Cataract Surgery in Patients With Well-Controlled Glaucoma

Cataracts are frequently found in eyes with glaucoma. This common problem has many individual solutions. The course of action chosen will depend on the Ophthalmologist’s own patient cohort, surgical experience and the type and severity of the glaucoma. In some cases, the glaucoma and cataract are part of the same process: pseudo-exfoliative glaucoma, uveitic glaucoma, Fuchs heterochromic cyclitis, etc.

In other cases, the cataract appears in a patient previously treated by trabeculectomy, as it has been observed that trabeculectomy can induce cataract formation, particularly if there has been a complication in the immediate postoperative period after filtering surgery (flat anterior chamber, choroidal detachment, etc.).

If the cataract increases in a well-controlled glaucomatous eye and the patient has to undergo surgery, a series of questions should be asked before planning cataract surgery. The most important consideration is that the cataract surgery should not alter the good tensional control that a glaucomatous patient has before surgery.

The controversy of whether a patient with cataract and well-controlled glaucoma should be operated on for cataract or whether combined surgery should be performed is a long-standing debate. General rules cannot be established, rather it is a case of personalising the treatment for each patient.
In this article, we will analyze the factors to consider before cataract or combined surgery. To do this, we will divide the explanation into those eyes with well-controlled glaucoma with medical or laser treatment and those controlled by previous glaucoma surgery.

Well-Controlled Glaucoma With Medical Treatment or Laser Trabeculoplasty

When deciding how to approach cataract surgery in cases of well-controlled glaucoma through medical therapy, the first factor to analyze is the type of glaucoma and the degree of evolution of the perimetric defect. In eyes with simple chronic glaucoma, with hardly any damage to the visual field and control with a small number of medications, cataract surgery does not require a very different approach from routine cataract surgery.

Moreover, in many cases cataract surgery can improve control of glaucoma, as it is well known that many factors such as the increase in depth of the anterior chamber after cataract surgery can reduce intraocular pressure (IOP), although it has never been proved that removing the cataract provides a beneficial long-term effect in the control of glaucoma.

Another possibility is that the glaucoma is controlled, but with visual field damage or scotomas very near the fixation point, or that the IOP is controlled with maximum medical therapy. In these cases, it is advisable to consider the possibility that the high peaks of postoperative IOP may lead to an irreparable increase in the glaucomatous loss. These postoperative IOP spikes depend on the degree of intraocular inflammation, which can be greater in eyes previously treated with miotic drugs. IOP spikes over 35 mmHg have been described in the immediate postoperative period of cataract surgery in glaucomatous patients.

Despite the fact that some drugs can reduce these postoperative spikes (apraclonidine, beta-blockers, etc.) they have not been observed to eliminate them in all patients.

In such cases, it is better to perform combined surgery, which, although may have complications, has shown itself capable of controlling the IOP and preserving the visual field by avoiding these postoperative peaks. If these patients have had laser trabeculoplasty, it should be taken into account that this technique does not eliminate postoperative IOP peaks.

It also seems important to consider the state of the conjunctiva in these eyes.

Many patients instil beta-blockers or miotic drugs for several years, which favours the development of a hyperaemic conjunctiva, blepharitis and dry eye syndrome. Sometimes these patients are elderly with dry eyes, senile ectropion, or have difficulty instilling the drops in their eyes (trembling, etc.). These patients will be relieved (particularly if they have irritation) when they stop using topical treatments. I consider that this type of patient can receive combined surgery.

Finally, the type of glaucoma should be borne in mind before considering cataract surgery. Some forms of glaucoma (e.g. pseudo-exfoliative or uveitic) lead to considerable inflammation with fibrin membranes after cataract surgery. Furthermore, in pseudo-exfoliative (or traumatic) glaucoma, there is a greater possibility of capsular rupture, which would facilitate the IOP increase in the postoperative period. All these characteristics suggest that not all glaucomas produce the same IOP peaks in cataract surgery in the postoperative period.

Well-Controlled Glaucoma With Previous Surgery

As mentioned above, it is often necessary to operate on cataracts in eyes which have previously had one or more filtering procedures. If a patient has a good filtering bleb, with good IOP control, the objective to be achieved is avoiding closure of the trabeculectomy.

This involves some changes to the surgical plan. Many authors share the opinion that it is important to make the cataract incision at a distance from the trabeculectomy. So, if a patient has a superior bleb, a good site for the incision could be on the temporal side. If the incision is made very near the trabeculectomy, alterations of the cataract incision (increase of temperature in phacoemulsification, scar, etc.) may alter the filtration of the aqueous. If 4 retractors have to be placed in the iris, remember that they should not be located near the trabeculectomy for the same reasons as for the incision.

Finally, it is important to consider that fibrinous membranes or haemorrhages in the anterior chamber may close a previously filtering trabeculectomy. Statistics indicate that fibrinous membranes appear in about 40% of previously operated trabeculectomy patients, especially if they have pseudo-exfoliative glaucoma.

I have had some cases in which postoperative inflammation has closed a trabeculectomy which had filtered correctly for a long period of time.
If a fibrinous membrane appears in these eyes, aggressive treatment is required, e.g. subconjunctival steroid injections, topical treatment with sodium diclophenac, subconjunctival 5-fluorouracil injections, or even intra-cameral injections of TPA (although this may cause hyphaema).

What Is the Ideal Cataract Surgery Technique in Eyes With Glaucoma?

There is no doubt that phacoemulsification has become the technique of choice for cataract surgery. On one hand, it produces less inflammation because only a small incision is needed, and on the other hand, it can be done easily on the temporal side if a trabeculectomy is situated in the superior quadrant.

Continuous circular capsulotomy is the best anterior capsulotomy in these cases. Lateral displacement of the intraocular lens (IOL) has been shown in eyes with envelope or can opener capsulotomies.

I also think that capsulorrhexis has to be large to avoid the capsular retraction syndrome, which is more frequent in patients with diabetes, glaucoma or pseudo-exfoliation.

Anterior capsule retraction syndrome

In these cases, I also try to thoroughly clean the anterior capsule once the cataract has been extracted, in order to remove the highest possible number of cortical cells which facilitate the appearance of this syndrome.

In many cases, the pupil does not dilate properly, either because of synechiae, pseudo-exfoliation syndrome, or because the patient has used miotics for a long period. There are many solutions available to extend a pupil. I prefer not to perform sphincterotomies or place iris retractors, because they facilitate postoperative inflammation and hyphaema often appear during surgery.

Iris retractors

A good solution are pupil dilators which enable you to have a 6-7mm diameter pupil, sufficient to perform phacoemulsification without having to pull the iris excessively and create inflammation.

PMMA pupil dilator

The choice of IOL depends on the experience of each surgeon and the characteristics of each eye. A modified surface IOL of heparin can help in eyes where a high level of inflammation is expected, although it has the disadvantage that a wide incision is required. Many authors believe that any of the materials currently available can be used (silicone, acrylic or hydrogel material) although, in the event of fibrin formation, it should be treated immediately.

ntense intraocular inflammatory reaction

Inflammatory debris may sometimes appear on foldable IOLs, although they hardly interfere in postoperative vision. Whenever possible, the implanted IOL should have firm haptics to avoid displacement if a contraction of the capsulorrhexis occurs.

IOL decentration one year after cataract extraction

A good way of avoiding the contraction of the capsulorrhexis is the use of endocapsular PMMA rings. They can be implanted in all eyes with pseudo-exfoliative or uveitic glaucoma or those prone to considerable postoperative inflammation.

They can also be useful in eyes with instability in the zonules or if there is a subluxation of the lens as a result of previous surgery.

Finally, in the event of deciding to perform combined surgery during the intervention, a phacotrabeculectomy can be made on the incision itself, or a different incision can be made for each technique. Both systems have advantages and disadvantages, which should be evaluated in each case. Many authors prefer to perform the trabeculectomy very carefully in these cases, making the sclerotomy with Vannas scissors. If the punch is used, it can inadvertently cut the ciliary body which, if the patient has used certain eye drops, may bleed quite considerably.

Summary

  • Cataract surgery in eyes with well-controlled glaucoma aims to avoid damage to the optic nerve. General rules cannot be made and each case has to be dealt with separately according to the condition of the eye and the type of glaucoma.
  • Postoperative IOP peaks need careful evaluation. In eyes with advanced glaucoma, it is preferable to perform combined surgery at the same time to avoid postoperative IOP spikes.
  • Postoperative inflammation may lead to the closure of a previous trabeculectomy. Good postoperative control and immediate and intense treatment of the postoperative inflammation avoids the failure of previous filtering surgery.
  • Eyes with glaucoma have a greater tendency towards suffering from capsular retraction syndrome and displacement of the IOL. Endocapsular PMMA rings are useful for avoiding this, as is the choice of an IOL with rigid haptics.

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