Madtown Sono

Elderly male with vision loss

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By Daniel Wei, MD
Edited by Hani I. Kuttab, MD

Clinical Case

An elderly male presented to the emergency department with complaints of flashes of light in the upper lateral quadrant of his right eye. The flashes began suddenly a few hours ago. He endorsed a history of floaters in both eyes. He denied visual field loss and other associated symptoms. Vital signs were significant for a blood pressure of 177/100, heart rate of 71, and oxygen saturation of 97%. Physical exam revealed no evidence of trauma and no other focal neurological deficits. Bedside ocular ultrasound was performed (Figure 1 and 2).

Ocular ultrasound of the right eye (normal/high gain). This demonstrating floaters and no obvious detachments visualized.
Figure 1. Ocular ultrasound of the right eye (normal/high gain). This demonstrating floaters and no obvious detachments visualized.

Ocular ultrasound of the right eye (normal/high gain). This demonstrating floaters and no obvious detachments visualized.
Figure 2. Ocular ultrasound of the right eye (over-gained). This highlights a hyperechoic structure which traverses across the orbit.

Diagnosis

Posterior vitreous detachment. Bedside ultrasound revealed a faint, hyperechoic line concerning for a posterior vitreous detachment (PVD). Characteristics of PVD include a hyperechoic hyaloid membrane that is thin and mobile. The membrane is best visualized by over-gaining the ultrasound image and may be missed with low/normal gain. The main consideration for PVD is to differentiate it from retinal detachment (some patients may have both). Symptoms of PVD include increase in floaters or photopsias. Retinal detachments have similar presentation, but commonly are associated with other visual symptoms, such as a “curtain drawn over vision” or “straight lines appearing more curved”.

On ultrasound, retinal detachment involves a stiffer membrane with less dynamic movement on rotation of the eye. The retina is more hyperechoic than the posterior hyoid membrane and often does not require over-gaining for visualization. In retinal detachment, the membrane also remains attached to the optic nerve (Figure 3). Of note, in early PVD, the membrane may still be attached to the optic nerve. Thus, it is crucial to visualize the optic nerve on ultrasound exam and its relation to the possible detachments.

Schematic representation of retinal detachment, vitreous hemorrhage, and posterior vitreous detachment
Figure 3. Schematic representation of retinal detachment, vitreous hemorrhage, and posterior vitreous detachment (CoreEM.net)

Lastly, is also important to look for signs of vitreous hemorrhage. PVD typically has symptom resolution in several months; however posterior vitreous detachment with associated hemorrhage significantly increases the risk of subsequent retinal detachment (1-2). Ocular US has a sensitivity of 43% for PVD (likely lower since they can be easily missed without proper gain), 97% for retinal detachments, and 82-98% for vitreous hemorrhage (3-4).

Teaching point

Over-gaining your ultrasound image may reveal a posterior vitreous detachment you may not have otherwise visualized. Differentiate this condition from retinal detachment, which does not cross over the optic nerve. Search for associated vitreous hemorrhage, which significantly increases the risk of subsequent retinal detachment.

References

  1. Sharma S, Walker R, Brown GC, et al. “The importance of qualitative vitreous examination in patients with acute posterior vitreous detachment.” Archives of Ophthalmology 117.3 (1999): 343-346.
  2. Sarrafizadeh R, Hassan TS, Ruby AJ, et al. “Incidence of retinal detachment and visual outcome in eyes presenting with posterior vitreous separation and dense fundus-obscuring vitreous hemorrhage.” Ophthalmology 108.12 (2001): 2273-2278.
  3. Ojaghihaghighi S, Lombardi KM, Davis S, et al. Diagnosis of Traumatic Eye Injuries With Point-of-Care Ocular Ultrasonography in the Emergency Department. Ann Emerg Med. 2019 Sep;74(3):365-371.
  4. Lahham S, Shniter I, Thompson M, et al. “Point-of-care ultrasonography in the diagnosis of retinal detachment, vitreous hemorrhage, and vitreous detachment in the emergency department.” JAMA network open (2019): e192162-e192162.