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Ocular Histoplasmosis or, what did I do to derve this? Ocular Histoplasmosis starts as Systemic Histoplasmosis. Systemic Histoplasmosis is caused when, after inhaling the histoplasmosis spores, the spores under certain temperature conditions, turn into yeasts. The spore, which is called Histoplasmosa Capsulatum, isfrom a fungus which can grow in soil and its grouwth is aided by bird (water fouwl, chickens, swallows, etc) and bat droppings. Click here for a detailed description of the fungus Histoplasmosis Capsulatum. Histo contamination occurs heaviest in areas near bodies of water and caves but, since the spores become airborne, the risk cannot be contained to any specific place. The spores may travel miles on winds and affect people far away from where they originate. The histoplasmosis organism causes an influenza like illness which lasts for up to two weeks. The patient may experience fever and weakness. The histo bug affects the lungs and the eyes mainly. It leaves scarring that may be detected in an eye examination. These scars, which in the case of Ocular histo are what cause the sight degeneration, usually later in life. Ocular Histoplasmosis occurs when abnormal blood vessels grow through the healed histo scars and into the interior of the eye. This condition, which is secondary to Ocular Histoplasmosis is called Sub Choroidal Neo-Vascularization. This may cause bleeding or increased scarring. If the scars are located close to the macula or center of vision, which is usually the case, reduction or loss of central vision may occur. Treatment of Ocular Histoplasmosis Ocular Histoplasmosis is treated according to varying aspects of the diseases stage of advancement, amount of scarring, proximity to the central vision and doctor preference. Unfortunately, there is no ONE treatment that seems to be 100% effective, but some treatments are more effective than others in certain cases. Below are summaries of some of the better treatments available. Laser Surgery Laser surger is done in a doctors office or hospital facility. The patient is injected with flourisine dye and then a succession of rapid pictures are taken by a high speed camera of the interior of the eye. The patient is then taken to the laser and seeted with there head resting on a chin pad. The doctor wil use a sighting lens which is applied to the eye using lubricant. The doctor will then use the pictures to determine where laser treatment will be effective and commence to "cauterize" the invading blood vessels. The treatment is usually painless, and recovery time is very short at one or two days The treatment is effective when the neo-vascularizations are away from the macula. Due to the destructive nature of the laser, treatment near the macual can be very damaging as the treatment will kill optic cells in the process. Sub Macular Surgery Provided by Rae Sub macular (sub mac for short) is a procedure where veins are removed from the central vision of the eye due to ocular histoplasmosis. The procedure, on average, takes approximately 1 ½ hours to perform, but may vary either way. During surgery, a clamp is used to keep the eye open. The fluid from the eyeball is drained allowing the eyeball to collapse. This enables the surgeon access the retina, at the back of the eye. Once collapsed, the surgeon then makes an incision to expose the central vision where the veins are growing. In this area, there is a piece of vitreous jelly that has to be removed before getting to the veins. Once removed, the veins are extracted and stitches are put in where there are incisions. The surgeon will fill the eyeball back up, using 25 to 50% saline, with the rest being gas. The gas is used to keep the retina in place and prevent bleeding after surgery. The paitient must keep their head down for this to work properly The surgeon will usually recommend that you be awake for the procedure (a sedative is given) due to the fact that anesthetic may cause nausea and vomiting in some people. If this happens, it can create pressure and strain on they eye, which is to be avoided at all costs after surgery (one actually doesn't realize how much strain we put on the eye). After surgery, the surgeon will ask you to keep your head down (so that the gas bubble in your eye pushes on the retina). This period has varied from doctor to doctor. They may say that you can walk with your head up but sleep face down for the next 2-6 nights and then sleep on the opposite side or they may ask you to stay face down 24 hours a day until the gas bubble is totally gone (some have reported this period of time to be longer). Your recovery period may be 1 week but could take up to 6 weeks or longer, depending upon the person. You will be told to avoid any kind of pressure or strain to the eye, avoid getting soap, water, etc. in the eye and to avoid all extracurricular activities until further recommendation. You will see redness to the eye where the stitches are and may be given drops to decrease the redness, dilate the eye and prevent infection. You will also have swelling and bruising from the clamp (which usually goes away within the week). With Sub Mac surgery, the ultimate goal is to remove the veins to stop the growth and restore vision. With surgery, it may so happen that full vision will not result (as in central vision). Vision may improve or vision may stay the same. The results will usually depend on the veins forming a scar, a scar after surgery and the person themself. Photodynamic Therapy (PDT) Provided by Karen Gray Photodynamic Therapy (PDT) or Visudyne therapy is a promising new treatment for histoplasmosis patients that involves sealing off leaky blood vessels without damaging the retina itself, thereby preserving vision. This means that PDT may have benefits for patients whose most central vision, the vision needed for reading, driving and other functional activities, is affected and whom the current thermal laser therapy is inappropriate. A light activated dye called verteporfin binds to leaky blood vessels in the eye and makes the blood vessels very sensitive to low-intensity (689 nm) red laser light. PDT is a relatively simple two-step procedure that can be performed in a doctor's office. Initially, Verteporfin dye is injected into the patients arm over a period of ten minutes. Fifteen to twenty minutes later, the doctor directs a non-thermal laser light beam into the eye to activate the drug, using careful measurements from previous photographs of the eye (fluorescein angiograms). The laser treatment is painless and brief. After the treatment, patients are instructed to wear protective sunglasses and to avoid direct sunlight for a period of up to one week. Follow-up examinations including fluorescein angiography is required to assess whether the treatment was effective. PDT frequently needs to be repeated. The advantages of PTD include few known side effects and successful control of leaky blood vessels in some cases. It also does not damage the overlying retina. Disadvantages include the fact that the new treatment usually closes abnormal blood vessels temporarily, not permanently, resulting in the frequent need for more than one treatment session. Also, PDT seems to work best for eyes with early detection of leakage and relatively active patches of abnormal blood vessels beneath the retina. Substantial blood under the retina makes PDT less likely to be effective. Verteporfin dye is expensive and Medicare has not, as yet, addressed payment for the dye. The U.S. Food and Drug Administration only recently (April 12, 2000) approved PDT or Visudyne therapy for the treatment of Age Related Macular Degeneration (a disease with similar symptom to Histoplasmosis). However, there are doctors in the US that will likely treat histoplasmosis patients in an "off label" manner based on the preliminary findings of clinical trials. The two companies backing the treatment - QLT PhotoTherapeutics Inc. in Vancouver and CIBA Vision in Atlanta, have applied for clearance of the therapy with Health Canada. A review is expected to take place in late 2000. You can seek additional information by viewing the Visudyne web site or by calling 1-800-821-2450 within North America. Other Treatments This spot is reserved for other forms of treatment for Ocular Histoplasmosis. It has been found by some individuals that Green Tea can help to slow grow of the offending membrane ans some report sharpened vision. Green Tea can be bought at any grocery store and it has been said that it is available in tablet for (strange) from health food stores. Blueboerries have been said to aid in sharpening the vison as well. Whether this is true is up to the individual, but blueberries are tasty so why not?! |