in 5 eyes. Retina was attached at final visit in 6 eyes. IOP in the range of 8 to 24 mm Hg was noted in 16 eyes. Favorable anatomical outcome was achieved in 3 (9%) eyes. Globe salvage was achieved in 84% of eyes. Complications included intraoperative vitreous hemorrhage (n = 1) and postoperative inflammation (n = 1). Kaplan-Meier ocular survival rate without pain at 10 years was 76%.

Conclusions:

SRF drainage and cryotherapy in eyes with advanced Coats disease favorably alter the natural history of the disease and prevent end-stage complications. Visual outcomes remain poor.

Introduction

Coats disease is characterized by unilateral idiopathic retinal telangiectasia that is often associated with subretinal fluid (SRF) and exudation. ^{1 -3} The progressive nature of the disease has been established by several studies. ^{4 -6} Silodor et al, ⁴ Morales, ⁷ and Char ⁵ have reported the natural history of Coats disease, suggesting a bimodal peak, one in early childhood and the other in late adolescence or middle age. Management of Coats disease is primarily aimed at prevention of complications. Several management strategies, singly or in combination, have been attempted with varied results. ^{8 -10} Conventional treatment of Coats disease revolves around laser photocoagulation or cryotherapy to the retinal telangiectatic vessels aimed at cessation of exudation. ^11,12 The role of intravitreal antivascular endothelial growth factor agents as a treatment option in Coats disease is controversial. ^{13 -15} The risk of hyaloidal contraction evolving into tractional retinal detachment exists with intravitreal antivascular endothelial growth factor use. ^{16 -18} Intravitreal triamcinolone may enhance the absorption of SRF and exudates, but it is associated with complications like cataract in as many as 40% of cases and secondary glaucoma in 6% of cases. ¹⁹

In cases with complex retinal detachment and extensive exudation, pars plana vitrectomy with or without tamponade has been attempted and reported to be effective. ^20,21 However, extensive proliferative vitreoretinopathy can occur when retinotomy is used for SRF drainage. ²¹ External SRF drainage in Coats disease, described as early as 1970, can prevent progression to end-stage complication, thus resulting in globe salvage. ^{22 -24} It can at times also result in retinal reattachment and improvement in visual acuity (VA). ^25,26 External SRF drainage is easier to perform, less invasive, and rarely associated with complications compared with vitrectomy. It requires a short operation time and can be performed in cases with corneal haze as well. ²⁷ Herein, we report a series of patients with advanced Coats disease that is managed with external drainage of SRF with the intention of making the telangiectatic vessels more amenable to treatment with cryotherapy, resulting in resolution of exudation and eventual retinal reattachment.

Methods

A retrospective review of medical records of patients with advanced Coats disease treated with external SRF drainage between 1996 and 2016 was conducted. The study adhered to the tenets of the Declaration of Helsinki. The diagnosis of Coats disease was made based on clinical examination and ultrasonography. Staging of the disease as proposed by Shields and Shields ²⁸ was followed, where advanced stage was stage 3B or greater. Eyes with rubeosis iridis or previously treated eyes were excluded. Patients with a follow-up shorter than 6 months were also excluded. Data included patient demographics, clinical characteristics at presentation, details of treatment, and anatomical and functional outcomes.

Ultrasound B-scan examination was performed in all eyes prior to surgery. Surgical intervention involved SRF drainage either by lamellar scleral dissection or with a 26-gauge needle mounted on silastic tubing attached to a 10-cc syringe used in the quadrant of maximum bullous retinal elevation (Figure 1). Double freeze-thaw cryotherapy was performed to the retinal telangiectatic vessels. Encirclage with a number 240 silicone band was performed at the treating surgeon’s discretion (Figure 2). Intraoperative hypotony was managed with intraocular injection of saline through the limbus or pars plana route.

Figure 1.

Technique of external subretinal fluid (SRF) drainage. External image of an eye with an (A) extremely bullous retinal detachment and (B) anterior chamber maintainer in situ. (C) Scleral cut down for SRF drainage is performed in the same quadrant as the anterior chamber maintainer (preferably inferotemporal quadrant; arrow). The bulging choroidal knuckle is treated with (D) thermal cautery to minimize bleeding risk from (E) needle-assisted choroidotomy and (F) achieve unhindered SRF drainage.

Figure 2.

(A) Preoperative fundus photograph reveals total retinal detachment with extensive subretinal exudation. (B) Optos fundus photograph 6 weeks after subretinal fluid drainage reveals complete retinal reattachment with peripheral indentation from the encirclage (arrows) and resolving subretinal hemorrhage in the nasal and inferior quadrants.

At each follow-up, patients were evaluated for functional and structural changes. These included measurements of best-corrected VA and intraocular pressure (IOP); slit-lamp evaluation for rubeosis, lens opacification, and inflammation; and detailed posterior segment evaluation of stage, zone, and extent of disease. For infants, VA of the affected eye was assessed for fixation and followability of light. For VA in children younger than 1 year, fixation was checked using the central/steady/maintained method. For children aged 1 to 2 years, preferential looking tests, such as LEA’ Grating Paddles or Teller Acuity, were used. For children aged 2 to 3 years, the Cardiff Acuity Test/LEA symbol matching was used. For children older than 3 years, LEA symbol matching was used. For school-aged verbal children, Snellen VA was used. IOP greater than 24 mm Hg was considered raised. Improvement was defined as a reduction in severity of exudation or stage of the disease.

SPSS version 22 (IBM SPSS Statistics, IBM Corporation) was used for statistical analysis. A P value of less than .05 was considered significant. Univariate and multivariate analyses were performed to determine the preoperative/intraoperative factors that influence postoperative retinal status. Kaplan-Meier analysis was performed for globe salvage without pain.

Results

In this retrospective study from January 1996 to December 2016, 43 eyes of 43 patients underwent SRF drainage with cryotherapy as treatment of advanced Coats disease. However, 11 patients did not have a follow-up of at least 6 months and were excluded from analysis, leaving 32 eyes of 32 patients (right eye = 17, left eye = 15) in the study. Twenty-seven boys and 5 girls were included in the study. The mean age at presentation was 3.8 ± 3 years (range, 1-12 years). Mean duration of complaints was 3.3 ± 3.6 months (range, 1 week-1 year). The most common presenting symptom, leukocoria, was noticed in 56% of eyes (n = 18), followed by decreased vision in 33% (n = 12), strabismus in 28% (n = 9), red eye in 16% (n = 5), and pain in 6% (n = 2). At presentation 2 eyes had an IOP less than 8 mm Hg, and 6 eyes had an IOP greater than 24 mm Hg. Two eyes had an intraretinal cyst, and 1 eye had a fixed retinal fold suggestive of chronicity of retinal detachment.

External SRF drainage was performed by lamellar scleral dissection in 9 eyes (28%) and with a 26-gauge needle mounted on silastic tubing in 23 eyes (72%). It was supplemented with transscleral cryotherapy to the telangiectatic retinal vessels. Additional laser was performed in areas with no or minimal SRF in 2 eyes. Cytopathologic examination of the drained SRF was performed in 19 eyes and showed the presence of eosinophils in 13 eyes, macrophages in 11 eyes, lymphocytes in 9 eyes, red blood cells in 6 eyes, neutrophils in 5 eyes, monocytes in 3 eyes, and uveal pigments in 5 eyes; 2 samples were acellular.

Intraoperatively, a single case of vitreous hemorrhage was noted that resolved spontaneously without any sequelae. Postoperatively, 1 patient had a fibrinous reaction in the anterior chamber in the first week that resolved with topical steroids.

At 6 weeks’ follow-up, reduction in exudation with partial retinal attachment was seen in 17 eyes (53%). IOP was maintained between 8 and 24 mm Hg in 27 eyes (84%). Re-treatment with laser photocoagulation was performed in 13 eyes, transscleral cryotherapy in 1 eye, and a second external SRF drainage in 1 eye.

The patients had a mean duration of follow-up of 7 years (range, 6 months-15.7 years). At final visit, VA improvement was seen in 5 eyes (16%).VA outcomes are given in Table 1. IOP was within 8 and 24 mmHg in 16 (55%) eyes, less than 8 mmHg in 10 (35%) eyes, and more than 24 mm Hg in 3 (10%) eyes. Retina was attached at final follow-up in 6 (19%) eyes. Five eyes progressed to phthisis, 3 of which were eviscerated. Globe salvage was achieved in 27 (84%) eyes. Favorable anatomical outcome, which was defined as retinal reattachment with normal IOP, was achieved in 3 (9%) eyes. Kaplan-Meier survival rate for globe salvage without pain at 10 years was 76% (Figure 3). On univariate binary logistic regression analysis, age of the patient, duration of complaints, type of SRF drainage, or placement of encirclage were not found to have an association with retinal status at final follow-up.

Table 1.

Visual Acuities at Presentation and Final Visit.

Visual acuity	At presentation	Final visit
≥ Counting fingers	2	3
HMCF	3	1
Fixates and follows light	1	0
Fixates	1	1
No fixation	15	6
Perception of light	6	2
No light perception	4	16

Abbreviation: HMCF, hand motion–counting fingers.

Figure 3.

Kaplan-Meier 10-year survival analysis for globe salvage without pain.

Conclusions

Historically, most infantile Coats disease eyes were enucleated because of the possibility of retinoblastoma. ^{7,29 -31} The Morales series noted this to be as high as 72% (13 of 18). ⁷ Silodor et al followed 13 children over a mean 21.2 months to study the natural history of Coats disease and noted that children with bullous detachment of the retina at presentation had a higher chance of developing neovascular glaucoma (NVG) and a painful blind eye. ⁴ The incidence of NVG in untreated cases in the series by Silodor and colleagues and Harris was 66.6% and 25%, respectively. ^4,23 SRF drainage prevented progression to painful NVG in 91% of eyes in our series.

Tarkkanen and Laatikainen found cryotherapy to be more effective than photocoagulation in the “more advanced cases and in the far periphery.” ³² The drainage of subretinal exudative fluid and/or the placement of a scleral buckle may help improve the relationship between the neural retina and retinal pigment epithelium in advanced cases of Coats disease. ^4,31 The Silodor et al case series proposed the use of intraocular infusion, drainage of SRF, and cryotherapy as a better option than no treatment in length of preservation of eyes as cosmetically acceptable, pain-free organs. ⁴ On the other hand, there are instances of spontaneous regression of advanced Coats disease. ^6,7,33 ; however, we do not yet know which cases and what mechanisms result in such regression. Following SRF drainage, 53% of eyes had reduction of exudation. In the studies by Adam et al and Stanga et al, all cases had complete elimination of SRF. This difference might be owing to the additional action of bevacizumab used in the study by Stanga and colleagues. ^25,27 Following the external SRF drainage procedure globe salvage was achieved in 84% of eyes in our series.

A minimally invasive procedure of external SRF drainage can prevent progression of Coats disease to NVG and phthisis bulbi and result in ocular salvage. This can prevent the psychological trauma of facial disfigurement at a young age. The procedure is also repeatable. Han et al in a review of cases of Coats disease drained with external drainage of SRF found impressive structural outcome without NVG in all 21 eyes in the study (100%). ²² We had a low incidence of NVG (9.4%) compared with no treatment (25% to 100%) and superior structural stability (84%). These factors merit the consideration of this treatment in advanced cases of Coats disease.

Many authors have alluded to the late recurrence of Coats disease, ranging from 2 to 5 years after initial treatment. ^31,33,34 Shienbaum and Tasman highlighted such scenarios of recurring exudation and telangiectasia in treated Coats disease, with the average time to first recurrence being 4.3 years and average number of recurrences being 3.3 (range, 1-5 years). ³⁴ The present study had an average follow-up of 7 years (range, 6 months-15.7 years) without any recurrence in the treated cases. However, a longer follow-up with a larger cohort of patients is required to substantiate the beneficial effects of the treatment on the onset, number, and duration of recurrences of retinal exudation.

The mean age of the children in our study group was younger than 5 years, precluding Snellen VA measurement in many. Also, these study results may not be applicable to cases treated with external drainage and laser treatment. Because our study period was expansive, fluorescein angiography was not always possible. However, of late we do use fluorescein angiography in cases with persistent retinal exudation to identify potentially untreated areas. Another limitation of the study is the variability in follow-up and its retrospective nature.

Advanced Coats disease presents a challenging situation to the treating surgeon. It is imperative that effective treatment be instituted at the earliest before end-stage complications set in. External drainage of the SRF with cryotherapy to retinal telangiectatic vessels helps in arresting the disease progression and preventing end-stage complications; however, visual outcomes remain poor.