Giant cell arteritis (GCA), also known as temporal arteritis, is one of the most common systemic granulomatous vasculitides of the elderly [1, 2]. GCA affects large- and medium-sized arteries, especially the superficial temporal, occipital, vertebral, ophthalmic, posterior ciliary, internal and external carotid arteries [3]. The involved arteries develop intimal hyperplasia and luminal obstruction, thereby leading to ischemic manifestations and associated symptoms such as headache, scalp tenderness, jaw claudication, malaise, fever, and vision loss [4]. Elevated systemic inflammatory markers such as erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and interleukin-6 can be seen in the acute phase. Despite the associated suggestive symptoms and abnormal laboratory tests, temporal artery biopsy is widely accepted as the gold standard for the diagnosis of GCA [2].

GCA is the most frequent primary vasculitis affecting people aged over 50 years [5]. The overall incidence of GCA in people over age 50 varies from 1.1 per 100,000/year to 32.4 per 100,000/year, while European countries have the highest incidence [6]. The incidence of GCA increases with age, from 2.3 per 100,000/year among people in their sixth decade to 44.7 per 100,000/year in their ninth decade and older [7, 8]. The incidence in women is nearly twice that of men [5].

The exact etiology of GCA is unclear with a variety of infectious agents such as herpes and parainfluenza viruses as possible disease triggers [9, 10]. A genetic predisposition has also been recognized as an important component as GCA is associated with carriage of HLA-DRB1*04 alleles [11].

The most common ocular manifestation of GCA is anterior ischemic optic neuropathy (AION) caused by interruption of blood flow in the posterior ciliary arteries. AION caused by GCA is responsible for 78–99 % of vision loss [12, 13]. Amaurosis fugax, due to the ischemia of outer retinal segment, has an incidence of 2–30 % in patients with GCA. GCA can also induce ischemia of the oculomotor nerves or the extraocular muscles resulting in diplopia.

Uveitis is an uncommon manifestation of GCA. At the time of this publication, there are only a few case reports in the last 20 years [1, 14–17]. Ischemia of the posterior ciliary arteries and their branches can cause posterior uveitis. Choroidal ischemic lesions, which appear as peripheral chorioretinal degenerative patches, can be seen after the onset of posterior uveitis [18]. The degenerative patches have a triangular pattern with base toward the periphery and apex toward the posterior pole [18]. Vitritis and exudative retinal detachment have also been reported in posterior uveitis associated with GCA [1]. In addition, disc edema, multiple raised creamy subretinal peripapillary lesions, narrowed arterial vessels of the posterior pole, sheathing and cotton wool spots have been observed in the fundus examination [14]. The fluorescein angiography (FA) can also reveal segmental disc hyperfluorescence and signs of arterial vasculitis in the posterior pole [14].

Anterior uveitis can be caused by ischemia of anterior segment. Corneal edema, keratic precipitates, anterior chamber and vitreous cells have also been reported as associated manifestations of anterior uveitis [15, 18]. Pan uveitis can also occur due to the ischemia of both anterior and posterior segments and usually associated with optic nerve ischemia [18].

Elevation of ESR is commonly seen in GCA but is neither a sensitive nor specific indicator. The false negative rate can be as high 17 % in diagnostic cases, thus normal ESR cannot exclude GCA [19]. C reactive protein (CRP) is an indicator of acute inflammation with high specificity of 97.5 %. CRP is more sensitive than ESR and can be elevated even when ESR level is normal. Combining CRP and ESR together, the test sensitivity can be increased to 99 % [20].

Elevated platelet count, greater than 400 × 10³/L, is a specific marker in the diagnosis of GCA [21]. Thrombocytosis has been positively correlated with biopsy proven GCA [22, 23]. In addition, serum interleukin-6 (IL-6) has been elevated in patients with GCA [24].

Temporal artery biopsy is generally recommended as the gold standard for the diagnosis of GCA. Biopsy should be performed once the diagnosis of GCA is suspected. The overall sensitivity of temporal artery biopsy is 87 %. Contralateral biopsy should be performed if the initial biopsy is negative in highly suspected cases [25]. The recommended timing of the biopsy is within the first two weeks after presentation as patients are treated with steroids which could reduce the inflammation in the artery and thus make the diagnosis of GCA more difficult [26].

The diagnosis of GCA depends on at least three of the following five criteria: (1) age at onset of 50 years or older, (2) onset of new headache, (3) temporal artery tenderness or decreased pulse, (4) elevated ESR (≥50 mm/h) by the Westergren method, and (5) histologic findings, according to the American College of Rheumatology (ACR) classification in 1990 [27].

However, the ACR criteria have limitations in that 28.3 % of patients met ACR criteria but had a negative biopsy [28]. One possible explanation is that the predictive values of ACR criteria could decrease when disease prevalence is low, especially in ophthalmology or general medical clinics [29].

The goal of treatment in GCA is to stop the vascular inflammation and prevent the progression of ischemia. There are multiple medications that have demonstrated efficacy:

Systemic corticosteroids are the first choice for treatment in GCA due to the rapid onset of anti-inflammatory effects. There is no generally accepted dose of corticosteroids. Some physicians recommend starting oral prednisolone 1 mg/kg up to a maximum of 80 mg daily, while others initiate treatment with intravenous methylprednisolone 1 g/daily for the first three days followed by PO Prednisone. Both treatment strategies include oral prednisone 1 mg/kg for at least one month and then subsequently tapering based on symptoms and inflammatory markers [30]. Generally, systemic symptoms improve within the first 24–72 h of steroid treatment, while ESR normalizes several weeks later [30]. It has been reported that progressive visual loss may occur despite the early administration of high-dose corticosteroids [30, 31]. Topical and/or local corticosteroids can also be used in those who develop uveitis from GCA.

Methotrexate has been used as adjunct to systemic corticosteroids in several studies. Methotrexate may reduce the relapse rate and the dose of steroids as a steroid-sparing co-medication in a meta-analysis of three randomized controlled studies [32]. Treatment with methotrexate is recommended by European League Against Rheumatism (EULAR) [33]. However, a four year clinical trial showed no beneficial effect when standard therapy with prednisone was combined with methotrexate [34].

Infliximab, a tumor necrosis factor-alpha antibody, has demonstrated no beneficial effect in GCA and may potentially be detrimental in a randomized controlled trial [35]. Conversely, tocilizumab, a humanized antihuman IL-6 receptor antibody, has demonstrated the ability to reduce the dose of corticosteroids, thus reducing the incidence of corticosteroids-associated adverse events [24].