ACUTE RETINAL NECROSIS SECONDARY TO MULTIDRUGRESISTANT HERPES SIMPLEX VIRUS 2 IN AN IMMUNOCOMPETENT ADOLESCENT Adrian T. Dokey, MD,* Sara J. Haug, MD, PhD,*† H. Richard McDonald, MD,*† Emmett T. Cunningham, Jr., MD, PhD,*†‡ Brandon J. Lujan, MD,*†§ Arthur D. Fu, MD,*† J. Michael Jumper, MD*†
Purpose: To report the clinical course of a patient with acute retinal necrosis resulting from a multidrug-resistant strain of herpes simplex virus 2. Methods: Observational case report. Results: A 17-year-old man with no identifiable immune deficiency presented with pain and decreased vision in his left eye. He had dense anterior and posterior segment inflammation with retinal whitening suggestive of acute retinal necrosis, which progressed despite treatment with intravenous acyclovir, methylprednisolone, and ganciclovir. A transition to intravitreal and intravenous foscarnet led to clinical improvement. Genetic analysis revealed the etiology to be a multidrug-resistant strain of herpes simplex virus 2. Conclusion: Antiviral resistance is an uncommon finding among viruses causing acute retinal necrosis in immunocompetent patients. Patients with these infections may be adequately treated with prompt recognition and a change in therapy to alternative antiviral agents such as foscarnet. RETINAL CASES & BRIEF REPORTS 8:260–264, 2014
Intravenous acyclovir has been the standard first-line treatment of ARN, and although varicella zoster virus resistance to acyclovir is uncommon, rates of resistance among HSV strains in uveitis patients range from 0.1% to 0.7% in immunocompetent patients to 3.5% to 10% in immunocompromised patients.2,3 For these patients, other nucleoside analogs such as ganciclovir and famciclovir are often cross-resistant and alternative antiviral therapies such as foscarnet or cidofovir may be required for adequate control.3 In this report, we describe a case of ARN resulting from a strain of HSV-2 resistant to acyclovir and ganciclovir, but sensitive to foscarnet, in an otherwise healthy young man.
From the *Department of Ophthalmology, California Pacific Medical Center, San Francisco, California; †West Coast Retina Medical Group, San Francisco, California; ‡Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, California; and §Department of Vision Science, Berkeley School of Optometry, University of California, Berkeley, California.
A
cute retinal necrosis (ARN) was first described by Urayama et al1 in 1971 as an acute unilateral panuveitis with periarteritis that progressed to diffuse necrotizing retinitis and, ultimately, rhegmatogenous retinal detachment. It is now known to be associated with the herpes family of viruses, most commonly varicella zoster virus and herpes simplex virus (HSV). Antiviral agents are the mainstay of therapy for this source of devastating intraocular inflammation.2
Case Report A 17-year-old man presented with severe pain and decreased vision in his left eye that had been worsening over the last 5 days. The patient’s medical history was significant for a history of asthma
260
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261
Fig. 1. A. External photograph showing complete blepharoptosis of the left eye. B. When the lid is mechanically opened, the conjunctiva appears injected with a mid-dilated pupil.
but was otherwise unremarkable with no history of sexually transmitted diseases. Visual acuity was 20/20 in the right eye and light perception in the left. Intraocular pressures were 15 and 19, respectively. Anterior segment examination of the right was normal. On the left, there was complete blepharoptosis with 2+ conjunctival injection (Figure 1). The cornea had microcystic edema and the anterior chamber showed 2+ cell. Posterior segment examination on the right revealed small areas of chorioretinal scar in the macula with no vitritis or retinitis. Fundus examination on the left showed a hazy view with 3+ vitritis, a swollen optic nerve, and areas of peripheral retinal whitening (Figure 2). The patient was admitted for intravenous acyclovir, 800 mg every 8 hours. Laboratory test results, including Rapid Plasma Reagin (RPR) and FTA-Abs, toxoplasmosis, and HIV, were negative. High-dose intravenous methylprednisolone treatment was then initiated at a dose of 500 mg every 12 hours. Immediately after steroid treatment, the patient’s pain, vision, and ptosis improved. After 2 days of intravenous acyclovir and methylprednisolone, vision in the left eye was 20/100. However, the peripheral retinitis continued to move posteriorly. Intravenous ganciclovir (400 mg every 12 hours) was added to the treatment regimen. On the third day of treatment, visual acuity on the left dropped to counting fingers and the vitritis and retinitis had worsened. The patient was taken for diagnostic vitrectomy. At the time of surgery, 360° endolaser barricade was also performed. After the biopsy, the patient received intravitreal vancomycin (1 mg/0.1 mL), ceftazidime (2 mg/0.1 mL), amphotericin (5 mcg/0.1mL), and foscarnet (1,200 mg/0.1 mL). Polymerase chain reaction results were positive for HSV-2 and negative for HSV-1, cytomegalovirus, and varicella zoster virus. Given the clinical resistance to acyclovir and ganciclovir of the HSV-2 virus, the patient was transitioned to intravenous foscarnet (3,200 mg every 8 hours). Four days after transitioning to foscarnet, the peripheral retinitis was no longer progressing and the vitritis had improved (Figure 3). On careful examination of the fundus, superficial retinal precipitates were realized most notably along the retinal vessels, both veins and arterioles (Figure 4), but also concentrated at the optic disk and the fovea (Figure 5). En face images of the optic disk and fovea show the opacities creating a ring that resulted in corrugation of the inner retinal layers (Figure 6). Three weeks after initiating foscarnet therapy, the retinitis was no longer active and the optic disk swelling had resolved Presented at the Pacific Retina Club Meeting, Los Angeles, CA, April 2013. None of the authors have any financial/conflicting interests to disclose. Reprint requests: J. Michael Jumper, MD, West Coast Retina Medical Group, 1445 Bush Street, San Francisco, CA 94941; e-mail: wcr@westcoastretinacom
Fig. 2. Color fundus photograph of the right (A) and left (B) eyes. A. The right eye has small areas of chorioretinal scar inferior to the fovea. B. The left eye has a hazy view because of vitritis with a swollen optic nerve.
(Figure 7). Genotype analysis indicated a multidrug-resistant virus. Given the aggressive nature of the infection, the patient is currently maintained on valacyclovir, 500 mg 4 times daily. Two months after presentation, the patient developed retinal detachment and proliferative vitreoretinopathy. He underwent repair, including scleral buckle, vitrectomy, membrane peeling, air–fluid exchange, endolaser, and placement of C3F8 gas tamponade. One month later, he redetached and underwent vitrectomy, lensectomy, membrane peeling, air–fluid exchange, endolaser, and placement of silicone oil. The retina was attached at most recent follow-up four months after initial presentation and one month after the last surgery.
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Fig. 5. Spectral domain optical coherence tomography image of the left macula showing the bubble-like opacities seen in Figure 4 along the surface of the retina at the fovea. These opacities are also leading to shadowing of the retina.
Fig. 3. Color fundus montage photograph of the left eye, taken 4 days after transitioning to foscarnet. The peripheral retinitis is no longer advancing posteriorly, the vitritis is improved and the optic disk swelling has diminished.
Discussion This patient had panuveitis and ARN with partial third nerve palsy secondary to multidrug-resistant HSV-2, which was responsive to foscarnet. After its description by Urayama in 1971, ARN syndrome was later defined in 1994 by the Executive Committee of the American Uveitis Society as: 1) 1 or more foci of retinal necrosis with discrete borders located in the peripheral retina; 2) rapid progression in the absence of antiviral therapy; 3) circumferential spread; 4) evidence of occlusive vasculopathy with arterial involvement; and 5) a prominent inflammatory reaction in the vitreous and anterior chambers.4 Other
Fig. 4. Color fundus photograph of the left eye showing bubble-like opacities (shown by arrows) along the retinal vessels.
clinical features include fellow-eye involvement in up to one third of patients and rhegmatogenous retinal detachment in half to three quarters of eyes.2 Witmer et al5 reported a case of segmental periarteriolar plaques (Kyrieleis plaques) in a patient with HSV-2 associated ARN. The appearance of the plaques in this case is similar to Kyrieleis plaques and likely represents an inflammatory response. However, the superficial retinal precipitates seen in this case are unique in that they are not limited to the arterial surface. They are also distinct from superficial retinal precipitates such as those seen in syphilitic retinitis6 given that they are clearer in color and many of the precipitates are aligned with the retinal vessels. Acyclovir is the antiviral drug of choice in patients with herpetic uveitis, and it requires phosphorylation by both viral thymidine kinase and cellular enzymes before it can inhibit viral DNA polymerase.7,8 Though mutations in the viral DNA polymerase gene may confer resistance, the majority of acyclovir-resistant isolates demonstrate a mutation in the viral thymidine kinase gene.3,8 Other nucleoside analogs such as ganciclovir are also dependent on viral thymidine kinase, and a case series by van Velzen et al7 showed 3 of 4 acyclovir-resistant viruses isolated from intraocular fluid to be cross-resistant to ganciclovir. These patients can be treated with drugs that inhibit viral DNA polymerase independent of the action of viral thymidine kinase and show low rates of crossresistance, such as foscarnet and cidofovir.2,3,7 Wong et al2 also advocate the use of adjunctive intravitreal foscarnet or ganciclovir for patients in whom the retinitis threatens the optic nerve or macula. Evidence of antiviral resistance in this case was demonstrated by both clinical progression while on acyclovir and a persistent positive result on polymerase chain reaction analysis.9 Because resistant HSV strains have mutations in the machinery necessary for viral replication, their relative pathogenicity is often decreased.3 These viruses are more likely to replicate successfully in the setting of an
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Fig. 7. Color montage fundus photograph of the left eye 3 weeks after transitioning to foscarnet. There seems to be no active peripheral retinitis, and the vitritis has improved. There are sclerotic vessels of the superior and inferior aspect of the optic disk. The optic disk edema has resolved.
that showed 33% of patients obtaining a final visual acuity of 20/60 or better. In summary, this patient developed ARN secondary to a multidrug-resistant strain of HSV-2. His clinical disease was controlled with foscarnet, and he has since been maintained without recurrence on valacyclovir. His course has been complicated by proliferative vitreoretinopathy and retinal detachments requiring two surgeries, and he will continue to require close monitoring throughout his recovery. Key words: HSV, HSV retinitis, acute retinal necrosis, acyclovir resistance, multidrug resistance. References
Fig. 6. En face optical coherence tomography images of the left fovea (A) and the left optic disk (B). In both images, the bubble-like opacities form a ring that results in corrugation of the inner retinal surface.
impaired host immune response, and the prevalence of resistant viruses in immunosuppressed patients with HSV uveitis is 3.5% to 10% compared with 0.1% to 0.7% among immunocompetent patients.3 No correlation has yet been demonstrated between acyclovir resistance and disease outcome, which may be due, in part, to the reduced viral fitness of drug-resistant mutants.3,7 However, the prognosis remains guarded for many patients, with a case series by Tran et al10
1. Urayama A, Yamada N, Sasaki T. Unilateral acute uveitis with periarteritis and detachment. Jpn J Clin Ophthalmol 1971;25:607–619. 2. Wong RW, Jumper JM, McDonald HR, et al. Emerging concepts in the management of acute retinal necrosis. Br J Ophthalmol 2013;97:545–552. 3. Piret J, Boivin G. Resistance of herpes simplex viruses to nucleoside analogues: mechanisms, prevalence, and management. Antimicrob Agents Chemother 2011;55:459–472. 4. Holland GN. Standard diagnostic criteria for the acute retinal necrosis syndrome. Executive Committee of the American Uveitis Society. Am J Ophthalmol 1994;117:663–667. 5. Witmer MT, Levy-Clarke GA, Fouraker BD, Madow B. Kyrieleis plaques associated with acute retinal necrosis from herpes simplex virus type 2. Retin Cases Brief Rep 2011;5:297–301. 6. Fu EX, Geraets RL, Dodds EM, et al. Superficial retinal precipitates in patients with syphilitic retinitis. Retina 2010;30:1135–1143.
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7. van Velzen M, Missotten T, van Loenen FB, et al. Acyclovirresistant herpes simplex virus type 1 in intra-ocular fluid samples of herpetic uveitis patients. J Clin Virol 2013;57:215–221. 8. Sauerbrei A, Bohn K, Heim A, et al. Novel resistanceassociated mutations of thymidine kinase and DNA polymerase genes of herpes simplex virus type 1 and type 2. Antivir Ther 2011;16:1297–1308.
9. Inoue T, Kawashima R, Suzuki T, Ohashi Y. Real-time PCR for diagnosing acyclovir-resistant herpetic keratitis based on changes in viral DNA copy number before and after treatment. Arch Ophthalmol 2012;130:1462–1464. 10. Tran TH, Stanescu D, Caspers-Velu L, et al. Clinical characteristics of acute HSV-2 retinal necrosis. Am J Ophthalmol 2004;137:872–879.
Purpose: To report the clinical course of a patient with acute retinal necrosis resulting from a multidrug-resistant strain of herpes simplex virus 2. Methods: Observational case report. Results: A 17-year-old man with no identifiable immune deficiency presented with pain and decreased vision in his left eye. He had dense anterior and posterior segment inflammation with retinal whitening suggestive of acute retinal necrosis, which progressed despite treatment with intravenous acyclovir, methylprednisolone, and ganciclovir. A transition to intravitreal and intravenous foscarnet led to clinical improvement. Genetic analysis revealed the etiology to be a multidrug-resistant strain of herpes simplex virus 2. Conclusion: Antiviral resistance is an uncommon finding among viruses causing acute retinal necrosis in immunocompetent patients. Patients with these infections may be adequately treated with prompt recognition and a change in therapy to alternative antiviral agents such as foscarnet. RETINAL CASES & BRIEF REPORTS 8:260–264, 2014
Intravenous acyclovir has been the standard first-line treatment of ARN, and although varicella zoster virus resistance to acyclovir is uncommon, rates of resistance among HSV strains in uveitis patients range from 0.1% to 0.7% in immunocompetent patients to 3.5% to 10% in immunocompromised patients.2,3 For these patients, other nucleoside analogs such as ganciclovir and famciclovir are often cross-resistant and alternative antiviral therapies such as foscarnet or cidofovir may be required for adequate control.3 In this report, we describe a case of ARN resulting from a strain of HSV-2 resistant to acyclovir and ganciclovir, but sensitive to foscarnet, in an otherwise healthy young man.
From the *Department of Ophthalmology, California Pacific Medical Center, San Francisco, California; †West Coast Retina Medical Group, San Francisco, California; ‡Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, California; and §Department of Vision Science, Berkeley School of Optometry, University of California, Berkeley, California.
A
cute retinal necrosis (ARN) was first described by Urayama et al1 in 1971 as an acute unilateral panuveitis with periarteritis that progressed to diffuse necrotizing retinitis and, ultimately, rhegmatogenous retinal detachment. It is now known to be associated with the herpes family of viruses, most commonly varicella zoster virus and herpes simplex virus (HSV). Antiviral agents are the mainstay of therapy for this source of devastating intraocular inflammation.2
Case Report A 17-year-old man presented with severe pain and decreased vision in his left eye that had been worsening over the last 5 days. The patient’s medical history was significant for a history of asthma
260
ARN SECONDARY TO MULTIDRUG-RESISTANT HSV-2
261
Fig. 1. A. External photograph showing complete blepharoptosis of the left eye. B. When the lid is mechanically opened, the conjunctiva appears injected with a mid-dilated pupil.
but was otherwise unremarkable with no history of sexually transmitted diseases. Visual acuity was 20/20 in the right eye and light perception in the left. Intraocular pressures were 15 and 19, respectively. Anterior segment examination of the right was normal. On the left, there was complete blepharoptosis with 2+ conjunctival injection (Figure 1). The cornea had microcystic edema and the anterior chamber showed 2+ cell. Posterior segment examination on the right revealed small areas of chorioretinal scar in the macula with no vitritis or retinitis. Fundus examination on the left showed a hazy view with 3+ vitritis, a swollen optic nerve, and areas of peripheral retinal whitening (Figure 2). The patient was admitted for intravenous acyclovir, 800 mg every 8 hours. Laboratory test results, including Rapid Plasma Reagin (RPR) and FTA-Abs, toxoplasmosis, and HIV, were negative. High-dose intravenous methylprednisolone treatment was then initiated at a dose of 500 mg every 12 hours. Immediately after steroid treatment, the patient’s pain, vision, and ptosis improved. After 2 days of intravenous acyclovir and methylprednisolone, vision in the left eye was 20/100. However, the peripheral retinitis continued to move posteriorly. Intravenous ganciclovir (400 mg every 12 hours) was added to the treatment regimen. On the third day of treatment, visual acuity on the left dropped to counting fingers and the vitritis and retinitis had worsened. The patient was taken for diagnostic vitrectomy. At the time of surgery, 360° endolaser barricade was also performed. After the biopsy, the patient received intravitreal vancomycin (1 mg/0.1 mL), ceftazidime (2 mg/0.1 mL), amphotericin (5 mcg/0.1mL), and foscarnet (1,200 mg/0.1 mL). Polymerase chain reaction results were positive for HSV-2 and negative for HSV-1, cytomegalovirus, and varicella zoster virus. Given the clinical resistance to acyclovir and ganciclovir of the HSV-2 virus, the patient was transitioned to intravenous foscarnet (3,200 mg every 8 hours). Four days after transitioning to foscarnet, the peripheral retinitis was no longer progressing and the vitritis had improved (Figure 3). On careful examination of the fundus, superficial retinal precipitates were realized most notably along the retinal vessels, both veins and arterioles (Figure 4), but also concentrated at the optic disk and the fovea (Figure 5). En face images of the optic disk and fovea show the opacities creating a ring that resulted in corrugation of the inner retinal layers (Figure 6). Three weeks after initiating foscarnet therapy, the retinitis was no longer active and the optic disk swelling had resolved Presented at the Pacific Retina Club Meeting, Los Angeles, CA, April 2013. None of the authors have any financial/conflicting interests to disclose. Reprint requests: J. Michael Jumper, MD, West Coast Retina Medical Group, 1445 Bush Street, San Francisco, CA 94941; e-mail: wcr@westcoastretinacom
Fig. 2. Color fundus photograph of the right (A) and left (B) eyes. A. The right eye has small areas of chorioretinal scar inferior to the fovea. B. The left eye has a hazy view because of vitritis with a swollen optic nerve.
(Figure 7). Genotype analysis indicated a multidrug-resistant virus. Given the aggressive nature of the infection, the patient is currently maintained on valacyclovir, 500 mg 4 times daily. Two months after presentation, the patient developed retinal detachment and proliferative vitreoretinopathy. He underwent repair, including scleral buckle, vitrectomy, membrane peeling, air–fluid exchange, endolaser, and placement of C3F8 gas tamponade. One month later, he redetached and underwent vitrectomy, lensectomy, membrane peeling, air–fluid exchange, endolaser, and placement of silicone oil. The retina was attached at most recent follow-up four months after initial presentation and one month after the last surgery.
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Fig. 5. Spectral domain optical coherence tomography image of the left macula showing the bubble-like opacities seen in Figure 4 along the surface of the retina at the fovea. These opacities are also leading to shadowing of the retina.
Fig. 3. Color fundus montage photograph of the left eye, taken 4 days after transitioning to foscarnet. The peripheral retinitis is no longer advancing posteriorly, the vitritis is improved and the optic disk swelling has diminished.
Discussion This patient had panuveitis and ARN with partial third nerve palsy secondary to multidrug-resistant HSV-2, which was responsive to foscarnet. After its description by Urayama in 1971, ARN syndrome was later defined in 1994 by the Executive Committee of the American Uveitis Society as: 1) 1 or more foci of retinal necrosis with discrete borders located in the peripheral retina; 2) rapid progression in the absence of antiviral therapy; 3) circumferential spread; 4) evidence of occlusive vasculopathy with arterial involvement; and 5) a prominent inflammatory reaction in the vitreous and anterior chambers.4 Other
Fig. 4. Color fundus photograph of the left eye showing bubble-like opacities (shown by arrows) along the retinal vessels.
clinical features include fellow-eye involvement in up to one third of patients and rhegmatogenous retinal detachment in half to three quarters of eyes.2 Witmer et al5 reported a case of segmental periarteriolar plaques (Kyrieleis plaques) in a patient with HSV-2 associated ARN. The appearance of the plaques in this case is similar to Kyrieleis plaques and likely represents an inflammatory response. However, the superficial retinal precipitates seen in this case are unique in that they are not limited to the arterial surface. They are also distinct from superficial retinal precipitates such as those seen in syphilitic retinitis6 given that they are clearer in color and many of the precipitates are aligned with the retinal vessels. Acyclovir is the antiviral drug of choice in patients with herpetic uveitis, and it requires phosphorylation by both viral thymidine kinase and cellular enzymes before it can inhibit viral DNA polymerase.7,8 Though mutations in the viral DNA polymerase gene may confer resistance, the majority of acyclovir-resistant isolates demonstrate a mutation in the viral thymidine kinase gene.3,8 Other nucleoside analogs such as ganciclovir are also dependent on viral thymidine kinase, and a case series by van Velzen et al7 showed 3 of 4 acyclovir-resistant viruses isolated from intraocular fluid to be cross-resistant to ganciclovir. These patients can be treated with drugs that inhibit viral DNA polymerase independent of the action of viral thymidine kinase and show low rates of crossresistance, such as foscarnet and cidofovir.2,3,7 Wong et al2 also advocate the use of adjunctive intravitreal foscarnet or ganciclovir for patients in whom the retinitis threatens the optic nerve or macula. Evidence of antiviral resistance in this case was demonstrated by both clinical progression while on acyclovir and a persistent positive result on polymerase chain reaction analysis.9 Because resistant HSV strains have mutations in the machinery necessary for viral replication, their relative pathogenicity is often decreased.3 These viruses are more likely to replicate successfully in the setting of an
263
ARN SECONDARY TO MULTIDRUG-RESISTANT HSV-2
Fig. 7. Color montage fundus photograph of the left eye 3 weeks after transitioning to foscarnet. There seems to be no active peripheral retinitis, and the vitritis has improved. There are sclerotic vessels of the superior and inferior aspect of the optic disk. The optic disk edema has resolved.
that showed 33% of patients obtaining a final visual acuity of 20/60 or better. In summary, this patient developed ARN secondary to a multidrug-resistant strain of HSV-2. His clinical disease was controlled with foscarnet, and he has since been maintained without recurrence on valacyclovir. His course has been complicated by proliferative vitreoretinopathy and retinal detachments requiring two surgeries, and he will continue to require close monitoring throughout his recovery. Key words: HSV, HSV retinitis, acute retinal necrosis, acyclovir resistance, multidrug resistance. References
Fig. 6. En face optical coherence tomography images of the left fovea (A) and the left optic disk (B). In both images, the bubble-like opacities form a ring that results in corrugation of the inner retinal surface.
impaired host immune response, and the prevalence of resistant viruses in immunosuppressed patients with HSV uveitis is 3.5% to 10% compared with 0.1% to 0.7% among immunocompetent patients.3 No correlation has yet been demonstrated between acyclovir resistance and disease outcome, which may be due, in part, to the reduced viral fitness of drug-resistant mutants.3,7 However, the prognosis remains guarded for many patients, with a case series by Tran et al10
1. Urayama A, Yamada N, Sasaki T. Unilateral acute uveitis with periarteritis and detachment. Jpn J Clin Ophthalmol 1971;25:607–619. 2. Wong RW, Jumper JM, McDonald HR, et al. Emerging concepts in the management of acute retinal necrosis. Br J Ophthalmol 2013;97:545–552. 3. Piret J, Boivin G. Resistance of herpes simplex viruses to nucleoside analogues: mechanisms, prevalence, and management. Antimicrob Agents Chemother 2011;55:459–472. 4. Holland GN. Standard diagnostic criteria for the acute retinal necrosis syndrome. Executive Committee of the American Uveitis Society. Am J Ophthalmol 1994;117:663–667. 5. Witmer MT, Levy-Clarke GA, Fouraker BD, Madow B. Kyrieleis plaques associated with acute retinal necrosis from herpes simplex virus type 2. Retin Cases Brief Rep 2011;5:297–301. 6. Fu EX, Geraets RL, Dodds EM, et al. Superficial retinal precipitates in patients with syphilitic retinitis. Retina 2010;30:1135–1143.
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7. van Velzen M, Missotten T, van Loenen FB, et al. Acyclovirresistant herpes simplex virus type 1 in intra-ocular fluid samples of herpetic uveitis patients. J Clin Virol 2013;57:215–221. 8. Sauerbrei A, Bohn K, Heim A, et al. Novel resistanceassociated mutations of thymidine kinase and DNA polymerase genes of herpes simplex virus type 1 and type 2. Antivir Ther 2011;16:1297–1308.
9. Inoue T, Kawashima R, Suzuki T, Ohashi Y. Real-time PCR for diagnosing acyclovir-resistant herpetic keratitis based on changes in viral DNA copy number before and after treatment. Arch Ophthalmol 2012;130:1462–1464. 10. Tran TH, Stanescu D, Caspers-Velu L, et al. Clinical characteristics of acute HSV-2 retinal necrosis. Am J Ophthalmol 2004;137:872–879.
