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Anterior Segment Uveitis Viral Aetiology in Anterior Uveitis – The Tip of an Iceberg? Dicle Hazirolan 1 and Uwe Pleyer 2 1. Senior Resident, Ankara Training and Research Hospital, Ministry of Health, Department of Ophthalmology, Ankara, Turkey; 2. Professor, Department of Ophthalmology, Charité Hospital, Charité Campus Virchow-Klinikum, Humboldt University, Berlin, Germany Abstract Identification of an infectious cause in intraocular inflammation is of crucial importance since their treatment and prognosis differ from non-infectious aetiologies. Herpes simplex and varicella-zoster viruses are well known causes of anterior uveitis. Furthermore, cytomegalovirus (CMV) and rubella virus (RV) are also detected in a significant number of patients. Despite their different aetiology, viral anterior uveitis may have similar features and often presents with unilateral diffuse, fine, stellate keratic precipitates, iris atrophy or ocular hypertension. Viruses are increasingly recognised as aetiology of anterior uveitis that has previously been referred as idiopathic. RV, for example, causes a distinct clinical spectrum of ocular signs and symptoms presenting as Fuch’s uveitis syndrome (FUS) in Europe, strongly suggesting a role in its pathogenesis. Interestingly, CMV may also be involved in the pathogenesis of both FUS and Posner–Schlossman syndrome in particular in the Asian population. Keywords Anterior uveitis, cytomegalovirus, Fuch’s uveitis syndrome, herpes simplex virus, Posner–Schlossman syndrome, rubella virus, varicella-zoster virus Disclosure: The authors have no conflicts of interest to declare. Received: 16 December 2011 Accepted: 1 February 2012 Citation: European Ophthalmic Review, 2012;6(2):119–24 Correspondence: Dicle Hazirolan, Eryaman 2, Etap, Demire A1-1 Blok, No:54, Ankara, Turkey. E: dicleoncel@hotmail.com Intraocular viral infections have various presentations. They may be detected as anterior uveitis, intermediate uveitis, acute retinal necrosis (ARN), progressive outer retinal necrosis (PORN) and neuroretinitis (see Figure 1). 1,2 Anterior uveitis (AU) in most patients is either idiopathic or associated with HLA-B27 positivity. However, a viral cause of AU is often underestimated. The most common viruses in the aetiology of viral AU (VAU) are herpes simplex virus (HSV), varicella-zoster virus (VZV), cytomegalovirus (CMV) and rubella virus (RV). 1–3 Recently, the aetiology of some ‘idiopathic’ AU syndromes are proved to be viral. RV and CMV, for example, cause a distinct clinical spectrum of ocular symptoms presenting as Fuch’s Uveitis syndrome (FUS) which strongly suggest that they might be involved in the pathogenesis of FUS. 4,5 Interestingly, CMV may also be involved in the pathogenesis of Posner-Schlossman syndrome (PSS). 4,6 Diagnosis of VAU depends mostly on clinical findings. The clinical features commonly described in association with VAU include diffuse, fine, stellate or dendritiform keratic precipitates, ocular hypertension and iris atrophy. 4,5,7–14 Although clinical features of different VAUs overlap, there are some characteristic findings depending on the causative viral agent. In this review, the clinical features of the most common VAUs (HSV, VZV, CMV and RV) are presented. © TOUCH BRIEFINGS 2012 Herpes Viridae Family (Herpes Simplex Virus, Varicella-zoster Virus, Cytomegalovirus) These DNA viruses are ubiquitous and following primary infection, lifelong latency is a characteristic feature. The three main viruses responsible for ocular inflammation are HSV-1, VZV and CMV. Epstein-Barr virus (EBV) and HSV-2 have also infrequently been detected in ocular disease. 15 The worldwide seroconversion to herpes viruses ranges from 60 to 90 %. 16–21 VAU, due to either HSV or VZV is reported to be 5 to 10 % of all uveitis cases. 22,23 However, other viruses such as CMV and RV are also increasingly being implicated as causative factors, particularly in patients presenting with hypertensive AU. 4,5,7–11 Interestingly, the clinical features of herpetic ocular infection depend to a certain extent on the immune status of the patient. CMV infection, for example, predominantly manifests as retinitis in immunocompromised patients. 24,25 In contrast, it almost always occurs as AU in otherwise healthy immunocompetent patients. 24,25 Similarly, in VZV infection, posterior segment involvement is more likely to occur in immunocompromised patients and they are also more likely to develop chronic disease. 26 Herpes Simplex Virus and Varicella Zoster Virus These two herpes viruses share certain common features in their manifestations and treatment. Frequently, uveal inflammation associated with herpes viruses evolves as keratoiritis associated to corneal disease (see Figure 2). However, HSV associated AU may also 119