OCR Text |
Show f" un/ a/ of Clillical Neunl- tl,'/ ri/ rallll< l/ o;..' y 9( 2): 13~ 135. / 989. Editorial Comment Optic Neuropathy in Uremia Optic neuropathy presumably due to uremia has recently been well documented by Knox and coauthors ( 1), who reported six patients. In this issue, Saini and collaborators ( 2) present another particularly interesting case of this syndrome. A 24- year- old man experienced sudden and profound bilateral visual loss ( down to finger counting in both eyes) and was found to have sluggish pupils, central scotomas, and bilaterally hyperemic optic discs. Extensive laboratory investigation was significant only for a previously undetected chronic renal insufficiency. Treatment with highdose corticosteroids produced no clinical improvement. Subsequent hemodialysis, however, was promptly followed by dramatic recovery of vision ( 20/ 40 in both eyes). This case is remarkably similar to two of the six patients reported by Knox et a1. ( 1) One, a 30year- old woman with sickle cell disease and uremia, developed marked bilateral visual loss ( no light perception right eye, and 5/ 200 left eye) and optic disc edema. Therapy with oral prednisone and hemodialysis was followed by rapid visual improvement ( 20/ 16 in both eyes). Another patient, a 16- year- old boy with immunoglobulin A ( lgA) nephropathy, presented with blurred vision ( 20/ 100 in both eyes) and was noted to have marked swelling of the optic nerve heads with extension of edema into the macula. After hemodialysis, visual acuity returned to normal. These three young patients with visual loss, disc congestion, and uremia all recovered rapidly and completely after dialysis. A third patient in Knox's series also had full visual recovery but was treated with oral steroids and was not dialyzed. This patient was also young ( 19 years old). Knox's other patients were older and had a less complete response to therapy. A 53- year- old woman developed acute renal failure due to multiple myeloma. Rapid visual loss to no light perception in both eyes ensued. Dialysis but not corticosteroid ther.' d"" ' C, · ', <, d ,-' p,. -,"\'(' r, ll months, vision im- 134 © 1989 Raven Press, Ltd., New York proved to 20/ 400 in one eye but the other eye remained amaurotic. A 60- year- old man with renal insufficiency secondary to nephrolithiasis developed " poor vision" that " slowly improved" after peritoneal dialysis, although specific acuities were not given. Several months later, his blood urea nitrogen ( BUN) level rose and he again experienced blurred vision. Visual acuity was then correctable to 20/ 60 in the right eye and 20/ 40 in the left eye, and bilateral pallid disc edema was noted. Oral steroid therapy, without renal dialysis, did not reverse the process, and vision deteriorated to no light perception in the right eye and hand movements in the left eye. The final patient in Knox's series had cryptococcal meningitis and possibly visual loss on that basis rather than due to uremia. Interestingly, none of the above discussed patients ( except the woman with cryptococcal meningitis) had been on chronic hemodialysis prior to the visual loss. We have recently seen another patient through the courtesy of Dr. Joel Glaser ( to be reported in detail later) on chronic hemodialysis who developed uremic optic neuropathy that followed a different course. This 41- year- old woman on hemodialysis for the preceding 9 years awoke with blurred vision in the right eye. Vision was 20/ 50 in the right eye with an afferent pupil on that side. The right optic disc was edematous. Over the next 2 days, vision in the eye deteriorated to only light perception. Acuity in the left eye remained 20/ 20, and the optic disc was normal. BUN was 81 mg/ dl, hematocrit was 16%, and blood pressure was 200/ 130. Extensive laboratory workup including head and orbit computed tomography and lumbar puncture was otherwise unrevealing. Prednisone 80 mg/ day was initiated and slowly tapered over 6 weeks. Vision gradually improved to 41200 in the right eye, and disc pallor ensued. Several months after the visual loss in the right eye, the patient developed blurred vision in her left eye, which worsened over the next 48 h to no light perception. The left pupil was sluggish on presen- EDITORIAL COMMENT 135 tation, and the left disc was edematous. The right eye was unchanged. Blood pressure was 170/ 110, BUN was 115 mg/ dl, and hematocrit was 20%. Magnetic resonance imaging of brain and orbits and a lumbar puncture were normal. Intravenous methylprednisolone 2 g/ day was administered for 5 days. The patient was dialyzed three times during the next 4 days. Three units of packed red blood cells were transfused, and the hypertension was better controlled. Vision slowly improved to counting fingers in the left eye. Six weeks later, visual acuity was 20/ 200 in the right eye and 20/ 800 in the left eye. Both optic discs were pale and flat. This patient differs from those previously described in that ( a) the uremic status had been relatively stable, controlled with hemodialysis, for a prolonged period prior to the onset of visual symptoms; ( b) the optic neuropathy presented unilaterally several months before involvement of the second eye; and ( c) the visual response to hemodialysis was unimpressive in this case in contrast to those with more recent onset of uremia. The pathogenesis of this syndrome is poorly understood. In addition to uremia, the patients generally have hypertension and anemia, either of which may contribute to the optic neuropathy. Whatever the mechanism, it must account for the following observations: ( a) the visual loss, although abrupt, generally develops over several days; ( b) the visual loss is reversible, at least in some instances; ( c) the optic disc is generally edematous, although the retrobulbar portion of the optic nerve may be affected; ( d) a dialysable factor is operational in at least some cases; and ( e) although generally bilateral, the process may be unilateral. We agree with Knox et al. ( 1) that ischemia is unlikely to be solely responsible for this syndrome. The mechanism may relate to focal edema of the optic nerve. It is important to recognize this syndrome, as prompt treatment with dialysis and corticosteroids may reverse the process. Patients with known renal insufficiency, if workup has been otherwise unremarkable, should be considered for such therapy. The " take home" point to the clinician, however, is that apparently healthy individuals, young or old, presenting with an acute optic neuropathy should be screened with a serum BUN and/ or creatinine level. Unless this is done, although apparently an infrequent problem, an otherwise treatable cause of visual loss- uremia- may be overlooked. Kirk E. Winward, M. D. Bascom Palmer Eye Institute Miami, Florida REFERENCE 1. Knox DL, Hanneken AM, Hollows FC Miller NR, Schick HL Jr., Gonzales WL. Uremic optic neuropathy. Arch Ophthalmol 1988; 106: 50-- 54. 2. Saini JS, Jain IS, Shar S, Mohan K. Uremic optic neuropathy. JClin Neuro- ophthalmoI1989; 9: 131- 3. J Gin Neuro- ophthalmol, Vol. 9, No. 2, 1989 |