Eales disease (ORPHA:40923)
A rare ophthalmic disorder characterized by 3 stages: vasculitis, occlusion, and retinal neovascularization, leading to recurrent vitreous hemorrhages and vision loss.
Epidemiology
The prevalence is unknown. The disorder has been reported worldwide but is more commonly observed in the Indian subcontinent where the estimated annual incidence is 1/135-1/200 ophthalmic patients. Males are predominantly affected. Of late, the disease incidence seems to be reducing.
Clinical description
The predominant age of onset is 20-30 years (earlier in Asians). The disorder can appear in adolescence. Eales disease (ED) is characterized by 3 sequential vascular responses that determine the course of the disease: inflammation (peripheral retinal perivasculitis); occlusion (peripheral retinal capillary non-perfusion); and neovascularisation of the retina or disk, which often leads to vitreous hemorrhage. The first 2 stages are generally asymptomatic while vitreous hemorrhage (often sudden and unilateral) is characterized by small specks, floaters, ''cobwebs'' and a decrease in visual acuity (often remission). The fellow eye is affected in 50-90% of cases after a gap of 3-10 years. Recurrences are common. Recurrent bleeds result in tractional retinal detachments, retinal tears, and epimacular membranes. Others may show a mild reduction of vision associated with retinal vasculitis (without vitreous hemorrhage). In addition, headache, variation in peripheral circulation, dyspepsia, chronic constipation, and epistaxis have also been associated with ED. Saxena and Kumar classification is based on visual outcomes and is as follows: Stage 1: periphlebitis of small (1a) and large (1b) calibre vessels with superficial retinal hemorrhages; Stage 2a: capillary non-perfusion, 2b: neovascularization elsewhere/of the disc; Stage 3a: fibrovascular proliferation, 3b: vitreous hemorrhage; Stage 4a: traction/combined rhegmatogenous retinal detachment and 4b: rubeosis iridis, neovascular glaucoma, complicated cataract and optic atrophy.
Etiology
The etiology of ED remains elusive; Several immunological, molecular biological, and biochemical studies have indicated the roles of human leukocyte antigen, retinal S-antigen autoimmunity, Mycobacterium tuberculosis genome, free radical damage, and hyperhomocysteinemia in the pathogenesis of Eales disease. An increase of peptide growth factors like platelet-derived growth factor, insulin-like growth factor, epidermal growth factor, transforming growth factors alpha and bêta, vascular endothelial growth factor, urokinase, metalloprotease enzymes, and a 88 kDa protein has been reported.
Diagnostic methods
Diagnosis is based on fundus fluorescein angiography (FFA) findings that may show early changes such as periphlebitis, vascular sheathing or peripheral nonperfusion and neovascularization. Wide field angiography is useful for the detection of peripheral lesions in the retina. Ultrasonography is needed to rule out associated retinal detachment and ocular coherence tomography (OCT) offers high-resolution imaging of the retina.
Differential diagnosis
Differential diagnosis includes retinopathy of prematurity (ROP) sequelae, familial exudative vitreoretinopathy, sarcoidosis, Behçet disease, sickle cell anemia, Terson syndrome, posttraumatic vitreous hemorrhage, juvenile diabetes and primary branch retinal vein occlusion.
Management and treatment
Management is symptomatic and depends on the stage of the disease. It includes periodic assessment (in the regressed stage of periphlebitis or fresh vitreous hemorrhage), steroids (periocular injections or systemic) and antitubercular drugs (in the active perivasculitis stage). Laser photocoagulation is used in case of neovascularisation of retina or gross capillary nonperfusion. Vitreous surgery is indicated in non-resolving vitreous hemorrhage (usually > 3 months). Intravitreal anti-VEGF therapy is currently being tested as a definitive therapy for ED.
Prognosis
Isolated episodes of vitreous hemorrhage usually settle down without visual deficit. However, some patients may lose vision significantly due to recurrent episodes of vitreous hemorrhage, macular changes, and tractional or combined retinal detachment involving the macula. Blindness due to ED is rare. There is no known mortality associated with the disease.

                            Last update: 
                            December 2019


                            - Expert reviewer(s): 
                            Dr Pukhraj RISHI