Microkeratome-assisted posterior keratoplasty

Twenty-Two-Year Clinical Outcome of a Case of Endokeratoplasty

PURPOSE

The purpose of this study was to report the 22-year clinical outcome of a patient who underwent endokeratoplasty.

METHODS

To report the clinical outcomes of 37-year-old male who underwent endokeratoplasty for decompensated Fuchs endothelial dystrophy in 1998.

RESULTS

After subsequent cataract surgery and iridoplasty, at 22 years post endokeratoplasty, the Snellen best spectacle-corrected visual acuity is 20/20 (-5.50 sphere -3.00 cylinder at 135 degrees), endothelial cell count is 645 cells/mm 2 , central corneal thickness is 644 μm, and the cornea remains clear with no evidence of graft rejection or failure.

CONCLUSIONS

To the best of our knowledge, this is the longest reported outcome for selective endothelial replacement. The patient undergoing endokeratoplasty can achieve an excellent visual acuity and long-term graft survival.

Cost-Effectiveness Analysis of Descemet's Membrane Endothelial Keratoplasty Versus Descemet's Stripping Endothelial Keratoplasty in the United States

PURPOSE

To determine the cost-effectiveness of Descemet's membrane endothelial keratoplasty (DMEK) compared with Descemet's stripping automated endothelial keratoplasty (DSAEK) in the United States.

DESIGN

Cost-effectiveness analysis in a surgical center in the United States.

PARTICIPANTS

Binocular adult patient undergoing endothelial keratoplasty.

METHODS

A base case of a 70-year-old man undergoing his first endothelial keratoplasty for bilateral Fuchs endothelial dystrophy. The cost-effectiveness of DMEK was compared with DSAEK over a 15-year time horizon. The incidences and costs of complications were derived from PubMed English literature searches, Medicare reimbursements, and average wholesale prices. All costs were discounted 3% per annum and adjusted for inflation to 2018 U.S. dollars. Uncertainty was evaluated using deterministic and probabilistic sensitivity analyses.

MAIN OUTCOME MEASURES

Incremental cost-effectiveness ratios and incremental cost-utility ratios, measured in cost per quality-adjusted life-years (QALYs).

RESULTS

Performing a DMEK instead of a DSAEK generated an extra 0.4 QALYs over a 15-year period. From a societal and third-party payer perspective, DMEK was cost-saving when compared with DSAEK in improving visual acuity in the base case. Probabilistic sensitivity analyses with variations in the costs and rebubble rates revealed that DMEK was cost-saving compared with DSAEK in 38% of iterations and was within a societal willingness-to-pay threshold of $50 000 in 98% of models.

CONCLUSIONS

From the societal and third-party payer perspectives in the United States, DMEK generated greater utilities and was less costly than DSAEK. Therefore, DMEK was the dominant procedure and was cost-saving with respect to DSAEK. The economic model was robust based on sensitivity analyses.

Making the transition from PK to DSEK: experiences during the learning curve

PURPOSE

To report our experiences during the transition from penetrating keratoplasty to Descemet's stripping with endothelial keratoplasty (DSEK).

METHODS

All patients undergoing DSEK during the period of April 2008 to April 2009 were included in this study.

RESULTS

All grafts were attached and clear at both the 6- and 12 -month follow-up examinations. Mean best-corrected visual acuity was 0.6 at 6 months and 0.7 at 12 months for patients without other ocular comorbidity.

CONCLUSION

With adequate attention to detail, DSEK seems to be a safe and successful treatment for corneal endothelial disease, also during the surgeon's learning curve.

A 10.0-mm posterior lamellar graft for bullous keratopathy in a buphthalmic eye

PURPOSE

To report a case of Descemet stripping endothelial keratoplasty (DSEK) with a large posterior lamellar graft for the treatment of bullous keratopathy secondary to congenital glaucoma.

METHODS

Bullous keratopathy secondary to unilateral congenital glaucoma with buphthalmos in a 36-year-old man was treated with DSEK. A Descemet endothelium lamella of 10-mm diameter was excised by descemetorhexis. A regular sclerocorneal donor button of 12-mm diameter was manually split using the Melles technique, and a 10-mm diameter donor graft was punched. The graft was implanted as a folded "Taco" into the anterior chamber using forceps and fixed to the host bed using an intracameral air bubble.

RESULTS

: Immediately after DSEK, the graft showed a small peripheral dehiscence of 1 × 3 mm, which resolved within 2 days. During 30 months of follow-up, the endothelial graft remained well centered, clear, and without any signs of graft rejection. Visual acuity improved from perception of hand movement before operation to 0.2 at 30 months after DSEK. Endothelial cell loss was 33% at 18 months, 44% at 24 months, and 47% at 30 months after operation. Maximum intraocular pressure was 15 mm Hg preoperatively and 16 mm Hg at the last follow-up.

CONCLUSION

DSEK using a corneal graft of 10.0-mm diameter obtained from a normal-sized donor button can be performed safely and effectively in cases of unilateral buphthalmos and secondary corneal decompensation, where a large recipient cornea requires an equivalently sized graft and transplantation of large amounts of donor endothelium.

[Survey of complications in Descemet stripping automated endothelial keratoplasty in 32 eyes]

OBJECTIVE

To report complications during and after Descemet stripping automated endothelial keratoplasty (DSAEK) in 32 eyes at a single academic center with two techniques for delivering the endothelial corneal graft.

PATIENTS AND METHODS

Outcomes from a single center of 32 consecutives cases of DSAEK were analyzed prospectively. In the first 23 patients, the endothelial graft underwent single-fold delivery with forceps, and in the remaining nine patients, the graft was delivered with the Busin glide-based technique. The complications of DSAEK were noted from the intra- and postoperative periods.

RESULTS

Graft detachment was the most common type of complication encountered. In seven of 32 eyes (22%), graft detachments were observed. Three of the 32 eyes (9.5%) were considered to have failed DSAEK, meaning that persistent edema was present after DSAEK. One of the 32 eyes had a late corneal decompensation. Three eyes (9.5%) demonstrated graft rejection. Four eyes with detached grafts were successfully rebubbled after surgery. Two of the 32 eyes (6.2%) underwent repeat DSAEK and three eyes (9.5%) underwent penetrating keratoplasty.

CONCLUSIONS

DSAEK is becoming the preferred method for treating endothelial dysfunction because it maintains the structural integrity of the eye and provides rapid visual recovery with minimal refractive change. However, we experienced some complications. Graft detachment is the most common complication, but postoperative rebubbling allows for graft reattachment in most cases. Other common complications found in this series were graft failure and graft rejection.

Descemet's stripping endothelial keratoplasty: safety and outcomes: a report by the American Academy of Ophthalmology

OBJECTIVE

To review the published literature on safety and outcomes of Descemet's stripping endothelial keratoplasty (DSEK) for the surgical treatment of endothelial diseases of the cornea.

DESIGN

Peer-reviewed literature searches were conducted in PubMed and the Cochrane Library with the most recent search in February 2009. The searches yielded 2118 citations in English-language journals. The abstracts of these articles were reviewed and 131 articles were selected for possible clinical relevance, of which 34 were determined to be relevant to the assessment objectives.

RESULTS

The most common complications from DSEK among reviewed reports included posterior graft dislocations (mean, 14%; range, 0%-82%), followed by endothelial graft rejection (mean, 10%; range, 0%-45%), primary graft failure (mean, 5%; range, 0%-29%), and iatrogenic glaucoma (mean, 3%; range, 0%-15%). Average endothelial cell loss as measured by specular microscopy ranged from 25% to 54%, with an average cell loss of 37% at 6 months, and from 24% to 61%, with an average cell loss of 42% at 12 months. The average best-corrected Snellen visual acuity (mean, 9 months; range, 3-21 months) ranged from 20/34 to 20/66. A review of postoperative refractive results found induced hyperopia ranging from 0.7 to 1.5 diopters (D; mean, 1.1 D), with minimal induced astigmatism ranging from -0.4 to 0.6 D and a mean refractive shift of 0.11 D. A review of graft survival found that clear grafts at 1 year ranged from 55% to 100% (mean, 94%).

CONCLUSIONS

The evidence reviewed is supportive of DSEK being a safe and effective treatment for endothelial diseases of the cornea. In terms of surgical risks, complication rates, graft survival (clarity), visual acuity, and endothelial cell loss, DSEK appears similar to penetrating keratoplasty (PK). It seems to be superior to PK in terms of earlier visual recovery, refractive stability, postoperative refractive outcomes, wound and suture-related complications, and intraoperative and late suprachoroidal hemorrhage risk. The most common complications of DSEK do not appear to be detrimental to the ultimate vision recovery in most cases. Long-term endothelial cell survival and the risk of late endothelial rejection are beyond the scope of this assessment.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Surgical alternatives to penetrating keratoplasty II: endothelial keratoplasty

Penetrating keratoplasty (PK) became the standard of care for optical and tectonic rehabilitation of corneal blindness and visual impairment in the second half of the twentieth century. Posterior corneal disorders or endotheliopathies are the reason for one-third to one-half of all corneal transplants today in the US. Any procedure that replaces the endothelium ideally should accomplish the following results: (1) a smooth surface topography without significant change in astigmatism, (2) a highly predictable corneal power, (3) a healthy donor endothelium that resolves all edema, (4) a tectonically stable globe, safe from injury and infection, and (5) an optically pure cornea. Although PK consistently can achieve results 3 and 5 above, the other goals of stable topography, predictable corneal power and tectonic stability, have remained elusive despite our best efforts at ingenious suturing and trephination techniques. Endothelial keratoplasty (EK) is a new surgical procedure designed to replace diseased corneal endothelium with healthy donor endothelium through either a lamellar corneal flap approach or through limbal scleral incision, leaving the surface of the recipient cornea untouched by surface corneal sutures. This manuscript evaluates the impact and future of EK in ophthalmology.

Early Postoperative Complications of Deep Lamellar Endothelial Keratoplasty

PURPOSE

To report and discuss the early postoperative complications of deep lamellar endothelial keratoplasty (DLEK).

METHODS

The records of the first 44 patients who underwent DLEK by 1 surgeon were reviewed. Complications occurring between the first day and eighth week after surgery were recorded.

RESULTS

In 6 patients (13.6%), the donor disc was floating in the anterior chamber on the first postoperative day and was repositioned with a 30-gauge needle. Fluid was present between the cornea and the disc in 8 patients (18.2%); in 6 of them, the fluid absorbed spontaneously. In 2 patients, the fluid was aspirated 1 month after surgery, but fibrosis developed in the interface. Two patients (4.5%) had persistent corneal edema. In 1 of them, the edema resolved after 2 months, but the other needed penetrating keratoplasty. One patient (2.3%) developed endothelial graft rejection when steroid treatment was discontinued because of exacerbation of preexisting glaucoma. Ten patients (22.7%) had elevated intraocular pressure (IOP) before surgery. The pressure was controlled with topical medication after surgery in 7 patients, 1 patient (mentioned above) suffered graft rejection, 1 patient underwent repeat trabeculectomy, and 1 patient needed insertion of a glaucoma valve. Three patients (6.8%) who did not have glaucoma before surgery developed elevated IOP postoperatively, which was controlled with topical medication.

CONCLUSION

Non-adhesion of the disc and elevated IOP were the most common complications after DLEK. The mechanical preparation of a thinner donor disc and more experience may lead to fewer postoperative complications and their more efficient management.

Evaluation of a new system for obtaining donor lamellar grafts

PURPOSE

To evaluate the performance of a new system for obtaining corneal lamellar grafts of preset sizes. The system consists of the combination of an artificial anterior chamber (MALKS) and an automated microkeratotome (MASYK).

METHODS

A prospective study was performed. Lamellar tissue was obtained with the microkeratotome from 40 human corneoscleral buttons mounted in the artificial anterior chamber. The instrument was set to cut lamellae with a center thickness of 350 microm and a diameter of 10 mm. A new cutting blade for the microkeratotome was used for every 8 cases. Thickness was measured by ultrasound pachymetry. The lamellar diameter was assessed with a micrometric caliper.

RESULTS

The center thickness of the corneal lamellae ranged from 230 to 430 microm (mean, 322 +/- 48 microm; 95% confidence interval [CI], 307-337 microm). The diameter of the stromal ranged from 9.26 to 10.74 mm (mean, 10 +/- 0.27 mm; 95% CI, 9.9-10 mm). There were no cases of perforation or incomplete/irregular lamellae. The interface between the residual stroma and the lamellae was macroscopically smooth. The repetitive use of the same blade up to 8 times did not significantly change these results.

CONCLUSION

The MALKS and MASYK system showed good accuracy in obtaining lamellae of specific thickness and size taken from human corneoscleral buttons. It is a promising instrument for use in deep lamellar keratoplasty. The technique may be useful in obtaining precut lamellar donor tissue for distribution by eye banks.

In Vivo Femtosecond Laser-Assisted Posterior Lamellar Keratoplasty in Rabbits

PURPOSE

To develop a rabbit model for femtosecond laser-assisted posterior lamellar keratoplasty.

METHODS

The femtosecond laser was used to make the posterior corneal lamellar interface and trephine (side) cut in 12 eyes of 11 rabbits. Laser parameters were energy 6.0 to 8.7 (lamellar cut) and 6.0 to 8.8 microJ (trephination cut), spot size 2.4 microm, firing rate 15 kHz, and trephination diameter 6.0 to 7.0 mm. In all eyes, the posterior corneal disc was removed from the eye after laser treatment through a blade incision in the peripheral cornea. The same excised corneal disc was repositioned into the posterior stromal bed to simulate posterior lamellar transplantation. Four eyes of 3 rabbits were enucleated immediately after surgery, and 8 eyes of 8 rabbits were enucleated after a mean follow-up of 17.9 +/- 6.5 weeks. The corneal cut surfaces were examined by light microscopy and scanning electron microscopy.

RESULTS

The femtosecond laser was successful in producing posterior lamellar and trephination cuts in rabbit eyes. The thickness of the posterior corneal discs was 204.3 +/- 21 microm (56.9% of central corneal thickness), and postoperative keratometry was 49.1 +/- 5.8 D. Clinical appearance consistent with corneal ectasia was noted in 3 eyes.

CONCLUSION

The femtosecond laser can make nonmechanical cuts for posterior lamellar keratoplasty with relative ease and reliability in rabbit eyes. A minimum residual anterior corneal thickness may need to be maintained to prevent ectasia.

Histology of Dislocations in Endothelial Keratoplasty (DSEK and DLEK)

PURPOSE

Laboratory studies were performed to evaluate the histologic differences between the recipient bed after deep lamellar endothelial keratoplasty (DLEK) surgery and Descemet's-stripping endothelial keratoplasty (DSEK) surgery. Relevant new surgical strategies to prevent dislocation in DSEK surgery were initiated in our first 100 consecutive clinical cases.

METHODS

Ten pairs of cadaver eyes had a DLEK in 1 eye and a DSEK in the fellow eye, and the posterior stromal surface was analyzed by scanning electron microscopy at x50 magnification. Based on the findings in these cadaver eyes, our DSEK procedure was modified to include surgical roughening in the peripheral recipient bed in 100 consecutive eyes. One hundred percent of these eyes were followed for at least 60 days after surgery to determine the rate of donor dislocation.

RESULTS

In all 10 pairs of cadaver eyes, the DSEK stromal interface showed a smoother surface than DLEK eyes, without the presence of cut stromal fibrils. The DLEK surface was less smooth than the DSEK eyes, but with the presence of uniformly cut fibrils over the entire surface. Subsequent surgical modifications to the DSEK procedure to include scraping and roughening of the recipient peripheral bed in humans resulted in only a 4% (4/100) dislocation rate of the donor tissue into the anterior chamber. One of these 4 dislocated donors was seen on the first postoperative day and was the only primary graft failure in the series. The other 3 cases were fully attached on the first postoperative day with no interface fluid, but they dislocated later on postoperative days 2, 3, and 4.

CONCLUSION

The high rate of dislocation of the donor disc in DSEK may be caused by the absence of recipient stromal fibrils to initially bind to the donor stromal fibrils. Clinical success with a surgical technique of selectively scraping the peripheral recipient bed to promote donor edge adhesion (while leaving the central bed untouched for vision) may aid in the prevention of donor dislocation in DSEK surgery. Reduction of dislocation in DSEK surgery has also been associated with a reduced rate of iatrogenic primary graft failure (PGF) to 1%.

Microkeratome assisted deep lamellar keratoprosthesis

AIMS

To establish a keratoprosthesis (Kpro) surgical technique that maintains an intact superficial corneal layer.

METHODS

A manual microkeratome (Moria LSK-1) was used to create a 130 mum flap of approximately 10 mm diameter in the right eye of Japanese white rabbits. The stoma beneath the flap area was dissected before the removal of a 5.0 mm stromal disc. A 5.0 mm collagen I immobilised poly(vinyl alcohol) (COL-PVA) disc was placed on the exposed posterior stroma close to Descemet's membrane. The flap was repositioned and fixed using 10-0 nylon sutures, which were removed 2 days following surgery. The corneas were followed clinically by slit lamp microscopy and photographs. Rabbits were sacrificed after 6 months, and the transplanted corneas were examined histologically by haematoxylin and eosin staining and immunohistochemistry against vimentin and alpha-smooth muscle actin (alpha-SMA).

RESULTS

The transplanted COL-PVA discs remained transparent throughout the study, with no complications related to the flap or overlying epithelium. The interface between COL-PVA and Descemet's membrane remained clear without signs of opacification caused by scarring or cellular deposition. Pathology revealed the intact COL-PVA polymer in the posterior stroma, with minimal cellular infiltration along the anterior and posterior interfaces. Immunohistology shows vimentin and alpha-SMA staining at levels comparable to lamellar keratoplasty control.

CONCLUSIONS

Microkeratome assisted deep lamellar keratoprosthesis may be a safe technique for the transplantation of artificial hydrogels for therapeutic purposes.

Structural characterization of bioengineered human corneal endothelial cell sheets fabricated on temperature-responsive culture dishes

For the purpose of corneal regenerative medicine, we fabricated human corneal endothelial cell sheets on temperature-responsive dishes, which could be non-invasively harvested as intact, transplantable sheets by simply reducing the culture temperature. Cells demonstrated hexagonal cell shape with numerous microvilli and cilia, and also exhibited abundant cytoplasmic organelles similar to these cells in vivo. Immunofluorescence for type IV collagen and fibronectin revealed that abundant extracellular matrix (ECM) was deposited on the basal surface throughout culture, and the deposited ECM was harvested along with the cell sheets by reducing culture temperature to 20 degrees C. Faint ECM remnants were observed on the dish surfaces after cell sheet detachment. Immunofluorescence for ZO-1 showed that tight junctions were established between cells, and immunoblotting indicated that intact ZO-1 was maintained during cell sheet harvest, while conventional proteolytic cell harvest methods resulted in the degradation of ZO-1. These results suggest that these transplantable corneal endothelial cell sheets can be applied to treat patients with damaged corneas.

A risk score as part of an evidence-based approach to the selection of corneal replacement surgery

PURPOSE

There is currently no standardized methodology that permits preoperative prediction of the surgical technique or drug regimen for corneal grafting most likely to succeed for an individual patient. A score factor related to the chance of successful penetrating keratoplasty (PK) may assist in standardization of graft outcome reporting and evidence-based management.

METHODS

The Risk Score (RS) is based on factors shown to reduce the probability of 1-year survival of conventional PK in increments, using published Australian Corneal Graft Registry data. To asses its validity, Kaplan-Meier survival curves from 156 corneal replacement surgeries, stratified by preoperative RS, were used to derive the probability of survival at 1 year for donor PK, with or without systemic immunosuppression, and for synthetic PK with the AlphaCor artificial cornea. The probability of survival was then plotted against RS for each regimen, producing a family of curves.

RESULTS

The mean RS for immunosuppressed cases was higher than for nonimmunosuppressed cases. The AlphaCor group had the highest scores. AlphaCor survival is little affected by the factors that affect the risk of graft survival, whereas the probability of donor graft survival, immunosuppressed or not, is inversely related to RS.

CONCLUSIONS

This study was designed to test a method that allows objective comparison of outcomes of different methods of corneal replacement for different risk categories. Analysis of this small dataset supports the validity of the concept and suggests that the Risk Score is a useful descriptive statistic. With a sufficient sample size, statistically significant evidence of the optimum management method for an individual patient with a particular risk profile could be determined such that a prospective patient's preoperative RS could be used to assist management decisions. In particular, data allowing separation of different immunosuppression regimes would be useful. Functional outcomes such as visual acuity would be more significant clinically than the survival end point used in this study and the system also could be adapted to different follow-up periods.

Long-term outcome of iron-endocytosing cultured corneal endothelial cell transplantation with magnetic attraction

The long-term efficacy and safety of transplanting iron-endocytosing cultured corneal endothelial cells (CECs) with magnetic attraction were evaluated. Rabbit corneas were subjected to cryo-injury to detach CECs. Cultured rabbit CECs (RCEC) were exposed to spherical iron powder and then injected into the anterior chamber, after which a neogium magnet was fixed on the eyelid for 24 hr to attract the cells to Descemet's membrane (RCEC-iron group, n=4). An RCEC group (cryo-injury and injection of normal cultured RCEC, n=4) and a Cryo group (cryo-injury without injection of RCEC, n=4) served as controls. Intraocular pressure was measured for 12 months after surgery. Corneal findings on slit lamp biomicroscopy, RCEC density, the electro-retinogram (ERG), and residual iron in the ocular tissues were evaluated at final assessment. Intraocular pressure did not increase in any group throughout 12 months of observation. At the final assessment, the average corneal edema score of the RCEC-iron group was significantly lower than that of the RCEC or Cryo groups (p=0.021). The average CEC density of the RCEC-iron group was 2581+/-230 cells mm(-2) (mean+/-SD), whereas no CECs were observed on the inner surface of the central cornea in the RCEC and Cryo groups. No significant differences of the ERG (a- and b-wave amplitudes, and b-wave/a-wave ratio) were detected among the groups. Iron powder was not detected by Berlin blue staining in the ocular tissues of the RCEC-iron group. Apoptotic cells were not observed in the endothelium by terminal transferase-mediated nick-end labeling. Transplanted iron-endocytosing RCEC remained viable for 12 months after surgery. There were no detectable ocular complications after the transplantation of iron-endocytosing cultured RCEC. Magnetic attachment of iron-endocytosing CECs can be an effective and safe method for corneal endothelial repair.

Transplantation of corneal endothelium with Descemet's membrane using a hyroxyethyl methacrylate polymer as a carrier

AIMS

To evaluate the histology and function of Descemet's membrane transplanted with intact endothelium.

METHODS

Japanese white rabbits and human eyebank eyes were used as donors and recipients of Descemet's membrane transplantation. Donor endothelium was hydrodissected by injecting indocyanine green from a limbal incision, and then processed as a corneal scleral button. A 6 mm diameter donor sheet was trephined, and folded in half using a 6 mm diameter polymer as a carrier. Recipient endothelium was also hydrodissected from the limbus using trypan blue to stain the Descemet's membrane. Continuous curvilinear descemetorhexis (CCD) was performed to remove a circular section of the Descemet's membrane using a 27 gauge cystotome. Donor tissue was inserted into the anterior chamber through a 5 mm limbal incision and apposed to the host stroma. Polymers were removed following transplantation. Similar surgical procedures were performed in both rabbits and eyebank eyes. Haematoxylin eosin stains were performed after 28 days in rabbits, and eyebank eyes were fixed immediately following surgery for endothelial cell counts.

RESULTS

Rabbit control eyes demonstrated stromal oedema caused by loss of Descemet's membrane, whereas transplanted eyes had clear corneas. The mean (standard deviation) pachymetry of operated eyes was 376.6 (SD 32.5) mum compared with 389.6 (SD 25.1) mum in the unoperated eye. Mean endothelial density immediately following surgery in eyebank eyes was 2749 (SD 288) cells/mm(2).

CONCLUSIONS

Transplantation of Descemet's membrane by CCD produces a functional graft with an optically clear interface similar to control cornea.

Component Surgery of the Cornea

Penetrating keratoplasty (PKP) has long been the standard procedure for treating irreversible opacification of the cornea from various diseases. The success rate of PKP is high compared with those in other organ transplants because of the low incidence of immunologic rejection. However, once rejection does occur, secondary procedures are inevitably less successful. Cases with vascularized corneas are also prone to undergo rejection, and severe disease causing total destruction of limbal tissue is considered a contraindication for surgery. Recent advances in corneal surgery aim at reducing surgical trauma to the host cornea by replacing only necessary cells and tissue. This approach not only reduces the risk of immunologic rejection but may also yield better refractive results. The various transplantable "components" of the cornea include the epithelium, epithelial stem cells, stroma, and endothelium. Cells from these components can be transplanted as lamellar sections of donor cornea or as sheets using biologic carriers and scaffolds. Procedures such as epithelial sheet transplants using amniotic membrane carriers, deep lamellar keratoplasty, and endothelial lamellar keratoplasty are already in clinical practice. Further refinements in technology will certainly take the limits of corneal surgery to new horizons.

Corneal Endothelial Transplantation

PURPOSE

We present the results of our clinical series replacing posterior stroma and endothelium only by deep lamellar endothelial keratoplasty (DLEK) in patients with corneal endothelial diseases.

METHODS

Through a 9.0-mm superior scleral incision, a deep stromal pocket was created across the cornea. A 7.5-mm posterior lamellar disc of recipient tissue was excised and replaced by same-size donor posterior disc without suture fixation. Three cases were followed for 12 months after DLEK. Best spectacle-corrected visual acuity (BSCVA), endothelial cell density, and corneal thickness were examined.

RESULTS

At 12 months after surgery, all transplants were clear and in position. In the 3 cases, BSCVA at 12 months was 20/200 (hand motion before operation), 20/50 (6/200 before operation), and 20/60 (20/250 before operation), respectively. In one patient, postoperative endothelial cell density was 533 cells/mm(2) with a very thin donor disc. In the other two patients, postoperative endothelial cell density was >2000 cells/mm(2). Corneal thickness (+/-SD) averaged 0.51 +/- 0.06 mm.

CONCLUSIONS

DLEK in the setting of corneal endothelial diseases is an effective surgical procedure without corneal surface incisions and sutures.

Deep lamellar endothelial keratoplasty (DLEK): pursuing the ideal goals of endothelial replacement

Endothelial dysfunction is a leading cause of corneal vision loss and treatment requires surgical replacement with donor endothelium. Standard penetrating keratoplasty (PK) suffers from the inherent problems of surface corneal incisions and sutures and poor wound healing of vertical stromal wounds. This often results in high irregular astigmatism, unpredictable corneal power, and the risk of long-term visual loss from suture-induced vascularization, ulceration, rejection, and late wound rupture. This paper delineates five ideal goals of endothelial replacement, which include: (1) a smooth surface topography without significant change in astigmatism from preoperative to postoperative; (2) a highly predictable and stable corneal power; (3) a healthy donor endothelium that resolves all oedema; (4) a tectonically stable globe, safe from injury and infection; and (5) an optically pure cornea. Deep lamellar endothelial keratoplasty (DLEK) is a surgical method of endothelial replacement that is performed through a limbal scleral incision that leaves the surface of the recipient cornea untouched. The early results of this innovative surgery are discussed and compared to the results of PK in terms of fulfillment of the five ideal goals of endothelial replacement. With further refinement of interface creation, DLEK surgery may be the ideal method for endothelial replacement.

Epithelial ingrowth in the flap–graft interface after microkeratome-assisted posterior penetrating keratoplasty

A 79-year-old woman with pseudophakic bullous keratopathy had microkeratome-assisted posterior keratoplasty for the treatment of clinically significant corneal edema. An island of epithelial ingrowth was noted in the flap-graft interface that was not communicating with the flap periphery. Partial lifting of the anterior corneal flap and removal and irrigation of the epithelial cells were successfully performed. A review of reports of microkeratome-assisted posterior penetrating keratoplasty shows epithelial ingrowth is common after this procedure. The presence of posterior sutures, a central location of the epithelial cells, communication with the periphery, and evidence of stromal melting should prompt immediate surgical intervention.

Magnetic attraction of iron-endocytosed corneal endothelial cells to Descemet's membrane

PURPOSE

To evaluate the feasibility of a novel method of magnetic attraction of iron-endocytosed corneal endothelial cells to Descemet's membrane.

METHODS

Cultured rabbit corneal endothelial cells (RCEC) were exposed to spherical iron powder at various concentration ranging 0-100 micro moll(-1). After 24hr, the cell density and morphology were evaluated. RCEC that had been exposed to spherical iron powder (RCEC-iron), were trypsinized and poured onto a culture dish where a neodium magnet was fixated paracentrally. After 24hr, the cell density was measured at the areas with and without a magnet. Rabbits' corneas were cryo-injuried to detach corneal endothelial cells and 1x10(5)/200 micro l RCEC-iron were injected into the anterior chamber. Neogium magnet was fixed on the lid for 24hr to attract RCEC to Descemet's membrane. Each operated eye was observed up to 2 months after the injury. RCEC group (rabbits with cryo-injury and injection of normal cultured RCEC) and cryo group (rabbits with cryo-injury but without injection of RCEC) served as controls.

RESULTS

The RCEC-iron density on the dish decreased in the medium containing iron powder of 10 micro moll(-1) or more. When RCEC had been exposed to iron powder of between 5 and 10 micro moll(-1), the ratio of RCEC in the field with a magnet to RCEC in the field without a magnet increased. In the RCEC-iron group, the mean corneal thickness gradually decreased and was significantly less than in the other two groups at 2, 4, and 8 weeks after the cell injection. Fluorescein microscopic examination showed a monolayer of DiI-labelled cells on the Descemet's membrane.

CONCLUSION

Magnetic attachment of iron-endocytosed corneal endothelial cells to Descemet's nembrane can be a method of choice for corneal endothelial decompensation.

Replacing the endothelium without corneal surface incisions or sutures: the first United States clinical series using the deep lamellar endothelial keratoplasty procedure

PURPOSE

To report the 6- and 12-month results of the first United States clinical series of deep lamellar endothelial keratoplasty (DLEK) in the treatment of endothelial dysfunction.

DESIGN

Prospective, noncomparative, interventional case series.

PARTICIPANTS

Eight eyes of eight patients with corneal edema from Fuchs' dystrophy and pseudophakia.

METHODS

A 9.0-mm limbal, scleral, partial-depth incision provided access for a deep lamellar corneal pocket dissection. A 7.5- to 8.0-mm posterior lamellar disc of recipient tissue was then excised and replaced through the pocket with a same size donor disc containing healthy endothelium. A temporary air bubble in the anterior chamber was used for donor tissue adherence, and no surface corneal incisions or sutures were necessary.

MAIN OUTCOME MEASURES

Preoperative and postoperative best spectacle-corrected visual acuity (BSCVA), manifest refraction astigmatism, TMS-1 topography, ultrasonic pachymetry, Orbscan topography, and endothelial cell density were evaluated. Intraoperative and postoperative complications are reported.

RESULTS

At 6 and 12 months after surgery, all eight corneas were clear and the grafts were healed in good position. At 6 months, the BSCVA varied between 20/30 and 20/70, the average change in astigmatism from before surgery was +1.13 diopters (D; +/-1.50 D), the average change in corneal power was -0.4 D (+/-1.7 D), the average pachymetry was 648 micro m (+/-134 micro m), and the average endothelial cell count was 2290 cells/mm(2) (+/-372 cells/mm(2)). At 12 months, three of the four eyes reaching this time gate were 20/40 or better, with a change in astigmatism from before surgery of only +0.81 D (+/- 0.55 D), a corneal power change of -1.3 D (+/- 0.4 D), and an endothelial density of 2409 cells/mm(2) (+/- 154 cells/mm(2)). One of the original nine eyes entered into this study required conversion to standard penetrating keratoplasty as a result of a microperforation during recipient pocket dissection and has experienced no ill effects.

CONCLUSIONS

The DLEK procedure, with its absence of corneal surface incisions and sutures, is a safe procedure that preserves the normal corneal topography, minimizes astigmatism and corneal power changes, and provides a healthy donor endothelial cell count and function. If interface optical clarity can be maintained, then this technique offers considerable advantages over penetrating keratoplasty in the treatment of endothelial dysfunction.

New techniques in lamellar keratoplasty

In the past years, several lamellar keratoplasty surgical techniques have been developed, modified or improved in the past years, including microkeratome assisted anterior and posterior lamellar keratoplasty, anterior lamellar keratoplasty using air-dissection or visco-dissection, sutureless posterior lamellar keratoplasty, LASIK for postkeratoplasty astigmatism, and excimer laser assisted keratophakia for keratoconus or to manage complications after LASIK. These procedures may continue to gain interest as alternative procedures for a penetrating keratoplasty in the treatment of various corneal disorders.

New lamellar keratoplasty techniques: posterior keratoplasty and deep lamellar keratoplasty

Posterior keratoplasty is a new surgical technique that may be valuable in treating patients with corneal decompensation secondary to endothelial dysfunction. There are currently two approaches to posterior keratoplasty. In the first approach, a corneal flap is created using a microkeratome (similar to laser in situ keratomileusis flap), and posterior stromal tissue is excised (by trephination or excimer laser keratectomy). In the second approach, a deep stromal pocket is created across the cornea through a superior scleral incision. A custom-made flat trephine is inserted into the pocket to excise a posterior lamellar disc. Preliminary studies have shown the feasibility of performing these techniques in sighted human eyes. Despite potential advantages, further clinical studies are needed to determine whether these techniques reduce interface scarring, astigmatism and graft rejection, improve visual outcomes, or are potentially an alternative for penetrating keratoplasty.