If you have the the symptoms of histoplasmosis, your ophthalmologist will conduct a careful eye examination to confirm a histoplasmosis diagnosis.
Your ophthalmologist will be looking for two things in particular:
- The presence of histo spots, which indicate previous exposure to Histoplasma capsulatum fungus spores;
- Swelling of the retina, which signals the growth of new, abnormal blood vessels.
The examination to diagnosis histoplasmosis is similar to that used for a wet macular degeneration diagnosis. Your doctor may have you use an Amsler grid to check for histoplasmosis symptoms such as wavy, blurry or dark areas in your vision.
As part of the examination, your ophthalmologist will dilate (widen) your pupils using dilating eyedrops and examine your eyes with an ophthalmoscope, a device that allows him or her to see the retina and other areas at the back of the eye. If fluid or abnormal blood vessels (choroidal neovascular membranes) are detected, your ophthalmologist will take special photographs of your eye with optical coherence tomography (OCT) and fluorescein angiography.
OCT scanning uses light waves to create detailed images of the underlying structure of the retina. OCT images show the thickness of the retina, and can help your ophthalmologist detect swelling and abnormal blood vessels.
During fluorescein angiography, a fluorescein dye is injected into a vein in your arm. The dye travels throughout the body, including your eyes. Photographs are taken of your eye as the dye passes through the retinal blood vessels. Abnormal areas will be highlighted by the dye.