Posteriorly dislocated cataracts are usually removed via a posterior segment approach; however, meticulous removal of the vitreous is required to avoid retinal complications. We present an anterior segment approach that minimizes vitreous loss.
CASE PRESENTATION
A 53-year-old man from Cambodia, complaining of decreased visual acuity in his right eye, visited our practice 1 month after he had been injured by an exploding car battery. His attending physician in Cambodia prescribed topical dorzolamide HCL, timolol maleate, (Cosopt; Merck & Co., Inc., Whitehouse Station, New Jersey) and prednisolone acetate 1% three times daily for his right eye. On examination, his BCVA was 0.3 in his right eye and 1.0 in his left. There was a grade 1 reverse relative afferent pupillary defect.
Slit-lamp biomicroscopy showed a 7-mm fixed dilated pupil with multiple sphincter ruptures. The grade 2+ nuclear sclerotic cataract had entirely dislocated posteriorly and was displaced into the anterior vitreous cavity. Vitreous prolapse was seen both nasally and medially in the anterior chamber, leaving only a small zone of unobstructed access to the anterior capsule (Figure 1). The patient's intraocular pressure (IOP) was 17 mm Hg in the right eye and 19 mm Hg in the left. On fundus examination of the right eye, the cup-to-disc ratio was 0.4, and there was bleached vitreous hemorrhage inferiorly; however, the retina was flat and there were no retinal breaks. Despite his dilated pupil, the patient did not experience glare.
HOW WOULD YOU PROCEED?
The issues to be addressed in this case included: (1) removing the cataractous lens which has no zonular support, is dislocated posteriorly, and has a large amount of vitreous in front of it, (2) choosing the proper IOL fixation technique, and (3) managing the dilated pupil.
Removal of the dislocated cataract. The options for cataract removal in this patient include: (1) intracapsular cataract extraction via a corneal section, (2) phacoemulsification, or (3) pars plana lensectomy.
Before deciding upon a surgical approach, one must consider the patient's current use of glaucoma drops—indicating that his IOP was previously elevated. In this case, the superior conjunctiva should be preserved for possible future glaucoma surgery.
The posterior displacement of the cataractous lens may preclude access from the anterior segment. The feasibility of an anterior approach may be assessed preoperatively by having the patient lie in a supine position. Once the patient is positioned, a handheld slit lamp can be used to estimate the depth of the lens. An intracapsular approach requires less instrumentation and also permits implantation of an iris diaphragm IOL; however, the requirement of a large incision increases the risk of further vitreous prolapse, inflammation, secondary glaucoma, and induced astigmatism.
A clear corneal phacoemulsification technique is preferable because it spares the conjunctiva and allows rapid visual recovery. The large amount of vitreous in front of the patient's lens should be cleared, thus enabling creation of the capsulorrhexis. Giving the patient a hyperosmotic agent (eg, mannitol) preoperatively will shrink the vitreous; however, it may also cause the lens to sink out of reach from the anterior segment surgeon. Removing the anterior vitreous with an automated vitreous cutter at this stage may result in a similar situation. The complete absence of zonular support also makes it challenging to stabilize the capsular bag and create countertraction during the initiation of the capsulorrhexis. Iris hooks and/or capsular tension segments may be subsequently inserted to maintain capsular stability.
Pars plana lensectomy is familiar to vitreoretinal surgeons. This procedure, which preserves the superior conjunctiva, would be the approach of choice if the lens were displaced too far posteriorly.
IOL fixation techniques. The available options include: (1) an angle-supported or iris-claw anterior chamber IOL or (2) a posterior chamber IOL. Within the latter category, scleral fixation, iris fixation (with a suture or clip), or capsular implantation of the IOL with endocapsular support are possible choices. All of these fixation techniques can cause persistent inflammation with a risk of further IOP elevation.
Anterior chamber IOLs are easier to implant, and new designs, including the flexible open-loop angle-supported IOL or iris-claw IOLs, have comparable outcomes to scleral fixated IOLs;1-3 however, the significant iris damage and possible angle recession in this case make them a relative contraindication.
Scleral-fixated posterior chamber IOLs are more difficult to implant and may tilt or decenter. Suture erosion or breakage, vitreous hemorrhage, scleral necrosis, and endophthalmitis may also occur.4,5
Iris fixation of a posterior chamber IOL is technically less demanding and circumvents the risk of scleral track infections; but this patient may not have enough healthy iris tissue to support an iris-fixated posterior chamber IOL.
Pupil repair. There are three options for pupil repair: (1) pupilloplasty with a purse-string encirclage or segmental repair, (2) iris segments, or (3) an iris diaphragm IOL.
Pupilloplasty is a simple and effective procedure in cases with limited iris loss and a sufficiently healthy residual iris. Iris segments are inserted through a small incision but require adequate capsular support. Because this patient has no zonular support, at least three capsular tension segments would be required to support the two interdigitating iris segments and an IOL. An additional concern is the patient's ethnicity, as access into the eye of an Asian patient is somewhat limited. Because of the patient's vitreous hemorrhage, the final pupil diameter should be at least 5 mm, allowing satisfactory examination of the fundus. To reduce a 7-mm pupil to 5 mm with iris segments may not be the most cost-efficient option. An iris diaphragm IOL can be fixed to the sclera, but it requires a large incision with the attendant risks previously discussed.
If this were your patient how would you proceed?
HOW WE PROCEEDED
We discussed the risks and benefits of each option, in detail, with the patient. Together we decided upon phacoemulsification followed by multiple segmental pupilloplasties and iris fixation of a posterior chamber IOL. We generally prefer segmental repair to encirclage because it still allows reasonable pupil dilation.
The surgery was performed under general anesthesia. We administered intravenous mannitol preoperatively to prevent further vitreous presentation.
After creating four paracenteses, we inserted the Ahmed 23-gauge, curved micrograsper forceps (MicroSurgical Technology, Inc., Redmond, Washington) without prior ophthalmic viscosurgical device (OVD) injection, thereby avoiding further posterior displacement of the lens. We directed the forceps posteriorly, grasping the anterior capsule in the gap with no overlying vitreous, and elevated the lens into the iris plane.
The capsulorrhexis was performed using a two-hand technique holding the capsule with the micrograsper forceps, thus supporting the lens and providing countertraction to the tearing forces. We used the sharp-tipped Kawai capsulorrhexis forceps (ASICO LLC, Westmont, Illinois) to puncture the anterior capsule; however, the tear was unsuccessful in this patient because of the lack of zonular support. The capsulorrhexis could be initiated only by gently pulling the capsule apart between the two instruments to create sufficient tension in the capsule. This allowed the sharp tip of the capsulorrhexis forceps to cut the capsule (Figure 2). The vitreous anterior to the lens was then displaced with Viscoat (Alcon Laboratories, Inc., Fort Worth, Texas), with the micrograsper still holding onto the capsulorrhexis edge to prevent descent of the lens. We completed the capsulorrhexis with a hand-over-hand holding and tearing technique and placed five pupil hooks to ensure sufficient stability of the capsular bag (Figure 3).
Gentle and complete hydrodissection and hydrodelamination are crucial in cases such as this. These techniques ensure successful removal of the nucleus in the absence of zonular counterforce, which prevents collapse of the capsular bag during phacoemulsification in normal eyes.
The relatively soft nucleus was aspirated with minimal stress on the capsular bag, and further vitreous prolapse was avoided. After the epinucleus and cortical material were easily removed, as a result of our meticulous hydrodissection (Figure 4), we removed the iris hooks and the capsular bag. Next, we performed an anterior vitrectomy to clear the small amount of vitreous still present in the anterior chamber. At this point, we noted an area of iridodialysis between the 6- and 8-o'clock positions, and we decided to use scleral rather than iris fixation of the posterior chamber IOL. We raised two conjunctival and partial thickness scleral flaps at the 1- and 7-o'clock positions and placed an AcrySof IOL (Alcon Laboratories, Inc.), securing the haptics with 10-0 Prolene sutures. By passing through the scleral flap at the 7-o'clock position, the sutures also incorporated the iris root, thereby repairing the iridodialysis in that area. Pupilloplasty could not be completed because, in the process of placing the sutures, another area of iridodialysis was revealed between the 10- and 12-o'clock positions (Figure 5). We repositioned the scleral flaps and closed the conjunctiva with 8-0 virgin silk.
FOLLOW-UP
At the patient's latest follow-up (1 month postop), visual acuity was 0.7 in the right eye (refraction, -0.75 -0.25 X 20) and the IOL was well centered and stable (Figure 6). His IOP, which had been normal on no medications postoperatively, was 27 mm Hg. We restarted him on Cosopt, and he remains untroubled by glare or photophobia.
WHAT HAVE WE LEARNED FROM THIS CASE?
This was an extremely challenging case for an anterior segment surgeon; however, it demonstrated that a posteriorly displaced lens could be removed through an anterior segment approach—even with a large amount of vitreous in front of it—provided it had not gone too far back. Although we chose a difficult and time-consuming approach, the procedure resulted in minimal vitreous loss by combining hyperosmotic agents and an OVD to reposit the vitreous. The maintenance of a stable capsular bag also aided in preventing further vitreous from presenting.
The most difficult part of this case was the initiation and completion of the capsulorrhexis. The lens had to be stabilized to prevent further posterior displacement, and the lax anterior capsule was difficult to puncture with conventional techniques. We found the two-hand technique using the two forceps to be effective in this situation.
In traumatized eyes, such as in this case, unexpected findings may arise intraoperatively. These patients should be informed that a two-stage procedure may be necessary. Additionally, preoperative gonioscopy helps to assess the viability of an iris-fixated IOL.
Soon-Phaik Chee, MMed(Ophth), FRCS, FRCOphth, FRCS(Ed), practices in the Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore; Singapore National Eye Centre; Singapore Eye Research Institute; and Singapore General Hospital. Dr. Chee states that she has no financial interest in the products or companies mentioned. She may be reached at tel: +65 6227 7255; fax: +65 6226 3395; e-mail: chee.soon.phaik@snec.com.sg.
Aliza Jap, FRCS, FRCOphth, practices at the Changi General Hospital, Singapore. Dr. Jap states that she has no financial interest in the products or companies mentioned. She may be reached at tel: +65 6788 8833; fax: +65 6260 8473; e-mail: aliza_jap@cgh.com.sg.
