MRI lesions of the optic nerves in optic neuritis

Magnetic resonance imaging (MRI) was performed in 14 patients with optic neuritis. Three patients suffered from multiple sclerosis but the etiologies of the remaining 11 cases could not be identified. They were bilateral in 6, and unilateral in 8. The MR images were compared with the symptomatic lesions of optic neuritis and pattern reversal VECP. The STIR mode (short time inversion recovery), was employed for the MRI in the orbit and T2-weighted mode in the brain. In 11 eyes with hyperemia of the optic disc, 7 eyes showed a high signal in the optic nerve with the MRI, and 9 eyes showed an abnormal pattern VECP. Seven eyes with normal disc and two eyes with a pale disc showed a high signal in the optic nerve with MRI, those 9 eyes had abnormal pattern VECP. The high signal in the optic nerve was not related to visual acuity or visual field abnormalities of patients. However, the degree of the high signal of the optic nerve lesion in MRI was associated with the clinical course and prognosis of the optic neuritis. The degree of the high signal of the optic nerve lesion decreased with the recovery of visual acuity in optic neuritis.     

Hereditary optic neuropathies: from the mitochondria to the optic nerve

PURPOSE: To review our current knowledge of inherited optic neuropathies. DESIGN: Perspective. METHODS: Literature review. RESULTS: The hereditary optic neuropathies consist of a group of disorders in which optic nerve dysfunction figures solely or prominently and direct inheritance is clinically or genetically proven. The most common of these disorders are autosomal dominant optic atrophy (Kjers' disease) and maternally-inherited Leber's hereditary optic neuropathy. Other inherited neurologic and systemic syndromic diseases will frequently manifest optic neuropathy. A selective vulnerability of the optic nerve to perturbations in mitochondrial function may underlie a final common pathway among these disorders. CONCLUSIONS: The ophthalmologist should be familiar with the clinical characteristics and diagnosis of the hereditary optic neuropathies. Recent advances in our understanding of the underlying pathophysiology of the inherited optic neuropathies may provide insight into their treatment and the treatment of acquired optic nerve disorders.     

Revascularization decompression of the optic nerve: a new surgery of the optic nerve in progressive glaucomatous optic neuropathy

A new operation on the optic nerve scleral canal, revascularization compression of the optic nerve, was carried out in 21 patients (21 eyes) in order to improve the visual functions and stabilize the glaucomatous process. The operation combines the advantages of decompression of the optic nerve by dissection of the posterior scleral ring with creation of an additional source of blood supply to the optic nerve from the myovascular bundle of the internal rectal muscle. Good functional effect and notable improvement of hemoperfusion of the optic nerve and retina were attained (period of observation up to 2 years). The degree of visual field extension correlated with the degree of increase in hemoperfusion values. Comparative analysis showed a higher functional efficiency of revascularization decompression of the optic nerve in comparison with optic nerve decompression, which is due to a more essential improvement of ocular hemoperfusion.     

Diameter of the optic nerve in idiopathic optic neuritis and in anterior ischemic optic neuropathy

Purpose: There is considerable overlap in the clinical profile of patients with idiopathic optic neuritis(ON) and anterior ischemic optic neuropathy (AION). We tested the hypothesis that the retrobulbar diameter of the optic nerve may be a criterion for the differential diagnosis between ON and AION. Methods: The diameter of the optic nerve was measured by B-scan ultrasonography with the eye in an abducted position. Only patients with a unilateral optic neuropathy were included, 16 ON patients (mean age 24years, 5 with and 11 without disc swelling) and 9patients with AION (mean age 72 years). As controls for the ON patients 10 young normal subjects (mean age25 years) and as controls for the AION patients 10elderly subjects with eye problems not related to the optic nerve (mean age 76 years) were examined. Results: In the ON patients with disc swelling the diameter of the optic nerve was 5.4 ± 0.5 mm in the affected and 3.0 ± 0.3 mm in the unaffected side. This difference was significant (Wilcoxon-test, p = 0.043). In the ON patients without disc swelling the diameter of the optic nerve was 4.4 ± 0.4 mm in the affected and 3.0 ± 0.3 mm in the unaffected side. This difference was significant (Wilcoxon-test, p = 0.003). In the AION patients the diameter of the optic nerve was 3.0 ± 0.3 mm on the affected and2.8 ± 0.4 mm on the unaffected side. This difference was not significant (Wilcoxon-test, p =0.093). Comparing the optic nerves with ON and AION to those of the controls, the diameter was significantly enlarged in the nerves with ON and normal in the nerves with AION (one factor repeated ANOVA). Conclusion: The diameter of the optic nerve is increased in ON without disc swelling and even more so in ON with disc swelling. The enlargement is probably due to edema of the nerve itself, not the surrounding subarachnoidal space. In AION, the diameter of the optic nerve is normal. Measuring the diameter of the optic nerve by B-scan ultrasonography is particularly useful in the differential diagnosis between ON with disc swelling and AION. This revised version was published online in August 2006 with corrections to the Cover Date.     

Decompression of the optic nerve in the optic canal. A transorbital approach

Blindness can result from pressure on the optic nerve in the optic canal, either from trauma or from neoplasm. The usefulness, timing, and technique of surgical decompression of the optic canal remains controversial. The present paper describes eight patients with optic nerve compression, who had the optic nerve decompressed through a transorbital approach. Because this technique is technically simple and is associated with a low morbidity, it offers a treatment alternative to this difficult group of patients.     

Colobomas of the optic area

A 24-year old woman displayed a coloboma of the right optic nerve with multiple small parapapillary retinochoroidal colobomas. This rare association makes one suspect that the pathogenesis of colobomatous defects of the optic disc area are caused by a faulty closure of the embryonic fissure and an abnormal maturation of the cells of the anlage of the optic nerve head.     

Leukemic involvement of the optic nerve

We studied five cases of leukemia with invasion of the optic disk and optic nerve. Two patients had acute lymphoblastic leukemia and three had acute myelogenous leukemia. All patients received intrathecal injections of chemotherapeutic drugs including methotrexate, cytarabine, and prednisolone. Three patients underwent irradiation therapy of the whole brain and optic nerve. While initial improvement in the ophthalmic abnormalities, such as optic disk edema, flame-shaped retinal hemorrhages, and dilation of the retinal vein, was noted, optic atrophy was later found in all eyes.     

Pseudoduplication of the optic nerve head.

BACKGROUND: Pseudo-doubling of the optic nerve head is a spectacular clinical entity, in which a lesion resembling an optic disk appears adjacent to the true optic disk. CASE REPORT: A case of unilateral pseudo-doubling of the optic disk with bilateral optic nerve pits is presented. CONCLUSIONS: The lesion is congenital, and represents a chorioretinal coloboma with optic disk involvement. Pseudo-doubling can be differentiated from true doubling of the optic nerve by the imaging techniques of ultrasonography, computerized tomography, and magnetic resonance imaging.     

Human optic nerve fiber count and optic disc size.

In the optic nerve head, the optic nerve fibers are represented by the neuroretinal rim. The rim area showing a high interindividual variability is positively correlated with the optic disc size. This study was performed to address the question of whether, in addition to having a larger neuroretinal rim, eyes with large optic discs also have a higher count of optic nerve fibers compared to eyes with small optic nerve heads. Histologic semithin sections of 72 optic nerves of 56 cornea donors were histomorphometrically evaluated using a computerized image analyzer. The optic nerve fiber count increased significantly (P = 0.01) with enlarging optic disc size. The nerve fiber count was positively correlated with the retrobulbar optic nerve cross section area. It decreased with advancing age, with a mean annual loss of about 4,000 fibers. The nerve fiber density per disc area decreased with increasing optic disc area. Mean and median of the minimal nerve fiber diameter was larger in older subjects. The results may indicate that the optic nerve fiber count, and the anatomic reserve capacity in progressive optic neuropathies, are higher in eyes with large optic discs than in eyes with small optic nerve heads. The optic nerve fiber population decreased with advancing age. This is important for progression, pseudoprogression, and prognosis of optic neuropathies. Optic nerve fiber crowding is more marked in eyes with small optic discs than in eyes with large optic nerve heads. The age-related loss of predominantly small optic nerve fibers can potentiate the optic nerve atrophy in glaucoma and Alzheimer's disease, with both damaging preferentially large axons.     

Indirect injury to the optic nerves and optic chiasm

Abstract. Twenty-five cases of indirect injury to the optic nerve or chiasm following blunt trauma to the head were retrospectively reviewed. Falls onto the head and road traffic accidents together accounted for most (88%) of the head injuries. Bony skull fractures were identified in 23 cases (92%), although in only five of these (20%) was one of the optic canals or anterior clinoid processes involved in a fracture. Visual loss was bilateral in 11 patients (44%). In eight of these bilateral cases the visual field defects suggested a lesion at or near the optic chiasm. In one case optic nerve function deteriorated after the initial assessment. This deterioration was reversed by treatment, which consisted of surgical drainage of an orbital haematoma and systemic corticosteroids.     

Hypoplastic optic nerves studied with B-scan ultrasonography and axial tomography of the optic canals.

Radiologic studies of the optic foramina in cases of optic nerve hypoplasia have been inconsistent, some authors reporting normal foramina, others finding small foramina. The technique of axial tomography of the optic canals has been found more useful in this regard than plain foramen views, and has demonstrated small canals in cases of optic nerve hypoplasia. A case of bilateral hypoplasia is presented in which the discs were one half normal size, the optic nerves measured 2 mm in diameter on B-scan ultrasonography, and the optic canals were about 4 mm in diameter radiographically on the axial tomograms. These measurements are compared with normals of 4 to 4.5 mm for scans of the optic nerve, and a reported average optic canal width of 5.5 mm. A second case of less severe hypoplasia also presented a small ultrasonic nerve pattern of 3.5 mm. With the techniques of ultrasonography and axial tomography, the course of hypoplasic nerves can be followed from the level of the retina to the optic chiasm posteriorly. It is suggested that the optic canal dimensions correspond closely to the size of the optic nerve in cases of hypoplasia. When the nerve is only slightly hypoplastic the radiographic change in foramen or canal dimensions may not be detectable. Reasonably accurate measurements of the nerve may be more easily obtained with ultrasound.     

Pseudodrusen of the optic disc. Papilledema simulating buried drusen of the optic nerve head

The distinction between true papilledema and pseudopapilledema rests on characteristics of the optic disc when examined ophthalmoscopically. Buried disc drusen frequently simulate papilledema and often result in misdirected diagnostic maneuvers in search of a cause for presumed intracranial hypertension. When an elevated optic disc exhibits an irregular, "lumpy, bumpy" border, a diagnosis of buried drusen of the optic nerve is usually made. We report a case with papilledema secondary to increased intracranial pressure in which the margins of the swollen optic disc presented this lumpy, bumpy border characteristic of buried drusen. The lumpy character of the disc border disappeared with resolution of the papilledema, and ultrasonography demonstrated the absence of any buried drusen. Other characteristics of papilledema, including extension of the disc swelling into the peripapillary nerve fiber layer, telangiectasia of the superficial vessels of the optic disc, and obscuration of the retinal vessels as they crossed the margins of the optic disc, provided strong evidence of true papilledema and remain the most reliable findings allowing a distinction between true papilledema and pseudopapilledema.     

Management of optic neuritis

To improve understanding and effectiveness of therapy in optic nerve disease, various causes of so-called optic neuritis should be identified when possible. The clinical characteristics of demyelinating optic neuropathy can be contrasted with those of ischemic optic neuropathy, nutritional optic neuropathy, true optic nerve inflammation (e.g., luetic), optic nerve infiltration with tumor, and compression neuropathy caused by adjacent tumor. Radiologic studies and other means of investigating patients with optic neuritis are reviewed. Arguments in favor of, and against, treatment of presumed demyelinating optic neuritis are presented along with representative corticosteroid treatment regimens. The natural tendency toward spontaneous improvement of optic neuritis makes the effect of treatment difficult to assess.     

Enlargement of the optic disk in childhood optic nerve tumors

Two children, a 9-year-old girl and an 8-month-old girl, were first examined because of unilateral proptosis. Both children were found to have unilateral optic nerve glioma, accompanied in the second case by neurofibromatosis. Two years after Patient 1 was first examined, the initial findings of thin vertical retinal striae and a gray opacification of the peripapillary retina had resolved. The enlarged left optic disk had an average diameter of 2 mm while that of the normal right optic disk was 1.6 mm. The disk-arteriolar ratio was R.E.:16:1 and L.E.: 20:1. Four years later, the patient's visual acuity was still 20/20 in both eyes and the only visual field abnormality was an enlarged blind spot corresponding to the enlarged left optic nerve head. Fundus photographs, orbital echography, and computed tomography showed no change in the size or location of the optic nerve glioma during the six-year follow-up period. In Case 2, the initial intraocular pressure was higher in the proptotic right eye than in the left eye (25 vs 19 mm Hg), but subsequent intraocular pressures were within normal limits and approximately equal in the two eyes. The disk-arteriolar ratio was R.E.:21:1 and L.E.: 18:1 and the cup-disk ratio was R.E.: 0.7 and L.E.: 0.3. Computed tomography disclosed an enlarged right retrobulbar optic nerve, a superior orbital fissure that was much larger on the right than on the left, and a larger cavernous sinus on the right. The right sphenoid bone was partially absent. Despite mild developmental delay, the patient's visual acuity apparently remained normal and the ophthalmologic findings did not change significantly during the 18-month follow-up period.     

Posterior ischemic optic neuropathy. I. Blood supply of the optic nerve

The blood supply of the posterior optic nerve was investigated in 10 monkeys after an injection of synthetic resin into the carotid arteries. The posterior intraorbital and intracanalicular optic nerves were supplied by a centripetal vascular system, formed by the pial vessels arising from the first branches of the ophthalmic artery. Superior and inferior vascular semicircles were detected in the intracanalicular optic nerve. The intracranial optic nerve was supplied by branches of the internal carotid artery, anterior cerebral artery and/or anterior communicating artery, and ophthalmic artery.     

Ultrasonography of the optic nerve

The orbital optic nerve is extremely difficult to study clinically, as is the optic disc in eyes with opaque media. The combined use of quantitative A-scan and B-scan ultrasonography allows us to evaluate the intraocular and orbital optic nerve with a degree of precision and elegance not previously attainable. Disc cupping, elevation, drusen and many peripapillary affections may be demonstrated by ultrasonographic techniques. In the orbit. the optic nerve and its cerebrospinal fluid cuff may be studied and measured, and both intrinsic and extrinsic perineural mass lesions may be demonstrated. These techniques also allow for the differentiation of intrinsic neural masses from perineural tumors. In nearly all cases of orbital mass lesions involving or surrounding the optic nerve, a tissue diagnosis may be made with a high degree of reliability by ultrasonographic investigation. Ultrasonography is non-invasive, repeatable ‘ad lib’, and free of radiation or other iatrogenic sequelae.     

Pathogenetic mechanisms of optic nerve lesions in acute vascular optic neuropathies

The authors analyze the findings of histomorphologic and immunomorphologic studies of 20 cadaver optic nerves from subjects with a history of acute vascular optic neuropathies due to atherosclerosis, eventuating in optic nerve atrophy: 13 atrophic optic nerves and 7 pair nerves from clinically normal eyes of the same patients were examined. The blood sera of 30 patients suffering from acute vascular optic neuropathies were tested. Noteworthy that vascular optic neuropathy associated with atherosclerosis is a bilateral process. Vascular insufficiency due to sclerotic changes in vessels of various diameters undoubtedly contributes to the pathogenesis of the optic nerve impairments in the involved and clinically healthy eyes. The developing immune status disorders and autoimmune processes also contribute to the genesis of sclerotic shifts in the vessels and optic nerve atrophy in both eyes.     

Anterior optic nerve blood flow in experimental optic atrophy

This study attempts to establish whether neurogenic optic atrophy induces changes in anterior optic nerve circulation and to determine how noninvasive techniques of measuring blood flow in vivo compare to microsphere distribution. Five cats underwent unilateral optic nerve transection in the orbital apex and a sham procedure in the contralateral eye. Two to three months later, no abnormalities were detected by fluorescein angiography. Laser Doppler measurements demonstrated a 53% decrease in red blood cell speed through the capillaries of the atrophic optic nerve heads in vivo. Optic disk reflectance measurements of anterior optic nerve blood volume in vivo demonstrated a 51% decrease in the estimated blood volume of the capillaries in atrophic optic nerve heads. Flow was calculated on the basis of these noninvasive measurements and demonstrated an average decrease of 74% in optic atrophy. Histologic studies of microsphere distribution demonstrated an average decrease of 80% in flow to the anterior optic nerve in optic atrophy. These results suggest that anterior optic nerve blood flow is significantly reduced in primary neurogenic optic atrophy. This study also demonstrates that the noninvasive measurements of blood flow are substantiated by histologic evaluation of microsphere distribution.     

Pits of the optic papilla in large optic nerve papillae. Papillometric characteristics in 15 eyes

Fifteen optic nerve heads with pits measured by optic disk planimetry according to Littmann and Jaeger's method were significantly larger than previously determined normal optic nerve heads. Their area measured 4.84 +/- 1.42 mm2 (2.77-8.02 mm2), their horizontal diameter 2.42 +/- 0.42 mm (1.76-3.38 mm) and their vertical diameter 2.53 +/- 0.30 mm (1.14-3.06 mm). The quotients of minimum to maximum diameter and the angle between the maximum diameter and the horizontal line were similar to those in normal optic disks. Because of their enlarged area but normal form this pathologic entity forms a subunit of macrodisks. The pits were located in 14 optic disks on the temporal side on average 100 degrees from the upper disk pole, and in two optic disks on the nasal side about 85 degrees from the upper pole. In two cases they were double and in one bilateral. Their area and number were significantly correlated (p less than 0.001 and p less than 0.05) to the area of the optic disk. With increasing optic nerve head size the optic cup was less excavated. The largest optic disk seen in this study did not have one at all. There might be a stepless continuation from normal-sized optic disks to macrodisks with physiologic macrocups and to optic nerve heads with pits. These represent a maximum extreme in the spectrum of optic disk anomalies and diseases associated with optic nerve head size.     

Hereditary optic neuropathies

AIMS: To provide a clinical update on the hereditary optic neuropathies. METHODS: Review of the literature. RESULTS: The hereditary optic neuropathies comprise a group of disorders in which the cause of optic nerve dysfunction appears to be hereditable, based on familial expression or genetic analysis. In some hereditary optic neuropathies, optic nerve dysfunction is typically the only manifestation of the disease. In others, various neurologic and systemic abnormalities are regularly observed. CONCLUSION: The most common hereditary optic neuropathies are autosomal dominant optic atrophy (Kjer's disease) and maternally inherited Leber's hereditary optic neuropathy. We review the clinical phenotypes of these and other inherited disorders with optic nerve involvement.