The usefulness of lutein/trypan blue vital dye for the staining of corneal endothelium: a pilot study on DMEK pretreated tissues

PURPOSE

The study aims to evaluate the usefulness of lutein/trypan blue vital dye for the staining of corneal tissues and endothelium-Descemet membrane (EDM) for Descemet membrane endothelial keratoplasty (DMEK).

METHODS

Sixteen human corneal tissues (Eye Bank, Rome, Italy) were used. Corneal endothelium was tested at 25 s (T0), 1 min (T1), 2 min (T2), and 4 min (T4) from dye addition. Staining intensity and cell counting were compared. Stripped EDM was analyzed for selected apoptotic (AP, caspases, BCL2, BAX) and differentiation (VEGF-A, TGF-β1RI, SMAD3/7, SMA) targets and changes in target expression. Protein extracts were analyzed through SDS-PAGE/IB.

RESULTS

Although trypan blue staining produced the same color intensity of lutein/trypan blue dye in half the time, lutein/trypan blue reached a good and adequate color intensity at T4, which persisted even on excised and washed EDM grafts. Lutein/trypan blue-stained EDM showed a reduced number of blue-stained cells and AP immunoreactivity was significantly reduced in the same samples. An increased BCL2 transcript and a reduced BAX transcript were detected in lutein/trypan blue-stained EDM. No significant changes were observed for the main effector caspases (3/9) upon both treatments and the target genes representative of endothelial cell trans-differentiation (TGF-β1RI, SMAD3/7, SMA). A trend in vascular endothelial growth factor (VEGF-A) regulation was observed in lutein/trypan blue-treated EDM grafts.

CONCLUSION

Obtained results suggest that lutein/trypan blue dye deserves attention in the DMEK field and support the potential routine use of this dye as a valid alternative to trypan blue for all procedures devoted to the assessment of endothelial cell viability and visualization of EDM graft before DMEK grafting.

The Management of Dry Eye Disease: Proceedings of Italian Dry Eye Consensus Group Using the Delphi Method

Dry eye disease (DED) is a highly prevalent, chronic and progressive condition that affects 5-33% of the world's adult population [...].

The “Topography” of Glaucomatous Defect Using OCT and Visual Field Examination

Aim

To describe the modifications in the superior and inferior retinal nerve fiber layer (RNFL) thickness regarding the distribution of the VF defects for the horizontal meridians in glaucomatous patients and the differences in the RNFL thickness topography between glaucomatous and healthy subjects.

Methods

One hundred twenty eyes of 91 patients affected by glaucoma and 94 eyes of 51 normal patients were retrospectively reviewed. Computerized 30°VF (Octopus G1 Dynamic strategy) and optical coherence tomography (OCT) ONH and 3D disk analysis were performed in all cases. The RNFL thickness measures analyzed in both groups were superior-nasal (SN), superior-temporal (ST), inferior-nasal (IN), and inferior temporal (IT) sectors. The VFs were classified according to the distribution of the VF defect as for the horizontal meridian in the pattern deviation plot as superior, inferior, predominantly superior, or predominantly inferior.

Result

In the glaucomatous group, 78 eyes (65%) showed a predominantly superior VF defect, while 38 eyes (32%) showed a predominantly inferior VF defect. Fifty-six eyes (46.7%) presented an exclusively superior, and 27/120 eyes (22.5%) presented an exclusively inferior VF defect. In the control group, the thickest RNFL sector was IT. The ST sector showed the thickest RNFL in presence of an exclusive superior VF defect. In case of an exclusive inferior VF defect, the thickest RNFL was the IT sector. VF showing superior defect presented a more altered MD than the VF with an inferior defect.

Conclusion

Glaucomatous damage affects both the superior and inferior neural rim almost simultaneously. However, the neural rim loss seems to be asymmetric, involving the inferior or superior rim depending on the predominant involvement of the superior or inferior hemifield at the VF test. Particularly, the IT sector appears to be the most compromised in glaucomatous eyes. Therefore, the asymmetry between superior and inferior RNFL could support the diagnosis of glaucoma.

How to cite this article

de Paula A, Perdicchi A, Pocobelli A, et al. The “Topography” of Glaucomatous Defect Using OCT and Visual Field Examination. J Curr Glaucoma Pract 2022;16(1):31-35.

To compare corneal confocal microscopy of eyes with Fuchs' endothelial corneal dystrophy after two different endothelial surgeries

PURPOSE

To study the features of corneal confocal microscopy of eyes with Fuchs' endothelial corneal dystrophy (FECD) after successful Descemet stripping automated endothelial keratoplasty (DSAEK) versus Descemet membrane endothelial keratoplasty (DMEK).

METHODS

Thirty-two eyes affected by FECD with corneal oedema requiring a corneal graft were treated with DSAEK (15 eyes) or DMEK (17 eyes). All patients underwent in vivo corneal confocal microscopy (IVCCM) at 6 months postoperatively. We evaluated preoperative and postoperative corrected distance visual acuity (CDVA) and the correlation with IVCCM characteristics.

RESULTS

Using IVCCM, Z-scan curve analysis showed similar subepithelial reflectivity peaks between the two groups (DSAEK 1256 SU ± 514 vs DMEK 1118 SU ± 408, p = 0.411), while the interface reflectivity was significantly higher in the DMEK group (1511 SU ± 357) than in the DSAEK group (1029 SU ± 413, p = 0.002).

CONCLUSION

Comparing the corneal confocal microscopic characteristics after DMEK with those after DSAEK and their correlation with visual outcome at 6 months, we hypothesized that the presence of a third reflectivity peak in the Z-scan curves of DSAEK patients could justify the poorer visual outcome with this endothelial surgery than with DMEK.

Role of Topical Cenegermin in Management of a Cornea Transplant in a Functionally Monocular Patient with Neurotrophic Keratitis and Facial Nerve Palsy: A Case Report

Background

NK is one of the most challenging ocular conditions to treat and it can represent a devastating complication of acoustic neuroma surgery due to the profound corneal anesthesia and concomitant exposure keratopathy caused by seventh nerve palsy. In such cases, cornea surgery should be considered with extreme caution due to the high risk of devastating complications. The purpose of the study is to report the efficacy of a novel human recombinant nerve growth factor (rhNGF)-based ophthalmic treatment in a functionally monocular patient with a recurrence of severe neurotrophic keratitis (NK) on a corneal graft.

Case Presentation

A 24-year-old woman who underwent acoustic neuroma surgery was referred for the assessment of a lagophthalmos and a paracentral corneal ulcer refractory to medical treatment. The patient presented with a large descemetocele, diagnosed as stage 3 NK that required multilayer amniotic membrane transplantation (AMT) and a following optical penetrating keratoplasty (PK). The recurrence of NK on the graft was successfully treated with a cycle of rhNGF (cenegermin 20 µg/mL) eye drops. Due to the complications of a further NK recurrence after treatment discontinuation, a second AMT and PK approach was chosen. A second cycle of treatment with cenegermin was immediately initiated after PK to prevent further recurrences. No postoperative complications were observed and we report a stable situation at 1 year of follow-up.

Conclusion

The case presented here is, to our knowledge, the first report of a treatment with cenegermin for a NK recurrence after PK and suggests that such early medical approach could be evaluated to prevent postoperative complications.

Optimizing pre-Descemet endothelial keratoplasty technique

Pre-Descemet endothelial keratoplasty (PDEK) is an alternative technique to Descemet membrane endothelial keratoplasty (DMEK). The preparation of PDEK tissue by pneumatic dissection is simple and reproducible. The PDEK clamp helps to consistently obtain a type 1 big bubble. The mean size of type 1 big bubble is 7.255 ± 0.535 × 6.745 ± 0.668 mm. The volume of air required to obtain type 1 big bubble is 0.14 to 0.37 mL. Dissection of PDEK tissue can be achieved by trephination or manual excision. Insertion of tissue into the recipient eye can be by injection or pulling. Unfolding techniques used for PDEK are similar to those used in DMEK. Unlike DMEK, PDEK tissue is easier to handle and unscroll and allows use of younger donors. It could help surgeons converting to endothelial keratoplasty, with significant advantages in preparation, handling, and unscrolling in the eye.

Monitoring the microbial contamination of donor cornea during all preservation phases: A prospective study in the Eye Bank of Rome

BACKGROUND

In most European eye banks, human donor corneas are microbiologically tested after storage in organ culture conditions, and the tissues that are free of contamination are distributed for transplantation. In this prospective study, 100 donor corneas were tested for microbial contamination after cold storage, corneal culture and corneal deswelling at the Eye Bank of Rome.

METHODS

Samples of cold storage medium (EUSOL-C), corneal culture medium (TISSUE-C) and deswelling medium (CARRY-C) were tested after three, seven and one days of corneal storage, respectively. The CARRY-C medium, used to transport the cornea to the operation theatre, was retested 1 day after transplantation. The TISSUE-C and CARRY-C media were also tested after removing antimicrobial and antifungal agents using a dedicated device.

RESULTS

We found 67% of the EUSOL-C samples were contaminated mainly by Staphylococcus spp, 14% of TISSUE-C media were contaminated by bacteria and fungi and 3% of CARRY-C media by Staphylococcus spp The analysis performed after removing the antimicrobial and antifungal agents showed growth in three additional TISSUE-C samples (S viridans, S haemolyticus and E faecalis) and one CARRY-C (S cerevisiae and P acnes).

CONCLUSION

Tissue contamination was unexpectedly high on arrival to the eye bank, indicating the need to review and update decontamination procedures during tissue recovery, and renew training for the recovery teams. Storing donor corneas in organ culture conditions significantly reduced the microorganism burden. Using devices to remove antimicrobial and antifungal agents from samples before testing can increase the sensitivity of the standard microbiological method, and thus help further reduce the risk of microbial transmission.

In vivo confocal microscopy of the sclerocorneal limbus after limbal stem cell transplantation: Looking for limbal architecture modifications and cytological phenotype correlations

PURPOSE

To correlate a biomicroscopic evaluation, an in vivo confocal microscopy examination, and impression cytologic findings of the corneal center and sclerocorneal limbus after cultured limbal stem cell transplantation and to test the effectiveness of in vivo confocal microscopy as a diagnostic procedure in ocular surface cell therapy reconstructive surgery.

METHODS

Six eyes of six patients affected by limbal stem cell deficiency after chemical burns underwent ex vivo expanded limbal stem cell transplantation (two eyes) and ex vivo expanded limbal stem cell transplantation with subsequent penetrating keratoplasty (four eyes) to restore corneal transparency. One year after surgery, all patients underwent a biomicroscopic evaluation, central cornea impression cytology to detect cytokeratin 12 (CK12) positivity, and in vivo confocal microscopy of the central cornea and the sclerocorneal limbus to investigate the epithelial cellular morphology, limbal architecture, and corneal inflammation level.

RESULTS

Impression cytology analysis showed CK12 positivity in five of six cases, in concordance with the biomicroscopic evaluation. Confocal microscopy pointed out irregular limbal architecture with the absence of the palisades of Vogt in all cases; the central epithelial morphology presented clear corneal characteristics in three cases and irregular morphology in the remaining three.

CONCLUSIONS

After successful ex vivo expanded limbal stem cell transplantation, in the presence of a complete anatomic architecture subversion, documented by support of in vivo confocal microscopy, the sclerocorneal limbus seemed to maintain its primary function. In vivo confocal microscopy confirmed the procedure was a non-invasive, efficacious diagnostic ocular surface procedure in the case of cell therapy reconstructive surgery.

From discovery to approval of an advanced therapy medicinal product-containing stem cells, in the EU

In 1997, the human corneal epithelium was reconstructed in vitro and transplanted on patients. Later, it became a routine treatment, before regulations considered advanced therapy medicinal products and drugs on the same lines. Manufacturing, before and after good manufacturing practice setting, was established in different facilities and the clinical application in several hospitals. Advanced therapy medicinal products, including stem cells, are unique products with different challenges than other drugs: some uncertainties, in addition to benefit, cannot be avoided. This review will focus on all recent developments in the stem cell-based corneal therapy.

Biological parameters determining the clinical outcome of autologous cultures of limbal stem cells

AIM

Limbal cultures restore the corneal epithelium in patients with ocular burns. We investigated the biological parameters instrumental for their clinical success.

METHODS

We report a long-term multicenter prospective study on 152 patients carrying corneal destruction due to severe ocular burns, treated with autologous limbal cells cultured on fibrin and clinical-grade 3T3-J2 feeder cells. Clinical results were statistically evaluated both by parametric and nonparametric methods.

RESULTS

Clinical outcomes were scored as full success, partial success and failure in 66.05, 19.14 and 14.81% of eyes, respectively. The total number of clonogenic cells, colony size, growth rate and presence of conjunctival cells could not predict clinical results. Instead, the clinical data provided conclusive evidence that graft quality and likelihood of a successful outcome rely on an accurate evaluation of the number of stem cells detected before transplantation as holoclones expressing high levels of the p63 transcription factor. No adverse effects related to the feeder layer have been observed and the regenerated epithelium was completely devoid of any 3T3-J2 contamination.

CONCLUSION

Cultures of limbal stem cells can be safely used to successfully treat massive destruction of the human cornea. We emphasize the importance of a discipline for defining the suitability and the quality of cultured epithelial grafts, which are relevant to the future clinical use of any cultured cell type.

In vivo confocal microscopy in diagnosis of limbal stem cell deficiency

PURPOSE

To correlate in vivo confocal microscopy and impression cytology features of the corneal surface epithelia in patients with clinical features of partial or total limbal stem cell deficiency and to examine the limbal morphology.

DESIGN

Prospective case-control observational study.

METHODS

Twenty eyes of 17 consecutive patients (mean age 53.9 ± 9.2 years) presenting with clinical suspect of limbal stem cell deficiency and 10 eyes of 10 healthy control subjects were enrolled. In vivo confocal microscopy and impression cytology (PAS, cytokeratin 12, and cytokeratin 19) staining were performed in the central cornea. The inter-examination agreement was determined. Confocal microscopy scans were obtained in all patients to assess microscopic structure of the corneoscleral limbus, in all quadrants.

RESULTS

Confocal microscopy and impression cytology agreement in testing the diagnostic hypotheses was high (κ = 0.85). The 2 methods were concordant in 18 out of 20 examined eyes (90%), revealing the presence of just corneal epithelium in 7 cases, just conjunctival epithelium (total limbal stem cell deficiency) in 5 cases, and mixed epithelium in 6 cases (partial limbal stem cell deficiency). Confocal imaging of the limbus revealed normal palisades of Vogt structure and epithelial transition in the healthy eyes while demonstrating a variable degree of alterations, including loss of the limbal palisades and of the normal epithelial mosaic, cystic epithelial changes, and subepithelial fibrosis, in the eyes affected by partial or total limbal stem cell deficiency.

CONCLUSIONS

Confocal microscopy was useful for the noninvasive in vivo diagnosis of limbal stem cell deficiency, with a high degree of concordance with impression cytology, and to detect limbal alterations associated with partial or total conjunctivalization of the cornea.

Evaluation of a new method for the measurement of corneal thickness in eye bank posterior corneal lenticules using Anterior Segment Optical Coherence Tomography

BACKGROUND/AIMS

To preliminarily evaluate the repeatability of central corneal thickness (CCT) measurements performed with Anterior Segment Optical Coherence Tomography (AS-OCT) on eye bank posterior corneal lenticules.

METHODS

Six donor lenticules were created with a 350 μm head microkeratome (Moria, Antony, France). All donor tissues were stored at 4°C in Eusol-C solution (Alchimia S.r.l, Ponte S. Nicolò, Italy), without the anterior cornea lamella. The CCT of each lenticule, maintained in the glass phial, was measured using a commercial AS-OCT instrument (Visante, Carl Zeiss Meditec, Dublin, California, USA) and a specially designed adaptor immediately and 4, 24 and 48 hours after dissection. Immediately after AS-OCT, CCT values were measured with the ultrasound pachymetry method used at the Eye Bank.

RESULTS

The mean donor cornea central thickness was 647±36 μm and 660 ± 38 μm (p=0.001) as measured by AS-OCT and ultrasound, respectively; immediately after dissection, CCT values of posterior lenticules were 235 ± 43 μm and 248 ± 44 μm, respectively (p=0.001). No statistically significant changes in CCT values of donor lenticules were assessed over the 48 h period with both methods. There was a high level of agreement, evidenced by Bland-Altman analysis, between the two methods of pachymetry.

CONCLUSION

AS-OCT, with the corneal tissue in the vial, was revealed to be a repeatable and reliable method for measuring posterior donor lenticule central thickness. Lenticule CCT values measured with the investigational AS-OCT method were on average 10 μm thinner than those measured with the established ultrasound method.

Pre-cut donor tissue for Descemet stripping automated keratoplasty: anterior hinged lamella on versus off

AIMS

To compare two different techniques for preparation of pre-cut lamellar corneal tissue for Descemet stripping automated keratoplasty.

BACKGROUND/METHODS

Eight donor lenticules were created with a full pass of the microkeratome blade, which resulted in a posterior lamella and a free cap (anterior lamella off group (AL-off)). Contralateral donor lenticules were created with an incomplete pass of the microkeratome blade, which resulted in a posterior lamella and a hinged anterior cap (anterior lamella on group (AL-on)). Endothelial cell density, cellular viability and corneal thickness were evaluated before dissection, and 4 and 24 h after dissection.

RESULTS

Average pre-cut endothelial cell density was 2552.25 (+/-105) and 2572.25 (+/-110) cells/mm(2) in the AL-off group and AL-on group, respectively (p=0.7). At 24 h cell density was 2404.87 (+/-74) in the AL-off group (p<0.01) and 2368.74 (+/-148) in the AL-on group (p=0.01). The mean percentage of trypan blue-stained cells was consistently higher in the hinged AL-on group. Corneal thickness increased by approximately 20% in both groups after 24 h cold storage.

CONCLUSION

Eye bank-prepared tissue offers the potential advantage of being screened for mechanical stress damage occurring during the automated dissection.

Effect of antidenaturant drugs on lysozyme deposit formation on soft contact lenses by liquid chromatography--electrochemical detection

The effect of some antidenaturant drugs on the formation of lysozyme deposits on soft contact lenses was investigated by in vitro experiments. Results were obtained which encourage the use of this strategy to reduce lens spoilage. At the same time emphasis is given to the possibility that some functionalities (i.e. lysine groups) present in drug molecules could promote protein adsorption. In order to evaluate at a quantitative level the effectiveness of the drugs used to minimize the formation of deposits on soft contact lenses, a selective method for the determination of adsorbed lysozyme was developed. It is based on the hydrolysis of the 'lens/adsorbed lysozyme' system, followed by high performance liquid chromatography coupled to electrochemical detection of the released tryptophan residues. The lysozyme calibration curve was linear up to 5 mg ml-1 and the detection limit was 5 ng injected.

Two methods of examining protein deposits on hydrophilic contact lenses

Our aim in these studies has been to develop spectroscopic techniques for quantitative analysis of the early phases of protein deposition on soft contact lenses. We produced protein deposition in vitro by soaking lenses in a 0.025% chloral hydrate lysozyme solution at 37 degrees C. Two groups of lenses were so treated: one for 15 days and the other for 6 months. The study of in vivo deposits was carried out on lenses used by healthy wearers. From the same six patients we obtained two consecutive groups of 12 lenses: one group worn for 8 hours and the other group worn for 7 days. We tested the lenses by an indirect (destructive) method (based on a colorimetric assay of amino acid complexes obtained by basic hydrolysis) and by a direct (non-destructive) method consisting of spectrophotometry performed on intact lenses. Using the indirect method we found that the lenses absorbed in vitro for 6 months had lysozyme deposits of 5 +/- 1 micrograms; while the lenses adsorbed for 15 days supplied an average of 0.8 +/- 0.3 micrograms of lysozyme. Lenses worn by healthy volunteers show protein deposition equivalent to a lysozyme quantity ranging from 0.8 to 1.6 micrograms. We found a lower limit of detection with the direct method of approximately 5 micrograms, limiting its applicability.

Use of bendazac lysine to limit protein deposition on soft contact lenses in vitro

We used the heat denaturation of lysozyme to induce the in vitro formation of protein deposits on 60 poly-HEMA contact lenses (38.6% water). Each lens was individually placed in 20 mL of a 0.04% lysozyme solution. The lenses were divided into two equal groups. In the first group (30 lenses), bendazac lysine (100 mg) was added to the lysozyme solution. The second group of lenses was used as control. Quantitative analysis of protein deposits on the lenses of both groups was carried out by a colorimetric test. In the lenses where deposit formation occurred in the presence of bendazac lysine, a mean protein level of 7.17 +/- 3.42 micrograms per lens was found; in the control group the mean value was 30.6 +/- 8.22 micrograms per lens. Student's t-test showed this difference to be significant (P less than 0.001).

[Does a iatrogenic damage caused by dacryography exist?]

This study was aimed at investigating the changes in corneal epithelium caused by dacryocystography. Such changes can be either chemical--from iodate contrast media (iodized oil and water-soluble non-ionic cm)--or physical--from needle or catheter. Twenty-five patients (50 eyes) were studied using BUT, Schirmer tests, biomicroscopy, and pachymetry. Follow-ups immediately after dacryocystography demonstrated superficial keratitis, which was less severe with water-soluble non-ionic cm. Such lesions were hardly ever observed in patients who had been treated with dacriosol ointment on the cornea just before the X-ray exam. Follow-ups at 24 hours showed the superficial keratitis to have disappeared in all patients, independent of the kind of cm employed and of the ophthalmic ointment applied to the cornea.