Flashes and floaters

05/11/2024

Flashes and Floaters : PVD vs Retinal Detachment

Author: Dr James Ng (10 minutes read)

Posterior vitreous detachment (PVD) and retinal detachment (RD) are two distinct but related ocular conditions that involve the separation of the vitreous gel from the retina. PVD is a common age-related process, whereas retinal detachment is a more serious and sight-threatening condition that requires urgent medical attention. While PVD can predispose individuals to retinal detachment, the two conditions differ in their underlying mechanisms, severity, and treatment approaches. Understanding their characteristics, diagnostic techniques, and management strategies is essential for preserving vision and preventing complications. This is especially important in a situation where we see an older demographics of patient.

Posterior Vitreous Detachment (PVD):

Definition: PVD occurs when the vitreous gel, which fills the eye, detaches from the retina, typically starting from the posterior pole. It is a normal part of aging but can also be associated with trauma, myopia, or other retinal conditions.

Symptoms: The primary symptoms of PVD are due to the vitreous separation from the retina:

  1. Floaters: Small spots or cobweb-like shapes that float in the field of vision, often more noticeable in bright light or while looking at a plain background.

  2. Flashes of light (photopsia): Brief bursts of light, especially in the peripheral vision, as the vitreous gel pulls on the retina.

  3. Blurred vision: This may occur in some cases but is less common than floaters or flashes.

  4. Sensation of a curtain or shadow: Although not typical of PVD alone, this symptom can indicate progression to retinal detachment.

Examination Findings:

  1. Vitreous changes: On slit-lamp examination, a PVD can be identified by the separation of the vitreous from the retina, with the posterior hyaloid membrane visible.

  2. Weiss ring: A characteristic sign of PVD, the Weiss ring appears as a large floater in the center of the vision, often indicating the point of vitreous attachment to the retina. (Tip: it is important to move your lens around and focus near the optic disc to identify and locate Weiss ring)

  3. Vitreoretinal traction: If there is residual vitreous traction on the retina, this may predispose to retinal tears or detachment.

Investigations:

  1. Ophthalmoscopy: A detailed examination of the retina with a direct or indirect ophthalmoscope helps identify any signs of retinal tears or other abnormalities associated with PVD. (In the eye clinic this is usually done with the slit lamp + 90 dioptre lens; when the indirect ophthalmoscope is used normally a 20 dioptre lens is used).

  2. Optical coherence tomography (OCT): OCT imaging may show the separation of the vitreous from the retina and assess the condition of the macula.

  3. Ultrasound B-scan: In cases of media opacity (e.g., cataract or hemorrhage), an ultrasound B-scan can help visualize the posterior segment and detect any retinal tears or detachment. (This is a useful way to differentiate PVD and RD when the media is hazy)

Treatment: In most cases, PVD is a self-limiting condition that resolves without the need for medical intervention. However, if symptoms such as flashes or floaters persist or worsen, or if there is concern for retinal tear or detachment, additional management may be necessary.

  1. Observation: Most cases of PVD resolve without intervention. Regular follow-up visits are essential to monitor for any complications such as retinal tears. Safety netting patients for red flags signs and symptoms of RD.

  2. Laser photocoagulation or cryotherapy: If retinal tears are detected, these treatments may be used to seal the tears and prevent progression to retinal detachment.

  3. Vitrectomy: In rare cases, if there is persistent vitreoretinal traction or other complications, surgical intervention in the form of vitrectomy (removal of the vitreous) may be considered.

Complications:

  1. Retinal tears: PVD can lead to retinal tears as the vitreous pulls on the retina. These tears can predispose to retinal detachment.

  2. Macular edema: Tractional forces from the vitreous may cause fluid accumulation in the macula, leading to vision problems.

  3. Retinal detachment: If left untreated, retinal tears caused by PVD can progress to retinal detachment, a sight-threatening condition.

Retinal Detachment (RD):

Retinal detachment occurs when the retina becomes separated from the underlying retinal pigment epithelium, resulting in disruption of visual function. It is a medical emergency that can lead to permanent vision loss if not treated promptly. Important risk factors to consider include myopia, trauma, infection, previous PVD/RD, previous eye surgery.

Types of Retinal Detachment:

  1. Rhegmatogenous retinal detachment: The most common type, caused by a retinal tear or hole, often associated with PVD. The vitreous gel leaks fluid into the subretinal space, causing the retina to detach.

  2. Tractional retinal detachment: Caused by scar tissue or abnormal growths that pull the retina away from the underlying tissue, often associated with diabetic retinopathy.

  3. Exudative retinal detachment: Occurs when fluid accumulates beneath the retina due to conditions such as inflammation, tumors, or vascular abnormalities, without a tear or hole in the retina.

Symptoms:

  1. Sudden vision loss: A partial or complete loss of vision in one eye, often described as a shadow or curtain descending across the field of vision.

  2. Floaters and flashes: Similar to PVD, but more pronounced and often associated with the progression of a retinal tear.

  3. Distorted vision: Straight lines may appear bent or distorted, indicating potential macular involvement.

  4. Peripheral vision loss: Patients often notice a loss of vision in the periphery, as the detachment may begin in the outer retina.

Examination Findings:

  1. Retinal tear or hole: On fundus examination, the detached retina may show visible tears or holes, often accompanied by subretinal fluid.

  2. Macular changes: In cases of macular detachment, the central vision may be significantly impacted.

  3. Tented retina: In severe cases, the retina may appear to be lifted or tented, with fluid accumulation beneath it.

  4. Schaffer's sign: Presence of pigment in the vitreous cavity, which indicates retinal break and the potential for retinal detachment. (Tip: this is best seen when focusing the slit lamp on the vitreous by moving the focus closer to the eye compared to when doing an anterior segment examination).

Investigations:

  1. Ophthalmoscopy: Fundus examination is critical for identifying retinal tears, breaks, and the extent of detachment. Again this could be done with slit lamp or indirect ophthalmoscope.

  2. B-scan ultrasound: Used when the view of the retina is obscured by cataract or vitreous hemorrhage, this imaging helps visualize the detached retina.

  3. Optical coherence tomography (OCT): Useful in assessing the retinal layers and detecting subretinal fluid accumulation.

Treatment: Retinal detachment is a medical emergency that requires immediate intervention to prevent permanent vision loss. Treatment depends on the type, location, and severity of the detachment.

  1. Laser photocoagulation or cryotherapy: Used to treat small retinal tears or holes by creating a scar around the tear to seal it and prevent further detachment.

  2. Pneumatic retinopexy: Involves injecting a gas bubble into the vitreous cavity to push the retina back into place, followed by laser treatment or cryotherapy to seal the retinal tear.

  3. Scleral buckling: A surgical procedure that involves placing a silicone band around the eye to push the wall of the eye inward and reattach the retina. Laser or cryotherapy is then used to seal the retinal tear.

  4. Vitrectomy: In cases of severe or complicated retinal detachment, a vitrectomy may be performed to remove the vitreous gel and replace it with a gas or silicone oil to help reattach the retina.

Complications:

  1. Vision loss: If the detachment involves the macula or if treatment is delayed, significant vision loss can occur.

  2. Cataract formation: Cataracts can develop following retinal detachment surgery, especially after vitrectomy.

  3. Infection (endophthalmitis): Post-surgical infection is a risk following any retinal detachment surgery.

  4. Re-detachment: In some cases, the retina may re-detach, requiring further surgical intervention.

Conclusion: Both posterior vitreous detachment and retinal detachment are critical ocular conditions that require prompt diagnosis and intervention. While PVD is often a benign, age-related occurrence, it can lead to retinal tears and detachment, making early detection essential. Retinal detachment is a sight-threatening emergency, and timely surgical treatment is crucial for restoring vision and preventing permanent blindness. Regular eye exams and immediate consultation with an ophthalmologist are vital for anyone experiencing symptoms of vitreous or retinal detachment.

References:

  1. Ryan, S. J., & Schachat, A. P. (2017). Retina (5th ed.). Elsevier.

  2. Wilkinson, C. P., & Olk, R. J. (2000). Retinal detachment and vitreous surgery. American Journal of Ophthalmology, 130(6), 739-742.

  3. Gass, J. D. M. (1988). Surgical management of retinal detachment. Mosby Year Book.

  4. Margo, C. E., & Lahey, J. (1995). Retinal tears and detachment. Ophthalmology Clinics of North America, 8(2), 241-256.

  5. Dandona, L., & Dandona, R. (2006). Retinal detachment: Treatment options and prognosis. British Journal of Ophthalmology, 90(7), 831-837.


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