Mewds Azoor Acute Idiopathic Blind Spot Enlargement Syndrome

Multiple evanescent white dot syndrome (MEWDS) [4], acute zonal outer retinopathy (AZOOR) [5], and acute idiopathic blind spot enlargement syndrome [6] have several similar ophthalmological and demographic findings: unilateral, blurred vision, multiple paracentral scotomas usually including a temporal scotoma, photopsia, and blind spot enlargement; and it affects young women. These symptoms usually develop soon after a flu-like illness. Among these disorders, only MEWDS has ophthalmoscopic abnormalities, which include clusters of tiny white or light-orange dots in the foveola and multiple small, often poorly defined gray-white patches at the level of the RPE and outer retina (Fig. 3.20). The visual function and fundus abnormalities may return to normal in 7-10 weeks. It is likely that most patients reported as having the acute idio-pathic blind spot enlargement syndrome and AZOOR probably had MEWDS, and the white lesions were either overlooked or had faded by the time of the examination.

The common functional abnormality of these disorders is acute occult visual field loss resulting from receptor cell damage. Because the ophthalmoscopic fundus abnormalities are minimal except in MEWDS, the patients may easily be misdiagnosed as having pathological alterations of the central nervous system.

The ERGs are useful for the diagnosis; the full-field ERGs have different degrees of abnormalities depending on the extent of the visual field loss. In unilateral cases, the ERG of the

Azoor Syndrome
Fig. 3.20. Fundus of a patient with multiple evanescent white dot syndrome (MEWDS)

affected eye is always reduced compared to that of the normal fellow eye (Fig. 3.21). Above all, the most convincing diagnostic finding for these disorders is the approximate correspon dence of the subjective visual field defect to the low-amplitude zone in the multifocal ERGs (Fig. 3.22). The multifocal ERG findings indicate the retinal nature of the visual field loss.

Mewds And Erg
Fig. 3.21. Comparison of full-field ERGs for the eye with MEWDS and the normal fellow eye shown in Fig. 3.19. All ERG components are slightly smaller in the affected eye than in the normal fellow eye
Erg Multifocal

Fig. 3.22. Static visual fields (A) and topographic map of the amplitudes of the multifocal ERG responses (B) recorded from the patient with MEWDS shown in Fig. 3.20

Moreover and importantly, multifocal ERGs may be used to detect subclinical retinal dysfunction in these disorders.

The clinical course of acute idiopathic blind spot enlargement is exemplified by the case of a 35-year-old woman. This patient, in previous good health, noted a small purple flickering spot in the upper right field of her right eye. Her visual acuity was 1.0 in both eyes. Fundus examination and fluorescein angiography were normal, except for slight peripapillary hyperfluorescence (Fig. 3.23). Based on the blind spot enlargement of the static perimetry in her right eye, acute idiopathic blind spot enlargement was diagnosed. As shown in Fig. 3.24, abnormalities of the multifocal ERGs may remain in such patients even after the subjective static visual fields have recovered normal sensitivities at almost all locations [7].

Acute Retinal Syndrome

Fig. 3.23. Fundus photograph and fluorescein angiogra-phy of the right eye with acute idiopathic blind spot enlargement syndrome. (From Kondo et al. [4], with permission)

Azoor RetinaMultifocal Erg Azoor

Fig. 3.24. Results of static visual fields (A) and multifocal ERGs obtained from a patient with acute idiopathic blind spot enlargement syndrome shown in Fig. 3.23.These measurements were made 2 weeks (A-D) and 4 months (E-H) after the onset. The left-most panel is the gray scale of the static visual field thresholds.The second panel from the left shows the deviation plot of the static visual field.The third and fourth panels are the 61 response arrays and topographic map of the multifocal ERG responses. Note that the amplitudes of the ERG responses are reduced in a broad area in the temporal field where the visual fields have normal sensitivities at almost all locations. (From Kondo et al. [4], with permission)

Fig. 3.24. Results of static visual fields (A) and multifocal ERGs obtained from a patient with acute idiopathic blind spot enlargement syndrome shown in Fig. 3.23.These measurements were made 2 weeks (A-D) and 4 months (E-H) after the onset. The left-most panel is the gray scale of the static visual field thresholds.The second panel from the left shows the deviation plot of the static visual field.The third and fourth panels are the 61 response arrays and topographic map of the multifocal ERG responses. Note that the amplitudes of the ERG responses are reduced in a broad area in the temporal field where the visual fields have normal sensitivities at almost all locations. (From Kondo et al. [4], with permission)

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