A Case of Posterior Vitreous Detachment – Medical Student Clinical Pearl
Ben McMullin, Clinical Clerk III
Dalhousie Medicine New Brunswick, Saint John
Reviewed by Dr. David Lewis
Copyedited by Dr. Mandy Peach
Case Presentation
A 61 year old female presented to the emergency department complaining of a floater in her right eye, which appeared 3 days prior to presentation. The floater moved with her eye movements. The patient claimed that her vision in the right eye was slightly blurry over the past 3 days but denied any significant decline in visual acuity. She denied any trauma, eye pain, discharge, or redness, but was particularly concerned since she was blind in her left eye since childhood.
On examination, the patients right eye appeared normal, with no discharge or conjunctival injection. Her pupil was roughly 3 mm and reactive to light. Her visual acuity was 20/30 in the right eye, and extraocular eye movements as well as visual field testing were normal. The intraocular pressure in her right eye was 9 mmHg.
Anatomy of the Eye
Figure 1: Normal eye anatomy as seen with ultrasound imaging.1
The cornea is the most superficial convex membrane, and immediately posterior to this is the anterior chamber, which is seen as anechoic on sonography. Posterior to the anterior chamber is the iris. Immediately posterior to the lens is the posterior chamber, which is also anechoic on sonography. The outer membrane of the eye from the inner most layer to the outer consists of the retina, choroid, and sclera.2
Differential Diagnosis for Non-Traumatic Visual Disturbance
• Posterior vitreous detachment
• Retinal tear
• Vitreous hemorrhage
• Vitreous inflammation
• Ocular lymphoma
• Intraocular foreign body
• Uveitis3
POCUS Ocular Exam
Advantages of POCUS
Ultrasound is a useful tool in the evaluation of some ocular complaints in the ED. Dilated fundoscopic examination is not always easily performed in the ED, but bedside ultrasound is becoming more readily available to physicians.4,5 Ultrasound can be useful in diagnosis of a wide range of ocular complaints, such as retinal detachment, posterior vitreous detachment (PVD), vitreous hemorrhage, and intraocular foreign body.4
Technique
Depending on the clinical history, a bedside ultrasound examination of the eye may be performed with the patient either supine or sitting in a chair.4 A high frequency probe should be used for this exam.1
Liberal amounts of gel should be used when performing a POCUS ocular exam, so as to minimize the amount of pressure placed on the eye.4 The gel does not need to be sterile, however for patient comfort, some physicians place tegaderm over the eye being examined. In order to orient the probe properly, ensure that the indicator on the probe is pointing towards the patients head when performing a longitudinal scan, and to the patients right when performing a transverse scan.1
To ensure that the entire eye is assessed, the eye should be examined in both the longitudinal and transverse planes, and it is important to sweep through in both directions. If the patient is able, it is also helpful to ask them to look to the right and left, as well as up and down with the probe on the eye.1 It is imperative to maximize brightness – if the field is too dark pathology like vitreous detachment can be easily missed.
PVD vs Retinal Detachment on POCUS
Complete retinal detachment will often appear as a V shape on ultrasound, with the apex seen at the optic nerve.5 Partial detachments can be more subtle and can appear differently from case to case.6
PVD is less echogenic than retinal detachment. PVD can often be seen moving with eye movements, more so than with retinal detachment.5 There is often a lag seen between movement of the globe, and movement of the vitreous appendage. In PVD, the detached vitreous is not connected to the optic disc, which contrasts with retinal detatchment.6 PVD can vary widely in size and can be seen with or without vitreous hemorrhage.2
Figure 2: Retinal detachment visualized on point of care ultrasound.6
Figure 3: Retinal detachment on ultrasound. (PoCUS Atlas)
Figure 4: Posterior vitreous detachment visualized on point of care ultrasound.2
Figure 5: Vitreous detachment on ultrasound (PoCUS Atlas).
Management
In the ED, retinal detachment requires urgent referral to ophthalmology. Retinal detachment can progress to total vision loss and should be seen and treated within 24 hours.3 In contrast, isolated PVD has a much better prognosis. Typically, floaters resolve within 3 to 12 months, but patients should still be referred for follow-up within 3 months to ensure no retinal tear is detected.3
Case Conclusion
Bedside ocular ultrasound showed PVD in the patient’s right eye, with no evidence of vitreous hemorrhage or retinal detachment. The patient was reassured of the prognosis but given that she was completely dependent on her right eye for vision, ophthalmology agreed to assess her the following week.
References
- Roque PJ, Hatch N, Barr L, Wu TS. Bedside Ocular Ultrasound. Crit Care Clin 2014; 30(2): 227-241.
- Southern, Simon. Ultrasound of the Eye. Australas J Ultrasound Med 2009; 12(1): 32-37.
- Arroyo, Jorge G. “Retinal detachment” last modified March 19, 2020, https://www.uptodate.com/contents/retinal-detachment?search=vitreous%20detachment§ionRank=1&usage_type=default&anchor=H3491968696&source=machineLearning&selectedTitle=1~11&display_rank=1#H1505785278.
- Lahham S, Qumber A, Bea MP, Lee C, Fox JC. Role of point of care ultrasound in the diagnosis of retinal detachment in the emergency department. Open Access Emergency Medicine 2019; 11: 265-270. Retrieved from https://search-proquest-com.ezproxy.library.dal.ca/docview/2314891088?accountid=%24%24CLIENTID&pq-origsite=primo.
- Botwin A, Engel A, Wasyliw C. The use of ocular ultrasound to diagnose retinal detachment: a case demonstrating sonographic findings. Emerg Radiol 2018; 25: 445-447.
- Gandhi K, Shyy W, Knight S, Teismann N. Point of care ultrasound for the evaluation of non traumatic visual disturbances in the emergency department: the VIGMO protocol. Am J Emerg Med 2019; 37 (8): 1547-1553.