Clinical photo of the right eye nasal peripheral retina with retinal hemorrhage and retinal infiltrates
Clinical photo of the right macula showing characteristic presentation of cytomegalovirus retinitis in the macula with a “cheese on ketchup” appearance
(a) Fundus photo of the posterior pole showing retinitis and adjacent flame-shaped retinal hemorrhage. (b) Corresponding cross-sectional image on optical coherence tomography showed retinal thickening with small amount of subretinal fluid at the fovea (courtesy of Prof Koh-Hei Sonoda)
Fundus photo showing cytomegalovirus retinitis with foci in both the macula and the area nasal to the disc (courtesy of Prof Koh-Hei Sonoda)
(a) Typical presentation of cytomegalovirus retinitis with abundant retinal hemorrhage and infiltrate resembling the “cheese on ketchup” appearance. (b) Picture of the same patient following treatment showing resolution of the retinitis and the associated hemorrhage (courtesy of Dr. Jay Chhablani)
(a) Fundus photo showing a diffusely involved macula with retinitis and retinal hemorrhage. (b) Corresponding optical coherence tomography showing thickened retina in an area with cytomegalovirus retinitis (courtesy of Prof Koh-Hei Sonoda)
Fundus photo demonstrating the “granular” appearance of retinal infiltrate in the periphery (courtesy of Prof Koh-Hei Sonoda)
Fundus photo demonstrating the “granular” appearance of retinal infiltrate in the periphery
(a) Peripapillary vessels with sheathing, resembling the classic description of “frosted branch angiitis.” (b) Corresponding fluorescein angiogram showing the staining of involved blood vessel relative hypofluorescence in areas with dense retinal infiltrate (courtesy of Dr. De-Kuang Hwang)
Showing staining and leakage on fluorescein angiogram in the affected areas in a patient with cytomegalovirus retinitis
(a, b) Cytomegalovirus retinitis patient with retinal thickening and intraretinal cystic changes demonstrated by optical coherence tomography. (c) Corresponding optical coherence tomography angiogram showed non-perfusion in areas of active retinitis (courtesy of Dr. Jay Chhablani)
Optical coherence tomography showing thickened retina in an area with cytomegalovirus retinitis (courtesy of Dr. De-Kuang Hwang)
It was believed that when CMV retinitis occurs in an AIDS patient, there is minimal or no inflammatory response. This was thought to be related to the lack of an active immunity in the host to mount such as response in reaction to the infective process. However, there have been reports to suggest that vitritis and anterior uveitis occur more commonly than expected and may be related to the widespread destruction of the retina in severely affected patients.
As the retinitis progresses, areas left behind may show atrophic retina with sclerotic vessels. In the pre-HAART era, the incidence of retinal detachment in patients with CMV retinitis was around 33% per eye per year (Jabs et al. 1989; Gross et al. 1990; Kempen et al. 2001, 2003; Freeman et al. 1993). These detachments were associated with multiple retinal atrophic holes in areas of healed retinitis in the periphery (Freeman et al. 1992). Breaks form from necrotic areas which have been affected by the retinitis. These seldom present in the acute stage of the retinitis; rather, they usually present late, from weeks to months after initiation of anti-CMV treatment. It has been reported that the median time for retinal detachment to occur in an eye previously suffering from CMV retinitis was 18.2 months (Freeman et al. 1993). Risk factors for the development of retinal detachment include severe peripheral retinitis, severity of the retinitis when it was active, and involvement of the vitreous base by the disease (Freeman et al. 1993; Kempen et al. 2001; Holland et al. 1989). Fortunately, following the introduction of HAART, the risk of detachment from CMV retinitis has been much reduced (Kempen et al. 2001; Martin et al. 1994; Freeman 1999).
Immune recovery uveitis can occur following successful treatment of the underlying condition by HAART. This is thought to be a result of immune reconstitution in the host. The risk has been reported to be from 15.5% to 37.5% (Jabs et al. 2002; Arevalo et al. 2003). Clinical signs include iritis, vitritis, macular edema, and epiretinal membrane formation (Whitcup 2000; Karavellas et al. 2000; Newsom et al. 1998). Patients may suffer visual loss because of macular edema, hazy media due to vitritis, and cataract formation.
Diagnosis
Diagnosis of CMV retinitis should be made based on clinical grounds. However, laboratory tests can aid the diagnosis in uncertain cases. It should be noted that in any patients with HIV of AIDS, especially those that have a CD4 cell count below 50/mm3 (Kuppermann et al. 1993) that presents with retinal hemorrhage and retinitis, CMV retinitis should always be on the top of the differential list.
Blood CMV antigenemia may not be the most accurate test to correlate with ocular CMV retinitis. In this regard, polymerase chain reaction (PCR) tests for CMV on aqueous samples have a higher accuracy. In a recent study, PCR of the aqueous yielded significantly higher positive rates than testing for blood CMV antigenemia (Iu et al. 2016). Aqueous samples could easily be taken at the time of intravitreal injection of anti-CMV drugs when a paracentesis is performed into the anterior chamber. Alternatively, this could also be done at the slit lamp as a diagnostic procedure under aseptic conditions. Generally, the number of CMV DNA in aqueous by using real-time PCR is regarded as positive if it is above 500 copies/mL. In addition, as PCR is ultrasensitive in amplifying even only a trace amount of DNA, any procedural errors during PCR may lead to significant changes in terms of the results. Hence, the concentration of interleukin-8 (IL-8) in the aqueous is also another recommended marker for clinical diagnosis and monitoring. It can be safely performed by cytometric bead array (CBA) with flow cytometry on the aqueous aspirated during anterior chamber paracentesis at the time of intravitreal injections. It has been shown to be a good quantitative laboratory indicator of the activity of intraocular inflammation caused by CMV retinitis (Wang et al. 2014).
Management
Treatment of CMV retinitis in AIDS patients should be divided into ocular and systemic treatments. The United States Food and Drug Administration (FDA)-approved anti-CMV agents include ganciclovir, valganciclovir, foscarnet, and cidofovir. Intravenous ganciclovir is administered every 12 hours at a dose of 5 mg/kg for 2 weeks during induction phase and 5 mg/kg daily as maintenance (Au Eong et al. 1999; Stewart 2010). Ocular treatment is most commonly in the form of intravitreal injections, which has the advantage of delivering the drug to the site of infection without causing systemic side effects. Disadvantages include the risk of intravitreal injections, the need for multiple injections, and also the inability to provide coverage for the contralateral eye and systemic viremia. Weekly intravitreal injections are performed initially, at a dose of 200 μg/0.05 mL (Henry et al. 1987; Miao et al. 2013; Wang et al. 2014). The aqueous levels of CMV DNA and IL-8 aid the clinician to decide the timing of cessation of intravitreal injections of antiviral agents. Foscarnet (2400 μg/0.1 mL) may be considered if the intraocular CMV DNA in the aqueous is persistently positive, and interleukin-8 increases after intravitreal injection of ganciclovir, as resistance to ganciclovir is a possibility (Boss et al. 2016; Lieberman et al. 1994). Systemic treatment has the advantages of providing coverage for CMV viremia and also protection for the contralateral eye, but patients may suffer from undesirable side effects; common ones include bone marrow suppression with ganciclovir, nephrotoxicity with foscarnet.
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