Microvascular Changes in the Retrobulbar Optic Nerve in Idiopathic Intracranial Hypertension

Purpose : To examine the microvascular changes in the retrobulbar optic nerve in idio-pathic intracranial hypertension (PTC).Methods: Both optic nerves from a 29-year-old man with a two year history of PTC were examined histologically and morphometrically. A semi-automated image analysis system and paraphenylenediamine (PPD) stain were employed to resolve sufficiently the microvascular images for counts and measurement.Results: There were 150 vessels distributed in the optic nerves which revealed the following: The average lumen of the vessels in outer sectors were larger than those of the inner sector vessels (168. 17μm2vs. 46. 99μm2; p = 0. 0338;OD; and 251. 96μm2vs. 130.02μm2;p = 0.029;OS) while in the normal control optic nerve the outer and inner area lumens were reversed in size-differential, but this did not show a statistical difference. The thickness of the PTC optic nerve vessel walls in the outer sectors was also greater than that of the walls in the inner sectors (4. 95μm vs. 2. 67μm;

Purpose : To examine the microvascular changes in the retrobulbar optic nerve in idio-pathic intracranial hypertension (PTC). Methods: Both optic nerves from a 29-year-old man with a two year history of PTC were examined histologically and morphometrically. A semi-automated image analysis system and paraphenylenediamine (PPD) stain were employed to resolve sufficiently the microvascular images for counts and measurement. Results: There were 150 vessels distributed in the optic nerves which revealed the following: The average lumen of the vessels in outer sectors were larger than those of the inner sector vessels (168. 17μm2vs. 46. 99μm2; p = 0. 0338;OD; and 251. 96μm2vs. 130.02μm2;p = 0.029;OS) while in the normal control optic nerve the outer and inner area lumens were reversed in size-differential, but this did not show a statistical difference. The thickness of the PTC optic nerve vessel walls in the outer sectors was also greater than that of the walls in the inner sectors (4. 95μm vs. 2. 67μm; p = 0.013;OD and 5. 25μm vs. 3. 34μm;p = 0. 019;OS) ; the same measurements in the normal optic nerve showed a reversed ratio, which was opposite that of the experimental group and but not statistically different. Conclusion : This pattern of microvascular changes is consistent with the selective ax-onal loss in the peripheral area of each optic nerve as much more severe than that in the inner sectors. Eye Science 1999; 15 : 7 - 12