Drug-induced maculopathy

Macular edema after siponimod treatment for multiple sclerosis: a case report and literature review

BACKGROUND

As a modulator of the sphingosine 1-phosphate receptor, siponimod is administered as a therapeutic intervention for multiple sclerosis. A previous phase 3 study first reported siponimod-associated macular edema. Since that report, there were only few relevant reports in clinical settings. Here, we report a case of secondary progressive multiple sclerosis developed macular edema after siponimod treatment. We also review the progress of sphingosine 1-phosphate receptor modulators, elaborate on accepted mechanisms in treating multiple sclerosis, and discuss the causation of siponimod-associated macular edema.

CASE PRESENTATION

A 38-year-old Chinese female patient with secondary progressive multiple sclerosis, who had recurrent numbness of the limbs and right leg fatigue, developed mild macular edema following 4 months of siponimod treatment. The macular edema resolved after discontinuing the medication, and did not recur after resuming siponimod.

CONCLUSION

Although siponimod-associated macular edema may be rare, mild, transitory, and manageable, it cannot be ignored and requires ongoing vigilance.

Foveal photoreceptor disruption in ocular diseases: An optical coherence tomography-based differential diagnosis

Fovea centralis, located at the center of the macula, is packed with cone photoreceptors and is responsible for central visual acuity. Isolated foveal photoreceptor disruption may occur in a variety of hereditary, degenerative, traumatic, and toxic chorioretinal diseases. These have been known previously by multiple synonyms including macular microhole, foveal spot, and outer foveal microdefects. A common clinical feature underlying these conditions is the presence of apparently normal fovea or subtle hypopigmented lesion at the foveal or juxtafoveal area. A detailed history along with high-resolution optical coherence tomography is often helpful to derive a conclusive diagnosis in majority of these cases. Focal photoreceptor disruption usually involves loss or rarefaction of ellipsoid/interdigitation zone, either in isolation or associated with external limiting membrane or retinal pigment epithelium disruption in the fovea. Vitreomacular interface (VMI) disorders including vitreomacular traction, posterior vitreous detachment, epiretinal membrane, and impending macular hole possibly remain the most common cause. Retinal dystrophies such as cone dystrophy, occult macular dystrophy, and achromatopsia may present with diminution of vision and normal appearing fundus in a younger age group. Other causes include photic retinopathy (e.g., from a history of sun gazing, or laser pointer exposure), blunt trauma, drug exposure (e.g., poppers maculopathy or tamoxifen retinopathy), and acute retinal pigment epitheliopathy (ARPE). Visual prognosis depends on the underlying etiology with complete recovery common in the subset of patients with VMI, and ARPE, whereas persistent outer retinal defects are the rule in other conditions. We discuss the differential diagnoses that lead to isolated foveal photoreceptor defects. Identifying and understanding the underlying disease processes that cause foveal photoreceptor disruption may help predict visual prognosis.

Occult retinopathy following treatment of Hepatitis C with glecaprevir/pibrentasvir (Mavyret)

BACKGROUND/PURPOSE

Medication-induced ocular toxicity is an important consideration in the differential diagnosis of unexplained visual disturbance. We present a case of visual disturbance after starting treatment with glecaprevir/pibrentasvir (Mavyret), a therapy for Hepatitis C virus approved by the FDA in 2017.

METHODS

A 50-year-old male with no significant ocular history experienced bilateral visual disturbance, including visual field and acuity loss, shortly after initiating treatment with Mavyret for Hepatitis C. Examination of the anterior and posterior segments was unremarkable, and no abnormalities could be identified on multimodal imaging of the eye and brain, including MRI, SD-OCT, and fundus autofluorescence. Extensive testing for inflammatory, infectious, nutritional, and genetic etiologies for optic neuropathy and retinopathy was negative.

RESULTS

Electrophysiology testing was pursued to narrow the broad differential diagnosis. Full-field electroretinography and multi-focal electroretinography detected deficiencies in the rod and cone visual pathways and attenuated electrophysiologic responses in the fovea. Pattern electroretinography and visually-evoked potentials demonstrated macula dysfunction. Taken together, electrophysiologic data suggested diffuse retinal dysfunction, which was most pronounced in the macula.

CONCLUSIONS

Given the temporal relationship between Mavyret administration and vision loss in our patient, and the absence of an underlying cause after extensive evaluation, we propose that Mavyret may be associated with a toxic occult retinopathy characterized by panretinal dysfunction without clinically apparent structural findings.

Retinal Toxicity Induced by Chemical Agents

Vision is an important sense for humans, and visual impairment/blindness has a huge impact in daily life. The retina is a nervous tissue that is essential for visual processing since it possesses light sensors (photoreceptors) and performs a pre-processing of visual information. Thus, retinal cell dysfunction or degeneration affects visual ability and several general aspects of the day-to-day of a person's lives. The retina has a blood-retinal barrier, which protects the tissue from a wide range of molecules or microorganisms. However, several agents, coming from systemic pathways, reach the retina and influence its function and survival. Pesticides are still used worldwide for agriculture, contaminating food with substances that could reach the retina. Natural products have also been used for therapeutic purposes and are another group of substances that can get to the retina. Finally, a wide number of medicines administered for different diseases can also affect the retina. The present review aimed to gather recent information about the hazard of these products to the retina, which could be used to encourage the search for more healthy, suitable, or less risky agents.