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Vascular Compression of the Optic Chiasm Resembling Glaucoma-Like Visual Field Defects*

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Vascular Compression of the Optic Chiasm Resembling Glaucoma-Like Visual Field Defects* Case Communications Vascular Compression of the Optic Chiasm Resembling Glaucoma-Like Visual Field Defects* Eedy Mezer MD1, Irene Krasnits MD1, Itzhak Beiran MD1,3, Benjamin Miller MD1, Reuven Shreiber MD2 and Dorit Goldsher MD2 Departments of 1Ophthalmology and 2Diagnostic Imaging, Rambam Medical Center, Haifa, Israel Affiliated to Technion Faculty of Medicine, Haifa, Israel Key words: normal-tension glaucoma, visual field defects, quadrantanopia IMAJ 2005;7:675-676 Open-angle glaucoma with normal in- Patient 1 prominent in the left eye [Figure B]. A traocular pressure, also known as nor- A 53 year old man had been under oph- coronal MRI through the supracellar cis- mal-tension glaucoma, is estimated to thalmic care some 4 years prior to his re- tern demonstrated low positioned ante- constitute 10–25% of all glaucoma cases. ferral to our clinic for non-specific visual rior cerebral arteries, touching the right NTG is a diagnostic challenge, as various disturbances. The patient was a chronic lateral segment of the optic chiasm, and lesions affecting the visual pathways in- smoker and suffered from arterial hyper- compressing the left one while pushing it cluding compression by normal or abnor- tension and type 2 diabetes. Ophthalmic mal intracranial blood vessels can mimic examination revealed visual acuity of 6/6 its clinical findings. In recent years, sev- without correction and applanation to- A eral studies have shown a statistically nometry of 10–14 mm Hg in each eye on significant percentage of patients with different measurements. Fundus examina- NTG who were shown to have compres- tion demonstrated bilateral shallow exca- sion of the optic nerves by normal or vation more prominent on the left side. abnormal carotid arteries compared with The diagnosis at this stage was NTG. controls or patients with high pressure Visual field follow-up during 4 years re- B glaucoma. We report two patients who vealed a non-progressive lower quadrant initially presented with clinical signs imi- binasal defect, more prominent in the tating bilateral NTG, with non-progressive left eye. Computed tomography study of binasal visual field defects due to optic the brain was described as normal. Axial C chiasm compression by low positioned and coronal magnetic resonance imag- anterior cerebral arteries. We show the ing demonstrated a bilateral downward radiologic findings and discuss possible course of both anterior cerebral arteries explanations for these observations. abutting the lateral portions of the optic chiasm (MRI images are not shown due Patient Descriptions to technically low print quality). Two cases of lateral chiasmal compres- sion were identified in the Rambam Patient 2 Medical Center Neuroophthalmology out- A 64 year old diabetic woman was diag- patient clinic. Each underwent a repeated nosed as having NTG and treated with eye exam that comprised a full neuro- timolol 0.5% twice daily and pilocarpine ophthalmologic status, including dilated 2% four times a day for 5 years. Physical fundus examination and automated vi- examination revealed visual acuity of 6/6 [A] Case 2. Fundus photos after 9 sual field perimetry testing. Each patient in each eye; maximal intraocular pressure years of follow-up showing temporal had undergone brain and visual pathways was 19 mmHg in each eye. A fundus ex- optic disk pallor in the absence of deep or wide optic disk cupping. [B] imaging by magnetic resonance imaging amination disclosed bilateral temporal Corresponding lower binasal quadran- with contrast material. disk pallor without excavation [Figure A]. tanopia on automated visual fields test- Serial visual field examinations during ing. [C] A typical coronal T1-weighted 5 years showed a stable binasal visual MRI demonstrating the right anterior field defect in the lower quadrant, more cerebral arteries (white arrows) abutting ∗ Presented at the International Neuro- the optic chiasm (asterix) and the pres- Ophthalmology Society Meeting, Toronto, sure caused by the left carotid siphon September 2000 NTG = normal-tension glaucoma on the left chiasmatic segment. • Vol 7 • October 2005 Normal-Tension Glaucoma 675 Case Communications to a lower position than the right seg- quadrantanopia and optic atrophy [1], defects, especially when the defect is non ment [Figure C]. anterior cerebral artery aneurysm causing progressive and the patient has athero- unilateral compression of the optic nerve sclerotic risk factors. Further large-scale Comment with various visual defects (unilateral epidemiologic studies are needed to esti- NTG constitutes a significant part of any hemianopia, complete anopia) [2,3], and mate the prevalence of this pathology. glaucoma clinic. Previous studies have unilateral compression of the optic chi- reported compression of the optic nerve asm causing nasal quadrantic hemiano- References by normal or diseased carotid arteries in pia [4]. Visual improvement after surgical 1. Hilton GF, Hoyt WF. An arteriosclerotic NTG. The anterior cerebral arteries pass manipulation of ectatic anterior cerebral chiasmal syndrome. Bitemporal hemiano- above the dorsal surface of the optic arteries has also been reported [5]. pia associated with fusiform dilatation of nerves as they converge to form the op- We believe that the signs and symp- the anterior cerebral arteries. JAMA 1966; 196:1018–20. tic chiasm. This close proximity between toms in our study were not only second- 2. Bakker SL, Hasan D, Bijvoet HW. Com- the anterior cerebral arteries and anterior ary to the close contact of the low po- pression of the visual pathway by ante- visual pathways may lead to compres- sitioned anterior cerebral arteries to the rior cerebral artery aneurysm. Acta Neurol sive effects of the vessels on the optic optic chiasm, but might have been, in Scand 1999;99:204–7. chiasm. This is especially true for ath- part, the outcome of other factors such 3. Versavel M, Witmer JP, Matricali B. Giant aneurysm arising from the anterior erosclerotic or ectatic vessels. This study as vascular rigidity. The first patient had cerebral artery and causing an isolated described the follow-up of two patients diabetes and arterial hypertension, and homonymous hemianopsia. Neurosurgery with a diagnosis of NTG based mainly on the second patient was diabetic; hence 1988;22:560–3. visual field studies. The absence of pro- both had up to two known risk factors 4. Ohhashi G, Kogure T, Okuda Y, et al. gression in visual field defects led us to for the development of atherosclerosis, Visual defect due to chiasmic compres- sion by the A1 portion of the anterior ce- question the diagnosis of normal-tension which results in increased arterial rigidity. rebral artery. No To Shinkei 1998;50:569–72. glaucoma. Neuroimaging proved the visu- To the best of our knowledge this is 5. Post KD, Gittinger JW Jr, Stein BM. al field defects to be the result of optic the first report in the English-language Visual improvement after surgical manip- pathway compression by low positioned medical literature on bilateral nasal visu- ulation of dolichoectatic anterior cerebral anterior cerebral arteries. al field defects caused by bilateral optic arteries. Surg Neurol 1981;15:321–4. Visual field defects resulting from chiasm compression by anterior cerebral vascular compression on neural optic arteries. Although NTG may occur in the Correspondence: Dr. E. Mezer, Dept. of pathways have previously been reported. presence of vascular compression of the Ophthalmology, Rambam Medical Center, Reports relevant to our findings include optic nerves, the etiology of vascular Haifa 31096, Israel. tortuous ectatic anterior cerebral arteries compression by anterior cerebral artery Phone: (972-4) 854-2668 forming redundant loops into the op- should be considered as a rare but valid Fax: (972-4) 854-2412 tic chiasm, causing bitemporal superior possibility in cases of binasal visual field email: [email protected] Don’t borrow or lend, but if you must do one – lend. Josh Billings (1818-85), U.S. humorist Capsule Patient-specific embryonic stem cells The generation of pluripotent patient-specific cell lines is a preclinical analyses until the remaining animal components first step toward specifically tailored cellular therapies. Hwang introduced during culture are removed and until reliable et al. isolated embryonic stem cell lines via an improved methods provide efficient, directed differentiation of stable somatic cell nuclear transfer method. These cell lines match cells of whichever cell type may be needed for therapeutic the nuclear DNA and show in vitro immunologic compatibility transplantation. with cells from the original somatic nucleus donor patients. Science 2005;308:1777 However, these patient-specific cells could only be used for Eitan Israeli 676 E. Mezer et al. • Vol 7 • October 2005.
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