Pathology of cytomegalovirus retinitis treated with sustained release intravitreal ganciclovir

Antimicrobial guide to posterior segment infections

PURPOSE

This review article is meant to serve as a reference guide and to assist the treating physician in making an appropriate selection and duration of an antimicrobial agent.

METHODS

Literature review.

RESULTS

Infections of the posterior segment require prompt medical or surgical therapy to reduce the risk of permanent vision loss. While numerous options exist to treat these infections, doses and alternative therapies, especially with contraindications for first-line therapy, are often elusive. Antimicrobial agents to treat posterior segment infections can be administered via various routes, including topical, intravitreal, intravenous, and oral.

CONCLUSIONS

Although there are many excellent review articles on the management of endophthalmitis, we take the opportunity in this review to comprehensively summarize the appropriate antimicrobial regimen of both common and rare infectious etiologies of the posterior segment, using evidence from clinical trials and large case series.

The role of ganciclovir for the management of cytomegalovirus retinitis in HIV patients: Pharmacological review and update on new developments

OBJECTIVE

To review the pharmacology and pharmacokinetics of intravenous, oral and intraocular ganciclovir, and to discuss the role of these various formulations in the management of cytomegalovirus (CMV) retinitis in AIDS patients.

DATA SOURCES

A MEDLINE search (1987 through November 1995) of English-language literature using the main medical subject headings 'ganciclovir' and 'cytomegalovirus', and the subheading 'acquired immunodeficiency syndrome'. Relevant articles were also selected from references of identified articles. Abstracts from recent medical conferences of infectious diseases, pharmacology and human immunodeficiency virus were screened for additional data.

STUDY SELECTION AND DATA EXTRACTION

All articles and abstracts discussing the use of ganciclovir for the management or prophylaxis of CMV retinitis in AIDS patients were considered for inclusion. Pertinent information, as judged by the authors, was selected and synthesized for discussion.

DATA SYNTHESIS

Ganciclovir has demonstrated virustatic activity against CMV, and is often administered 5 mg/kg intravenously every 12 h as first-line therapy for CMV retinitis. Intravenous maintenance therapy at 5 mg/kg daily is usually effective at delaying retinitis progression for approximately 60 to 70 days. Neutropenia and thrombocytopenia are observed frequently, often necessitating interruption or discontinuation of therapy. Local drug administration may delay disease progression even further, and may be considered for patients who are intolerant to or failing intravenous therapy. However, systemic ganciclovir should be encouraged to reduce the risk of developing contralateral eye or end-organ CMV disease. Oral ganciclovir at 1 g tid is almost as effective as intravenous ganciclovir 5 mg/kg/day in delaying retinitis progression and is associated with fewer line-related complications. Absorption, drug interactions, cost and compliance should also be considered.

CONCLUSIONS

Until recently, ganciclovir was available only for intravenous use. Recent developments allow for intraocular and oral administration of this agent. A clear understanding of the advantages and disadvantages of these new formulations is required in order to select the most appropriate product for managing CMV retinitis in AIDS patients.

Fundus autofluorescence changes in cytomegalovirus retinitis

PURPOSE

The purpose of this study was to describe fundus autofluorescence imaging features of cytomegalovirus (CMV) retinitis and to correlate fundus autofluorescence features with clinical activity.

METHODS

A retrospective case series was undertaken to evaluate nine eyes of six patients with active CMV retinitis. Patients were evaluated with a comprehensive ophthalmic examination, fundus autofluorescence imaging, and fundus photography. Oral valganciclovir, intravitreal ganciclovir, intravitreal foscarnet, or an ganciclovir implant was administered as clinically indicated.

RESULTS

In all nine eyes with active CMV retinitis, a hyperautofluorescent signal on fundus autofluorescence imaging was correlated spatially with the border of advancing CMV retinitis. Stippled areas of alternating hyperautofluorescence and hypoautofluorescence were observed in regions of retinal pigment epithelium atrophy from prior CMV retinitis. In three eyes with subtle CMV reactivation, a hyperautofluorescent border was helpful in the detection and localization of active CMV retinitis. In another patient, diffuse, punctate hyperautofluorescence after intravitreal ganciclovir and foscarnet was a concern for medication-related toxicity.

CONCLUSION

Fundus autofluorescence imaging was valuable in highlighting areas of active CMV retinitis in all patients in this series, including two patients with subtle clinical features. Fundus autofluorescence may be useful as an adjunctive imaging modality for the detection of CMV activity and aid in our understanding of the structural changes during episodes of CMV retinitis.

Ultrasound biomicroscopic study of sclerotomy sites after implantation of sustained release drug devices

BACKGROUND/AIMS

To evaluate the potential of ultrasound biomicroscopy (UBM) as a tool to study the precise location and changes of sclerotomy sites of the eye with an intraocular drug delivery device.

METHODS

Eight eyes of six patients (13 sites) who received ganciclovir implants were examined by UBM. Examinations were performed 1-26 months (mean 12.8 months) postoperatively. Serial transverse and radial sections of the anterior ciliary body around the sclerotomy sites were obtained.

RESULTS

The ganciclovir implant contour was successfully viewed using an UBM with high reflectivity. Three implants were deviated anteriorly and they were very close to the ciliary body and the lens (anterior deviation), while four implants were deviated posteriorly and away from the lens (posterior deviation). The other six implants were located at the appropriate position as intended. A solitary homogeneous mass with a medium reflectivity around the suture tab was observed at 12 out of 13 sites in seven eyes. Thick membranes extending from sclerotomy sites to the ora serrata were found at two sites in two eyes.

CONCLUSION

UBM is helpful in detecting abnormal manifestations around ganciclovir implants and is a valuable tool to assess the changes of the sclerotomy sites of the sustained released intraocular devices.

Foreign body reaction with delayed extrusion of ganciclovir implant in a patient with immune recovery vitritis syndrome

PURPOSE

To report a case of delayed extrusion of primary ganciclovir implants in a patient with immune recovery vitritis syndrome.

METHOD

Interventional case report. A 54-year-old HIV positive male patient with immune recovery vitritis syndrome had spontaneous extrusion of bilateral ganciclovir devices 4 years after primary implantation.

RESULT

The extruded ganciclovir implants were removed from both eyes, and removal was complicated by vitreous hemorrhage in one eye. Histopathological examination of the extruded implant, LE, showed marked inflammation and evidence of foreign body reaction.

CONCLUSION

Excess inflammation in eyes with immune recovery vitritis syndrome may trigger a foreign body reaction that results in a delayed extrusion of primary ganciclovir implants. The site of ganciclovir implants in patients with immune recovery vitritis syndrome should be regularly inspected for eroding struts to prevent secondary endophthalmitis.

Treatment of cytomegalovirus retinitis with an intraocular sustained-release ganciclovir implant

The objective of this prospective study was to evaluate the efficacy and complications of the use of an intraocular sustained-release ganciclovir implant for the treatment of active cytomegalovirus (CMV) retinitis in AIDS patients. Thirty-nine eyes of 26 patients were submitted to ocular surgery. All patients underwent complete ocular examination before and after surgery. The surgical procedure was always done under local anesthesia using the same technique. The mean time for the surgical procedure was 20 min (range, 15 to 30 min). The average follow-up period was 3.7 months. Of all patient, only 4 presented recurrence of retinitis after 8, 8, 9 and 2 months, respectively. Three of them received a successful second implant. All 39 eyes of the 26 patients presented healing of retinitis as shown by clinical improvement evaluated by indirect binocular ophthalmoscopy and retinography. Retinitis healed within a period of 4 to 6 weeks in all patients, with clinical regression signs from the third week on. Six (15.4%) eyes developed retinal detachment. None of the patients developed CMV retinitis in the contralateral eye. The intraocular implant proved to be effective in controlling the progression of retinitis for a period of up to 8 months even in patients for whom systemic therapy with either ganciclovir or foscarnet or both had failed. The intraocular sustained-release ganciclovir implant proved to be a safe new procedure for the treatment of CMV retinitis, avoiding the systemic side effects caused by the intravenous medications and improving the quality of life of the patients.

Treatment of recurrent cytomegalovirus retinitis with the ganciclovir implant

PURPOSE

To evaluate preoperative characteristics and outcome of the treatment of recurrent cytomegalovirus (CMV) retinitis with the ganciclovir implant.

METHODS

Records of 54 patients with acquired immunodeficiency syndrome and active, previously treated CMV retinitis who received a ganciclovir implant in one (n = 31) or both (n = 23) eyes were reviewed. Entry criteria included prior insertion and removal of an indwelling catheter or failure to respond to tolerated doses of ganciclovir and foscarnet. Preoperative factors that might correlate with outcome were analyzed, including demographic factors, duration of human immunodeficiency virus disease and CMV retinitis, indications for surgery, prior anti-CMV treatment, and extent of retinitis.

RESULTS

Forty-six patients completed 1 month of follow-up and were analyzed for outcome. Thirty-one (67.4%) had inactive retinitis at 1 month vs 15 (32.6%) with active retinitis, and they received a mean of 23.5 +/- 22.9 weeks of preoperative ganciclovir vs 58.0 +/- 52.0 weeks in patients with active retinitis (P = .003). Involvement of more than 25% of retinal area by CMV retinitis was also correlated with activity at 1 month (P < .001). Patients who received implants because of lack of venous access had a median time to progression of 8.0 +/- 3.0 months vs 2.0 +/- 1.2 months for patients who had inadequate response or intolerance to intravenous medication (P = .073). Patients with 6 months or less vs more than 6 months of preoperative ganciclovir treatment had progression at a median time of 8.0 +/- 1.7 months vs 2.0 +/- 0.3 months, respectively (P = .016).

CONCLUSION

Longer duration of preoperative ganciclovir or larger area of CMV retinitis correlates with lower success of ganciclovir implant therapy for recurrent retinitis.

Virus infections of the eye

In reviewing the clinical features, diagnostic evaluations and therapies of the most common ocular viral infections we attempt to whet your appetite for attacking the numerous challenges in diagnosis and treatment of viral eye disease. The herpes viruses, HSV, VZV and CMV are the cause of significant ocular morbidity. HSV most commonly affects the cornea producing keratitis that can be recurrent and may lead to corneal clouding and neovascularisation. Manifestations can be purely infectious or immunological and treatment options must be tailored to the underlying pathophysiology. Herpes zoster ophthalmicus, caused by VZV infection of the first branch of the trigeminal nerve, produces a characteristic rash and can progress to keratitis and uveitis. HSV and VZV can cause retinitis in both immunocompetent and immunocompromised individuals. There has been a significant increase in the incidence of CMV retinitis since the beginning of the AIDS epidemic. We review the numerous new treatments, diagnostic tests and treatment strategies which have been developed in response to this potentially blinding retinal infection. Adenovirus produces an epidemic conjunctivitis and epidemic keratoconjunctivitis which are severe and extremely contagious conjunctival infections. HIV, molluscum contagiosum, EBV and rubeola also cause ocular diseases which are described.Copyright 1998 John Wiley & Sons, Ltd.

Biodegradable scleral implant for intravitreal controlled release of fluconazole

PURPOSE

To evaluate the feasibility of using a biodegradable polymeric scleral implant containing fluconazole (FLCZ), a bis-triazole antifungal agent, as a potential intravitreal-controlled drug delivery system.

METHODS

The scleral implants, loaded with 10, 20, 30, and 50% FLCZ, were prepared with biodegradable polymers of poly (DL-lactide-co-glycolide). Those with all loading doses were used for the in vitro release studies; those with 30% FLCZ were used for the intravitreal release studies in pigmented rabbits. The in vitro and in vivo release rates of FLCZ from the implants were measured periodically with spectrophotometry and high performance liquid chromatography, respectively. The effects of the implants on ocular tissues were evaluated ophthalmoscopically, histologically, and electrophysiologically.

RESULTS

The scleral implants loaded with 10, 20, and 30% doses gradually released FLCZ over 4 weeks in vitro; those with 50% FLCZ released most of the drug in one week. FLCZ concentration in the rabbit vitreous remained within the 99% inhibitory concentration for Candida albicans for 3 weeks after implantation. The scleral implant gradually biodegraded, and it disappeared by 4 months after implantation. The electrophysiologic and histopathologic findings demonstrated no substantial toxic reactions in the ocular tissues.

CONCLUSION

The current study suggests that a biodegradable, polymeric scleral implant containing FLCZ may be a promising intravitreal drug delivery system to treat fungal endophthalmitis.

Drug treatment of HIV-related opportunistic infections

The AIDS epidemic has led to the emergence of several disease entities which in the pre-AIDS era were rare or seemingly innocuous. Experience of treating these diseases varies. In some instances, such as Pneumocystis carinii pneumonia, there is an abundance of published literature to direct our course of action. However, for many of these newly recognised diseases our treatment experience is limited. Furthermore, in many instances, well controlled trials evaluating treatment modalities in the AIDS population are lacking. We have identified 13 disease entities (P. carinii pneumonia, toxoplasmosis, cryptococcosis, histoplasmosis, Mycobacterium tuberculosis, Mycobacterium avium complex, cytomegalovirus, coccidioidomycosis, isosporiasis, candidosis, Kaposi's sarcoma, herpes simplex virus, and varicella zoster virus) and have reviewed the current literature with regard to their treatment.

Release kinetics of liposome-encapsulated ganciclovir after intravitreal injection in rabbits

This study was undertaken to establish experimentally whether the intravitreal application of liposomally-entrapped ganciclovir could prolong intraocular therapeutic levels when it is compared to the intravitreal injection of a simple solution of the drug. New Zealand white rabbits were given an intravitreal injection of the drug solution and of liposome-encapsulated ganciclovir. The intravitreal clearance of ganciclovir was determined after a single injection of either the drug solution (200 micrograms/0.1 mL) or the liposomally-entrapped (with 41% load; 82 micrograms drug load and 118 micrograms free) ganciclovir. The ganciclovir vitreal concentrations were measured at various time intervals for a period up to 43 days using an HPLC method. The results of this study clearly demonstrated that prolonged intravitreal drug levels (above the mean inhibitory dose of cytomegalovirus of 1 microgram/mL) after administration of the liposome-entrapped ganciclovir and estimated to continue beyond 30-43 days. The injection of the 200 micrograms/0.1 mL of drug solution showed a mean vitreous concentration which was higher than the ID50 only for 55 h. The disappearance rate constant for the liposome-encapsulated injections was approximately 22 x slower than simple drug solution injections (controls). No evidence of retinal toxicity was found by clinical or light microscopy examination of the treated eyes.

Intravitreal ganciclovir for cytomegalovirus retinitis in patients with AIDS

OBJECTIVE

To assess the evolution of cytomegalovirus (CMV) retinitis and evaluate the possible complications associated with the use of intravitreal injections to treat this disease.

DESIGN

A nonrandomized, retrospective study with case series was performed. The study took place over 34 months.

SETTING

The study included patients with AIDS who developed CMV retinitis, and who were treated in the hospital, as outpatients, or both.

PATIENTS

Twelve patients with AIDS and CMV retinitis diagnosed between June 1990 through April 1993 were included in the study. MAIN PATIENT PARAMETERS AND OUTCOME MEASURES: For each patient, the following data were recorded: age, risk factors, other systemic findings, dates of AIDS and CMV retinitis diagnoses, stage of AIDS, extent of the retinitis, CD4 lymphocyte count at the time of diagnosis of retinitis, visual acuity, clinical evolution of the ocular infection, therapy, complications caused by the treatment, development on nonocular CMV, and the use of zidovudine or didanosine during the study period.

RESULTS

Vision improved or remained stable in nine patients and worsened in three. Two patients developed optic neuritis. The retinitis progressed to the other eye in only one of the eight patients who had unilateral involvement. The rate of relapse with maintenance therapy was 8.3% (n = 1) within the first 8 weeks. Treatment was well tolerated. There was no evidence of toxicity after a total of 226 intravitreal ganciclovir injections. All patients were able to tolerate zidovudine or didanosine concomitantly with intravitreal ganciclovir.

CONCLUSIONS

Intravitreal ganciclovir appears to be an effective alternate to systemic ganciclovir in patients with severe neutropenia and in patients who choose to continue receiving systemic zidovudine or didanosine. Early treatment and long-term maintenance therapy is essential for preserving sight.

Ganciclovir intraocular implant. A clinicopathologic study

BACKGROUND

Surgical implantation of the intraocular sustained-release ganciclovir device is a safe and effective treatment for cytomegalovirus (CMV) retinitis. Previous histopathologic studies on eyes containing such implants have been limited by the necessity of removing the device before processing. Microtome sectioning of hard plastics within paraffin-embedded blocks is infeasible, and the anatomic relations of implant to eye are destroyed.

METHODS

The authors studied four eyes from three patients who had undergone implant insertion. Globes with implants in place were fixed in neutral 10% formation, embedded in methylmethacrylate, sectioned on a special microtome, and stained with hematoxylin-eosin.

RESULTS

After methacrylate embedding, the precise anatomic relations of the implant to the neighboring uveoscleral coats were preserved. In two eyes, the suture tab of the implant protruded through the sclera, exiting subconjunctivally. In two eyes, the implant was totally intravitreal. In all patients, the device was supported by fibrous tissue which emanated from a surgical coloboma of the pars plana ciliaris. Focal granulomatous inflammation adjoined suture and implant materials but no other inflammation or deleterious effects on the ocular structures were noted.

CONCLUSION

This report is the first to document the intraocular histopathology of the ganciclovir implant. The subconjunctival location, enhancing the potential for endophthalmitis, may be avoided by trimming of the suture tab close to the anchoring suture and not tying it too tightly. Methylmethacrylate embedding is a useful technique for preserving the microanatomy of intraocular implants.

Local therapy for cytomegalovirus retinopathy

PURPOSE

We sought to understand better the efficacy and risks of local therapies (direct placement of drug into the eye) for the treatment of cytomegalovirus retinopathy. This understanding can be used to design rational treatment regimens, to formulate indications for use of local therapy, and to establish criteria for assessment of future results in this area.

METHODS

We collected information about local therapies through a review of published literature.

RESULTS

Intraocular injection of ganciclovir and foscarnet and implantation of intraocular devices that slowly release ganciclovir are able to decrease the activity of cytomegalovirus retinopathy lesions and prevent their enlargement for variable periods of time. The time to disease progression (lesion enlargement) may be longer with intraocular devices than with current treatments using intravenously administered antiviral drugs. Local therapies have many advantages (for example, convenience, reduced cost, and lack of systemic toxicity), but there are potential disadvantages, including endophthalmitis, increased rates of retinal detachment, and development of nonocular cytomegalovirus disease and cytomegalovirus retinopathy in fellow, uninvolved eyes.

CONCLUSIONS

Local therapies are effective for the treatment of cytomegalovirus retinopathy, but their relative risks and benefits, when compared with those of intravenous drug therapy, have yet to be fully evaluated. We anticipate that local therapy will be an important treatment modality for selected patients with cytomegalovirus retinopathy. Indications include the use of local therapy as an alternative therapy for patients who are unable to receive systemic therapy (intolerance to intravenous or oral medication, or lack of intravenous access) and as supplementation in patients whose retinal disease is incompletely controlled by maximum tolerated systemic medications. The use of local therapy as sole initial treatment in lieu of systemic therapy remains controversial. Its most useful role may be in conjunction with oral forms of antiviral drugs now in development.

Passage of drugs through different intraocular microdialysis membranes

BACKGROUND

Since drug penetration from the blood to the vitreous body is very poor, it is important to find means other than systemic delivery to reach necessary intraocular concentrations of drugs. This study represents a step in this direction.

METHOD

Microdialysis probes implanted intraocularly in rabbits were perfused with different substances, mainly drugs. The substances belonged to three groups, antibiotics, corticosteroids and cytostatics, and were: benzylpenicillin and cefuroxim; triamcinolone and dexamethasone; daunomycin and 5-fluorouracil. In addition, three substances of different molecular weights were tested: formic acid (MW 70), glucose (MW 189) and insulin (MW ca. 5200).

RESULTS

When used in tracer concentrations, some lipophilic drugs stick to polycarbonate but not to polyamide membranes. The latter material has therefore been used in all intraocular perfusions. All substances except inulin were found to diffuse through the polyamide membrane into the vitreous at a rate of about 10-20% of the perfusate concentration. Membranes with different dimensions and the above-mentioned two materials have also been screened for their transport properties in vitro. No differences were found between the two membrane materials, polycarbonate and polyamide. The net dialysis is strongly dependent on the probe geometry.

CONCLUSIONS

We have shown that the above-mentioned substances penetrate into the vitreous body of rabbits through an implanted microdialysis membrane. This is of importance for the development of new means of intraocular drug administration.

Current management of cytomegalovirus disease in patients with AIDS

Cytomegalovirus (CMV) infection is common in both homosexual and heterosexual HIV-infected patients, and causes disease in a substantial proportion of patients with AIDS and very low CD4+ cell counts. Both ganciclovir, an analog of the nucleoside guanosine, and foscarnet, an analog of pyrophosphate, are licensed for treatment of CMV retinitis. They may also have a role in the treatment of gastrointestinal disease caused by CMV. In the Studies of Ocular Complications of AIDS comparative trial the two agents were equally effective against CMV retinitis, but patients receiving foscarnet had significantly longer survival, even after adjusting for covariates including antiretroviral therapy. Ongoing studies are evaluating higher dosages of foscarnet for maintenance therapy and combined therapy with ganciclovir and foscarnet. Tolerance of ganciclovir therapy has been facilitated by adjunctive therapy with colony-stimulating factors. Because both ganciclovir and foscarnet must be administered by intravenous infusion and are associated with significant toxicities, other anti-CMV agents are under active development, including HPMPC and an oral formulation of ganciclovir. Management of CMV retinitis involves individualizing therapy, balancing side effects and administration requirements, and, in many clinical settings, the overall cost of treatment.