Averting zonular crises in different types of cataract patients

The condition zonulopathy can result from a number of situations. In the case of pre-existing pathology, the patient may have had trauma or pseudoexfoliation syndrome, which causes progressive zonulopathy. This can lead to IOL subluxation and, indeed, dislocation years later. 

High myopia is another risk factor, whilst syndromic problems such as Marfan syndrome, homocystinuria and ectopia lentis also need to be considered. Intraoperative problems can arise with zonules: either iatrogenic or a pre-existing zonulopathy that had been undiscovered in the preoperative examination.

When managing cases with zonular compromise, one has to assess the degree of zonulopathy, however, a lot of other factors also need to be considered. One of the problems when looking for zonulopathy is that, if you dilate the pupil, the ciliary body or the ciliary ring is put under tension and subtle degrees of phacodonesis can sometimes be missed. 

Increasing numbers of cataract clinics take place with pupils pre-dilated, but I think it is our duty to look for signs of phacodonesis and iridodonesis. I always tell my juniors that if they see a male patient with a unilateral cataract, they should consider trauma.

It is also important to be aware of the degree of clock hours of zonulopathy, presence of vitreous in the anterior chamberand, particularly in trauma eyes, IOP. In addition, the patient should be assessed in the supine position. This is because sometimes, a subluxed cataract, with the patient in the supine position, may appear to be in a totally different position from where it was viewed on the slit lamp. This can be unnerving.

Challenging cases

Case study 1: Small pupil,brunescent cataract, pseudo-exfoliation with phacodonesis

Incases like this I shake the eye to ascertain the degree of phacodenesis before making a temporal incision. Before mechanically dilating the pupil with the Malyugin Ring (MicroSurgical Technology; MST), I inject Viscoat dispersive ophthalmic viscosurgical device (Alcon) to protect the cornea.

I then create a capsulorhexis, painting trypan blue onto the capsule before starting it. When this is done, I hook the capsule using capsule retractors (MST), which are really good for dealing with difficult cases and essentially give you four-point broad fixation.

In this case, the lens is fairly dense. I like to debulk these lenses centrally and then use a shelf at the end to do a phaco chop manoeuvre.

I then insert the capsular tension ring. I like to do all these manoeuvres, which can put torque and tension on the remaining zonules, with the capsule retractors on; in fact, I keep them on right until the lens is in, and then I remove them. Then you remove the Malyugin Ring and the case is completed.

Case study 2: Ectopia lentis

This case was a monocular patient in her 40s. Rather than referring the patient to a vitreoretinal department for vitreolensectomy, a better tactic is to approach from the anterior segment because there is no vitreous in the anterior chamber.

You can actually perform a capsulorhexis on the subluxed lens. You have to centre the capsulorhexis on the lens and not on the pupil. Once you have completed the capsulorhexis, you will be surprised how much strength these few zonules still give you.

I put a couple of iris hooks on just to support the area of zonular weakness and then carry out the hydrodissection, prolapsing the lens out of the bag into the anterior chamber. Phaco then proceeds relatively easily.

It is important that the chamber does not collapse, so I use viscoelastic to pump up the anterior chamber, pushing the capsule back and preventing vitreous prolapse. Once the cataract has been removed, the bag is fixated to the sclera using a capsular tension segment.

I make a mark a couple of millimetres back from the limbus and put the tension segment into the eye to fixate the capsular bag to the sclera. I use an 8/0 Gore-Tex suture (WL Gore & Associates), which is passed through the eyelet and then docked with a needle on the other side using the 23g MST micro-holding forceps (MST).

I then pull the suture through. Once I have got itthrough the eyelet, placing the second needle is relatively easy because I am operating outside of the eyelet. I end up with a loop of Gore-Tex around the eyelets of the segment and pull the lens into the capsular bag in a more central position.

I tie the Gore-Texoff with a couple of slip knots and put a capsular tension ring in for circumferential support of the zonules of the capsular complex. Then I place the IOL into the capsular bag and finally lock the knot on the suture once I am happy with the position of the lens.

This patient has done very well and ended up with 6/6 vision unaided, without going into the vitreous cavity.

Conclusion

Zonular crises can occur due to many different aetiologies, but we have multiple tools at our disposal to solve complex problems, and excellent outcomes are achievable.

Imran Masood, BSc, FRCOphth, MBChB, MRCSEd

E: imranmasood777@gmail.com

Mr Masood completed his fellowship at the Royal College of Ophthalmologists and has undergone training in the management of complex glaucoma at the Moorfields Eye Hospital, UK. He is currently a consultant ophthalmic surgeon at Optegra Eye Hospital in Birmingham, UK. His financial disclosures include lecture fees fromMST, Glaukos and Sight Sciences.