Deep Anterior Lamellar Keratoplasty Versus Penetrating Keratoplasty: A Meta-Analysis of Randomized Controlled Trials

Excimer Laser-Assisted Deep Anterior Lamellar Keratoplasty Versus Penetrating Keratoplasty for Patients With Keratoconus: A Retrospective Analysis From the Homburg Keratoconus Center

PURPOSE

To evaluate the outcome of excimer laser-assisted deep anterior lamellar keratoplasty (Exc-DALK) and penetrating keratoplasty (Exc-PKP) for keratoconus (KC).

METHODS

We included 123 eyes and compared the outcome of 30 eyes undergoing big-bubble Exc-DALK after stromal debulking (G1) against a matched group of 83 eyes undergoing Exc-PKP ( G2 ) in our department. G2 was created after performing a pseudorandom stratified bootstrapping of our PKP database starting with 2802 surgeries with removal of any bias. Main outcomes included best corrected visual acuity (BCVA), spherical equivalent (SE), tomographic changes, and endothelial cell density (ECD). Data were compared preoperatively, postoperatively with 2 double-running cross-stitch sutures according to Hoffmann [2 and 10 months postoperatively ( T1 and T2 )], after first suture removal [15 months postoperatively ( T3 )], and after final suture removal [26 months postoperatively ( T4 )].

RESULTS

Preoperatively, all parameters were comparable without significant differences. At T1, G1 showed significantly better BCVA ( P = 0.01), lower SE ( P = 0.04), lower anterior and posterior topographic astigmatism (ATA and PTA, P < 0.01), lower maximal keratometry ( P = 0.02), and lower central corneal thickness ( P < 0.01). At T2, G1 showed significantly better BCVA ( P = 0.04), lower PTA ( P < 0.01), and higher ECD ( P < 0.01). At T3, G1 showed significantly lower ATA ( P = 0.01) and PTA ( P < 0.01) and higher ECD ( P = 0.02). At T4, G1 showed significantly lower PTA and higher ECD ( P < 0.01) but no significant difference in BCVA ( P = 0.07).

CONCLUSIONS

Exc-DALK provided faster visual rehabilitation and represented an endothelial cell-sparing method compared with Exc-PKP. After final suture removal, Exc-DALK showed noninferior outcomes compared with Exc-PKP if the graft was placed on naked Descemet membrane.

Surgical Strategies to Manage Stromal Interface Irregularity Following Deep Anterior Lamellar Keratoplasty

PURPOSE

The purpose of this study was to describe the various surgical approaches to manage stromal interface irregularity following deep anterior lamellar keratoplasty (DALK).

METHODS

This interventional case series included patients requiring repeat keratoplasty procedures for stromal interface opacity and/or irregularity following DALK. The following surgical techniques with the aim of restoring transparency and regularity of the central optical zone and improving visual acuity in eyes that underwent unsuccessful DALK were performed: 1) simple anterior lamellar graft exchange, 2) repeat DALK with pneumatic dissection, 3) repeat DALK with deepening of manual lamellar dissection, 4) small diameter stripping of the central stroma-endothelium-Descemet complex and its replacement with a new endothelial lamella, and 5) 2-piece microkeratome-assisted mushroom penetrating keratoplasty. Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), slit-lamp examination, tonometry, and anterior corneal tomography were evaluated preoperatively, as well as 3, 6, and 12 months after surgery. Intraoperative and postoperative complications were recorded.

RESULTS

Preoperative BCVA was less than 20/200 and improved to 20/40 or better in all cases, reaching 20/20 in 1 patient. Corneal clarity was restored in all eyes, and no recurrence of underlying disease was observed. No intraoperative or postoperative complications were reported.

CONCLUSIONS

This case series describes several successful surgical approaches to improve the transparency and regularity of stromal interface obtained after a DALK procedure; the choice of the technique should be customized for the single eyes to still maintain the advantages of lamellar or minimally invasive grafts.

Interpretable Machine Learning-Based Risk Score for Predicting 10-Year Corneal Graft Survival After Penetrating Keratoplasty and Deep Anterior Lamellar Keratoplasty in Asian Eyes

PURPOSE

To predict 10-year graft survival after deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) using a machine learning (ML)-based interpretable risk score.

METHODS

Singapore Corneal Transplant Registry patients (n = 1687) who underwent DALK (n = 524) or PK (n = 1163) for optical indications (excluding endothelial diseases) were followed up for 10 years. Variable importance scores from random survival forests were used to identify variables associated with graft survival. Parsimonious analysis using nested Cox models selected the top factors. An ML-based clinical score generator (AutoScore) converted identified variables into an interpretable risk score. Predictive performance was evaluated using Kaplan-Meier (KM) curves and time-integrated AUC (iAUC) on an independent testing set.

RESULTS

Mean recipient age was 51.8 years, 54.1% were male, and majority were Chinese (60.0%). Surgical indications included corneal scar (46.5%), keratoconus (18.3%), and regraft (16.2%). Five-year and ten-year KM survival was 93.4% and 92.3% for DALK, compared with 67.6% and 56.6% for PK (log-rank P < 0.001). Five factors were identified by ML algorithm as predictors of 10-year graft survival: recipient sex, preoperative visual acuity, choice of procedure, surgical indication, and active inflammation. AutoScore stratified participants into low-risk and high-risk groups-with KM survival of 73.6% and 39.0%, respectively (log-rank P < 0.001). ML analysis outperformed traditional Cox regression in predicting graft survival beyond 5 years (iAUC 0.75 vs. 0.69).

CONCLUSIONS

A combination of ML and traditional techniques identified factors associated with graft failure to derive a clinically interpretable risk score to stratify PK and DALK patients-a technique that may be replicated in other corneal transplant programs.

Postoperative Astigmatism after Keratoplasty: A Systematic Review Meta-Analysis Based on PRISMA

Background: The number of corneal transplants is rising, with the aim to treat a spectrum of diseases ranging from dystrophies to corneal opacities caused by trauma or chemical burns. Refractive outcomes after this procedure are often impossible to predict and associated with high levels of astigmatism. However, there are many techniques that affect the reduction of astigmatism and improve the quality of life of patients. Objectives: The aim was to compare the improvement in postoperative visual acuity (logMAR) and amount of corneal astigmatism (Diopters) after corneal keratoplasty in patients who additionally underwent a surgical procedure, which affects the reduction in postoperative astigmatism, and to determine the most effective method. Search Methods and Selection Criteria: A thorough search was carried out across online electronic databases including PubMed, Embrase, Ovid MEDLINE, Scopus, and Web of Science, using combinations containing the following phrases: postoperative astigmatism, post-keratoplasty astigmatism, anterior lamellar keratoplasty (ALK), deep anterior lamellar keratoplasty (DALK), posterior lamellar keratoplasty, endothelial keratoplasty (EK), penetrating keratoplasty (PK), corneal transplant, keratoplasty, refractive surgery, kerato-refractive surgery, laser in situ keratomileusis (LASIK), and femtosecond LASIK. This was to determine all English-language publications that discuss refractive operations for postoperative or post-keratoplasty astigmatism. These bibliographies were searched for English-language publications published between 2010 and 2023. We proceeded to review each detected record's reference list. Data Extraction: Study characteristics such as study design, sample size, participant information, operations performed, and clinical outcomes were all extracted. Data Statistical Analyses: The Comprehensive Meta-Analysis software (version 3.3.070, 2014) was used to perform the analysis. The threshold of 0.05 for p-values was considered statistically significant. All effect sizes are reported as standardized differences (Std diff) in means with a 95% confidence interval (CI) and visualized graphically as forest plots. Publication bias is presented as a funnel plot of standard error by Std diff in means. Four methods were used to evaluate the heterogeneity among the studies: Q-value, I2, chi-square (χ2), and tau-squared. Main Results: We included 21 studies that randomized 1539 eyes that underwent corneal transplantation surgery either by PKP, DALK, or DSEAK techniques. The results showed the most significant improvement in the visual acuity and significant decrease in the corneal astigmatism after laser surgery procedures, like femtosecond-assisted keratotomy after DALK and PKP and LASIK after DSEAK.

Outcomes of large-diameter deep anterior lamellar keratoplasty and converted two-piece mushroom penetrating keratoplasty for herpetic corneal scars

PURPOSE

To report the clinical outcomes of large diameter deep anterior lamellar keratoplasty (DALK) and converted two-piece microkeratome-assisted mushroom keratoplasty (MK) for herpetic corneal scars.

METHODS

In this single-centre study, large diameter (9 mm) DALK was attempted in consecutive patients with herpetic corneal scars. In case of macroperforation or unsatisfactory clearance of the optical zone, the procedure was intraoperatively converted to two-piece microkeratome-assisted MK. Outcome measures were best spectacle-corrected visual acuity (BSCVA), refractive astigmatism, endothelial cell density (ECD), immunologic rejection, herpetic recurrence and graft failure rates in the two groups.

RESULTS

DALK was successfully performed in 98 of 120 eyes, while the remaining 22 eyes required intraoperative conversion to MK. At 5 years, mean logMAR BSCVA was 0.10 ± 0.12 in the DALK group and 0.09 ± 0.15 in the MK group (P = 0.75). Refractive astigmatism at 5 years was 2.8 ± 1.4 D in the DALK group and 3.0 ± 1.7 D in the MK group (P = 0.67). ECD was higher in the DALK group than in the MK group at all time points (P < 0.001), with a mean annual cell loss of 10.9% after MK and 4.2% after DALK. The 5-year risk for immunologic rejection (DALK: 3%, MK: 5%, P = 0.38), herpetic recurrence (DALK: 6%, MK: 9%, P = 0.38), and graft failure (DALK: 4%, MK: 5%, P = 0.75) were comparable in both groups.

CONCLUSION

Large diameter (9 mm) DALK yields excellent visual and clinical outcomes in eyes with herpetic corneal scars. In case of intraoperative complications, DALK can be converted to two-piece microkeratome-assisted MK to maximize the refractive benefit of a large diameter graft while minimizing the risk of endothelial failure.

Impact of topographic localization of corneal ectasia on the outcomes of deep anterior lamellar keratoplasty employing large (9 mm) versus conventional diameter (8 mm) grafts

OBJECTIVES

Visual and topographic outcomes of large (9.0 mm) versus conventional (8.0 mm) deep anterior lamellar keratoplasty (DALK) for the treatment of keratoconus (KC) were compared in relation to the different localization of the corneal ectasia (within or beyond the central 8.0 mm).

METHODS

This is a retrospective, comparative case series. Preoperatively, the topographic extension of the conus was calculated by measuring the distance from the geometric center of the cornea and the outermost point of the corneal ectasia (ectasia <8.0 mm, group A; ectasia ≥8.0 mm, group B). DALK was performed using both small grafts (8.0 mm, group 1) and large grafts (9.0 mm, group 2). Best-corrected visual acuity and topographic astigmatism were evaluated preoperatively (T0) and postoperatively after complete suture removal (1 year, T1).

RESULTS

Data from 224 eyes of 196 patients (mean age 37.6 ± 15.1 years) were evaluated. Topographic astigmatism improved from T0 to T1 (4.94 ± 2.92 diopters (D) [95% CI, 4.56-5.33] vs 4.19 ± 2.45 D [95% CI, 3.87-4.51], p = 0.001). There was no significant difference in postoperative topographic cylinder between group 1 and group 2 when considering eyes with corneal ectasia <8.0 mm (group 1 A, 4.15 ± 2.19 D [95% CI, 3.64-4.66] vs group 2 A, 3.65 ± 2.13 D [95% CI, 2.92-4.38], p = 0.14); conversely, the difference was significant considering eyes with corneal ectasia ≥8.0 mm (group 1B, 4.74 ± 2.90 D [95% CI, 4.09-5.38] vs group 2B, 3.68 ± 1.94 D [95% CI, 3.10-4.26], p = 0.02).

CONCLUSIONS

Large 9.0-mm DALK provided better anatomical outcomes compared to conventional 8.0-mm DALK, particularly in eyes with corneal ectasia extending beyond the central 8.0 mm.

DALK rejection following vaccination against SARS-CoV-2: 2 case reports

PURPOSE

To report two cases of deep anterior lamellar keratoplasty (DALK) rejection occurring in association with SARS-CoV-2 vaccination.

METHODS

Two patients with prior history of DALK developed immunologic rejection after SARS-CoV-2 vaccination. The first patient, a 15-year-old girl, had a stromal and sub-epithelial rejection nine days after receiving the first dose of the SARS-CoV-2 vaccine BBV152(COVAXINTM, Bharat Biotech, India). The second patient, an 18-year-old male, had a stromal rejection 13 days after receiving the second dose of the ChAdOx1 SARS-CoV-2 vaccine (COVISHIELDTM, Serum Institute of India, India).

RESULTS

Both patients received frequent topical corticosteroids. The first patient recovered within four weeks and the second patient recovered within two weeks of initiating therapy. Both patients experienced complete resolution of corneal edema and had improvement in their visual acuity.

CONCLUSIONS

DALK rejection is a rare but distinct possibility in patients following SARS-CoV-2 immunization. Further studies are required before establishing clear guidelines regarding risk, follow-up and treatment strategies in such a scenario.

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.

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.

High Astigmatism After Conventional Diameter Deep Anterior Lamellar Keratoplasty in Keratoconus Can Be Successfully Managed With Repeat Wide Diameter Deep Anterior Lamellar Keratoplasty

PURPOSE

The aim of this study was to describe a new surgical technique to replace a conventional diameter (≤8 mm) deep anterior lamellar keratoplasty (DALK) graft with associated high astigmatism refractory to corneal-based astigmatic procedure/intolerance to contact lenses with a larger diameter (≥9 mm) DALK graft to improve best spectacle-corrected visual acuity (BSCVA).

METHODS

Two eyes from 2 keratoconic patients at Southend University Hospital between December 2019 and June 2021 with a minimum follow-up of 17 months were evaluated. The primary outcome of interest was Snellen BSCVA with a secondary outcome of topographic cylinder.

RESULTS

Patient 1 had undergone initial 8 mm diameter DALK, with residual keratometric astigmatism of nearly 12 diopters (D) postoperatively despite numerous astigmatic interventions, with a BSCVA of 6/60, before undergoing 9 mm diameter repeat modified DALK. After suture removal and subsequent in-the-wound blunt manual relaxing incisions, the patient had a final keratometric astigmatism of 3.5 D, manifest refraction of plano/-3.50 × 175, and a BSCVA of 6/9. Patient 2 had undergone initial 7.75 mm diameter DALK, with residual keratometric astigmatism of 10.5 D with a BSCVA of counting fingers. The patient underwent 9 mm repeat modified DALK with final residual keratometric astigmatism of 3.1 D after suture removal, manifest refraction of -1.00/-2.75 × 25, and BSCVA of 6/9.

CONCLUSIONS

Wide diameter DALK (>9 mm) is effective in the management of conventional diameter DALK (≤8 mm) associated high astigmatism in keratoconus. Creation of a peripheral posterior stromal shoulder also allows safe further titration of residual astigmatism if needed.

Ex Vivo Evaluation of a Pressure-Sensitive Device to Aid Big Bubble Intrastromal Dissection in Deep Anterior Lamellar Keratoplasty

Purpose

To develop and perform ex vivo testing for a device designed for semiquantitative determination of intracorneal dissection depth during big bubble (BB) deep anterior lamellar keratoplasty.

Methods

A prototype device connected to a syringe and cannula was designed to determine depth of intrastromal placement based on air rebound pressure emitted by a software controlled generator. Ex vivo testing of the device was conducted on human corneas mounted on an artificial anterior chamber in three experiments: (1) cannula purposely introduced at different depths measured with anterior segment optical coherence tomography, (2) cannula introduced as per the BB technique, and (3) simulation of the BB technique guided by the device.

Results

A positive pressure differential and successful BB were observed only when the cannula was positioned within 150 microns from the endothelial plane. In all successful BB cases (21/40), a repeatable increase in tissue rebound pressure was detected, which was not recorded in unsuccessful cases. The device was able to signal to the surgeon correct placement of the cannula (successful BB) in 16 of 17 cases and incorrect placement of the cannula (unsuccessful BB) in 8 of 8 cases (94.1% sensitivity, 100% specificity).

Conclusions

In our ex vivo model, this novel medical device could reliably signal cannula positioning in the deep stroma for effective pneumatic dissection and possibly aid technical execution of BB deep anterior lamellar keratoplasty.

Translational Relevance

A medical device that standardizes big bubble deep anterior lamellar keratoplasty could increase the overall success rate of the surgical procedure and aid popularization of deep anterior lamellar keratoplasty.

Trends in Corneal Transplantation in a Tertiary Hospital in Brazil

PURPOSE

The purpose of this study was to analyze the evolving trends of surgical techniques and indications of corneal transplantation (CT) at a tertiary hospital in Brazil.

METHODS

The medical records of all patients who underwent CT at the Hospital Oftalmológico de Sorocaba (Sorocaba Eye Hospital) from the Banco de Olhos de Sorocaba (Sorocaba Eye Bank) group in Sorocaba, Brazil, from January 1, 2012, to December 31, 2019, were analyzed. Data regarding age, sex, transplant indication, and surgical technique were collected.

RESULTS

A total of 16,250 CTs were performed. There was a statistically significant decreasing trend of keratoconus-related CT ( P < 0.0001), with rates dropping from 41.7% among all CTs in 2012 to 25.5% in 2019. Penetrating keratoplasty, anterior lamellar keratoplasty, and endothelial keratoplasty (EK) accounted for 59.3%, 27.1%, and 7.8% of the CTs performed in 2012 and 33.3%, 16.4%, and 39.9% in 2019, respectively. A statistically significant decreasing trend was observed for penetrating keratoplasty ( P < 0.0001) and anterior lamellar keratoplasty ( P < 0.0001), whereas EK showed a statistically significant increasing trend during the period ( P < 0.0001). Among EKs, Descemet membrane EK increased statistically significantly from 12.8% in 2012 to 74.4% in 2019 ( P < 0.0001).

CONCLUSIONS

This study shows relevant evolving trends in indications and preferred CT techniques in a tertiary hospital in Brazil.

Comparative Study on the Efficacy of Frozen Amniotic Membrane Transplantation and Lamellar Keratoplasty in the Treatment of Mooren Ulcer

OBJECTIVE

To compare of the clinical efficacy of frozen amniotic membrane transplantation (AMT) and lamellar keratoplasty (LKP) in the treatment of Mooren ulcer.

METHOD

Forty patients (42 eyes) with Mooren's ulcer in our hospital from January 2010 to January 2019 were divided into frozen AMT group (20 eyes) and LKP group (22 eyes). Comparative observation of post-operative best corrected visual acuity (BCVA), corneal epithelial healing time, corneal epithelialization time, ulcer healing, corneal transparency, corneal graft transparency, neovascularization and original disease recurrence were observed.

RESULTS

The average BCVA at post-operative 6 and 12 months in LKP group were significantly lower than AMT group (P < 0.05). The ulcer healing rates in LKP group (63.6) were significantly higher than AMT group (30) (P < 0.05). The corneal epithelialization time of LKP group were 9.55 ± 1.26 days. The corneal epithelial healing time of AMT group were 13.50 ± 2.21 days. Nine cases were corneal graft transparency grade 0, and 13 cases were grade I. Three eyes in AMT group were corneal transparency grade 0, 7 were grade I and 10 were grade II. Corneal neovascularization were observed in 3 eyes in AMT group and 4 eyes in LKP group. The original disease recurrence rates in LKP group (50) were significantly higher than AMT group (20) (P < 0.05). Four cases of primary corneal transplantation failure were observed in LKP group.

CONCLUSION

Lamellar keratoplasty group obtained significantly better BCVA during follow-up and faster healing time than the frozen AMT group while frozen AMT group had lower original disease recurrence rates than LKP group.

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).

Five-year Outcomes of Converted Mushroom Keratoplasty from Intended Deep Anterior Lamellar Keratoplasty (DALK) Mandate 9-mm Diameter DALK as the Optimal Approach to Keratoconus

PURPOSE

To compare the 5-year outcomes of 9-mm-deep anterior lamellar keratoplasty (DALK) for keratoconus with those of conversions to mushroom keratoplasty (MK).

DESIGN

Retrospective cohort study.

METHODS

The setting was the Ospedali Privati Villa Igea, Department of Ophthalmology, Forlì, Italy. The study population consisted of the medical records of all attempted DALK procedures (416 eyes) for the indication of keratoconus performed between January 2012 and January 2018; 68 eyes (16.4%) were converted to MK and analyzed as a separate cohort. The mean follow-up time was 33.8 ± 15.1 months. Procedure(s) consisted of 9-mm DALK and MK (9-mm anterior lamella with 6-mm posterior lamella). Outcome measurements were best-corrected visual acuity (BCVA), refractive astigmatism, and endothelial cell loss (ECL) at 5 years.

RESULTS

Average BCVA at 5 years was 0.06 ± 0.07 in the DALK group and 0.09 ± 0.15 in the MK group (P = .88). Refractive astigmatism following suture removal (all visits later than 12 months) was slightly less in the DALK cohort (5-year DALK = 2.16 ± 1.40 diopter [D]; MK = 3.02 ± 0.89 D; P = .04; mean difference = 0.86 D [95% confidence interval [CI]: 0.71-1.01]). ECL was significantly higher in the MK group than in the DALK group at all follow-up intervals (5-year DALK = 19.36 ± 21.47%; MK = 56.61 ± 15.82%; P < .001). The total all-cause graft failure rate at 5 years was 0.58% for DALK (2 of 348) cases and 5.88% for MK (4 of 68) cases.

CONCLUSIONS

Excellent 5-year visual and clinical outcomes associated with a 2-piece MK in cases converted from intended DALK mandate large-diameter DALK (9 mm) as the optimal surgical approach to keratoconus.

A deep learning approach in diagnosing fungal keratitis based on corneal photographs

Fungal keratitis (FK) is the most devastating and vision-threatening microbial keratitis, but clinical diagnosis a great challenge. This study aimed to develop and verify a deep learning (DL)-based corneal photograph model for diagnosing FK. Corneal photos of laboratory-confirmed microbial keratitis were consecutively collected from a single referral center. A DL framework with DenseNet architecture was used to automatically recognize FK from the photo. The diagnoses of FK via corneal photograph for comparing DL-based models were made in the Expert and NCS-Oph group through a majority decision of three non-corneal specialty ophthalmologist and three corneal specialists, respectively. The average percentage of sensitivity, specificity, positive predictive value, and negative predictive value was approximately 71, 68, 60, and 78. The sensitivity was higher than that of the NCS-Oph (52%, P < .01), whereas the specificity was lower than that of the NCS-Oph (83%, P < .01). The average accuracy of around 70% was comparable with that of the NCS-Oph. Therefore, the sensitive DL-based diagnostic model is a promising tool for improving first-line medical care at rural area in early identification of FK.

Corneal graft failure: an update

Corneal graft surgery is one of the most successful forms of human solid-tissue transplantation, and nowadays, there is a worldwide expansion of the surgical volume of corneal grafts. This surgery is continuously evolving, with new surgical techniques and postoperative treatments that have considerably increased the chance of survival for the grafts. Despite the high rate of success, corneal transplantation is still complicated by a relevant risk of graft failure. This study investigates the causes that lead to the failure of the different corneal graft surgical techniques and provides an updated synthesis on this topic. A comprehensive review of the main pathological pathways that determine the failure of corneal grafts is provided, analysing the main risk factors and disclosing the survival rates of the principal form of corneal grafts. Our results revealed that penetrating keratoplasty has higher failure rates than lamellar keratoplasty, with immunological rejection being the leading cause of graft failure, followed by late endothelial failure (LEF) and ocular surface disorders. Postoperative glaucoma and dehiscence of the surgical wound represent other important causes of failure. Endothelial keratoplasty showed the lowest rates of failure in the mid-term, with LEF, detachment of the graft and primary graft failure representing the most common pathological reasons for failure.

A retrospective study comparing DALK and PKP in the treatment of necrotizing stromal keratitis

PURPOSE

To compare the clinical outcomes of deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PKP) in the treatment of necrotizing stromal keratitis (NSK).

METHODS

A retrospective study of NSK patients who underwent keratoplasty between January 2015 and December 2017 in the Third Xiangya Hospital was carried out. Data including preoperative and postoperative best corrected visual acuity (BCVA), intraocular pressure, graft survival rates, corneal endothelial cell density, corneal topography and thickness were reviewed and analyzed by SPSS 23.0 software.

RESULTS

Fifty patients were involved. Twenty-five patients received DALK, and the other half received PKP. The average follow-up period was 10.28 ± 5.92 months. At the end of the follow-up period, there were no significant differences in postoperative BCVA, recurrence of virus, graft rejection or graft failure between the two groups. There were also no significant differences in average central corneal thickness postoperatively at 3 months. However, the average corneal endothelial cell density at 3 months was significantly higher in the DALK group (2121.12 ± 450.80 cell/mm² in the DALK group versus 1812.16 ± 340.38 cell/mm² in the PKP group, P = 0.009).

CONCLUSION

Both DALK and PKP could increase visual acuity and prevent the progression of NSK. There were no significant differences between DALK and PKP in postoperative BCVA, rate of rejection, graft failure or recurrence rate. DALK significantly reduced the loss of corneal endothelial cells.

Reliability of the Evidence Addressing Treatment of Corneal Diseases: A Summary of Systematic Reviews

Importance

Patient care should be informed by clinical practice guidelines, which in turn should be informed by evidence from reliable systematic reviews. The American Academy of Ophthalmology is updating its Preferred Practice Patterns (PPPs) for the management of the following 6 corneal diseases: bacterial keratitis, blepharitis, conjunctivitis, corneal ectasia, corneal edema and opacification, and dry eye syndrome.

Objective

To summarize the reliability of the existing systematic reviews addressing interventions for corneal diseases.

Data Source

The Cochrane Eyes and Vision US Satellite database.

Study Selection

In this study of published systematic reviews from 1997 to 2017 (median, 2014), the Cochrane Eyes and Vision US Satellite database was searched for systematic reviews evaluating interventions for the management of any corneal disease, combining eyes and vision keywords and controlled vocabulary terms with a validated search filter.

Data Extraction and Synthesis

The study classified systematic reviews as reliable when each of the following 5 criteria were met: the systematic review specified eligibility criteria for inclusion of studies, conducted a comprehensive literature search for studies, assessed risk of bias of the individual included studies, used appropriate methods for quantitative syntheses (meta-analysis) (only assessed if meta-analysis was performed), and had conclusions that were supported by the results of the systematic review. They were classified as unreliable if at least 1 criterion was not met.

Main Outcomes and Measures

The proportion of systematic reviews that were reliable and the reasons for unreliability.

Results

This study identified 98 systematic reviews that addressed interventions for 15 corneal diseases. Thirty-three of 98 systematic reviews (34%) were classified as unreliable. The most frequent reasons for unreliability were that the systematic review did not conduct a comprehensive literature search for studies (22 of 33 [67%]), did not assess risk of bias of the individual included studies (13 of 33 [39%]), and did not use appropriate methods for quantitative syntheses (meta-analysis) (12 of 17 systematic reviews that conducted a quantitative synthesis [71%]). Sixty-five of 98 systematic reviews (66%) were classified as reliable. Forty-two of the 65 reliable systematic reviews (65%) addressed corneal diseases relevant to the 2018 American Academy of Ophthalmology PPPs; 33 of these 42 systematic reviews (79%) are cited in the 2018 PPPs.

Conclusions and Relevance

One in 3 systematic reviews addressing interventions for corneal diseases are unreliable and thus were not used to inform PPP recommendations. Careful adherence by systematic reviewers and journal editors to well-established best practices regarding systematic review conduct and reporting might help make future systematic reviews in eyes and vision more reliable.

Phacoemulsification in eyes with corneal opacities after deep anterior lamellar keratoplasty

To evaluate the maneuverability and efficacy of phacoemulsification and intraocular lens (IOL) implantation in eyes with corneal opacities after deep anterior lamellar keratoplasty (DALK), twelve eyes of 12 patients with mild to moderate corneal opacities after DALK and coexisting cataracts were analyzed retrospectively. Phacoemulsification and IOL implantation assisted with anterior capsule staining, as well as non-invasive optical fiber illumination, were performed on all eyes. No intraoperative or postoperative complications were noted. Mean corrected distance visual acuity (logMAR) improved from 1.24±0.17 to 0.73±0.22. Post-phaco intraocular pressure was maintained between 13 to 20 mm Hg in all cases throughout the follow-up period. Mean endothelial cell density decreased from 2258.42±205.94 to 1906.25±174.23 cells/mm². Phacoemulsification and IOL implantation are safe and valid in eyes with mild to moderate corneal opacities after DALK and coexisting cataracts when assisted with anterior capsule staining and non-invasive optical fiber illumination.

Factors Affecting Formation of Type-1 and Type-2 Big Bubble during Deep Anterior Lamellar Keratoplasty

Purpose: To determine the factors associated with the formation of different types of big bubble (BB) during DALK. Methods: In this retrospective study, 322 consecutive eyes of 307 patients with corneal stromal disorders who underwent DALK between January 2014 and June 2017 were included. Age, sex, corneal pathology, visual acuity, corneal curvature, corneal thickness, and adverse events were recorded. The main outcome measure was the success of BB formation with respect to the corneal pathology. Results: Type-1 BB was achieved in 147 eyes (45.7%), whereas type-2 BB was formed in 109 eyes (33.9%). The overall success rate of BB formation was 82.9%. Type-1 BB formation in keratoconus patients was significantly higher than type-2 BB (83.8% vs 2.6%, p < 0.001). In contrast, type-2 BB formation was significantly higher than type-1 BB (61.0% vs 15.6%, p < 0.001) in patients with corneal scars. Type-1 BB was more likely to be seen in patients with superficial corneal scarring, granular, and lattice dystrophies, while corneas with deep scarring and macular dystrophy had more type-2 BB. The type of bubble was not associated with age and gender of the patients. Conclusions: The overall success of big-bubble (BB) deep anterior lamellar keratoplasty (DALK) depends on the preoperative corneal pathology. Type -1 BB was more commonly seen in keratoconus patients whereas type-2 BB was observed in patients with deep corneal scars and other corneal pathologies affecting deeper layers of corneal stroma.

Etiology of Global Corneal Blindness and Current Practices of Corneal Transplantation: A Focused Review

PURPOSE

The purpose of this focused review was to explore the etiologies of corneal blindness worldwide and compare them with the indications and type of keratoplasties (eg, full-thickness penetrating keratoplasty, anterior lamellar keratoplasty, or endothelial keratoplasty) performed.

METHODS

A literature search of the articles published in the top 10 journals (based on the Altmetrics score) relevant to corneal transplantation within the past 20 years was performed to determine how the focus within corneal transplantation has changed over time. These data were compared with the prevalence and etiology of corneal blindness in each respective region worldwide.

RESULTS

The leading etiologies of corneal blindness worldwide are primarily due to anterior corneal pathology with a normal endothelium, and the prevalence is highest in developing countries. In addition, the number and type of corneal transplantations performed globally indicate that current practices are disproportionately skewed in favor of endothelial keratoplasty, which is targeted for the pathology prevalent in developed countries. Despite the large number of individuals who would benefit from anterior lamellar keratoplasty, this technique seems to be infrequently performed.

CONCLUSIONS

Most corneal blindness worldwide is secondary to anterior corneal pathology because of infections and trauma. However, this does not align with the current trends and practices in the field of corneal transplantation. We discuss potential solutions to address the current leading causes of global corneal blindness, including increasing the number of anterior lamellar keratoplasties performed, using long-term preserved corneas by trained surgeons, and improving eye bank handling and distribution of procured tissues.

Etiology and failure analysis of anterior lamellar keratoplasty

AIM

To analyze indications and reasons for failure of anterior lamellar keratoplasty (ALK).

METHODS

The clinical records were retrospectively reviewed. Main outcome measures included indications for ALK and reasons for failure of ALK.

RESULTS

A total of 434 patients (462 eyes) were treated with ALK at Qingdao Eye Hospital, Shandong Eye Institute from June 1, 2009 to May 31, 2016. The main indications were infectious keratitis (33.3%), keratoconus (23.6%), corneal dystrophy and degeneration (9.8%), Mooren's ulcer (8.4%), corneal neoplasm (7.8%), viral keratitis (6.5%) and regrafting (3.7%). Fungal keratitis accounted for 73.4% in the infectious keratitis cases. ALKs were failed in 36 patients, with the major causes being recurrence of primary diseases (63.9%). The leading causes of graft failure was Mooren's ulcer (36.1%), followed by infectious keratitis (30.6%). Recurrence of fungal keratitis accounted for 81.8% in the failed cases after ALK for infectious keratitis cases.

CONCLUSION

Infectious keratitis and keratoconus are the main indications for ALK, of which fungal keratitis was the major cause of corneal infections. Recurrence of primary disease is the main reason of graft failure after ALK, in which the main primary diseases associated with graft failure are Mooren's ulcer and fungal keratitis.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Cost-Effectiveness Analysis of Corneal Collagen Crosslinking for Progressive Keratoconus

PURPOSE

To evaluate the cost effectiveness of corneal collagen crosslinking (CXL) for progressive keratoconus from the healthcare payer's perspective.

DESIGN

A probabilistic Markov-type model using data from published clinical trials and cohort studies.

PARTICIPANTS

Two identical cohorts, each comprising 1000 virtual patients with progressive bilateral keratoconus, were modeled; one cohort underwent CXL and the other cohort received no intervention.

METHODS

Both cohorts were modeled and evaluated annually over a lifetime. Quality-adjusted life years (QALYs), total cost, disease progression, and the probability of corneal transplantation, graft failure, or both were calculated based on data from published trials and cohort studies. These outcomes were compared between the 2 cohorts. In our base scenario, the stabilizing effect of CXL was assumed to be 10 years; however, longer durations also were analyzed. One-way sensitivity analyses were performed to test the robustness of the outcomes.

MAIN OUTCOME MEASURE

Incremental cost-effectiveness ratio (ICER), defined as euros per QALY.

RESULTS

Assuming a 10-year effect of CXL, the ICER was €54 384/QALY ($59 822/QALY). When we adjusted the effect of CXL to a lifelong stabilizing effect, the ICER decreased to €10 149/QALY ($11 163/QALY). Other sensitivity and scenario analyses that had a relevant impact on ICER included the discount rate, visual acuity before CXL, and healthcare costs.

CONCLUSIONS

Corneal collagen crosslinking for progressive keratoconus is cost effective at a willingness-to-pay threshold of 3 times the current gross domestic product (GDP) per capita. Moreover, a longer stabilizing effect of CXL increases cost effectiveness. If CXL had a stabilizing effect on keratoconus of 15 years or longer, then the ICER would be less than the 1 × GDP per capita threshold and thus very cost effective.

Weighing of risk factors for penetrating keratoplasty graft failure: application of Risk Score System

AIM

To analyze the relationship between the score obtained in the Risk Score System (RSS) proposed by Hicks et al with penetrating keratoplasty (PKP) graft failure at 1y postoperatively and among each factor in the RSS with the risk of PKP graft failure using univariate and multivariate analysis.

METHODS

The retrospective cohort study had 152 PKPs from 152 patients. Eighteen cases were excluded from our study due to primary failure (10 cases), incomplete medical notes (5 cases) and follow-up less than 1y (3 cases). We included 134 PKPs from 134 patients stratified by preoperative risk score. Spearman coefficient was calculated for the relationship between the score obtained and risk of failure at 1y. Univariate and multivariate analysis were calculated for the impact of every single risk factor included in the RSS over graft failure at 1y.

RESULTS

Spearman coefficient showed statistically significant correlation between the score in the RSS and graft failure (P<0.05). Multivariate logistic regression analysis showed no statistically significant relationship (P>0.05) between diagnosis and lens status with graft failure. The relationship between the other risk factors studied and graft failure was significant (P<0.05), although the results for previous grafts and graft failure was unreliable. None of our patients had previous blood transfusion, thus, it had no impact.

CONCLUSION

After the application of multivariate analysis techniques, some risk factors do not show the expected impact over graft failure at 1y.

Late Stromal Rejection in Deep Anterior Lamellar Keratoplasty: A Case Series

PURPOSE

To report a series of 4 cases (3 patients) with late stromal graft rejection 32 to 46 months after an uneventful deep anterior lamellar keratoplasty (DALK).

METHODS

Three patients (4 eyes), who had undergone an uneventful DALK for keratoconus (3 eyes) and infectious keratitis (1 eye) 32 to 46 months previously presented with a history of ocular discomfort and redness, with reduced visual acuity in 3 eyes. In all cases, all sutures had been removed at least 18 months previously. On examination, there was superficial and in 2 eyes deep neovascularization. In 2 eyes, the vessels extended within the interface between the donor and host corneas. The stroma of the donor cornea adjacent to the areas of vascularization was edematous. A diagnosis of stromal graft rejection was made, and the patients were administered intensive topical corticosteroids.

RESULTS

All eyes responded well to treatment, becoming more comfortable, with decreasing redness, reversal of corneal edema, and return of prerejection best corrected visual acuity with up to 18 months follow-up. The patients continued to receive tapering dosage of topical corticosteroid for 12 months. In 1 eye topical steroids were reintroduced at 13 months because of a further rejection episode.

CONCLUSIONS

These cases of late stromal rejection after DALK provide clinical evidence that donor keratocytes may persist in such lamellar grafts for extended periods and that patients should be warned that rejection may occur years after surgery.

Surgical outcome of deep anterior lamellar keratoplasty with air-assisted manual dissection for corneas with previous inflammation or fibrosis

PURPOSE:

To report our experience in air-assisted manual dissection deep anterior lamellar keratoplasty (DALK) for the treatment of corneal scar with previous inflammation and fibrosis.

MATERIALS AND METHODS:

We retrospectively reviewed the medical history of 21 patients (male:female = 13:8 mean age 41.9 years old) with corneal pathology from previous infection and inflammation. Trephination diameter ranged from 7.0 to 8.0 mm, and the graft was oversized by 0.25–0.50 mm. Debulking technique was performed to expose Descemet's membrane after filling stroma with air. Starting from postoperative 3 months, selective suture removal was performed to reduce corneal astigmatism.

RESULTS:

The mean follow-up period was 59.9 ± 19.8 (20–96) months. Intraoperative microperforation occurred in 2 eyes (9.5%); however, there was no shift to penetrating keratoplasty. Air-bubble tamponade was performed in 7 eyes (33.3%) for postoperative gapping of the graft. There were 2 failed grafts (9.5%) due to corneal ulcer while all the other grafts remained clear throughout follow-up. The mean preoperative best-corrected visual acuity (BCVA) was 1.84 ± 0.66 logMAR, which improved to 0.74 ± 0.63 (P < 0.01). The average sphere power was − 0.88 ± 3.88 diopter (D), average cylinder power 3.03 ± 1.46D, and average endothelial count 1877 ± 375 cells/mm².

CONCLUSION:

In severe ocular surface diseases, big-bubble technique frequently failed to separate predescemtic plane; however, it effectively created air-filled stroma which was easier to remove. Although BCVA was suboptimal due to ocular surface disorders, graft survival and clarity rate is high, justifying the application of DALK in these cases.

Sequential Bilateral Corneal Transplantation and Graft Survival

PURPOSE

To investigate graft survival and rejection following sequential bilateral corneal transplantation.

DESIGN

Retrospective cohort study.

METHODS

The study included patients with Fuchs endothelial dystrophy (FED), pseudophakic bullous keratopathy (PBK), or keratoconus who had undergone a penetrating keratoplasty (PK), endothelial keratoplasty (EK), or deep anterior lamellar keratoplasty (DALK) between 1999 and 2012. The main cohort included patients who had received a first transplant in both eyes for the same indication and a control cohort patients who had undergone a unilateral first corneal transplant. Main outcome measures were graft rejection or failure at 5 years.

RESULTS

A total of 11 822 patients were included, of whom 9335 had a unilateral and 2487 bilateral corneal transplantation. For patients with FED (P < .005) and KC (P = .03) but not PBK (P = .19), a transplant in the second eye was associated with a 50% reduction in risk of graft failure within 5 years in the first eye (FED: hazard ratio [HR] 0.47, 95% confidence interval [CI]: 0.34-0.64; KC: HR 0.50, 95% CI: 0.24-1.02). For FED this was dependent on the type of transplant (EK: HR 0.30, 95% CI: 0.17-0.52; PK: HR 0.61, 95% CI: 0.42-0.88). We found no association between a transplant in the second eye and a rejection episode in the first eye (KC P = .19, FED P = .39, PBK P = .19).

CONCLUSION

For FED and KC, a transplant in the second eye was associated with a reduced risk of graft failure in the first eye, independent of inter-transplant time. For FED this effect was pronounced following an EK in the first eye, where the risk of failure was reduced by 70%.