The evolution of lamellar keratoplasty

Anterior pituitary, sex hormones, and keratoconus: Beyond traditional targets

"The Diseases of the Horny-coat of The Eye", known today as keratoconus, is a progressive, multifactorial, non-inflammatory ectatic corneal disorder that is characterized by steepening (bulging) and thinning of the cornea, irregular astigmatism, myopia, and scarring that can cause devastating vision loss. The significant socioeconomic impact of the disease is immeasurable, as patients with keratoconus can have difficulties securing certain jobs or even joining the military. Despite the introduction of corneal crosslinking and improvements in scleral contact lens designs, corneal transplants remain the main surgical intervention for treating keratoconus refractory to medical therapy and visual rehabilitation. To-date, the etiology and pathogenesis of keratoconus remains unclear. Research studies have increased exponentially over the years, highlighting the clinical significance and international interest in this disease. Hormonal imbalances have been linked to keratoconus, both clinically and experimentally, with both sexes affected. However, it is unclear how (molecular/cellular signaling) or when (age/disease stage(s)) those hormones affect the keratoconic cornea. Previous studies have categorized the human cornea as an extragonadal tissue, showing modulation of the gonadotropins, specifically luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Studies herein provide new data (both in vitro and in vivo) to further delineate the role of hormones/gonadotropins in the keratoconus pathobiology, and propose the existence of a new axis named the Hypothalamic-Pituitary-Adrenal-Corneal (HPAC) axis.

Comparative Study of Long-term Graft Survival Between Penetrating Keratoplasty and Deep Anterior Lamellar Keratoplasty

PURPOSE

Endothelial failure and immunological graft rejection remain long-term complications leading to late graft failure in penetrating keratoplasty (PK). Deep anterior lamellar keratoplasty (DALK) has emerged as a viable alternative that enables preservation of the host's endothelial cells to eliminate risks of endothelial rejection and failure. The aim of this study was to compare long-term graft survival between PK and DALK.

DESIGN

Retrospective clinical cohort study.

METHODS

All consecutive primary grafts of DALKs (n = 362) and PKs (n = 307) performed for optical indications in a tertiary eye center from the ongoing, prospective Singapore Corneal Transplant Study. Ten-year graft survival outcomes were compared. Cases in which endothelial pathologies were diagnosed were excluded, as DALK was not performed for such cases. Main outcome measurements were mean graft survival rate.

RESULTS

The survival rate for PK was 94.4%, 80.4%, and 72.0% at 1, 5, and 10 years, respectively; and 95.8%, 93.9%, and 93.9% at 1, 5, and 10 years, respectively, for DALK (P = .001). Patients who underwent PK developed more complications of glaucoma (29.3% vs. 11.6%, respectively; P < .001), allograft rejection (16.6% vs. 1.7%, respectively; P < .001), epithelial problems (10.4% vs. 5.5%, respectively; P = .018), and nonimmunological failure (7.8% vs. 1.9%, respectively; P < .001), compared to DALK. Rates of graft failure attributable to rejection (36.7% vs. 5.9%, respectively; P = .015) and endothelial failure (36.7% vs. 5.9%, respectively; P = .015) were lower in DALK.

CONCLUSIONS

The 10-year graft survival for primary DALK was superior to that for PK for corneal pathologies with functional endothelium. Primary DALK resulted in fewer post-operative complications and lower rates of graft rejection and failure. This study strengthens the case in favor of performing DALK over PK when possible.

Routine Referral by Urologists Increase Opportunities for Corneal Donation

BACKGROUND

The levels of corneal donation are insufficient to meet the demand for corneal transplantation in Japan. To overcome this problem, we started to routinely mention the possibility of corneal donation to the families of patients who died in our hospital's Urology Department in February 2008. In this study, we evaluated the effectiveness of this approach.

METHODS

We retrospectively reviewed the medical records of the patients who died in the Department of Urology, St. Marianna University School of Medicine Hospital, and analyzed the patients' characteristics and information about corneal donation.

RESULTS

In total, 211 patients died in our department between February 2008 and March 2017, and 155 patients were medically suitable corneal donors. We mentioned the possibility of corneal donation to 129 (83.2%) families, and 29 (18.7%) families agreed. Three families subsequently withdrew their consent. Finally, 26 (16.8%) of the families that were approached about corneal donation by urologists agreed to donate their relatives' corneas. Another 2 families voluntarily offered to donate their relatives' corneas. Thus, 28 (18.1%) of 155 medically suitable donors donated their corneas for transplantation. Twenty-six (92.8%) donors were 60 years or older and all donors were affected with malignant genitourinary tumors. Fifty-four (96.4%) corneas were successfully transplanted into recipients.

CONCLUSIONS

Even elderly patients who die of solid carcinoma can be an important source of corneal donors. In this study, we showed that routine referral by urologists increased corneal donation. If this approach were adopted by other departments, it might further increase the number of corneal donations.

Deep anterior lamellar keratoplasty versus penetrating keratoplasty in corneas showing a high or low graft rejection risk

PURPOSE

To compare visual, topographic and topometric outcomes in patients subjected to deep anterior lamellar keratoplasty or penetrating keratoplasty showing a high or low risk of graft rejection.

SETTING

Complejo Hospitalario La Mancha Centro, Ciudad Real, Spain.

MATERIALS AND METHODS

Data were reviewed for consecutive patients with a corneal stroma disease undergoing deep anterior lamellar keratoplasty or penetrating keratoplasty over the period 2009-2015 at our centre by the same surgeon. The outcome measures examined were 2-year follow-up best-corrected visual acuity, refractive error, topographic astigmatism, intraocular pressure, endothelial cell density and central corneal thickness.

RESULTS

Of 115 eyes enrolled, 46 underwent deep anterior lamellar keratoplasty (15 low risk, 31 high risk) and 69 penetrating keratoplasty (23 low risk, 46 high risk). Mean postoperative best-corrected visual acuity (logMAR) in the low- and high-risk groups, respectively, were 0.31 and 0.26 for deep anterior lamellar keratoplasty (p = 0.32) and 0.40 and 0.51 for penetrating keratoplasty (p = 0.28). The values for the high-risk deep anterior lamellar keratoplasty versus high-risk penetrating keratoplasty patients were 0.26 and 0.51, respectively (p = 0.004). Mean postoperative spherical equivalents were -2.60 D for low-risk deep anterior lamellar keratoplasty versus -2.29 D for high-risk deep anterior lamellar keratoplasty (p = 0.19), and -0.41 D for low-risk penetrating keratoplasty versus -0.13 D for high-risk penetrating keratoplasty (p = 0.51).

CONCLUSION

Final best-corrected visual acuity and visual acuity gains were better for deep anterior lamellar keratoplasty, mainly in corneas with a high rejection risk. Despite a better corneal thickness recorded in the deep anterior lamellar keratoplasty group, the other variables examined were comparable. Deep anterior lamellar keratoplasty emerged as an effective alternative to penetrating keratoplasty for patients with a disease affecting the corneal stroma.

Cataract surgery after deep anterior lamellar keratoplasty and penetrating keratoplasty in age- and disease-matched eyes

PURPOSE

To assess the efficacy and safety of cataract surgery after deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PKP).

SETTING

Tokyo Dental College Ichikawa General Hospital, Chiba, Japan.

DESIGN

Retrospective case series.

METHODS

Age-matched and disease-matched eyes that had phacoemulsification and intraocular lens insertion after DALK or PKP were studied. Graft clarity was assessed at the final follow-up. The difference in the endothelial cell density (ECD), corrected distance visual acuity (CDVA), spherical equivalence, and refractive error between the expected values and values 1, 3, 6, and 12 months after cataract surgery were compared between the 2 groups.

RESULTS

Indications for keratoplasty were corneal stromal scar (22 eyes), lattice dystrophy (2 eyes), keratoconus (2 eyes), and postherpetic keratitis (4 eyes). All 30 eyes in each group had successful cataract surgery after keratoplasty. Graft clarity rates were 90.0% and 80.0% in the DALK group and PKP group, respectively (P = .47). The decrease in ECD at 12 months was significantly greater in the PKP group than in the DALK group (8.7% [SD] ± 21.7% versus 26.3% ± 27.8%) (P = .043). The CDVA was significantly improved in both groups. At 1 month, the mean refractive error was -0.5 diopter (D) ± 2.4 (SD) in the DALK and -0.4 ± 1.9 D in the PKP groups and remained stable thereafter.

CONCLUSIONS

Cataract surgery was successfully performed in eyes that had DALK or PKP, providing excellent visual and refractive outcomes. In cases of combined cataract and corneal pathology, and in the absence of endothelial involvement, DALK followed by cataract surgery might cause less endothelial damage.

Use of glycerol-preserved corneas for corneal transplants

Purpose:

This study was carried out to see the results of glycerol-preserved cornea (GPC) in emergency situation when fresh corneal tissue was not available. The aim was to study the outcome of corneal transplantation using GPC.

Methods:

This was a retrospective study. The medical records of all the patients were reviewed, who underwent keratoplasty using “GPC” during the period from October 2011 to December 2015. The indication of keratoplasty, duration of preservation of the GPC, and its outcome were analyzed. Descriptive statistics were applied.

Results:

Out of the 222 penetrating keratoplasty (PKP) performed over the study period, the GPC was used in 34 patients (males = 31, 91.2%) aged 15–74 years. Therapeutic keratoplasty was performed in all cases in this cohort except one in which tectonic keratoplasty was done. The primary indication of PKP (91.2%) was infectious keratitis. Of these, 20 (64.5%) patients presented with perforated corneal ulcers. Post-PKP, ocular anatomy was preserved in 91.2%, and visual acuity of perception of light positive and accurate projection of rays in all the quadrants was obtained in 76.5% cases. Complications included glaucoma (n = 12, 35.1%), phthisis bulbi (n = 2, 5.9%), and graft reinfection and endophthalmitis after PKP (n = 1, 2.9%). The secondary procedure post-GPC and PKP were trabeculectomy with mitomycin C (n = 7, 58.3%) in patients not controlled on topical antiglaucoma medication. Optical keratoplasty was performed in (n = 3) 8.8% patients and triple procedure in (n = 2) 5.8% patients with good visual acuity postprocedure.

Conclusions:

Acellular GPCs are useful in emergency keratoplasty to avoid loss of vision and can save the eye.

Corneal Biomechanical Properties After Penetrating Keratoplasty or Deep Anterior Lamellar Keratoplasty Using the Ocular Response Analyzer: A Meta-Analysis

PURPOSE

To evaluate the corneal biomechanical properties of patients who have undergone penetrating keratoplasty (PK) or deep anterior lamellar keratoplasty (DALK) using the ocular response analyzer.

METHODS

Stata 13.0 SE was used for this meta-analysis. Studies in the literature that focused on corneal hysteresis (CH) or corneal resistance factor (CRF) after PK or DALK were retrieved by searching PubMed, Embase, Ovid, and Cochrane databases. We present the results as weighted mean difference (WMD) with a corresponding 95% confidence interval (CI).

RESULTS

Eight studies with a total of 750 eyes were included in the post-PK versus control group, and 4 studies with a total of 218 eyes were included in the post-DALK versus control group. The pooled results showed that CH and CRF were significantly reduced (P < 0.00001) for patients who have undergone PK (WMD = -1.16, 95% CI: -1.73 to -0.60 and WMD = -1.00, 95% CI: -1.61 to -0.40). No significant differences were found in both CH and CRF for patients who have undergone DALK (WMD = -0.27, 95% CI: -0.64 to -0.09 and WMD = -0.15, 95% CI: -0.53 to 0.23).

CONCLUSIONS

This meta-analysis suggested that both CH and CRF had better recovery after corneal transplantation with DALK than PK.

[Update: Deep anterior lamellar keratoplasty (DALK) for keratoconus. When, how and why]

BACKGROUND

The treatment of keratoconus has been significantly expanded in recent years. In addition to the previous options for correction by fitting hard contact lenses and penetrating keratoplasty (PK), corneal cross-linking and lamellar transplantation techniques have been added.

OBJECTIVE

The aim of this review article is to highlight currently available options for minimization of complications and standardization of deep anterior lamellar keratoplasty (DALK) for keratoconus.

MATERIAL AND METHODS

This article summarizes our own data and gives a review of the literature in PubMed.

RESULTS

Performing DALK can provide keratoconus patients with corneal grafts with considerably longer graft survival and a reduced risk of complications.

CONCLUSION

The DALK procedure provides numerous advantages over PK, especially the reduced intraoperative opening of the eye, which thus reduces the risk of serious intraoperative complications. A further benefit is the complete absence of postoperative endothelial immune reactions as the recipient's endothelium remains untouched. The absence of endothelial immune reactions is especially advantageous for young patients with keratoconus and patients with an increased risk of graft rejection, e.g. in atopic dermatitis; however, there are also typical complications of DALK that do not occur during PK. The outlined strategies for standardization of DALK and avoidance of intraoperative and postoperative complications should make DALK safer and more reproducible and lead to possible establishment as a standard procedure in keratokonus.

An Analysis of Factors Influencing Quality of Vision After Big-Bubble Deep Anterior Lamellar Keratoplasty in Keratoconus

PURPOSE

To identify causes of reduced visual acuity and contrast sensitivity after big-bubble deep anterior lamellar keratoplasty (DALK) in keratoconus.

DESIGN

Prospective interventional case series.

METHODS

This study included 36 eyes in 36 patients with keratoconus who underwent DALK using the big-bubble technique. A bare Descemet membrane was achieved in all cases. Univariate analyses and multiple linear regression were used to investigate recipient-, donor-, and postoperative-related variables capable of influencing the postoperative quality of vision, including best spectacle-corrected visual acuity (BSCVA) and contrast sensitivity.

RESULTS

The mean patient age was 27.7 ± 6.9 years, and the patients were followed for 24.6 ± 15.1 months postoperatively. The mean postoperative BSCVA was 0.17 ± 0.09 logMAR. Postoperative BSCVA ≥20/25 was achieved in 14 eyes (38.9%), whereas a BSCVA of 20/30, 20/40, or 20/50 was observed in 15 eyes (41.7%), 6 eyes (16.6%), and 1 eye (2.8%), respectively. Preoperative vitreous length was significantly associated with postoperative BSCVA (β = 0.02, P = .03). Donor-recipient interface reflectivity significantly influenced scotopic (β = -0.002, P = .04) and photopic (β = -0.003, P = .02) contrast sensitivity. The root mean square of tetrafoil was significantly negatively associated with scotopic (β = -0.25, P = .01) and photopic (β = -0.23, P = .04) contrast sensitivity. Recipient age, keratoconus severity, donor-related variables, recipient trephination size, and graft and recipient bed thickness were not significantly associated with postoperative visual acuity or contrast sensitivity.

CONCLUSION

Large vitreous length, higher-order aberrations, and surgical interface haze may contribute to poor visual outcomes after big-bubble DALK in keratoconus.

Long-term preservation of donor corneas in glycerol for keratoplasty: exploring new protocols

AIM

To evaluate the role of temperature and adjunctive dehydration in better long-term preservation of human corneas when preserved and stored in glycerol.

METHODS

Different preservation temperatures and effects of adding silica gel in glycerol-preserved corneal tissues were evaluated. Human corneal tissues not suitable for optical keratoplasty initially preserved in McCarey-Kaufman medium were transferred to glycerol and stored at four different temperatures for 3 months as follows: tissues in anhydrous glycerol with and without silica gel at -80°C, -20°C, 4°C and at room temperature (RT). Parameters evaluated included microbial sterility, thickness (Digimatic micrometer), transparency (slit lamp examination, UV-Vis spectrophotometer), mechanical strength (Instron 5848 Microtester), tissue integrity (H&E staining), antigenicity (immunohistochemistry) and ultrastructure of collagen (transmission electron microscopy, TEM).

RESULTS

Microbial test after 3 months of glycerol preservation confirmed sterility of the tissues. The thickness increased in corneas preserved at RT with and without silica gel (p<0.001). RT corneas had the lowest transparency and tensile strength. Tissues in anhydrous glycerol stored with and without silica gel at -80°C were the most transparent (p<0.001) and had the highest tensile strength (p<0.001). Tissue integrity was maintained and expression of Human Leukocyte Antigen D related (HLA-DR) was less in glycerol-preserved corneas at -80°C. TEM studies indicated that parallel alignment of stromal collagen was disrupted at RT-preserved corneas.

CONCLUSIONS

Corneal tissue preserved at -80°C was the best method for preservation as it maintained the sterility, thickness, optical transparency, mechanical strength and ultrastructural features.

Effect of Rho-kinase Inhibitor, Y27632, on Porcine Corneal Endothelial Cell Culture, Inflammation and Immune Regulation

PURPOSE

To investigate the effect of the Rho-kinase inhibitor, Y27632, on pig corneal endothelial cell (pCEC) culture, and on inflammation and immune regulation of the responses of human cells to pCECs.

METHODS

pCECs were cultured with/without Y27632 to assess cell proliferation and in vitro wound healing assay. The level of MCP-1 and VEGF in pCECs stimulated with human TNF-α were measured. Proliferation of human PBMCs stimulated with pCECs, and cytokine production in human T cells, and monocyte migration after stimulation were investigated.

RESULTS

Y27632 promoted pCEC proliferation, prevented pCEC death, and enhanced in vitro wound healing. After stimulation, there were significantly lower levels of MCP-1 and VEGF measured in pCECs cultured with Y27632, and significantly reduced human PBMC proliferation, cytokine production, and monocyte migration.

CONCLUSIONS

The application of the Rho-kinase inhibitor will be beneficial when culturing pCECs, and may provide a novel therapy to reduce inflammation after corneal xenotransplantation.

Comparative study of keratoconus between Anwar's deep anterior lamellar keratoplasty versus converted penetrating keratoplasty

OBJECTIVE

To compare outcomes between penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK) in patients with keratoconus.

DESIGN

Retrospective cohort study.

METHODS

Data of 90 DALK and 49 procedures from conversion to PK, performed by a single surgeon (R.D.) from 2006 to 2011 were analysed. Outcomes on corrected distance visual acuity (BCVA), astigmatism, time to first refraction, pachymetry, endothelial count cell, and postoperative complications were compared between these groups.

RESULTS

The mean age of the patients who underwent DALK and PK was 28.2 and 31.7 years, respectively (P=.17). The mean follow up for DALK and for the PK group was 14.7 and 19.4 months, respectively (P=.13). There was no significant difference between PK and DALK groups in the mean postoperative for: BCVA (LogMAR) (0.17 vs. 0.17; P=.59); refractive astigmatism (-3.19 vs.-3.01 diopters; P=.65), and time for the first subjective refraction (60.5 versus 68 days; P=.50). Main postoperative complications were 8% of endothelial rejection in PK group and 10% of deep stromal vascularization in DALK group.

CONCLUSIONS

The only differences in postoperative results between groups were stromal neovascularization in DALK group and endothelial rejection in PK group. DALK should be considered as the first option when keratoplasty is indicated in keratoconus.

Comparison of Descemet-On Versus Descemet-Off Deep Anterior Lamellar Keratoplasty in Keratoconus Patients: A Randomized Trial

PURPOSE

To compare the visual outcomes of Descemet membrane (DM)-on and DM-off after deep anterior lamellar keratoplasty (DALK) using the big-bubble (BB) technique in keratoconus patients.

METHODS

In this prospective trial, keratoconic eyes undergoing DALK procedures with the BB technique were randomized into 2 groups: a donor cornea without DM (group 1; 29 eyes) or with DM (group 2; 30 eyes). These groups were compared with respect to best-corrected visual acuity and contrast sensitivity while wearing gas permeable contact lenses and also endothelial cell counts.

RESULTS

There were no statistically significant differences between the 2 groups with regard to best-corrected visual acuity and contrast sensitivity using gas permeable contact lenses as well as endothelial cell counts at 3, 6, and 12 months. After 1 year, the mean (±SD) postoperative visual acuity CL (with contact lenses) was 0.05 (±0.01) in the DM-off group and 0.05 (±0.01) in the DM-on group (P = 0.956). Mean postoperative endothelial cell counts were 2425.0 (±123.7) and 2306.7 (79.9), respectively (P = 0.443), and corneal thicknesses were 527.9 (58.3) and 556.6 (47.3), respectively (P = 0.150). During the follow-up period, very few complications occurred and neither group had a predominance of adverse events at 3, 6, 12, or 24 months.

CONCLUSIONS

In conclusion, DALK procedures using the BB technique for keratoconus with DM-on or DM-off presented no significant differences regarding the visual outcomes or endothelial cell counts.

Efficacy and safety of deep anterior lamellar keratoplasty vs. penetrating keratoplasty for keratoconus: a meta-analysis

Purpose

To evaluate difference in therapeutic outcomes between deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PKP) for the clinical treatment of keratoconus.

Methods

A comprehensive search was conducted in Pubmed, EMBASE, Cochrane Library, and Web of science. Eligible studies should include at least one of the following factors: best corrected visual acuity (BCVA), postoperative spherical equivalent (SE), postoperative astigmatism and endothelial cell count (ECC), central corneal thickness (CCT), graft rejection and graft failure, of which BCVA, graft rejection and graft failure were used as the primary outcome measures, and postoperative SE, astigmatism, CCT and ECC as the secondary outcome measures. Given the lack of randomized clinical trials (RCTs), cohort studies and prospective studies were considered eligible.

Results

Sixteen clinical trials involving 6625 eyes were included in this review, including 1185 eyes in DALK group, and 5440 eyes in PKP group. The outcomes were analyzed using Cochrane Review Manager (RevMan) version 5.0 software. The postoperative BCVA in DALK group was significantly better than that in PKP group (OR = 0.48; 95%CI 0.39 to 0.60; p<0.001). There were fewer cases of graft rejection in DALK group than those in PKP group (OR = 0.28; 95%CI 0.15 to 0.50; p<0.001). Nevertheless the rate of graft failure was similar between DALK and PKP groups (OR = 1.05; 95%CI 0.81 to 1.36; p = 0.73). There were no significant differences in the secondary outcomes of SE (p = 0.70), astigmatism (p = 0.14) and CCT (p = 0.58) between DALK and PKP groups. And ECC in DALK group was significantly higher than PKP group (p<0.001). The postoperative complications, high intraocular pressure (high-IOP) and cataract were analyzed, fewer cases of complications occurred in DALK group than those in PKP group (high-IOP, OR 0.22, 95% CI 0.11–0.44, P<0.001) (cataract, OR 0.22; 95% CI 0.08–0.61, P = 0.004). And no cases of expulsive hemorrhage and endophthalmitis were reported.

Conclusion

The visual outcomes for DALK were not equivalent to PKP. The rate of graft failure was similar between DALK and PKP. Fewer postoperative complications occurred in DALK group, indicating that compared with PKP, DALK has lower efficacy but higher safety.

[Corneal transplantation in keratoconus: penetrating keratoplasty versus deep anterior lamellar keratoplasty with Melles technique]

OBJECTIVES

To evaluate the effectiveness of deep anterior lamellar keratoplasty (DALK) using Melles technique (technique B) in patients with advanced keratoconus versus a classic technique, penetrating keratoplasty (technique A).

METHODOLOGY

Retrospective descriptive comparative study between technique A and technique B in homogeneous groups.

RESULTS

Best corrected visual acuity (Snellen test decimal scale) was 0.77±0.32 for group A and 0.62±0.29 for group B, with no statistically significant differences. The mean spherical final refraction in group A was 1.73±5.1 diopters, and the mean spherical equivalent was -3.92±5.1. Technique B group gave values -2.67±4.02 diopters and -4.55±4.08 diopters, respectively, with no statistically significant differences. The residual cylinder after removal of the sutures was 4.47±2.47 diopters for group A and 3.77±1.63 for group B, with no statistically significant differences.

CONCLUSION

No statistically significant differences were found for any of the studied variables when comparing both groups using the t -test for independent samples. More studies on the homogeneity and residual stromal bed thickness could provide the key to determine whether this technique is closer to the visual acuity of penetrating keratoplasty or DALK by a descemet technique.

Effect of donor graft quality on clinical outcomes after deep anterior lamellar keratoplasty

PURPOSE

The aim of this study was to determine the effect of donor features, including age, death-to-preservation time, preservation-to-surgery time, graft rating, and endothelial cell features, on visual and refractive outcomes and complications occurring after deep anterior lamellar keratoplasty (DALK) in patients with keratoconus.

METHODS

In this retrospective study, 290 consecutive keratoconic eyes underwent DALK using donor corneas of different qualities, ranging from fair to excellent. Donor corneas were stored in intermediate-term storage medium. Donor data included age and sex, death-to-preservation time, preservation-to-surgery time, epithelial and stromal status, endothelial cell density and morphology, and graft rating. Postoperative outcomes included visual acuity, refractive error, epithelial problems, suture-related complications, graft rejection, and graft transparency. A multivariate regression analysis was used to assess the correlation between donor characteristics and postoperative outcomes.

RESULTS

Mean donor and recipient ages were 33.4 ± 13.1 and 27.7 ± 8.0 years, respectively. The mean follow-up period was 38.2 ± 20.2 months. The presence of epithelial defects on postoperative day 1 had a significant correlation with donor epithelial sloughing (R = 0.26, P < 0.001), preservation-to-surgery time (R = 0.21, P = 0.001), and graft rating (R = -0.17, P = 0.004). Graft stromal edema on postoperative day 1 was significantly correlated with donor epithelial sloughing (R = 0.31, P < 0.001), preservation-to-surgery time (R = 0.24, P < 0.001), and graft rating (R = -0.28, P < 0.001). Suture-related complications, graft rejection episodes, graft clarity, visual acuity, and refractive outcomes at the final follow-up examination were found to have no correlations with any donor factors.

CONCLUSIONS

The use of low-quality donors for DALK increased the rate of epithelial defects and stromal edema immediately postoperatively. However, the donor features had no influence on visual and refractive outcomes and complications.

Peripheral deep anterior lamellar keratoplasty using a cryopreserved donor cornea for Terrien's marginal degeneration

OBJECTIVE

To evaluate the clinical efficacy of peripheral deep anterior lamellar keratoplasty (DALK) using a cryopreserved donor cornea for Terrien's marginal degeneration (TMD).

METHODS

Thirty-one eyes of 27 patients with TMD underwent peripheral DALK using cryopreserved donor corneas. According to the distance between the inner edge of the lesion and the limbus, a ring-shaped or D-shaped DALK was performed. All grafts were stored at -20 °C. Cryopreserved corneoscleral rims were prepared for ring-shaped grafts and cryopreserved whole eyeballs were prepared for D-shaped grafts. The general conditions, intraoperative performance, postoperative corneal reconstruction, astigmatism, best corrected visual acuity (BCVA), and various complications were analyzed.

RESULTS

Ring-shaped DALK was performed in 28 eyes and D-shaped DALK was performed in 3 eyes. Postoperative follow-up time was (28.4±24.8) months. There was evidence of inflammation before surgery in 12 eyes (38.7%) and intraoperative perforation occurred in 13 eyes (41.9%). The corneal structures of all eyes were reconstructed. Postoperative astigmatism and BCVA showed improvement (both P=0.00) except for cases that underwent D-shaped DALK. Ten eyes (32.2%) developed transient ocular hypertension and one eye (3.2%) developed secondary glaucoma. No primary disease recurrence or corneal allograft rejection was observed.

CONCLUSIONS

Peripheral DALK for TMD using cryopreserved donor tissue is an effective technique that eliminates rejection and extends the use of donor eyes. Inflammatory history or intraoperative perforation has no adverse effect on graft recovery. However, D-shaped DALK did not achieve good visual outcomes.

Distribution of non-gal antigens in pig cornea: relevance to corneal xenotransplantation

PURPOSE

The aim of this study was to investigate the distribution of antigens other than galactose-α-1,3-galactose (Gal) (non-Gal) recognized by human and rhesus monkey serum antibodies in the α-1,3-galactosyltransferase gene-knockout (GTKO) pig cornea.

METHODS

The distribution of non-Gal, specifically N-glycolylneuraminic acid (NeuGc), in the corneas from wild-type (WT) and GTKO pigs was identified. Corneal sections from WT and GTKO pigs were incubated with human or rhesus monkey serum to determine immunoglobulin (Ig)M and IgG binding to corneal tissue by means of fluorescent microscopy.

RESULTS

Strong expression of NeuGc was found in all layers of both WT and GTKO pig corneas. In both humans and monkeys, antibody binding (IgG > IgM) to GTKO was found to be weaker than that to entire WT pig corneas, but in both, most antibody binding, especially IgG, was to the epithelium. There was weak diffuse antibody binding, especially of IgG, to the corneal stroma, suggesting binding to antigens expressed on collagen. There was no or minimal binding of IgM/IgG to the corneal endothelium.

CONCLUSIONS

Although the cornea is avascular, antibodies in primate serum can bind to pig antigens, especially on epithelial cells and stromal collagen. Although the binding to entire GTKO corneas was weaker than that to WT corneas, deletion of the expression of NeuGc and expression of human complement-regulatory proteins in the pig cornea will be important if prolonged clinical corneal xenograft survival is to be achieved.

Influence of different keratoplasty techniques on the biomechanical properties of the cornea

PURPOSE

To evaluate and compare corneal biomechanical changes after deep anterior lamellar keratoplasty (DALK) versus penetrating keratoplasty (PK) using the ocular response analyzer (ORA).

METHODS

This prospective comparative study included 65 eyes (65 patients). Patients were divided into three groups: DALK (20 eyes), PK (25 eyes) and control group of normal subjects (20 eyes). Ocular response analyzer was used to measure corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure and cornea-compensated intraocular pressure at 6 and 12 months postoperatively. Central corneal thickness (CCT) was measured using ultrasonic pachymetry.

RESULTS

Both mean CH and mean CRF were significantly lower in PK group (sutures on; 10.1 ± 1.11 and 9.6 ± 1.08 mmHg) than in DALK (sutures out; 12.25± 1.13 and 12.09 ± 1.05 mmHg) and control groups (12.98 ± 1.19 and 12.59 ± 0.94 mmHg) at 6 months, respectively (p <0.0001). After 1 year, there was no statistically significant difference in mean CH and CRF between DALK (12.68 ± 1.11 and 12.18 ± 1.11 mmHg) and PK groups (still sutures on; 12.36 ± 1.32 mmHg, p = 0.39 and 11.83 ± 1.26 mmHg, p = 0.33, respectively); however, the mean CRF was significantly lower in the PK than the control group (p = 0.03). No statistically significant difference in mean CH or mean CRF was found between DALK and control groups at any time-point.

CONCLUSIONS

Compared with PK, DALK provides rapid return of normal corneal biomechanics, perhaps because of the combined healing at both the deep interface and graft margin, shorter period of steroid treatment and the intactness of Descemet membrane in these eyes.

Comparison of clinical outcomes of same-size grafting between deep anterior lamellar keratoplasty and penetrating keratoplasty for keratoconus

Purpose

To compare the clinical outcomes between deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PKP) with same-size grafts in patients with keratoconus.

Methods

Medical records of 16 eyes from 15 patients treated from June 2005 through April 2011 were retrospectively reviewed. Patients with contact lens intolerance or who were poor candidates for contact lens fitting due to advanced cone underwent keratoplasty. The transplantations consisted of 11 DALK and 5 PKP with same-size grafting for keratoconus. Best-corrected visual acuity (BCVA), refractive error, corneal topographic profiling, and clinical course were compared between DALK and PKP groups.

Results

The follow-up period was 30 ± 17 months in the DALK group and 45 ± 20 months in the PKP group (p = 0.145). At final follow-up, the DALK and PKP groups achieved a BCVA (logarithm of the minimum angle of resolution) of 0.34 and 0.52, respectively (p = 0.980). Postoperative refractive error and mean simulated keratometric index showed myopic astigmatism in both groups without any statistical difference. Corneal irregularity index measured at 5 mm in the DALK group was less than that of the PKP group at 1-year follow-up (p = 0.021); however, at final follow-up, there was no longer a statistically significant difference. Endothelial cell counts were lower in the PKP group than in the DALK group at final follow-up (p = 0.021).

Conclusions

The optical outcomes of DALK with same-size grafts for keratoconus are comparable to those of PKP. Endothelial cell counts are more stable in DALK compared to PKP.

A retrospective contralateral study comparing deep anterior lamellar keratoplasty with penetrating keratoplasty

PURPOSE

This study was conducted to compare endothelial cell (EC) loss, visual outcomes, and complications after deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) in the contralateral eyes of the same patients.

METHODS

A retrospective cohort study was undertaken at the Samsung Medical Center, Seoul Korea. We reviewed the records of 8 patients (16 eyes) who underwent PK in one eye and DALK in the contralateral eye. The DALK procedures were performed according to the Anwar and Teichmann big-bubble technique. EC loss, visual acuity, refractive status, and complications were evaluated to compare these techniques.

RESULTS

EC density was significantly higher after DALK compared with PK (at 12 months: 2045.8 ± 664.8 vs. 1732.6 ± 793.2, P = 0.044; at 24 months: 1900.3 ± 352.2 vs. 1416.2 ± 456.1, P = 0.013). The mean postoperative refractive astigmatism was -3.46 ± 2.57 diopters in the DALK-operated eyes versus -3.38 ± 2.48 diopters in the PK-operated eyes (P = 0.780), and the mean postoperative best-corrected visual acuity was 0.14 and 0.13 logarithm of the minimum angle of resolution, respectively (P = 0.870). There were no significant differences in the uncorrected visual acuity, best-corrected visual acuity, and refractive error between the DALK-operated and PK-operated eyes throughout the follow-up period. Rejection episodes were reported in 2 PK-operated eyes. No graft failures occurred.

CONCLUSIONS

Over the 2-year follow-up after DALK, EC loss was significantly lower, whereas the visual outcomes were comparable with those of the PK-operated eyes. No endothelial rejection occurred in the DALK-operated eyes. DALK is an effective alternative surgical procedure for corneal stromal pathologies.

Characterization of porcine corneal endothelium for xenotransplantation

PURPOSE

Endothelial keratoplasty (EKP) has become increasingly popular in the treatment of corneal disease. However, the global shortage of human donor corneas limits clinical corneal transplantation. Genetically engineered (GE) pigs may provide an alternative source of corneas for EKP. The aim of this study was to evaluate corneal endothelial cells (CECs) from wild-type (WT) and GE pigs.

METHODS

Density, size of CECs, and the percentage of hexagonal cells (as a measure of heterogeneity) were measured by ex vivo confocal microscopy in corneas from WT and GE pigs of different ages - neonatal (4-5 days), young (5-15 weeks), adult (5-15 months), and old (20-42 months). α1,3-galactosyltransferase gene-knockout (GTKO) pigs transgenic for the human complement-regulatory protein(s), CD46 (GTKO/CD46) +/- CD55 (GTKO/CD46/CD55) were used as sources of GE corneas.

RESULTS

Mean CEC densities (cells/mm²) were neonatal (5968), young (3789), adult (2589), and old (2070). As with human corneas, there was an age-dependent decrease in pig CEC density and increase in pig CEC size. However, unlike human corneas, there was no correlation between the percentage of hexagonal cells (approximately 50% in all pig corneas) and age, suggesting that heterogeneity is intrinsic for pig corneas. Genetic modification did not affect CEC density, size, or morphology compared to WT pigs.

CONCLUSION

Because of the availability of young pigs and their greater CEC density (and the protection afforded against the human immune response), GE pigs could provide an unlimited source of corneas for clinical EKP.

Enzyme-assisted deep anterior lamellar keratoplasty-a new method of lamellar dissection-a wetlab-based pilot study

PURPOSE

To explore the safety of a new technique of lamellar dissection, using enzymatic digestion of the corneal stroma and extracellular matrix.

METHODS

This was a wetlab-based pilot study of hyaluronidase and trypsin-assisted deep anterior lamellar keratoplasty (DALK) in cadaveric human corneal tissue. Enzyme-assisted DALK was performed on 17 tissues. These underwent histologic analysis using a pneumatic dissection specimen as control. Rates of perforation and Descemet membrane (DM) exposure were recorded by clinical observation and by optical coherence tomography in selected cases. Where possible, pre- and postsurgical endothelial cell counts were obtained via specular microscopy. Two tissues from the same donor were halved, with each half soaked in a different solution (Optisol, balanced salt solution, hyaluronidase, and trypsin) for 13.5 hours to observe maximal effect.

RESULTS

Successful exposure of DM was achieved in 8 specimens. In the remaining 9, manual dissection was possible to a residual depth of 25 to 90 μm where measured with optical coherence tomography. Three tissues had perforation of DM, all via manual maneuvers. No deleterious effects on residual host tissue were observed by light microscopy with no significant rates of endothelial cell loss in 8 tissues in which a predissection cell count was obtainable. The 2 enzymes had differing effects on soaked specimens that were reflected intraoperatively.

CONCLUSION

Preliminary results of this ex vivo study are encouraging that enzymolysis may represent an effective innovation in DALK surgery with an acceptable safety profile. Further studies are required to refine the technique and application of the enzymes in vivo.

Deep anterior lamellar keratoplasty for the management of iatrogenic keratectasia occurring after hexagonal keratotomy

Iatrogenic keratectasia has been reported subsequent to refractive surgery or trauma. Hexagonal keratotomy (HK) is a surgical incisional technique to correct hyperopia. A number of complications have been reported following this procedure, including irregular astigmatism, wound healing abnormalities and corneal ectasia. When visual acuity is poor because of ectasia or irregular astigmatism and contact lens fitting is not possible, penetrating or lamellar keratoplasty can be performed. Since incisions in refractive keratotomy are set at 90–95% depth of cornea, intraoperative microperforations are known to occur and lamellar keratoplasty may become difficult. We describe deep anterior lamellar keratoplasty (DALK) used to successfully manage keratectasia after HK. Pre DALK vision was 20/400 and post DALK vision was 20/30 two months after surgery. This report aims to show improved visual outcome in corneal ectasia secondary to HK. DALK can be a procedure of choice with proper case selection.

Descemetic versus pre-descemetic lamellar keratoplasty: clinical and confocal study

PURPOSE

To compare the clinical findings and confocal microscopic features of the lamellar interface after 2 types of deep anterior lamellar keratoplasty (DALK): Descemetic with total stromal resection versus pre-Descemetic with deep stromal dissection.

METHODS

Twenty eyes of 20 patients who had corneal disease with healthy endothelium were treated by DALK using the air technique. Baring of Descemet membrane (DM) was achieved for 12 eyes (Descemetic group). A fine stromal layer was left in 8 eyes (pre-Descemetic group). Visual acuity, interface clarity, corneal topography, confocal microscopy, and endothelial cell count were analyzed.

RESULTS

DM microperforation occurred in 2 eyes (10%). No patient required conversion to penetrating keratoplasty (PKP) intraoperatively. Presumed stromal rejection occurred in 1 eye that was excluded from the study. In the Descemetic group, 90.9% achieved final best-corrected visual acuity (BCVA) of 20/30 or better; in the pre-Descemetic group, 75% achieved final BCVA of 20/30 or better. No statistically significant difference in mean visual outcomes was found between groups. The reflectivity of activated keratocytes at the interface was less in the Descemetic than that in the pre-Descemetic group. Ten to 12 weeks after pre-Descemetic DALK and 4 to 6 weeks after Descemetic DALK, keratocyte morphology and reflectivity had returned to normal. Mean combined topographic astigmatism was 2.17 ± 0.75 diopters (D) at 6 months (sutures out).

CONCLUSIONS

The depth of the lamellar bed, smoothness, and healing process at the interface are the keys to optimal visual acuity. Although dissection to bare DM is more difficult, keratocyte activation and interface haze were less, but differences in final visual acuity were not significant.

Deep anterior lamellar keratoplasty: indications, surgical techniques and complications

The concept of lamellar keratoplasty (LK) is not new. However, it had been abandoned and largely replaced by the time-honored technique of penetrating keratoplasty (PK) because LK is technically demanding, time consuming and gives suboptimal visual outcomes due to interface irregularity arising from manual lamellar dissection. Recent improvements in surgical instruments and introduction of new techniques of maximum depth of corneal dissection as well as inherent advantages such as preservation of globe integrity and elimination of endothelial graft rejection have resulted in a re-introduction of LK as an acceptable alternative to conventional PK. This review article describes the indications, different techniques, clinical outcomes and complications of deep anterior LK.

Dissection plane in deep anterior lamellar keratoplasty using the big-bubble technique

PURPOSE

To find the level of dissection in keratoconic corneas undergoing deep anterior lamellar keratoplasty (DALK) using the big-bubble technique.

METHODS

In 3 keratoconic eyes that underwent DALK, the operation was converted into penetrating keratoplasty after complete big-bubble formation because of extensive tear in Descemet's membrane (DM) during stromal excision. The corneal stroma and DM taken from these eyes were submitted for light and transmission electron microscopy.

RESULTS

Both light and transmission electron microscope revealed a thin layer of corneal stroma adhered to DM in all cases. In 2 eyes, the residual stromal thickness was almost constant (6.4 μm and 12.3 μm), whereas it varied from 9.5 μm to 25.8 μm in the other one.

CONCLUSION

Dissection plane in DALK using the big-bubble technique can be within corneal stroma rather than exactly between stroma and DM. Various corneal pathologies as well as different techniques of dissection may have influence on this level.

Deep anterior lamellar keratoplasty versus penetrating keratoplasty for keratoconus: a clinical trial

PURPOSE

To compare deep anterior lamellar keratoplasty (DALK) using the big-bubble technique to penetrating keratoplasty (PK) in patients with keratoconus.

MATERIALS AND METHODS

In this clinical trial, patients with moderate to advanced keratoconus with poor spectacle-corrected visual acuity and intolerant to contact lens wear were enrolled. DALK was performed using the big-bubble technique, and a full-thickness donor cornea without Descemet membrane was sutured to the recipient bed. PK was performed conventionally with a Hessburg-Barron suction trephine. Three types of suturing were used for both groups. Postoperative refractive errors, best-corrected visual acuity (BCVA), contrast sensitivity function (CSF), and higher order aberrations (HOAs) were compared between the study groups.

RESULTS

The study included 81 eyes of 81 patients. Forty-six eyes underwent DALK from which 4 were excluded because of failure to achieve bared Descemet membrane. Thirty-five eyes received PK. Mean patient age was 26.91 ± 7.9 versus 30.89 ± 10.3 years in the DALK and PK groups, respectively (P = 0.06). Mean follow-up period was 22.0 ± 7.9 months in the DALK group and 24.6 ± 3.5 months in the PK group (P = 0.32). Mean postoperative spherical equivalent refractive error was -3.23 ± 3.4 diopters in the DALK group versus -2.22 ± 4.6 diopters in the PK group (P = 0.28), and mean postoperative BCVA was 0.18 ± 0.08 and 0.15 ± 0.10 logarithm of the minimum angle of resolution, respectively (P = 0.12). CSF and total aberrations and HOAs were comparable in the study groups.

CONCLUSIONS

DALK is an effective alternative surgical procedure for patients with keratoconus; the outcomes are comparable to PK in terms of refractive errors, BCVA, CSF, and HOAs.

Deep anterior lamellar keratoplasty in patients with keratoconus: big-bubble technique

PURPOSE

To evaluate the visual and refractive outcomes after deep anterior lamellar keratoplasty (DALK) using the big-bubble technique in eyes with keratoconus.

METHODS

In this case series, eyes with moderate to advanced keratoconus underwent DALK. All of them had unacceptable spectacle-corrected visual acuity or were contact lens intolerant. DALK was performed using the big-bubble technique. Full thickness donor cornea without Descemet's membrane (DM) was sutured to the recipient bed with three different suturing techniques. The visual acuity (presented in logMAR), refractive status, intraoperative and postoperative complications were evaluated.

RESULTS

A total of 129 consecutive eyes of 121 patients were included. In 3 eyes, the operation was converted to penetrating keratoplasty. Therefore, 126 eyes (79 male) were enrolled in the study. Mean patient age at the time of surgery was 26.08 +/- 7.6 years. Mean follow-up period was 21.62 +/- 9.0 months. Mean preoperative corrected visual acuity was 1.27 +/- 0.4 logMAR, increasing to 0.25 +/- 0.2 logMAR at final follow-up examination (P < 0.001). Postoperative mean spherical equivalent refractive error, refractive and keratometric astigmatism were -3.41 +/- 3.1 D, 3.04 +/- 2.3 D, and 3.67 +/- 2.1 D, respectively. Bared DM was achieved in 103 eyes, whereas in 23 eyes pre-Descemet dissection was performed. DM perforation occurred in 5 eyes. The main complications encountered were filamentary keratitis, subepithelial graft rejection, and astigmatism.

CONCLUSIONS

: DALK using the big-bubble technique appears to be a safe and effective procedure for eyes with moderate to advanced keratoconus. In case of extensive intraoperative DM perforation, it does not pose any limitation to ongoing penetrating keratoplasty.

[Surgical treatment of ocular surface diseases]

Pathomechanisms leading to ocular surface diseases are difficult to influence, and conservative treatment efforts are inefficient in most cases. However, the development of microsurgical techniques, the clinical application of molecular biologic methods and the localisation and identification of the function of limbal stem cells made it possible to achieve visual improvement and quality of life in these cases. The authors review the methods of tissue harvesting, cell culturing, transplantation techniques and indications. They provide a detailed survey on the most recommended modern surgical procedures, especially focusing on amniotic membrane and limbal stem cell transplantation.

Impact of the descemet membrane perforation on surgical outcomes after deep lamellar keratoplasty

PURPOSE

To study the influence of the Descemet membrane (DM) perforations after deep lamellar keratoplasty (DLKP) on endothelial decompensation, endothelial density, visual acuity, and postoperative complications. The relationship between DM perforations and pseudoanterior chamber formation also was studied.

DESIGN

Retrospective study.

METHODS

Ninety-six consecutive eyes of 89 patients who underwent DLKP with and without DM perforation were studied. The eyes with DM perforation were divided further into two groups: macroperforation and microperforation. Main outcome measures included graft survival, postoperative pseudochamber formation, endothelial density, and best spectacle-corrected visual acuity (BSCVA).

RESULTS

Overall, 88 of 96 eyes (91.7%) had clear grafts. Endothelial decompensation developed in three eyes (13.0%) in the eyes with perforation, which was significantly higher than in the eyes without perforation (1.4%; P = .047). Postoperative pseudochamber formation was observed in 60.0% in the perforated eyes, which was significantly higher than that observed in the imperforated eyes (19.7%; P = .0003). In the eyes with perforation, mean endothelial cell density was significantly decreased compared with that of the imperforated eyes at three and six months after surgery (P = .0497 and P = .0002, respectively). Three months after surgery, BSCVA in the imperforated eyes was significantly better than that in the perforated eyes (P = .016). Eyes with macroperforation were more likely to develop both pseudochamber and endothelial decompensation than eyes with microperforation.

CONCLUSIONS

Perforation of DM adversely affected endothelial decompensation and endothelial density after DLKP, especially in cases where perforations were large.

Deep lamellar keratoplasty by intracorneal dissection: a prospective clinical and confocal microscopic study

OBJECTIVE

To evaluate the clinical findings, visual outcomes, and confocal microscopic corneal features of a surgical technique for manual deep lamellar keratoplasty (DLKP) with intentional sparing of the most posterior stroma.

DESIGN

Noncomparative, prospective, 12-month interventional study.

PARTICIPANTS

Forty-six eyes of 45 patients who had corneal pathologic features without endothelial abnormalities and requiring corneal graft were treated by DLKP by manual stromal delamination. They were examined clinically after surgery and using in vivo confocal microscopy at 2 weeks and 1, 3, 6, and 12 months.

INTERVENTION

The surgical technique consisted of an intracorneal deep manual stromal dissection through a 4-mm limbal incision at 50 mum from Descemet's membrane (DM). After trephination, an endothelial free graft was sutured.

MAIN OUTCOME MEASURES

Topographic parameters, interface depth and reflectivity, and anterior and postinterface keratocyte density; visual acuity was correlated with these parameters.

RESULTS

Two eyes had rupture of the DM. Two eyes that had delayed epithelial healing because of graft override with stromal inflammation underwent a second surgery (penetrating keratoplasty). Mean uncorrected logarithm of the minimum angle of resolution (logMAR) uncorrected visual acuity and logMAR best-corrected visual acuity (BCVA) improved from preoperative values (1.342+/-0.239 and 0.923+/-0.226, respectively) to 0.421+/-0.122 and 0.104+/-0.068, respectively, at 12 months. Mean topographic astigmatism was 3.09+/-1.30 diopters (D) at 3 months after suture adjustment, and 2.87+/-0.92 D at 12 months after suture removal. Average interface depth was 64.2+/-6.7 microm at 15 days and showed no significant changes up to 12 months. Mean interface reflectivity was highest at 15 days (95.5+/-15.7 light reflectance units [LRU]) and showed a progressive decrease over time of 55.3+/-8.7 LRU at 12 months. A significant negative correlation was observed between BCVA and topographic astigmatism up to 1 month and between BCVA and interface reflectivity starting from 6 months after surgery.

CONCLUSIONS

Deep lamellar keratoplasty by intracorneal dissection provides visual and clinical results comparable with that of other DLKP techniques. Visual recovery is slow and progressive, taking up to 1 year. Confocal microscopy enables precise evaluation of corneal features, interface morphologic features, and reflectivity, demonstrating a negative correlation between interface reflectivity and BCVA showing that the progressive recovery over months of the interface transparency is correlated with the increase in visual acuity after 6 months.

Deep Lamellar Keratoplasty in the Treatment of Keratoconus

PURPOSE

To present our experience with a series of patients treated with deep lamellar keratoplasty (DLK) for keratoconus (KC).

DESIGN

A single surgeon, prospective, consecutive series.

METHOD

The study included all patients with KC who underwent DLK between March 1999 and November 2003 at the Royal Adelaide Hospital. The parameters evaluated included patients' demographics, pre- and post-operative best corrected visual acuities, post-operative keratometry, and intra- and post-operative complications.

RESULTS

There were 22 patients (23 eyes); 10 females and 12 males, with a mean age of 35 +/- 13 years (median, 33.5; range, 17-73). The median follow-up period was 13 months (range 7-38). In 89% (16/18) of eyes which underwent DLK, and in which a visual acuity could be obtained, a best corrected visual acuity of at least 6/12 was recorded. There were two episodes of Descemet's membrane perforation (8.7%), in which the procedure was converted to penetrating keratoplasty without complications. One patient developed a double anterior chamber, which resolved spontaneously without consequences.

CONCLUSION

The visual outcomes and complication rates seen in our series are comparable to the recent published literature. Hence DLK can be considered as a suitable alternative to penetrating keratoplasty for the surgical treatment of KC.

Compressive C-shaped lamellar keratoplasty

OBJECTIVE

To describe a compressive lamellar surgical technique for treating severe astigmatism in peripheral corneal ectasia.

DESIGN

Retrospective, noncomparative, interventional case series.

PARTICIPANTS

Four eyes of 3 patients with either pellucid or Terrien's marginal corneal degeneration were included in this series.

METHODS

C-shaped lamellar keratoplasty using multiple trephines of different sizes, with deliberate undersizing of the donor graft for a controlled compressive effect, was performed on these patients.

MAIN OUTCOME MEASURES

Visual acuity outcome and refraction were measured at different intervals at up to 40 months of follow-up.

RESULTS

All eyes achieved Snellen visual acuity of 20/40 or better and stable astigmatism ranging from 0 to -2.75 diopter cylinder within 6 months, with no recurrence of corneal thinning or peripheral corneal vascularization.

CONCLUSIONS

Compressive C-shaped lamellar keratoplasty is able to reduce severe corneal astigmatism in peripheral corneal ectasia and can result in good visual and refractive outcomes with early visual rehabilitation.

Automated superficial lamellar keratectomy augmented by excimer laser masked PTK in the management of severe superficial corneal opacities

AIM

To assess superficial lamellar keratectomy augmented by excimer laser smoothening with sodium hyaluronate 0.25%, for the management of superficial corneal opacities.

METHODS

Consecutive procedure performed in 14 eyes (13 patients) with an automated microkeratome and excimer laser phototherapeutic keratectomy (PTK) smoothening using sodium hyaluronate 0.25%.

MAIN OUTCOME MEASURES

UCVA, BCVA, pachymetry, degree of haze, ray tracing analysis, and complications. Mean follow up was 12 (SD 1.6) months.

RESULTS

Mean preoperative haze from previous corneal refractive surgeries was 3.5 (SD 0.5) (11/14 cases). In one case, opacity was caused by ocular trauma and in two by infectious keratitis. The mean preoperative UCVA was 0.7 logMAR (0.2 (SD 0.13) decimal value). BCVA was 0.4 logMAR (0.4 (SD 0.17) decimal value). Mean preoperative corneal pachymetry was 508 (SD 62.5) micro m and mean opacity depth measured by corneal confocal microscopy was 115.2 (SD 49.4) micro m. At 6 months, 71.4% of the eyes with previous corneal refractive surgery showed grade I haze or less. Mean postoperative corneal pachymetry at 6 months was 352.36 (SD 49.05) micro m.

CONCLUSIONS

Automated superficial lamellar keratectomy combined with excimer laser PTK smoothening assisted by sodium hyaluronate 0.25% induces a significant improvement of corneal transparency and visual acuity in cases of corneal opacity caused by previous refractive surgery, ocular trauma, and keratitis.

Anterior Lamellar Keratoplasty With a Microkeratome: A Method for Managing Complications After Refractive Surgery

PURPOSE

To demonstrate a technique of anterior lamellar keratoplasty with standardized and automated preparation of surface-parallel cuts in both donor and recipient appropriate for addressing several problems after laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK).

METHODS

We report a noncomparative series of ten eyes with complications after LASIK and PRK. Lamellar cuts were performed in donor and recipient eyes by means of an automated microkeratome. Lamellar grafts were fixed by only four single sutures. In two eyes, a re-lift LASIK was performed after 6 months.

RESULTS

Surgery was uneventful and visual acuity was improved in all eyes. Residual irregular astigmatism and refractive error were corrected in two eyes by means of excimer laser computer-assisted ablation and resulted in a further improvement of uncorrected and best spectacle-corrected visual acuity.

CONCLUSIONS

Anterior lamellar keratoplasty with a microkeratome can be used for the management of certain complications of PRK and LASIK.

Evaluation of a microkeratome-based limbal harvester device for limbal stem cell transplantation

PURPOSE

To assess the cut quality and reproducibility using a novel microkeratome-based limbal harvester.

METHODS

An enlarged microkeratome head and stainless steel blades were coupled with a nitrogen gas-driven turbine (15,000 blade oscillations/min) of a microkeratome. A large, 16-mm-diameter suction ring was attached to the globe. A lamellar sclerokeratectomy using head depths of 170 and 200 microm was performed in human donor research eyes. Obtained lenticule thickness was measured by ultrasound pachymetry and the bed size by planimetry. Histologic and scanning electron microscopy (SEM) analyses of the samples were performed.

RESULTS

Central lenticule thickness was 294 microm (standard deviation [SD] 37) for the 170 head and 277 microm (SD 91) for the 200 head (p = 0.720). Lenticule diameter was larger in the horizontal meridian using the 170 head (12.8 mm [SD 0.8] vs. 11.9 mm [SD 0.7], p = 0.028), but similar in vertical meridian (12.0 [SD 0.6] versus 11.4 mm [SD 0.6], p = 0.093). Histology showed a multilayer epithelial cell pattern at the lenticule periphery. The SEM showed a smooth cut surface in both the stromal bed and the lenticule.

CONCLUSION

Cut reproducibility and quality are similar to those found using standard microkeratomes for corneal lamellar cuts. This system ensures, in a straightforward way, the presence of epithelial cells in the edges of a mechanical sclerokeratectomy for limbal stem cell transplantation.

Growth factor changes in ex vivo expansion of human limbal epithelial cells on human amniotic membrane

PURPOSE

Human limbal epithelial cells cultured on human amniotic membrane have been used for transplantation to treat corneal surface injuries. We determined whether the amniotic basement membrane affects the growth of human limbal epithelial cells through the production of growth factors.

METHODS

The epithelial cells grown out from limbal basal epithelium were placed on conventional culture plastic or on the epithelial side of denuded amniotic membrane under serum-free conditions. Culture supernatant was assayed for growth factor release at 24, 48, and 96 hours.

RESULTS

The cells grown on both substrata produced similar levels of epidermal growth factor (EGF). Cells grown on amniotic membrane showed enhanced secretion of tissue inhibitor of metalloproteinase type 1 (TIMP1) and reduced production of transforming growth factor beta1 and beta2. Depletion of EGF and TIMPI in cell culture slowed down cell growth and reduced EGF receptor expression, respectively.

CONCLUSION

Increased TIMPI influences the proteolytic system in the cell and extracellular matrix interaction, and decreased transforming growth factor beta1 and beta2 may stimulate corneal cell proliferation. We show that the amniotic membrane leads to differential expression of cytokines of limbal epithelial cells cultured on its surface. Such effects may be favorable to the growth and differentiation of the cells when used for ocular surface reconstruction.