History of present illness
A 53-year-old female patient presented with a 3-month history of gradually worsening vision in both eyes, particularly affecting reading text. She denied metamorphopsia, floaters, or scotoma. Her past ocular history was unremarkable, though past medical history included type 2 diabetes mellitus (DM).
Ocular examination
Corrected visual acuity was 20/50 in each eye and improved to 20/40 in each eye with a low myopic manifest refraction. Intraocular pressures were normal, and anterior segment examination was unremarkable bilaterally. Dilated fundus examination demonstrated a blunted foveal reflex with subtle graying of the parafoveal region bilaterally, subtle hyperpigmentation temporal to the fovea on the right, and sparse punctate refractile foci parafoveally in both eyes, more pronounced on the left ( Fig. 20.1 ).
Imaging
Optical coherence tomography (OCT) showed foveal intraretinal cavitations in both eyes and bilateral loss of the ellipsoid zone (EZ) layer juxtafoveally, involving the fovea on the right. Alterations of the right fovea also included disruption of the interdigitation layer, subtle irregularity of the retinal pigment epithelium/Bruch membrane layer, and retinal thinning ( Fig. 20.2 ). Red-free (RF) photographs ( Fig. 20.3 ) and confocal blue light reflectance (CBR) imaging ( Fig. 20.4 ) highlighted the presence of crystalline deposits in the parafoveal regions bilaterally. Fluorescein angiography (FA) demonstrated right-angled venules temporal to the fovea with telangiectasis of juxtafoveal capillaries (more pronounced temporally) in early frames and leakage (temporally more than nasally) in late frames ( Fig. 20.5 ).
Questions to ask
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How long ago was DM diagnosed, has hyperglycemia been well controlled, and does the patient have other vascular disease? Diabetic macular edema (DME) or past retinal vein occlusion (RVO) can cause macular microvascular alterations with a variable degree of retinal thickening (macular edema [ME]).
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What medications has the patient used? Certain medications (e.g., niacin, latanoprost) can cause cystoid macula edema (CME). Others (e.g., tamoxifen) can cause intraretinal cavitations and/or refractile retinal deposits.
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Is there any family history of ocular diseases? Certain inherited diseases have been reported to demonstrate similar cavitations, including retinitis pigmentosa and cone dystrophies. Other inherited dystrophies can cause crystalline retinal deposits.
Assessment
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This is a case of a 53-year-old female patient with DM who manifests decreased visual acuity in both eyes, bilateral parafoveal graying with refractile foci, bilateral cavitations and EZ loss without retinal thickening on OCT, and parafoveal microvascular changes with leakage on FA in both eyes.
Differential diagnosis
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Branch or central RVO
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Diabetic retinopathy
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Cone dystrophy
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Pseudophakic CME (subclinical)
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Idiopathic macular telangiectasia (MacTel) (type II)
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Idiopathic MacTel (type III)
Working diagnosis
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Idiopathic MacTel type II
Multimodal testing and results
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Fundus photos
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Fundus examination classically shows graying of the parafoveal region, with refractile foci ( Fig. 20.1 ). Dilated capillaries may or may not be visible. With progression, pigmentary deposition may appear temporal to the fovea.
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Fundus autofluorescence
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Autofluorescence imaging often demonstrates mild to moderate hyperautofluorescence of the fovea and/or temporal parafovea in early MacTel, which can progress to a mixed hyper- and hypoautofluorescence pattern as pigment deposition and atrophy develop ( Fig. 20.6 ).
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