Successful outcome of adult-onset Coats' disease following retinal laser photocoagulation.

Introduction

Coats’ disease is a form of retinal telangiectasia with lipid-rich subretinal exudates. It is mainly a disease of childhood and only on rare occasions has it been described in adults. In adults, it typically has a more insidious clinical course.[1] In this article, we report a case of adult-onset Coats’ disease that presented with macula involvement and was treated with laser photocoagulation with good outcome.

Case Report

A 23-year-old male, with no previous medical history, presented to our eye clinic with increasing paracentral scotoma in the right eye of 2 months duration.

On examination, best corrected visual acuity (BCVA) was twenty out of twenty (20/20) in both eyes, with normal intraocular pressure. Fundal examination of the right eye showed extensive hard exudates in the superior retina extending close to the fovea [Figure 1]. No abnormalities were seen in the left eye. Fundal fluorescein angiogram (FFA) revealed early hyperfluorescence of telangiectatic, leaking vessels in the superior temporal and nasal regions and hypofluorescence consistent with the subretinal exudates in the right eye. Optical coherence tomography (OCT) showed increased macular thickness. A diagnosis of adult-onset Coats’ disease was considered.

Figure 1

A montage of fundal images before treatment, with hard exudates and telangiectatic vessels in the superior retina

The telangiectatic vessels in the superior temporal and nasal retina were treated with direct laser photocoagulation and scatter retinal photocoagulation was applied to the rest of the superior retina. Five months after presentation, the exudates had decreased and there was resolution of the angiomatous changes [Figure 2a and b]. BCVA remained stable at 20/20. There was no recurrence of disease after 3 years of follow-up.

Figure 2

(a and b) Resolution of angiomatous changes and a decrease in hard exudates after scatter panretinal photocoagulation

Discussion

Despite the benign nature of Coats’ disease in adults, loss of VA can still result from macula involvement. This can occur through (1) macula edema and exudates, (2) development of an epiretinal membrane, and (3) foveal ischemia with enlargement of the foveal avsacular zone.[1] Exudative retinal detachment has been reported as a possible complication of untreated cases.[2] Hemorrhage, atypical of childhood Coats, may occur from macroaneurysms. Rubeosis iridis and neovascular glaucoma are rare.[1]

The treatment of Coats’ disease is guided by Shield's classification.[3] The goal is to obliterate telangectasia to stop exudation. This can be accomplished by argon or xenon laser photocoagulation or cryocoagulation. Vitreoretinal surgery is performed for advanced stage disease with retinal detachment and may also be indicated to treat epiretinal membranes or hemorrhage. Recent studies have shown promising evidence with the use of intravitreal anti-vascular endothelial growth factor (anti-VEGF).[4] Given the less aggressive nature of adult-onset Coats’ disease, an initial conservative approach can be adopted with vigilant monitoring for progression of disease or development of complications.[5] However, it is prudent to consider early laser photocoagulation if there is impending macula involvement, or if large amounts of exudates are seen.[2]

Conclusion

In conclusion, while Coats’ disease is primarily a disease of childhood, we must consider its diagnosis in adult patients exhibiting a retinal vasculopathy with prominent exudation. Though adult-onset Coats’ disease tends to follow a benign course, treatment should not be delayed if there is risk of macular involvement. Timely treatment with laser photocoagulation can confer excellent outcomes, with near-total to total restoration or preservation of vision.