Advanced Coats' disease: Treating the effect before the cause

Abstract

An 8-year-old child with Stage 3A Coats' disease and severe submacular lipid exudation was initially treated with intravitreal injections of bevacizumab followed by triamcinolone. The exudative retinal detachment was then treated by scleral buckling, cryotherapy of persistent telangiectasia, and subretinal fluid drainage. The residual telangiectasia on the reattached retina was finally ablated by photocoagulation. The patient had a near-total resolution of submacular hard exudates without macular fibrosis. The peripheral telangiectasia and exudative detachment also regressed, with the sustained recovery of excellent visual acuity.

Introduction

Coats' disease has been recognized and treated for over a century, with progressively improving globe salvage and visual outcomes due to earlier detection and aggressive treatment, including adjuvant pharmacotherapy.[1,2,3] The most common presentation is exudative retinal detachment (Stage 3A–B; nearly 70% of the cases).[3] The management outlook at this stage has remained defensive over the decades: globe preservation and preventing progression to the painful blind eye, rather than visual improvement.[2,4,5,6] The poor visual outcomes are usually secondary to macular fibroglial scarring,[2] which mostly follows macular fluid and hard exudates.[4] One way to improve the visual outcomes may be to reverse the timing and choice of treatment options: addressing the effect (macular exudate accumulation) before the cause (peripheral telangiectasia). However, the application of treatment modalities has only been sequenced as first medical and later surgical, without attention to the nitty-gritty of medical treatment.[1,2,3,5,6] A child with Stage 3A Coats' disease and profuse submacular exudation was successfully managed by initial pharmacotherapy of the macular exudates (effect), followed by scleral buckling, drainage of subretinal fluid, and treatment of the telangiectasia (cause) with cryotherapy and photocoagulation.

Case Report

An 8-year-old boy presented at our tertiary eye care center with visual loss OS for a few months. His best-corrected visual acuity (BCVA) was 20/20 OD and 20/250 OS. On examination, the right eye was normal. The anterior segment OS was unremarkable. Fundus OS showed copious submacular lipids and exudative retinal detachment extending from retinal telangiectasia in the inferotemporal periphery [Figure 1a and c]. The condition was diagnosed as Coats' disease Stage 3A2 (subtotal exudative detachment with foveal involvement) based on the Shields' updated classification.[2] With the informed consent of the parents, the left eye was injected with intravitreal bevacizumab 1.25 mg/0.05 ml. BCVA marginally improved to 20/200 within a month with minimal change in hard exudates; the exudative detachment and telangiectasia persisted. This time, intravitreal triamcinolone acetonide (IVTA) in half dose (2 mg/0.05 ml) was used. There was a significant reduction in macular hard exudates [Figure 1b and d] over a month; the BCVA remained 20/200; however, the telangiectasia and inferotemporal exudative detachment persisted [Figure 1e]. At this point, cryopexy of the telangiectasia, drainage of subretinal fluid, and an inferotemporal segmental buckle (#276) were performed. One month postoperatively, the retina was attached, the submacular exudates reduced further, and BCVA improved to 20/60. Targeted laser photocoagulation of the residual telangiectasia flattened over the buckle elevation was now performed. BCVA improved further to 20/40 over the next 1 year with a nearly total resolution of subfoveal hard exudates [Figure 1f and g]. The visual and anatomic recovery was maintained till the last follow-up at 3 years. The intraocular pressures were stable through the study. This study was performed in compliance with the tenets of the Helsinki Declaration. A waiver from the review was given by the Institutional Review Board for the retrospective compilation of this case study.

Figure 1.

Sequential pharmacotherapy of Coats' disease (a and c) Massive retinal exudates (b and d) resolved minimally postintravitreal bevacizumab; but dramatically postintravitreal triamcinolone. Submacular exudates begin to get organized. (e) Peripheral telangiectasia and detachment, unchanged postpharmacotherapy, (f and g) resolved after scleral buckling, cryotherapy, drainage of subretinal fluid, and subsequent photocoagulation

Discussion

In one of the largest and longest interventional studies of Coats' disease, Shields et al. presented 40 eyes with Stage 3A2 disease.[2] Only a fifth of these eyes improved to ≥20/40; the most common cause for poor final acuity being fibroglial scarring of the macula. A possible explanation could be the frequent use of cryotherapy and photocoagulation as primary intervention (75%–80% eyes), while IVTA was used in only 5% of the eyes. It is noteworthy that while subretinal fluid resolved in nearly three-fourths of the eyes, subfoveal hard exudates resolved in less than a fifth of the eyes.[2] Stanga et al. also reported complete fluid resolution and incomplete resolution of macular exudates in Stage 3A and B Coats' disease, resulting in good anatomic but poor visual outcomes using similar multimodal therapy, sans IVTA.[6] Anti-vascular endothelial growth factor (VEGF) agents (especially bevacizumab) have shown modest visual outcomes as standalone agents, or as adjuvants in Coats' with exudative detachment, and may occasionally precipitate a tractional retinal detachment.[1] Better anatomic and functional outcomes have been reported with IVTA in similar stages of Coats' disease.[7] The route of administration also matters: subtenon triamcinolone has been shown to be less effective for diabetic macular edema than IVTA, though it had similar side effects, especially on intraocular pressure.[8] Intravitreal dexamethasone also cleared subfoveal hard exudates faster than bevacizumab in the BEVORDEX trial.[9] The lipid clearance rate is more critical in Coats' disease than in diabetic macular edema because of much more severe exudation and, therefore, greater risk of macular fibrosis. However, intravitreal bevacizumab and posterior subtenon triamcinolone have been used interchangeably with IVTA as adjuvants in Coats' disease.[1,2,3,4,5,6]

Photocoagulation/cryotherapy of telangiectasia is the mainstay of treatment in Coats' disease, but resulting inflammation may precipitate macular fibrosis, both directly and by exacerbating already profuse macular exudation.[1] For macular exudation, intravitreal bevacizumab was preferred over IVTA due to concerns of secondary glaucoma and cataract with the latter, especially in a child's eye.[1] The suboptimal outcome with bevacizumab on exudation deterred a repeat injection. The patient was offered the option of a dexamethasone implant (Ozurdex@), arguably a safer corticosteroid option for children.[10] IVTA was used when the parents declined Ozurdex for financial reasons. Half-dose IVTA may be as effective as a full-dose drug, with less complications.[1] Once macular exudates were reduced, peripheral telangiectasia and detachment were treated with cryopexy, subretinal fluid drainage, and scleral buckling. The buckling was performed as a backup for incomplete drainage and to fully flatten the elevated telangiectasia to the retinal pigment epithelium, making them accessible to subsequent laser photocoagulation. Multimodal management has become the norm for Coats' disease currently, but there is less focus on the preferred sequence of application of treatment options and the choice of pharmacotherapy[1,2,3,4,5,6] Prior treatment of the macular lipid exudation, use of corticosteroid instead of repeating anti-VEGF injection, and treatment of the causative telangiectasia and exudative detachment at a later date avoided the imminent risk of submacular fibrosis and provided excellent anatomic and visual outcomes in advanced Coats' disease.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.