▪ Several pathologies must be faced: zonular dialysis “of uncertain length,” vitreous herniation through the zonular defect into the central anterior chamber, and an iridodialysis within the lid opening. In addition, there are angle recession and goniosynechias.
What could be the postoperative and intraoperative implications of these pathologies? Because IOP is normal, the traumatic angle deformities described on gonioscopy need not be addressed surgically. The prolapsed vitreous must be removed before phacoemulsification is initiated because aspiration will cause retinal traction and extension of the zonular dialysis. Also, the dialyzed portion of the capsular bag must be supported during lens removal. If not, extension of the zonular defect, profuse vitreous prolapse into the anterior chamber, and capsular bag collapse may ensue. Although not extensive, the iridodialysis, because of its location, may lead to postoperative diplopia.
Before embarking on surgery, I would try to assess the extent of zonular weakening. Looking for possible lens tilt or phakodonesis while asking the patient to make small jerky eye movements or by gently stroking the limbus while the patient looks straight forward may be helpful.
The surgical approach would be as follows: A standard sclerocorneal incision using a bevel-up metal blade entered single plane at the posterior limbus would be performed. The incision would be offset to the 8 o'clock meridian to avoid the area of the iridodialysis. Two paracentesis openings (service ports) would then be prepared at about 11 and 5 o'clock. As the aqueous is replaced with a high-viscosity viscoelastic material, the vitreous would be pushed back toward the dialysis. After lysis of the iridocapsular synechias, a capsulorhexis would be performed with a needle placed through a service port, a forceps, or both.
Because the cortex does not appear intumescent, assistance by a diathermic capsulotome would not be necessary. During this procedure, the resilience of the zonular apparatus can again be assessed. After thorough corticocapsular hydrodissection, complete cleavage is ensured by gently spinning the lens with 2 rotation hooks placed through the service ports. The subsequent placement of a capsular tension ring may be alleviated by extending the cleavage with a low-viscosity viscoelastic material. A straight-tipped ring (e.g., Morcher) would be used to avoid entanglement with the lens cortex.
With the ring in place, the viscoelastic material would be rinsed out and an anterior chamber maintainer (ACM) inserted at 5 o'clock. The main incision would be transiently secured with a suture. A vitreous cutter would then be inserted through the inferotemporal incision and the prolapsed vitreous removed. Vitrectomy would be assisted by a spatula inserted through the superotemporal port, allowing for adequate iris manipulation and searching for and exposing residual strands. The assistant would slowly clamp the ACM infusion line while refilling the anterior chamber with a viscoadhesive material.
Phacoemulsification would be performed using a chop technique to avoid temporal zonular traction while the nucleus is pushed nasally. Before the phaco tip is removed, the ACM would be slowly reopened and residual cortex removed with an aspiration cannula inserted through the service ports. Again, the dialysis would be checked for vitreous strands. As the ACM is clamped, high-viscosity viscoelastic material would be injected above the dialysis to expand the capsular bag. The cataract incision would be widened for IOL implantation.
An acrylic lens (AcrySof MA60BM) would be implanted with a forceps or injector. Acrylic lenses are preferred because fibrotic contraction of the capsule must be minimized. The lens would be positioned horizontally to give additional zonular support. The viscoelastic material would then be rinsed out with acetylcholine, avoiding anterior shift of the capsular plane. Mydriasis caused by iridoplegia may be compensated for by sewing the pupil under viscoelastic material using the sliding knot technique. Increasing the stability of the cataract incision with a suture is recommended.
The iridodialysis can be addressed in 2 ways:
- Before IOL implantation, a second capsular ring with a tinted iris shield could be implanted and rotated until the shield coincides with the iridodialysis.
- Before the viscoelastic material used for IOL implantation in rinsed out, the iris base could be sutured back under gonioscopic control.
Though more efficacious, pars plana vitrectomy should be avoided because the retrolental vitreous also stabilizes the compromised zonular-capsular suspension.