Effect of donor graft quality on clinical outcomes after deep anterior lamellar keratoplasty. Cornea. 2014;33:795-800. [PMID: 24977989 DOI: 10.1097/ico.0000000000000177]

Suture-related complications after deep anterior lamellar keratoplasty for keratoconus

PURPOSE

The purpose of this study is to determine the incidence of suture-related complications, their risk factors, and effects on the clinical outcomes after deep anterior lamellar keratoplasty (DALK) for keratoconus.

METHODS

In this retrospective, comparative, interventional study, the records of consecutive patients with keratoconus who underwent DALK were reviewed for suture-related complications. Univariate analyses were used to identify risk factors for suture complications. We compared groups with and without suture-related complications to evaluate the effects of these complications on clinical outcomes after DALK.

RESULTS

Of the 633 DALKs, 438 eyes (69.2%) developed suture complications including loose sutures (32.7%), spontaneous suture rupture (30%), sterile suture abscesses (22.8%), suture tract vascularization (16.4%), suture erosion (10.3%), and suture cheese wiring (6.8%). Vernal keratoconjunctivitis increased the incidence of sterile suture infiltration, premature suture loosening, and suture tract vascularization. Loose suture was observed more commonly in larger graft size, while spontaneous suture rupture was associated with late suture removal. There was no statistically significant difference in postoperative outcomes including visual acuity, refraction, graft rejection, and failure in eyes with and without suture complications. However, suture-related complications were directly associated with sight-threatening ocular morbidities, including graft rejection (39 eyes), ulcer (1 eye), and failure (2 eyes).

CONCLUSION

Suture-related complications frequently occurred after DALK for keratoconus. Ocular surface inflammation, large grafts, and late suture removal increased the risk of suture-related complications. While these complications had no negative impact on clinical outcomes in the majority of cases, some of them led to sight-threatening morbidity, underlining the importance of early diagnosis and treatment.

Descemetic Deep Anterior Lamellar Keratoplasty versus Penetrating Keratoplasty in Advanced Keratoconus: Comparison of Visual and Refractive Outcomes

Purpose

To assess and contrast the visual and refractive results of Descemetic deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) in the treatment of advanced keratoconus.

Design

Retrospective, comparative, interventional study.

Methods

This study enrolled eyes affected by keratoconus with preoperative mean keratometry ≥60 diopters (D) that were treated with either Descemetic DALK (30 eyes) or PK (29 eyes) by using always the same corneal diameters (8.00mm recipient; 8.25mm donor cornea) and the same suture technique (10-0 nylon double-running 12-bites continuous suture). The outcome measures were postoperative uncorrected distance visual acuity (UDVA), best-corrected distance visual acuity (CDVA), subjective refractive astigmatism (SRAst), and keratometric astigmatism at 3mm area (SimK), spherical equivalent (SEq).

Results

Postoperative visual acuity significantly improved in both groups. Mean CDVA was higher in the DALK group 3 months (DALK 0.61, PK 0.42, p<0.05), 6 months (DALK 0.69, PK 0.44, p<0.05), and 12 months (DALK 0.72, PK 0.45, p<0.05) postoperatively. However, 6 months after suture removal, CDVA was not statistically different between the two groups (DALK 0.71, PK 0.75, p>0.05). Final SRAst and SimK also were comparable between the two groups (respectively DALK 2.97, PK:2.81, p>0.05; DALK 3.91, PK 2.37, p>0.05). No significant statistical differences were noted for UCVA and SEq data during the entire follow-up period between the two groups.

Conclusion

Both methods of corneal transplantation resulted in a notable enhancement of visual and refractive outcomes in eyes afflicted by advanced keratoconus. Descemetic DALK demonstrated superior visual acuity before suture removal, whereas DALK and PK exhibited comparable results in terms of visual acuity, refractive correction, and keratometric astigmatism after suture removal.

Penetrating Keratoplasty Versus Deep Anterior Lamellar Keratoplasty for Advanced Stage of Keratoconus

PURPOSE

To compare visual acuity, refractive error, and complications after penetrating keratoplasty (PK) vs deep anterior lamellar keratoplasty (DALK) in the management of advanced stage of keratoconus.

DESIGN

Retrospective, comparative, interventional study.

METHODS

This study enrolled 411 consecutive keratoconus eyes with preoperative mean keratometry ≥60 diopters (D) that received either PK (218 eyes) or DALK (193 eyes). The outcome measures were postoperative visual acuity, refraction, complications, and further surgical interventions.

RESULTS

The mean follow-up duration was 77.9±46.5 and 72.9±47.8 months in the PK and DALK groups, respectively (P = .28). Compared with baseline values, postoperative visual acuity and refraction significantly improved in both groups. Postoperative corrected distance visual acuity was 0.18±0.13 and 0.26±0.19 logMAR in the PK and DALK groups, respectively (P < .001). Postoperative spherical equivalent refraction was -2.89±2.89 D after PK and -4.58±3.62 D after DALK (P < .001). Final keratometric astigmatism was comparable between the 2 groups (P = .82). Suture-related complications were observed in 48.6% of the PK eyes and 72.0% of the DALK eyes (P < .001). The incidence of graft rejection was 33.5% after PK and 19.7% after DALK (P = .002). At the last visit, 98.2% of PK grafts and 94.8% of DALK grafts remained clear (P = .06).

CONCLUSION

Both techniques of corneal transplantation led to a significant improvement in the visual and refractive variables in eyes with advanced keratoconus. PK resulted in a better visual acuity and refraction with less suture-related complications compared to DALK. However, PK was associated with a higher rate of graft rejection. The 2 techniques were comparable in terms of graft survival.

Influence of the Postmortem/Storage Time of Human Corneas on the Properties of Cultured Limbal Epithelial Cells

Besides being a powerful model to study the mechanisms of corneal wound healing, tissue-engineered human corneas (hTECs) are sparking interest as suitable substitutes for grafting purposes. To ensure the histological and physiological integrity of hTECs, the primary cultures generated from human cornea (identified as human limbal epithelial cells (hLECs) that are used to produce them must be of the highest possible quality. The goal of the present study consisted in evaluating the impact of the postmortem/storage time (PM/ST) on their properties in culture. hLECs were isolated from the entire cornea comprising the limbus and central cornea. When grown as monolayers, short PM/ST hLECs displayed increased daily doublings and generated more colonies per seeded cells than long PM/ST hLECs. Moreover, hLECs with a short PM/ST exhibited a markedly faster wound closure kinetic both in scratch wound assays and hTECs. Collectively, these results suggest that short PM/ST hLECs have a greater number of highly proliferative stem cells, exhibit a faster and more efficient wound healing response in vitro, and produce hTECs of a higher quality, making them the best candidates to produce biomaterial substitutes for clinical studies.

Penetrating Keratoplasty Versus Deep Anterior Lamellar Keratoplasty in Children and Adolescents With Keratoconus

PURPOSE

To compare the outcomes of penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK) for pediatric keratoconus.

DESIGN

Retrospective comparative interventional case series.

METHODS

This study included consecutive pediatric keratoconus cases (≤18 years of age) who received PK (n=45) or DALK (n=54) in 2 different time periods. Postoperative best spectacle-corrected visual acuity (BSCVA), refraction, and complications were compared between the study groups.

RESULTS

The mean follow-up was 83.3±46.1 and 63.3±45.6 months in the PK and DALK groups, respectively (P = .10). Postoperatively, BSCVA was 0.20±0.19 logMAR in the PK group and 0.26±0.19 logMAR in the DALK group (P = .11), with a BSCVA of ≥20/40 in 91.1% and 83.3% of eyes, respectively (P = .25). Two groups were comparable regarding postoperative refractive outcomes. Graft epitheliopathy and suture-associated complications were more commonly encountered after DALK, which was attributable to the effect of low-quality grafts on the clinical outcomes of DALK. Ten PK eyes (22.2%) and 9 DALK eyes (16.7%) experienced at least 1 episode of graft rejection within 5 years of corneal transplantation (P = .49). Rejection was reversible in 93.1% and 100% of episodes in the PK and DALK groups, respectively (P = .63). At the postoperative year 5, 95.6% of grafts in the PK group and 98.2% in the DALK group remained clear (P = .45).

CONCLUSION

No significant difference was observed in the outcomes between PK and DALK in pediatric keratoconus. Low-quality donor tissues in DALK increased the incidence of graft epithelial problems and suture-related complications as compared to PK.

Comparison of penetrating keratoplasty and deep anterior lamellar keratoplasty in keratoconus eyes with vernal keratoconjunctivitis

Purpose:

The purpose of the study is to compare outcomes after penetrating keratoplasty (PK) against deep anterior lamellar keratoplasty (DALK) for keratoconus in patients with vernal keratoconjunctivitis (VKC).

Methods:

Keratoconic patients with VKC who received PK (n = 55, group 1) or DALK (n = 62, group 2) were retrospectively enrolled. The Student’s t test, Mann–Whitney test, Fisher’s exact test, chi-square test, and Kaplan–Meier survival curve were used to compare outcomes between the groups.

Results:

The follow-up period was 59.4 ± 44.1 and 62.4 ± 38.9 months in groups 1 and 2, respectively (p = 0.70). Postoperative best spectacle-corrected visual acuity was 0.24 ± 0.18 and 0.29 ± 0.19 logMAR, respectively (p = 0.13). Graft rejection occurred in 34.6% and 25.8% of eyes in groups 1 and 2, respectively (p = 0.30). Groups 1 and 2 were comparable in the rates of cataract (3.6% and 12.9%, respectively, p = 0.07) and high intraocular pressure (3.6% and 8.1%, respectively, p = 0.31). Compared with the eyes with inactive VKC, PK eyes that experienced postoperative disease reactivation had a higher rate of suture abscesses (10.9% versus 50.0%, respectively, p = 0.01) and suture-tract vascularization (6.5% versus 33.3%, respectively, p = 0.03). Similarly, disease reactivation significantly increased suture abscesses from 27.3% to 51.7% (p = 0.03) and suture-tract vascularization from 18.2% to 49.6% (p = 0.005) in the DALK group. The graft survival rates were 95.3% in group 1 and 87.9% in group 2 at the 4-year follow-up, with mean durations of 14.4 and 11.1 months, respectively (p = 0.20).

Conclusion:

The results indicate no difference in outcomes between PK and DALK for keratoconus in patients with VKC. Postoperative VKC reactivation increased the rate of suture-related problems after both techniques of keratoplasty.

Sinasol versus Optisol-GS for cold preservation of human cornea: a prospective ex vivo and clinical study

To compare ex vivo results of donor corneas maintained in Sinasol with those stored in Optisol-GS and reporting clinical outcomes of grafted Sinasol-versus Optisol-GS-stored corneas. In phase I, paired donor corneas were maintained in Sinasol or Optisol-GS. Afterward, the corneas were subjected to slit-lamp biomicroscopic and specular microscopic examinations on days 1 and 7, and then to trypan blue staining on day 7. The same examinations were performed on the corneas that were kept in Sinasol or Optisol-GS for 14 days. In phase II, the post-operative reports of 72 consecutive corneal transplantations were recorded using Sinasol- or Optisol-GS-preserved corneas. In phase I, 128 corneas from 64 donors and 59 corneas from 33 donors were investigated for 7 and 14 days, respectively. The EC indices were comparable between the groups at the measurement periods. The EC losses over 7 and 14 days were 3.7% and 19.9% in Sinasol against 4.6% and 20.8% in Optisol-GS. Although fair quality corneas were more common in Optisol-GS group after 7 (P = 0.04) and 14 days (P = 0.034), changes of stromal edema, Descemet's fold, and other quality ratings during 14 days were not different between the groups. In phase II, all the transplanted corneas were postoperatively clear with no adverse reactions. The overall results indicate that Sinasol is a safe, effective, and affordable intermediate cold storage medium for preservation of corneas.

Pseudophakic corneal donor tissue in Descemet membrane endothelial keratoplasty (DMEK): implications for cornea banks and surgeons

Objective

Increasingly, cornea banks are recovering donor tissue from pseudophakic donors. Little is known about their suitability for Descemet membrane endothelial keratoplasty (DMEK) surgery in terms of endothelial cell density (ECD) and preparation failure.

Methods and Analysis

We explored ECD during donor tissue preparation in 2076 grafts. Preparation failure was analysed in 1028 grafts used in DMEK surgery at our clinic. To monitor ECD and functional results, we matched 86 DMEK patients who received pseudophakic donor grafts with similar recipients of phakic donor grafts and followed them up for 36 months.

Results

At recovery, mean ECD in pseudophakic donor grafts was 2193 cells/mm² (SD 28.7) and 2364 cells/mm² (SD 15.7) in phakic donor grafts (p<0.001). After cultivation, the difference increased as pseudophakic donor grafts lost 14% of ECD while phakic lost only 6% (p<0.001). At transplantation, mean ECD in pseudophakic donor grafts was 2272 cells/mm² (SD 250) and 2370 cells/mm² (SD 204) in phakic donor grafts (p<0.001). After transplantation, the difference in ECD increased as pseudophakic donor grafts lost 27.7% of ECD while phakic donor grafts lost only 13.3% (p<0.001). The risk of preparation failure in pseudophakic donor grafts was higher than in phakic donor grafts (OR 4.75, 95% CI 1.78 to 12.67, p=0.02). Visual acuity increased in both groups similarly.

Conclusions

Pseudophakic donor grafts have a lower ECD, are more prone to endothelial cell loss during recovery and surgery and are associated with a higher risk of preparation failure. Cornea banks and surgeons should consider this in the planning of graft preparation and transplantation.

An analysis of factors associated with graft topographic outcomes after deep anterior lamellar keratoplasty

PURPOSE

To investigate the correlations between preoperative, operative, and postoperative factors and corneal graft topographic parameters after deep anterior lamellar keratoplasty (DALK) performed in keratoconus-affected eyes.

METHODS

This prospective, interventional study enrolled 44 eyes. Graft topographic parameters, including keratometric astigmatism and the surface regularity index (SRI), were assessed after complete suture removal. Univariate analyses were used to evaluate the effects of preoperative factors (donor quality, donor and recipient age, keratoconus severity), operative factors (graft size, donor button roundness, roundness and centration of the donor-recipient junction), and postoperative factors (time point of suture removal) on postoperative topographic parameters.

RESULTS

The roundness of the donor-recipient junction after complete suture removal had a significant association with the roundness of the donor button after trephination (P = 0.04) and the amount of graft decentration relative to the limbus (P = 0.03). A significant correlation was found between the value of graft decentration relative to the limbus and postoperative keratometric astigmatism (P = 0.001) and between the roundness of the donor-recipient junction and the postoperative SRI (P = 0.02). The flat axis of the keratometric astigmatism and the longer axis of the graft lay in the direction of graft displacement. Other investigated factors had no significant association with postoperative topographic indices.

CONCLUSION

Graft displacement relative to the limbus and roundness of the donor-recipient junction were the main predictors of graft astigmatism and regularity, respectively, after DALK. Noncircularity of the donor button after trephination could increase the graft surface irregularity indirectly by influencing the roundness of the surgical wound.

Appropriate stage of Descemet membrane removal during donor preparation in deep anterior lamellar keratoplasty

PURPOSE

To investigate the appropriate surgical stage for Descemet membrane (DM) removal during donor preparation in deep anterior lamellar keratoplasty (DALK).

METHODS

This study included 83 corneoscleral buttons that were used for DALK. The donor DM was removed randomly either before (group 1; 43 eyes) or after (group 2; 40 eyes) trephination. The time required for DM removal was recorded, and the geometric properties of cut buttons were evaluated after trephination. The intraoperative video recordings were reviewed to determine if the dissections were performed at the stroma-DM plane as it was intended. The time needed to remove the DM, the rate of correct dissection at the intended stroma-DM plane, and the roundness and precision of the donor cuts were compared between the groups.

RESULTS

The two groups were comparable in donor characteristics, including age, quality of the tissue, and trephination size. Time spent to remove DM was significantly shorter in group 1 (68.9 ± 48.2 s) than group 2 (117.7 ± 52.7 s, P = 0.001). DM stripping was performed incorrectly in 2 corneas (4.7%) in group 1 and in 12 corneas (30%) in group 2 (P = 0.01). No difference was found between the groups in the roundness and precision of donor button cuts.

CONCLUSIONS

DM removal before trephination did not detrimentally affect the geometric properties of punched donor tissues. When DM stripping was performed before trephination, the donor tissue was less traumatized and posterior graft surface was more likely to be regular; therefore, it is advisable to remove DM before trephination during donor preparation for DALK.

Approaches toward enhancing survival probability following deep anterior lamellar keratoplasty

The greatest advantage of deep anterior lamellar keratoplasty over full-thickness corneal transplantation is the elimination of graft failure caused by endothelial rejection. Despite this advantage, a deep anterior lamellar keratoplasty graft can fail because of several factors, such as complications related to the donor-recipient interface, graft epithelial abnormalities, graft vascularization, stromal graft rejection, and recurrence of herpetic keratitis. Increased deep anterior lamellar keratoplasty graft survival is mainly built upon optimization of the ocular surface to provide a hospitable environment for the graft. Any predisposing factors for graft epithelial abnormalities, corneal neovascularization, and preexisting vernal keratoconjunctivitis should be identified and treated preoperatively. Prompt recognition and appropriate treatment of interface-related complications and stromal graft rejection usually result in good anatomic outcomes, with no detrimental effects on vision.

Peripheral Hypertrophic Subepithelial Opacities of Corneal Grafts After Deep Anterior Lamellar Keratoplasty

PURPOSE

To investigate possible underlying etiologies of the development of peripheral graft hypertrophic subepithelial opacities (PGHSO) and to evaluate the effects of these opacities on visual outcomes after deep anterior lamellar keratoplasty (DALK).

METHODS

This prospective, interventional case series enrolled 29 eyes with keratoconus that underwent DALK and developed PGHSO (group 1). The control group consisted of 32 eyes with keratoconus that underwent DALK during the same period and had a clear graft at the final examination (group 2). Possible underlying risk factors for the development of PGHSO were investigated, and postoperative refractive and topographic outcomes were compared between the 2 study groups.

RESULTS

Eyes of group 1 had well-defined elevated peripheral subepithelial opacities of the corneal graft, originating from the donor-recipient junction. The central 4-mm area of the graft was clear in all eyes of this group. Compared with the controls, group 1 had flatter grafts at postoperative month 1 and a longer time interval from surgery to initial suture removal. The 2 study groups were comparable in other investigated factors, including the severity of keratoconus, surgical technique, duration of topical steroid use, and donor quality. No significant differences were observed between the case and control groups in postoperative visual acuity and graft surface regularity.

CONCLUSIONS

Graft flattening during the early postoperative period and prolonged time interval from surgery to initial suture removal might be factors predisposing to the development of PGHSO. This complication did not affect postoperative visual outcomes when the central 4-mm area of the graft remained clear.

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.

Geometric Properties of Donor Corneas After Mechanical Trephination in Deep Anterior Lamellar Keratoplasty

PURPOSE

To evaluate the geometry of donor corneal buttons after mechanical trephination and to determine whether there were any possible variables that could influence the accuracy of cutting corneal buttons in deep anterior lamellar keratoplasty.

METHODS

This cross-sectional study included 85 sclerocorneal buttons that were transplanted during deep anterior lamellar keratoplasty. Donor corneas were punched from the posterior surface. Photographs that most clearly represented the entire edges of the donor corneas were taken from the punched corneas and systematically analyzed using ImageJ software. The univariate analyses were used to investigate the influence of potential variables on the precision and roundness of the donor cut.

RESULTS

The epithelial side of the grafts was significantly larger than the posterior side in diameter, perimeter, and area. The perimeter and area of the donor posterior surface and the trephine used for punching the grafts were the same, whereas the epithelial side had a significantly larger perimeter and area than those of the trephine. Graft roundness varied from 0.78 to 1.0 at the epithelial side and from 0.77 to 1.0 at the posterior side. The roundness of the scleral spur, which represented the shape of the donor cornea, was identified as the main predictor of the roundness of the donor cut (P < 0.001).

CONCLUSIONS

The donor buttons after mechanical trephination from the posterior surface may not be circular and of the intended diameter; the epithelial surface dimensions were significantly larger than the posterior surface and trephine dimensions. The roundness of the punched graft was primarily affected by the roundness of the cornea before trephination.

[Influence of the donor age on graft survival : Is the demographic change also important for corneal tissue donation?]

The success of corneal transplantation highly depends on the quality of the used graft. Various factors play a crucial role such as a perfect stroma without optically relevant, centrally located cloudiness or changes (e. g. scars) or an adherent Descemet membrane. One of the most important parameters is the quality of the endothelial cell layer with a sufficiently large endothelial cell count. An open question is so far whether the donor age affects corneal quality and therefore has an impact on the success of transplantation. A comprehensive review of the available literature revealed that a large amount of scientific data on the influence of donor age exist to answer this question. In a variety of studies, no significant dependence of graft quality of donor age could be detected. Rather the studies prove that graft survival depends primarily on the state of the endothelial cell layer, and postoperative endothelial cell loss must be considered as a major cause of graft failure. Extensive quality assurance procedures in tissue preparation and cornea processing in the eye banks in Germany (Europe) ensures that only corneas with tested high quality are allocated for transplantation regardless of the donor age. Against the background of an aging population, the use of grafts from older donors should not be waived.

Impact of donor graft quality on deep anterior lamellar Keratoplasty (DALK)

Background

To evaluate main features of donor tissue that may influence clinical outcome or complication rate after deep anterior lamellar keratoplasty (DALK).

Methods

Donor tissue parameters of 84 consecutive corneal donor grafts used for big-bubble DALK surgery between June 2011 and December 2014 in 84 eyes of 84 patients with disorders of anterior corneal stroma were correlated to clinical outcome parameters of recipient eyes 12 months after surgery and 3 months after total suture removal. Main donor tissue parameters included age), post-mortem time, overall preservation time, preservation time after split and prior to transplantation, and preservation technique. Clinical outcome parameters included best spectacle corrected visual acuity (BSCVA), central corneal thickness (CCT), endothelial cell density (ECD) and complication rates. Pearson’s correlation, linear regression analysis for clinical outcome parameter and logistic regression analysis for postsurgical complication rates were applied.

Results

Corneal donors were mean aged 67.4 ± 12.5 years with a post-mortem time of 20.7 ± 14.7 h and ECD of 2641.0 ± 362.8 cells/mm². Overall preservation time was 16.3 ± 6.3 days. Recipients showed mean BSCVA 12 months postoperatively of 0.60 ± 0.36 logMAR, endothelial cell loss was 4 ± 16%, and central corneal thickness was 571.7 ± 54.2 μm. 3 months after total removal of sutures, BSCVA was 0.20 ± 0.10 logMAR, endothelial cell loss was 17 ± 24%, and central corneal thickness was 590.9 ± 55.5 μm. Loosening of sutures occurred in 20%, and Descemet detachment in 16%. None of the clinical outcome parameters or complication rate after DALK showed a significant association with donor tissue parameters.

Conclusions

Donor corneas, independent of excision techniques or preservation method, with donor age ≤ 88 years, post-mortem time ≤ 63 h, overall preservation time ≤ 14 days for cold storaged donor tissue and ≤35 days for organ culture, and preservation time after split prior to grafting ≤96 h, seem to be applicable as safe donor tissue for DALK surgery.

Comparison of outcomes and complications of deep anterior lamellar keratoplasty and penetrating keratoplasty performed in a large group of patients with keratoconus

PURPOSE

To compare visual acuity, refraction, topography, and complications of deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PKP) performed in patients with keratoconus (KCN).

METHODS

In this retrospective interventional non-randomized clinical study, patients with moderate to severe KCN that underwent either PKP or DALK for optical corrections were enrolled. The final outcome analysis was performed after complete suture removal for both groups of patients. Best corrected visual acuity, spherical equivalent, refractive cylinder, average keratometry, corneal astigmatism, and endothelial cell density as well as early and late complications such as cataract, glaucoma, corneal edema, elevated intraocular pressure without visual field defect or optic disk changes, rejection, loose suture, and re-suturing were compared.

RESULTS

Two hundred and seven eyes were enrolled: 108 eyes underwent DALK, and 99 eyes underwent PKP for keratoconus. The mean follow-up time was 28.06 ± 12.62 months for DALK group and 29.29 ± 12.71 months for PKP. The study groups demonstrated comparable final outcome in terms of best corrected visual acuity: 0.25 ± 0.22 LogMAR and 0.28 ± 0.24 LogMAR (p = 0.415), spherical equivalent: -4.80 ± 4.55D and -3.58 ± 3.58D (p = 0.067), refractive cylinder: -3.37 ± 2.00D and -4.00 ± 2.15D (p = 0.061), average keratometry: 45.51 ± 2.30D and 44.85 ± 2.36D (p = 0.077), corneal astigmatism: 4.89 ± 3.07D and 4.63 ± 2.61D (p = 0.569) in DALK (n = 85) and PKP (n = 72), respectively. However, the postoperative endothelial cell density in DALK (n = 61) 2250 ± 450 cell/mm² differs significantly from it in PKP (n = 55) 1795 ± 616 cell/mm² p < 0.001. Eyes that had DALK (n = 99) had significantly more risk of loose suture (RR 5.2) and re-suturing (RR 3.6) than PKP (n = 108). However, the risk of cataract following DALKs was less than PKP (OR 0.4).

CONCLUSION

The vision, refractive error, and corneal astigmatism following DALK and PKP were comparable; however, DALK had lower incidence of long-term complications.

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.

Donor cornea quality used for penetrating keratoplasty vs deep anterior lamellar keratoplasty

Deep anterior lamellar keratoplasty (DALK) has recently been introduced as an alternative procedure to penetrating keratoplasty (PK) for corneal pathologies not affecting the corneal endothelium. DALK does not rely on donor endothelium and requires less rigid criteria for donor corneal tissue quality. Therefore, DALK makes it possible to use donor corneas deemed unsuitable for PK. Furthermore, lamellar keratoplasty allows acellular corneal tissue to be transplanted. As a result, long-term preservation techniques are being revisited to increase the availability of donor corneas and subsequently alleviate constraints of availability, cost, storage, and transportation in many countries. The recent alterations in corneal transplantation techniques and hence the type of donor cornea tissues used for each technique, may require corneal surgeons and eye banks to reevaluate their selection criteria. The purpose of this systematic review is to present an updated analysis on the type and quality of donor corneas used for PK and DALK, assess the influence of donor and eye bank factors on the quality of donor corneas, and determine whether any of these donor factors affect clinical outcomes, complications, and graft survivals.