Questions
- 1.
What are the different types of retinal detachment?
- 2.
Briefly describe the different types of retinal detachment repairs.
- 3.
Which patients are at risk for retinal detachment?
- 4.
What are the advantages and disadvantages of general anesthesia versus regional anesthesia?
- 5.
What are the different regional anesthesia options?
- 6.
What are the considerations for general anesthesia?
- 7.
What is the oculocardiac reflex, and how is it treated?
- 8.
What is the implication of injecting a “gas bubble” into the eye?
A 36-year-old man presented for repair of right retinal detachment. He had been hit in the eye with a baseball. The patient was otherwise healthy, and he never had surgery.
1
What are the different types of retinal detachment?
There are three types of retinal detachments: rhegmatogenous, exudative, and tractional. Rhegmatogenous is the most common type and is caused by disruption of the retina, allowing fluid to enter the subretinal space. Exudative retinal detachment is rare and occurs when there is an accumulation of fluid in the subretinal space without an obvious disruption of the retina. Tumors in the layers beneath the retina, such as choroidal melanoma, produce exudative retinal detachment. The third type of retinal detachment is a tractional detachment that occurs when fibrous or fibrovascular tissue caused by injury or inflammation pulls the retina away from subretinal layers.
2
Briefly describe the different types of retinal detachment repairs.
Methods employed for repair of retinal detachments are scleral buckle, pneumatic retinopexy, or vitrectomy. In some instances, more than one method is necessary. The endpoint of all of these procedures is to repair the interruption of the retina, create an adhesion between the retinal pigment epithelium and the retina, and prevent recurrence of the detachment.
Surgical approaches vary depending on the method selected. Although pneumatic retinopexy and vitrectomy are intraocular procedures, scleral buckles are extraocular. Pneumatic retinopexy involves injection of a “gas bubble” into the vitreous cavity followed by cryopexy or laser photocoagulation to seal the retinal detachment. After the procedure is completed, the patient is positioned so that the “gas bubble” is abutting the repaired retina. For example, if the retinal detachment is in the 12-o’clock position, the patient would be required to remain in the upright position for 3–5 days.
The purpose of the scleral buckle is to change the internal contour of the globe by external manipulation. The inward displacement of the external tissue by the scleral buckle closes the retinal disruption, preventing the passage of liquefied vitreous into the subretinal space. It is controversial whether or not draining the subretinal fluid should be done during the procedure. Proponents of draining the fluid believe that the decreased intraocular volume allows for the inward displacement by the scleral buckle without increasing intraocular pressure; this also allows the detached retina to rest on the scleral buckle, facilitating reattachment.
Vitrectomies involve removal of vitreous gel, relieving traction on the detached portion of the retina. Sometimes the release of traction is insufficient to allow the retina to reattach. After vitrectomy, vitreous gel is replaced with silicone oil or a “gas bubble” to restore normal pressure in the eye. Depending on the size and location of the retinal detachment, pneumatic retinopexy may also be necessary.
3
Which patients are at risk for retinal detachment?
Several conditions predispose patients to retinal detachments. Among the ocular conditions associated with retinal detachments, high myopia (> 6.0 diopter) is associated with almost a threefold increase in incidence. Retinal detachment is a known complication of cataract surgery. Cytomegalovirus retinitis, most often seen with acquired immunodeficiency syndrome (AIDS), predisposes patients to retinal detachments. Ocular trauma is the cause of 10%–15% of retinal detachments and is the most common cause in children. Another common cause of retinal detachment in children is retinopathy of prematurity. Patients with a history of retinal detachment from intraocular pathology in one eye have a significant risk of retinal detachment in the other eye.
4
What are the advantages and disadvantages of general anesthesia versus regional anesthesia?
Selecting the appropriate anesthetic for any retinal surgery should be specific to each patient, the underlying medical conditions, and the intended procedure. Discussion with the ophthalmologist regarding surgical needs and patient expectations also helps in deciding what type of anesthesia would be best suited.
There are several methods of providing adequate operating conditions using regional anesthesia (retrobulbar, peribulbar, sub-Tenon block) with or without sedation. However, because some of these complex repairs may take >2 hours and patients may be unable to tolerate lying motionless, it may be necessary to provide general anesthesia to ensure patient safety, satisfaction, and the best opportunity for a good surgical outcome ( Table 41-1 ).
