The Effect of Amantadine on Corneal Endothelium in Subjects with Parkinson's Disease

Amantadine-induced corneal edema: A case and literature review

Purpose

To present a case of irreversible corneal edema after 10 years of amantadine use. A literature review was carried out to describe the clinical characteristics and outcomes of amantadine-induced corneal edema.

Observations

A 36-year-old woman presented with a 6-week history of gradually progressive bilateral painless visual loss with visual acuity (VA) of 20/350 and 20/300 in the right and left eye, respectively. Examination showed bilateral diffuse central corneal edema with multiple Descemet membrane folds without endothelial guttata, keratic precipitates or intraocular inflammation. This did not respond to hypertonic saline drops and empirical treatment for presumed herpetic endotheliitis with oral acyclovir. Medication review revealed the use of amantadine 100mg daily for the past 10 years, prescribed by her neurologist for fatigue. Despite discontinuing amantadine, corneal edema was irreversible due to a markedly reduced endothelial cell count of 625 (right) and 680 cells/mm2 (left).

Conclusions and Importance

This case highlights the need to consider amantadine as a cause of unexplained bilateral non-guttae corneal edema. A literature review of 33 case reports revealed broadly similar features of amantadine-induced corneal edema; whilst most cases had favorable outcomes with median VA 20/25 (interquartile range IQR 20/20-20/30) and complete resolution of corneal edema within 30 days (IQR 14-35) of amantadine discontinuation, most experienced low endothelial cell density 759 cells/mm2 (IQR 621-1078). Taken together, screening specular microscopy ought to be considered for those in whom amantadine is likely required long-term.

Dry eye in Parkinson's disease: a narrative review

In Parkinson's disease (PD) patients, a wide range of ocular and visual disorders are present. Tear film instability, inflammation and dysfunction of the ocular surface, and the presence of symptoms of visual disturbance characterize dry eye, a multifactorial disease of the ocular surface. Based on a literature search, we discuss the frequency, pathogenesis, and influence on the quality of life of patients with dry eye in Parkinson's disease. Furthermore, we review the available means of diagnosis and management of dry eye. An improvement in awareness and recognition of dry eye is needed to provide suitable, personalized therapeutic options for PD patients, aiming to improve their quality of life, independence, and safety.

Ocular Surface Features in Patients with Parkinson Disease on and off Treatment: A Narrative Review

Parkinson disease (PD) is a progressive, neurodegenerative disease of the central nervous system. Visual disturbance is one of the most frequent nonmotor abnormalities referred to by patients suffering from PD at early stages. Furthermore, ocular surface alterations including mainly dry eye and blink reduction represent another common finding in patients with PD. Tears of PD patients show specific alterations related to protein composition, and in vivo confocal microscopy has demonstrated profound changes in different corneal layers in this setting. These changes can be attributed not only to the disease itself, but also to the medications used for its management. In particular, signs of corneal toxicity, both at epithelial and endothelial level, are well described in the literature in PD patients receiving amantadine. Management of PD patients from the ophthalmologist's side requires knowledge of the common, but often underdiagnosed, ocular surface alterations as well as of the signs of drug toxicity. Furthermore, ocular surface biomarkers can be useful for the early diagnosis of PD as well as for monitoring the degree of neural degeneration over time.

Amantadine therapy for Parkinson's Disease: In Vivo Confocal Microscopy corneal findings, case report and revision of literature

BACKGROUND

To report a case of a patient showing bilateral corneal opacities after amantadine chronic treatment for Parkinson's Disease (PD) and corneal edema associated with intra-epithelial and -endothelial depositions. After amantadine discontinuation a complete clinical remission with only a partial ultrastructural corneal recovery was reported.

CASE PRESENTATION

We describe a 78-year-old man with non-medical-responding bilateral corneal edema in treatment with systemic Amantadine for PD. In vivo confocal Microscopy (IVCM) analysis revealed hyperreflective particles at the epithelial level and expanded hyperreflective keratocyte and a disarrangement of stromal lamellae; endothelial cells showed hyperreflective intracellular inclusions in central and in peripheral areas with central polymegatism and pleomorphism. After 1 and 6 months the amantadine discontinuation, the absence of bilateral corneal edema and opacities were noted at the slit lamp examination, associated with the disappearance of epithelial and stromal abnormalities, but the persistence of endothelial hyperreflective deposits with a pleomorphism and polymegatism worsening at the IVCM exam.

CONCLUSION

The evaluation of a patient's cornea 6 months after the discontinuation of systemic amantadine therapy showed a clinical complete remission, with a complete resolution of the bilateral corneal oedema. On the other hand, ultrastructurally, amantadine toxicity is a completely reversible phenomenon at the epithelial level; conversely IVCM showed persistent endothelial degradation.

Corneal Endothelium: A Promising Quantitative Index for Graves Ophthalmopathy Activity Evaluation

PURPOSE

To investigate the corneal endothelium damage in Graves ophthalmopathy (GO) and its role as a promising quantitative index to evaluate GO activity.

DESIGN

Cross-sectional study.

METHODS

This study included 128 eyes of 64 patients with GO. All subjects underwent ophthalmologic examinations, including proptosis, tear break-up time (BUT), corneal fluorescein staining, and Schirmer test. Corneal endothelium was measured by noncontact specular microscope and ocular biometric parameters were measured by IOLMaster 700. Each eye was assigned a specific clinical activity score (CAS), then grouped as active (CAS ≥3 points) or inactive (CAS <3 points). Ocular parameters between the 2 groups were compared using generalized estimating equations accounting for inter-eye correlation, and receiver operating characteristic (ROC) curves were also obtained. Main outcome measures were parameters of corneal endothelium.

RESULTS

Among the included eyes, 81 eyes had inactive GO and 47 eyes had active GO. Corneal endothelial cell morphology was altered in active GO compared with inactive GO. The coefficient variation of cell area (CV) was significantly higher in active GO compared with inactive GO (37.0 [34.4-41.2]% vs 33.9 [30.9-36.8]%, P = .001), and positively correlated with CAS (r = 0.322, P < .001). Moreover, CV showed a diagnostic capacity to differentiate the active eyes from inactive eyes. The area under the ROC curve was 0.705.

CONCLUSIONS

Active GO had morphologic changes in corneal endothelium compared with inactive GO. CV is a sensitive indicator to reflect corneal endothelial function, and has the potential to be adopted as a noninvasive, objective, and quantitative index for evaluating the activity status of GO patients.

[Amantadine in the treatment of Parkinson's disease. New opportunities in the context of COVID-19]

The article presents data from recent studies on the mechanisms of action and clinical efficacy of amantadines, and also describes a possible protective effect against COVID-19.

Amantadine can induce intra-epithelial deposition in the cornea

Purpose

Amantadine has been reported to cause various corneal complications, such as superficial punctate keratitis, corneal endothelial dysfunction, and corneal edema. However, there have been no reports of amantadine-induced deposits in the corneal epithelium. Here, we describe the first case with amantadine-induced deposits in the corneal epithelium proved by confocal biomicroscopy.

Observations

An 81-year-old woman presented with impaired vision in both eyes. She had been treated with amantadine for 9 years. Corrected visual acuity was 0.8 in both eyes. Furthermore, both eyes showed opacities in the corneal epithelial corneal layer. On confocal biomicroscopy, there were highly reflective deposits in corneal epithelial cells. There were no pathological findings in the stroma and endothelium. Two months after discontinuation of amantadine, corneal opacities disappeared, and visual acuity was 1.0 in both eyes.

Conclusions

Administration of amantadine can cause deposits in corneal epithelial cells.

Evaluation of corneal sublayers thickness and corneal parameters in patients with Parkinson's disease

PURPOSE

The aim of this study was to compare the blink rate (BR), tear tests, corneal parameters, and the thickness of each corneal sublayer in patients with Parkinson's disease (PD) and healthy individuals.

METHODS

A total of 64 eyes from 64 patients with PD and 64 eyes from 64 age- and sex-matched healthy individuals were included in this study. All participants underwent a detailed neurological and ophthalmological evaluation. The severity of disease was measured according to Hoehn-Yahr (H-Y) scale. The blink rate (BR), Schirmer test, and tear break-up time (TBUT) scores were assessed. Corneal parameters were measured using Pentacam. Additionally, the thickness of the corneal epithelium, Bowman layer, stroma, and Descemet membrane-endothelium complex were measured on the central cornea with anterior segment module of spectral domain optical coherence tomography (AS-OCT).

RESULTS

The BR, Schirmer's test, TBUT, pachymetric measurements, Bowman layer, and stromal thickness values of the patient group were significantly lower than those of the control group. The disease duration and disease severity were significantly negative correlated with the pachymetric measurements and stromal thickness. Also, the values of TBUT and the score of Schirmer test were significantly positive correlated with the pachymetric measurements and stromal thickness.

CONCLUSIONS

A reduced BR and poor tear quality in the PD, can result in reduced pachymetric measurements and stromal thickness.

Fuchs endothelial corneal dystrophy and corneal endothelial diseases: East meets West

Fuchs endothelial corneal dystrophy (FECD) is amongst one of the most common indications for endothelial keratoplasty worldwide. Despite being originally described among Caucasians, it is now known to be prevalent among a large number of populations, including Asians. While the FECD phenotype is classically described as that of central guttate and pigment deposits associated with corneal endothelial dysfunction, there are subtle yet important differences in how FECD and its phenocopies may present in Caucasians vs Asians. Such differences are paralled by genotypic variations and disease management preferences which appear to be geographically and ethnically delineated. This article provides a succinct review of such differences, with a focus on diagnostic and management issues which may be encountered by ophthalmologists practicing in the different geographic regions, when evaluating a patient with FECD.

Amantadine-Induced Corneal Edema in a Pediatric Neuro-Oncology Patient: A Case Report

Amantadine is commonly prescribed as a neurostimulant in patients with brain injuries. This is a case of a 14-year-old male with a history of brain tumor that developed corneal edema after initiation of amantadine, a rare but documented side effect of this medication. After discontinuation of amantadine, the corneal edema resolved within two months, but endothelial cells density remained low. LEVEL OF EVIDENCE: V.

Efficacy and safety of amantadine for the treatment of L-DOPA-induced dyskinesia

L-DOPA induced dyskinesias (LIDs) may affect up to 40% of Parkinson's disease (PD) and impact negatively health-related quality of life. Amantadine has demonstrated significant antidyskinetic effects in animal PD models and in randomized double-blind placebo-controlled trials (RCTs) in patients with PD. These effects are thought to be related to the blockade of NMDA receptors modulating cortico-striatal glutamatergic-dopaminergic interactions involved in the genesis of LIDs. There are three pharmaceutical forms of amantadine currently available in the market: an oral immediate-release (IR) formulation, which is widely available; an extended-release (ER) formulation (ADS-5102) which has been recently developed and approved by the FDA; and an intravenous infusion (IV) solution, which is not commonly used in clinical practice. RCTs with amantadine IR or ER, involving more than 650 patients have shown consistent and long-lasting reductions in LIDs. Interestingly, ADS-5102 not only reduced LIDs, but also reduced significantly at the same time the duration of daily OFF-time, a unique finding compared with other antiparkinsonian medications that usually reduce time spent OFF at the cost of worsening of LIDs. Amantadine IR might also have possible effects on other PD symptoms such as apathy or fatigue. The most common adverse reactions with amantadine are constipation, cardiovascular dysfunction including QT prolongation, orthostatic hypotension and edema, neuropsychiatric symptoms such as hallucinations, confusion and delirium, nausea and livedo reticularis. Corneal degeneration is rare but critical. In summary, amantadine immediate and extended-release are effective and safe for the treatment of LIDs.

Acute corneal edema without epithelium compromise. A case report and literature review

El edema de córnea es una entidad que se produce por un gran número de causas y tiene diversas formas de presentación y diferentes grados de afección. En este artículo se reporta el caso de un hombre con edema de córnea agudo sin compromiso epitelial, en el que el cuadro clínico, el examen oftalmológico y los estudios de extensión no lograron establecer su etiología. Además, se hace una revisión de la literatura disponible respecto a todas las posibles causas de edema de córnea agudo, agrupándolas en aquellas que ocasionan el edema por lesión o inflamación epitelial o estromal, por disfunción endotelial o por un aumento en la presión intraocular.

Amantadine Use as a Risk Factor for Corneal Edema: A Nationwide Cohort Study in Taiwan

PURPOSE

To evaluate the association between amantadine use and corneal toxicity in a nationwide population.

DESIGN

Retrospective cohort study of nationwide population-based administrative database.

METHODS

This study analyzed data in the Taiwan Longitudinal Insurance Database for a group of 8195 patients diagnosed with Parkinson disease during a 15-year period (January 1, 1996 to December 31, 2010). A control group of 8195 patients without Parkinson disease was randomly matched with the Parkinson group by age, sex, and comorbidity index. The Kaplan-Meier method was used to calculate the cumulative incidence of corneal edema. Incident rate ratios and Cox proportional hazard regressions were estimated to compare the risk of corneal edema. The same methods were then used to compare the risk between patients with and without amantadine treatment.

RESULTS

The incidence of corneal edema in the Parkinson group (123 patients; 1.50%) was significantly higher than that in the control group (82 patients; 1.0%) (P = .004). The incidence ratio for corneal edema in the Parkinson group vs the controls was 5.77. When the Parkinson group was further subgrouped by use and non-use of amantadine, the hazard ratio for corneal edema was 1.79 times higher in the amantadine subgroup. Analyses of the amantadine subgroup by cumulative dose revealed that the 30-day hazard ratio for corneal edema was 2.05 higher in patients given moderate doses (2000-4000 mg) of amantadine and 2.84 times higher in the subgroup of patients given high doses (>4000 mg).

CONCLUSIONS

Amantadine increases the risk of corneal edema in a dose-dependent manner.

The effect of systemic amantadine sulfate on malondialdehyde and total thiol levels in rat corneas

Purpose:

To evaluate the malondialdehyde (MDA) and total thiol (sulfhydryl, SH) levels in rat corneas after intraperitoneal injection of amantadine sulfate.

Methods:

A total of 12 Wistar albino rats were divided into two groups: control group (n = 6) and amantadine group (n = 6). Balanced salt solution (1 mL, 0.9% NaCl, twice/day) was injected into rats in control group. Amantadine sulfate (2 mg/1 mL, twice/day) was injected into rats in amantadine group. In each group, two rats were injected for 1 week, two received injections for 1 month, and two rats received injections for 3 months. The corneas were homogenized and MDA and SH levels were measured spectroflourometrically.

Results:

In control group, median MDA and SH levels were 2.37 (range, 0.92-3.60) and 25.35 (range, 6.30-54.0) nmol/mg, respectively. In amantadine group, median MDA and SH levels were 3.57 (range, 1.25-5.92) and 32.65 (range, 3.30-48.3) nmol/mg, respectively. The difference between this two groups regarding MDA (P = 0.14) and SH (P = 1.0) levels was statistically insignificant.

Conclusion:

Systemically administered amantadine sulfate seems not to cause MDA and SH imbalance in rat corneas.

Ocular side effect of tinidazole: a rare case report

Ocular side effects in the form of punctate epithelial erosions with the use of tinidazole - a 5-nitroimidazole group of drugs is very rare. A 32-year-old male was prescribed tablet tinidazole for the treatment of amoebiasis but developed adverse effects in the form of blisters on both upper and lower lips with itching and burning sensation, itching and burning on penile and anal area associated with punctate epithelial erosions of cornea of both the eyes. All these are rare manifestations but punctate epithelial erosions of cornea has never been reported in the literature so far. Punctate epithelial erosions of cornea have not previously been reported and should be added to the list of complications of tinidazole. Hence, this case is being reported.

Central corneal thickness and its relationship to Parkinson's disease severity

OBJECTIVE

To investigate the effect of Parkinson's disease (PD) on blink rate (BR), tear breakup time test (TBUT), Schirmer's test, and corneal thickness, and the relationship of these effects with disease severity.

DESIGN

Prospective controlled study.

PARTICIPANTS

Fifty-five eyes from 55 patients with PD and 40 eyes from 40 healthy subjects were analyzed in the study.

METHODS

The patients were divided into 2 groups according to their Hoehn-Yahr (H-Y) scores; patients classified as H-Y 1-2 were designated as the mild group, and those classified as H-Y 3-5 were designated as the moderate group. Subjects were screened for BR, TBUT, and Schirmer's test, and the central corneal thickness (CCT) was measured.

RESULTS

The BR, Schirmer's test, TBUT, and CCT values of the patient group were significantly lower than those of the control group. The BR and TBUT of the mild group were significantly lower than those of the control group, but the decreases in the Schirmer's test values and CCT were not statistically significant. In addition, significant decreases in the BR, TBUT, Schirmer's test scores, and CCT were observed in the patient group as the H-Y score increased.

CONCLUSIONS

A reduced BR and poor tear quality in the early stages of PD, as well as decreased tear production as the disease progresses, can result in reduced CCT. The possibility of a thin cornea should be taken into consideration while measuring the intraocular pressure in patients with severe PD.

Amantadine induced corneal edema in a patient with primary progressive freezing of gait

Amantadine is commonly used for Parkinsonism. However amantadine can induce adverse corneal reaction. Here we report a patient with primary progressive freezing of gait who had severe corneal edema associated with amantadine, which was reversible after discontinuation of the amantadine. This report alerts neurologists for this reversible but potentially critical corneal edema in patients with Parkinsonism who are receiving amantadine.

[Corneal toxicity due to amantadine]

CASE REPORT

A 64 year-old female with Parkinson disease treated with amantadine for two years who suddenly suffered bilateral corneal oedema. It was initially treated as herpetic endotheliitis without improvement as we lacked information on her chronic treatment. The corneal oedema finally resolved after withdrawing the drug.

DISCUSSION

Amantadine hydrochloride may produce endothelial dysfunction. Once the amantadine treatment is stopped, the corneal oedema may be reversible but endothelial density remains low. An ophthalmologist examination should be performed before the initiation of amantadine treatment in order to establish a risk: benefit ratio, especially in those patients with low endothelial density or any endothelial anomaly.