CLINICAL FEATURES OF
NON-ARTERITIC AND ARTERITIC AION

We have described these in detail elsewhere.^{9,11,23,30,31,36,40} AION usually presents with classical symptoms and signs. Following is a very brief account of the clinical features of AION:

AGE DISTRIBUTION:

Arteritic AION is a disease of patients aged 55 years and older.^46,48
Non-arteritic AION can occur at any age - no age is immune from non-arteritic AION - although most often patients are middle aged and elderly, about 10% of the patients are young (i.e. under the age of 45 years - our youngest patient has been 11 years old);⁴⁴ thus, the prevalent impression that non-arteritic AION is a disease of the elderly only and does not occur in the young persons is not correct.

GENDER DISTRIBUTION:

Arteritic AION is almost three times more common in women than in men.^46,48
By contrast, non-arteritic AION usually affects men and women almost equally.²⁹

SYMPTOMS:

In non-arteritic AION there is a sudden and painless deterioration of vision, usually discovered on waking in the morning,⁴⁷ and involving mostly the lower part of the visual field in one eye. Later on many of these patients complain of marked sensitivity to bright light, particularly those who have had bilateral AION.
In arteritic AION, we found that about one third of patients complained of transient blurring or loss of vision in the involved eye before they lost the vision permanently in that eye; loss of vision can occur at any time of the day, although more often during the night.⁴⁸

VISUAL ACUITY:

In non-arteritic AION this may vary from better than 20/20 (6/6) to marked loss of vision, depending upon the part of the ONH involved by the AION.^23,45
By contrast, in arteritic AION the visual loss usually is much worse, so that a high proportion of the eyes are either completely blind or have extremely poor vision, although about 20% of them can still see 20/20.⁴⁸
Thus, normal visual acuity does not rule out AION, and visual acuity is a poor test for detection of both types of AION.

VISUAL FIELDS:

This is investigated by perimetry. Perimetry is the most important visual function test to evaluate the visual loss in AION. Perimetry usually shows partial or complete loss of vision in one or the other part of the field of vision.⁴⁵ The most common loss of vision is towards the nose (Fig. 3-A); next common is in the lower half (Fig. 9-B), and less common a blind spot in the center, although less frequently other types of field defects can occur.^36,45 When a patient has lost vision in the lower half of the field of vision (Fig. 3-B), particularly when both eyes are involved, although straight ahead she/he may be able to see 20/20, she/he cannot see anything below the horizontal level so that she/he does not know where she/he is walking, has difficulty seeing to go down steps, tying her/his shoes without tilting the head down, and driving. All these are extremely disabling. So that some of these patients, in spite of seeing 20/20, may be legally blind.

Fig. 3: Two examples of fields of vision plotted with a Goldmann perimeter (using targets I2e - red, I4e - blue, and V4e - purple) in non-arteritic AION (Reproduced from Hayreh23):
[For a larger view of image, click on the image.]	[For a larger view of image, click on the image.]
A. Right eye field of vision shows loss of inner and lower field of vision towards the nose.	B. Left eye field of vision shows loss of the entire lower half of field of vision.

OPHTHALMOSCOPY:

On ophthalmoscopic examination, during the initial stages, the optic disc shows edema which may be more marked in one part of the disc than the other (Figs. 4, 5-B, 6, 7, 8-A). Frequently there are splinter hemorrhages at the disc margin (Fig. 4). We have found that in 69% of arteritic AION eyes, the optic disc swelling has a characteristic chalky white appearance (Fig. 6).⁴⁸ Gradually the swelling of the optic disc starts to subside and become pale. Within 2-3 months the optic disc swelling resolves spontaneously and the disc becomes pale either in only one region or all over (Figs. 5-C, 7-B, 8-B).^{9,11,18,30,36} In non-arteritic AION the fellow, normal optic disc shows either no cup or a very small cup, which is usually not the case in arteritic AION.³
In diabetics, during the initial stages, the optic disc swelling is usually associated with prominent, dilated vessels over the disc, and much more numerous retinal hemorrhages around the optic disc than in non-diabetics^39,54 (Fig. 7-A, 8-A) - these findings may easily be mistaken for proliferative diabetic retinopathy associated with optic disc new blood vessel formation and unnecessarily treated with laser (panretinal photocoagulation).⁵⁴ When the optic disc swelling resolves spontaneously, these prominent and dilated disc vessels and retinal hemorrhages also resolve spontaneously (Fig. 7-B, 8-B). If laser treatment has been administered, this spontaneous resolution may erroneously be attributed to it!

Fig. 4: Fundus photographs of right eye showing optic disc swelling (edema) and a splinter hemorrhage at the optic disc margin during the early stages of non-arteritic AION. (Reproduced from Hayreh30)

[For a larger view of this picture, click on image]

Fig. 5: Fundus photographs of left eye of a patient with non-arteritic AION, who was being following in our clinic for non-arteritic AION in the right eye before he developed the same in the left eye. (Reproduced from Hayreh30)
[For a larger view of this picture, click on image]	[For a larger view of this picture, click on image]	[For a larger view of this picture, click on image]
A. Normal optic disc before onset of non-arteritic AION.	B. Optic disc edema during early stages of non-arteritic AION.	C. Pale color (atrophy) of the optic disc during later stages.

Fig. 6: Fundus photograph of right eye with arteritic AION showing during the early phase the typical chalky white optic disc edema. (Reproduced from Hayreh9)

[For a larger view of this picture, click on image]

Fig. 7: Fundus photographs of right eye of a diabetic patient with non-arteritic AION showing:
[For a larger view of this picture, click on image]	[For a larger view of this picture, click on image]
A. During early stages optic disc edema involving the superior temporal part of the optic disc and prominent vessels in that region.	B. During later stages: pale color (atrophy) in the upper half of the optic disc - more marked in the temporal than the nasal part, and spontaneous resolution of the prominent blood vessels on the optic disc.

Fig. 8: Fundus photographs of right eye of a diabetic patient with non-arteritic AION showing (Reproduced from Hayreh et al.54):
[For a larger view of this picture, click on image]	[For a larger view of this picture, click on image]
A. During early stage with optic disc edema with prominent blood vessels on the disc and many retinal hemorrhages.	B. During later stage with pale color (optic atrophy) and spontaneous resolution of prominent blood vessels on the optic disc as well as hemorrhages.

FLUORESCEIN FUNDUS ANGIOGRAPHY:

In non-arteritic AION, during the very early stages of the disease, angiography may show filling defects in the optic disc, peripapillary choroid and/or choroidal watershed zones (Fig. 9-A).^9,11,20,25
In arteritic AION this test is extremely helpful in making the diagnosis because it shows that the choroid and the optic disc in the area supplied by the involved posterior ciliary artery do not fill (Fig. 9-B).^{9,11,20,25,49} During the late phase of angiography, the disc stains with fluorescein; this is a non-specific finding in both types of AION.

Fig. 9: Fluorescein fundus angiograms of two eyes during the early stages of AION, showing no circulation in parts of the choroid and optic disc (dark areas correspond to absence of filling by fluorescein dye):
[For a larger view of this picture, click on image]	[For a larger view of this picture, click on image]
A. In right eye with non-arteritic AION. (Reproduced from Hayreh20)	B. In left eye with arteritic AION. (Reproduced from Hayreh15)

Contents | Back | Next