Abstract
Purpose
To demonstrate the ability of widefield en face swept source optical coherence tomography (OCT) imaging to monitor peri-venular fern-like patterns of paracentral acute middle maculopathy (PAMM) associated with retinal arterial occlusions.
Observations
The peri-venular fern-like pattern of PAMM was diagnosed on the 12 × 12 mm en face structural OCT images from three patients. Fluorescein angiography images were unremarkable. Over time, all three patients demonstrated significant improvement in visual acuity with resolution of their peri-venular PAMM.
Conclusions
The peri-venular fern-like pattern of PAMM is usually associated with retinal vein occlusions, but we identified three cases with this pattern in eyes with presumed incomplete retinal arterial occlusions. Our cases support the ischemic cascade theory that begins within the deep capillary plexus and ascends in the retina depending on the severity of the ischemic event. Using the 12 × 12 mm en face structural OCT images, we are able to demonstrate a wider area of ischemia in PAMM compared with the traditional 6 × 6 mm scans.
1
Introduction
Paracentral acute middle maculopathy (PAMM) is a finding seen on optical coherence tomography (OCT) imaging that corresponds to ischemia in the deep and intermediate retinal capillary plexi. A hyperreflective band can be seen in the inner nuclear layer on OCT. PAMM can be associated with conditions such as diabetic retinopathy, hypertensive retinopathy, retinal arterial and vein occlusions, sickle cell retinopathy and other ischemic conditions. Fundus examination and fluorescein angiography (FA) findings may be unremarkable, but OCT imaging can reveal PAMM that suggests a serious underlying pathology and may warrant further investigation and systemic workup. While vision may not be significantly affected, patients may complain of a paracentral scotoma and visual distortions.
PAMM can be appreciated on en face OCT imaging by looking at a slab in the middle of the retina that includes the inner nuclear layer and the deep retinal capillaries. Three patterns of PAMM have been identified which include the peri-venular fern-like, arteriolar, and globular patterns. These patterns have been thought to reflect the spectrum of this disease, with the peri-venular fern-like pattern indicating milder disease and the globular pattern indicating more severe ischemia. The peri-venular fern-like pattern, which is characterized by lesions surrounding veins with peri-arterial sparing, has generally been associated with retinal vein occlusions. , Swept source OCT (SS OCT; PLEX Elite 9000, Carl Zeiss Meditec, Dublin, CA) can offer an advantage over traditional OCT imaging because of its wider field of view (FOV). We present three unique cases of peri-venular fern-like patterns of PAMM imaged using the 12 × 12 mm scan pattern obtained using SS-OCT.
2
Cases
2.1
Case 1
A 48-year-old Asian woman with a past medical history of hypertension presented with one day history of persistent blurry vision in the right eye. She had two previous episodes of transiently blurred vision in the right eye that resolved spontaneously. Visual acuity (VA) of the right eye was 20/70 + 1. Examination revealed retinal whitening along the superior arcade extending to the fovea ( Fig. 1 A), consistent with a superior branch retinal arterial occlusion (BRAO). En face structural OCT images of the middle retina from the 12 × 12 mm scan showed a peri-venular hyperreflectivity in a fern-like pattern ( Fig. 1 B) that corresponded to the retinal vascular map ( Fig. 1 C). Early and late FA images of the right eye did not reveal any areas of retinal nonperfusion ( Fig. 1 D). On closer examination of the macula using 6 × 6 mm en face structural images, the junctional zones between the presumed regions of perfused and ischemic retina could be easily identified ( Fig. 1 E) with the ischemic regions corresponding to areas of hyperreflectivity seen on the corresponding B-scan ( Fig. 1 F). The patient was admitted for a full cardiac workup. At one-month follow-up, there was improvement of the PAMM on en face structural OCT images and corresponding B-scans ( Fig. 4 A–C). Five months later, the BRAO had resolved with residual inner nuclear layer thinning and visual acuity in the right eye was 20/20.
2.2
Case 2
A 59-year old African-American man with a past medical history of hypertension, hyperlipidemia, and cerebrovascular accident presented with sudden onset blurry vision of the left eye. VA of the left eye was 20/60. Fundus examination revealed diffuse retinal whitening in the parafoveal region and along the vascular arcades consistent with a central retinal artery occlusion (CRAO ( Fig. 2 A)). En face structural OCT images of the middle retina from the 12 × 12 mm scan revealed a peri-venular pattern of PAMM around the retinal veins and sparing the retinal arteries ( Fig. 2 B–C). While FA did not show any transit delays or nonperfusion ( Fig. 2 D), the areas of ischemic and non-ischemic retina seen on the en face slab of the inner nuclear layer and the B-scan images were consistent with PAMM ( Fig. 2 E–F). At that visit, the patient was admitted for a stroke and cardiac workup. Over a two-month period, there was improvement in the peri-venular PAMM outside of the central macula ( Fig. 4 D–F). B-scans revealed thinning of the temporal foveal contour and retina ( Fig. 4 F). With time, retinal whitening on examination resolved with residual retinal thinning and the patient’s acuity stabilized at 20/40.
