Eye Care
The retina, which lines the inside of the posterior wall of the eye, may occasionally become detached for various reasons. Most commonly, retinal detachment occurs as a result of a tear or hole in the retina, which develops as a result of a posterior vitreous separation (PVS). The retinal tear or hole allows fluid to enter the subretinal space, thus detaching the retina.
The retina receives oxygen and nutrients from the underlying choroid (vascular layer) of the eye. When a retinal detachment occurs, the detached retina begins to dysfunction, and ultimately, necrosis (death) ensues as a result if the retina is not reattached to the underlying choroid. As such, a retinal detachment is an urgent condition. The detached retina should be recognized and treated promptly.
The surgical management of retinal detachment may include several different procedures, depending on the circumstances. These procedures include pneumatic retinopexy, scleral buckling, and vitrectomy.
Pneumatic Retinopexy
Pneumatic retinopexy is a procedure in which a gas bubble is placed inside the vitreous cavity, either before or after, the retinal hole is treated with laser or cryotherapy (freezing) to help seal the hole permanently. The gas bubble, which must be positioned over the hole, prevents fluid from entering the hole while the retina heals. Ophthalmologists sometimes use the phrase, "put the bubble on the trouble" to describe this aspect of the procedure to patients. Since the positioning of the bubble is dependent on positioning of the patient, pneumatic retinopexy is usually only appropriate for retinal detachments (with holes) in the superior (top) part of the eye.
Scleral Buckling
Scleral buckling surgery is probably the most commonly required procedure for repair of retinal detachment. In this procedure, a soft silicone band is placed around the eye, which indents the outside of the eye towards the detached retina, thereby relieving vitreous traction on the retinal hole. The buckle is much like a belt around one's waist. It is kept in place with tiny sutures to the sclera of the eye. In many cases, the vitreo-retinal surgeon drains the fluid under the retina at the site of the retinal detachment, and then seals the hole (or holes) with laser or cryotherapy.
Vitrectomy
In some cases, a vitrectomy is also necessary for repair of a retinal detachment. In this procedure, the vitreous humor is removed from the eye with an instrument known as a vitrector. This instrument utilizes a tiny guillotine cutting device to safely remove the vitreous while replacing it with saline.
Laser photocoagulation or cryotherapy are still typically used if a retinal hole or tear is present. A scleral buckling procedure may also be combined with the vitrectomy for certain types of retinal detachment.
After Reattachment
Following retinal reattachment surgery, you will likely be required to use antibiotic and anti-inflammatory eye drop medications, perhaps for a few weeks or more following surgery.
Recovery following retinal detachment repair will depend largely on the location and extent of retinal detachment prior to repair. The final visual result may not be known for up to several months following surgery. Your surgeon will be the best judge of what individual results you should expect.
Laser surgery has been used extensively for a lot of retinal disorders. The laser is usually attached to a slitlamp. With the patient’s head mounted on the slitlamp, the laser beam is applied through a contact lens into the patient’s eye. This is usually done under topical anesthesia. Other laser sources are attached to the indirect opthalmoscope. In this set-up, the procedure may be done with the patient sitting down or lying on his back. Endolaser is another way of delivering laser into the eye. It is done during vitrectomy or retinal surgery. This makes use of a fiberoptic probe which is introduced into the patient’s eye, the tip of which delivers the laser close to the retina.
In diabetic retinopathy, focal laser may be employed to seal abnormally leaking vessels to decrease swelling of the retina for conditions such as macular edema. For proliferative diabetic retinopathy where there is growth of abnormal blood vessels in the vitreous cavity, pan retinal photocoagulation (PRP) is usually the treatment of choice. With PRP, the surgeon uses laser to destroy oxygen-deprived retinal tissue outside of the patient’s central vision. While this creates blind spots in the peripheral vision, PRP prevents the continued growth of the fragile vessels and seals the leaking ones. The goal of the treatment is to arrest the progression of the disease. Even with laser, some may still continue to deteriorate. In these cases, other treatment options include surgery or intravitreal steroid injection.
Small holes and tears are also treated with laser surgery. These procedures are usually performed in the doctor's office. During laser surgery tiny burns are made around the hole to "weld" the retina back into place and prevent progression of retinal detachment. One must still take note that laser scars take time to heal (around 2 weeks) so the patient should continue to follow up with his ophthalmologist.
In wet age-related macular degeneration, where there is growth of abnormal vessels causing leakage of fluid into the macular area, a variety of laser procedures are being utilized. Focal “hot” laser is used to seal off abnormal leaking vessels located outside the macular area. On the other hand, Photodynamic Therapy (PDT) or “cold” laser is used to seal off abnormal vessels located under the macular area. It is called “cold” laser because it does not cause coagulation of retinal tissue. This procedure employs the use of a photosensitive dye called verteporfin which is injected intravenously through the arm. The dye is allowed to circulate in the body and later concentrates in the abnormal vessels. The laser is then used to activate the dye, sealing off the abnormal vessels selectively. This way, retinal tissue is spared during the procedure.
4. Transpupillary Thermal Therapy
Transpupillary thermotherapy (TTT) is a laser treatment with minimum intensity photocoagulation (MIP). This means it does not damage the healthy retina tissue surrounding the disease. Therefore, patients can be treated earlier in the disease progression while preserving the maximum amount of vision.
Transpupillary thermotherapy is a method of delivering heat through the dilated pupil into the posterior segment of the eye. This method, using infrared radiation as the heat source, is employed to treat certain intraocular tumors including retinoblastoma and choroidal melanoma. Transpupillary thermotherapy is typically is performed in the office under local anesthesia.
Photodyanamic therapy (PDT) is the latest treatment for choroidal neovascular membranes (CNVM), which are the leaky vascular structures under the retina in the "wet" form of age related macular degeneration (AMD). PDT utilizes an innovative idea to treat CNVM's without damaging overlying or nearby retinal or other ocular tissues.
In PDT, a photosensitive dye known as Visudyne (verteporfin) is administered intravenously (IV) and allowed to perfuse the CNVM, as well as the remainder of the body. Then the ophthalmologist treats the CNVM with a red laser of a specific wavelength for about 90 seconds. The non-thermal laser light activates the Visudyne producing an active form of oxygen that both coagulates and reduces the growth of abnormal blood vessels. This, in turn, inhibits the leakage of fluid from the CNVM.
After Therapy
Because Visudyne acts as a photosensitizer, the effect of sunlight (or ultraviolet light) on the eyes and skin may be greatly enhanced. Therefore, patients should avoid exposure to sunlight for 5 days following PDT to prevent potentially severe sunburn.
The results of PDT with Visudyne are very promising, and certainly should be considered in any patient with new onset "wet" macular degeneration. However, patients with long standing "wet" macular degeneration which has led to scarring are unlikely to benefit. Patients must have realistic expectations for this form of therapy, that PDT is unlikely to restore vision that has already been lost due to AMD.
In cases of diabetic macular edema refractory to laser, intravitreal triamcinolone injection may be performed. This is done under sterile conditions with 0.1 ml of the suspension injected directly into the vitreous cavity. Because the steroid is injected directly into the eye, the effect is almost immediate. Patients notice improvement in vision as early as a few days to 2 weeks after the injection. The effect of the injection may last up to three months after which another injection may be needed.
This procedure however is not without its risks. Infection of the eye called endophthalmitis has been reported in a few cases. For some steroid responders, they develop glaucoma. Still, others may develop or have an accelerated progression of their cataracts.
