The rare, classically called "sub-hyaloid" or "preretinal" macular hemorrhage is actually located between the neuro fiber layer and the inner limiting membrane.
Causes of this hemorrhage include Valsalva maneuver, diabetic retinopathy, retinal branch vein occlusion, ruptured macro-aneurism of the retina and shaken baby syndrome. Other rare causes include thrombocytopenia secondary to bone marrow aplasia, leukemia, auto-immune hemolytic anemia, aplastic anemia secondary to drug toxicity, severe head trauma, bleeding secondary to intercourse and intraocular pressure variation during refractive surgery (LASIK). Bilateral macular hemorrhages are even more uncommon, with a few reports associated with cases of head trauma, hemolytic anemia and thrombocytopenia .
In our report, the patient presented the hemorrhage while admitted in the hospital and being constantly evaluated. Causes for Valsalva retinopathy were excluded and anemia was the most likely etiology, given that he did not present with thrombocytopenia during his time at the hospital. The explanation for retinal hemorrhages in the presence of anemia without thrombocytopenia is not clear. Factors such as anoxia, venous stasis, angiospasm, increased capillary permeability, and thrombocytopenia have been implicated in the pathogenesis of anemic retinopathy .
The hematologic investigation, including bone marrow aspirate, was compatible with drug-induced bone marrow toxicity in response to pyrimethamine or sulfur [5–8].
Both drugs interfere with the conversion of folate to its active form, tetrahydrofolate, essential for DNA synthesis. The inadequate DNA replication leads to deficient hematopoietic cell division, with megaloblastic features, and granulocytic alterations described above. Clinically, patients present with anemia which may be accompanied by leucopenia and thrombocytopenia.
Thirty days following the cessation of the medication, the patient improved, supporting our hypothesis of drug-induced medullary toxicity.