Erik Massenzio B.A., Bradley Pittam MBChB, Benjamin Lin M.D., David Xu M.D.
In this article, we will be reviewing the essentials needed to understand and evaluate an acute retinal detachment, a disease process which may require urgent intervention. Since a retinal detachment sometimes requires urgent surgery, it is very important to be able to identify important elements of the history and exam, understand their significance, and communicate those findings.
What is a retinal detachment (RD)?
An RD is when the neurosensory retina detaches from the underlying retinal pigment epithelium (RPE). A key concept is that there is a potential space between these two structures. Much like other potential spaces in the body such as the peritoneal cavity or the pleural cavity, there are cellular mechanisms in place which ensure that any fluid that may collect in the subretinal space will be removed. In a retinal detachment, those mechanisms become overwhelmed, and the neurosensory retina becomes detached from the underlying RPE via fluid collection.
How to classify retinal detachments?
Retinal detachments are classified into three separate categories. While the same general principle of fluid accumulating in the subretinal space remains constant among these categories, the etiology of this fluid collection differs. In addition, we will go over retinal breaks and posterior vitreous detachments, which are two important precursors to retinal detachment.
A rhegmatogenous RD is the most common type, and is usually caused by a retinal tear, retinal hole, or other break. However, a break in the retina is not enough to cause detachment – there usually needs to be retinal traction and some liquefied vitreous. The traction on the retina allows the liquefied vitreous to enter the subretinal space, causing the neurosensory retina to detach and be starved from its underlying choroidal blood supply.
It is important to classify the type of retinal break since they may be treated with a different surgical procedure and/or be associated with a differing surgical prognosis. The types of retinal breaks include retinal tear, retinal hole, giant retinal tear, dialysis, and retinoschisis. Finally, recurrent rhegmatogenous RDs after failed surgical repair are often associated with proliferative vitreoretinopathy.
Adherent fibrovascular membranes are the cause of tractional RD. These fibrovascular membranes can be due to conditions such as proliferative diabetic retinopathy, retinopathy of prematurity, or penetrating posterior segment trauma. Any condition which causes scar tissue to form on the retina can cause a tractional detachment. These fibrovascular membranes contract over time and cause the retina to pull away from the RPE. In most tractional RDs, the detachment will develop slowly over time, as opposed to acutely in a rhegmatogenous detachment. However, tractional RDs can become combined with rhegmatogenous RDs if the traction leads to a tear or a hole.
The least common form of RD, exudative detachment, occurs when there is an accumulation of fluid without traction or retinal breaks. There are many causes of an exudative detachment, the most nefarious being an intraocular tumor. Other causes include iatrogenic (such as after panretinal photocoagulation), choroidal neovascularization, or uveitic/inflammatory causes such as Harada disease, posterior scleritis, or sympathetic ophthalmia. There are many other rarer causes of an exudative detachment. However, it is most important to know these broad categories. Keep the possibility of an ocular tumor in mind along with these other diagnoses.
Posterior Vitreous Detachment (PVD)
A PVD is not a retinal detachment, but it is an important risk factor for rhegmatogenous RDs. A PVD occurs when the vitreous gel liquefies and contracts with age. This contraction causes the posterior portion of the vitreous (also known as the posterior hyaloid membrane) to pull away from the neurosensory retina. This causes traction at the posterior aspect of the vitreous base where the vitreous inserts into the retina. Also, liquefied vitreous accumulates in the space between the now detached vitreous gel and the retina. Most of the time, a PVD occurs benignly, leading to annoying floaters for the patient. Occasionally, the attachment of the vitreous to the retina is so strong that a retinal tear occurs at the vitreous base. If this occurs, the liquefied vitreous can enter the defect, filling the potential space between the retina and the retinal pigment epithelium and cause an RD.
Retinal Tears and Holes
Retinal breaks are defined as any full thickness tears or holes in the retina. They are key risk factors for retinal detachments. Retinal tears are usually caused by traction on the retina from a PVD. Retinal holes are commonly caused by vitreous traction or lattice degeneration creating an atrophic hole.
Flashes of light (also known as “photopsias”) are a sign of irritation of the photoreceptor cells of the retina. These are most commonly from PVD but also occur in retinal tears and RDs.
Floaters are caused by opacities in the vitreous. They are commonly described as “spots” or “cobwebs”. Floaters are most commonly benign from PVDs or vitreous syneresis, but can also occur with RDs.
A visual field defect is the most concerning symptom. Patients usually describe these as a “dark shadow” or “curtain” progressively obscuring their vision. The location of this curtain-like visual field defect can be immensely useful in determining the location of the possible retinal detachment. The RD will most likely be in the opposite quadrant of where the curtain-like visual field disturbance originated.
It is important to remember that a patient may only present with mild symptoms, so any patient presenting with these symptoms should receive a careful dilated retinal exam.
After determining that the patient may be at risk for a retinal detachment, these are some of the exam findings that will be important to look for. It is important to perform indirect ophthalmoscopy with scleral depression in order to thoroughly examine the peripheral retina out to the ora for breaks or tears.
(Gauger et. al., 2014)
|Shafer sign (“tobacco dust”)|
This is pathognomonic for retinal breaks and detachments. Also known as “tobacco dust,” Shafer sign describes visualization of pigment granules in the anterior vitreous. These pigment granules come from the RPE. Retinal breaks allow leakage of RPE cells though the neurosensory retina into the anterior vitreous.
(Chin and Chan, 2013)
|Retinal breaks |
Retinal breaks appear as sharply demarcated, red colored openings in the retina. The reddish color comes from seeing the underlying RPE. The term
(UT Southwestern Medical School, Department of Ophthalmology)
|Vitreous hemorrhage |
Vitreous hemorrhages can occur when retinal breaks or PVD disrupt a blood vessel. Most vitreous hemorrhages are secondary to diabetic retinopathy, but should also prompt further examination to rule out a tear or retinal detachment.
(Wills Eye Hospital, Retina Service)
An RD can be visualized by appreciating the billowing sheet-like retina lifted off the RPE.
Sometimes vitreous hemorrhage or dense cataracts preclude a good retinal exam. In these instances, ultrasound can be invaluable. Look for a waving/flapping white line of tissue. It is important to distinguish a PVD from an RD on ultrasound.
A common retinal lesion predisposing to RD, lattice degeneration represents a weakening of the retina. This occurs in about 6-10% of the population. Although only ~1% of patients with lattice will progress to retinal detachment, about 20-30% of all eyes that present with rhegmatogenous RD will have lattice. Look for it temporally and superiorly. If this is found in an asymptomatic patient, it is important to warn the patient of the symptoms of RD.
Diagnosis and reporting
When a patient presents with symptoms concerning for PVD or RD, make sure to report these findings:
- Presence or absence of a detachment
- Whether the detachment is macula-on (“mac-on”) or macula off (“mac-off”)
- Where the primary break(s) are located
- Whether there is any difficulty visualizing the retina (vitreous hemorrhage or media opacity)
- Presence of a posterior vitreous detachment
- Lens status in affected eye (phakic or pseudophakic)
- Any lesions (especially lattice degeneration) in the fellow eye
Patients with “mac-on” retinal detachments require surgery urgently, while patients with “mac-off” detachments may be delayed a short time. This is because if it is “mac-on”, the macula can still be saved with quick intervention. However, if it is “mac-off”, surgical repair within several days will lead to the same visual outcome.
If the patient does not have an RD, perform a careful indirect ophthalmoscopic exam with scleral depression to ensure there are no retinal breaks present.
Treatments for retinal breaks
Laser retinopexy can be performed via slit lamp or indirect ophthalmoscopy. Applying photocoagulation around the retinal break creates scar tissue that prevents the retinal break from expanding. Laser retinopexy is usually preferred due to its accuracy over cryotherapy.
Cryoretinopexy, unlike laser retinopexy, usually requires subconjunctival or regional anesthesia. The cryotherapy probe is placed on the outside of the eye where the retinal break can be visualized with indirect ophthalmoscopy. Retinal break sealing is achieved through freezing and thawing of the affected tissue. Cryotherapy may be preferred when there is significant media opacity or for multiple or extensive breaks.
Treatments for retinal detachment
Vitrectomy with tamponade is the treatment of choice for more complex retinal detachments. As the name suggests, complete removal of the vitreous is achieved via a vitreous cutting tool inserted ~3.5 mm behind the limbus. Retinal breaks are sealed with laser or cryotherapy. Tamponading agents such as air, hexafluoride (SF6), perfluoropropane (C3F8), or silicone oil are used to plaster the detached retina back onto the RPE. If the patient is being treated for a tractional detachment, vitrectomy is almost always combined with panretinal photocoagulation in order to prevent neovascularization.
Pneumatic retinopexy consists of injecting an SF6 or C3F8 gas bubble in addition to sealing the retinal break with laser or cryotherapy. It has the advantage of being a quicker outpatient procedure; however, it is only indicated for smaller breaks and uncomplicated detachments. Pneumatic retinopexy can also only be used for superior breaks because the gas bubble floats upwards.
Scleral buckle is a silicone band that is placed around the eye and tightened around the eye like a belt. It may used in conjunction with cryotherapy or laser in order to facilitate the repair of breaks. Scleral buckle is often used in younger patients.
- Bowling, B. (2015). Kanski’s clinical ophthalmology: a systematic approach. Saunders Ltd
- Chin, E., Chan, C. (2013). Figure 8 [Image]. Retrieved from http://www.eyerounds.org/atlas/pages/retinal-breaks-w-PVR-gradeC.htm
- Gauger, E., Chin, E., Sohn, E. (2014). Shafer’s Sign [Image]. Retrieved from https://eyerounds.org/cases/196-PVD.htm
- Patel, Sayjal. “Retinal Detachment.” EyeWiki, 23 July 2019, eyewiki.aao.org/Retinal_Detachment.
- Sohn, EH. (2013). B-scan of an eye with retinal detachment [Image]. Retrieved from https://webeye.ophth.uiowa.edu/eyeforum/tutorials/retinal-detachment-med-students/index.htm
- Stone, Kevin. (2019). [Image]. Retrieved from https://www.backoftheeyemd.com/what-is-lattice-degeneration/
- UT Southwestern Medical School, Department of Ophthalmology. Vitreous hemorrhage [Image]. Retrieved from https://emedicine.medscape.com/article/799242-overview
- Wills Eye Hospital, Retina Service. Retinal Detachment [Image]. Retrieved from https://www.willseye.org/disease_condition/retinal-detachment/