Corneal endothelial specular microscopy following deep lamellar keratoplasty with lyophilised tissue

Modified big bubble technique for deep anterior lamellar keratoplasty in keratoconus

We describe a modified technique for deep anterior lamellar keratoplasty with three modifications in big bubble pneumodissection technique; including two staged stromal trephination to avoid inadvertent full-thickness trephination, deep bevel-up needle air injection for better visualization and deeper air injection and, vicoseperation by refilling the pre-Descemet space with a viscoelastic after removing the air bubble for safe removal of the deep stromal layers. Patients with advanced keratoconus underwent deep anterior lamellar keratoplasty with pneumodissection by two-staged trephination followed by bevel-up needle deep air injection and viscoseperation. The big bubble was successfully formed in all cases and there was no case with the rupture of the Descemet's membrane (DM) during air injection or baring of DM.

Corneal aberrations, densitometry on scheimpflug imaging, and visual acuity after deep anterior lamellar keratoplasty

PURPOSE

To evaluate visual acuity, corneal aberrations, and densitometry post deep anterior lamellar keratoplasty (DALK).

METHODS

Twenty-five eyes of 25 patients who underwent DALK for corneal stromal diseases with normal endothelium were enrolled in a prospective interventional study. Evaluation for corneal aberrations and densitometry postoperatively was performed using Scheimpflug imaging at 6 months. Anterior Segment Optical Coherence Tomography (ASOCT) was done for host-graft morphology. Correlation analysis of postoperative best-corrected visual acuity with corneal aberrations and corneal densitometry (CD) was performed.

RESULTS

Big bubble deep anterior lamellar keratoplasty (BB-DALK) was successful in 18 patients, while 7 eyes underwent manual dissection due to failed BB (Big Bubble) technique. The mean BSCVA was 1.35 ± 0.46 logMAR units pre-operatively which improved to 0.36 ± 0.19 logMAR units post DALK at 6 months (P < 0.001). The mean Root Mean Square (RMS) (μm) of the magnitude of total corneal aberrations, HOA and LOA from central 6mm zone of cornea were 14.6 ± 9.2, 4.7 ± 2.9, and 13.8 ± 8.8, respectively. The mean anterior (120μm), central and posterior corneal (60μm) densitometry in 0-2mm zone were 25.8 ± 7.7 GSU, 18.7 ± 4.16 GSU and 10.09 ± 3.9 GSU respectively. A statistically significant correlation of postoperative residual stromal bed thickness, total corneal HOA, LOA, total corneal aberrations, HOA front and posterior corneal densitometry (0-2mm zone) with postoperative BSCVA was found.

CONCLUSION

Though there is a significant improvement in BSCVA after DALK, the quality of vision in terms of aberrometry and densitometry is suboptimal, especially in cases undergoing manual DALK compared to those undergoing big bubble formation.

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.

Lamellar Keratoplasty for Advanced Keratoconus

Ectatic corneal diseases are a group of disorders resulting in progressive corneal steepening and thinning. Keratoconus, keratoglobus, pellucid marginal degeneration, post-keratorefractive ectasia, and corneal graft ectasia are the types of corneal ectasia. Early diagnosis with appropriate diagnostic tools can help prevent progression, eliminating the need for corneal transplantation. Lamellar or full thickness corneal transplantation are the treatment options for advanced diseases. Although the visual outcomes of penetrating keratoplasty are comparable to anterior lamellar keratoplasty (ALK) especially in keratoconus, ALK is the preferred treatment of choice considering benefits including reduced graft rejection, less long-term complications, and better graft survival. This article reviews the various surgical techniques in ALK with its clinical outcomes in advanced keratoconus.

Comparison of Endothelial Cell Loss following the Big Bubble versus the Microbubble Incision Technique during Deep Anterior Lamellar Keratoplasty in Eyes with Keratoconus

Introduction. Deep anterior lamellar keratoplasty (DALK) is now becoming an increasingly popular surgical technique in treating corneal stromal pathologies with healthy endothelium. Several advantages of DALK over penetrating keratoplasty (PKP) have been described such as maintenance of globe integrity, absence of endothelial rejection, and a low rate of chronic endothelial cell loss (ECL). ECL following PKP results in 50% cell loss after 2 years from the estimated graft endothelial cell density (ECD). Although there are several reports confirming that ECL following DALK is similar to the physiologic cell loss 2 years after surgery, few reports discussed the surgically induced ECL due to difficulty in preoperative imaging of ECD. Materials and Methods. This prospective, interventional study included 20 eyes of 20 patients, who underwent DALK surgery. 11 eyes underwent DALK using the big bubble technique, while 9 eyes underwent the microbubble technique. Postoperative evaluation was done 3 months after surgery and included best spectacle corrected visual acuity (BSCVA), keratometric readings, and refraction measured using an autokeratorefractometer (Topcon KR800, Japan) and endothelial cell density (ECD) using noncontact specular microscopy (Nidek CEM-530, Japan). Results. Regarding postoperative parameters such as postoperative logMAR visual acuity, postoperative mean K, and postoperative K max, there was no statistical difference found between both groups ( $P=0.754$ , $P=0.119$ , and $P=0.970$ , respectively). Regarding change in specular endothelial cell density and percent change in the specular endothelial cell density, again there was no statistical difference between both groups with $P=0.057$ and $P=0.126$ , respectively (significance defined as $P<0.05$ ). Conclusion. ECD is not affected by failure of the big bubble to form and continuing DALK via the microbubble technique.

A review of long-term corneal preservation techniques: Relevance and renewed interests in the COVID-19 era

The growth of eye banking in India was showing positive trends until the nation was hit by unprecedented times as a result of the COVID-19 pandemic. The impact of this has led to a downward spiraling in eye banking activities globally. Several measures had to be implemented to tide over the crisis and strategies planned for future to prepare for the needs of corneal transplantation. While eye banks in India have been practicing short- term and intermediate storage preservation media, there is a definite need to evolve other methods of very long-term preservation. This review discusses various methods of long term corneal preservation, their relevance and applications in the present times. We reviewed relevant medical literature in English from PUBMED with the key words “Corneal preservation”, “Cryopreservation”, “Glycerol preservation”, Gamma Irradiation”, “Eye Banking” ,”COVID-19”.

Optical Coherence Tomography Guided Robotic Needle Insertion for Deep Anterior Lamellar Keratoplasty

OBJECTIVE

Deep anterior lamellar keratoplasty (DALK) significantly reduces the post-transplantation morbidity in patients eligible for partial-thickness cornea grafts. The popular "big bubble" technique for DALK is so challenging, however, that a significant fraction of corneal pneumodissection attempts fail for surgeons without extensive DALK-specific experience, even with previous-generation cross-sectional optical coherence tomography (OCT) guidance. We seek to develop robotic, volumetric OCT-guided technology capable of facilitating or automating the difficult needle insertion step in DALK.

METHODS

Our system provides for real-time volumetric corneal imaging, segmentation, and tracking of the needle insertion to display feedback for surgeons and to generate needle insertion plans for robotic execution. We include a non-automatic mode for cooperative needle control for stabilization and tremor attenuation, and an automatic mode in which needle insertion plans are generated based on OCT tracking results and executed under surgeon hold-to-run control by the robot arm. We evaluated and compared freehand, volumetric OCT-guided, cooperative, and automatic needle insertion approaches in terms of perforation rate and final needle depth in an ex vivo human cornea model.

RESULTS

Volumetric OCT visualization reduces cornea perforations and beneficially increases final needle depth in manual insertions by clinically significant amounts. Our automatic robotic needle insertion techniques meet or exceed surgeon performance in both needle placement and perforation rate.

CONCLUSION

Volumetric OCT is a key enabler for surgeons, although robotic techniques can reliably replicate their performance.

SIGNIFICANCE

Robotic needle control and volumetric OCT promise to improve outcomes in DALK.

Use of Fibrin Glue in the Management of Descemet Membrane Perforation during Deep Anterior Lamellar Keratoplasty

PURPOSE

To describe the use of fibrin glue to seal Descemet membrane (DM) microperforation and macroperforation during deep anterior lamellar keratoplasty (DALK).

METHODS

A retrospective chart review was performed on patients who had DM perforation managed by fibrin glue during DALK at King Khaled Eye Specialist Hospital (KKESH) between June 2014 and February 2019.

RESULTS

One thousand two hundred and eighty-eight DALK surgeries were performed at KKESH during the study period. Fibrin glue was used to seal DM perforations in four cases of DALK for keratoconus.

CONCLUSION

Fibrin glue is an effective method to seal DM microperforations and macroperforations during DALK, which reduces the rate of conversion to penetrating keratoplasty (PK), preserving the advantage of DALK over PK.

Breathing Life into the Cadaver: Introducing Air Dissection As a New Teaching and Dissecting Method for the Venous System

Air insufflation has been used for various surgical procedures such as during laparoscopy. We hypothesized that the use of pressurized air might enable cadaveric dissection to differentiate smaller veins better than traditional dissection techniques. In three fresh-frozen cadavers, the inferior vena cava (IVC) and right or left femoral veins were exposed just distal to the inguinal ligament and a needle placed into one of them. Pressurized air was then placed into the cannulated femoral vein using an air compressor. In all specimens, the IVC and most of its tributaries, both left and right sides, were clearly insufflated. When the IVC was traced superiorly by resecting the diaphragm through the caval foramen, the right atrium and ventricle were also found to be dilated. Additionally, venous variants that would have not been obvious without dilatation of the IVC were identified. Air dissection of the venous system in fresh-frozen cadavers aids in anatomical dissection. Such a model might also serve as a surgical training model and teaching tool as it better mimics life-like anatomy and physiology. We term this technique "cadaveric air dissection." Clin. Anat. 32:566-572, 2019. © 2019 Wiley Periodicals, Inc.

Deep anterior lamellar keratoplasty: A surgeon's guide

Purpose

To review and highlight important practical aspects of deep anterior lamellar keratoplasty (DALK) surgery and provide some useful tips for surgeons wishing to convert to this procedure from the conventional penetrating keratoplasty (PK) technique.

Methods

In this narrative review, the procedure of DALK is described in detail. Important pre, intra, and postoperative considerations are discussed with illustrative examples for better understanding. A comprehensive literature review was conducted in PubMed/Medline from January 1995 to July 2017 to identify original studies in English language regarding DALK. The primary endpoint of this review was the narrative description of surgical steps for DALK, its pitfalls, and management of common intraoperative complications.

Results

A standard DALK procedure can be successfully performed taking into consideration factors such as age, ophthalmic co-morbidities, status of the crystalline lens, retina, and intraocular pressure. Careful trephination and dissection of the host cornea employing appropriate technique (such as big bubble technique, manual dissection, visco-dissection, etc.) suitable for the specific case is important to achieve good postoperative outcomes. Prompt identification of intraoperative complications such as double bubble, micro and macroperforations, etc. are vital to change the management strategies.

Conclusion

Although there is a steep learning curve for DALK procedure, considering details and having insight into the management of intraoperative issues facilitates learning and reduces complication rates.

Systematic review comparing penetrating keratoplasty and deep anterior lamellar keratoplasty for management of keratoconus

AIM

Perception of reduced incidence of graft rejection after deep anterior lamellar keratoplasty (DALK) has attracted many surgeons towards this technique in keratoconus. This review aims to compare the visual, refractive and graft outcomes after penetrating keratoplasty (PK) and DALK for keratoconus.

METHODS

Electronic searches of PubMed, MEDLINE, EMBASE, Latin American and Caribbean Health Sciences Literature database (LILACS), metaRegister of Controlled Trials (mRCT), ClinicalTrial.gov and the WHO International Clinical Trials Registry Platform (ICTRP) were performed. We included randomized control trials (RCTs) and comparative studies to assess primary and secondary outcomes after PK and DALK in eyes with keratoconus. Primary outcome was best-corrected visual acuity (BCVA) LogMAR at ≥6 months. Secondary outcomes included number of patients with BCVA≥0 LogMAR, uncorrected visual acuity (UCVA) LogMAR, spherical equivalent (SE), refractive and keratometric astigmatism, endothelial cell density (ECD) cell/mm², graft rejection and graft survival.

RESULTS

Eighteen studies (including 2 RCTs) compared DALK (965 eyes) and PK (2402 eyes) for keratoconus. There was strong evidence through RCTs suggesting better LogMAR BCVA at ≥6 months and better LogMAR UCVA with PK; reduced refractive astigmatism and rejection with DALK and no difference in SE and keratometric astigmatism. Moreover, there was weak evidence to suggest better BCVA≥0 LogMAR after PK and no difference in ECD between the two techniques.

CONCLUSIONS

Despite the popularity of DALK amongst corneal surgeons for keratoconus, there is a paucity of high quality RCTs. The existing limited evidence confirms reduced rejection and refractive astigmatism with DALK but better visual outcomes with PK. Internationally agreed data sets and follow-up protocol are warranted.

Visual Outcomes of Successful versus Failed Big-Bubble Deep Anterior Lamellar Keratoplasty for Keratoconus

PURPOSE

To compare the visual outcomes of deep anterior lamellar keratoplasty (DALK) for keratoconus with and without successful big-bubble formation.

METHODS

In this retrospective comparative study, a total of 289 consecutive eyes from 257 patients underwent DALK using the big-bubble technique. In cases where the big bubble could not be accomplished, manual stromal dissection down to Descemeton membrane (DM) was performed using a crescent knife. Visual acuity and refractive outcomes were compared between the bare DM group (Group 1) and manual dissection group (Group 2).

RESULTS

A bare DM was successfully achieved in 229 (79.2%) eyes and manual dissection was performed in 60 (20.8%) eyes. The study groups were comparable in terms of age (P = 0.79), preoperative best-spectacle corrected visual acuity (BSCVA) (P = 0.15), and follow-up duration (P = 0.73). Postoperative BSCVA was significantly better in Group 1 than in Group 2 throughout follow-up (P < 0.05). In Group 2, BSCVA was significantly lower in eyes with advanced keratoconus as compared to those with moderate keratoconus (P = 0.007). At final follow-up, BSCVA ≤ 0.30 logarithm of minimum angle of resolution (logMAR) was achieved in 82.1% of eyes in Group 1 versus 54.5% of eyes in Group 2 (P < 0.001). Groups 1 and 2 were comparable in terms of postoperative spherical equivalent refractive error (P = 0.61) and keratometric astigmatism (P = 0.39).

CONCLUSION

Retention of the posterior corneal stroma which occurs with manual dissection during failed big bubble formation in DALK is associated with lower visual acuity as compared to achieving a bare DM.

Factors influencing big-bubble formation during deep anterior lamellar keratoplasty in keratoconus

PURPOSE

To investigate recipient and operative factors that can influence the rate of achieving a bare Descemet's membrane (DM) during deep anterior lamellar keratoplasty (DALK) for keratoconus.

MATERIALS

In this retrospective comparative study, a total of 290 (153 right) consecutive eyes from 257 (179 male) keratoconus-affected patients who underwent DALK with the big-bubble technique were enrolled. Univariate analyses and multiple logistic regressions were used to investigate factors including patient age and sex, family history of keratoconus, history of contact lens wear or vernal keratoconjunctivitis, the presence of Vogt's striae or superficial stromal opacities, keratometric readings, corneal diameter, central and peripheral corneal thickness, anterior chamber depth, vitreous length, and trephination size, which could predict achievement of a bare DM.

RESULTS

The surgery was completed as a DALK in 289 of 290 eyes, and a bare DM was successfully achieved in 229 (79.2%) eyes. The recipient sex and trephination size significantly influenced the success rate of big-bubble formation. Females had decreased odds of achieving a bare DM by 0.44 times (p=0.02). For each 0.1 mm increase in the trephination size, the odds of a successful big-bubble formation increased by 1.36 times (p=0.03). Other investigated factors did not significantly influence the rate of achieving a bare DM.

CONCLUSIONS

The rate of successful big-bubble formation was 79.2% in keratoconus. Among the different factors, recipient sex and trephination size significantly influenced this rate. Females had a lower probability of big-bubble formation, and a large trephination size was associated with an increase in the probability of achieving a bare DM.

Deep anterior lamellar keratoplasty in the management of keratoconus

Advanced cases of keratoconus often require surgical intervention to restore corneal anatomy and improve eyesight. Penetrating keratoplasty (PK) although commonly performed has potential risk of immunological rejection and is now no longer automatically the first choice of surgery. DALK procedures have evolved, which allows surgical replacement of recipient's corneal stroma, leaving behind healthy descemet membrane (DM) and endothelium. This reduces the risk of allograft endothelial rejection and late graft failure. In recent times, DALK techniques have led to significant improvements in visual outcome and current results are comparable to PK. Big bubble technique of DALK has become the most popular among the various surgical techniques described. Manual near DM DALK also gives good outcome although the visual recovery is often delayed. Future integration of femtosecond laser technology along with diagnostic imaging technology is likely to further improve outcomes of DALK in keratoconus.

Donor Descemet-off versus Descemet-on deep anterior lamellar keratoplasty: a confocal scan study

PURPOSE

To compare confocal features of grafts following deep anterior lamellar keratoplasty (DALK) using a donor without Descemet membrane (DM) versus a full-thickness donor with intact DM and endothelium.

METHODS

This retrospective comparative study examined 45 eyes from patients with keratoconus who underwent DALK using the big-bubble technique. The big-bubble technique yielded a bared DM in all keratoconic eyes. Twenty-seven eyes received tissue from a donor without DM (group 1), while 18 received tissue from a full-thickness donor with an intact DM and endothelium (group 2). A group of normal eyes (n = 28, group 3) served as controls. Confocal microscopy was used to determine keratocyte density, explore the donor-recipient interface including clarity and reflectivity, evaluate endothelial cell density and morphology, as well as measure interface depth and central corneal thickness.

RESULTS

Mean follow-up duration was 20.2 ± 8.6 months and 29.6 ± 17.0 months in groups 1 and 2, respectively (p = 0.13). Confocal scan demonstrated that the keratocyte profiles and distribution were more similar to normal corneas in group 2. Significantly more severe interface haziness was observed when donor DM and endothelium was retained (mean interface reflectivity value of 102.7 ± 22.1 versus 161.7 ± 30.0 light reflectance units in groups 1 and 2, respectively, p&lt;0.001).

CONCLUSIONS

Graft cellular profiles and healing response at the donor-recipient interface can be profoundly affected depending on whether donor DM and endothelium is removed or retained.

Donor cornea preparation in partial big bubble deep anterior lamellar keratoplasty

Background

The purpose of this paper is to describe a technique of donor cornea preparation to ensure good graft-host apposition in incomplete big bubble deep anterior lamellar keratoplasty.

Methods

Following a partial-thickness trephination, manual dissection and excision of corneal stroma was performed. Anwar’s big-bubble technique involving a deep stromal air injection was then initiated. However, the big bubble could not extend to the trephination edge and the peripheral residual corneal stroma could not be removed. Donor cornea preparation involving trimming of the posterior lip of the corneal button was then performed and good graft-host apposition was obtained without graft over-ride.

Results

We performed peripheral donor cornea trimming prior to allograft placement in order to ensure good graft-host apposition. Postoperatively, best-corrected visual acuity in both eyes was 6/7.5.

Conclusion

Donor cornea preparation involving trimming of the posterior lip of the corneal button is a useful technique in instances where the big bubble does not extend to the trephination edge and ensures good graft-host apposition.

Comparison between femtosecond laser mushroom configuration and manual trephine straight-edge configuration deep anterior lamellar keratoplasty

AIM

To compare outcomes and complications of femtosecond laser (FSL) mushroom configuration and manual trephine (MT) straight-edge configuration deep anterior lamellar keratoplasty (DALK).

METHODS

A cohort of 19 consecutive eyes that underwent FSL DALK was compared with 19 consecutive eyes that underwent MT DALK. Surgery was performed for eyes with keratoconus, corneal ectasia and scarring. Patient demographics, best-corrected visual acuities (BCVAs), refraction and complications were compared.

RESULTS

Groups were comparable for age, gender and preoperative BCVA. Rates of intraoperative and postoperative complications were low and comparable between the groups. These included intraoperative Descemet's membrane (DM) perforation which did not require conversion to penetrating keratoplasty; stromal rejection successfully treated with topical steroids; postoperative DM detachment; delayed epithelial healing and increased intraocular pressure which resolved with topical anti-glaucoma drops. At 3 months, the mean BCVA was significantly better in the FSL group compared with the MT group (p=0.00002). At 6 months and 1 year, there was no significant difference between mean BCVA between the two groups. Mean spherical equivalent, cylindrical astigmatism and keratometric cylinder preoperatively and at 3, 6 and 12 months postoperatively were similar between the two groups.

CONCLUSIONS

FSL or trephine DALK are viable options for keratoconus, ectasia and corneal scars. Earlier visual recovery occurs with FSL mushroom configuration compared with MT straight-edge DALK.

Lamellar keratoplasty: a literature review

The concept of lamellar keratoplasty (LK) is not new. However, newer forms of lamellar keratoplasty techniques have emerged in the last decade or so revolving around the concept of targeted replacement of diseased corneal layers. These include anterior lamellar keratoplasty (ALK) techniques that aim to selectively replace diseased corneal stroma and endothelial keratoplasty techniques aiming to replaced damaged endothelium in endothelial disorders. Recent improvements in surgical instruments and introduction of new techniques as well as inherent advantages such as preservation of globe integrity and decreased graft rejection have resulted in the reintroduction of LK as an acceptable alternative to conventional PK. In this review, indications, benefits, limitations, and outcomes of various anterior and posterior lamellar keratoplasty techniques are discussed.

Comparison of descemet-on versus descemet-off deep anterior lamellar keratoplasty

PURPOSE

To determine the effect of retained donor Descemet membrane (DMs) on visual outcomes, contrast sensitivity (CS), higher-order aberrations (HOAs), and central graft thickness after deep anterior lamellar keratoplasty (DALK) using the big-bubble technique.

METHODS

In this retrospective comparative study, keratoconic eyes undergoing a DALK using the big-bubble technique were enrolled. A bared DM was achieved in all cases. A donor cornea without (group 1; 48 eyes) or with (group 2; 22 eyes) DM was sutured to the recipient bed. The 2 groups were compared in terms of best spectacle-corrected visual acuity, keratometric astigmatism, refractive error, CS, HOAs, and central graft thickness at least 3 months after complete suture removal. Additionally, the rate of postoperative pseudoanterior chamber formation was compared between the study groups.

RESULTS

The mean follow-up duration was 23.2 ± 6.9 months in group 1 and 26.5 ± 6.5 months in group 2 (P = 0.61). The postoperative best spectacle-corrected visual acuity was 0.18 ± 0.08 logMAR and 0.24 ± 0.30 logMAR, respectively (P = 0.36). The 2 groups had comparable postoperative keratometric astigmatism, spherical equivalent refraction, and HOAs. In terms of CS, however, group 1 demonstrated better results at a low spatial frequency. The mean postoperative central graft thickness was greater in group 2 (589.8 ± 34.5 μm) than in group 1 (523.6 ± 63.0 μm; P < 0.001). A pseudoanterior chamber developed in 3 eyes of group 1 and in 2 eyes of group 2 (P = 0.23). All cases were successfully managed by giving an intracameral air injection.

CONCLUSIONS

DALK performed using the big-bubble technique for keratoconus may give better results in terms of CS if a donor cornea without DM is transplanted.

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.

Clinical evaluation of Deep Anterior Lamellar Keratoplasty (DALK) for stromal corneal opacities

BACKGROUND

Corneal scars are commonly formed following many diseases of the eye like trauma, inflammation and infections. They lead to permanent diminution of vision which can be managed by Penetrating Keratoplasty (PK). PK is removing diseased as well as healthy tissues and is associated with many post-operative complications. Deep Anterior Lamellar Keratoplasty (DALK) is a relatively newer procedure which replaces only the diseased stroma, leaving the original corneal endothelium intact. This procedure is associated with lesser incidence of post-operative complications.

METHODS

The study was conducted at a large tertiary care centre. 10 patients with stromal corneal scars were subjected to DALK and results were analysed after 06 months. Poor quality donor corneal tissue of B- and C grade was used in all cases.

RESULTS

7 out of 10 patients (70%) undergoing DALK had post-operative visual acuity of 6/24 or better. 03 patients who did not have adequate recovery of visual acuity were due to over-riding of the graft in 01 case (10%), fungal keratitis in 01 case (10%) and interface haze in 01 case (10%).

CONCLUSION

DALK is a promising new technique for management of superficial corneal stromal scars using poor quality donor corneal tissue. Initial results are encouraging with minimal complications.

Corneal endothelium after deep anterior lamellar keratoplasty and penetrating keratoplasty for keratoconus: a four-year comparative study

PURPOSE

To compare the status of corneal endothelium and central corneal thickness within the first four postoperative years after deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) in patients with keratoconus.

MATERIALS AND METHODS

Thirty-nine eyes (Group A) which had PK and 44 eyes (Group B) which had DALK for the treatment of keratoconus were included in this retrospective study. The endothelial cell density (ECD), the mean endothelial cell area and the coefficient of variation of cell area were assessed with a non-contact specular microscope, and the central corneal thickness (CCT) was measured with an ultrasound pachymeter.

RESULTS

Mean ECD loss rate at two years was 36.24% in Group A and 18.12% in Group B (P<0.001). Mean ECD loss rate at four years was 47.82% in Group A and 21.62% in Group B (P<0.001). Mean annual ECD loss rate was calculated 14.12% per year in Group A and 5.78% per year in Group B. In the PK group, increase in mean CCT was 15.60% in two years and 15.03% in four years, while in the DALK group, mean CCT increased by 8.05% in two years and 9.31% in four years.

CONCLUSIONS

As the majority of ectatic disorders such as keratoconus occur in young people, long-term endothelial cell survival following treatment with keratoplasty is essential for the long-term visual ability. Our finding that corneal endothelial cell loss in the DALK group occurs at a slower rate than in the PK group suggests DALK as a safer alternative to PK in these selected patients.

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.

Long-term results of deep anterior lamellar versus penetrating keratoplasty

OBJECTIVE

To compare deep anterior lamellar keratoplasty (DALK) with penetrating keratoplasty (PK) in eyes with corneal diseases not involving the corneal endothelium (keratoconus, scars after infectious keratitis, stromal dystrophies, and trauma).

DESIGN

Retrospective, comparative case series.

PARTICIPANTS

One hundred forty-two consecutive DALK (DALK group; big-bubble technique or manual lamellar dissection using a slitlamp) and 142 matched PK (PK group).

METHODS

Three models were used to describe the postoperative outcomes of the endothelial cell density. A joint regression model was used to predict long-term graft survival. Visual acuity, ultrasound pachymetry, specular microscopy, and optical coherence tomography (OCT) findings were recorded.

MAIN OUTCOME MEASURES

Postoperative endothelial cell loss and long-term predicted graft survival.

RESULTS

The average 5-year postoperative endothelial cell loss was -22.3% in the DALK group and -50.1% in the PK group (P<0.0001). The early- and late-phase annual rates of endothelial cell loss were -8.3% and -3.9% per year, respectively, in the DALK group and -15.2% and -7.8% per year in the PK group (P<0.001; biphasic linear model). The median predicted graft survival was 49.0 years in the DALK group and 17.3 years in the PK group (P<0.0001). The average visual acuity was lower in the manual dissection subgroup compared with the PK group (average difference, 1.0 to 1.8 line) and with the big-bubble subgroup (average difference, 2.2 to 2.5 lines). The average central corneal thickness at 12 months was 536 μm in the PK group, 523 μm in the big-bubble subgroup, and 562 μm in the manual dissection subgroup (P<0.001). The average thickness of the residual recipient stroma measured by OCT was 87±26 μm in the manual dissection subgroup. No correlation was found between this figure and logarithm of the minimal angle of resolution at any postoperative time point (P>0.05).

CONCLUSIONS

Long-term, model-predicted graft survival and endothelial densities are higher after DALK than after PK. The big-bubble technique gives better results than manual dissection and PK. Compared with PK, manual dissection provides higher survival of both the corneal endothelium and graft, but lower visual acuity.

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.

Economic evaluation of deep anterior lamellar keratoplasty versus penetrating keratoplasty in The Netherlands

PURPOSE

To evaluate the cost effectiveness of deep anterior lamellar keratoplasty (DALK) versus penetrating keratoplasty (PK) in The Netherlands.

DESIGN

Cost-effectiveness analysis alongside a randomized, multicenter clinical trial.

METHODS

Fifty-three patients with corneal stromal pathologic features not affecting the endothelium were included with 28 patients in the DALK group and 25 in the PK group. Quality of life was measured before surgery and 3, 6, and 12 months after surgery. The main outcome measures were incremental cost-effectiveness ratios per clinically improved patient on the 25-item National Eye Institute Visual Functioning Questionnaire and per patient with endothelial cell loss of maximally 20% within the first year.

RESULTS

Mean total bootstrapped costs per patient were €7607 (US$10,498) in the DALK group and €6552 (US$9042) in the PK group. The incremental cost-effectiveness ratios were €9977 (US$13,768) per clinically improved patient on the 25-item National Eye Institute Visual Functioning Questionnaire and €6900 (US$9522) per patient with cell loss of maximally 20%. In patients without perforation of the Descemet membrane, the incremental cost-effectiveness ratio was €5250 (US$7245) per patient.

CONCLUSIONS

This study shows that DALK is more costly and more effective as compared with PK. Results on the 25-item National Eye Institute Visual Functioning Questionnaire were in favor of DALK, and endothelial cell loss in DALK patients remained stable after 6 months, whereas cell loss in PK patients continued. Furthermore, DALK procedures performed without perforation of the Descemet membrane were more effective. However, because it is unknown what society is willing to pay for an additional improved patient, cost effectiveness of DALK within a limited follow-up period of 12 months is unclear. Cost effectiveness of DALK may improve over time because of lower graft failure.

Deep anterior lamellar keratoplasty as an alternative to penetrating keratoplasty a report by the american academy of ophthalmology

OBJECTIVE

To review the published literature on deep anterior lamellar keratoplasty (DALK) to compare DALK with penetrating keratoplasty (PK) for the outcomes of best spectacle-corrected visual acuity (BSCVA), refractive error, immune graft rejection, and graft survival.

METHODS

Searches of the peer-reviewed literature were conducted in the PubMed and the Cochrane Library databases. The searches were limited to citations starting in 1997, and the most recent search was in May 2009. The searches yielded 1024 citations in English-language journals. The abstracts of these articles were reviewed, and 162 articles were selected for possible clinical relevance, of which 55 were determined to be relevant to the assessment objective.

RESULTS

Eleven DALK/PK comparative studies (level II and level III evidence) were identified that compared the results of DALK and PK procedures directly; they included 481 DALK eyes and 501 PK eyes. Of those studies reporting vision and refractive data, there was no significant difference in BSCVA between the 2 groups in 9 of the studies. There was no significant difference in spheroequivalent refraction in 6 of the studies, nor was there a significant difference in postoperative astigmatism in 9 of the studies, although the range of astigmatism was often large for both groups. Endothelial cell density (ECD) stabilized within 6 months after surgery in DALK eyes. Endothelial cell density values were higher in the DALK groups in all studies at study completion, and, in general, the ECD differences between DALK and PK groups were significant at all time points at 6 months or longer after surgery for all of the studies reporting data.

CONCLUSIONS

On the basis of level II evidence in 1 study and level III evidence in 10 studies, DALK is equivalent to PK for the outcome measure of BSCVA, particularly if the surgical technique yields minimal residual host stromal thickness. There is no advantage to DALK for refractive error outcomes. Although improved graft survival in DALK has yet to be demonstrated, postoperative data indicate that DALK is superior to PK for preservation of ECD. Endothelial immune graft rejection cannot occur after DALK, which may simplify long-term management of DALK eyes compared with PK eyes. As an extraocular procedure, DALK has important theoretic safety advantages, and it is a good option for visual rehabilitation of corneal disease in patients whose endothelium is not compromised.

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.

Predicted long-term outcome of corneal transplantation

OBJECTIVE

To analyze graft survival and the outcome of the corneal endothelium after corneal transplantation in a single model to predict the long-term prognosis of these grafts.

DESIGN

Cohort study. Data were recorded prospectively and then analyzed retrospectively.

PARTICIPANTS

One thousand one hundred forty-four consecutive eyes of 1144 patients who underwent corneal transplantation between 1992 and 2006.

INTERVENTIONS

Penetrating keratoplasty and deep anterior lamellar keratoplasty.

MAIN OUTCOME MEASURES

Slit-lamp examination and wide-field specular microscopy results. A joint analysis of endothelial cell loss and time to graft failure was undertaken. From midterm simultaneous analysis of graft survival and endothelial cell loss, long-term graft survival was predicted.

RESULTS

The observed 5- and 10-year graft survival estimates were, respectively, 74% and 64%. The average endothelial cell density (cell loss) was 2270 cells/mm(2) before surgery, 1058 cells/mm(2) (-53%) during the sixth postoperative year, and 865 cells/mm(2) (-61%) during the 10th postoperative year. Overall, the predicted graft survival estimate was 27% at 20 years and 2% at 30 years. Both observed and predicted graft survival were higher in patients who had undergone lamellar keratoplasty than in patients who had undergone penetrating keratoplasty and had normal recipient endothelium and higher in patients who had undergone penetrating keratoplasty and had normal recipient endothelium than in patients who had undergone penetrating keratoplasty and had impaired recipient endothelium.

CONCLUSIONS

For corneal diseases involving the endothelium, penetrating keratoplasty seems to be a good therapeutic approach in elderly patients because the graft life-span may be similar to the patient life expectancy. Conversely, for younger patients, penetrating keratoplasty is only a midterm therapeutic approach. For corneal diseases not involving the endothelium, deep anterior lamellar keratoplasty seems to be a promising therapeutic approach with higher long-term expected survival.