The patient with corneal disease and cataract necessitates several management decisions. First, the clinician must determine how much visual loss is due to the cataract and how much to corneal opacification. The latter may be the result of epithelial, stromal, or endothelial disease. In the case of epithelial disease, it is often best to eliminate any epithelial pathology prior to cataract extraction. Removing the abnormal corneal epithelium will significantly improve the clinician's ability to obtain accurate keratometric measurements and may greatly enhance the patient's visual acuity.
The majority of cases, however, involve stromal opacification and endothelial disease—most notably, stromal scarring due to dystrophies, degenerations, or previous infections. The most common endothelial abnormalities are dystrophic endothelial changes such as Fuchs' dystrophy or posterior polymorphous dystrophy (Figure 1). In addition, some patients lose endothelial cells due to trauma. Either blunt trauma to the globe or previous surgical trauma from anterior segment surgery such as trabeculectomy or the placement of a tube shunt may result in significant endothelial cell loss. In these cases, the clinician must determine if corneal opacification, cataract, or both are significant causes of the visual loss.
THE TRIPLE PROCEDURE
For the last 2 decades, most corneal surgeons have advocated the triple procedure for patients with concomitant corneal disease and cataract. The technique combines a penetrating keratoplasty (PKP), cataract extraction, and PCIOL implantation. The triple procedure itself has changed during the last several years. Initially, it used the “open sky” technique in which the surgeon excised the recipient cornea, performed extracapsular cataract extraction, placed a PCIOL, and sutured the donor cornea (Figure 2). The procedure's advantages included the ease of cataract extraction, the reduced surgical time, and the better visibility of the lens owing to the removal of the corneal pathology. In some cases of dense corneal opacification, the open sky technique was the only option. Certainly, this technique had disadvantages, however. Because the cornea was removed at the time of cataract surgery, patients with any significant posterior pressure ran the risk of anterior and posterior capsular tears with subsequent vitreous loss. In addition, the risk of posterior chamber lens dislocation due to increased posterior pressure could be significant.
More recently, surgeons began performing the triple procedure with standard phacoemulsification, either through a clear corneal incision or a scleral tunnel incision. After implanting the PCIOL, the surgeon constricts the pupil and completes the PKP. The advantages of this form of the procedure include more controlled cataract extraction and lens placement, less risk of capsular tear, and a shorter time during which the eye is “open.” Its disadvantages include a slightly longer surgical time (compared with the traditional triple procedure) and a second incision made in the eye. Moreover, in some eyes with severe corneal pathology, it is difficult to visualize the lens.
Overall, the advocates of the triple procedure emphasize that patients require a single surgery, which is also less expensive. In addition, the technique avoids traumatizing the donor endothelium, unlike subsequent cataract extraction and lens implantation. Finally, they argue that the triple procedure reduces the delay in patients' visual rehabilitation by addressing their cataract at the time of corneal surgery.
Advocates of the technique, however, disregard its major disadvantage: the clinician is unable to predict the final keratometric reading. This problem results in inaccurate IOL calculations and anisometropia due to high refractive errors. Overall, the refractive results are unacceptable, as a review of the literature from the last 20 years demonstrates. The ranges of spherical equivalent found include -6.88 to +7.89D by Katz et al,1 -5.50 to +6.62D by Crawford et al,2 -9.75 to +12.88D by Flowers et al,3 and -6.00 to +5.00D by Djalilian et al.4 In addition, the number of patients within 2.00D of the desired refractive power has been low. In the nine studies published since 1985, the best outcome was that 63% of patients were within 2.00D of the desired power,4,5 and the worst was that only 26% of patients were within 2.00D1 (Table 1).
PKP AND SUBSEQUENT
About the Technique
Because of the broad range of refractive errors and the clinician's inability to predict the final refractive outcome, many patients undergoing a unilateral or bilateral triple procedure are quite unhappy. Clinicians currently are evaluating a technique of PKP and subsequent phacoemulsification with PCIOL implantation. In this procedure, the surgeon performs the PKP first and does not address the cataract at that time. All sutures are removed approximately 10 to 12 months later, depending on the age of the patient and how fast the wound heals. After the keratometry and topography readings have stabilized, the patient is scheduled for routine phacoemulsification and PCIOL implantation.
Advantages and Disadvantages
I believe that the advantages of PKP and subsequent phacoemulsification with PCIOL implantation outweigh its disadvantages. With this technique, clinicians can take exact keratometric measurements that lead to accurate IOL calculations, thereby reducing the incidence of anisometropia and high refractive errors. In addition, at the time of cataract surgery, there is an opportunity to reduce any corneal astigmatism with surgical techniques (eg, limbal relaxing incisions) and the placement of a toric IOL. PKP and subsequent phacoemulsification/PCIOL placement produce excellent refractive outcomes.
The potential disadvantages of this technique are that it involves two surgeries on the same eye and the cost of the second operation. Many patients whose refractive outcomes after the triple procedure are poor must undergo multiple procedures to correct their significant refractive errors, however. Another potential disadvantage of PKP followed by phacoemulsification with PCIOL implantation is trauma to the donor endothelium of the corneal transplant. With modern phaco surgery and newer viscoelastics, however, it appears that cataract surgery can be safely performed without causing significant trauma to the endothelium. The technique's final disadvantage is that it delays visual recovery until the cataract is removed. Nevertheless, despite earlier cataract removal, the visual recovery of patients who undergo the triple procedure is delayed 6 to 12 months until all of the sutures have been removed. High ametropia and anisometropia after the triple procedure also delay visual recovery until they have been addressed.
A study by Shimmura et al9 involved a prospective trial of patients with concomitant corneal disease and cataracts. Twenty-two eyes were randomized to either a triple procedure or PKP with subsequent phacoemulsification. Postoperatively, four of 11 eyes (45%) that underwent a triple procedure were within 2.00D of the desired spherical equivalent compared with 10 of 11 eyes (91%) in the PKP/phaco group. The endothelial cell counts in the two groups were indistinguishable: 1,675 cells/mm2 in the triple procedure group versus 1,617 cells/mm2 in the PKP/phaco group. This study gives evidence of the outstanding refractive results that PKP with subsequent phacoemulsification and PCIOL implantation can produce.
I believe that PKP with subsequent phacoemulsification and PCIOL placement is the best option for the majority of patients who have corneal disease and concomitant cataract. Nevertheless, the triple procedure should not be abandoned but instead merits consideration for monocular patients and select elderly patients who have profound visual loss due to very dense cataract. The vast majority of patients, however, demand and deserve better visual results than surgeons can deliver with the triple procedure. It is time to raise the bar on the refractive outcomes of patients undergoing surgery for cataract and corneal disease, and PKP with subsequent phacoemulsification and PCIOL implantation allows just that.
Edward J. Holland, MD, is Director of Cornea at the Cincinnati Eye Institute and Professor of Ophthalmology at the University of Cincinnati in Ohio. Dr. Holland may be reached at (859) 331-9000 ext. 3064; firstname.lastname@example.org. Katz HR, Forster RK. Intraocular lens calculation in combined penetrating keratoplasty, cataract extraction and intraocular lens implantation. Ophthalmology. 1985;92:1203-1207.
2. Crawford GJ, Stulting RD, Waring GO III. et al. The triple procedure. Analysis of outcome, refraction, and intraocular lens power calculation. Ophthalmology. 1986;93:817-824.
3. Flowers CW, McLeod SD, McDonnell PJ, et al. Evaluation of intraocular lens power calculation formulas in the triple procedure. J Cataract Refract Surg. 1996;22:116-122.
4. Djalilian AR, George JE, Doughman DJ, Holland EJ. Comparison between the refractive results of combined penetrating keratoplasty/transsclerally sutured posterior chamber lens implantation and the triple procedure. Cornea. 1997;16:319-321.
5. Mattax JB, McCulley JP. The effect of standardized keratoplasty technique on IOL power calculation for the triple procedure. Acta Ophthalmol Suppl. 1989;192:24-29.
6. Taylor DM, Stern AL, McDonald P. The triple procedure: 2 to 10 year follow-up. Trans Am Ophthalmol Soc. 1986;84:221-249.
7. Binder PS. Refractive errors encountered with the triple procedure. Trans New Orleans Acad Ophthalmol. 1987;35:111-120.
8. Meyer RF, Musch DC. Assessment of success and complications of triple procedure surgery. Am J Ophthalmol. 1987;104:233-240.
9. Shimmura S, Ohashi Y, Shiroma H, et al. Corneal opacity and cataract: triple procedure versus secondary approach. Cornea. 2003;22:234-238.