Posterior lamellar keratoplasty (PLK), in which the posterior corneal layers are replaced by donor tissue through a scleral incision, was first reported by Melles et al.1–3 as an alternative to full-thickness penetrating keratoplasty (PKP) for treatment of corneal endothelial disorders, such as Fuchs' dystrophy. Because PLK leaves the anterior corneal surface intact, it is potentially less prone to the major drawbacks of PKP, including induced irregular astigmatism, difficulty in predicting the final visual outcome, suture complications, and long-term risk for wound dehiscence.4–9
With standard PKP, it has been our routine practice to first perform the PKP and then, after suture removal, cataract surgery in those patients with both preexisting endothelial disease and cataracts. In fact, because PKP surgery has become more successful in terms of graft survival,10–12 the biggest limitation may now be unwanted refractive errors producing anisometropia. Cataract surgery has provided the best means of eliminating or lessening large refractive errors after PKP. During cataract surgery, one can correct residual post-PKP astigmatism either with a toric intraocular lens (IOL) or through special orientation and construction of the cataract incision to correct the cylindrical error. On the basis of our experience that favorable visual results are obtained when cataract surgery is performed after PKP, our early PLK cases included some eyes with either early cataracts or clear crystalline lenses.
To our knowledge, there have been no reports either of PLK in phakic eyes or of cataract surgery following PLK. Here we report 4 phakic patients who underwent PLK for treatment of Fuchs' corneal dystrophy. Within 1 year of transplant, each of these patients developed a cataract in the grafted eye. All 4 patients subsequently had cataract surgery and placement of an IOL with no adverse effect on the clarity of the posterior lamellar graft.
Patients and Methods
In this retrospective study, all 47 PLK cases performed by a single surgeon (F.W.P.) at a single tertiary care clinic (Price Vision Group) between June 2001 and December 2002 were reviewed with regard to the patient's lens status at the time of surgery. Case reports are presented for the 4 eyes that were phakic at the time of PLK; these included the first 2 cases in the series.
All PLK surgeries were performed using techniques similar to that described by Melles et al.1–3 In all 4 eyes, a superior scleral tunnel was fashioned, either 8 mm in width if a spatula insertion of the donor was used or 6 mm in width if a taco-style insertion of the donor was used. The anterior chamber was filled with air to allow visualization of the depth of the corneal dissection,2 and then a series of 3 dissection blades (DORC International) were used to make a lamellar dissection at approximately 90% depth across the cornea out to the limbus. The trephine selected for cutting the donor button was used to lightly incise the epithelium of the recipient so that a reference mark was present to judge where to excise the recipient tissue. Trypan blue was used to stain the interface dissection to better visualize the tissue for the next step of excising the recipient button. The anterior chamber was next filled with viscoelastic and 3 scissors (1 specially designed Vannas scissors by ASICO, and 2 specially designed scissors by DORC International) were used to excise the recipient button. Care was taken not to cut the recipient bed any smaller than the trephine mark because a protruding edge on the recipient tissue could prevent an edge of the donor button from seating and create a tract for fluid to get into the interface.
Whereas Melles et al. used whole globes for his donors, we were not able to locate viable donor globes, so we used an artificial anterior chamber previously made by Steinway Instrument Company for the ACS microkeratome. That artificial anterior chamber is no longer manufactured. The donor underwent a similar dissection with the 3 blades and then was placed on a Teflon® cutting block and cut with the designated trephine. It was then placed in the anterior chamber of the recipient either with a spatula, with viscoelastic cushioning the endothelium from the surface of the spatula, or, alternatively, the donor button was folded over on its endothelial side like a taco and placed in the eye using a long Kelman-McPherson forceps. Once in the eye, air was used to push the donor tissue up into the resected bed of the recipient. The incision was closed with interrupted 10-0 nylon sutures. Patients were instructed to apply antibiotic/dexamethasone ointment 4 times a day for 4 days and then to instill 1 drop of prednisolone acetate 1% (Pred Forte®) 4 times a day. Prednisolone acetate 1% dosing was tapered at varying time points, depending on the circumstances, as specified in each case history. (For comparison, we typically taper phakic patients off topical corticosteroids 4 to 8 months after PKP unless an allograft reaction or iritis has developed.13,14)
Cataract surgery was performed by ultrasonic phacoemulsification (Acurus) using only topical anesthesia. A 3.0 mm peripheral temporal clear corneal incision and a smaller stab incision were made. The keratome cut was always made peripheral to the donor tissue to avoid causing wound dehiscence. After injecting intracameral lidocaine 1% and viscoelastic, a divide-and-conquer method was used to remove the nucleus. An IOL was placed using an insertion cartridge. The wounds were self-sealing, and no sutures were used. Patients were instructed to instill ofloxacin 0.3% ophthalmic solution and prednisolone acetate 1% 4 times a day for 1 week. Prednisolone acetate 1% dosing was tapered for 1 month following surgery.
Table 1 summarizes demographic, surgical, and postoperative information for 4 phakic eyes that were treated with PLK. Individual case histories are detailed below. Cases 1 and 2 were the first 2 PLK procedures performed in this series.
A 69-year-old white man with Fuchs' corneal dystrophy had a previous PKP performed in his right eye in 1996. In 2001, the patient elected to have PLK to treat the increasingly hazy vision in his left eye. His best corrected visual acuity (BCVA) before PLK was hazy 20/50 in the left eye with a correction of −2.5 +0.50 × 49. At his follow-up examinations, it was noted that the donor button did not have good apposition to the recipient bed. However, because this was the first case in our series, the situation was monitored until the donor button slipped to the inferior portion of the angle. Three weeks after the initial surgery, the donor button was repositioned as follows: One of the previous scleral incision sutures was removed, a large air bubble was injected into the anterior chamber, the donor button was moved into the proper position on the recipient bed using a 30-gauge needle, and 15 minutes later the air bubble was removed. No contact was made with the lens during this procedure.
Five months after PLK, BCVA in the left eye had declined to 20/200 because of cataract development, so the cataract was removed and an IOL was placed. One month later, the uncorrected vision in the left eye had improved to 20/60−2, and BCVA was 20/50 with a manifest refraction of −0.75 +1.25 × 10. By 3 months after cataract surgery (8 months after PLK), the patient had been tapered off prednisolone acetate 1%. The patient subsequently had a a neodymium:YAG (Nd:YAG) laser capsulotomy. At his final visit 1 week after the capsulotomy (15 months after PLK), the patient's BCVA had improved to 20/30 in the left eye with −0.75 +1.25 × 10 manifest refraction and the posterior graft was clear.
A 69-year-old white man presented with Fuchs' corneal dystrophy, early age-related macular degeneration, and trace nuclear sclerosis in both eyes. These conditions caused difficulty with reading and driving. His BCVA was 20/70 with −2.75 +0.75 × 172 manifest refraction in the right eye and 20/60+1 with −3.75 +1.00 × 7 refraction in the left eye. He complained of increasing problems with glare and haze from the central corneal edema. The patient elected to have PLK in the right eye in June 2001. During follow-up examination, the patient was noted to have developed posterior synechias of the iris to the lens capsule in the superior portion of the lens. One month after surgery, the patient was found to have persistent inflammation in the right eye. A mild cellular reaction was noted in the anterior chamber, but there was no corneal infiltrate or other obvious cause. He was placed on oral (ciprofloxacin) and topical (ofloxacin 0.3%) antibiotics and was maintained on topical prednisolone acetate 1% 4 times a day. The inflammation cleared within a week. Etiology was not determined. This patient was tapered off prednisolone acetate 1% 10 months after PLK.
One year after PLK, the right cornea was clear, but the cataract had progressed to the extent that it appeared to be limiting useful vision. The patient elected to have cataract surgery, and during the procedure the posterior synechias were broken so that the pupil once again dilated normally. A toric IOL was placed in the eye. The left eye was treated with cataract surgery in October 2002, and PLK was performed 4 months later.
At his most recent evaluation, the patient's BCVA was 20/50−1 with −0.50 −0.50 × 85 manifest refraction in the right eye (27 months after PLK). The macular degeneration noted prior to transplant has probably limited the final visual acuity measured in the right eye using the Snellen chart. Nevertheless, the patient was very pleased with the reduction in the glare and haze he previously experienced and he felt that his vision had improved.
A 50-year-old white man presented with Fuchs' corneal dystrophy and difficulty reading, driving, and reading signs. He had also failed the vision test required to obtain his commercial driver's license he needed as a trucker. The BCVA was 20/30−1 with −0.75 +0.50 × 45 manifest refraction in the right eye and 20/40 with −0.5 +0.5 × 65 in the left eye. However, those acuities were measured with Snellen charts in darkened rooms, and he was unable to see well enough to drive because of central corneal edema. A PKP was performed in the left eye in October 2000. In September 2001, PLK was performed in the right eye. This was the seventh case in our PLK series. Three months after PLK, the prednisolone acetate 1% was tapered to twice-a-day dosing for 2 weeks and then tapered to once-a-day dosing in an effort to save the lens. This tapering regimen was accelerated compared with that normally used with our PKP patients. However, it was thought that PLK eyes might be less likely to have immunologic rejection episodes because the PLK procedure involves transplanting only part of the posterior stroma and endothelium, without anterior stroma and epithelium. After 2 weeks on once-a-day dosing with prednisolone acetate 1%, the patient experienced a rejection reaction characterized by keratic precipitates, a rejection line, and stromal edema in the PLK eye. He was treated with prednisolone acetate 1% every hour while awake for the first 4 days, which was then tapered to 8-times-a-day dosing for 3 days, 6-times-a-day dosing for 2 days, and was maintained at 4-times-a-day dosing thereafter. The rejection episode was almost completely resolved 1 week later. Five months after the transplant, a cataract was noted in the PLK eye. The patient had cataract surgery in the right eye with placement of an IOL. Three months after cataract surgery, the patient had an Nd:YAG laser capsulotomy in the right eye.
Twenty-one months after PLK, the patient's uncorrected visual acuity was 20/40 in the right eye. Endothelial cell count was 1680 cells/mm2. In the left eye, which had been treated with a PKP, a rigid contact lens was required for BCVA of 20/20. The patient has been able to obtain his commercial driver's license.
A 59-year-old white woman presented with Fuchs' corneal dystrophy, difficulty driving, and complaints of photophobia. BCVA was 20/80 with +1.00 +0.25 × 157 in the right eye and 20/40 −2 with +0.25 +0.75 × 112 in the left eye. A PLK was performed in the right eye in September 2001. The prednisolone acetate 1% was tapered to a once-a-day dosing 2 months after PLK. Six months after the transplantation, a nuclear sclerotic cataract was removed from the PLK eye and a toric IOL was placed, resulting in a BCVA of 20/30. Prednisolone acetate 1% dosing was increased to 4 times a day following cataract surgery but was tapered back to a once-a-day maintenance level 1 month later. This patient had cataract surgery in her left eye in May 2002 followed by PLK in September 2002.
Twenty-two months after PLK, the right eye experienced a mild rejection episode, characterized by peripheral edema. Prednisolone acetate 1% dosing was increased to 4 times a day, and the rejection episode resolved within a week. Subsequent endothelial cell counts were 540 cells/mm2 in the right eye and 1810 cells/mm2 in the left eye. At her most recent visit, BCVA was 20/25+2 with +0.25 −1.5 × 155 manifest refraction in the right eye (23 months after PLK), and 20/30−1 with +0.25 −0.50 × 147 in the left eye (11 months after PLK).
In this case series, all 4 of the phakic eyes that underwent PLK developed a visually significant cataract within 1 year of transplantation. In phakic eyes there is generally less space in the anterior chamber. This makes the PLK surgery more difficult with an increased risk for lens trauma.
As part of the aging process, the size of the crystalline lens increases, creating some anterior displacement of the iris and shallowing of the anterior chamber. Removal of the crystalline lens allows the iris diaphragm to drop posteriorly, creating space in the anterior chamber. It is much easier to excise the recipient tissue and insert the donor button if there is more space in the anterior chamber. Especially with the taco method of donor insertion, it is helpful to have enough depth to the anterior chamber to allow the folded portion, or underside of the taco, to unfold and rotate over to the other side of the resection bed in the recipient.
There are a number of factors that may have contributed to cataract development in these patients. Unfortunately, older individuals are more likely to have early cataracts, which may be susceptible to rapid progression with even minor trauma. The surgical step that had the greatest potential to traumatize the crystalline lens was excision of the recipient bed with scissors. In particular, performing the cut 180 degrees from the incision was the most challenging step. The injection of air into the anterior chamber may also be traumatic to the crystalline lens, as may be the insertion of the donor button, especially if there is significant back-pressure pushing the lens iris diaphragm anteriorly. All of our cases received retrobulbar injections for their anesthesia, and, in some cases, this can increase the back pressure in the eye, causing further problems with shallowing of the anterior chamber during surgery. These 4 cases were also among the earliest in our PLK series (first, second, seventh, and eighth).
Rejection episodes were experienced in 2 of the 6 PLK eyes described. Like Melles et al.,15 we recommend using a topical immunosuppression regimen after PLK similar to that used after standard PKP.
An important advantage of PLK is that it uses an incision that includes a 1.0 to 3.0 mm lamellar dissection before the anterior chamber is entered, so PLK eyes should be much more resistant to injury than standard PKP eyes. In our experience, PKP eyes can still be ruptured by minor trauma even 15 to 20 years after the surgery. Eyes that had PLK should be much stronger from a structural standpoint.
Posterior lamellar keratoplasty surgery also offers the obvious advantage of not substantially changing the anterior surface of the cornea, so it should not cause large refractive shifts in either sphere or cylinder, which can often be a problem after PKP.1,16,17 However, in our experience, a potential drawback of PLK is the possibility of achieving BCVA of only 20/30 because of interface limitations, at least with hand dissections. Some younger patients, such as our professional truck driver, may have difficulties with BCVA of only 20/30 or 20/40. On the other hand, most of our older patients who have had PLK are very happy to have vision of 20/30 to 20/40 without the glare or haze caused by corneal decompensation or gutta. Also, older patients often prefer not to run the risk for needing to use a hard contact lens to achieve best visual acuity, which may be necessary after PKP,18 as noted in the fellow eye in case 3. In our experience, visual recovery is usually quicker after PLK than after PKP, but it can still be gradual. For example, in case 4, BCVA improved from 20/30 to 20/25+ between the 1-year and 2-year follow-up visits.
Regarding the choice of PLK or PKP, patients with advanced Fuchs' dystrophy or bullous keratopathy need to be evaluated on a case-by-case basis. For example, someone who has macular degeneration in addition to central corneal scarring may benefit from PLK, compared with PKP, because they are likely to get improved peripheral vision with easier follow-up and fewer complications. However, someone with excellent macular function and central corneal scarring may have a better visual result with PKP.
In summary, we think PLK is the most significant advance in corneal transplant surgery in the past 20 years. However, with current techniques, we would recommend it be done only in pseudophakic or aphakic eyes.
1. Melles GRJ, Eggink FAGJ, Lander F, et al. A surgical technique for posterior lamellar keratoplasty. Cornea 1998; 17:618-626
2. Melles GRJ, Rieveld FJR, Beekhuis WH, Binder PS. A technique to visualize corneal incision and lamellar dissection depth during surgery. Cornea 1999; 18:80-86
3. Melles GRJ, Lander F, Nieuwendaal C. Sutureless, posterior lamellar keratoplasty; a case report of a modified technique. Cornea 2002; 21:325-327
4. Binder PS. The effect of suture removal on postkeratoplasty astigmatism. Am J Ophthalmol 1988; 105:637-645
5. Melles GRJ, Binder PS. A comparison of wound healing in sutured and unsutured corneal wounds. Arch Ophthalmol 1990; 108:1460-1469
6. Binder PS. What we have learned about corneal wound healing from refractive surgery. Barraquer Lecture. Refract Corneal Surg 1989; 5:98-120
7. Farley MK, Pettit TH. Traumatic wound dehiscence after penetrating keratoplasty. Am J Ophthalmol 1987; 104:44-49
8. Raber IM, Arentsen JJ, Laibson PR. Traumatic wound dehiscence after penetrating keratoplasty. Arch Ophthalmol 1980; 98:1407-1409
9. Confino J, Brown SI. Bacterial endophthalmitis associated with exposed monofilament sutures following corneal transplantation. Am J Ophthalmol 1985; 99:111-113
10. Thompson RW Jr, Price MO, Bowers PJ, Price FW Jr. Long-term graft survival after penetrating keratoplasty. Ophthalmology 2003; 110:1396-1402
11. Inoue K, Amano S, Oshika T, et al. A 10-year review of penetrating keratoplasty. Jpn J Ophthalmol 2000; 44:139-145
12. Williams KA, Muehlberg SM, Bartlett CM, et al. The Australian Corneal Graft Registry: 1999 Report. Adelaide; Snap Printing, 2000
13. Price FW Jr, Whitson WE, Marks RG. Graft survival in four common groups of patients undergoing penetrating keratoplasty. Ophthalmology 1991; 98:322-328
14. Price MO, Thompson RW Jr, Price FW Jr. Risk factors for various causes of failure in initial corneal grafts. Arch Ophthalmol 2003; 121:1087-1092
15. Melles GRJ, Lander F, van Dooren BTH, et al. Preliminary clinical results of posterior lamellar keratoplasty through a sclerocorneal pocket incision. Ophthalmology 2000; 107:1850-1856; discussion by HE Kaufman, 1857
16. Terry MA, Ousley PJ. Deep lamellar endothelial keratoplasty in the first United States patients; early clinical results. Cornea 2001; 20:239-243; errata, 353
17. Terry MA, Ousley PJ. Endothelial replacement without surface corneal incisions or sutures; topography of the deep lamellar endothelial keratoplasty procedure. Cornea 2001; 20:14-18
18. Price FW Jr, Whitson WE, Marks RG. Progression of visual acuity after penetrating keratoplasty. Ophthalmology 1991; 98:1177-1185