Giorgio Paganoni

Limbal Stem-Cell Therapy and Long-Term Corneal Regeneration

BACKGROUND Corneal renewal and repair are mediated by stem cells of the limbus, the narrow zone between the cornea and the bulbar conjunctiva. Ocular burns may destroy the limbus, causing limbal stem-cell deficiency. We investigated the long-term clinical results of cell therapy in patients with burn-related corneal destruction associated with limbal stem-cell deficiency, a highly disabling ocular disease. METHODS We used autologous limbal stem cells cultivated on fibrin to treat 112 patients with corneal damage, most of whom had burn-dependent limbal stem-cell deficiency. Clinical results were assessed by means of Kaplan-Meier, Kruskal-Wallis, and univariate and multivariate logistic-regression analyses. We also assessed the clinical outcome according to the percentage of holoclone-forming stem cells, detected as cells that stain intensely (p63-bright cells) in the cultures. RESULTS Permanent restoration of a transparent, renewing corneal epithelium was attained in 76.6% of eyes. The failures occurred within the first year. Restored eyes remained stable over time, with up to 10 years of follow-up (mean, 2.91+/-1.99; median, 1.93). In post hoc analyses, success--that is, the generation of normal epithelium on donor stroma--was associated with the percentage of p63-bright holoclone-forming stem cells in culture. Cultures in which p63-bright cells constituted more than 3% of the total number of clonogenic cells were associated with successful transplantation in 78% of patients. In contrast, cultures in which such cells made up 3% or less of the total number of cells were associated with successful transplantation in only 11% of patients. Graft failure was also associated with the type of initial ocular damage and postoperative complications. CONCLUSIONS Cultures of limbal stem cells represent a source of cells for transplantation in the treatment of destruction of the human cornea due to burns.

Acanthamoeba keratitis with perforation after corneal crosslinking and bandage contact lens use

A 32-year-old man with keratoconus developed corneal melting 5 days after riboflavin/ultraviolet-A corneal collagen crosslinking (CXL). Corneal scraping was positive for Acanthamoeba. The patient was unaware that he was wearing a bandage contact lens and repeatedly rinsed his face and eyelids with tap water. Because of corneal perforation, a large therapeutic keratoplasty à chaud was performed. Although CXL is considered a safe procedure, this case emphasizes the potential risks. We discuss the potential effects of deepithelialization, contact lens placement, instillation of topical nonsteroidal antiinflammatory drugs and anesthetic agents, and the possible role of apoptosis when performing CXL treatment for keratoconus.

Modified big-bubble technique compared to manual dissection deep anterior lamellar keratoplasty in the treatment of keratoconus

To evaluate the clinical findings and results of manual dissection deep anterior lamellar keratoplasty (DALK) compared to a modified big‐bubble DALK technique in eyes affected by keratoconus.

Deep anterior lamellar keratoplasty using an original manual technique

Aims To evaluate the clinical findings and visual outcomes of deep anterior lamellar keratoplasty (DALK) using an original manual dissection technique. Methods 288 eyes (268 patients) with corneal pathologies without endothelial involvement were treated by DALK using an original manual dissection technique guided by a calibrated knife incision based on ultrasonic pachimetry values. Clinical records were examined retrospectively at 2 months, 6 months, 1 year and 2 years. The following outcomes were measured: visual acuity, topographic parameters, endothelial cell density and recipient stromal residue thickness. Results At the 2-year postoperative follow-up, the mean logarithm of the minimum angle of resolution best spectacle corrected visual acuity (BSCVA) was 0.131±0.087 and topographic astigmatism was 2.87±1.57 diopters. In 12 cases (4.2%) a perforation of Descemets membrane required conversion of the procedure to penetrating keratoplasty. Mean optical coherence tomography (OCT) residue thickness (measured in 82 eyes with OCT Visante) was 31.63±24.57 μm; lower values of recipient residue thickness were significantly associated with higher BSCVA (Spearman coefficient 0.635, p< 0.001). Conclusion DALK using a dry manual dissection technique provides visual, refractive and clinical results comparable to other deep lamellar techniques. Eyes with lower values of recipient residue thickness are associated with better visual acuity.

Severe keratitis following corneal cross‐linking for keratoconus

performed and the patient underwent proton beam radiotherapy. Two years after proton beam radiotherapy, the tumour thickness was 3.5 mm but the patient developed a recurrent vitreous haemorrhage and neovascular glaucoma requiring enucleation. Pathological examination showed a partially necrotic choroidal melanoma of epithelioid cell type, with vascular hyalinization from the radiotherapy. The mitotic count was 1 ⁄ 40 high power fields. Numerous macrophages were seen. The sclera adjacent to the tumour showed collagen degeneration and calcification (Fig. 2). Apical tumour recurrence after ruthenium plaque radiotherapy is rare, even with eccentric plaque placement (Damato et al. 2005; Lommatzsch et al. 2000; Summanen et al. 1993). This case therefore raises the possibility that treatment failure occurred because of intrascleral calcification beneath the tumour. We suggest that this finding should prompt a higher dose of brachytherapy or an alternative form of radiotherapy, such as proton beam radiotherapy.

Bilateral Acanthamoeba keratitis with late recurrence of the infection in a corneal graft: A case report

Purpose To report a case of bilateral Acanthamoeba keratitis with late, atypical recurrence after penetrating keratoplasty à chaud. Methods A 23-year-old contact lens wearer was treated for bilateral Acanthamoeba keratitis and underwent penetrating keratoplasty in the right eye for descemetocele with impending risk of perforation. The postoperative course was uneventful and topical steroids were combined with neomycin and propamidine. Two months after the operation in the right eye the patient presented with active infection in the left eye. One month later recurrence appeared in the right eye, as a central corneal infiltrate in the graft. Results Recurrences in both eyes were successfully treated with a combination of hexamidine and neomycin, and with polyhexamethylene biguanide respectively. The right eye was regrafted three months after the recurrence and penetrating keratoplasty was done two years later in the left eye. Both grafts were successful and remained clear. There has been no further recurrence in the long-term follow-up. Conclusions Recurrence of Acanthamoeba keratitis after penetrating keratoplasty à chaud may occur even several months after the operation and the manifestation may be atypical. Current antiamoebal therapy was effective and regrafting in the quiet eye was successful.

Corneal collagen cross-linking in paediatric patients affected by keratoconus

Background/aims To evaluate the effectiveness of corneal collagen cross-linking (CXL) in paediatric patients. Methods Fifty-two eyes of 43 paediatric patients with progressive keratoconus were enrolled in a prospective cohort study. Corneal CXL was performed using a conventional technique with instillation of 0.1% riboflavin solution containing dextran 20% for 30 min during the soaking phase and during the 30 min ultraviolet A irradiation (3 mW/cm2). Visual outcomes, topographic keratometry, maximum keratometry (K-max), refractive astigmatism, demarcation line and endothelial cell density were measured postoperatively. Results A significant decrease of K-max from 59.30±7.08 to 57.07±6.46 (p<0.001) was observed 2 years after treatment. Uncorrected visual acuity improved from 0.59±0.41 LogMAR (logarithm of the minimum angle resolution) to 0.46±0.33 LogMAR (p=0.06) 2 years after the procedure, while best spectacle corrected visual acuity improved from 0.17±0.11 LogMAR to 0.15±0.12 LogMAR (p=0.17). Twenty-five eyes had K-max values of 60 dioptres (D) or greater. In this subgroup, K-max significantly decreased from 64.94±4.99 D to 62.25±4.42 D at 2 years (p<0.001). The demarcation line of the CXL treatment had a mean value of 249±74 µm and did not show a significant correlation with K-max flattening (Spearman r=0.019, p=0.899). Endothelial cell density remained stable 2 years after the procedure, changing from 2800±363 to 2736±659 cells/mm2 (p=0.90). Conclusion CXL is an effective treatment for avoiding keratoconus progression in paediatric patients. The procedure is safe and successful in stabilising keratoconus in eyes with more advanced forms of the disease, characterised by topographic K-max values greater than 60 D.

Response to "Pachymetry-Guided Intrastromal Air Injection ("Pachy-Bubble") for Deep Anterior Lamellar Keratoplasty: Results of the First 110 Cases".

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Outcomes of Air Injection Within 2 mm Inside a Deep Trephination for Deep Anterior Lamellar Keratoplasty in Eyes With Keratoconus

WE WOULD LIKE TO CONGRATULATE BUSIN AND ASSOCIates for their attempt at standardizing deep anterior lamellar keratoplasty in their work titled ‘‘Outcomes of Air Injection Within 2 mm Inside a Deep Trephination for Deep Anterior Lamellar Keratoplasty in Eyes With Keratoconus.’’ The manuscript highlights the importance of performing pneumodissection in the deep stroma, which had already been elegantly described by the same group in a previous paper using intraoperative anterior segment optical coherence tomography. The same concepts have been applied in 2 similar techniques used by Ghanem and associates and our group, in which a diamond blade incision set at a specified depth is used as a guide for reaching a deep stromal plane during pneumodissection, which is performed after advancing the air injection cannula toward the central cornea. These techniques rely on the assumption that as the cannula advances, the cannula remains in the deep cornea. In a section of the manuscript, the authors imply that in the techniques described by Ghanem and associates and Knutsson and associates, the pachymetric measurements for the precalibrated diamond knife incision are performed using the ‘‘use of central or paracentral pachymetric values.’’ In our opinion, this phrase is imprecise, as the pachymetric measurements are indeed paracentral (located approximately 1 mm inside the trephination groove) but are localized in the precise area in which the precalibrated incision will be made. The main novelty of the approach described by Busin and associates is the concept of performing pneumodissection with a slight advancement of the cannula (only 2 mm) starting from a deep pachymetry-guided peripheral trephination. It would be interesting to compare the 2 different approaches in a prospective study involving only inexperienced surgeons in both a laboratory and clinical setting in order to establish which techniques can yield higher success rates of bubble formation.