The Ins and Outs of Retinal Detachments
The office phone rings as the clock strikes 5:00 pm on a Friday. What words do you most dread hearing from a patient? “I just noticed some flashes of light with a bunch of spots floating around in my vision.” It’s an optometric nightmare, right?
Wrong. Optometrists should be eager to advise this patient to come to the office immediately for a dilated retinal examination. Identifying a retinal detachment (RD) and sending this patient for an urgent referral provides you with an opportunity to help the patient maneuver through a potentially blinding condition.
TYPES OF RETINAL DETACHMENT
Let’s start with the basics. An RD occurs when the neurosensory retina is separated from the underlying retinal pigment epithelium (RPE). There are three categories we use to describe RDs: rhegmatogenous, tractional, and exudative.
Rhegmatogenous
This is the most common form of RD. The incidence of rhegmatogenous RD varies, but a common estimate is that it occurs in one in 10,000 people.1 A rhegmatogenous RD arises when a tear, or rhegma, exposes the subretinal area to the vitreous, vitreous fluid seeps underneath the tear, and lifts the neurosensory retina away from the RPE.
There are several causes for retinal tears, including trauma and myopia, but they are more commonly caused by posterior vitreous detachment (PVD).2,3
Tractional
This category of RD can be caused by a variety of conditions, including retinal vein occlusions and retinopathy of prematurity, but they usually occur in patients with diabetic eye disease. Advanced proliferative diabetic retinopathy exacerbates retinal ischemia. Ischemia leads to the release of growth factors such as VEGF. These growth factors induce angiogenesis, creating immature, fragile blood vessels. This neovascular network germinates toward the surface of the inner retina contiguous between the internal limiting membrane and the posterior hyaloid face. Concurrently, glial cells propagate and create fibrous tissue that combines with neovascular vessels to form a fibrovascular structure with the ability to contract and exert traction on the retina. These tractional forces may induce hemorrhaging and tractional RD.4
Interestingly, whereas PVD is a common cause of rhegmatogenous RD, PVD is protective against tractional RD. Removing the vitreoretinal interface eliminates the scaffold required for the fibrovascular growth that leads to tractional RD.
Exudative
Exudative RDs are the result of subretinal fluid accumulation secondary to the breakdown of the blood-retina barrier.4 The potential causes of exudative RD are many, including inflammatory conditions, such as uveitis and scleritis, neoplastic disorders, Coats disease, and more.5
SIGNS AND SYMPTOMS
The most commonly reported symptoms of RD are flashes of light, usually peripherally, and floaters, which often appear as spots or cobwebs.6 Additionally, VA can significantly decrease if the macula becomes detached.
Signs of an RD depend on the type of detachment. A thorough dilated retinal examination should be performed to investigate for retinal breaks or tears and for subretinal fluid. Binocular indirect ophthalmoscopy or an examination at the slit lamp with a condensing lens is usually sufficient to evaluate the peripheral retina. A three-mirror gonioscopy lens or scleral depression may be needed to visualize peripheral lesions near the ora serrata.
Auxiliary testing to diagnose RD may include OCT and widefield retinal imaging. Don’t forget to look carefully for Shafer sign, also known as tobacco dust—pigment cells in the anterior vitreous caused by disruption of the RPE. Shafer sign is virtually pathognomonic for a retinal break.
WHO IS AT HIGH RISK?
Risk factors for RD include, but are not limited to, myopia (especially high myopia), cataract surgery, trauma, a family history of RD, and an RD in the other eye.7
It is important for patients at heightened risk for RD to have annual dilated retinal examinations to appropriately assess their retinal health. Additionally, eye care providers must educate these high-risk patients regarding the possible symptoms of RDs enumerated above.
TREATMENT
Treatment of RD varies depending on the type of RD, the location and number of retinal breaks or tears, lens status, and other factors. It is paramount to determine whether the macula is attached or not; A macula-on RD will usually be treated sooner than a macula-off RD. Waiting too long to repair an RD with macular involvement may lead to a significant reduction in the patient’s vision.8
Pneumatic retinopexy, scleral buckling, vitrectomy, or any combination of the three, are the main surgical choices for RD repair. Exudative RDs are the exception. In these cases, treatment is aimed at addressing the underlying disease. See Treatment Options for RDs for details on the surgical options for repairing RDs.
TREATMENT OPTIONS FOR RDs
(http://bit.ly/0919MOD) PneumaticPneumatic retinopexy combines application of cryopexy or laser retinopexy to the area of detached retina with gas bubble injection to tamponade the RD.
(http://bit.ly/0919MODScleralBuckle)) A silicone or plastic band is placed on the outside of the globe to indent the area of the eye with the detached retina. This alleviates pressure on the retinal break, allowing the tear to reattach to the wall of the eye.
(http://bit.ly/0919MOD) VitrectomyThe vitreous gel is removed and replaced with a bubble (eg, gas, silicone, air). Separating the posterior hyaloid from the retina relieves vitreoretinal tractional forces to facilitate RD repair.
PUT YOUR TRAINING TO GOOD USE
Identifying retinal detachments requires skill and a careful eye. Understanding key signs of RD that can be identified during a retinal examination, and educating your high-risk patients on the symptoms of RD, can increase your chances of successful diagnosis.
Urgent referral is often necessary to optimize visual prognosis. Surgical repair is left to the discretion of the retina specialist, but having a grasp of the treatment options will aid you in educating your patients and establishing yourself as an optometrist with expertise in retinal pathology.
Don’t grumble over the add-on RD patient on a Friday evening. Make use of your training, practice medical optometry, and help your patients.
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