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Project Description

Please note that we are a research service provider, not a pharmacy or clinic, so we are unable to see patients and do not offer diagnostic and treatment services for individuals.

Ocular Histoplasmosis Syndrome (OHS)

Ocular Histoplasmosis Syndrome (OHS) is a chorioretinal disease that incorporates a certain pattern in the posterior segment of the eye as pathological features. We at Protheragen, provide full-spectrum services in diagnostics and therapeutics development for OHS. Our qualified scientists employ advanced technologies to provide innovative diagnostics and therapeutic strategies.

Overview of Ocular Histoplasmosis Syndrome (OHS)

Ocular Histoplasmosis Syndrome (OHS) is a result of multifocal chorioretinal damage, and it occurs almost exclusively in geographic areas where Histoplasma capsulatum is endemic. It has a characteristic fundus appearance that includes features such as peripapillary atrophy (PPA), chorioretinal scarring, which are often called "histo spots", and even choroidal neovascularization (CNV). OHS is one of the important conditions causing central vision loss in young adults within the endemic region, as CNV is the most important pathological feature causing vision loss. Pathogenesis of OHS is very intricate and does involve an infectious component alongside an immunological one, while the range of manifestations is quite broad, from asymptomatic peripheral scarring to potentially severe vision-threatening complications.

Analysis of fundus photographs in ocular histoplasmosis syndrome.

Fig. 1 Fundus photos of the right and left eye (A) and OCT of the macula of the left eye (B). (Janetos T. M., et al., 2023)

Diagnostics Development for Ocular Histoplasmosis Syndrome

Fundus Examination and Imaging
Diagnosis of OHS still relies upon a fundus examination, which involves characteristic PPA findings and other more advanced findings like chorioretinal scarring and CNV. The discovery of newer imaging modalities like SD-OCT has fundamentally altered the diagnosis process by offering intricate images of the retina and choroid's cross sections. SD-OCT helps in accurately determining the position and level of activity of CNV, thereby serving as a fundamental instrument in both practices.
Fluorescein Angiography (FA)
FA is an important imaging technique for the evaluation of CNV and other vascular changes associated with OHS. Through arterial injection of a fluorescent dye, its circulation within the retinal and choroidal vessels can be recorded, allowing the detection of leakage, pooling, and other pathological features suggesting the presence of CNV. It is especially helpful in distinguishing classic from occult CNV.

Indocyanine Green Angiography (ICG)
ICG angiography increases the visualization of the choroidal vasculature, which enhances the information obtained from FA using ICG. This is particularly important in the case of sub-RPE lesions and "occult" CNVs that FA could fail to reveal. ICG angiography helps distinguish hyperfluorescence due to disorganized choriocapillaris and assists with more complicated cases.
Fundus Autofluorescence (FAF)
FAF is a non-invasive imaging technique that captures the natural fluorescence of some pigments in the retina, such as lipofuscin. In the case of OHS, FAF has greater sensitivity in identifying small, nonpigmented chorioretinal scars in contrast to traditional color fundus photography. These lesions with lower levels of autofluorescence align with areas devoid of the retinal pigment epithelium, which makes them useful in assessing the stage of the disease and the risk of CNV.

Therapeutics Development for Ocular Histoplasmosis Syndrome

Bevacizumab and ranibizumab, for instance, have grown into Anti-VEGF agents and are increasingly being used for treating CNV as a consequence of OHS. These medications virtually "switch off" VEGF, which is important for the formation of esophageal blood vessels. Anti-VEGF medication given by intraocular injection has proven to greatly decrease CNV and enhance the patient's ability to see, with studies demonstrating great improvement in clear sight and less frequent therapeutics done.

Our Services

At Protheragen, we understand that each project is unique. Therefore, we offer customized services to meet the specific needs of our clients. Whether it's the development of a novel diagnostic test or the advancement of a therapeutic agent through preclinical studies, our team of experts is committed to providing the highest level of support and expertise.

Diagnostics Development

Therapeutic Development

Disease Models

Retinal Pigment Epithelium (RPE) Cell Models
Retinal Organoids
Histoplasma capsulatum Infection Models

Protheragen's preclinical research services for OHS encompass a wide range of activities, including in vitro and in vivo studies, pharmacokinetics and pharmacodynamics assessments, and toxicology testing. We utilize cutting-edge technologies and models to simulate the human disease state, allowing for the rapid and efficient evaluation of novel therapeutic agents. If you are interested in our services, please feel free to contact us.

References

Janetos, Timothy M., et al. "Multimodal imaging of an acute presentation of ocular histoplasmosis syndrome in an immunocompetent patient." American Journal of Ophthalmology Case Reports 32 (2023): 101896.
Diaz, Rocio I., et al. "Ocular histoplasmosis syndrome." Survey of ophthalmology 60.4 (2015): 279-295.