Retinal Detachment refers to the process in which the inside lining of the eye, the retina, becomes separated from its normal position. This can happen as a consequence of numerous ocular diseases as well as a consequence of aging and/or trauma. When the retina is peeled away from its normal position, it undergoes a degenerative process whereby the cells have been peeled off and eventually deteriorate and die. Accordingly, there is visual loss and, in the long term, even though the retina may be put back into position, the chance for improvement of sight is quite marginal at this stage.
VARIATIONS OF DETACHMENT
The development of a retinal detachment is generally classified under the anatomical location of a detachment; if the macula is detached it means that the fovea is extended into the central macular area. Generally speaking, once the fovea has been detached, there is severe visual loss. Peripheral retinal detachments without macular detachments tend to be a less urgent cause for surgical intervention unless the retinal detachment is considered to be macular threatening.
CHRONIC RETINAL DETACHMENT
A chronic retinal detachment refers to the situation whereby a retinal detachment has been present for a very long period of time. This can be seen with certain critical signs including the presence of sub retinal fibrotic membranes or development of demarcation lines. In general, chronic retinal detachments must be repaired with surgical intervention including intraocular injections or even full surgical procedures in the operating room. In chronic retinal detachment, generally speaking, the chances for improvement of sight in the area that has been detached are quite marginal since the tissue has most likely undergone significant degenerative changes.
Following a retinal detachment in which the centre of the macula has been involved, this area of the retina can undergo further degenerative changes. In particular, a full thickness macular hole can develop following a retinal detachment surgery in which the retina becomes fully reattached. However, due to the macular hole formation there is marginal improvement of sight.
POST-DETACHMENT EPIRETINAL MEMBRANCE
Following a retinal detachment, there is liberation of sub retinal fibrotic cells into the vitreous cavity. These fibrotic cells can then layer out onto the surface of the retina leading to epiretinal membrane formations. One of the common locations for these cells to layer out is in the central macular area. Accordingly, one of the complications of a retinal detachment is in itself the development of an epiretinal membrane complex. This may require surgical intervention depending on the complexity of the epiretinal membrane and whether it is felt to be visually significant at this stage.
The development of proliferative vitreoretinal membranes (PVR), occur on the surface of the retina either in the pre-retinal or sub retinal space. PVR formation develops due to the retinal tear or break that is liberated inflammatory cells or fibrotic cells into the central vitreous cavity. These cells then undergo a transformation wherein they become fibrous tissues that bind to the retina and distort it, chronically reorganizing the retina. Accordingly, unless the PRV membranes are removed it is impossible to reattach the retina in many cases.
The development of subretinal membranes is one of the more complex challenges in vitreoretinal surgery. Some of these subretinal membranes can be exceedingly fine and delicate which make their removal easy. However, in certain situations, larger broad sheets of sub retinal fibrotic tissue may be found. In these patients, the chances for successful reattachment of the retina can be quite marginal and the risks of further PVR formation is quite high.
RETINAL TEAR/ HOLE TREATMENT
Since the majority of retinal detachments begin as small breaks or tears in the retina, early detection of these retinal holes or tears is essential in helping to prevent a full retinal detachment. Accordingly, laser treatments or Cryo treatments can be used to treat these peripheral areas of the retina as well as areas of vitreoretinal adhesion that are at high risk of progression into retinal detachments.
One of the common causes for retinal detachments is post-traumatic retinal detachment. This occurs when the eye is injured by severe trauma which can reflect inside of the eye leading to a retinal tear. These retinal tears seem to be larger than traditional smaller retinal tears as seen from the normal aging process. Once developed, a retinal tear will cause sub-retinal fluid to form which can lead to complete retinal detachment. Once the retina is detached, surgical intervention is warranted. Accordingly, reducing risk, including the use of visors and masks when playing sports, is essential. Thorough examinations by an eye care specialist are also important. Your retinal surgeon will be able to determine areas of vitreoretinal adhesion and tractional changes that may require surgical or laser therapy prior to retinal detachment formation.
Retinal Detachment, when chronically untreated, can result in permanent vision loss depending upon the size and location of the detachment. More specifically, large retinal detachments extending into the central macular region are higher risk for vision loss than small peripheral retinal detachments.
The successful reattachment of the retina is normally quoted as approximately 80%. These conservative numbers take into account the more complex cases that are performed by your Retinal Surgical team at the OCC Eyecare. Accordingly, since a large number of our surgical repairs are performed for complex vitreoretinal PVR diseases, it is still felt that the reasonable success rate from surgical intervention is approximately 80%. The limiting factors on this percentage include the risk of further PVR formations since surgery itself induces fibrotic tissue formation.
VISUAL ACUITY RECOVERY
Following retinal detachment in which the peripheral retina is detached, there can be a slow recovery of visual functioning in the peripheral retina. Conversely, when a detachment involves the central retina, responsible for the vision used in normal daily functions, there is a tendency towards limited improvement of sight, especially if the retina is detached is for more that twelve hours. Accordingly, the prognosis for visual recovery depends on several factors including:
1. Extent of the detachment pre-operatively
2. Time from retinal detachment involving macula to surgical intervention
3. Development of pre-retinal or sub-retinal membrane formations
4. Use of silicone oil or other intraocular medications post operatively
A scleral buckling procedure, in which the outer layer of the eye, or sclera, is indented inwards to bring it into approximation with a detached retina, remains one of the more basic surgical interventions offered to patients with retinal detachment. This complex surgical procedure involves the wrapping of a permanent piece of silicone on the outside lining of the eye. It is a surgical technique that requires many stages of intervention and very precise forms of localization of the retinal tears on the inside of the eye. This advanced surgical technique requires surgeons who have received training in vitreoretinal surgery.
A pneumatic retinopexy is the use of a gas bubble on the inside lining of the eye to help reattach the retina. This technique is now the preferred technique for retinal detachment repair amongst the surgeons at OCC. Those who have a successful repair with pneumatic retinopexy have a higher chance of visual recovery. The procedure involves an injection of C3F8 gas into the eye followed by appropriate head positioning. The head positioning is required to allow the bubble to float in certain directions depending on the position of the head relative to the retina tear or break that has led to the detachment. Freezing and laser treatments may accompany the pneumatic retinopexy to help to reattach and keep the retina in position.
Vitrectomy surgery, or removal of the vitreous contents from the inside lining of the eye, is considered to be one of the more advanced techniques available for retinal re-attachment surgeries. By approaching the detached retina from the inside of the eye, surgical tools and techniques can be used to re-attach the retina from the inside outwards. Unlike a scleral buckling procedure, which pushes the upward portion of the eye inward, a retinal detachment surgery with vitrectomy pushes the inner portion of the eye outwards towards the sclera. Once in position, using a variety of surgical techniques including heavy fluids or air to push the retina into position, laser or cryo treatments can be performed. Reattachment of the retina using vitrectomy surgery can approach anywhere from 80-97 % depending on the underlying cause of the retinal detachment and the presence of retinal scar tissue formation.
Silicone oil is a liquefied form of silicone that can be placed into the vitreous cavity following a vitrectomy surgery. Silicone oil is used in patients who have retinal detachments that are very complicated and are at high risk for subsequent detachments should oil not be used. The decision to use oil is a surgical decision and generally made at the time of surgery by your vitreoretinal surgical team. Silicone oil has complications associated with it which include cataract formation and glaucoma. There are steps taken to mitigate these risks at the time of surgery, including concurrent removal of any cataract. In patients who have silicone oil in their eye, the silicone oil can remain in position for up to ten years following surgery without the need for removal.
PVR formation or scar tissue formation on the pre-retinal or sub-retinal surface of a retina that has been detached is the most complicated development in patients with a retinal detachment. PVR formation is the reason most retinal detachment surgeries fail. The removal of PVR membranes at surgical intervention uses a combination of surgical instruments including scissors, retinal forceps, and picks to strip or remove these pre-retinal membranes. In many cases, the membranes are impossible to remove completely and segmentation (partial removal) may be necessary. Additionally, sub-retinal membranes can also be removed, but these require the formation of retinal holes for the surgeon to remove the membranes. This is a very complicated type of surgical intervention for PVR membranes and is only performed by highly trained retinal surgeons.