Impact of COVID-19 on keratoconus patients waiting for corneal cross linking

PURPOSE

Royal College of Ophthalmologist recent guidance recommended delaying cross-linking services during the COVID-19 pandemic. This study investigates the effects of such delays in the delivery of cross-linking services in patients with keratoconus progression.

METHODS

Retrospective observational study of 46 patients with keratoconus progression, whose cross-linking was delayed due to the COVID-19 pandemic. Demographic and clinical details were obtained from assessments on the day of listing, and subsequent review on the day of the procedure. Topographic indices included keratometry of the posterior and anterior corneal surface, maximum keratometry (K_max), thinnest corneal thickness, ABCD progression and progression based on standard criteria recommendations (1.5 D K_max & 20 microns thinning).

RESULTS

A total of 46 eyes were analysed with an average time between being listed for CXL and having the procedure done was 182 ± 65 days. The delay due to COVID-19 was of 3 months. In this time period they had a significant worsening of all keratometric indices and lost almost one line of visual acuity (0.19 ± 0.19 to 0.26 ± 0.18 LogMAR, p: 0.03). Thirty two eyes (70%) demonstrated progression in accordance with the ABCD progression criteria, while 18 eyes (39%) showed either an increase in K_max of more than 1.5D or a thinning in corneal thickness of at least 20 μm.

CONCLUSIONS

The treatment delay for the keratoconus patients caused further progression and vision worsening. We recommend that corneal collagen crosslinking needs to be considered as a high priority intervention.

Biomaterials for corneal endothelial cell culture and tissue engineering

The corneal endothelium is the posterior monolayer of cells that are responsible for maintaining overall transparency of the avascular corneal tissue via pump function. These cells are non-regenerative in vivo and therefore, approximately 40% of corneal transplants undertaken worldwide are a result of damage or dysfunction of endothelial cells. The number of available corneal donor tissues is limited worldwide, hence, cultivation of human corneal endothelial cells (hCECs) in vitro has been attempted in order to produce tissue engineered corneal endothelial grafts. Researchers have attempted to recreate the current gold standard treatment of replacing the endothelial layer with accompanying Descemet's membrane or a small portion of stroma as support with tissue engineering strategies using various substrates of both biologically derived and synthetic origin. Here we review the potential biomaterials that are currently in development to support the transplantation of a cultured monolayer of hCECs.

Staphylococcus aureus Keratitis: Incidence, Pathophysiology, Risk Factors and Novel Strategies for Treatment

Bacterial keratitis is a devastating condition that can rapidly progress to serious complications if not treated promptly. Certain causative microorganisms such as Staphylococcus aureus and Pseudomonas aeruginosa are notorious for their resistance to antibiotics. Resistant bacterial keratitis results in poorer outcomes such as scarring and the need for surgical intervention. Thorough understanding of the causative pathogen and its virulence factors is vital for the discovery of novel treatments to avoid further antibiotic resistance. While much has been previously reported on P. aeruginosa, S. aureus has been less extensively studied. This review aims to give a brief overview of S. aureus epidemiology, pathophysiology and clinical characteristics as well as summarise the current evidence for potential novel therapies.

Antimicrobial Activity of Poly-epsilon-lysine Peptide Hydrogels Against Pseudomonas aeruginosa

Purpose

To determine the antimicrobial activity of poly-epsilon-lysine (pɛK) functionalization of hydrogels against Pseudomonas aeruginosa.

Methods

Antimicrobial activities of pɛK and pɛK+ hydrogels were tested against both keratitis and a laboratory strain of Paeruginosa at a range of inocula sizes, over 4 and 24 hours. The number of viable CFU on pɛK and pɛK+ hydrogels or commercial contact lenses (CL) was investigated. Ex vivo porcine corneas were inoculated with Paeruginosa PAO1 (103 CFU) and incubated with pɛK+ hydrogels or commercial hydrogel CL for 24 hours and the effects of infection determined.

Results

PɛK+ hydrogels showed log reductions in viable CFU compared with pɛK hydrogels for all Paeruginosa strains, depending on inocula sizes and incubation time. After 24 hours pɛK+ hydrogels showed >5 and >7.5 log reduction in CFU compared with commercial hydrogel CL at 103 and 106 CFU, respectively. In an ex vivo porcine corneal infection model, pɛK+ hydrogels led to a significant decrease in viable PAO1 CFU and histologic analysis indicated a decreased infiltration of PAO1 into the stroma.

Conclusions

PɛK+ hydrogels demonstrated enhanced antimicrobial activity versus nonfunctionalized pɛK hydrogels against clinically relevant Paeruginosa strains. PɛK+ hydrogels have the potential to be used as a bandage CL with innate antimicrobial characteristics to minimize the risk of microbial keratitis.

Changes in pupillometry associated with dissipated energy during phacoemulsification

PURPOSE

To investigate the effect of ultrasound level during phacoemulsification on pupil dynamics.

METHODS

Comparative retrospective study on patients who underwent routine cataract surgery at the Royal Liverpool University Hospital. Clinical parameters, anterior chamber measurements, axial length, surgeon grade, time of surgery, level of ultrasound used (cumulative dissipated energy, CDE), intra- and post-operative complications were collected. Pupil diameters were collected before and 4 ± 1 weeks after surgery in static scotopic, mesopic, photopic pupil conditions. Also, pupil dynamic measurements after luminous stimulus were recorded. Changes in static pupil diameters, relative dilation at 3.5 s after luminous stimulus, and time to reach 75% and 95% of maximum dilation were measured.

RESULTS

Forty-eight eyes of 24 patients (13 males) were included with a mean age of 73.1 ± 14.6 years. Mean CDE value was 18.11 ± 10.56. Mean scotopic pupil diameters decreased by 0.24 ± 0.48 mm (p = 0.021) in the operated eye. Significant correlation was found between reduction in scotopic pupil diameter and CDE (p = 0.05). A generalized linear model confirmed that the level of CDE was significantly associated with reduction in scotopic pupil diameter (p = 0.026). Patients who underwent surgeries with lower CDE (0 < CDE ⩽ 10 and 10 < CDE ⩽ 20) did not experience significant changes in scotopic pupil diameter after surgery (p = 0.28 and p = 0.79, respectively) as opposed to those with higher CDE (CDE > 20; p = 0.03).

CONCLUSION

Phacoemulsification cataract surgery and the cumulative dissipated energy may be associated with changes in pupil behaviour.

16S Ribosomal RNA PCR Versus Conventional Diagnostic Culture in the Investigation of Suspected Bacterial Keratitis

Purpose

The purpose of this study was to compare conventional diagnostic culture (CDC) to 16S ribosomal RNA polymerase chain reaction (PCR) analysis for diagnosing bacterial keratitis.

Methods

Samples collected from 100 consecutive patients presenting to the Royal Liverpool University Hospital with bacterial keratitis were processed using CDC and 16S PCR analysis.

Results

The overall detection rate using both methods was 36%. Of these, 72.2% (26/36) were detected by PCR and 63.9% (23/36) isolated by CDC (P = 0.62). Using a combination of both PCR and CDC increased the detection rate for pathogenic bacteria by 13% compared to using CDC alone (P = 0.04). In CDC negative samples, 16S PCR identified more pathogens than CDC in 16S PCR negative samples. Neither order of sample collection nor prior antimicrobial use affected the detection rate.

Conclusions

16S rRNA gene PCR performed in addition to CDC on corneal samples from patients with clinically suspected bacterial keratitis led to additional pathogen detection.

Translational Relevance

16S rRNA gene PCR should be developed to become an additional part of clinical service for patients with bacterial keratitis rather than used in isolation.

Eye bank versus surgeon prepared DMEK tissues: influence on adhesion and re-bubbling rate

Aim

To investigate the difference in adhesion and rebubbling rate between eye bank and surgeon prepared Descemet membrane endothelial keratoplasty (DMEK) tissues.

Methods

Laboratory and clinical retrospective comparative interventional case series. Research corneal tissues were obtained for laboratory investigation. The clinical study involved patients with endothelial dysfunction who underwent DMEK surgery and tamponade with air. Tissues were stripped using a standard DMEK stripping technique (SCUBA) and shipped as prestripped or loaded in a 2.2 intra-ocular lens cartridge with endothelium facing inwards (preloaded) before transporting from the eye bank to the surgeon. For surgeon prepared tissues, all the grafts were stripped in the theatre and transplanted or stripped in the laboratory and tested immediately. Adhesion force and elastic modulus were measured in the centre and mid-periphery in a laboratory ex vivo investigation using atomic force microscopy, while rebubbling rates were recorded in the clinical study.

Results

There was no difference in endothelial cell viability between surgeon or eye bank prepared tissue. Surgeon-stripped DMEK grafts in the laboratory investigation showed significantly higher elastic modulus and adhesion force compared to prestripped and preloaded tissues (p<0.0001). In the clinical data, rebubbling rates of 48%, 40% and 15% were observed in preloaded, prestripped and surgeon-stripped DMEK grafts, respectively. Rebubbling rates were significantly associated with combined cataract surgery (p=0.009) and with time from harvesting the graft to the surgery (p=0.02).

Conclusions

Decreased adhesion forces and elastic modulus in eye bank prepared tissues may contribute to increased rebubbling rates.

Conjunctival Biopsy Site in Mucous Membrane Pemphigoid

PURPOSE

To investigate if there is an association between the location of the conjunctival biopsy site (lesional, perilesional, or nonaffected) and the result of the direct immunofluorescence (DIF) test in patients with suspected mucous membrane pemphigoid (MMP) involving the ocular surface.

DESIGN

Retrospective case series.

METHODS

Records of patients with clinically suspected ocular MMP were reviewed to determine the location of the conjunctival biopsy. Conjunctival biopsy locations were defined as "lesional," "perilesional," and "nonaffected" conjunctiva. The DIF was considered positive when there was deposition of at least 1 of either IgM, IgG, IgA, or C3 at the basement membrane of the specimen; nondiagnostic when only fibrinogen was found at the same location; and negative when none of these features were present.

RESULTS

The records of 41 patients were analyzed. Of these, 32 were eligible to be included in the study. Biopsies were lesional in 22% of cases (7/32), perilesional in 22% (7/32), and from nonaffected conjunctiva in 56% (18/32). DIF results were positive in 14% of lesional biopsies, in 86% of perilesional biopsies, and in 17% of those from nonaffected conjunctiva (P = .003). Perilesional biopsies gave higher positive DIF than lesional biopsies (P = .029).

CONCLUSIONS

Perilesional conjunctival biopsies are associated with an increase in positive DIF results. These results support the need to sample perilesional conjunctival tissue in patients with suspected MMP.

Mass Spectrometry Reveals α-2-HS-Glycoprotein as a Key Early Extracellular Matrix Protein for Conjunctival Cells

Purpose

To determine the composition of extracellular matrix (ECM) proteins secreted by a conjunctival epithelial cell line and to identify components that aid conjunctival epithelial cell culture.

Methods

Human conjunctival epithelial cell line (HCjE-Gi) cells were cultured in serum-free media and their ECM isolated using ammonium hydroxide. Growth characteristics were evaluated for fresh HCjE-Gi cells plated onto ECMs obtained from 3- to 28-day cell cultures. Mass spectrometry was used to characterize the ECM composition over 42 culture days. Cell adhesion and growth on pre-adsorbed fibronectin and α-2-HS-glycoprotein (α-2-HS-GP) were investigated.

Results

Day 3 ECM provided the best substrate for cell growth compared to ECM obtained from 5- to 28-day cell cultures. Mass spectrometry identified a predominantly laminin 332 matrix throughout the time course, with progressive changes to matrix composition over time: proportional decreases in matrix-bound growth factors and increases in proteases. Fibronectin and α-2-HS-GP were 5- and 200-fold enriched as a proportion of the early ECM relative to the late ECM, respectively. Experiments on these proteins in isolation demonstrated that fibronectin supported rapid cell adhesion, whereas fibronectin and α-2-HS-GP both supported enhanced cell growth compared to tissue culture polystyrene.

Conclusions

These data reveal α-2-HS-GP as a candidate protein to enhance the growth of conjunctival epithelial cells and raise the possibility of exploiting these findings for targeted improvement to synthetic tissue engineered conjunctival substrates.

Free-Floating DMEK in the Host Anterior Chamber: Surgical Management

PURPOSE

To describe a method to visualize and manage a completely detached Descemet membrane endothelial keratoplasty (DMEK) tissue scroll in the anterior chamber.

METHODS

A 56-year-old male patient with pseudophakic bullous keratopathy, who underwent uncomplicated DMEK surgery, had a complete graft detachment diagnosed at 1-week follow-up. The graft was reattached using a new technique, that is, the free-floating graft was stained in the anterior chamber with trypan blue, immediately followed by air injection to separate the host stroma from the dye. The stained DMEK graft was opened by gentle tapping and attached to the host stroma by air tamponade.

RESULT

This technique allowed sufficient staining of DMEK tissue to further evaluate and correct the graft orientation inside the anterior chamber without compromising the stroma. The DMEK graft was attached 1 week after the reattachment procedure. The cornea cleared confirming the functionality of the endothelial cells.

CONCLUSIONS

The technique described may be useful in the cases of complete detachment of DMEK tissue and poor visualization of the DMEK tissue orientation. Staining with trypan blue under a "protective" air bubble can provide sufficient visualization to ensure the unfolding of DMEK tissue and reduce the risk of host stromal staining.

Shotgun sequencing to determine corneal infection

Purpose

To investigate if shotgun-sequencing method could be useful in detailed diagnosis of herpes simplex virus (HSV) infection and compare it with the conventional diagnostic method.

Observations

Using a sterile scraper, the infectious part of the ocular surface was scraped gently and placed on a glass slide for conventional diagnosis using PCR and histology and in RNA stabilizing reagent for shotgun sequencing respectively. Concentration of the DNA was determined using a sensitive fluorescence dye-based Qubit dsDNA HS Assay Kit. Shotgun-sequencing libraries were generated using the NEBNext DNA ultra II protocol. The samples were sequenced on the Illumina NextSeq 500 in high output mode with 2X150 bp paired-end sequencing. Taxonomic and functional profiles were generated.

Conventional diagnostic method suspected herpetic keratitis. The results indicated presence of an amplified product of 92 bp positive HSV-DNA. Conventional diagnostic method detected the presence of Herpes Simplex Virus DNA (type 1). Shotgun sequencing confirmed the diagnosis of HSV along with the taxonomical profiling of the virus. These results were achieved using 1.9 ng/μL of DNA concentration (114 ng in 60 μL) of the total sample volume.

Conclusions and importance

Shotgun sequencing is a hypothesis-free approach that identifies full taxonomic and functional profile of an organism. This technology is advantageous as it requires smaller sample size compared to conventional diagnostic methods.

Antimicrobial Nitric Oxide Releasing Contact Lens Gels for the Treatment of Microbial Keratitis

Microbial keratitis is a serious sight threatening infection affecting approximately two million individuals worldwide annually. While antibiotic eye drops remain the gold standard treatment for these infections, the significant problems associated with eye drop drug delivery and the alarming rise in antimicrobial resistance has meant that there is an urgent need to develop alternative treatments. In this work, a nitric oxide releasing contact lens gel displaying broad spectrum antimicrobial activity against two of the most common causative pathogens of microbial keratitis is described. The contact lens gel is composed of poly-ε-lysine (pεK) functionalized with nitric oxide (NO) releasing diazeniumdiolate moieties which enables the controlled and sustained release of bactericidal concentrations of NO at physiological pH over a period of 15 h. Diazeniumdiolate functionalization was confirmed by Fourier transform infrared (FTIR), and the concentration of NO released from the gels was determined by chemiluminescence. The bactericidal efficacy of the gels against Pseudomonas aeruginosa and Staphylococcus aureus was ascertained, and between 1 and 4 log reductions in bacterial populations were observed over 24 h. Additional cell cytotoxicity studies with human corneal epithelial cells (hCE-T) also demonstrated that the contact lens gels were not cytotoxic, suggesting that the developed technology could be a viable alternative treatment for microbial  keratitis.

A decade of clinical development of PARP inhibitors in perspective

Genomic instability is a hallmark of cancer, and often is the result of altered DNA repair capacities in tumour cells. DNA damage repair defects are common in different cancer types; these alterations can also induce tumour-specific vulnerabilities that can be exploited therapeutically. In 2009, a first-in-man clinical trial of the poly(ADP-ribose) polymerase (PARP) inhibitor olaparib clinically validated the synthetic lethal interaction between inhibition of PARP1, a key sensor of DNA damage, and BRCA1/BRCA2 deficiency. In this review, we summarize a decade of PARP inhibitor clinical development, a work that has resulted in the registration of several PARP inhibitors in breast (olaparib and talazoparib) and ovarian cancer (olaparib, niraparib and rucaparib, either alone or following platinum chemotherapy as maintenance therapy). Over the past 10 years, our knowledge on the mechanism of action of PARP inhibitor as well as how tumours become resistant has been extended, and we summarise this work here. We also discuss opportunities for expanding the precision medicine approach with PARP inhibitors, identifying a wider population who could benefit from this drug class. This includes developing and validating better predictive biomarkers for patient stratification, mainly based on homologous recombination defects beyond BRCA1/BRCA2 mutations, identifying DNA repair deficient tumours in other cancer types such as prostate or pancreatic cancer, or by designing combination therapies with PARP inhibitors.

Use of a corneal impression membrane and PCR for the detection of herpes simplex virus type-1

Purpose. To investigate the use of a corneal impression membrane (CIM) for the detection of herpes simplex virus type 1 (HSV-1) in suspected herpes simplex keratitis (HSK).Methodology. In the laboratory study, swabs and CIMs made from polytetrafluoroethylene were spiked with different concentrations of HSV-1. DNA was extracted and real-time PCR undertaken using two sets of primers. In the clinical study, consecutive patients presenting with suspected HSK were included. For each patient, samples were collected from corneal lesions with a swab and a CIM in random order. Clinical details were collected using a standardized clinical form and patients were categorized into probable, presumed and possible HSK.Results. There was no difference in the performance of both primer sets for all HSV-1 dilutions (P=0.83) using a CIM or between a CIM and a swab (P=0.18). In total, 110 patients were included. Overall, 73 patients (66.4 %) had probable, 20 patients (18.2 %) presumed and 17 patients (15.5 %) possible HSV-1 keratitis. The HSV-1 detection rate was significantly higher using a CIM (40/110, 36.4 %) than a swab (28/110, 25.5 %) (P=0.004). In the probable HSV keratitis group, the detection rate using a CIM was 43.8 % compared to 27.4 % for a swab (P=0.004). The cycle threshold values obtained for the conjunctival swabs were higher than those obtained for the CIMs (P<0.001).Conclusions. In suspected HSK, a CIM is a useful alternative to a swab and more likely to detect the presence of HSV-1.

Preparation of ultrathin grafts for Descemet-stripping endothelial keratoplasty with a single microkeratome pass

We present a technique to achieve ultrathin Descemet-stripping automated endothelial keratoplasty (DSAEK). Using a simple method of controlling artificial anterior chamber pressure and drying the corneal surface, it was possible to thin the donor cornea at a rate of 11 μm a minute. When the donor cornea was between 500 μm and 510 μm, a single pass was made using a 350 μm microkeratome head followed by a peripheral dissection. The resulting mean graft thickness was 83.2 μm ± 14.9 (SD) (range 50 to 98 μm) with a mean peripheral graft edge thickness of 106.8 ± 10.9 μm (range 90 to 120 μm). There were no surgical complications, and all grafts remained attached. This is a reliable method for preparing ultrathin donor corneal lenticules for DSAEK in the operating room or eye bank without using multiple microkeratome heads or risking double passes.

Assessment of the Association Between In Vivo Corneal Biomechanical Changes After Corneal Cross-linking and Depth of Demarcation Line

PURPOSE

To test for an association between stiffening following corneal cross-linking (CXL) and demarcation line depth.

METHODS

Sixty-six eyes of 66 patients treated with CXL for progressive keratoconus were included. Dynamic corneal response parameters (DCRs) were measured with the Corvis ST (Oculus Optikgeräte GmbH; Wetzlar, Germany) on the day of CXL and after 1 month. Demarcation line was measured 4 weeks after CXL. A multivariate general linear model was used to test for an association between the change in DCRs and the ratio between demarcation line depth and the postoperative pachymetry.

RESULTS

The authors found no significant associations between the change in inverse concave integrated radius (1/R) and the demarcation line ratio (P = .46), age (P = .33), sex (P = .11), preoperative maximum keratometry (P = .10), and laterality (P = .82). Similarly, there was no significant correlation between the change in 1/R and the demarcation line ratio (R² = .002 and P = .75). However, there was a significant association between the preoperative values of 1/R and the respective change in 1/R (P < .0001). The change in 1/R was inversely proportional to the patient's preoperative 1/R; stiffer corneas (lower values of 1/R) were less affected than less stiff corneas (R² = .23, P < .0001).

CONCLUSIONS

CXL is associated with changes in DCRs, suggesting a change in corneal biomechanics following CXL. These changes do not appear to be associated with the demarcation line depth. [J Refract Surg. 2019;35(3):202-206.].

Iontophoresis CXL With and Without Epithelial Debridement Versus Standard CXL: 2-Year Clinical Results of a Prospective Clinical Study

PURPOSE

To compare the 2-year follow-up outcomes of three groups of patients with keratoconus treated with transepithelial iontophoresis (I-CXL), iontophoresis with epithelial removal (I-SCXL), and standard epithelium-off (S-CXL) CXL for progressive keratoconus.

METHODS

Sixty eyes of 60 patients treated with CXL for progressive keratoconus were included in this comparative, prospective clinical study. Twenty patients were included in each group (I-CXL, I-SCXL, and S-CXL). Corrected distance visual acuity (CDVA), refraction, corneal topography, Scheimpflug tomography, and aberrometry were assessed at baseline and at 1, 3, 6, 12, and 24 months of follow-up. To assess the long-term safety and efficacy of these treatments, the preoperative values were compared with the values at 24 months of follow-up.

RESULTS

The main outcome of the study was the non-statistically significant difference between the three protocols in induced change in most of the parameters, including visual acuity (P = .665), topographic indexes (all P > .05), and maximum keratometry (P = .611) after 2 years of follow-up. There were no significant differences in the change in refractive error following CXL in all groups or between groups (all P > .05). Conversely, I-CXL induced significantly less corneal thinning (P = .0299 and .0121) and a significantly greater reduction of higher order aberrations and coma (all P < .0001) compared to S-CXL and I-SCXL. All protocols induced a significant increase in visual acuity (S-CXL P = .0004, I-SCXL P = .0045, and I-CXL P = .004).

CONCLUSIONS

The 2-year results of this comparative, prospective clinical study demonstrate the efficacy and safety of I-CXL to treat progressive keratoconus and overcome the limitations of CXL with epithelial debridement. [J Refract Surg. 2019;35(3):184-190.].

Metagenomics in ophthalmology: current findings and future prospectives

Less than 1% of all microorganisms of the available environmental microbiota can be cultured with the currently available techniques. Metagenomics is a new methodology of high-throughput DNA sequencing, able to provide taxonomic and functional profiles of microbial communities without the necessity to culture microbes in the laboratory. Metagenomics opens to a ‘hypothesis-free’ approach, giving important details for future research and treatment of ocular diseases in ophthalmology, such as ocular infection and ocular surface diseases.

Next-generation sequencing for the detection of microorganisms present in human donor corneal preservation medium

Objective

To detect the presence of microorganisms in the storage media of human donor corneas using next-generation sequencing method.

Methods

Seven samples from organ culture (OC) group (Cornea Max, Eurobio, Les Ulis, France) with one control (sterile media without any cornea) and seven samples from hypothermic storage group (Cornea Cold, Eurobio) with one control were used for this study. The corneas were placed in the respective storage media for 14 days before collecting the samples. Storage media (2 mL) from each sample were collected in RNAase-free tubes and shipped for ribosomal RNA sequencing of 16 S and 18 S. Simultaneously, another 1 mL of media sample was used for conventional diagnostic method (CDM) using Bactec instruments.

Results

In both, OC and hypothermic storage and control samples, the most abundant genera were Pseudomonas, Comamonas, Stenotrophomonas, Alcanivorax, Brevundimonas and Nitrobacter. Acidovorax, Acetobacter and Hydrogenophilus were detected mostly in the hypothermic storage group. The most abundant fungal pathogen detected belonged to the genus Malassezia, which was found in both the storage conditions. CDM was negative for microorganisms in all the samples.

Conclusion

Metagenomics provides full taxonomic profiling of the detected genomic material of the organisms and thus has the potential to deliver a much wider microbiological diagnostic approach than CDM. The costs and turn-around time need to be reduced, and; the detection of viable organisms would help this technology to be introduced into routine clinical practice.

Intraobserver reproducibility and interobserver agreement of demarcation line depth measurements following corneal cross linking

PURPOSE

The aim of this study was to evaluate the intraobserver reproducibility of demarcation line depth measurement in keratoconic patients after epithelium-off corneal collagen cross linking and assess the interobserver variability/agreement among examiners of various experience levels.

METHODS

56 eyes of 56 patients undergoing corneal collagen cross linking for progressive keratoconus were enrolled. After 4 weeks, all patients underwent an anterior segment optical coherence tomography (AS-OCT; CASIA SS-1000; Tomey, Nagoya, Japan) in the cross-linked eye by four masked examiners (two medical students (S1 and S2) and two corneal fellows (F1 and F2)) in order to identify and measure the demarcation line depth in experienced and non-experienced users. The intraclass correlation coefficient and the coefficient of variation were calculated. Agreement between raters was evaluated using Bland-Altman plots, intraclass correlation coefficient and weighted-kappa statistics comparing raters in pairs.

RESULTS

The average demarcation line depth of all measurements was 254.34 ± 72.3 μm, varying from 84 to 459 μm. The intraclass correlation coefficient evaluating the reproducibility of measurements for F1 was 0.9379 (95% confidence interval (CI) =0.9035-0.9619), for the second (F2), it was 0.9837 (95% confidence interval = 0.9743-0.9901), while intraclass correlation coefficient between medical students was calculated 0.844. The overall intraclass correlation coefficient among all four observers was 0.8706 (95% confidence interval = 0.8061-0.9185). The coefficient of variation for repeated measurements was 5.981 μm (95% confidence interval = 3.966-7.471) and 3.312 μm (95% confidence interval = 2.468-3.981) for F1 and F2 raters, respectively. The percentage of demarcation line detection was 90.32%.

CONCLUSION

The reproducibility of demarcation line measures although very good (intraclass correlation coefficient > 0.9), yielded a difference between the two experienced raters. Furthermore, the novice raters did not reach an excellent level of agreement with the expert ones showing greater variability in their recordings.

Functional Staging of Corneal Neovascularization Using Fluorescein and Indocyanine Green Angiography

Purpose

Corneal neovascularization (CoNV) is a major risk factor for corneal graft rejection and other corneal conditions. The maturity of CoNV is important to guide treatment. This study investigated associations between clinical and angiographic characteristics of CoNV.

Methods

In a prospective cross-sectional study patients with CoNV of variable but known duration and etiology were included. All cases were clinically staged according to a simplified three-grade scale as active, inactive, and regressed and assessed using color photography, anterior-segment optical coherence tomography, and fluorescein and indocyanine green (ICG) angiography. Outcome parameters included age and depth of CoNV, perfusion times and time to leakage of fluorescein and ICG.

Results

Forty eyes of 39 patients with CoNV were included, active (14), inactive (22), and regressed CoNV (4). There were significant associations between the time to fluorescein or ICG leakage and clinical staging of CoNV (R² = 0.24; P = 0.0011, and R² = 0.3; P = 0.0001). In addition, there was a significant association between the time to fluorescein leakage and the age of CoNV (R² = 0.32; P = 0.0002). ICG leakage within 10 minutes was observed significantly more frequently in active than the inactive group and was not observed in regressed cases (P < 0.0001).

Conclusions

Simplification of the staging of CoNV to active, inactive, and regressed to is significantly associated with the time to extravascular leakage of fluorescein and indocyanine and may be useful to guide the selection of appropriate treatments.

Translational Relevance

The association between clinical and angiographic characteristics of CoNV may provide guidance to the treatment approaches.

Descemet Membrane Endothelial Keratoplasty - Complication and management of a single case for tissue preparation and graft size linked to post-op descemetorhexis disparity

Purpose

To report the management of an intraoperative complication during large (9.5 mm) ultra-thin Descemet Stripping Automated Endothelial Keratoplasty (UT-DSAEK) surgery in a patient with a large area of dysfunctional endothelium.

Observations

A single case study of an 89 y/o male with a history of Fuchs corneal endothelial dystrophy is presented. The patient was listed for a large UT-DSAEK, but due to an intraoperative complication during graft preparation, an 8.00 mm Descemet membrane endothelial keratoplasty (DMEK) was prepared from the same graft using a standardized SCUBA technique and delivered. Early postoperative examination of the graft showed decentred, residual corneal oedema in the absence of DM detachment and a well-formed anterior chamber. The endothelial graft was found attached after 3 months and the corneal oedema was cleared. After 5 months, the patient's BSCVA was recorded at 6/6(20/20) in the left eye, but complained of mild discomfort. A circular ring of corneal oedema was observed around the graft and decentralization of the transplanted graft was observed. Endothelial cell density (ECD) of the central cornea at 5th month was 1506 cells/mm² at a focal depth of 496 μm with some polymegathism.

Conclusions

and importance: It is possible to prepare DMEK starting from a failed DSAEK graft. Thickness map on corneal tomography could be a useful tool after DMEK for checking graft centration, function, and corneal recovery indirectly. It is recommended to only maintain a small distance between the descemetorhexis area and the size of the endothelial graft.