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Viral retinitis is a rare disease that implies involvement of Herpesviridae, a family of double-stranded DNA viruses characterized by latency within the host’s cells after the primary infection, according to J. Fernando Arevalo, MD, PhD, FACS.
Dr. Arevalo is the Edmund F. and Virginia Ball professor of ophthalmology, and chairman of ophthalmology, Johns Hopkins Bayview Medical Center, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore.
The viruses implicated include herpes simplex virus (HSV), varicella zoster virus (VZV), herpes zoster viruses, cytomegalovirus (CMV), and perhaps Epstein Barr virus.
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The CMV retinitis virus is the most frequently occurring ocular opportunistic infection in patients with AIDS. Before the advent of combination antiretroviral therapy, CMV retinitis developed in 30% of these patients and afterward in less than 1%.
Patients with AIDS are not the only group in which CMV retinitis can occur. Others include neonates and those in whom immunosuppression was induced, such as after organ transplantation, hematopoietic stem cell transplantation, malignancy, or other causes, Dr. Arevalo noted.
When these patients present, optical coherence tomography can be used to diagnose atrophic retinal detachments resulting from the very thin retinal tissue and exudative retinal detachments in the macula, he advised.
Polymerase chaine reaction
According to Dr Arevalo, polymerase chain reaction (PCR) can be performed to diagnose the CMV retinitis; while 50- to 100-Î¼l tissue samples are ideal, the disease can be diagnosed with as little as 1 Î¼l of tissue.
Once diagnosed, CMV retinitis can be treated with intravenous ganciclovir (5 mg/kg every 12 hours for two weeks and 5 mg/kg/day for maintenance) or oral valganciclovir (Valcyte, Genentech) (induction dose, 900 mg twice daily for three weeks and 900 mg once daily for maintenance). Intravitreal antiviral drug implants for CMV retinitis include ganciclovir (2-5 mg/0.05-0.1 Î¼l) and foscarnet (Foscavir, Pfizer) (2.4 mg/0.1 Î¼l).
According to Dr. Arevalo, retinal detachments develop in about 20% of this patient population. This detachment rate may decrease with improved therapies.
The number of patients in whom CMV retinitis develops has decreased, which, in turn, decreases the number of retinal detachments.
He noted that the extent and activity of the retinitis are risk factors for detachment. It is imperative to monitor this in patients and prepare a treatment plan.
“With longer patient survival, the need is great for a surgical strategy that will provide the best long-term visual outcome,” he said.
Silicone oil injection
Vitrectomy with silicone oil (SO) injection and oil removal are the mainstays of therapy for retinal detachment.
Other approaches such as buckles, vitrectomy with gas tamponade, and laser demarcation may also provide excellent visual and anatomic results for retinal detachments, Dr., Arevalo explained.
“The choice of the best surgical option depends on the mechanical factors of the detachment as well as patient factors, such as their immune status, expected survival, control of the retinitis, and their visual needs,” Dr. Arevalo said.
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Phacoemulsification and implantation of intraocular lenses are options for treating cataracts that develop and can be performed at the same time the SO is removed.
Immune recovery uveitis can occur in patients with AIDS who develop CMV retinitis. Dr. Arevalo reported that in his series of patients, various pathologies were observed: vitritis, papillitis, macular edema, extensive gliosis, anterior uveitis, cataract, proliferative vitreoretinopathy (PVR) with retinal detachment, and extensive macular edema and an exudative detachment with a macular hole.
Acute retubak necrosis
This pathology is the result of HSV-2 in younger adults and HSV-1 or VZV in older adults.
“Immunocompetence is the traditional hallmark of ARN, but recent studies have reported immune dysfunction resulting from medications, malignancy, and other systemic disorders in up to 50% of patients,” Dr. Arevalo explained.
The severe inflammatory reaction that characterizes ARN causes irreversible destruction of retinal and optic nerve tissue. Visual loss in the affected eye and fellow eye can be prevented with anti-inflammatory therapy combined with antiviral treatment.
The initial treatments include the antivirals acyclovir (10 mg/k/IV three times daily, valacyclovir (2 grams three times daily) for HSV-ARN; and for VZV-ARN 15 mg/k/IV three times daily and 2 grams four times daily, respectively.
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The oral anti-inflammatory prednisolone can be administered for HSV-ARN (30 mg/day) and for VZV-ARN (40-60 mg/day).
The intravitreal antiviral foscarnet can be used to treat HSV-ARN and VZV-ARN (2.4 mg/0.1 milliliter for both).
The topical drugs prednisolone acetate (Pred Forte 1%) and cyclopentolate (Cyclogyl 0.1%) are administered, respectively, 1 drop four times daily for both HSV-ARN and VZV-ARN and 1 drop twice daily for both pathologies.
Dr. Arevalo noted that he begins with initially higher doses for VZV-ARN and once the PCR results confirm the presence of HSV-ARN, he lowers the doses.
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Retinal detachments also occur in patients with ARN in 50% to 75% of untreated eyes, within one to two months after the ARN symptoms appear.
Dr. Arevalo also warned that vitreous inflammation can lead to vitreous organization and PVR with a subsequent tractional retinal detachment.
Treatment for ARN could involve a prophylactic vitreous surgery in patients with poor or nonresponsive retinal lesions, especially those near the posterior pole. Dr. Arevalo pointed out that vitreous surgery is indicated for patients with rhegmatogenous retinal detachments, a late-stage complication.
“We have had several cases that were resistant to medical therapy but had dramatic improvement of the retinal necrosis lesions immediately after the vitreous surgery, as a result of the removal of the inflammatory cytokines,” he said.
Research has found that SO tamponade has a positive impact on retinal layers thickness and visual acuity in patients who underwent pars plana vitrectomy for rhegmatogenous retinal detachment.
SO tamponade is viewed as ideal for retinal detachments, Dr. Arevalo explained, but only for the short term.
Finally, endolaser photocoagulation is applied in two or three rows during vitrectomy to normal retinal tissue to surround the posterior edge of the necrotic lesions, he explained.
“SO surgery is the preferred surgical approach with oil removal months later during phacoemulsification,” Dr. Arevalo said. “Vitrectomy with gas tamponade, scleral buckle, and laser demarcation follow in that order of preference.”
Dr. Arevalo concluded that achieving surgical success requires the permanent closure of retinal holes and relaxation of vitreous traction that might cause new tears.
“Pars plana vitrectomy with SO injection obviously accomplishes these objectives; even failed cases with open inferior breaks will have the retinal detachment sufficiently demarcated that the macula remains attached,” he said. “If good adhesion is achieved, oil removal can be considered at a later date in combination with phacoemulsification.”
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J. Fernando Arevalo, MD, PhD, FACS
This article is based on Dr. Arevalo's presentation at the American Academy of Ophthalmology 2019 annual meeting. Dr. Arevalo has no financial interest in any aspect of this report.