Deep anterior lamellar keratoplasty: A surgeon's guide

Using Artificial Intelligence for an Efficient Prediction of Outcomes of Deep Anterior Lamellar Keratoplasty (DALK) in Advanced Keratoconus

Purpose

To identify and analyze clinical risk factors and imaging parameters influencing the outcomes of deep anterior lamellar keratoplasty (DALK) for advanced keratoconus (KC) using an artificial intelligence (AI) model.

Methods

This study included 250 DALK eyes with a 5-year follow-up for advanced KC. The DALK eyes were classified as having "favorable" or "unfavorable" outcomes based on graft clarity, scarring at the graft-host interface involving the visual axis which was not pre-existing, early suture loosening less than 3 months after the surgery, corneal vascularization reaching up to or into the graft-host junction at any follow up period, persistent corneal edema greater than 3 months after surgery, and change in visual acuity. Clinical risk factors were determined through a detailed clinical evaluation and questionnaire assessment and included the presence of systemic allergy, ocular allergy, or eye rubbing. Immunoglobulin E (IgE) and vitamin D and B12 levels were obtained from blood investigations. A total of 37 tomographic parameters were exported from an OCULUS Pentacam HR. An AI model was then built to assess these risk factors and imaging parameters. The area under the curve (AUC) and other metrics were evaluated.

Results

The AI model classified 92.2% and 89.4% cases as favorable or unfavorable, respectively, based on clinical risk factors and imaging parameters. Systemic allergy, IgE, eye rubbing, and vitamin D had the highest information gains followed by posterior corneal data from the Pentacam HR. The AI model achieved an AUC of 0.957 with sensitivity of 98% and specificity of 85.6%.

Conclusions

Our findings demonstrate the importance of preoperative risk stratification, which can affect surgical outcomes of DALK using AI.

Translational Relevance

Better identification and control of these factors would enable better management and outcomes of DALK for advanced KC.

Outcomes of Corneal Collagen Crosslinking Under General Anesthesia in Down Syndrome

PURPOSE

Down syndrome is one of the strongest risk factors of keratoconus. Corneal collagen crosslinking (CXL) is the standard-of-care treatment to reduce progression, but there is limited published literature about CXL in patients with Down syndrome. We sought to describe outcomes of epithelium-off CXL under general anesthesia in patients with Down syndrome and keratoconus.

METHODS

We conducted a retrospective descriptive case series at a single tertiary pediatric hospital. Standard epithelium-off Dresden protocol CXL under general anesthesia was performed in all cases. Preoperative and postoperative corneal characteristics were obtained. All perioperative and postoperative complications were reported.

RESULTS

Between August 2020 and February 2024, CXL was performed on 34 eyes of 20 patients with Down syndrome. The mean age was 20.2 years at the time of crosslinking. The mean preoperative Kmax was 62.3 diopters (range 45.5-95.4), with a mean preoperative central corneal thickness of 466 μm (range 306-538). Visual acuity post procedure in patients seen 1 week postoperatively was stable to improved. One eye developed corneal edema that resolved within 3 weeks postoperatively, and another was found to have new apical scarring a year after the procedure. No other complications were noted.

CONCLUSIONS

Keratoconus was diagnosed at an advanced stage in most of the patients with Down syndrome in our cohort. Epithelium-off CXL under general anesthesia was well tolerated. Though follow-up was limited, our results suggest that CXL is feasible and effective in keratoconus associated with Down syndrome.

Bio-orthogonal crosslinking and hyaluronan facilitate transparent healing after treatment of deep corneal injuries with in situ-forming hydrogels

Corneal transplantation is the primary treatment for corneal blindness, affecting millions globally. However, challenges like donor scarcity and surgical complications remain. Recently, in situ-forming corneal stroma substitutes have emerged, offering potential solutions to these limitations. These substitutes enable liquid-to-hydrogel formation in situ, eliminating sutures and reducing complications. Here we performed a direct, side-by-side comparison of a composite hyaluronan-collagen (HA-Col) hydrogel crosslinked by either photochemistry or bio-orthogonal chemistry to ascertain the impact of reaction specificity on corneal wound healing. Testing in rodent and rabbit models suggests that composite HA-Col gels crosslinked by bio-orthogonal chemistry results in more rapid and optically favorable wound healing compared to the same composition crosslinked by photochemistry as well as bio-orthogonally crosslinked collagen alone. These findings underscore biochemical parameters that may be important to the success of crosslinked, in situ-forming hydrogels as an alternative to corneal transplantation, with the potential for expanded access to treatment and improved outcomes.

Intraoperative Optical Coherence Tomography (OCT)-Guided Femtosecond Laser-Assisted Descemet Membrane Endothelial Keratoplasty (iFAD)

We describe retrospectively the indications and outcomes of nine patients who present with varying degrees of deep posterior stromal scarring or endothelial failure following deep anterior lamellar keratoplasty (DALK). These patients underwent a surgical strategy coined Intraoperative Optical Coherence Tomography Guided Femtosecond Laser-Assisted Descemet Membrane Endothelial Keratoplasty (iFAD). This strategy can be used to address suboptimal visual outcomes following primary DALK. Patients undergoing iFAD first had femtosecond laser-assisted trephination of the underlying posterior lamella using the liquid keratoplasty system on the Femto LDV Z8 platform (Zeimer Ophthalmic Systems AG, Port, Switzerland). A Descemet Membrane Endothelial Keratoplasty (DMEK) graft was subsequently transplanted in place of the removed lamella. Out of nine cases, major indications for seven included post-infective, blepharokeratoconjunctivitis (BKC) and deep stromal scarring related to stromal dystrophy. The remaining two had endothelial failure following primary DALK. The main benefits of this surgical approach are (1) Utilization of integrated real-time iOCT on the femtosecond laser platform allows for precise calibration of a wide range of vertical posterior trephination depths (96-329 microns) from the endothelial surface. (2) Femtosecond laser trephination utilizing a non-applanation liquid interface preserves trephination geometries and maximises precision-based surgical outcomes. (3) iFAD is a viable and straightforward technique for surgeons addressing patients who might otherwise require complex surgery to address residual deep stromal scars post-DALK.

Strategic Management of Descemet's Membrane Perforation During DALK in Advanced Keratoconus

Objective

To report on the surgical treatment of advanced keratoconus (KC) with stromal scarring in a young male patient with asymmetric disease progression complicated by an intraoperative microperforation of Descemet's membrane (DM) during deep anterior lamellar keratoplasty (DALK).

Methods

The surgical approach consisted of manual descemetic DALK (dDALK), further complicated with DM microperforation. Anterior segment ocular coherence tomography (AS-OCT) was used intraoperatively to locate the site and size of the tear. The surgeon decided not to convert to penetrating keratoplasty (PK), despite stromal scarring, significant ectasia, and variable corneal thickness, but rather to continue the dissection of the stromal bed with maximum precaution.

Results

Postoperatively, visual results improved and reached the best corrected visual acuity of 20/20. Choosing a proper graft dimension and reaching anatomical separation up to the DM were the keys to obtaining such a positive refractive outcome.

Discussions

DALK, the most advanced treatment for KC, was chosen as the ideal option for this young patient due to its advantages over PK: reduced rejection risk, fewer complications, quicker steroid tapering, and faster recovery. However, its steep learning curve remains a challenge for surgeons.

Conclusions

Despite manual DALK being a more challenging and time-consuming procedure than PK, careful dissection of the stromal bed and diligent assessment of the affected DM can provide a better and safer outcome for selected patients. Even if initial postoperative visual results are impressive, the surgeon must pay attention to the patient's future check-ups to swiftly correct any possible complications.

Main issues in deep anterior lamellar keratoplasty: A systematic narrative review

Deep anterior lamellar keratoplasty (DALK) has emerged as a transformative approach in managing corneal pathologies, notably keratoconus (KC), providing a viable alternative to penetrating keratoplasty (PK). This systematic review explores the intricacies of DALK, comparing its preoperative, intraoperative, and postoperative considerations with PK. Extensive literature searches revealed a wealth of data regarding DALK's advantages and challenges, with an emphasis on graft survival, visual outcomes, and complications. In the preoperative phase, DALK showcases its versatility, catering to a wide spectrum of patients, including those with KC and ocular surface disorders. Intraoperatively, it offers innovative techniques to address emphysema, bubble formation, and Descemet's membrane perforation, all while maintaining a strong focus on patient-centered outcomes. Postoperatively, DALK's lower rejection rates and decreased complications underscore its potential superiority over PK, although unique challenges such as graft failure from nonimmunologic factors demand vigilant management. This comprehensive review not only serves as a valuable resource for ophthalmic surgeons but also sheds light on the evolving landscape of corneal transplantation, highlighting DALK's role as a transformative force in the field.

Large-diameter deep anterior lamellar keratoplasty: A narrative review

Deep anterior lamellar keratoplasty (DALK) involves the selective replacement of diseased corneal stroma while preserving healthy unaffected endothelium. While DALK has failed to gain widespread popularity, improved visual and refractive outcomes of large-diameter grafts, which patients directly perceive following suture removal, may represent a compelling reason to shift toward DALK. Since the unaffected host endothelium is retained, DALK offers the opportunity to use large-diameter grafts, which reliably achieves maximum visual potential without an increased risk of immune-mediated stromal rejection. In this narrative review, we evaluate the current evidence on large-diameter DALK including surgical technique and clinical outcomes.

Deep Anterior Lamellar Keratoplasty Over Penetrating Keratoplasty to Mitigate Positive Vitreous Pressure Complications

This report describes deep anterior lamellar keratoplasty over penetrating keratoplasty (DALK-over-PKP) as an alternative technique to mitigate complications related to positive vitreous pressure (PVP) during PKP. We accomplished this by repairing the punctured cornea and performing a modified DALK where a full-thickness donor graft is placed over the host Descemet membrane, which is then removed after partial suturing of the graft. This mitigates the driving force behind the PVP by maintaining a closed-anterior chamber.

Bubbling With Confidence: A Study of Numerous Deep Anterior Lamellar Keratoplasty Cases Using Anwar's Big Bubble Technique

PURPOSE

This study aims to assess the postoperative results, variability, and complications of a hundred deep anterior lamellar keratoplasty cases. Study design and duration: This is an observational study. The study was conducted at Pak International Medical College (PIMC) for a duration of four years (January 2019-January 2023).

METHODOLOGY

Our study collected information on a hundred cases of deep anterior lamellar keratoplasty (DALK) utilizing Anwar's big bubble technique, consisting of patients with keratoconus, superficial corneal scars, and macular dystrophy. Consenting patients had their pre and postoperative visual acuities and keratometry readings recorded. Overall success and complications were recorded and compared with the present literature.

RESULTS

Big bubble formation was achieved in 87% (n = 87) eyes and not achieved in 13% (n=13). There was a significant reduction in keratometry values after the procedures as well as improved vision in all patients, with 84% reporting significant improvement. Descemet membrane exposure was achieved in 91% (n=91). Complications included the failure of Anwar's big bubble formation in 13% (n=13) patients and the failure to expose Descemet's in nine patients (9%).

CONCLUSION

DALK using the big bubble technique is a safe and effective procedure in patients with corneal diseases who have a healthy Descemet membrane and endothelium.

Keratoconus Diagnosis and Treatment: Recent Advances and Future Directions

Keratoconus is a disorder characterized by progressive corneal thinning and steepening that may result in significant visual impairment secondary to high astigmatism, corneal scarring, or even corneal perforation. Early detection and screening of keratoconus are essential for effective management and treatment. Several screening methods, such as corneal topography and tomography, corneal biomechanics, and genetic testing, are being developed to detect keratoconus at an early stage. Once detected, prevention of progression is the mainstay of keratoconus management. Corneal collagen cross-linking is a minimally invasive treatment option that can slow or halt the progression of keratoconus. Additionally, recent studies have investigated the potential use of copper sulfate eye drops (IVMED-80) and extracellular vesicles to prevent the progression of keratoconus as non-invasive treatment options. For visual rehabilitation, currently available treatments include scleral lenses, intracorneal ring segments, corneal allogenic intrastromal ring segments, and deep anterior lamellar keratoplasty. The safety and efficacy of these emerging treatment options for keratoconus are currently being investigated.

Comparison of Robot-Assisted and Manual Cannula Insertion in Simulated Big-Bubble Deep Anterior Lamellar Keratoplasty

This study aimed to compare the efficacy of robot-assisted and manual cannula insertion in simulated big-bubble deep anterior lamellar keratoplasty (DALK). Novice surgeons with no prior experience in performing DALK were trained to perform the procedure using manual or robot-assisted techniques. The results showed that both methods could generate an airtight tunnel in the porcine cornea, and result in successful generation of a deep stromal demarcation plane representing sufficient depth reached for big-bubble generation in most cases. However, the combination of intraoperative OCT and robotic assistance received a significant increase in the depth of achieved detachment in non-perforated cases, comprising a mean of 89% as opposed to 85% of the cornea in manual trials. This research suggests that robot-assisted DALK may offer certain advantages over manual techniques, particularly when used in conjunction with intraoperative OCT.

Inadvertent Viscoelastic Separation of the Pre-Descemet (Dua) Layer in Deep Anterior Lamellar Keratoplasty With Structural Features Revealed by Polarization Microscopy

INTRODUCTION

Deep anterior lamellar keratoplasty (DALK) is a corneal transplant technique that removes the host stroma down to either the pre-Descemet (Dua) layer or Descemet membrane. It is most common for the big bubble technique to create a cleavage plane between the posterior stroma and the pre-Descemet layer. This is advantageous because the pre-Descemet layer has been found to be much stronger than Descemet membrane, and makes the procedure easier to perform. In this report, we present an uncommon viscoelastic-related complication of DALK that resulted in excising the pre-Descemet layer and allowing it to be studied using polarization microscopy.

METHODS

DALK was performed using a standard big bubble technique. Postoperatively, a double anterior chamber was found to have been created by the inadvertent passage of an ophthalmic viscoelastic device (OVD) through the pre-Descemet layer. This resulted in the OVD being trapped between the pre-Descemet layer and Descemet membrane. The pre-Descemet layer was then resected in a subsequent operation. The pre-Descemet layer and posterior stroma were studied by polarization microscopy using Sirius Red histochemical staining to elucidate the orientation of the collagen fibers.

RESULTS

The pre-Descemet layer is composed of lamellar arrays of collagen that have consistent polarization properties within each layer but show variable polarization of the strands, indicative of anisotropic strand orientation. The degree of variable polarization of the pre-Descemet layer is distinct from the overlying posterior stroma.

CONCLUSIONS

Injecting an OVD into a big bubble in DALK may result in it being trapped between the pre-Descemet layer and Descemet membrane. The pre-Descemet layer shows alternating layers of varying polarization of collagen. This anisotropic structure helps explain the basis for the additional strength that the pre-Descemet layer is known to have.

Deep Anterior Lamellar Keratoplasty: Can All Ruptures Be Fixed?

PURPOSE

The aim of this study was to report our experience in managing different types of Descemet membrane (DM) ruptures during deep anterior lamellar keratoplasty (DALK).

METHODS

This study was a retrospective, consecutive, interventional case series of 1573 DALK procedures conducted on 1244 patients, performed between 2002 and 2017. Inclusion criteria consisted of a minimum of 24-month follow-up. DM rupture incidence, location, and surgical approach for repair were recorded. Postoperative measures were investigated only in eyes that experienced DM ruptures and included best spectacle-corrected visual acuity, endothelial cell loss, double anterior chamber, pupillary block, need for rebubbling, graft clarity, and rejection episodes.

RESULTS

One thousand four hundred forty-three eyes met the inclusion criteria. DM ruptures occurred in 119 eyes (8.25%). Seventy-eight percent of DM ruptures were microruptures (≤2 mm), and they occurred more frequently during manual DALK cases. Macroruptures were less frequent (22%), and they occurred more frequently during subtotal and total anterior lamellar keratoplasty (STALK-TALK) cases. In general, DM ruptures mainly occurred in the peripheral cornea (95% of cases). One hundred (84%) of the 119 ruptures resolved by the first postoperative day. Nineteen cases (16%) developed double anterior chamber; all resolved by using different strategies. No intraoperative penetrating keratoplasty conversion was recorded. Pupillary block occurred in 7 cases (5.9%), but no Urrets-Zavalia syndrome was observed. The average postoperative endothelial cell loss was 410 ± 39 cells/mm 2 (19%) at 1-year follow-up, and there was no significant difference between cases requiring a rebubbling and cases that did not ( P = 0.896). All grafts but one were clear at the last follow-up. Graft failure from endothelial decompensation occurred in this lone case (0.8%).

CONCLUSIONS

It is worth trying to repair all DM ruptures in DALK, and immediate penetrating keratoplasty conversion should be avoided. Understanding the physiomechanical mechanisms in DALK allows to correctly choose a proper rescue strategy to successfully repair DM ruptures.

Current approaches in the management of patients with keratoconus

Keratoconus is a relatively frequent eye disease, especially in young patients, in which the cornea gradually thins and deforms in a cone shape. In the past, it could be treated only with glasses, rigid contact lenses or, for advanced cases, penetrating corneal transplant. Nowadays, corneal cross-linking, intracorneal ring segments implantation or deep anterior lamellar keratoplasty are available options of treatment, along with the above mentioned ones. Several studies focused on this disease and its management attempted to establish the applicability of these treatment methods in current practice. In the early stages, glasses or soft toric contact lenses are able to correct the astigmatism, but, as the disease progresses, rigid contact lenses are indicated. Corneal cross-linking is done in order to slow down or even stop the progression of the disease. Implanting intracorneal ring segments helps improve visual acuity in patients with low vision that cannot be corrected otherwise. Advanced stages need corneal transplant, either penetrating or anterior lamellar, depending on each patient's ocular characteristics. Thus, keratoconus treatment is individualized for every patient, according to the stage of the disease. Moreover, because of the new developed technology, keratoconus patients can benefit from efficient treatment, in much safer conditions.

Clear Cornea Femto DALK: a novel technique for performing deep anterior lamellar keratoplasty

PURPOSE

A new femtosecond laser assisted deep anterior lamellar keratoplasty technique (Clear Cornea Femto DALK or CCF DALK) can be performed with less technical challenges compared to conventional procedures. This paper reports on a preliminary case series to evaluate the technique.

METHOD

First, through a clear cornea approach, Descemet's membrane (DM) is completely separated from posterior stroma by injection of balanced salt solution/viscoelastic substance through a special cannula inserted into the deep stroma and positioned right above the DM without perforating. The injection creates a liquid chamber that detaches the DM while preserving a reasonably transparent corneal stroma. Afterwards, a complete posterior/anterior trephination of the stroma, from the liquid chamber to the epithelium, is done using a femtosecond laser system under optical coherence tomography control.

RESULTS

This technique was successfully performed in a preliminary series of 10 eyes/10 patients. All patients had the DM completely bared and kept their own endothelial cell population with minimal cell loss (< 15%) after 6 months. Postoperative interface reaction was minimal, and no immune reactions were observed thus far.

CONCLUSION

Clear Cornea Femto DALK is a promising alternative to previous Femto DALK procedures with good acceptance of the tissue seen to date.

The Effects of Donor-Recipient Age and Sex Compatibility in the Outcomes of Deep Anterior Lamellar Keratoplasties

Purpose

Corneal transplantations are the commonest allogenic transplant surgeries performed worldwide. Transplantable grade donor cornea is a finite resource. There is thus an impetus for eye banks to optimize the use of each harvested cornea, and clinicians to minimize the risks of graft rejection and failure. With better survival and lower rejection rates, anterior lamellar keratoplasty has gained popularity as an alternative technique to full-thickness penetrating keratoplasty, for the treatment of corneal stromal diseases. This study evaluated the effects of donor-recipient age- and sex-matching on the outcomes of eyes that had undergone deep anterior lamellar keratoplasty (DALK) surgeries.

Design

Observational cross-sectional study (national corneal graft registry data).

Subjects

All DALK surgeries performed in a tertiary ophthalmic hospital over an 11-year period.

Methods

To analyse the effects of donor-recipient sex-matching, transplantations were classified as “presumed H-Y incompatible” (male donor to female recipient) or “presumed H-Y compatible” (all other donor-recipient sex combinations). For age-matching, differences in donor and recipient ages were calculated. Cox proportional hazards regressions were used to evaluate the influence of donor-recipient sex-matching and age-matching on graft failure and rejection.

Main Outcome Measures

Rates of graft failure and rejection within each group.

Results

401 eyes were included. 271 (67.6%) transplants were presumed H-Y compatible. 29 (7.2%) grafts failed and 9 (2.2%) grafts rejected. There were trends of lower hazard ratios (HRs) in graft failure and rejection in the presumed H-Y compatible group [HRs: 0.59 (95% CI 0.20–1.77, p = 0.34) and 0.93 (95% CI 0.22–3.89, p = 0.926), respectively]. Median difference in age between recipients and donors was 15.0 years (IQR −2.8–34.3). The HRs of graft failure and rejection were not influenced by donor-recipient age [HRs per 1-year increase in age difference: 0.995 (95% CI 0.98–1.01, p = 0.483) and 1.01 (95% CI 0.99–1.03, p = 0.394), respectively].

Conclusion

In eyes that had undergone DALK surgeries, no significant influence of donor-recipient sex- or age-matching on graft rejection and failure was observed. Without strong evidence and the limitations of obtaining sample sizes required for an adequately powered study, the benefits of sex- and age-matching of donors and recipients during graft allocation for DALK surgeries is currently inconclusive.

Relationship between Postoperative Intraocular Pressure and Refractive Outcomes in Patients after Deep Anterior Lamellar Keratoplasty

Purpose

To study the effect of intraocular pressure (IOP) on refractive outcomes after deep anterior lamellar keratoplasty (DALK).

Methods

This retrospective study included eyes which underwent DALK. DALK technique involved either modified Anwar big-bubble if possible or manual anterior lamellar dissection. Our main outcome measures are postoperative IOP and refractive outcomes at postoperative week and months 1, 3, 6, and 12.

Results

Fifty-nine eyes of 59 patients were included. DALK was performed for optical (93.2%) and tectonic (6.8%) purposes. 76.3% of the patients had keratoconus. Anwar's big-bubble technique was successful in 30 cases. Linear mixed-model was used to analyze the effect of the highest postoperative IOP measured prior to measurement of postoperative cylinder. Patients with greater maximum postoperative IOP measured had worse postoperative cylinder (P = 0.015) and spherical equivalent (P = 0.012). Those with IOP more than 21 mmHg had worse postoperative cylinder (P = 0.050) and spherical equivalent (P = 0.054). The method of DALK and presence of suture removal were not shown to statistically affect postoperative cylinder.

Conclusion

Our study shows a positive correlation between postoperative IOP and worse spherical equivalent and cylinder post-DALK, emphasizing the need for good IOP control with IOP-lowering medication(s).

Corneal Perforation as a Complication of Fungal Interface Infectious Keratitis after Deep Anterior Lamellar Keratoplasty

Deep anterior lamellar keratoplasty (DALK) is a surgical intervention for corneal diseases that do not affect the endothelium. The creation of an interface between the donor graft and recipient bed is a typical feature of DALK. Interface infectious keratitis (IIK) is an uncommon complication that originates at this point of contact. The onset of IIK following lamellar keratoplasty can cause delayed visual loss and subsequent endophthalmitis, with primarily fungal etiology (e.g., Candida spp.) and occasionally bacterial etiology. Infection of the lamellar interface may be attributed to contamination of the donor material or to precipitating factors such as loose sutures, persistent epithelial defects, and prolonged topical steroid use; fungal IIK is frequently resistant to medical treatment. Here, we describe the previously unreported occurrence of corneal perforation as a complication of fungal IIK after DALK. A 26-year-old otherwise healthy woman underwent uneventful DALK for advanced keratoconus in the left eye. She was discharged with instructions to apply topical prednisolone acetate and topical moxifloxacin. Culture of the donor corneoscleral rim showed growth of Candida glabrata, although the patient exhibited no clinical signs of infection. Approximately 3 months later, the patient exhibited mild blurring of vision in her left eye. Therefore, treatment was modified to topical amphotericin B and oral voriconazole. One week later, the patient developed multiple, sheath-like whitish creamy infiltrates, primarily in the lamellar interface; a positive Seidel test result indicated the presence of corneal perforation. As treatment for IIK, excisional penetrating keratoplasty (PK) was performed, followed by topical amphotericin B and topical prednisolone acetate treatment. During 12 months of follow-up after PK, the corneal graft was clear and there was no clinical evidence of recurrent keratitis. Prompt excisional PK prevented the progression of IIK to endophthalmitis in our patient. Early intervention with excisional PK should be considered when a diagnosis of fungal IIK is suspected in a patient with a positive donor rim culture, and in whom the condition does not respond to medical treatment. This early intervention is essential to prevent delayed treatment, which could result in corneal perforation and endophthalmitis, with ultimately poor visual outcomes.

Modified big-bubble for deep anterior lamellar keratoplasty

A new technique of air injection is described for big-bubble deep anterior lamellar keratoplasty (DALK) in eyes with keratoconus, along with a comparative analysis of the original technique. Fifty eyes were analyzed in each group. The mean steep keratometry and anterior chamber depth distribution were comparable between the 2 groups. The mean size of type 1 bubble achieved with single air injection (Group 1) was 7.8 ± 0.4 mm (range 6.5 to 8.5 mm), and with sequential air injection (Group 2) was 8.5 ± 0.3 (range 8 to 9 mm) (P < .001). Intraoperative complications of spontaneous bursting of bubble in 1 eye (2%) and peripheral microperforation in 3 eyes (6%) occurred only in Group 1. The modified technique of big-bubble DALK using sequential air injection aided by paracentesis to lower intraocular pressure allowed enlargement of a type 1 bubble in a safe and controlled manner with minimal risk for complications.

Tectonic Deep Anterior Lamellar Keratoplasty to Treat Corneal Perforation and Descemetocele from Microbial Keratitis

Purpose

To evaluate the result of tectonic deep anterior lamellar keratoplasty (DALK) for keratitis with perforation and descemetocele.

Patients and Methods

A prospective clinical study of 36 patients (36 eyes) treated with tectonic DALK for corneal perforation or descemetocele from microbial keratitis managed at the Vietnam National Eye Hospital over a two-year period. The surgical technique was manual lamellar dissection. The grafts were harvested from the anterior corneal cap of pre-cut donor tissues used for DSAEK or donor corneas with a low endothelial cell count.

Results

A mean age was 55.36 ± 13.98 years (ranged from 25 to 75 years). Female gender represented 52%. causative agents were herpes simplex virus (58.3%), bacteria (22.2%), fungi (13.9%) and microsporidia (5.6%). There were 24 eyes with descemetocele (66.7%) and 12 with perforation (33.3%). There were 33 successful cases (91.7%) and 3 failed cases (8.3%). Best corrected visual acuity (BCVA) improved in 28 eyes (84.8%). The range of post-operative BCVA was from hand motions to 20/70. Eleven eyes (33.3%) attained vision 20/200 and higher. Clear graft was obtained in 15 eyes (45.5%), while mild or severe graft opacity was observed in 14 eyes (42.4%), and 4 eyes (12.1%), respectively. Surgical complications included descemet rupture (20.8%), pseudo anterior chamber (41.6%), persistent corneal epithelial defects (8.3%), reinfection (11.1%), glaucoma or ocular hypertension (5.6%) and cataract (8.3%).

Conclusion

The study demonstrates that DALK is an effective procedure to treat corneal descemetocele, especially when an urgent penetrating keratoplasty (PKP) cannot be performed.

Management of Corneal Clouding in Patients with Mucopolysaccharidosis

Mucopolysaccharidoses (MPS) are a rare group of lysosomal storage disorders characterized by the accumulation of incompletely degraded glycosaminoglycans (GAGs) in multiple organ systems including the eye. Visual loss occurs in MPS predominantly due to corneal clouding and retinopathy, but the sclera, trabecular meshwork and optic nerve may all be affected. Despite the success of therapies such as enzyme replacement therapy (ERT) and hematopoietic stem-cell transplantation (HSCT) in improving many of the systemic manifestations of MPS, their effect on corneal clouding is minimal. The only current definitive treatment for corneal clouding is corneal transplantation, usually in the form of a penetrating keratoplasty or a deep anterior lamellar keratoplasty. This article aims to provide an overview of corneal clouding, its current clinical and surgical management, and significant research progress.

Preferred practice pattern and observed outcome of deep anterior lamellar keratoplasty - A survey of Indian corneal surgeons

Purpose

This study aimed to assess the preferred surgical technique and outcome of deep anterior lamellar keratoplasty (DALK) among corneal surgeons in India.

Methods

An online questionnaire-based cross-sectional survey was conducted among members of the Cornea Society of India (CSI) with experience of performing >10 DALK procedure. The responses pertaining to their surgical experience, preferred technique, complications, and outcome of DALK were collected and analyzed.

Results

A total of 156 responses were received. In total, 35.9% of participants reported annual keratoplasty of >50, and DALK constituted >25% surgeries for 25% of participants. Ectatic corneal disorder was reported as the most common indication for DALK by 71.6% of the respondents. Big-bubble (BB) DALK (WA-1.82) was the most preferred technique, along with suction trephine (50%) for partial trephination and bottom port cannula (45.5%) for BB formation. On statistical analysis, no difference was observed in the surgeon reported success rate of BB formation with or without anterior lamellar keratectomy (ALK) (χ2 (1,156) = 3.1498, P = 0.08) or paracentesis (χ2 (1,156) = 0.2737, P = 0.60) before stromal air injection, and method of stromal air injection (χ2 (1,156) = 4.7325, P = 0.09). Conversion to penetrating keratoplasty was reported by 16% of participants in >25% cases, while 66.7% reported in <10% cases. Cataract and double anterior chamber were the most common complications. 50% of participants suggested that >20 procedures are required to overcome the learning curve.

Conclusion

BB DALK is the most commonly practiced DALK technique, and its success is independent of ALK and paracentesis being performed prior to air injection and method of air injection (cannula/needle).

Evaluation of Clinical and Histological Outcomes of Adipose-Derived Mesenchymal Stem Cells in a Rabbit Corneal Alkali Burn Model

To assess effects of adipose-derived mesenchymal stem cells (AMSCs) in corneal alkali injuries in an experimental animal model. Twenty white New Zealand rabbits were included in the study. The animal models were randomly divided into 2 groups. Rabbits in the AMSC group (n = 10) received an intrastromal, a subconjunctival injection, and topical instillation of 0.5 ml totally of phosphate-buffered saline (PBS) containing 2 × 10⁶ AMSCs. In the control group (n = 10), rabbits received only 0.5 ml of PBS using the same methods. A masked investigator measured the corneal sensation, anterior chamber Inflammation (ACI), and conjunctival congestion. Additionally, a blind histological and immunohistochemical evaluation was made. In the AMSC group, the central corneal sensation was increased whereas ACI and conjunctival congestion were reduced compared to the control group in the 28 days of follow-up (p < 0.05). A statistically significant difference (p < 0.05) was noted between the two groups as recorded in the above parameters. Histological analysis showed that pathological vascularization was markedly reduced in the AMSC group which was consistent with the absence of factor VIII in the immunohistochemistry sections. There is a trend towards improved clinical outcomes including corneal sensation as well as acceleration in the restoration of normal corneal architecture in corneal alkali burns treated with AMSCs, results that support the need for further research in the field.

Surgeon Preference for Keratoplasty Techniques and Barriers to Performing Deep Anterior Lamellar Keratoplasty

PURPOSE

To identify barriers and facilitators to adopting deep anterior lamellar keratoplasty (DALK) for nonendothelial corneal pathology.

METHODS

An anonymous survey consisting of 22 multiple choice and free text questions was designed to gather information on demographic factors of surgeons and DALK surgical practices. The survey was emailed to members of the kera-net, a global online corneal surgeon/surgery platform.

RESULTS

A total of 100 surgeons completed the survey, most of whom practice in the United States (73%). Most surgeons (89%) reported performing DALK. Surgeons who did not learn DALK during fellowship (34%) tended to be in practice for higher numbers of years (P < 0.001). Surgeons in private practice are more likely to perform DALK versus those in other settings (92.7% vs. 80.8%, P = 0.087). Surgeons performing more corneal surgeries (at least 100 per year) are more likely to perform DALK than those who perform fewer than 100 per year (52% vs. 14%, P = 0.01). Surgeons who perform Descemet membrane endothelial keratoplasty are more likely to perform DALK than those who do not (81.7% vs. 18.3%, P = 0.014). There was also a positive correlation between PK and DALK surgical volumes (Spearman rank correlation coefficient = 0.57, P < 0.001). The main reasons for surgeon preference for DALK over PK were a desire to preserve the endothelium, intraoperative safety, and decreased complications. Longer surgical time and low patient volume were cited as barriers to adoption of DALK.

CONCLUSIONS

Alterations in DALK technique that reduce surgical time and providing more learning opportunities for DALK might improve adoption.

Re-Endothelialization of Bare Stroma after Descemet's Detachment due to Macroperforation during Deep Anterior Lamellar Keratoplasty

Purpose

To report a case with spontaneous re-endothelialization of bare stroma after subtotal detachment of Descemet's membrane (DM) due to macroperforation during deep anterior lamellar keratoplasty (DALK).

Methods

Case report.

Results

A 64-year-old patient underwent DALK for deep stromal scarring secondary to herpetic keratitis. During manual dissection, DM macroperforation occurred, and this was successfully managed intraoperatively and postoperatively. The DM with host posterior stroma remained attached for 10 months when it detached from the bare donor stroma. The cornea remained clear, with uncorrected distance visual acuity (UCVA) of 0.17 logMAR. After graft suture removal 30 months later, he was noted to have regular astigmatism and cataract for which he underwent phacoemulsification with toric intraocular lens implantation. Twenty-four months following his cataract surgery and 58 months following his DALK, his UCVA remains 0.17 logMAR and the cornea remains clear with no evidence of edema. His average specular count at 58 months was 1296 cell/mm² .

Conclusion

This case shows a very good visual outcome with clear cornea at 58 months despite of large DM detachment which happened 10 months following manual DALK with intraoperative macroperforation.

Amyloidosis and Ocular Involvement: an Overview

Purpose: To describe the ophthalmic manifestations of amyloidosis and the corresponding therapeutic measures.Methods: The 178 patients included in the study had different types of amyloidosis, diagnosed at a single internal medicine institution (Bari, Italy). To provide a comprehensive review of the types of amyloidosis that can be associated with ocular involvement, the images and clinical descriptions of patients with amyloidosis structurally related to gelsolin, keratoepithelin and lactoferrin were obtained in collaborations with the ophthalmology departments of hospitals in Mainz (Germany) and Helsinki (Finland).Results: Overall, ocular morbidity was detected in 41 of the 178 patients with amyloidosis (23%). AL amyloidosis was diagnosed in 18 patients with systemic disease, 3 with multiple myeloma, and 11 with localized amyloidosis. AA amyloidosis was detected in 2 patients with rheumatoid arthritis and 3 with Behçet syndrome, and transthyretin amyloidosis in 4 patients. The treatment of AL amyloidosis is based on chemotherapy to suppress the production of amyloidogenic L-chains and on surgical excision of orbital or conjunctival masses. AA amyloidosis is managed by targeting the underlying condition. Vitreous opacities and additional findings of ocular involvement in patients with transthyretin amyloidosis indicate the need for pars plana vitrectomy. Gelsolin amyloidosis, characterized by lattice corneal amyloidosis and polyneuropathy, results in recurrent keratitis and corneal scarring, such that keratoplasty is inevitable. In patients with lattice corneal dystrophies associated with amyloid deposits of keratoepithelin fragments, corneal transparency is compromised by deposits of congophilic material in the subepithelial layer and deep corneal stroma. Patients with established corneal opacities are treated by corneal transplantation, but the prognosis is poor because recurrent corneal deposits are possible after surgery. In patients with gelatinous drop-like dystrophy, the amyloid fibrils that accumulate beneath the corneal epithelium consist of lactoferrin and can severely impair visual acuity. Keratoplasty and its variants are performed for visual rehabilitation.Conclusion: A routine ophthalmic follow-up is recommended for all patients with established or suspected amyloidosis, independent of the biochemical type of the amyloid. Close collaboration between the ophthalmologist and the internist will facilitate a more precise diagnosis of ocular involvement in amyloidosis and allow the multidisciplinary management of these patients.Abbreviations: CD: corneal dystrophy; CLA: corneal lattice amyloidosis; CNS: central nervous system; CT: computed tomography; FAP: familial amyloidotic polyneuropathy; GDLCD: gelatinous drop-like corneal dystrophy; GLN: gelsolin; LCD: lattice corneal dystrophy; MRI: magnetic resonance imaging; OLT: orthotopic liver transplantation; TEM: transmission electron microscopy; TGFBI: transforming growth factor β induced; TTR: transthyretin.

Femtosecond laser-assisted deep anterior lamellar keratoplasty

PURPOSE OF REVIEW

A survey of the recent literature of deep anterior lamellar keratoplasty using femtosecond laser technology.

RECENT FINDINGS

There are several recent reports in the literature assessing technique and outcomes of deep anterior lamellar keratoplasty done with a femtosecond laser trephination. Most of these reports are laboratory studies and small case series with short-term outcomes. The laser technology is expensive and may not produce better results than conventional manual techniques. However, there are several theoretical advantages to femtosecond laser incisions in deep anterior lamellar keratoplasty that should be explored, including possible increased success of Descemet's membrane separation from stroma during surgery as well as postsurgical astigmatism benefits, earlier suture removal, and increased wound strength and healing.

SUMMARY

Femtosecond laser trephination in the setting of DALK may improve the technique by decreasing the number of descemet's membrane ruptures and improving short-term and long-term outcomes as compared with manual techniques. However, there is no consensus on a standardized approach for wound design or postoperative management. The literature would benefit from a prospective randomized controlled trial.