Fig. 6.1
(a) Fundus photograph of the left eye of a patient with cat-scratch disease shows optic disc edema with telangiectasis, a complete macular star, and a peripapillary serous retinal detachment. (b) Late-phase fluorescein angiogram shows optic disc hyperfluorescence with a normal macula. (c) Spectral domain optical coherence tomography shows macular serous detachment with cystoid macular edema
Neuroretinitis usually has a self-limited course, with most patients recovering good visual acuity over a period of several weeks [19]. The macular star usually resolves in approximately 2 to 3 months, but it may be present for up to 1 year. A few patients may be left with mild pallor of the optic disc [24]. Retinal pigment epithelium changes also may develop after a resolution of a prominent macular star.
CSD may occasionally present with a large inflammatory mass or exudate of the optic nerve head [25].
Unifocal or multifocal white areas of inner retinitis or chorioretinitis, of 50–100 microns, typically juxtavascular in location, may accompany neuroretinitis or occur in the absence of obvious optic disc involvement [7, 19, 26–28] (Fig. 6.2). Such retinal lesions were found to be more common than neuroretinitis by some authors [27] (Fig. 6.3).
Fig. 6.2
(a) Fundus autofluorescence of the left eye of a patient with neuroretinitis related to cat-scratch disease shows peripapillary hypoautofluorescence and hypoautofluorescent striae in the macular area. (b) Optical coherence tomography shows peripapillary serous detachment with intraretinal macular hyperreflective dots related to macular hard exudates
Fig. 6.3
Fundus photographs of a patient with cat-scratch disease show bilateral small retinal infiltrates without associated neuroretinitis
Branch retinal arteriolar occlusion [24, 26, 27, 29, 30] may be associated with an area of focal retinitis. A case of central retinal artery and vein occlusion has been reported [31].
Less common chorioretinal manifestations of CSD include large inflammatory retinal mass in the posterior pole [25], subretinal mass with or without associated abnormal vascular network [32], intermediate uveitis with retinal vasculitis[33], unilateral panuveitis with clinical and fluorescein angiographic features simulating Vogt-Koyanagi-Harada disease [34], isolated serous macular detachment [35], serous macular detachment simulating central serous chorioretinopathy [36], macular hole [37, 38], and vitreous hemorrhage [39].
Due to the relationship between Bartonella and vascular endothelium, chorioretinal vasoproliferative lesions are observed, which are more commonly found in immunosuppressed patients despite not being exclusive [31, 32].
6.5 Diagnosis
The diagnosis of CSD is based on epidemiological data, medical history, serology, polymerase chain reaction, and pathology. Despite the use of various data in diagnosing the disease, in practice it is the positive blood test that is considered as the decisive diagnostic information.
The epidemiological history is fundamental when diagnosis is suspected; therefore close contact with domestic animals is of prime significance. In a study conducted with patients with intraocular lesions of CSD, 100 % of the patients confirmed contact with a cat and roughly 65 % remembered having been scratched. In relation to the medical history, in a recent study, it was found that approximately 65 % of the patients with the ocular disease manifested some kind of systemic symptoms, findings also reported by Curi et al. [7].
Serology is the gold standard for diagnosis, with IgG for B. henselae positive indicating previous contact with the bacteria. In a population study, approximately 10 % of healthy individuals tested positive for Bartonella (IgG) [40, 41]. Recent or acute infection is diagnosed by IgG titers of greater than 1:256.
6.6 Differential Diagnosis
Differential diagnosis of retinitis and chorioretinitis associated with CSD includes toxoplasmosis retinochoroiditis, syphilis, rickettsiosis, Lyme disease, chikungunya, and Behçet disease.
Causes of neuroretinitis such as tuberculosis, sarcoidosis, toxoplasmosis, syphilis, varicella, herpes simplex, diffuse unilateral subacute neuroretinitis (DUSN), leptospirosis, and recurrent idiopathic neuroretinitis should always be considered as differential diagnosis of Bartonella neuroretinitis. Noninflammatory conditions that cause optic disc edema and macular star are also included in the differential diagnosis including diabetes, systemic hypertension, branch retinal vein occlusion, and anterior ischemic optic neuropathy [44].
6.7 Management
Treatment of the ocular disease is still a subject of debate. Older works described CSD as a self-limited condition, but some benefits of antibiotic use have been observed.
Curi et al. found a significant number of patients with accentuated loss of visual acuity in presentation who showed improvement after antibiotic treatment.
Currently antibiotics are recommended to treat the secondary ocular symptoms of CSD: doxycycline100mg every 12 hours for 1 month. Other antibiotics have also been used with good response such as ciprofloxacin, azithromycin, rifampin, and trimethoprim-sulfamethoxazole [47]. In case of severe infection, doxycycline may be given intravenously or used in combination with rifampin, 300 mg orally twice daily. Children with CSD may be treated with azithromycin.
Among immunocompromised individuals, treatment is extended for 4 months [3]. In HIV seropositive patients, this timeframe is unknown, as relapse is possible after suspension of the antibiotic treatment. The CD4 count might be an important factor in the decision-making as regards the suspension of medication. Therefore, it is suggested that medication only be suspended when the CD4 count has increased, as occurs in other opportunist ocular diseases, such as cytomegalovirus retinitis and toxoplasmic retinochoroiditis.
Paradoxical response to treatment has been reported in ocular bartonellosis [48].
The role of systemic steroids in CSD is unknown and still debatable [49].
Prevention of CSD includes wash and disinfection of any wounds immediately after a cat scratch or bite and avoids contact with stray felines.
6.8 Prognosis
The prognosis of systemic disease is usually good in immunocompetent patients. In immunocompromised patients, even complications, prognosis is good provided appropriate and timely treatment [1, 3].
The prognosis of ocular disease is usually good with complete recovery of visual acuity in most patients. Few patients keep complaining of visual field loss for many months. In patients with neuroretinitis, macular exudates may take months to resolve. A few patients may be left with optic disc pallor or atrophy [24].
Core Messages
Cat-scratch disease is a self-limited systemic illness caused by a gram-negative bacillus, Bartonella henselae, and characterized by regional lymphadenopathy with associated febrile illness.
Neuroretinitis is the most typical ocular manifestation of cat-scratch disease, but an array of other ocular changes may occur including Parinaud’s oculoglandular syndrome, retinitis, chorioretinitis, and vascular changes.
Diagnosis is primarily based on clinical findings and confirmed by serology and/or PCR.
Treatment is based on antibiotics, mainly doxycycline.
