Nerve Sheath Decompression for Nonarteritic Ischemic Optic Neuropathy Improves Multiple Visual Function Measurements
Optic
Shalom E. Kelman, MD, Michael J. Elman, MD
Optic nerve sheath decompression performed in seven patients with nonarteritic anterior ischemic optic neuropathy. Visual function was evaluated by measurement of visual acuity with \s=b\
was
Early Treatment Diabetic Retinopathy Study charts, color vision testing, quantitation of relative afferent pupillary defects with neutral-density filters, and Goldmann and Humphrey perimetry. Visual acuity improved markedly in all patients (at least doubling of the visual angle); the peripheral visual field expanded by at least 20\s=deg\(as measured by Goldmann perimetry) in six patients. Three patients also experienced marked improvement in color vision, relative afferent pupillary defect, and foveal sensitivity. Our experience supports the possible beneficial effect of optic nerve sheath decompression in patients with nonarteritic anterior ischemic optic neuropathy. (Arch Ophthalmol. 1991;109:667-671) standardized
weeks after onset of symptoms."3 The dynamic, evolving visual loss seen in progressive NAION may relate to pro¬ gressive ischemia and blocked axoplasmic transport.4,5 See also pp 612 and 613.
Sergott et al4 have reported that 12 of 14 patients with progressive NAION showed marked improvement in visual function following optic nerve sheath decompression (ONSD) with ly¬ sis of subarachnoid adhesions. Encour¬ aged by these results, we performed ONSD in five consecutive patients with progressive NAION and two pa¬ tients with nonprogressive NAION. Comprehensive visual function studies were performed in all patients in a standardized fashion. PATIENTS AND METHODS
study comprised four men and three whose ages ranged from 55 to 85 years (mean, 69 years) (Table). All patients presented with painless decreased central visual acuity and visual field defects typical The
"M" onarteritic ischemie
optic neuropathy (NAION) typically presents with sudden, often profound visual loss from anterior optic nerve infarction.1 In up to 25% of affected patients, visual acuity continues to worsen 1 to 4 Accepted for publication December 4, 1990. From the Neuro-Ophthalmology Service (Dr Kelman) and the Clinical Trials and Epidemiology Unit (Dr Elman), Department of Ophthalmology, University of Maryland School of Medicine, Baltimore.
Reprint requests to the Neuro-Ophthalmology Service, Department of Ophthalmology, University of Maryland Hospital, 22 S Greene St, Baltimore, MD 21201 (Dr Kelman).
women
of NAION.1' Disc edema and peripapillary hemorrhages were present in the involved eye. Slit-lamp examination revealed no evi¬ dence of inflammatory cells in the anterior segment or vitreous. Vasculitis screening, including determination of a Westergren erythrocyte sedimentation rate, yielded normal findings. None of the patients had a prior history of visual loss consistent with optic neuritis or a history of neurologic disease consistent with multiple sclerosis. Five patients developed progressive worsening of visual acuity and visual field
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loss 1 to 3 weeks after the onset of symp¬ toms. In contrast, two patients experienced immediate, profound visual loss to their preoperative level without progressive loss of visual function. Bilateral congenital anomalous discs' (lack of physiologic central cup) were noted in six patients. Patient 2 had experienced NAION in the fellow eye 2 years before the current episode. Follow-up ranged from 3 to 10 months (mean, 7 months). The remaining clinical features are summarized in the Table. The best corrected visual acuity was mea¬ sured with the Early Treatment Diabetic Retinopathy Study (ETDRS) charts with standardized lighting." When worse than 5/200, visual acuity was graded as counting fingers, hand motions, or light perception. Color vision was assessed by Hardy-RandRittler color plates. Relative afferent pupil¬ lary defects (RAPDs) were quantified with neutral-density filters ranging in strength from 0.3 to 3.0 log units.9 A certified techni¬ cian measured ETDRS visual acuity, per¬ formed Goldmann peripheral visual field testing, and monitored Humphrey program 24-2 automated perimetry. Visual acuity was considered improved when (1) the visual angle doubled (ie, im¬ proved by three or more lines, eg, from 20/100 to" 20/50) or (2) it increased by at least one level of central visual function when visual acuity was less than 5/200 (eg, from hand motions to counting fingers at 1 ft). Assessment of visual field improvement was based on an expansion of at least 20° of the V-4-e isopter on Goldmann perimetry or an increase of 5 dB of mean deviation (MD) on automated fields. RESULTS
Surgical Findings All patients underwent modified ONSD with lysis of subarachnoid adhe-
Clinical Features of Patients With Nonarteritic
Eye That Was Acutely No./Age,
Involved and Underwent
y Sex
Surgery
/75/F
OD
Patient
Interval From
Ophthalmologic Medical
History
Stable angina
History Congenital anomalous discs OU; cataract extraction OD 4 wk before visual loss NAION OS 2 y prior; congenital anomalous discs OU
2/66/M
OD
Hypertension
3/75/M
OD
Non-insulin dependent diabetes for 5 y;
4/63/F
OS
receiving oral agents for 4y Hypertension
5/85/F
OD
Labile
hypertension
Congenital
Onset to
Surgery,
Preoperative VA, OD, OS
d
Postoperative VA, OD, OS
15
CF, 20/20
20/100, 20/20
40
CF, 20/800
20/200, 20/400
CF, 20/25
5/160, 20/25
20/25, CF
20/25, 20/125
CF, 20/40
20/200, 20/40
20/400, 20/20
20/80, 20/20
anomalous
discs OU
None
Congenital anomalous
16
discs OU 6/55/M
OD
Congenital anomalous
None
discs OU
Cataract OS; congenital HM, 20/80 Right-sided pontine infarct anomalous discs OU 3 y previously; hypertension for 10 y VA indicates visual acuity; RAPD, relevant afferent pupillary defect; CF, counting fingers at 1 ft; F, foveal sensitivity (in decibels); MD, tions; and PCA, posterior ciliary artery. fPlus sign indicates progressive disease; minus sign, nonprogressive disease. OD
sions by the same surgeon (S.E.K.) according to the method described by Sergott et al.1" Surgery was performed between 14 and 40 days after the onset
of visual symptoms. No correlation found between the timing of sur¬ gery and visual outcome. At surgery, mild distention of the optic nerve sheaths was noted, al¬ though not to the extent we have observed in pseudotumor cerebri. In patient 7, a medial posterior ciliary artery was markedly sclerotic and ap¬ peared to be occluded; in the remaining cases, the vessels overlying the optic nerve sheath appeared to be normal. Incision of the meningeal sheath re¬ sulted in the release of moderate amounts of cerebrospinal fluid (CSF), sometimes interspersed with small lip¬ id droplets.4 In three patients, the consistency of the arachnoid appeared to be thickened and gumlike (Table). An arachnoid biopsy was attempted without success. There were no surgi¬ cal complications. was
Visual
All
Recovery
patients showed marked
im¬
provement in visual acuity followingsurgery (Table, Fig 1). Patients 1 and
experienced improved vision within the first week after surgery. In the remaining five patients, visual recov¬ ery usually began by the third postop¬ erative week, and vision continued to improve during the next 8 weeks. The results of preoperative and postoperative color vision testing,
2
20/160, 20/70
mean
deviation; HM, hand
mo¬
RAPD measurements, and visual field
testing are recorded in the Table. The peripheral Goldmann visual fields im¬ proved in six patients. The three pa¬
tients in whom color vision test¬ ing showed improvement also demon¬ strated improvement of the RAPD and foveal sensitivity as well as expansion of Goldmann visual fields. In the remaining four patients, automated fields were deemed unreliable because of excessive fixation losses or high false-positive and false-negative re¬ sponses. These four patients also failed to show improvement in RAPD and color vision, even though visual acuity improved. However, the Goldmann vi¬ sual field expanded markedly in three of these four patients. The clinical courses of three repre¬ sentative cases are presented in detail below. Patient 1
75-year-old hypertensive white noted sudden visual blurring in her right eye. Four weeks earlier, she had undergone an uncomplicated ex¬ tracapsular cataract extraction with a posterior chamber intraocular lens im¬ plant. Two weeks postoperatively, vi¬ sual acuity was 20/25 OD; 2 weeks later, the patient noticed increased blurring of vision, which progressively worsened during the next week. She was examined 9 days after the onset of
Fig 1 Preoperative and postoperative visu¬ al acuities in seven patients treated with optic nerve sheath decompression for nonarteritic anterior ischemie optic neuropathy. The 45° solid line represents no change in visual acu¬ ity. HM indicates hand motions; CF, counting —
.
fingers.
A
woman
her initial symptom of blurred vision. Visual acuity measured 20/400 OD and 20/20 OS. An RAPD and an inferior
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altitudinal visual field defect were not¬ ed. The optic disc was swollen with streak peripapillary hemorrhages. The patient was referred to the University of Maryland (Baltimore) Neuro-Ophthalmology Service for con¬ sideration of ONSD. In just 2 days, distance visual acuity in the right eye declined to counting fingers at 1 ft. She could not identify any Hardy-RandRittler pseudoisochromatic color plates with the right eye. An RAPD, measur¬ ing 0.9 log units, was present in the right eye. The markedly elevated right
Anterior Ischemie
Optic Neuropathy (NAION)* Humphrey Color
Progressivet
Preoperatively
Visual Field
Postoperatively
Color
(Change)
Preoperatively
Postoperatively
0.9
0.3
3/10
RAPD
(Change)
Goldmann Visual Field + 25°
Preoperalively F=0 MD -20.8 =
Postop¬ eratively
Operative Findings
10
=
/
0.3
0.3
+30°
Not reliable
Thick arachnoid
0/10
0/10
2.1
2.1
No change
Not reliable
Thick arachnoid
F MD
=
0
=
-17.11
/ +0.9
0/10
0/10
+ 30°
1.2
1.2
+ 50°
F MD
=
( 25.3 -
10
F=13 MD -15.25 =
Not reliable
1/10
mo
F=27 MD -9.52
/
+0.9
Follow-up,
Thick arachnoid
F
=
22
MD
=
-18.3
Not reliable
10
10
PCA occlusion
optic disc was surrounded by peripapil¬ lary hemorrhages. The left optic disc was small and cupless. Goldmann visu¬
al fields demonstrated a relative inferi¬ or altitudinal scotoma involving central fixation. Humphrey program 24-2 pe¬ rimetry revealed a foveal sensitivity of 0 dB and global depression with an MD of -20.8 dB (Fig 2, left). An uncomplicated right-sided ONSD with lysis of subarachnoid adhesions was performed. By the third postoper¬ ative day, the patient noted some sub¬ jective visual improvement; she now could identify faces, which she was unable to recognize preoperatively. One week postoperatively, visual acu¬ ity improved to 20/100. Five of 10 color plates were correctly identified. Her RAPD improved to 0.3 log units. Auto¬ mated perimetry showed improvement on both MD and foveal sensitivity (Fig 2, right). Goldmann visual fields ex¬ panded by 25° to the V-4-e isopter. Ten months postoperatively, visual acuity remains stable at 20/100. Optic disc pallor developed superiorly, and disc edema completely resolved. Patient 2
A
man was referred be¬ of acute onset of blurred vision in his right eye. Seven years earlier, he experienced a sudden loss of vision in his left eye following cataract ex¬ traction, attributed to ischemie optic neuropathy. The patient was first seen 7 days after the onset of his symptoms; visual acuity was 20/100 OD. He was
66-year-old
cause
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Fig 2. Left, Preoperative pattern deviation depiction of the Humphrey 24-2 visual field in patient 1. Mean deviation was 20.8 dB, and foveal sensitivity was zero. Right, Postoperative pattern deviation depiction of the Humphrey 24-2 visual field in patient 1. Mean deviation was 9.52 dB. and foveal sensitivity was 27 dB. Note increased sensitivity, especially supranasally. —
-
-
treated with oral prednisone, starting at 60 mg/d and tapering over 2 weeks to 5 mg/d. During this time, despite treatment, the patient noted progres¬ sive worsening of his vision. He was referred to the University of Maryland Hospital 3 weeks after the onset of his symptoms. Visual acuity measured counting fingers in the right eye at 1 ft and 20/800 OS. On color plate testing, the patient identified zero of 10 plates with both eyes. An afferent pupillary defect measuring 0.3 log units was present in the right eye. Goldmann visual fields showed marked constric¬ tion of the V-4-e isopter in both eyes. A fundus examination revealed supe¬ rior disc swelling, with a flame-shaped hemorrhage in the right eye. The markedly pale optic disc in the fellow eye also lacked a central cup. We performed an uncomplicated right-sided ONSD with lysis of subarachnoid adhesions. One day after sur¬ gery, the patient noted improvement in brightness and color vision. Visual acuity improved to 20/200 at postoper¬ ative week 1. Five months postopera¬ tively, the patient's visual acuity is maintained at 20/200 OD; visual acuity in the eye not operated on has im¬ proved to 20/400. The optic disc edema has evolved into disc pallor, and visual fields have expanded in both eyes. Patient 6
A 55-year-old computer programmer noted the acute, painless onset of a central blur in his right eye. When the patient was initially seen 15 days after the onset of symptoms, visual acuity was 20/400 OD and 20/20 OS. On color plate testing, one of 10 plates was identified with the right eye and 10 of 10 plates with the left eye. A 1.5-log unit RAPD was measured in the right eye. Fundus examination revealed a swollen superior optic disc with a cot¬ ton-wool spot off the disc at the 5-o'clock position. The optic disc in the fellow eye had a congenital anomaly without a central cup. Goldmann visual fields in the right eye demonstrated marked depression of the entire field, especially inferiorly. Foveal sensitivity was 6 dB (Fig 3, left). The patient did not experience any subjective worsen¬ ing from the onset of symptoms. One month following ONSD sur¬ gery, visual acuity had improved to 20/80 OD. Color plate testing results improved to seven of 10 plates identi¬ fied with the right eye. The RAPD had decreased to 0.6 log units. Five months following surgery, the patient has maintained a visual acuity of 20/80 OD, and eight of 10 color plates were iden¬ tified correctly; a 0.6-log unit RAPD
Fig 3.—Left, Preoperative pattern deviation depiction of the Humphrey 24-2 visual field in patient 6. Mean deviation was -24.3 dB, and foveal sensitivity 6 dB. Right, Postoperative pattern deviation depiction of the Humphrey 24-2 visual field in patient 6. Mean deviation was 18.3 dB, and foveal sensitivity was 22 dB. Note the marked increase in sensitivity in the superior field. -
remains in the right eye. Optic disc edema resolved into diffuse pallor. Fo¬ veal sensitivity has increased to 22 dB. Mean deviation has improved from -24.3 dB to -18.3 dB, with marked improvement in the sensitivity of the superior visual field (Fig 3, right). COMMENT
Optic nerve sheath decompression, with release of perineural CSF, mark¬ edly improved visual acuity in all seven of our patients with NAION. Five of the patients experienced progressive visual loss before surgery. Even the two patients with nonprogressive dis¬ ease showed profound improvement following ONSD. Unexpectedly, pa¬ tient 2 demonstrated improvement in visual acuity in the fellow eye that was not operated on and that had been affected 2 years previously by NAION. Sergott et al1 reported improvement in 12 of 14 eyes with progressive NAION and in one of three patients with nonprogressive NAION; two pa¬ tients demonstrated improvement in the fellow eye that was not operated
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In contrast to Sergott et al, we utilized standardized ETDRS charts, lighting, and refraction techniques to measure visual acuity. As opposed to routine Snellen acuity charts, ETDRS charts reproducibly measure visual on.
in patients, especially those with poor central vision.8 Our experi¬ ence confirms and expands the findings of Sergott et al, lending further sup¬ port to the possible beneficial effect of ONSD on visual acuity in patients with
acuity
NAION.4 Six of seven patients showed expan¬ sion of visual fields on Goldmann peri¬ metry, three of whom also exhibited
increased foveal sensitivity on Hum¬ phrey automated perimetry; only two demonstrated an increase in MD great¬ er than 5 dB. Still, in the remaining four patients, Humphrey perimetry proved to be unreliable. This under¬ scores the difficulty of the use of auto¬ mated perimetry in an elderly popula¬ tion further limited by poor visual acuity and central fixation.
Sergott
et al4 did not comment
on
other visual function measurements, such as color vision and changes in the
RAPD. In our series, color vision im¬ in only three patients and cor¬ related with improvement in the RAPD and foveal sensitivity. These are all known measures of optic nerve function. One would expect some re¬ covery of color vision and reduction in the RAPD in all our patients, in light of the visual acuity and visual field improvement11; however, such a dissociation of optic nerve function measurements is often seen in optic neuropathies, especially optic neuri¬
proved
tis.6 Furthermore, present techniques
for testing color vision and RAPD may fail to detect lesser degrees of im¬
provement.
Complications
associated with central retinal artery
ONSD, including occlusion, tonic pupils, intraoperative
bleeding from trauma to posterior cili¬ ary arteries, and transient diplopia, were
not encountered in
None of
our
our
series.12
patients developed
any
worsening of vision in the first 72 to 96 hours postoperatively. In contrast, Sergott et al4 reported two thirds of patients ultimately improving actually worsened within the first 4 days after surgery.
Sergott et al4 attempted to provide pathophysiologic rationale for the success of ONSD in papilledema and °
a
progressive NAION. Based on Hayreh's13 work establishing optic nerve ischemia
as
the
cause
for visual loss in
papilledema, they hypothesized that ONSD may correct optic nerve isch¬ emia and thereby reverse visual loss due to papilledema and progressive NAION. In the peripheral nerve, mild elevations in perineural pressure im-
pair rapid axonal transport. The im¬ paired transport is secondary to isch¬ emia; reduction of perineural pressure reverses ischemia and improves axonal transport.14 By extrapolating to the optic nerve, Sergott et al suggested that progressive visual loss after an
initial ischemie event in NAION could be due to interference with rapid axoplasmic transport produced by CSF pressure within the anatomically re¬ stricted confines of the perineural optic nerve space. Under normal circum¬ stances, this perineural pressure may not interfere with optic nerve blood flow. However, in optic nerves affect¬ ed by a vasoocclusive process, normal CSF pressure might additionally com¬ promise vascular perfusion and impair axoplasmic transport. Drainage of the CSF might allow recovery of the fast axoplasmic transport with subsequent improvement in visual function.4:> This explanation applies to nonpro¬ gressive and progressive NAION; in both types, reduction of perineural pressure could improve a reversible component of ischemia and blocked axoplasmic transport in the presence of irreversible ischemia.4 The revers¬ ible nature of axonal dysfunction in the optic nerve may, in part, be explained by a compensatory shift from aerobic to anaerobic glycolysis that takes place in ischemie axons in the central and peripheral nervous systems.1' This metabolic adaptation may be responsi¬ ble for the delay of irreversible tissue damage.10 Such a mechanism may be operative in the protection of the isch¬ emie optic nerve until ONSD produces reperfusion and improves function.5
While
gott
compelling, the theories of Ser¬ al4" are not yet universally
et
accepted.1617 Until the
gott
et
more
recent
report of Ser¬
al,4 NAION was generally con¬
sidered to be an untreatable and irre¬ versible cause of visual loss.1'218 Only one previous report describes substan¬ tial spontaneous improvement in one third of patients with NAION.19 With the exception of this report, two large studies indicate that spontaneous im¬
provement rarely occurs.218 Still,
we
recently observed one patient with nonprogressive NAION whose visual acuity spontaneously improved within
2 months from 20/400 to 20/60. Fur¬ thermore, all natural history studies in the literature are hampered by lack of standardized visual function measure¬ ments. The natural history of NAION re¬ mains controversial due to the absence of a well-designed prospective natural history study. The results of such a study are sorely needed. If the natural history based on historical controls is
truly as grim as generally believed, no prospective clinical trial to test the efficacy of ONSD in NAION is needed. However, as mentioned above, the lit¬ erature does not uniformly embrace
the lack of spontaneous improvement.19 Therefore, a randomized clinical trial of ONSD for NAION is needed to assess treatment efficacy and safety of ONSD, while definitively describing the natural history of NAION. This work was supported in part by grant R21 EY07766 from the National Institutes of Health, Bethesda, Md.
References 1.
athy.
Hayreh SS. Anterior Ischemic Optic NeuropNew York, NY: Springer-Verlag NY Inc;
1975. 2. Boghen DR, Glaser JS. Ischaemic optic neuropathy: the clinical profile and natural history. Brain. 1975;98:689-708. 3. Borchert M, Lessell S. Progressive and recurrent non-arteritic anterior ischemic optic neuropathy. Am J Ophthalmol. 1988;106:443-449. 4. Sergott RC, Cohen MS, Bosley TM, Savino PJ, et al. Optic nerve decompression may improve the progressive form of non-arteritic ischemic optic neuropathy. Arch Ophthalmol. 1989;107:1743\x=req-\ 1754. 5. Sergott RC, Savino PJ, Bosley TM. Optic nerve sheath decompression: a clinical review and proposed pathophysiologic mechanism. Aust N Z J Ophthalmol. In press. 6. Miller NR. Anterior ischemic optic neuropathy. In: Walsh and Hoyt's Clinical Neuro-Ophthalmology. 4th ed. Baltimore, Md: Williams & Wilkins; 1982:212-226.
7. Beck RW, Savino PJ, Repka MX, Schatz NJ, Sergott RC. Optic disc structure in anterior ischemic optic neuropathy. Ophthalmology. 1984;
91:1334-1337. 8. Ferris FL III, Sperduto RD. Standardized illumination for visual acuity testing in clinical research. Am J Ophthalmol. 1982;94:97-98. 9. Thompson HS, Corbett JJ, Cox TA. How to measure the relative afferent pupillary defect. Surv Ophthalmol. 1981;26:39-42. 10. Sergott RC, Savino PJ, Bosley TM. Modified optic nerve decompression provides long-term visual improvement in pseudotumor cerebri. Arch
Ophthalmol. 1988;106:1384-1390. 11. Thompson HS, Montague P,
Cox TA, Corbett JJ. Relationship between visual acuity, papillary defect, and visual field loss. Am J Ophthalmol.
1982;93:681-688.
12. Keltner JL. Optic nerve sheath decompression. Arch Ophthalmol. 1988;106:1365-1369. 13. Hayreh SS. Pathogenesis of oedema of the optic disc. Doc Ophthalmol. 1968;24:289-411.
Downloaded From: by a Universite Laval User on 12/17/2017
14. Dahlen LB, Rydevik B, McLean WG, Sjorstrand J. Changes in fast axonal transport during experimental nerve compression at low pressures. Exp Neurol. 1984;84:29-36. 15. Sladky JT, Greenberg JH, Brown MJ. Regional perfusion in normal and ischemic rat sciatic nerves. Ann Neurol. 1985;17:191-195. 16. Hayreh SS. The role of optic nerve sheath fenestration in management of anterior ischemic optic neuropathy. Arch Ophthalmol. 1990;108: 1063-1064. 17. Wilson WB. Does optic nerve sheath decompression help progressive ischemic optic neuropathy? Arch Ophthalmol. 1990;108:1065-1066. 18. Repka MX, Savino PJ, Schatz NJ, Sergott RC. Clinical profile and long term implications of anterior ischemic optic neuropathy. Am J Ophthalmol. 1983;98:741-746. 19. Ellenberger C, Burde RM, Keltner JC. Acute optic neuropathy: treatment with diphenylhydantoin. Arch Ophthalmol. 1974;91:435-438.
Optic
Shalom E. Kelman, MD, Michael J. Elman, MD
Optic nerve sheath decompression performed in seven patients with nonarteritic anterior ischemic optic neuropathy. Visual function was evaluated by measurement of visual acuity with \s=b\
was
Early Treatment Diabetic Retinopathy Study charts, color vision testing, quantitation of relative afferent pupillary defects with neutral-density filters, and Goldmann and Humphrey perimetry. Visual acuity improved markedly in all patients (at least doubling of the visual angle); the peripheral visual field expanded by at least 20\s=deg\(as measured by Goldmann perimetry) in six patients. Three patients also experienced marked improvement in color vision, relative afferent pupillary defect, and foveal sensitivity. Our experience supports the possible beneficial effect of optic nerve sheath decompression in patients with nonarteritic anterior ischemic optic neuropathy. (Arch Ophthalmol. 1991;109:667-671) standardized
weeks after onset of symptoms."3 The dynamic, evolving visual loss seen in progressive NAION may relate to pro¬ gressive ischemia and blocked axoplasmic transport.4,5 See also pp 612 and 613.
Sergott et al4 have reported that 12 of 14 patients with progressive NAION showed marked improvement in visual function following optic nerve sheath decompression (ONSD) with ly¬ sis of subarachnoid adhesions. Encour¬ aged by these results, we performed ONSD in five consecutive patients with progressive NAION and two pa¬ tients with nonprogressive NAION. Comprehensive visual function studies were performed in all patients in a standardized fashion. PATIENTS AND METHODS
study comprised four men and three whose ages ranged from 55 to 85 years (mean, 69 years) (Table). All patients presented with painless decreased central visual acuity and visual field defects typical The
"M" onarteritic ischemie
optic neuropathy (NAION) typically presents with sudden, often profound visual loss from anterior optic nerve infarction.1 In up to 25% of affected patients, visual acuity continues to worsen 1 to 4 Accepted for publication December 4, 1990. From the Neuro-Ophthalmology Service (Dr Kelman) and the Clinical Trials and Epidemiology Unit (Dr Elman), Department of Ophthalmology, University of Maryland School of Medicine, Baltimore.
Reprint requests to the Neuro-Ophthalmology Service, Department of Ophthalmology, University of Maryland Hospital, 22 S Greene St, Baltimore, MD 21201 (Dr Kelman).
women
of NAION.1' Disc edema and peripapillary hemorrhages were present in the involved eye. Slit-lamp examination revealed no evi¬ dence of inflammatory cells in the anterior segment or vitreous. Vasculitis screening, including determination of a Westergren erythrocyte sedimentation rate, yielded normal findings. None of the patients had a prior history of visual loss consistent with optic neuritis or a history of neurologic disease consistent with multiple sclerosis. Five patients developed progressive worsening of visual acuity and visual field
Downloaded From: by a Universite Laval User on 12/17/2017
loss 1 to 3 weeks after the onset of symp¬ toms. In contrast, two patients experienced immediate, profound visual loss to their preoperative level without progressive loss of visual function. Bilateral congenital anomalous discs' (lack of physiologic central cup) were noted in six patients. Patient 2 had experienced NAION in the fellow eye 2 years before the current episode. Follow-up ranged from 3 to 10 months (mean, 7 months). The remaining clinical features are summarized in the Table. The best corrected visual acuity was mea¬ sured with the Early Treatment Diabetic Retinopathy Study (ETDRS) charts with standardized lighting." When worse than 5/200, visual acuity was graded as counting fingers, hand motions, or light perception. Color vision was assessed by Hardy-RandRittler color plates. Relative afferent pupil¬ lary defects (RAPDs) were quantified with neutral-density filters ranging in strength from 0.3 to 3.0 log units.9 A certified techni¬ cian measured ETDRS visual acuity, per¬ formed Goldmann peripheral visual field testing, and monitored Humphrey program 24-2 automated perimetry. Visual acuity was considered improved when (1) the visual angle doubled (ie, im¬ proved by three or more lines, eg, from 20/100 to" 20/50) or (2) it increased by at least one level of central visual function when visual acuity was less than 5/200 (eg, from hand motions to counting fingers at 1 ft). Assessment of visual field improvement was based on an expansion of at least 20° of the V-4-e isopter on Goldmann perimetry or an increase of 5 dB of mean deviation (MD) on automated fields. RESULTS
Surgical Findings All patients underwent modified ONSD with lysis of subarachnoid adhe-
Clinical Features of Patients With Nonarteritic
Eye That Was Acutely No./Age,
Involved and Underwent
y Sex
Surgery
/75/F
OD
Patient
Interval From
Ophthalmologic Medical
History
Stable angina
History Congenital anomalous discs OU; cataract extraction OD 4 wk before visual loss NAION OS 2 y prior; congenital anomalous discs OU
2/66/M
OD
Hypertension
3/75/M
OD
Non-insulin dependent diabetes for 5 y;
4/63/F
OS
receiving oral agents for 4y Hypertension
5/85/F
OD
Labile
hypertension
Congenital
Onset to
Surgery,
Preoperative VA, OD, OS
d
Postoperative VA, OD, OS
15
CF, 20/20
20/100, 20/20
40
CF, 20/800
20/200, 20/400
CF, 20/25
5/160, 20/25
20/25, CF
20/25, 20/125
CF, 20/40
20/200, 20/40
20/400, 20/20
20/80, 20/20
anomalous
discs OU
None
Congenital anomalous
16
discs OU 6/55/M
OD
Congenital anomalous
None
discs OU
Cataract OS; congenital HM, 20/80 Right-sided pontine infarct anomalous discs OU 3 y previously; hypertension for 10 y VA indicates visual acuity; RAPD, relevant afferent pupillary defect; CF, counting fingers at 1 ft; F, foveal sensitivity (in decibels); MD, tions; and PCA, posterior ciliary artery. fPlus sign indicates progressive disease; minus sign, nonprogressive disease. OD
sions by the same surgeon (S.E.K.) according to the method described by Sergott et al.1" Surgery was performed between 14 and 40 days after the onset
of visual symptoms. No correlation found between the timing of sur¬ gery and visual outcome. At surgery, mild distention of the optic nerve sheaths was noted, al¬ though not to the extent we have observed in pseudotumor cerebri. In patient 7, a medial posterior ciliary artery was markedly sclerotic and ap¬ peared to be occluded; in the remaining cases, the vessels overlying the optic nerve sheath appeared to be normal. Incision of the meningeal sheath re¬ sulted in the release of moderate amounts of cerebrospinal fluid (CSF), sometimes interspersed with small lip¬ id droplets.4 In three patients, the consistency of the arachnoid appeared to be thickened and gumlike (Table). An arachnoid biopsy was attempted without success. There were no surgi¬ cal complications. was
Visual
All
Recovery
patients showed marked
im¬
provement in visual acuity followingsurgery (Table, Fig 1). Patients 1 and
experienced improved vision within the first week after surgery. In the remaining five patients, visual recov¬ ery usually began by the third postop¬ erative week, and vision continued to improve during the next 8 weeks. The results of preoperative and postoperative color vision testing,
2
20/160, 20/70
mean
deviation; HM, hand
mo¬
RAPD measurements, and visual field
testing are recorded in the Table. The peripheral Goldmann visual fields im¬ proved in six patients. The three pa¬
tients in whom color vision test¬ ing showed improvement also demon¬ strated improvement of the RAPD and foveal sensitivity as well as expansion of Goldmann visual fields. In the remaining four patients, automated fields were deemed unreliable because of excessive fixation losses or high false-positive and false-negative re¬ sponses. These four patients also failed to show improvement in RAPD and color vision, even though visual acuity improved. However, the Goldmann vi¬ sual field expanded markedly in three of these four patients. The clinical courses of three repre¬ sentative cases are presented in detail below. Patient 1
75-year-old hypertensive white noted sudden visual blurring in her right eye. Four weeks earlier, she had undergone an uncomplicated ex¬ tracapsular cataract extraction with a posterior chamber intraocular lens im¬ plant. Two weeks postoperatively, vi¬ sual acuity was 20/25 OD; 2 weeks later, the patient noticed increased blurring of vision, which progressively worsened during the next week. She was examined 9 days after the onset of
Fig 1 Preoperative and postoperative visu¬ al acuities in seven patients treated with optic nerve sheath decompression for nonarteritic anterior ischemie optic neuropathy. The 45° solid line represents no change in visual acu¬ ity. HM indicates hand motions; CF, counting —
.
fingers.
A
woman
her initial symptom of blurred vision. Visual acuity measured 20/400 OD and 20/20 OS. An RAPD and an inferior
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altitudinal visual field defect were not¬ ed. The optic disc was swollen with streak peripapillary hemorrhages. The patient was referred to the University of Maryland (Baltimore) Neuro-Ophthalmology Service for con¬ sideration of ONSD. In just 2 days, distance visual acuity in the right eye declined to counting fingers at 1 ft. She could not identify any Hardy-RandRittler pseudoisochromatic color plates with the right eye. An RAPD, measur¬ ing 0.9 log units, was present in the right eye. The markedly elevated right
Anterior Ischemie
Optic Neuropathy (NAION)* Humphrey Color
Progressivet
Preoperatively
Visual Field
Postoperatively
Color
(Change)
Preoperatively
Postoperatively
0.9
0.3
3/10
RAPD
(Change)
Goldmann Visual Field + 25°
Preoperalively F=0 MD -20.8 =
Postop¬ eratively
Operative Findings
10
=
/
0.3
0.3
+30°
Not reliable
Thick arachnoid
0/10
0/10
2.1
2.1
No change
Not reliable
Thick arachnoid
F MD
=
0
=
-17.11
/ +0.9
0/10
0/10
+ 30°
1.2
1.2
+ 50°
F MD
=
( 25.3 -
10
F=13 MD -15.25 =
Not reliable
1/10
mo
F=27 MD -9.52
/
+0.9
Follow-up,
Thick arachnoid
F
=
22
MD
=
-18.3
Not reliable
10
10
PCA occlusion
optic disc was surrounded by peripapil¬ lary hemorrhages. The left optic disc was small and cupless. Goldmann visu¬
al fields demonstrated a relative inferi¬ or altitudinal scotoma involving central fixation. Humphrey program 24-2 pe¬ rimetry revealed a foveal sensitivity of 0 dB and global depression with an MD of -20.8 dB (Fig 2, left). An uncomplicated right-sided ONSD with lysis of subarachnoid adhesions was performed. By the third postoper¬ ative day, the patient noted some sub¬ jective visual improvement; she now could identify faces, which she was unable to recognize preoperatively. One week postoperatively, visual acu¬ ity improved to 20/100. Five of 10 color plates were correctly identified. Her RAPD improved to 0.3 log units. Auto¬ mated perimetry showed improvement on both MD and foveal sensitivity (Fig 2, right). Goldmann visual fields ex¬ panded by 25° to the V-4-e isopter. Ten months postoperatively, visual acuity remains stable at 20/100. Optic disc pallor developed superiorly, and disc edema completely resolved. Patient 2
A
man was referred be¬ of acute onset of blurred vision in his right eye. Seven years earlier, he experienced a sudden loss of vision in his left eye following cataract ex¬ traction, attributed to ischemie optic neuropathy. The patient was first seen 7 days after the onset of his symptoms; visual acuity was 20/100 OD. He was
66-year-old
cause
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Fig 2. Left, Preoperative pattern deviation depiction of the Humphrey 24-2 visual field in patient 1. Mean deviation was 20.8 dB, and foveal sensitivity was zero. Right, Postoperative pattern deviation depiction of the Humphrey 24-2 visual field in patient 1. Mean deviation was 9.52 dB. and foveal sensitivity was 27 dB. Note increased sensitivity, especially supranasally. —
-
-
treated with oral prednisone, starting at 60 mg/d and tapering over 2 weeks to 5 mg/d. During this time, despite treatment, the patient noted progres¬ sive worsening of his vision. He was referred to the University of Maryland Hospital 3 weeks after the onset of his symptoms. Visual acuity measured counting fingers in the right eye at 1 ft and 20/800 OS. On color plate testing, the patient identified zero of 10 plates with both eyes. An afferent pupillary defect measuring 0.3 log units was present in the right eye. Goldmann visual fields showed marked constric¬ tion of the V-4-e isopter in both eyes. A fundus examination revealed supe¬ rior disc swelling, with a flame-shaped hemorrhage in the right eye. The markedly pale optic disc in the fellow eye also lacked a central cup. We performed an uncomplicated right-sided ONSD with lysis of subarachnoid adhesions. One day after sur¬ gery, the patient noted improvement in brightness and color vision. Visual acuity improved to 20/200 at postoper¬ ative week 1. Five months postopera¬ tively, the patient's visual acuity is maintained at 20/200 OD; visual acuity in the eye not operated on has im¬ proved to 20/400. The optic disc edema has evolved into disc pallor, and visual fields have expanded in both eyes. Patient 6
A 55-year-old computer programmer noted the acute, painless onset of a central blur in his right eye. When the patient was initially seen 15 days after the onset of symptoms, visual acuity was 20/400 OD and 20/20 OS. On color plate testing, one of 10 plates was identified with the right eye and 10 of 10 plates with the left eye. A 1.5-log unit RAPD was measured in the right eye. Fundus examination revealed a swollen superior optic disc with a cot¬ ton-wool spot off the disc at the 5-o'clock position. The optic disc in the fellow eye had a congenital anomaly without a central cup. Goldmann visual fields in the right eye demonstrated marked depression of the entire field, especially inferiorly. Foveal sensitivity was 6 dB (Fig 3, left). The patient did not experience any subjective worsen¬ ing from the onset of symptoms. One month following ONSD sur¬ gery, visual acuity had improved to 20/80 OD. Color plate testing results improved to seven of 10 plates identi¬ fied with the right eye. The RAPD had decreased to 0.6 log units. Five months following surgery, the patient has maintained a visual acuity of 20/80 OD, and eight of 10 color plates were iden¬ tified correctly; a 0.6-log unit RAPD
Fig 3.—Left, Preoperative pattern deviation depiction of the Humphrey 24-2 visual field in patient 6. Mean deviation was -24.3 dB, and foveal sensitivity 6 dB. Right, Postoperative pattern deviation depiction of the Humphrey 24-2 visual field in patient 6. Mean deviation was 18.3 dB, and foveal sensitivity was 22 dB. Note the marked increase in sensitivity in the superior field. -
remains in the right eye. Optic disc edema resolved into diffuse pallor. Fo¬ veal sensitivity has increased to 22 dB. Mean deviation has improved from -24.3 dB to -18.3 dB, with marked improvement in the sensitivity of the superior visual field (Fig 3, right). COMMENT
Optic nerve sheath decompression, with release of perineural CSF, mark¬ edly improved visual acuity in all seven of our patients with NAION. Five of the patients experienced progressive visual loss before surgery. Even the two patients with nonprogressive dis¬ ease showed profound improvement following ONSD. Unexpectedly, pa¬ tient 2 demonstrated improvement in visual acuity in the fellow eye that was not operated on and that had been affected 2 years previously by NAION. Sergott et al1 reported improvement in 12 of 14 eyes with progressive NAION and in one of three patients with nonprogressive NAION; two pa¬ tients demonstrated improvement in the fellow eye that was not operated
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In contrast to Sergott et al, we utilized standardized ETDRS charts, lighting, and refraction techniques to measure visual acuity. As opposed to routine Snellen acuity charts, ETDRS charts reproducibly measure visual on.
in patients, especially those with poor central vision.8 Our experi¬ ence confirms and expands the findings of Sergott et al, lending further sup¬ port to the possible beneficial effect of ONSD on visual acuity in patients with
acuity
NAION.4 Six of seven patients showed expan¬ sion of visual fields on Goldmann peri¬ metry, three of whom also exhibited
increased foveal sensitivity on Hum¬ phrey automated perimetry; only two demonstrated an increase in MD great¬ er than 5 dB. Still, in the remaining four patients, Humphrey perimetry proved to be unreliable. This under¬ scores the difficulty of the use of auto¬ mated perimetry in an elderly popula¬ tion further limited by poor visual acuity and central fixation.
Sergott
et al4 did not comment
on
other visual function measurements, such as color vision and changes in the
RAPD. In our series, color vision im¬ in only three patients and cor¬ related with improvement in the RAPD and foveal sensitivity. These are all known measures of optic nerve function. One would expect some re¬ covery of color vision and reduction in the RAPD in all our patients, in light of the visual acuity and visual field improvement11; however, such a dissociation of optic nerve function measurements is often seen in optic neuropathies, especially optic neuri¬
proved
tis.6 Furthermore, present techniques
for testing color vision and RAPD may fail to detect lesser degrees of im¬
provement.
Complications
associated with central retinal artery
ONSD, including occlusion, tonic pupils, intraoperative
bleeding from trauma to posterior cili¬ ary arteries, and transient diplopia, were
not encountered in
None of
our
our
series.12
patients developed
any
worsening of vision in the first 72 to 96 hours postoperatively. In contrast, Sergott et al4 reported two thirds of patients ultimately improving actually worsened within the first 4 days after surgery.
Sergott et al4 attempted to provide pathophysiologic rationale for the success of ONSD in papilledema and °
a
progressive NAION. Based on Hayreh's13 work establishing optic nerve ischemia
as
the
cause
for visual loss in
papilledema, they hypothesized that ONSD may correct optic nerve isch¬ emia and thereby reverse visual loss due to papilledema and progressive NAION. In the peripheral nerve, mild elevations in perineural pressure im-
pair rapid axonal transport. The im¬ paired transport is secondary to isch¬ emia; reduction of perineural pressure reverses ischemia and improves axonal transport.14 By extrapolating to the optic nerve, Sergott et al suggested that progressive visual loss after an
initial ischemie event in NAION could be due to interference with rapid axoplasmic transport produced by CSF pressure within the anatomically re¬ stricted confines of the perineural optic nerve space. Under normal circum¬ stances, this perineural pressure may not interfere with optic nerve blood flow. However, in optic nerves affect¬ ed by a vasoocclusive process, normal CSF pressure might additionally com¬ promise vascular perfusion and impair axoplasmic transport. Drainage of the CSF might allow recovery of the fast axoplasmic transport with subsequent improvement in visual function.4:> This explanation applies to nonpro¬ gressive and progressive NAION; in both types, reduction of perineural pressure could improve a reversible component of ischemia and blocked axoplasmic transport in the presence of irreversible ischemia.4 The revers¬ ible nature of axonal dysfunction in the optic nerve may, in part, be explained by a compensatory shift from aerobic to anaerobic glycolysis that takes place in ischemie axons in the central and peripheral nervous systems.1' This metabolic adaptation may be responsi¬ ble for the delay of irreversible tissue damage.10 Such a mechanism may be operative in the protection of the isch¬ emie optic nerve until ONSD produces reperfusion and improves function.5
While
gott
compelling, the theories of Ser¬ al4" are not yet universally
et
accepted.1617 Until the
gott
et
more
recent
report of Ser¬
al,4 NAION was generally con¬
sidered to be an untreatable and irre¬ versible cause of visual loss.1'218 Only one previous report describes substan¬ tial spontaneous improvement in one third of patients with NAION.19 With the exception of this report, two large studies indicate that spontaneous im¬
provement rarely occurs.218 Still,
we
recently observed one patient with nonprogressive NAION whose visual acuity spontaneously improved within
2 months from 20/400 to 20/60. Fur¬ thermore, all natural history studies in the literature are hampered by lack of standardized visual function measure¬ ments. The natural history of NAION re¬ mains controversial due to the absence of a well-designed prospective natural history study. The results of such a study are sorely needed. If the natural history based on historical controls is
truly as grim as generally believed, no prospective clinical trial to test the efficacy of ONSD in NAION is needed. However, as mentioned above, the lit¬ erature does not uniformly embrace
the lack of spontaneous improvement.19 Therefore, a randomized clinical trial of ONSD for NAION is needed to assess treatment efficacy and safety of ONSD, while definitively describing the natural history of NAION. This work was supported in part by grant R21 EY07766 from the National Institutes of Health, Bethesda, Md.
References 1.
athy.
Hayreh SS. Anterior Ischemic Optic NeuropNew York, NY: Springer-Verlag NY Inc;
1975. 2. Boghen DR, Glaser JS. Ischaemic optic neuropathy: the clinical profile and natural history. Brain. 1975;98:689-708. 3. Borchert M, Lessell S. Progressive and recurrent non-arteritic anterior ischemic optic neuropathy. Am J Ophthalmol. 1988;106:443-449. 4. Sergott RC, Cohen MS, Bosley TM, Savino PJ, et al. Optic nerve decompression may improve the progressive form of non-arteritic ischemic optic neuropathy. Arch Ophthalmol. 1989;107:1743\x=req-\ 1754. 5. Sergott RC, Savino PJ, Bosley TM. Optic nerve sheath decompression: a clinical review and proposed pathophysiologic mechanism. Aust N Z J Ophthalmol. In press. 6. Miller NR. Anterior ischemic optic neuropathy. In: Walsh and Hoyt's Clinical Neuro-Ophthalmology. 4th ed. Baltimore, Md: Williams & Wilkins; 1982:212-226.
7. Beck RW, Savino PJ, Repka MX, Schatz NJ, Sergott RC. Optic disc structure in anterior ischemic optic neuropathy. Ophthalmology. 1984;
91:1334-1337. 8. Ferris FL III, Sperduto RD. Standardized illumination for visual acuity testing in clinical research. Am J Ophthalmol. 1982;94:97-98. 9. Thompson HS, Corbett JJ, Cox TA. How to measure the relative afferent pupillary defect. Surv Ophthalmol. 1981;26:39-42. 10. Sergott RC, Savino PJ, Bosley TM. Modified optic nerve decompression provides long-term visual improvement in pseudotumor cerebri. Arch
Ophthalmol. 1988;106:1384-1390. 11. Thompson HS, Montague P,
Cox TA, Corbett JJ. Relationship between visual acuity, papillary defect, and visual field loss. Am J Ophthalmol.
1982;93:681-688.
12. Keltner JL. Optic nerve sheath decompression. Arch Ophthalmol. 1988;106:1365-1369. 13. Hayreh SS. Pathogenesis of oedema of the optic disc. Doc Ophthalmol. 1968;24:289-411.
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14. Dahlen LB, Rydevik B, McLean WG, Sjorstrand J. Changes in fast axonal transport during experimental nerve compression at low pressures. Exp Neurol. 1984;84:29-36. 15. Sladky JT, Greenberg JH, Brown MJ. Regional perfusion in normal and ischemic rat sciatic nerves. Ann Neurol. 1985;17:191-195. 16. Hayreh SS. The role of optic nerve sheath fenestration in management of anterior ischemic optic neuropathy. Arch Ophthalmol. 1990;108: 1063-1064. 17. Wilson WB. Does optic nerve sheath decompression help progressive ischemic optic neuropathy? Arch Ophthalmol. 1990;108:1065-1066. 18. Repka MX, Savino PJ, Schatz NJ, Sergott RC. Clinical profile and long term implications of anterior ischemic optic neuropathy. Am J Ophthalmol. 1983;98:741-746. 19. Ellenberger C, Burde RM, Keltner JC. Acute optic neuropathy: treatment with diphenylhydantoin. Arch Ophthalmol. 1974;91:435-438.
