Impact of new lamellar techniques of keratoplasty on eye bank activity

Review for special issue: Corneal lamellar surgery: Present outcomes and future perspectives

Since the establishment of the first eye bank in the 1940s, their role has evolved to face new challenges. With the recent development of lamellar keratoplasties, eye banks play an even bigger role in the selection and preparation of donor tissues. The increasing number of keratoplasty techniques and the high demand for "ready-to-use" tissues are challenging eye banks to improve and develop new preparation techniques. Besides necessary examinations, new approaches of tissue analysis in eye banks allow a better/optimized selection of corneal tissues. These new challenges in tissue preservation, preparation, and selection are propelling eye banks into a new era of modern eye banking.

Repeat deep anterior lamellar keratoplasty (DALK) for failed primary DALK

Purpose

To evaluate the effectiveness of repeat deep anterior lamellar keratoplasty (DALK) in patients of previous failed DALK.

Methods

: A retrospective analysis of records of seven patients who had undergone repeat DALK following the failure of the primary DALK was done. The indications for repeat surgery, time elapsed since the first surgery, and pre- & postoperative best-corrected visual acuity (BCVA) were noted for all the patients.

Results

The follow-up period ranged between one- to four-year post repeat DALK. The indication of primary DALK was keratoconus with vernal keratoconjunctivitis (VKC) (n = 3), corneal amyloidosis (n = 2), Salzman nodular keratopathy (n = 1), and healed keratitis (n = 1). The need for repeat surgery arose when the BSCVA dropped to less than 20/200. The time interval elapsed since the first surgery ranged from two months to four years. Postoperatively, the BSCVA improved from 20/120 to 20/30 at the end of one-year post repeat DALK in all except one patient. All regrafts were clear at the most recent examination, performed after a mean period of 18 months after the secondary graft. No complication was encountered during the resurgery. The dissection of the host bed was easier in the second surgery owing to weaker adhesions.

Conclusion

The prognosis for repeat DALK for failed DALK is excellent, and the outcomes of secondary grafts were comparable to those of primary DALK grafts. Re DALK offers the advantage of an easier dissection and lower chances of graft rejection compared to penetrating keratoplasty.

Surgical management of glaucoma following different keratoplasty techniques

PURPOSE

To investigate the results of surgical management of glaucoma following different keratoplasty techniques.

METHODS

Medical records of 628 cases who underwent keratoplasty were reviewed. One hundred and eighty-eight patients (29.9%) who developed post-keratoplasty glaucoma were evaluated. Patients who could not be controlled with maximal medical treatment and underwent glaucoma surgery were included in this study. Trabeculectomy, Ahmed glaucoma valve (AGV) implantation or diode laser cyclophotocoagulation (DLC) were applied.

RESULTS

Glaucoma surgery was performed in 55 (29.3%) patients who had uncontrolled post-keratoplasty glaucoma. In penetrating keratoplasty group (n = 42), DLC was applied to 30 (71.4%) eyes, AGV to 11 (26.2%) eyes, and trabeculectomy in 1 (2.4%) eye. In Descemet's membrane endothelial keratoplasty group (n = 8), DLC was applied to 4 (50%) eyes, trabeculectomy for 3 (37.5%) eyes and AGV for 1 (12.5%) eye. In deep anterior lamellar keratoplasty group (n = 5), DLC was applied to 2 (40%) eyes, trabeculectomy to 2 (40%) eyes and AGV to 1 (20%) eye. While a statistically significant decrease was found in intraocular pressure (IOP) and anti-glaucomatous medication after surgery (p < 0.05 for each), no significant difference was found in best corrected visual acuity (BCVA). During follow-up, DLC was applied as re-glaucoma surgery in 19 (34.5%) cases. A significant reduction in IOP together with number of anti-glaucomatous medications was found with re-operation; however, a significant decrease in BCVA was noted (p < 0.05 for each).

CONCLUSION

Glaucoma surgeries after keratoplasty are effective in decreasing IOP and the number of anti-glaucomatous medication. While BCVA doesn't change after the first glaucoma surgery, after re-operation significant decrease may occur.

Femtosecond laser-assisted implantation of corneal stroma lenticule for keratoconus

Purpose

To review recent progress, challenges, and future perspectives of stromal keratophakia for the treatment of advanced keratoconus.

Methods

We systematically reviewed the literature in the PubMed database, last update June 30, 2020. No language restriction was applied. The authors checked the reference lists of the retrieved articles to identify any additional study of interest.

Results

Several techniques have been proposed for the treatment of keratoconus in order to avoid or delay keratoplasty. This was primarily due to the lack of accessibility to donor corneas in many countries. The ease and predictability of the more advanced femtosecond lasers used to correct ametropias by stromal lenticule extraction lead to hypothesize that generated refractive lenticules could be implanted into corneal stromal layers to restore volume and alter the refractive properties of the cornea in patients with corneal ectasias. At the same time, new techniques for preservation, customization, and cellular therapy of the corneal stromal have been developed, directing to the valorization of otherwise discarded byproducts such as donor corneas unsuitable for either lamellar of penetrating keratoplasty.

Conclusions

Femtosecond laser-assisted stromal keratophakia could be a suitable therapeutic option for the treatment of corneal ectasias, especially in patients with advanced keratoconus, providing biomechanical support recovering the pachimetry to nearly normal value at the same time. The accuracy and predictability of the refractive outcome are yet a critical issue and the patient eligible for the procedure still has to be characterized.

Corneal transplantation trends in France from 2004 to 2015: A 12-year review

Purpose:

The aim of this study was to report the 12-year longitudinal trends in indication and corneal transplantation techniques in France from 2004 to 2015.

Results:

The records of all corneal transplantations performed from 2004 to 2015 in France were retrospectively reviewed. The patient indications and types of transplant performed were analyzed. A total of 46,658 corneal transplantations were performed between 2004 and 2015, with 34,187 (73.3%) penetrating keratoplasty and 10,452 (22.4%) lamellar keratoplasty. The leading surgical indications were secondary endothelial failure (24.3%), keratoconus (18.8%), regraft (13.5%), and Fuchs endothelial corneal dystrophy (15.1%). Endothelial keratoplasty became the preferred technique for endothelial diseases and deep anterior lamellar keratoplasty the preferred technique for keratoconus, surpassing penetrating keratoplasty in 2013.

Conclusion:

Secondary endothelial failure is the top indication for performing a keratoplasty over the 12-year period. There was a shift from penetrating keratoplasty to endothelial keratoplasty performed for Fuchs endothelial corneal dystrophy and secondary endothelial failure, and to deep anterior lamellar keratoplasty, performed for keratoconus. This highlights an important shift in managing corneal diseases toward the application of selective and more conservative surgeries and changes in indications in corneal transplantation.

Changing trends in corneal graft surgery: a ten-year review

AIM

To review indications and corneal tissue use for penetrating and lamellar surgery between 2002 and 2011.

METHODS

The surgical reports of corneal grafts performed during 2002-2011, using tissues supplied by the Eye Bank of Piedmont (Italy), were reviewed retrospectively. Patient demographic data, date of intervention, indication for surgery, and surgical technique used were recorded. Surgical techniques included penetrating keratoplasty (PK), deep anterior lamellar keratoplasty (DALK) and endothelial keratoplasty (EK). The χ (2) test was used to compare the distribution of indications and types of surgical technique used, for corneal grafts done during 2002-2006 versus those done during 2007-2011.

RESULTS

The number of corneal grafts increased by 30.7% from 2002-2006 to 2007-2011 (from 1567 to 2048). Comparing the two periods, both main indications and surgical techniques changed significantly. In 2007-2011, the proportion of interventions for aphakic/pseudophakic bullous keratopathy (from 16.8% to 21.3%), graft failure (from 16.4% to 19.1%) and Fuchs endothelial dystrophy (from 12.8% to 16.7%) all increased significantly (P<0.05), while those for keratoconus decreased significantly (from 35.6% to 27.3%; P<0.001). In 2007-2011, the proportion of PK decreased significantly (from 92.4% to 57.2%; P<0.001) while that of EK and DALK went from 0.4% to 30.2% (P<0.001) and from 7.2% to 12.6% (P<0.001) respectively.

CONCLUSION

During 2002-2011 the number of interventions increased significantly for corneal endothelial diseases and graft failure. The growing demand for interventions for these diseases corresponded to the widespread adoption of EK techniques. The use of DALK also increased, but more moderately than EK procedures.

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.

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.

Application of the femtosecond laser LASIK microkeratome in eye banking

PURPOSE OF REVIEW

To review the literature for recent advancements in the femtosecond laser technology with regard to its applications in corneal transplantation and eye banking.

RECENT FINDINGS

Advancements in corneal surgery have encouraged the use of disease-specific corneal subcomponents, utilized in procedures such as anterior-lamellar keratoplasty and endothelial keratoplasty, instead of traditional transplant procedures to minimize adverse effects of penetrating keratoplasty. Femtosecond laser microkeratomes can precisely create flaps for such transplant procedures, achieve better wound stability, and promote healing by shaped wound configurations. Laser microkeratomes have been compared to traditional mechanical microkeratomes for keratoplasty procedures from various aspects and are superior in some aspects and offer unique capabilities.

SUMMARY

Femtosecond laser applications in eye banking include preparation of donor and recipient corneas for use in penetrating keratoplasty, anterior-lamellar keratoplasty, and endothelial keratoplasty. Advantages of femtosecond laser microkeratomes include higher precision of the cut, ability to achieve thinner flaps, and wound configurations that allow greater wound stability, shorter recovery time, and less postoperative pain. However, cost and availability at the eye-bank level may hinder widespread and immediate application.