Unintended events sometimes happen during cataract surgery that may be reviewed by an eye expert witness. Some complications are benign and resolve within a few days to a few weeks. However, serious complications, particularly those that impact the retina, can endanger vision and significantly affect the final permanent outcome. The way a surgeon handles intraoperative complications can appreciably influence the final results of cataract surgery.
The most common intraoperative complication of significance is rupture of the posterior lens capsule. The lens capsule envelopes the cataract and is responsible for supporting a posterior chamber lens in its proper position. The incidence of posterior capsule rupture is about 1 to 2% of cataract surgeries. Migration of cataract remnants through the posterior capsule rupture adds to the significance of this problem. Cataract remnants that migrate through the rupture in the posterior capsule become trapped in the vitreous – a natural jelly in the area behind the capsule and in front of the retina. Cataract remnants can cause inflammation, elevated eye pressure, and retinal edema.
Inflammation in the eye can irritate the retina and cause cause scar tissue or edema to form in the retina. In many cases removing the migrant cataract remnants by a procedure known as vitrectomy is effective in alleviating these complications. However, persistent inflammation caused by large amounts of cataract remnants in the vitreous can cause a retinal detachment. Retinal detachments are more likely if the cataract surgeon too aggressively removes cataract fragments from the vitreous. Under these circumstances, anterior vitrectomy may result in undue traction of the vitreous on the retina can be another cause of retinal detachment under these circumstances.
Postoperative swelling of the retina, particularly a condition known as cystoid macular edema, occurs more frequently following vitrectomy for retained cataract fragments than after usual cataract surgery, The risk of retinal swelling is still higher if cataract fragments remain in the eye after vitrectomy or when an anterior chamber lens is implanted. When a posterior chamber lens cannot be implanted, many surgeons prefer a sulcus fixated three-piece lens implant over an anterior chamber lens implant. A sulcus-based lens may incite less inflammation and retinal swelling when compared with an anterior chamber implant.
Rupture of the posterior lens capsule can be recognized when vitreous prolapsing through an opening of the lens capsule interferes with cataract surgery. Applying diluted preservative-free traimcinolone-acetonide into the anterior chamber may help the surgeon identify the extent of vitreous prolapse. The efficiency of phacoemulsification is reduced and the cataract does not engage with the instrument as it normally would. Prolapsing vitreous can also lead to an irregular pupil due to displacement of the pupillary edge. Removal of vitreous in the anterior chamber, particularly removal of vitreous incarcerated in the incision, is important. Removal of the vitreous without causing excessive vitreoretinal traction is also important. Lens fragments that pass through the opening in the posterior capsule are usually treated in the immediate post-operative period by a qualified retinal surgeon.
Fortunately, the great majority of patients undergoing cataract surgery do not have complications and have excellent visual results. When unexpected complications occur, it is important that they are managed appropriately in order to optimize visual recovery. Opinions from an eye expert witness is often called on in a peer review process or legal proceedings to review details of the case.