Complications in Vitreoretinal Surgery
Good judgment is to make the best decision based on the known information in hand, and it is a product of experience. However, experience usually comes from the lessons learned from previously made bad judgments. As surgeons we are trained to predict and treat expected events during surgery. Unexpected events; however, are fact of life and generally the question is not if they will happen but when they will happen. They are frequently dangerous and can lead to undesirable outcome.
The knowledge of how to predict, treat, and prevent unexpected events during surgery is extremely valuable and would make vitreoretinal surgery safer, leading to improved visual outcome in patients. The more one is acquainted with unexpected events, the less they are considered unexpected since one has already seen these events happen and knows how they were handled and therefore the factor of surprise is eliminated.
In this chapter, experienced surgeons from around the world share with you their unexpected experiences during retinal surgery and show how they handle some of the most unusual surgical cases. Further, they share their surgical pearls on how to predict, prevent, and treat these unusual surgical cases.
Always Measure Prior to Trochar Insertion
Vitrectomy surgery with trochar systems reduces conjunctival trauma, scleral manipulation, iatrogenic peripheral breaks, postoperative inflammation, and corneal astigmatism.
Precise measuring of the location of the trochar insertion is crucial to assure a pars plana entrance into the eye, especially when utilizing an oblique insertion technique. Further, it is important that the insertion tunnel is parallel to the limbus so that the distance between the entrance point into the eye and limbus is the same as the scleral insertion point and limbus.
An insertion that is too anterior to the limbus (less than 3 mm posterior to the limbus) leads to an inadvertent insertion into the cilliary body which is very vascular and may cause bleeding as shown in the video(case 1). An anterior insertion may also lead to cataract formation or intraocular lens implant dislocation. In these cases the cannula needs to be removed and re-inserted.
An insertion that is too posterior to the limbus, (more than 4 mm posterior to the limbus) may lead to a subretinal trochar insertion inducing retinal breaks and retinal detachment (case 2). In these patients the iatrogenic breaks need to be treated similar to other peripheral breaks: thorough peripheral vitrectomy, endolaser, and tamponade.
It is important to always measure the distance of the trochar insertion form the limbus (range 3-4 mm posterior to the limbus depending on the lens status). One may use either a caliper or the other side of the trochar inserter (which also serves as a caliper) for measuring. If the trochar is not inserted at a correct distance to the limbus it should be removed and re-inserted correctly.
Suprachoroidal Infusion
Suprachoroidal infusion is a serious intra-operative complication during vitrectomy surgery. This complication has become more prevalent with the use of trochar systems.
At the beginning of the surgery, it is important to visualize the tip of the infusion cannula in the vitreous cavity prior to opening the infusion line. A well-constructed scleral wound may also prevent the dislodgement of the infusion cannula during surgery.
If the tip of the infusion cannula is dislodged into the suprachoroidal space during the surgery one should immediately stop the flow the infusion into the eye. Generally, the infusion needs to be re-inserted into the eye through a different trochar. Pulling back the original infusion trochar slightly outwards so that its tip is placed in the suprachoroidal space may help the draining of the suprachoroidal fluid. Many times the residual fluid in the suprachoroidal space can be left alone.
Subretinal Insertion of Endo-illuminator
Patient underwent combined vitrectomy surgery and scleral buckling for a total retinal detachment with PVR. The inferotemporal trochar was inserted and after the visualization of the tip of the infusion cannula, the infusion line was opened. As the endo-illuminator was inserted into the eye through the trochar (tunneled incision), it was noted that it was placed under the retina. The endo-illuminator was removed and the cannula was examined and the tip of the cannula was under the pars plana (video#1).
To resolve this situation one option would be to remove the trochar, suture the sclerotomy, and re-insert the trochar through a new sclerotomy. The simpler option is shown in the video #2:
The trochar was removed and re-inserted through the same sclerotomy without tunneling the incision (inserted almost perpendicular to the sclera). At this point, the tip of the endo-illuminator could be easily visualized. At the conclusion of the surgery the sclerotomy was sutured.
In the presence of pars plana detachment or hypotony the tunneled trochars could be placed under the pars plana. In these cases one may avoid tunneling the incision and insert the trochar perpendicular to the sclera. These sclerotomies would require suturing at the conclusion of surgery.
Dislocated IOL and Capsular Tension Ring
The patient was presented for the removal of a dislocated intraocular lens implant (IOL) after a difficult phaco-emulsification. During the surgery, after the IOL removal it was noted that the patient also had a capsular tension ring. Removal of the ring can be challenging due to their large size and their elasticity. They may also have extensions that can induce traction to the peripheral vitreous. It is important to remove the ring gently to minimize traction and to remove it by rotating it (rather than pulling it) out of the eye. In patients who present with a dislocated intra-ocular lens, after the removal of the lens it is important to inspect the anterior pars plana very carefully for the capsular tension ring. It can be difficult to detect and (if missed) may dislocate into the vitreous cavity over time.
Iatrogenic Breaks during the Induction of Posterior Vitreous Detachment
Formation of peripheral breaks during the induction of posterior vitreous detachment (PVD) in a patient with macular hole is demonstrated. If these patients generally have a very adhesive vitreous, the induction of PVD may induce peripheral breaks. The use of wide angle viewing system would allow the monitoring of peripheral retina during the induction of PVD.
At the beginning, the surgeon is paying attention to the optic nerve and the grasping of the Weiss ring. Once the Weiss ring is grasped and the PVD is in process of expanding, attention must be given to the peripheral retina to identify the location of the anterior vitreous base. This is the location where the vitreous can no longer be separated and breaks will form if suction/traction is applied.
In these patients it is extremely important to screen the periphery at the conclusion of the surgery. In the presence of peripheral breaks, a thorough peripheral vitrectomy should be performed around the breaks to relive any residual traction, followed by retinopexy, and possibly a tamponade agent.
Iatrogenic Macular Hole during VMT Surgery
This video illustrates the dangers of excessive traction on the fovea while detaching the posterior hyaloid in a case of vitreomacular traction syndrome, or VMT.
VMT is characterised by the presence of a partial vitreous detachment with strong adhesions to the macula, especially the fovea.
This patient had a long history of reduced vision. While using active aspiration over the disc to detach the hyaloid the surgeon is focused on looking for signs of vitreous separation from the disc rather than the traction vectors at the fovea as the fovea tissue is stretched before finally separating. In fact the central lucent area was assumed to be a cyst as no hole was present pre-operatively.
To summarize, observe the fovea closely while detaching the hyaloid in conditions with foveal thinning and strong vitreoretinal adhesions such as vitreomacular traction syndrome. In the presence of significant vitreo-macular adhesion and/or cystic macular changes one may trim the vitreous around the macular area rather than peeling it, leading to the un-roofing of macula.
