Intraocular pressure and aqueous humor dynamics in patients with AIDS treated with intravitreal cidofovir (HPMPC) for cytomegalovirus retinitis

The Impact of Systemic Medications on Retinal Function

This study will provide a thorough review of systemic (and select intravitreal) medications, along with illicit drugs that are capable of causing various patterns of retinal toxicity. The diagnosis is established by taking a thorough medication and drug history, and then by pattern recognition of the clinical retinal changes and multimodal imaging features. Examples of all of these types of toxicity will be thoroughly reviewed, including agents that cause retinal pigment epithelial disruption (hydroxychloroquine, thioridazine, pentosan polysulfate sodium, dideoxyinosine), retinal vascular occlusion (quinine, oral contraceptives), cystoid macular edema/retinal edema (nicotinic acid, sulfa-containing medications, taxels, glitazones), crystalline deposition (tamoxifen, canthaxanthin, methoxyflurane), uveitis, miscellaneous, and subjective visual symptoms (digoxin, sildenafil). The impact of newer chemotherapeutics and immunotherapeutics (tyrosine kinase inhibitor, mitogen-activated protein kinase kinase, checkpoint, anaplastic lymphoma kinase, extracellular signal-regulated kinase inhibitors, and others), will also be thoroughly reviewed. The mechanism of action will be explored in detail when known. When applicable, preventive measures will be discussed, and treatment will be reviewed. Illicit drugs (cannabinoids, cocaine, heroin, methamphetamine, alkyl nitrite), will also be reviewed in terms of the potential impact on retinal function.

Pharmacologically induced uveitis

Treatments of numerous systemic and local diseases of different etiologies may be accompanied by an unwanted side effect in the form of uveitis. We inform readers about medications that have the potential to cause uveitis and analyze the strength of association of these medications with uveitis. Subsequently, cessation of medication or appropriate treatment can be individualized for each patient for the purpose of preventing further damage to tissue structure and function. Being aware of these associations, physicians may readily identify medications that may cause uveitis and avoid expensive and unnecessary clinical and laboratory testing.

Drug-induced Uveitis in HIV Patients with Ocular Opportunistic Infections

Purpose: To describe drug-induced uveitis in immunocompromised patients diagnosed with Human Immunodeficiency Virus (HIV) infection Methods: Narrative Review Results: Systemic and intraocular medications administered for the treatment of acquired immune deficiency syndrome (AIDS)-associated diseases in patients infected with HIV are a well-known cause of uveitis. Conclusions: Cidofovir and rifabutin, among other novel anti-retroviral therapies, are strongly associated with drug-induced uveitis. It is imperative to understand the pathogenesis, clinical findings, and management of HIV patients with uveitis induced by these agents.

Intraocular pressure in patients with human immunodeficiency virus, correlation with TCD4, viral load and demographic characteristics: a case-control study

Purpose

To compare if patients with HIV have lower intraocular pressure than patients without HIV.

Methods

The association of intraocular pressure corrected by pachymetry and the relationship with viral load (VL) and TCD4 cells was studied. A total of 99 patients with HIV (91 who were on regular treatment and in control of the disease - group 1; and 8 who were without treatment - group 2) and 100 controls were studied.

Results

Only age was of statistical significance; the group with HIV without control of the disease was the youngest. There was a decrease of -1.54 mmHg in the IOP of group 1 in relation to the controls and -3.63 mmHg in the IOP of group 2 in relation to the controls.

Conclusion

HIV patients had lower IOP than the control population. However, the relationship between IOP, VL and TCD4 was not found.

Association of Intraocular Pressure With Human Immunodeficiency Virus

PURPOSE

Prior studies have shown an association between human immunodeficiency virus (HIV) and reduced intraocular pressures (IOP). The purpose of this study was to determine if patients with HIV on highly active antiretroviral therapy (HAART) had any difference in their IOP compared with patients without HIV or with HIV who are not on HAART.

DESIGN

Retrospective cross-sectional study.

METHODS

We included 400 patients from our academic eye center between 2000 and 2016. Group 1 (G1) consisted of patients with HIV on HAART (n = 176), Group 2 (G2) consisted of patients with HIV who were not on HAART (n = 48), and Group 3 (G3) consisted of controls without HIV (n = 176). An analysis of variance (ANOVA) was performed to compare mean IOP values. Multivariate linear and logistic regression models were performed to assess factors impacting IOP. Difference in IOP was the primary outcome being measured.

RESULTS

The mean IOPs in mm Hg were 13.7 ± 5.1 (G1), 13.1 ± 3.6 (G2), and 17.3 ± 3.8 (G3), P < .01. In regression modeling, having a CD4 count ≤700 cells/mm³ contributed to a 2.1 mm Hg decrease in IOP. Patients with HIV were 7 times more likely to have an IOP ≤10 mm Hg, and patients with a CD4 count ≤700 cells/mm³ were 13 times more likely to have an IOP ≤10 mm Hg.

CONCLUSIONS

Absolute CD4 counts may play a role in IOP fluctuations. This association was found in patients with HIV regardless of whether patients were on HAART.

Drug-induced uveitis

INTRODUCTION

Drug-induced uveitis is a well described but often overlooked and/or misdiagnosed adverse reaction to medication. There are an increasing number of medications that have been related to the onset of intraocular inflammation. Identification of these inciting agents may decisively help the diagnostic algorithm involving new cases of uveitis.

AREAS COVERED

This review intends to be an updated comprehensive, practical guide for practitioners regarding the main drugs that have been associated with uveitis. A classification proposed by Naranjo et al. in 1981 for establishing potential causality is applied examining possible mechanisms of action. A guide for clinicians about the rationale of these observations when dealing with patients with uveitis is provided.

EXPERT OPINION

Several agents with different routes of administration (systemic, topical and/or intraocular) may cause intraocular inflammation. The mechanism behind ocular inflammation is frequently unknown. Clinicians should be aware of the potential drug effect to optimize diagnosis and management of such patients.

Intravitreal injection of therapeutic agents

BACKGROUND

Intravitreal injection (IVI) with administration of various pharmacological agents is a mainstay of treatment in ophthalmology for endopthalmitis, viral retinitis, age-related macular degeneration, cystoid macular edema, diabetic retinopathy, uveitis, vascular occlusions, and retinal detachment. The indications and therapeutic agents are reviewed in this study.

METHODS

A search of the English, German, and Spanish language MEDLINE database was conducted. A total of 654 references spanning the period through early 2008 were individually evaluated.

RESULTS

The advantage of the IVI technique is the ability to maximize intraocular levels of medications and to avoid the toxicities associated with systemic treatment. Intravitreal injection has been used to deliver several types of pharmacological agents into the vitreous cavity: antiinfective and antiinflammatory medications, immunomodulators, anticancer agents, gas, antivascular endothelial growth factor, and several others. The goal of this review is to provide a detailed description of the properties of numerous therapeutic agents that can be delivered through IVI, potential complications of the technique, and recommendations to avoid side effects.

CONCLUSION

The IVI technique is a valuable tool that can be tailored to the disease process of interest based on the pharmacological agent selected. This review provides the reader with a comprehensive summary of the IVI technique and its multitude of uses.

Intraocular Properties of An Alkoxyalkyl Derivative of Cyclic 9-(S)-(3-Hydroxyl-2-Phosphonomehoxypropyl) Adenine, An Intravitreally Injectable Anti-HCMV Drug in Rabbit and Guinea Pig

PURPOSE

The aim of this study was to investigate intraocular properties and determine the highest nontoxic dose of hexadecyloxypropyl-cyclic-HPMPA (HDP-cHPMPA), a novel, potent, intravitreally injectable, slow-releasing crystalline drug for long-acting treatment of cytomegalovirus (CMV) retinitis.

METHODS

Various concentrations of HDP-cHPMPA were first studied in vitro in a human foreskin fibroblast (HFF) cell line infected with human cytomegalovirus (HCMV) to determine the EC50. In vivo, 9 pigmented rabbits and 3 doses (55, 100, and 550 microg/eye) were tested in triplicate in 1 eye of each animal. The eyes were monitored with slit lamp, tonopen, indirect ophthalmoscopy, electroretinography (ERG), and histology. A confirmation toxicity study with the dose equivalent to the highest nontoxic dose in rabbit was performed in 9 guinea pig eyes (a second species) to study the potential adverse effect on intraocular pressure (IOP).

RESULTS

In vitro testing in HFF cells showed an EC50 against HCMV of 0.02 microM, which is 75- and 60-fold greater than that of ganciclovir and cidofovir, respectively. All eyes injected with 550 microg/eye and 1 eye injected with 100 microg/eye of HDP-cHPMPA showed toxicity clinically (e.g., vitreous cells, disc edema, and retinal inflammation) as well as histologically (e.g., inflammatory cells in iris, vitreous, and retinal layers with disorganization). None of the eyes injected with 55 microg/eye of HDP-cHPMPA showed toxicity clinically (including ERG) and histologically. The equivalent dose (9.2 microg/eye) in the guinea pig eyes did not show toxicity either, including IOP evaluation (P > 0.05 at all time points after injection).

CONCLUSIONS

Intravitreal injection of the highest nontoxic dose of 55 microg/eye of HDP-cHPMPA in rabbit eyes yields a calculated intravitreal concentration of 65 microM, which is 3250-fold greater than the EC50 against HCMV (0.02 microM). Also, it does not cause hypotony in rabbit and guinea pig eyes and has a vitreous residence time of over 4 months.

Long-term Study of Intraocular Pressure Changes in Patients with Human Immunodeficiency Virus Treated with Highly Active Antiretroviral Therapy

PURPOSE

To characterize a longitudinal relationship between highly active antiretroviral therapy immune recovery as defined by an increase in CD4 cell counts and any associated changes in intraocular pressure (IOP) in both patients with and patients without a history of cytomegalovirus (CMV) retinitis and to determine if human immunodeficiency (HIV)-induced reduction in IOP is reversible.

DESIGN

Retrospective analysis of patient data collected from 1997 through 2004.

PARTICIPANTS

Cohort of patients from one eye center, including patients from the Longitudinal Study of Ocular Complications of Acquired Immunodeficiency Syndrome.

METHODS

Linear regression analyses were conducted within the CMV and non-CMV groups to determine the change in IOP per 100-unit change in CD4 count. Average changes in IOP per change in CD4 count were compared between the CMV and the non-CMV groups using a Wilcoxon rank-sum test. Linear regression analyses were conducted within the CMV and non-CMV groups to determine the linear relationship between the 12-month change in IOP per 12-month 100-unit change in CD4 count.

MAIN OUTCOME MEASURE

Intraocular pressure in relation to changes in CD4 cell counts.

RESULTS

Compared with the non-CMV group, the median IOP change per change in CD4 count was not statistically different from the CMV group (0.9 vs. 1.7 mmHg/100 CD4 cells, respectively; P = 0.20). Analysis of the linear relationship between the 12-month change in IOP and the 12-month change in CD4 count within both the CMV and non-CMV groups showed a strong linear relationship: 67% of the variability in a 12-month IOP change for the CMV group (P<0.0001) and 36% of the variability in a 12-month IOP change for the non-CMV group (P<0.001).

CONCLUSIONS

Reduction in T-lymphocyte count in HIV infection is accompanied by a decrease in IOP in both CMV-infected and non-CMV-infected eyes, and immune recovery is associated with an increase in IOP.

Characterization of a novel intraocular drug-delivery system using crystalline lipid antiviral prodrugs of ganciclovir and cyclic cidofovir

PURPOSE

In an earlier study, a novel intraocular drug-delivery system was reported in which hexadecyloxypropyl-phospho-ganciclovir (HDP-P-GCV) was used as a prototype. The hypothesis was that many biologically effective compounds could be modified to crystalline lipid prodrugs and could be delivered directly into the vitreous in a long-lasting, slow-release form. This study was undertaken to characterize this new drug-delivery system further, by using small particles of HDP-P-GCV and hexadecyloxypropyl-cyclic cidofovir (HDP-cCDV).

METHODS

HDP-P-GCV was microfluidized into 4.4-microm (median) particles, injected into rabbit vitreous. The vitreous drug level was then measured at different time points. Crystalline HDP-cCDV was synthesized, suspended in 5% dextrose, and injected into the rabbit's vitreous at 10, 55, 100, 550, or 1000 microg in 50 microL vehicle per eye, to determine the highest nontoxic dose. The dose, 100 microg, was injected into 24 rabbit eyes, to evaluate pharmacokinetics; into 14 rabbit eyes with established HSV retinitis, to evaluate its efficacy; and into 58 rabbit eyes before herpes simplex virus (HSV) infection to evaluate its intraocular antiviral duration.

RESULTS

Microfluidized particles of HDP-P-GCV showed an increased drug release rate compared with the large-particle drug formulation, with area under concentration-time curve (AUC) of 219.8 +/- 114.1 (n=3) versus 108.3 +/- 47.2 (n=3) for unmodified HDP-P-GCV during the 12-week period after a 2.8-micromole intravitreal injection. There was a 103% increase of the drug released from the microfluidized formulation of HDP-P-GCV versus the unmodified formulation. Intravitreal injections of HDP-cCDV at doses of 100 microg/eye or lower were not toxic. After the 100 microg/eye injections, HPLC analysis showed a vitreous HDP-cCDV level of 0.05 microM at week 5, which declined to 0.002 microM at week 8. The concentration at week 8 (0.002 microM) remained above the IC50 for cytomegalovirus (0.0003 microM). The pretreatment study demonstrated an antiviral effect that lasted 100 days after a single intravitreal injection.

CONCLUSIONS

This crystalline lipid prodrug intravitreal delivery system is an effective approach to achieving sustained, therapeutic drug levels in the eye. Small microfluidized particles of HDP-P-GCV provide more rapid dissolution and higher vitreous drug levels.

Clinical potential of the acyclic nucleoside phosphonates cidofovir, adefovir, and tenofovir in treatment of DNA virus and retrovirus infections

The acyclic nucleoside phosphonates HPMPC (cidofovir), PMEA (adefovir), and PMPA (tenofovir) have proved to be effective in vitro (cell culture systems) and in vivo (animal models and clinical studies) against a wide variety of DNA virus and retrovirus infections: cidofovir against herpesvirus (herpes simplex virus types 1 and 2 varicella-zoster virus, cytomegalovirus [CMV], Epstein-Barr virus, and human herpesviruses 6, 7, and 8), polyomavirus, papillomavirus, adenovirus, and poxvirus (variola virus, cowpox virus, vaccinia virus, molluscum contagiosum virus, and orf virus) infections; adefovir against herpesvirus, hepadnavirus (human hepatitis B virus), and retrovirus (human immunodeficiency virus types 1 [HIV-1] and 2 [HIV-2], simian immunodeficiency virus, and feline immunodeficiency virus) infections; and tenofovir against both hepadnavirus and retrovirus infections. Cidofovir (Vistide) has been officially approved for the treatment of CMV retinitis in AIDS patients, tenofovir disoproxil fumarate (Viread) has been approved for the treatment of HIV infections (i.e., AIDS), and adefovir dipivoxil (Hepsera) has been approved for the treatment of chronic hepatitis B. Nephrotoxicity is the dose-limiting side effect for cidofovir (Vistide) when used intravenously (5 mg/kg); no toxic side effects have been described for adefovir dipivoxil and tenofovir disoproxil fumarate, at the approved doses (Hepsera at 10 mg orally daily and Viread at 300 mg orally daily).

Safety of intravitreous fomivirsen for treatment of cytomegalovirus retinitis in patients with AIDS

PURPOSE

To report data regarding the safety of intravitreous fomivirsen for treatment of cytomegalovirus (CMV) retinitis in patients with acquired immunodeficiency syndrome (AIDS).

DESIGN

Critical review of safety data from three randomized controlled clinical trials with supplemental information from an expanded drug access program.

METHODS

Adverse ocular events reported by clinician investigators were listed using terms modified from the COSTART dictionary. Data for two doses (165-microg/injection [35 eyes, 30 patients] and 330-microg/injection [153 eyes, 120 patients]) and two 330-microg/injection dose schedules of different intensity were pooled to calculate incidence rates for each event. Rates were calculated as "events/patient-year" (based on total cumulative reported events and duration of treatment) for events that could recur during treatment. Rates were calculated as "patients with events/person-year" for the following events: retinal detachment, cataract, visual field disturbance, and retinal pigment epitheliopathy. To assess the ability to manage events, we reviewed treatments given for two events (anterior chamber inflammation, increased intraocular pressure) in one trial. We also report an analysis comparing the proportion of eyes that developed one or more key events to the cumulative number of injections.

RESULTS

Incidence rates were dose and schedule dependent (165 microg/injection, 4.06 events/patient-year; 330 microg/injection, 6.58 events/patient-year [less intense regimen] and 8.35 events/patient-year [more intense regimen]). The most frequently reported events were anterior chamber inflammation and increased intraocular pressure. We found no evidence that the proportion of patients with events increased as the number of injections increased.

CONCLUSIONS

Intravitreous fomivirsen is well tolerated with an acceptable safety profile. Adverse ocular events associated with doses and schedules used clinically can be managed successfully with medical therapy.

Treatment of severe ocular hypotony in AIDS patients with cytomegalovirus retinitis and cidofovir-associated uveitis

OBJECTIVE

To describe the medical treatment of severe ocular hypotony in HIV-seropositive patients with cytomegalovirus retinitis and cidofovir-associated uveitis.

PATIENTS AND METHODS

Two HIV-seropositive patients with cytomegalovirus retinitis and cidofovir-associated uveitis complicated by severe ocular hypotony were unresponsive to conventional therapy after treatment with cidofovir was stopped. They were subsequently treated successfully with ibopamine 2% eyedrops and dexamethasone 0.1% eyedrops.

RESULTS

In both cases, an increase in intraocular pressure to normal values was observed on average 18.5 days after starting treatment. Intraocular pressure remained stable while on therapy for a mean follow-up of 9.5 months. During the follow-up period, any attempt to stop treatment was followed by an intraocular pressure decrease; conversely, restoration of therapy increased intraocular pressure to normal values. No reactivation of cidofovir-associated uveitis or cytomegalovirus retinitis was observed during the follow-up period.

CONCLUSIONS

Ibopamine 2% eyedrops in combination with dexamethasone 0.1% eyedrops is a satisfactory therapy for severe ocular hypotony in patients with cytomegalovirus retinitis and cidofovir-associated uveitis.

Uveitis in patients treated with intravenous cidofovir

PURPOSE

To study the characteristics of uveitis occurring during intravenous cidofovir treatment for CMV retinitis in patients with AIDS.

PATIENTS AND METHODS

We retrospectively studied ten cases (16 eyes) of uveitis in patients with CMV retinitis treated with intravenous cidofovir. All the patients had ophthalmologic examinations and, if required, fundus angiographies. The median follow-up was eight months.

RESULTS

Uveitis occurred after a mean of 8.5 infusions of cidofovir (range 2-17). All ten patients were on protease inhibitors. The mean CD4+ cell count was 92 +/- 51/microl and the median viral load was 3.9 log. All the eyes with uveitis had healed CMV retinitis. The first examination of the involved eyes showed inflammation of the anterior chamber (100%), vitritis (50%), posterior synechiae (75%), and low intraocular pressure (94%). Uveitis did not relapse in the seven patients who stopped cidofovir, whereas it relapsed in two of the three patients who did not stop treatment. At the end of follow-up, permanent posterior synechiae were present in 69% of the involved eyes.

COMMENTS

Cidofovir therapy necessitates slit-lamp surveillance, especially in patients on HAART. Cidofovir-related uveitis requires a local steroid treatment, but if possible, cidofovir should be withdrawn.

Anterior uveitis associated with intravenous cidofovir use in patients with cytomegalovirus retinitis

AIM

Intravenous cidofovir is used to treat cytomegalovirus (CMV) retinitis, and has been reported to cause anterior uveitis. Relations were sought between this complication and patient characteristics that might help predict its occurrence.

METHODS

17 patients with AIDS and CMV retinitis who were treated with intravenous cidofovir were identified, and the following data collected in a retrospective chart review: demographic characteristics, duration of CMV retinitis, retinal lesion characteristics, dose and duration of cidofovir therapy, tests of renal function, CD4+ T lymphocyte counts, visual acuity, intraocular pressure, iris colour, history of diabetes mellitus, and use of concomitant medications. Case-control analyses were performed to determine risk factors for developing cidofovir associated uveitis.

RESULTS

Anterior uveitis characterised by pain, ciliary injection, and decreased visual acuity occurred in 10 patients (59%). Median interval to development of uveitis was 11 doses of cidofovir. Symptoms developed 4.4 (SD 2.5) days (median 3.5) after an infusion of cidofovir. Patients who developed uveitis had a significantly greater rise in CD4+ T lymphocyte count while receiving cidofovir (68.4 (75.7) x10(6)/l versus 5.0 (0.6) x10(6)/l, (p = 0.04)). By stepwise linear regression, this factor accounted for 33% (p = 0.03) of the effect of developing uveitis. Mean follow up time, intraocular pressure decline during cidofovir therapy, serum creatinine and urine protein concentrations, and rates of protease inhibitor use were not significantly different between patients who developed uveitis and those who did not. Uveitis responded to topical corticosteroids and cycloplegia.

CONCLUSION

Anterior uveitis in patients receiving intravenous cidofovir therapy may be related to improving immune function. The uveitis responds to treatment and may not preclude continuation of cidofovir.

Comparative tolerability of therapies for cytomegalovirus retinitis

Cytomegalovirus (CMV) retinitis is a potentially sight-threatening complication of advanced HIV infection. The acute infection can be controlled with one of several therapies, including intravenous ganciclovir, foscarnet or cidofovir, slow release ganciclovir intraocular implants or serial intraocular injections of ganciclovir or foscarnet. The initial induction course of therapy is typically followed by lifelong maintenance therapy. In addition to the aforementioned treatments, oral ganciclovir and intravitreal fomivirsen injections are other options for maintenance therapy. The choice of agent must take into consideration factors such as comparative short and long term toxicity of the agents, route of administration and the possible need for indwelling catheters, administration time, cost and protection afforded against systemic dissemination of CMV infection. Possible drug interactions and additive toxicities of other agents needed for the management of the underlying HIV infection must also be taken into consideration. These factors can affect the tolerability of therapy as well as the quality of life of the patient. Relapse or progression of CMV retinitis may be caused by either inadequate drug concentrations at the site of the infection or by drug resistance. This may necessitate either an increase in drug dosage, a change in route of administration or a change to an alternative agent. All of these approaches can increase the risk of toxicity of the therapy. With the initiation of highly active antiretroviral therapy and partial reconstitution of the immune system, some patients have been able to successfully discontinue anti-CMV maintenance therapy, thereby decreasing long term drug toxicity. Determination of the patient predictors of success of this approach is an active area of research.

Changing trends in cytomegalovirus retinitis with triple therapy

PURPOSE

Cytomegalovirus retinitis (CMVR) has been the most common cause of visual loss in AIDS patients. We investigate whether the pattern of disease has changed since the introduction of triple therapy.

METHODS

We reviewed the records of all patients with CMVR in one teaching hospital HIV unit over a 2 year period (n = 24). This included the opthalmic and systemic findings, HIV and CMV treatment, survival after diagnosis and CD4 results.

RESULTS

There has been a marked decrease in the number of patients developing new CMVR: from 21 eyes (15 patients) to 4 eyes (4 patients) in two consecutive 12 month periods between January 1996 and December 1997, coinciding with the introduction of triple therapy in October 1996. Median survival has increased from 376 days in the deceased patients to 598 days in the survivors on triple therapy. Median time to CMVR relapse has lengthened from 79 to 179 days in the triple therapy cohort. The pattern of ocular morbidity in the 11 eyes of the 7 surviving patients is also changing, with no new zone 1 disease, and a marked rise in the incidence of uveitis, maculopathy and cataracts.

CONCLUSION

Results suggest that triple therapy is associated with an increase in survival, a decrease in CMVR relapse and changes in ocular features. This transition has implications for current screening and treatment protocols.

Ocular complications of intravenous cidofovir for cytomegalovirus retinitis in patients with AIDS

PURPOSE

To describe the frequency of anterior uveitis and ocular hypotony in cidofovir-treated patients with acquired immune deficiency syndrome (AIDS)-related cytomegalovirus (CMV) retinitis.

METHODS

A retrospective review was performed of all patients with AIDS-related CMV retinitis during a 12-month period. The CMV retinitis activity, concurrent illnesses and medications, and CD4+ lymphocyte count were recorded in addition to the degree of anterior chamber inflammation and intraocular pressure at each visit. The frequency of uveitis and ocular hypotony in cidofovir-treated patients was determined and the possible influence of other ocular and systemic factors considered.

RESULTS

Eight of 9 patients on cidofovir developed anterior uveitis. The cellular anterior chamber activity resolved with topical corticosteroid administration in all eyes with uveitis but significant flare persisted despite topical steroids in 3 patients. Posterior synechiae responded poorly to topical mydriatic therapy, resulting in inadequate mydriasis which significantly limited the fundal view. One patient developed a visually significant unilateral hypotonous maculopathy.

CONCLUSIONS

Patients treated with intravenous cidofovir for AIDS-related CMV retinitis are at significant risk of ocular adverse effects. Prompt treatment with topical corticosteroids and mydriatics may control uveitis and in some cases cidofovir treatment may be cautiously continued. In the event of ocular hypotony cidofovir should be discontinued in favour of an alternative anti-cytomegaloviral agent.

Fluorophotometry in patients with human immunodeficiency virus with and without cytomegalovirus retinitis

OBJECTIVE

To study the aqueous humor dynamics in subjects with human immunodeficiency virus (HIV) with and without cytomegalovirus (CMV) retinitis.

DESIGN

Prospective cross-sectional study.

PARTICIPANTS

Fourteen HIV-positive subjects (27 eyes, 19 with CMV retinitis and 8 without CMV retinitis), and a control group of 9 HIV-negative subjects (17 eyes).

TESTING

Fluorophotometry.

MAIN OUTCOME MEASURES

Aqueous flow rates as measured by fluorophotometry and intraocular pressure (IOP).

RESULTS

Analysis of variance of the mean corrected aqueous flow rate revealed that both HIV-positive groups had significantly lower aqueous flow rates than did the control group (P < 0.03). No difference in mean aqueous flow rates was found between the HIV-positive eyes with or without CMV retinitis. Comparison of mean IOP revealed that HIV-positive eyes with CMV retinitis had significantly lower IOP than did the HIV-positive eyes without CMV retinitis (P = 0.03) and HIV-negative subjects (P = 0.002). There was no correlation between aqueous flow rate and IOP in HIV-positive subjects (P > 0.5).

CONCLUSION

The lack of correlation between the aqueous flow rate and IOP suggests that there may be some disassociation between these parameters in HIV-positive patients. Further studies are needed to better understand the mechanism of aqueous formation and in the management of disorders affecting IOP in this population.

Low-dose intravitreal cidofovir (HPMPC) therapy of cytomegalovirus retinitis in patients with acquired immune deficiency syndrome

PURPOSE

The authors have shown that long-term treatment of cytomegalovirus (CMV) retinitis with 20-microgram intravitreal injections of cidofovir (HPMPC) is highly effective but may be associated with iritis and profound hypotony. They evaluated the efficacy and safety of 10-microgram intravitreal injections of cidofovir and made comparisons with their findings of 20-microgram injections.

METHODS

The current study was conducted as a nonrandomized consecutive case series at the AIDS Ocular Research Unit of the University of California at San Diego. Twenty-seven eyes of 18 patients were injected with 10 micrograms intravitreal cidofovir and had complete follow-up. These were compared with another consecutive series of 24 eyes of 17 patients injected with 20 micrograms of cidofovir.

MAIN OUTCOME MEASURES

The main outcome in this study was the incidence of failure to respond to treatment with 10-microgram injections. The authors also compared the time to progression of CMV retinitis after the initial intravitreal injections of 10 micrograms and 20 micrograms of cidofovir. Secondary outcomes included incidence of iritis and changes in intraocular pressure (IOP) after cidofovir injections.

RESULTS

The median time to retinitis progression was 45 days after a single intravitreal injection of 10 micrograms cidofovir compared with 55 days with the authors' series of 20-microgram injections. This difference was statistically significant (P = 0.033, log-rank test) and appeared to be due principally to a 26% incidence of primary failure in the 10-microgram group (progression > or = 750 microns within 28 days, P = 0.0017 Wilcoxon test). Progression after a second injection of 10 micrograms cidofovir was more rapid (32 days, P = 0.037). The incidence of iritis after 10-microgram injections was 2.2% compared with 23% with 20-microgram injections (P = 0.003, Fisher's exact test, two-tailed). There was less decrease in IOP between the baseline injection and subsequent visits in the 10-microgram group.

CONCLUSIONS

Treatment of CMV retinitis with 10-microgram intravitreal cidofovir injection was not as effective as with 20 micrograms and may allow development of drug resistance, but there were fewer side effects with the 10-microgram dose. The drug appears to have a narrow therapeutic index, and other attempts at reducing the side effects while preserving the long-acting effect, such as liposome delivery, may be warranted.