Optometry case study: Paracentral acute middle maculopathy

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Figure 3b. Red-free retinal photography of the RE showing a subtle wedge-like greyish lesion (arrow)

By Bernard Sakran, Specsavers Elanora, QLD

History

Px: 47-year-old male
Reason for visit: Had noticed 2 ‘grey small spots’ in RE vision which started 3 days prior to presentation. Reported experiencing some levels of stress recently.
GH: Medicated for hypertension, but otherwise generally healthy
POH: No ocular issues, SV since 2014 for distance, mild astigmatic myopia
FOH: No relevant issues

Clinical Assessment

Anterior segments: Normal
Pupils: Normal
BCVA: RE: 6/6      LE: 6/6
Refraction: RE: -0.50/-0.50×80      LE: -0.75/-1.00×85 ADD 1.25

Amsler grid: Pointed out two small paracentral dot scotomas superior temporal and inferior temporal to fixation in the affected RE (Figure 1)

Figure 1. Amsler grid of the RE as marked by the patient

Visual fields: RE visual field showed two paracentral scotomas, consistent with the chief complaint and the amsler grid results (Figure 2). LE normal.

Figure 2. Visual field test of the RE showing paracentral areas of reduced sensitivity

Fundus examination: Ophthalmoscopic examination of the RE revealed no obvious disease and almost a normal foveal reflex (Figure 3a). However, the red-free image (Figure 3b) and closer inspection showed a subtle lesion adjacent to the macula (Figure 3c). LE normal.

Diagnosis & Management

Differential diagnosis:

  • Central serous retinopathy (CSR)
  • Diabetic macular oedema (DMO)
  • Idiopathic choroidal neovascular membrane
  • Paracentral acute middle maculopathy
  • Acute macular neuroretinopathy
  • Acute retinal pigment epitheliitis (Krill’s disease)
  • Multiple evanescent white dot syndrome
  • Acute posterior multifocal placoid pigment epitheliopathy
  • Old inner retinal infarcts

Diagnosis: Paracentral acute middle maculopathy

Management: Given the specific nature and onset of the scotomas, an ophthalmic referral was arranged for OCT and further investigation. Subsequently, the OCT results from the ophthalmologist showed a ‘plaque-like’ lesion (see Figures 4a and 4b), which is indicative of paracentral acute middle maculopathy (PAMM). The lesion corresponded to the scotomas. OCT of both optic nerves were normal.

There is currently no treatment for PAMM. Management is targeted toward the identification and treatment of related vascular, ocular and systemic risk factors. Therefore, the patient was referred for cardiovascular and carotid disease risk assessment. He was found to have uncontrolled blood pressure with elevated cholesterol levels.

Outcome: After two weeks’ tight management of his risk factors, the patient reported his scotomas remained stable although less noticeable. There was still no sign of inflammation and, clinically, the retinal lesion had faded.

After three months, there was only mild improvement in the lesion, although subjectively, the patient reported reduced awareness of the ‘grey spots’.

Discussion

PAMM lesions occur due to thinning and atrophy of the affected inner nuclear layer (INL). Although it is not as common as CSR or DMO, it is important to consider it as a differential, specifically with middle-aged patients.

It is now recognised that PAMM may manifest as a complication of various retinal vascular diseases, including diabetic retinopathy, hypertensive retinopathy, sickle cell retinopathy, Purtscher retinopathy, central retinal vein occlusion, and retinal artery occlusion.1 PAMM has also been observed in association with both carotid dissection and giant cell arteritis.2

Therefore, in the setting of PAMM with an apparently healthy fundus, the optometrist’s priority is to rule out central or branch retinal artery occlusions, followed up by a systemic work-up to rule out underlying carotid disease or giant cell arteritis.

It is also worth noting the hyperreflective OCT plaques resolve with subsequent atrophy of the INL, resulting in persistent long-term paracentral scotomas in affected patients.3


REFERENCES

  1. Chen X, Rahimy E, Sergott RC, et al. Spectrum of retinal vascular diseases associated with paracentral acute middle maculopathy. Am J Ophthalmol 2015;160:26–34.
  2. Yu S, Pang CE, Gong Y, et al. The spectrum of superficial and deep capillary ischemia in retinal artery occlusion. Am J Ophthalmol 2015;159:53–63.
  3. Sarraf D, Rahimy E, Fawzi AA, et Paracentral acute middle maculopathy. JAMA Ophthalmol 2013;131:1275.
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