Preparation of donor lamellar tissue for deep lamellar endothelial keratoplasty using a microkeratome and artificial anterior chamber system: endothelial cell loss and predictability of lamellar thickness.

BACKGROUND AND OBJECTIVE: To measure endothelial cell loss and predictability of lamellar thickness after preparing donor tissue for deep keratoplasty with an artificial anterior chamber and microkeratome. MATERIALS AND METHODS: A microkeratome set at a depth of 350 microm and a diameter of 9 mm was used to obtain ten lamellar lenticules from corneoscleral rims mounted in an artificial chamber. A punch trephine then was used to cut the donor tissue 7 mm in diameter. Specular microscopy was performed to evaluate endothelial cell density before the procedure, after cutting with the microkeratome, and after trephination. Pachymetry was performed to determine the predictability of lenticule thickness, before the procedure and after microkeratome incision. RESULTS: Mean post-microkeratome endothelial cell loss was 79 +/- 88 cells/mm2 and post-punch trephination was 85 +/- 94 cells/mm2. This represented a mean percentage loss of 3.2% and 3.5% for the respective steps of this procedure. Nine of the ten lenticules were cut within +/- 75 microm of the intended 350-microm thickness. CONCLUSIONS: Preparing donor lenticules for deep lamellar endothelial keratoplasty with a microkeratome with artificial chamber system caused a relatively small loss of endothelial cells (6.7% of the total) and a reproducible thickness. This may have advantages over manual preparation techniques.     

Precision and accuracy of an artificial anterior chamber system in obtaining corneal lenticules for lamellar keratoplasty.

PURPOSE: To determine the precision and accuracy of an artificial anterior chamber and a manual microkeratome in obtaining corneal lenticules for lamellar keratoplasty. SETTING: Department of Ophthalmology, Cornea, External Diseases and Refractive Surgery Service, University of California Irvine, Irvine, California, USA. METHODS: A lamellar keratectomy was performed in 47 human corneoscleral rims. Three lenticule thicknesses (180, 300, and 360 microm heads) and 3 diameters (7.0, 8.0, and 9.0 mm) were attempted. Diameters and thicknesses were measured by planimetry and pachymetry, respectively. RESULTS: Peripheral lenticule thickness was more likely to be within +/-50 microm of the intended depth in thinner cuts (180 microm, 9/15 corneas, 60%; 300 microm, 6/16 corneas, 40%; 360 microm, 3/12 corneas, 33.3%) (P = .045). Eighty percent (32/40 corneas) were within +/-0.5 mm of the expected diameter. Accuracy was best in the 8.0 mm group, with 47.1% (8/17 corneas) within +/-0.2 mm of the expected diameter. A thickness/diameter correlation was not observed (r(s) < or = 0.28). CONCLUSIONS: The precision and accuracy of this system varied according to the attempted thickness and diameter.     

Therapeutic lamellar keratoplasty with an automated microkeratome

Penetrating keratoplasty (PKP) is the predominant form of corneal transplantation because both manual and automated lamellar keratoplasty are technically difficult and lead to complications such as irregularities and scarring. A microkeratome for laser in situ keratomileusis can be used to overcome these disadvantages. We describe a technique of lamellar keratoplasty performed with an automated microkeratome to treat corneal opacities in the anterior third of the cornea. This easy, accurate technique leads to good visual results and represents a good alternative to PKP in treating anterior corneal opacities.     

Corneal lenticule harvest using a microkeratome and an artificial anterior chamber system at high intrachamber pressure

PURPOSE: To evaluate the safety and accuracy of a manual microkeratome and an artificial anterior chamber used at high intrachamber pressure to harvest corneal lenticules for lamellar keratoplasty. SETTING: Department of Ophthalmology, University of California, Irvine, California, USA. METHODS: Forty-seven human eye-bank corneoscleral rims were mounted on an artificial anterior chamber. A manual microkeratome was used to perform lamellar keratectomy at a mean intrachamber pressure of 95.8 mm hg +/- 4.8 (sd). Two thicknesses (300 microm and 360 microm microkeratome heads) and diameters (8.0 mm and 9.0 mm) were attempted, and the resultant lenticules were analyzed by pachymetry and digital photography. RESULTS: In the 9.0 mm/360 microm group, corneal perforation occurred in 12 of 17 lenticules (71.2%). Except for this group, 24 of 30 corneas (80.0%) showed a less than 0.5 mm deviation from the expected diameter. Neither the horizontal nor the vertical diameter differences were statistically significant (P >.05). The difference between the horizontal and vertical diameters was within +/-0.2 mm in 23 corneas (76.7%). Three (10.0%) corneal beds contained a slightly uneven keratectomy margin. CONCLUSIONS: This system provided accurate and smooth lenticules for lamellar keratoplasty. The precision and accuracy of the obtained corneal lenticules were better than those in previous reports. However, the 9.0 mm diameter/360 microm thickness head with high intrachamber pressure should not be applied in the clinical setting without further testing. In this laboratory study, a minimal corneal thickness of 588 microm was required to avoid perforation.     

Predictability of donor lamellar graft diameter and thickness in an artificial anterior chamber system

PURPOSE: To identify factors affecting the predictability and report results of donor lamellar graft diameter and thickness in an artificial anterior chamber obtained with a microkeratome. METHODS: Lamellar lenticules were obtained from 25 human corneoscleral rims mounted in an artificial anterior chamber. Lenticules measuring 9 mm were attempted at two thicknesses (250 microm and 350 microm heads). Intrachamber pressure of 65 mm Hg was confirmed with Barraquer tonometry. Keratometry, pachymetry, limbal white-to-white, and qualitative mires with the diameter applanation lens were evaluated as possible factors predictive of lenticule diameter and thickness. Diameters and thicknesses were measured with calipers and pachymetry, respectively.RESULTS Ninety-two percent (23/25 lenticules; 14/15 in 250 microm, 9/10 in 350 microm) were +/- 0.25 mm of the intended diameter and 76% (19/25 lenticules; 12/15 in 250 microm, 7/10 in 350 microm) were within +/- 100 microm of the intended thickness. Ovoid applanation mires with the diameter applanation lens represented tissue herniation within the artificial anterior chamber and led to ovoid lenticules (2/25). CONCLUSIONS: Lenticules of 9 mm +/-0.25mm in diameter were highly reproducible with proper corneoscleral rim seating. Intrachamber pressure confirmed with Barraquer tonometry is important in obtaining lenticules of consistent diameter and adequate thickness. Ovoid applanation mires may herald improper corneoscleral rim seating and result in a similarly shaped lenticule. A 2 mm or greater corneoscleral rim is recommended to prevent tissue herniation within the artificial anterior chamber used in this study.     

Double anterior chamber deep lamellar keratoplasty: case report

PURPOSE AND METHODS: We report a case in which, although we planned to perform a penetrating keratoplasty for corneal stromal opacity with normal corneal endothelium, the host's Descemet's membrane became inadvertently detached and the operation resulted in double anterior chamber deep lamellar keratoplasty (DLKP). RESULT: After surgery, the patient's corrected visual acuity was 20/30. CONCLUSION: Double anterior chamber DLKP is safe and valuable.     

Deep anterior lamellar keratoplasty

PURPOSE OF REVIEW: Recent advances in surgical technique have promoted a paradigm shift in the surgical treatment of corneal disease. Penetrating keratoplasty is now being replaced by various types of lamellar techniques that aim to replace damaged tissue only, while maintaining healthy tissue intact. This review focuses on recent advances in deep anterior lamellar keratoplasty. RECENT FINDINGS: The concept of creating a deep lamellar bed for lamellar keratoplasty is not new, but exposing Descemet's membrane was a tedious, time consuming procedure. New techniques that use air and ophthalmic viscosurgical devices to directly expose Descemet's membrane have dramatically reduced surgery time, while improving the safety of performing surgery. The indications for deep anterior lamellar keratoplasty have expanded from keratoconus and hereditary dystrophies, to include severe ocular surface disease and cases following infection and corneal perforation. SUMMARY: Deep anterior lamellar keratoplasty can be considered as the first choice of surgery for a wide range of corneal disease, with bullous keratopathy as the only absolute contraindication.     

Microkeratome-assisted anterior lamellar keratoplasty

Microkeratome-assisted anterior lamellar keratoplasty has emerged as a surgical option for conditions affecting the clarity of the outer 200 mum of the cornea. Herein we describe the outcome of a simple procedure in which the excimer laser can be used to augment deep tissue removal after both recipient bed and donor graft are prepared with the microkeratome. Our noncomparative interventional case series involved 5 eyes of 4 patients with lattice corneal dystrophy who underwent microkeratome-assisted anterior lamellar keratoplasty. Outcome measures include preoperative and postoperative best spectacle-corrected Snellen visual acuity. Visante ocular coherence tomography data are reported for several of the patients.     

Tectonic deep anterior lamellar keratoplasty in impending corneal perforation using cryopreserved cornea

We report a case of tectonic corneal transplantation for impending corneal perforation to preserve anatomic integrity using cryopreserved donor tissue. An 82-year-old woman exhibiting impending corneal perforation suffered from moderate ocular pain in the left eye for one week. After abnormal tissues around the impending perforation area were carefully peeled away using a Crescent blade and Vannas scissors, the patient received tectonic deep anterior lamellar keratoplasty using a cryopreserved cornea stored in Optisol GS® solution at -70℃ for four weeks. At six months after surgery, the cornea remained transparent and restored the normal corneal thickness. There were no complications such as corneal haze or scars, graft rejection, recurrent corneal ulcer, and postoperative rise of intraocular pressure. Cryopreserved donor lamellar tissue is an effective substitute in emergency tectonic lamellar keratoplasty, such as impending corneal perforation and severe necrotic corneal keratitis.     

Triple anterior chamber after full-thickness lamellar keratoplasty for lattice corneal dystrophy.

PURPOSE: To report a patient with lattice corneal dystrophy type I (LCDI) who developed a triple anterior chamber after full-thickness lamellar keratoplasty (LKP). METHODS: A 46-year-old woman underwent a full-thickness LKP in her right eye for visual disturbances caused by LCDI. Her visual acuity was 20/200 OD before surgery. A complete ophthalmic examination, including slit lamp biomicroscopy and optical coherence tomography (OCT), was performed before and after surgery. Molecular genetic analysis was performed on DNA extracted from the peripheral leukocytes. RESULTS: The surgery was performed uneventfully; however, extra spaces posterior to the graft, along with the severe graft edema, were observed to form a triple anterior chamber a few days after surgery. The extra spaces resolved in 3 weeks with no surgical treatment, and her visual acuity improved to 20/20 OD without correction 3 months after surgery. The triple anterior chamber was clearly demonstrated by OCT, but not by slit lamp biomicroscopy. A heterozygous single base-pair transition (CGC to TGC, arginin to cysteine) was detected in codon 124 of the TGFBIgene in the patient. CONCLUSION: The separation of the graft and the host's deep corneal tissue and a Descemet's membrane detachment in the host's cornea caused the triple anterior chamber. The Descemet's membrane detachment demonstrated the weak adhesion of the stroma and the Descemet's membrane, probably resulting from a dysfunction of the TGFBI protein caused by the mutation of the TGFBIgene. OCT is useful for the objective documentation of the posterior corneal region even with severe corneal edema.     

A simple surgical technique for splitting a single donor cornea for performing deep anterior lamellar keratoplasty and Descemet membrane endothelial keratoplasty without using a microkeratome

Purpose:To describe a simple manual surgical technique for splitting a single-donor eye for performing both deep anterior lamellar keratoplasty (DALK) and Descemet membrane endothelial keratoplasty (DMEK) without using a microkeratome.Methods:Twenty-three eyes with anterior stromal pathology and 23 eyes with irreversible endothelial dysfunction were evaluated for keratoplasty at a tertiary eye care referral center. Twenty-three healthy donor corneas were split into two parts. The Descemet’s membrane was stripped and used for DMEK. The stripped stroma was used for DALK. Best-corrected visual acuity (BCVA) of both DALK and DMEK, endothelial cell density, and endothelial cell loss in DMEK were noted at 1-year follow-up, along with any intraoperative or postoperative complications and failures.Results:In the DALK group, mean BCVA improved from 1.264 ± 0.25 log Mar preoperatively to 0.355 ± 0.27 log Mar at 12 months follow-up. There were no complications and failures. In the DMEK group, mean BCVA improved from 1.537 ± 0.61 log Mar preoperatively to 0.592 ± 0.67 log Mar and the mean donor ECD was 3071.66 (range, 2783–3487) cells/mm² preoperatively, which was reduced to 1989.33 (range, 1546–2543) cells/mm² at 12 months follow-up indicating a mean endothelial cell loss of 35%. The failure rate was 21.7%.Conclusion:This study demonstrates that with a single donor corneal tissue, both DALK and DMEK can be performed successfully without any complications. Our technique will help corneal surgeons in all developing countries to cost effectively perform more lamellar surgeries and help in reducing the magnitude of corneal blindness without the need for expensive microkeratomes.     

Deep anterior lamellar keratoplasty for keratoconus

PURPOSE: To investigate surgical outcomes after deep anterior lamellar keratoplasty (DALKP) in eyes with keratoconus. METHODS: Retrospective review of 127 eyes of 118 keratoconus patients who underwent DALKP at King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia between January 1, 1998 and November 30, 2001. The mean age of all patients was 25.9 years (range 11-70 years). The mean follow-up for all patients was 10.9 months (range 4-61 months). Baring of Descemet's membrane (DM) during DALKP was achieved in 47 (37%) eyes; some stroma was left during operation in the remaining 80 (63%) eyes. Snellen visual acuity, intraoperative complications, and postoperative graft status were assessed. RESULTS: At the last follow-up visit, 74% of all eyes were able to achieve a best-corrected visual acuity of 20/50 or better. This level of improvement was more statistically significant with baring of DM (P = 0.005). Intraoperative perforation of DM occurred in 16 (13%) cases and was statistically significant in eyes with deep corneal scars (P = 0.012). However, this perforation did not seem to have an impact on the final visual acuity (P = 0.48). Main graft-related complications included graft-host vascularization (7/127), stromal graft rejection (4/127), graft infection (1/127), and persistent epithelial defect (1/127). CONCLUSIONS: Deep lamellar keratoplasty provides a safer and successful alternative to penetrating keratoplasty for keratoconus patients but remains a challenging procedure. Endothelial graft rejection is absent after DALKP. However, stromal graft rejection, although very rare, does occur.