“Give me a break…said no retina ever!” – Someone very wise
As we know, the retina is the light-sensitive layer of the eye responsible for vision. It is like a sheath or a thin blanket which is normally attached to the underlying retinal pigment epithelium (RPE) and choroidal layer. The direct apposition of the retina to the RPE is essential for normal retinal function. Whenever there is a break in this sheath-like membrane, fluid gets accumulated beneath and leads to a condition called retinal detachment.
Retinal detachment can be defined as the separation of the neurosensory retina from the underlying RPE. The main cause of a Rhegmatogenous Retinal Detachment (RRD) is a retinal ‘break’ or ‘hole’ which refers to a full thickness defect in the retina. A retinal ‘break’ allows the inward movement of fluid from the vitreous cavity to the space under the retina (sub-retinal space), resulting in retinal separation. Total RRD means complete detachment of the retina, while subtotal detachment means a part of the retina is detached. When the retina is detached, the amount of blood supply reaching it is minimal, as a result of which ischemia (death of tissue due to lack of blood supply) could set in over a period of time. The longer it remains detached, more the chances of ischemia and poorer the recovery post treatment. An important factor that governs vision is whether the macula is attached or detached. If the macula is attached, the chances of vision gain are more as compared to when the macula is detached.
There are various risk factors for RRD. These include –
- High myopia- A spectacle correction of up to -3D increases the risk of RRD by 4 times than in normal individuals. Myopia also causes vitreous degeneration to occur faster which also increases the risk for RRD. A regular yearly check-up of myopic patients is therefore necessary. For patients undergoing refractive surgery for myopia, a retinal evaluation is a must pre-op and if there is a suspected lesion, it should be tackled with laser photocoagulation.
- Trauma- The sudden movement of the vitreous in blunt ocular trauma may lead to a sudden pull on the peripheral retina leading to an extensive tearing of the retina around the base of the vitreous. It can commonly lead to a giant retinal tear or retinal dialysis.
- Intraocular Surgery- Any intraocular surgery like cataract surgery hastens liquefaction of the vitreous humor. If there is a break anywhere in the retina, it can lead to RRD. The risk of detachment is sevenfold after six years after cataract surgery, and the danger grows as the postoperative time increases. The minimal risk of retinal detachment should be explained to cataract patients before operation, but it is definitely not a reason for canceling surgery that is indicated.
- Retinal degenerative lesion- Lattice degeneration is the most common degeneration predisposing to RRD. It is seen in 6-8% of people in the general population. Although lattice degeneration is a risk factor for RRD, the large majority of patients with lattice lesions do not develop RRD unless there are no additional holes or tears. Other peripheral
retinal abnormalities such as snail track degeneration (a variant of lattice degeneration) and cystic retinal tufts commonly have focal areas of abnormal vitreoretinal adhesion and may predispose to retinal tears and detachment. Hence, a routine retinal evaluation is
a must in people having these lesions.
- Laser capsulotomy- Post cataract surgery, sometimes there is opacification in the lens for which laser capsulotomy is performed. Direct damage to the retina or vitreous changes like posterior vitreous detachment secondary to the capsulotomy can occur which might
lead to RRD.
- History of Chorioretinitis- Chorioretinitis and uveitis cause liquefaction of the vitreous gel and cause the formation of epiretinal membranes. These changes tend to precipitate retinal detachment.
- RRD in the other eye/ family history- If an RRD has occurred in one eye of a person who has an asymptomatic retinal lesion in the second eye, the chances of retinal detachment in the other eye appear to be higher. Hence such lesions should be lasered before long. Also, it is said to have a minor genetic predisposition, hence this aspect should be noted while taking history.
Most patients report abnormal phenomena like ‘floaters’ and ‘flashes of light” (photopsia) which are seen before the actual detachment. Floaters are seen due to vitreous opacities and they are mobile and can be seen as floating black opacities that move with the movement of
the eyeball. It is seen due to incomplete liquefaction of vitreous. They can be seen as cobwebs or threads floating in front of the eye. Photopsias are flashes of lights seen due to incomplete detachment of the posterior vitreous. This incomplete detachment causes a pull on the retina at the
places where it is attached which may stimulate the retina hence causing the visualization of light. If the retina then becomes detached, the patient perceives a light to dark gray shadow; in a few cases, the shadow is completely black. As opposed to floaters, this shadow does not move
when the direction of gaze changes. It feels as if a curtain has been drawn over the part of the eye where the detachment has occurred. If this detachment involves the macular, a significant loss of vision can occur immediately. Sometimes, due to the retinal detachment, there can be a tear in one of the blood vessels leading to vitreous hemorrhage which obscures the vision even more.
Anterior Segment examination might reveal some flare and cells in the Anterior Chamber. There may be a Relative Afferent Pupillary Defect (RAPD) if the area of involvement is large. Light reflex on Retinoscopy may be gray instead of the normal orange reflex. The patient may have a
visual field defect corresponding to the detached retina which may help guide the ophthalmologist to look for the detachment. Examination of the entire fundus with Binocular Indirect Ophthalmoscope (BIO) is necessary to document the detached retina and the possible causes like breaks or holes and their numbers which will have to be sealed while undergoing surgery. On BIO, an acute detachment looks like an elevated retina with loss of transparency due to which structures under the retina are not visible, the margin of the detached and attached retina share a white line. An old RD looks atrophic, with a pigmented demarcation line between the detached and attached retina, with increased opacification and thickened retinal folds known as Proliferative VitreoRetinopathy (PVR), intraretinal cysts maybe are seen as well. The Intra Ocular Pressure (IOP) may be low or high. Low IOP may be due to increased outflow of intraocular fluid through subretinal space. The IOP may be high in old RDs due to anterior migration of degenerated photoreceptor cell or RPE pigments which block the normal trabecular outflow. This is known as Schwartz-Matsuo syndrome.
B scan- This is an ultrasonography of the eye which can be used to assess the status of vitreous cavity and retina, choroid or sclera when it cannot be viewed directly under BIO. B scan can be used to determine the presence or absence or RD, its location, macular involvement, how old the RD is, presence of PVD. On B scan, RRD appears as a free floating membrane in the vitreous cavity with high reflectivity on A scan having an attachment at the disc.
Preventive measures can be taken for patients having conditions like Myopia, peripheral retinal Degeneration or various syndromes. In these patients, routine examination may reveal the presence of a tear or a hole in the peripheral retina. These breaks, holes and lattice degeneration are usually treated with transconjunctival cryotherapy or laser photocoagulation. In cryotherapy, a probe shaped like a pen whose tip is cooled to very low temperatures is applied on the conjunctiva to freeze the retina through the outer layers of the eyeball. In laser photocoagulation, a high-energy beam is delivered through the ocular media to the affected area. Both these techniques cause an adhesion between the neurosensory retina and the Retinal Pigment Epithelium thus preventing fluid from entering into the potential space and causing RD. Cryo is relatively a painful procedure as compared to laser so is done under local anesthesia.
SURGICAL MANAGEMENT:- The main aim of surgical intervention is to reattach the retina to the RPE and to close all the breaks found in the retina to prevent further chances of RD. This can be done by applying pressure externally or internally to keep the retina attached to the RPE along with laser or cryotherapy of the margins of the breaks. These techniques include –
- Scleral Buckling- This technique uses external tamponade to achieve a functional closure of the retinal break with permanent retinal attachment by scleral indentation and coagulation of retinal holes. The goal is to create an inward indentation of the eye wall, thus approximating the retinal pigment epithelium to the neuroretina surrounding the break. Scleral indentation is achieved by the placement of a buckle at a location corresponding to the retinal break. The buckle is permanently anchored to the sclera with non-dissolvable sutures. Buckle materials include silicone sponge and hard silicone that come in a variety of shapes and sizes. The exact type of buckle required varies according to the desired buckle (scleral indentation) height, and location and number of breaks, and is to be decided by the operating surgeon.
- Pneumatic Retinopexy- In this technique, the retinal breaks/holes are sealed and a gas bubble is injected into the vitreous cavity to provide an internal tamponade against the retina. This technique is least invasive but also has a lower success rate as compared to the other procedures and so the patient would have a higher chance of re-detachment.
- Vitrectomy- This is the latest technique, which involves removal of vitreous (jelly inside the eye) which is causing traction on the retinal surface along with internal tamponade using various agents like gas or silicone oil along with sealing of all breaks/holes with laser/cryo. The gases/silicone oil replaces the vitreous and help in keeping the retinal adhered to the underlying RPE. Along with this, they also help in maintaining the shape and structure of the eyeball after removal of the vitreous. The common gases that can be used are air, perflouropropane (C3F8), hexafluoride (SF6). Gases get absorbed over a period of time, while silicone oil needs to be removed later on via a small procedure.
POST OP CARE AND PRECAUTIONS:-
The common post operative care that the patients have to take include taking your medications as instructed by your doctor is to take adequate rest, to not rub or press your eye and if instructed, wear protective glasses and an eye patch for when you sleep. Post operatively, there may be some redness and discomfort initially for the first week but this all is expected and is managed appropriately by medications. The patient may need to rest or sleep with their head in a certain position (head down/lateral). It is important that they follow what their doctor told them about head positions as it will help their eye recover from the surgery faster. It is important to ask about number of days of avoidance of air travel if the doctor has placed gas inside the eye. Avoiding strenuous activities is always better for three weeks at least post surgery.
COMPLICATIONS:- One of the common complications includes raised Intraocular Pressure (IOP). This is seen in almost 50% of patients and gives a feeling of discomfort, nausea, vomiting and ocular pain to the patient. This rise in pressure may be temporary and can be managed medically. Another complication that can be seen is Cataract development in phakic patients. Patient can have a gradual fall in vision due to the cataract and may require a surgery for removal of the same after a few months. Once the new intraocular lens is placed, the vision lost due to cataract can be regained. Retinal re-detachment is also a complication that can happen in a few number of cases. A sudden drop in vision post operatively should warrant you to visit your doctor immediately. The most dreaded complication is infection of the eye known as Endophthalmitis. If you feel that the pain or redness increases and there is a drop in vision along with discharge from the eye, you should visit your doctor immediately.
Sudden decrease of vision in one eye is an alarming condition for the patient. Early visit to the doctor not only helps them to understand what happened inside the eye but also increases the chances of gaining back good vision. The diagnosis of retinal detachment and a need for retinal surgery may seem too overwhelming initially but early surgery will lead to a better improvement in vision. Regular follow up by the patient is necessary for the doctor to assess the progress of the condition. Post operatively, the vision improves gradually as the retina takes time to function again. Different surgeries have a different recovery time but on an average it takes about 2 to 6 weeks. So the patient should not be alarmed if the vision does not improve drastically and immediately after the surgery.
In conclusion, Rhegmatogenous Retinal Detachment is an emergency condition but with swift and early management it can be treated and visual loss can be recovered. This requires awareness and alertness not just among doctors but also patients who need to know when to seek medical help. The goal is to identify and treat all the breaks and detachments and restore the vision as much as possible. This requires an equal effort from the doctor as well as the patient.