Overview

The prevalence of significant cataract in people ages 65–74 years is greater than 20%, and the prevalence of chronic glaucoma is about 4.5% in people over age 70 years. The 5-year incidence of nucleus cataract in people with open-angle glaucoma and older than 50 years is estimated to be 20%. Patient adherence to treatment with topical glaucoma medication, the most common form of glaucoma treatment, is low.

For these reasons, combining cataract surgery and glaucoma surgery in a single operation appears to be a valid management option. There has been a rapid expansion in recent years in the number of devices, implants, and techniques that are less invasive and are safer than those used in traditional glaucoma surgery. In minimally invasive glaucoma surgery (MIGS), these techniques are increasingly being combined with cataract surgery.

An important consideration is that cataract surgery alone results in an intraocular pressure (IOP) drop of up to 5 mm Hg in patients with glaucoma. Complications after glaucoma surgery may increase the risk of an adverse outcome.

Trabeculectomy and Cataract Surgery

Phacoemulsification (“phaco”) combined with glaucoma surgery probably produces better IOP control with fewer complications compared with manual extraction plus glaucoma surgery, although there are no large well-controlled, randomized studies on this. However, IOP reduction and subsequent control seem to be less effective with combined surgery than with trabeculectomy alone—possibly as a result of more prolonged breakdown of the blood–aqueous barrier associated with cataract surgery. When combined surgery is considered, a single-site approach may be less time consuming, but a two-site approach allows the surgeon to use the familiar temporal clear corneal approach to the cataract. There is ongoing debate as to whether a single-site or two-site approach gives better control, and several studies have reported no significant difference in the IOP-lowering effect.

Nonpenetrating Glaucoma Surgery and Cataract

Nonpenetrating glaucoma surgery (deep sclerectomy with or without viscocanaloplasty) can be combined with phaco. Some studies have reported that these techniques are as effective as trabeculectomy when combined with phaco, but longer-term studies are required to support this claim.

Minimally Invasive Glaucoma Surgery

MIGS is potentially less traumatic and has a higher safety profile compared with conventional surgery. These techniques should involve an ab interno conjunctiva-preserving approach and consequently produce a modest reduction in IOP. Often combined with phaco, in which case it is termed “phacoplus,” the aim of surgery is to reduce the need for topical medications in patients with mild-to-moderate glaucoma. Most studies performed in patients who undergo MIGS in combination with phaco. Because of the large number of patients in this group, the potential market for these products is large. Few trials of sufficient quality exist at present to make firm recommendations. Reviews of the literature are cautious at best. These treatments do offer alternatives to patients with glaucoma, and if studies demonstrate clinical effectiveness over the long term, these techniques may become more universally adopted.

Aqueous Shunts

Aqueous shunts, such as the Baerveldt or Ahmed valve, are indicated in the treatment of more complex refractory glaucoma cases where surgery is required. Phaco can be performed effectively at the time of shunt surgery, although the decision to combine the two procedures has to be made on a case-by-case basis because only small retrospective case series reports are available.

Outcomes

Phaco surgery can be incorporated into many glaucoma procedures. IOP reduction following phacotrabeculectomy is greater than that following cataract surgery alone, although not as great as following trabeculectomy alone. Increasingly, the role of MIGS may offer patients with cataract and early glaucoma the option not to use topical medication following combined surgery, although further study on this is required.

Historical Review

Anterior or posterior lamellar corneal surgery is now much more common compared with penetrating keratoplasty (PKP). Eyes that require keratoplasty often have an associated increased risk of cataract because of the underlying pathology ( Fig. 5.13.1 ); this includes corneal perforation as a result of trauma or infection. Also, age-related corneal degeneration, such as Fuchs’ corneal degeneration, often coexists with age-related cataract. These factors resulted in the development of a variety of techniques for combined primary cataract surgery and keratoplasty (“triple procedure”), or IOL exchange combined with keratoplasty. Combined cataract surgery and lamellar corneal surgery is often referred to as the “new triple procedure.”

(A) Patient with combined corneal and lens opacities. This degree of corneal opacity demands an “open sky” approach to cataract removal. (B) Here, an iris expander device and an “open sky” technique of cataract extraction are used. (C) “Open sky” cataract extraction performed. (D) Combined cataract extraction with intraocular lens (IOL) implantation and penetrating keratoplasty.

Surgical Options

A retrospective analysis of eyes that underwent PKP for Fuchs’ endothelial dystrophy, with an average follow-up period of 6 years, showed an incidence of significant cataract in 75% of patients over 60 years of age. In those who subsequently required lens surgery, 13% lost transplant clarity postoperatively. Two recent reports following Descemet’s stripping endothelial keratoplasty (DSEK) showed the presence of cataract in 40% at 1 year in one study and cataract extraction rate of 31% and 55% at years 1 and 3, respectively, in patients over 50 years of age. Similarly, studies following Descemet’s membrane epithelial keratoplasty (DMEK) showed a 76% progression of cataract. Following DSEK/DSAEK the endothelial cell loss rate can be as high as 56% in the first year, although with standardized technique, the endothelial cell loss has been reduced to less than 35%. In patients undergoing DMEK, the endothelial cell count loss at 1 year is in the range of 25%. Multiple reports have suggested that combined cataract surgery and endothelial grafts (DSAEK and DMEK) were not associated with any increased complication rate or endothelial cell loss. Therefore, an argument exists for not subjecting such a cornea to multiple surgeries. The decision in individual cases depends on the balance of the risks and benefits. One key decision for the clinician is whether it is possible to determine if the main barrier to good vision is the cornea or the lens. Another is the likelihood of development of frank decompensation if keratoplasty is not carried out. A combined approach may be the best choice in either circumstance.

Choice of IOL depends on individual circumstances. In the event that cataract surgery is part of the primary procedure, a standard IOL can be placed in the capsular bag. If sufficient capsular and/or zonular support exists, then the best option is a capsule or sulcus-placed posterior chamber IOL. If adequate support is not available, then the choice is a posterior chamber IOL, either transclerally sutured or iris sutured.

Biometry and IOL power calculation is problematic if PKP or lamellar keratoplasty is combined with cataract surgery. The refractive impact of DSEK, however, is reasonably consistent, with a hyperopic shift of 0.75–1.5 D, although this is much less with thinner grafts. With the use of DMEK, where little or no stroma is transplanted, the surgery causes even less change in the refractive power.

Specific Techniques

The techniques of keratoplasty are dealt with elsewhere. A significant recent trend is toward either anterior or posterior lamellar keratoplasty, and significant benefit is obtained by the cataract surgeon in these closed-chamber techniques. The ongoing audit of keratoplasty conducted by the Corneal Graft Registry of the National Health Service (NHS) – Blood and Tissue, in the United Kingdom, has shown that during 2010, 26% of the surgeries performed were deep posterior lamellar keratoplasty, 15% were deep anterior lamellar keratoplasty (DALK), and 56% were DSEK, with the number of endothelial keratoplasty procedures increasing.

Phaco surgery can be difficult because of the poor visibility as a result of the corneal disease. Selected cases with stromal opacity (see Fig. 5.13.1A ) may be suitable for a routine phaco procedure after DALK and use of an ophthalmic viscosurgical device in the bed to restore anterior chamber and capsule visibility. In cases of endothelial disease where the stromal clarity is reasonable, a combined phaco with DSEK/DMEK is now the preferred technique (Video 5.13.1 ). This offers much quicker visual rehabilitation and more predictable refractive outcome than combined PKP and phaco.

Such an approach is not always possible, and “open sky” removal of the lens may be required. The altered anterior-chamber and lens–iris diaphragm dynamics, abnormal light reflexes present in the “open sky” situation (see Fig. 5.13.1 ), and difficulty in controlling the anterior and posterior capsule increases the risk of surgical complications. Capsulorrhexis can be difficult because of decreased anterior pressure caused by the “open sky.” Careful use of scissors can be of help. The nucleus is expressed manually after thorough hydrodissection. Manual irrigation–aspiration of the cortex is carried out with the use of a cannula, such as the Simcoe cannula.

When specific endothelial keratoplasty techniques are combined with cataract surgery, certain additional risks, such as pupil abnormalities and lens subluxation or dislocation, arise either because of the effect of the air tamponade or anterior chamber depth modulation needed in these surgeries.

Complications

Apart from the possible inherent complications of keratoplasty, the combined procedure carries an increased risk of cystoid macular edema. Other complications of combined procedures are the variability of refractive outcome and the delayed visual rehabilitation compared with straightforward cataract surgery. Weighed against this, however, is the additional risk of graft failure inherent in the alternative of a two-stage procedure.

Outcomes

There are currently no definitive studies providing hard evidence of the benefit of one approach over another, but with the development of standardized techniques of corneal graft surgery, the new triple procedure shows very similar results to the two-stage approach.