COATS DISEASE


Imagine taking your baby, at that time 12 years old, for a routine eye examination, and being told they found "something" and it may be life-threatening! The students of optometry and the doctors on staff at W. W. Hastings Indian Health Care Hospital were at a loss. They had never seen a case of Coats Disease before, although they had studied it in medical school.One doctor had been in practice over 45 years, and he never had actually seen a case of this disease. My son, Marc and I and Dad, went to a specialist 60 miles away, and was told what the treatments were. He said Coats Disease is dominant in males, and lies dormant in families up to 100 years or more, and the statistics of having it develop are 1 in a million people! And, MY baby had to have it! I was devastated, as was the entire family. We didn't know what it was, or how life threatening it really was. The specialist said he would do kyro surgery and freeze the area to hopefully stop the growth. He did, and so far, my son is not having any more growth at age 18. Read about this disease below and be more informed.



Background: In 1908, George Coats first described this disease, delineating the following 3 groups of ocular diseases: group I includes those with massive subretinal exudate and choroidal mononuclear infiltrates but no vascular abnormalities, group II includes those with massive subretinal exudates and multiple retinal vascular abnormalities with intraretinal hemorrhage but no choroidal inflammatory infiltrate, and group III includes those with massive subretinal exudate and definite retinal arteriovenous malformations.

Subsequently, similar ocular manifestations were described in several disease entities, angiomatosis retinae (Eugen von Hippel) and Leber miliary aneurysm disease (Theodor Leber, 1912 and 1915). Reese confirmed the latter when eyes with Leber miliary aneurysms were observed to progress into typical Coats disease. Many authorities believe that Leber disease is an early or nonprogressive form of Coats disease.

Over the years, the classification of exudative vasculopathy has been controversial. Some authors argue that only cases of exudative vasculopathy with childhood-onset are Coats disease, while others have included adult-onset cases in their definition. While some authors have grouped exudative vasculopathies based on their clinical features and appearances regardless of the location of retinal vascular abnormalities, others have tried to subgroup exudative vasculopathies geographically. Currently, Coats disease is defined as an exudative vasculopathy that is characterized by the presence of vascular anomalies. It is associated with telangiectatic vessels, venous dilation, microaneurysms, and fusiform capillary dilation. The latter may be associated with exudative retinal detachment and a degree of capillary nonperfusion as defined by clinical examination and fluorescein angiography.

Pathophysiology: While the initial characterization of Coats disease was based on the disease morphology and microscopic histologic changes, the exact pathophysiologic mechanism remains unknown. This exudative vasculopathy is neither inherited nor associated with systemic vascular abnormalities, but ocular disorders, such as retinitis pigmentosa, may be seen with retinal telangiectasia.

Some believe that Coats disease may have a primary vascular etiology. In support of this assertion, marked thickening of the endothelial basement membrane of the telangiectatic vessels from the deposition of periodic acid-Schiff (PAS) positive material has been demonstrated. Histopathologic specimens from enucleated eyes, examined by both light and electron microscopy, revealed general loss of vascular endothelium and pericytes, subsequent mural disorganization, and loss of the blood-retinal barrier.

Similar to diabetic retinopathy, retinal vessels mostly are affected and may result in accumulation of subretinal lipid and hemorrhage. Unlike diabetic retinopathy, the subretinal lipid exudation of Coats disease is usually massive, and there is rarely intraretinal exudation or hemorrhage. In Coats disease, the abnormal vessels, exudates, and hemorrhages usually are located in the macular and/or supertemporal regions of the fundus. In contrast to Eales disease, venous sheathing or other signs of massive inflammation are not present in Coats disease.

Frequency:

Mortality/Morbidity:

  • While no specific connection has been made between Coats disease and any systemic disease, isolated coincidences of Coats disease with some disease entities, including retinitis pigmentosa, Senior-Loken syndrome, mental retardation, and muscular dystrophy, have been reported.
  • The clinical course generally varies. Although most cases are progressive, spontaneous remissions have been reported. Acute exacerbations of the disease usually are separated by periods of disease inactivity. The development of subretinal choroidal neovascularization in areas of lipid deposition promotes the formation of subretinal exudation and subsequent retinal detachment and/or hemorrhagic retinal macrocysts. Other complications in Coats disease include iridocyclitis, cataract, and secondary neovascular glaucoma.

Race: No reported racial or ethnic predilection exists.

Sex: When the age of onset is younger than 20 years, Coats disease appears to affect males 10 times more than females.

Age: See Sex.

  • The age distribution of Coats disease appears to correlate with prognosis. In children younger than 4 years, the disease has a poor prognosis with increased severity and rapid progression.
  • The disease has been diagnosed as early as birth.
History:
  • Coats disease is a predominantly unilateral retinal developmental vasculopathy seen in two forms, the earlier form (<20 y) and the adult form (>20 y). This disease is observed mostly in males who are younger than 20 years.

Physical: In addition to the history, a detailed ophthalmologic examination is important to exclude other diseases, which can be confused easily with Coats disease (see Imaging Studies).

  • The initial presentation of these patients may be leukocoria due to exudative retinal detachment and/or crossed eyes (strabismus due to foveal ectopia).
  • Funduscopic examination usually reveals retinal microaneurysms, exudates, and "light-bulb" vascular dilatations.
    • The characteristic fluorescein angiographic feature of Coats disease is temporal quadrant capillary nonperfusion with leaking microaneurysms. Commonly, telangiectasia, aneurysms, venous beading, and vascular communicating channels are seen.
    • These anomalous vessels demonstrate early and persistent leakage, implicating them as the source of the exudation and hemorrhage. These leakages correspond to areas of breakdown in the blood-retinal barrier.

Causes:

  • The exact etiology is unknown. Evidence suggests that Coats disease may have a primary vascular etiology. See Pathophysiology.

Branch Retinal Vein Occlusion
Cataract, Congenital
Eales Disease
Retinal Detachment, Exudative
Retinoblastoma
Retinopathy of Prematurity


Other Problems to be Considered:

Collagen vascular disease
Diabetic vasculopathy with lipid deposition
Epiretinal membrane with secondary vascular leakage
Familial exudative vitreoretinopathy
Idiopathic juxtafoveal telangiectasia
Myelinated nerve fibers
Norrie disease
Persistent hyperplastic primary vitreous
Toxocariasis
Uveitis
Vasculitis



Imaging Studies:

Other Tests:

Histologic Findings: Histopathologic specimens from enucleated eyes, examined by both light and electron microscopy, revealed the following findings: general loss of vascular endothelium and pericytes with subsequent mural disorganization and loss of the blood-retinal barrier.



Medical Care:
  • The treatment strategy generally depends on the extent of the disease advancement at the time of presentation.
  • Patients may be monitored by conservative observation if the disease is limited and does not threaten macular vision.
  • Development of macular exudate prompts definitive treatment intervention.

Surgical Care:

  • For uncomplicated disease, scattered laser photocoagulation under slit lamp biomicroscopy is used for the posterior area disease. Indirect ophthalmoscope mounted laser or cryotherapy is used for more peripheral or anterior area disease. Complete treatment may require several sessions and to abnormal vessels or areas of nonperfusion.
  • The most extensive clinical laser experience has been with argon blue-green laser, although there is heightened interest in argon green or the yellow wavelengths of the dye laser. The latter two types emit wavelengths that are better absorbed by hemoglobin. Xenon arc photocoagulation has been used in cases.
  • When the disease is complicated by exudative retinal detachment, cryotherapy applied directly to the abnormal vasculature is recommended. This usually involves a freeze-refreeze technique. Draining associated subretinal fluid to facilitate adequate freezing of the retina may be necessary.
  • In some cases, vitreous surgery, consisting of membranectomy and endolaser ablation of leaking vessels, was used to eliminate tractional detachment.
  • One series evaluated 292 eyes with Coats' disease in which 197 eyes received either photocoagulation or cryotherapy diathermy (13.6%) or retinal detachment surgery (6.3%).
    • Complete scarring of the lesions with resorption of exudates occurred in 52.1% of overall cases and in 67.3% of patients with no retinal detachment.
    • The final visual acuity was less than 20/400 in 45.3% of patients, from 20/200 to 20/30 in 39.4% of patients, and better than 20/30 in 15.3% of patients.

Consultations:

  • Prompt consultation with the vitreoretinal service is recommended.
  • Consult with the internist to exclude other systemic problems that may present with similar eye findings.

Activity: Allow activity as tolerated or as recommended by the vitreoretinal service.

Bibliography:

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  • Boynton JR, Purnell EW: Bilateral microphthalmos without microcornea associated with unusual papillomacular retinal folds and high hyperopia. Am J Ophthalmol 1975 May; 79(5): 820-6[Medline].
  • Burch JV, Leveille AS, Morse PH: Ichthyosis hystrix (epidermal nevus syndrome) and Coats' disease. Am J Ophthalmol 1980 Jan; 89(1): 25-30[Medline].
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  • Duke JR, Woods AC: Coats' disease II. Studies on the identity of the lipids concerned, and the probable role of mucopolysaccharides in it pathogenesis. Br J Ophthalmol. 1963; 47: 413.
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  • Fogle JA, Welch RB, Green WR: Retinitis pigmentosa and exudative vasculopathy. Arch Ophthalmol 1978 Apr; 96(4): 696-702[Medline].
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  • Plager DA, Orgel IK, Ellis FD, et al: X-linked recessive familial exudative vitreoretinopathy. Am J Ophthalmol 1992 Aug 15; 114(2): 145-8[Medline].
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  • Schuman JS, Lieberman KV, Friedman AH, et al: Senior-Loken syndrome (familial renal-retinal dystrophy) and Coats' disease. Am J Ophthalmol 1985 Dec 15; 100(6): 822-7[Medline].
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NOTE:
Medicine is a constantly changing science and not all therapies are clearly established. New research changes drug and treatment therapies daily. The authors, editors, and publisher of this article have used their best efforts to provide information that is up-to-date and accurate and is generally accepted within medical standards at the time of publication. However, as medical science is constantly changing and human error is always possible, the authors, editors, and publisher or any other party involved with the publication of this article do not warrant the information in this article is accurate or complete, nor are they responsible for omissions or errors in the article or for the results of using this information. The reader should confirm the information in this article from other sources prior to use. In particular, all drug doses, indications, and contraindications should be confirmed in the package insert.

AUTHOR INFORMATION
Godwin S Okoye, MD, PhD, is a member of the following medical societies: American Academy of Emergency Medicine, and American Academy of Ophthalmology
Editor(s): Andrew Lawton, MD, Medical Director of Neuro-Ophthalmology Service, Section of Ophthalmology, Baptist Eye Center, Baptist Health Medical Center; Donald S Fong, MD, MPH, Assistant Clinical Professor of Ophthalmology, UCLA School of Medicine; Consulting Physician, Department of Ophthalmology, Southern California Permamente Medical Group; Steve Charles, MD, Director of Charles Retina Institute; Clinical Professor, Department of Ophthalmology, University of Tennessee College of Medicine; Lance L Brown, OD, MD, Ophthalmologist, Regional Eye Center, Affiliated With Freeman Hospital and St John's Hospital, Joplin, Missouri; and Hampton Roy, Sr, MD, Clinical Associate Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences


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