Augusto Pocobelli

In Vivo Analysis of Stromal Integration of Multilayer Amniotic Membrane Transplantation in Corneal Ulcers

PURPOSE To evaluate integration of amniotic membrane into the corneal stroma using laser scanning in vivo confocal microscopy and anterior segment optical coherence tomography (AS-OCT). DESIGN Prospective noncomparative interventional case series. METHODS Twenty-two eyes of 22 consecutive patients (mean age 53.9 ± 9.2 years) presenting with noninfectious corneal ulcers and stromal thinning unresponsive to medical treatment were enrolled. Multiple layers of amniotic membrane were applied over the ulcer bed to fill the ulcer crater and held in place with an overlying amniotic membrane patch, which was anchored to the surrounding cornea with 10-0 nylon interrupted sutures. Outcome measures were healing of the corneal ulcers, corneal morphology and stromal thickness changes at the ulcer site as measured by AS-OCT and surface epithelialization, stromal repopulation, and structural modifications of the amniotic membrane grafts as evaluated by confocal microscopy. RESULTS Follow-up extended to 12 months. Successful result was observed in 20 of 22 eyes (90.9%). AS-OCT showed that the mean residual stromal thickness at the ulcer bed was 222 ± 70 μm before surgery. The mean thickness of amniotic membrane layers at the same site was 394 ± 80 μm while the mean total corneal thickness was 623 ± 51 μm at day 1 post surgery. Thereafter a progressive reduction in thickness to 420 ± 61 μm at 6 months occurred, after which the thickness stabilized. Confocal microscopy showed that integration of the amniotic membrane tissues with corneal stroma was preceded by epithelialization over the amniotic membrane covering the ulcer. This occurred 15 ± 5 days post surgery in the successful cases. Confocal microscopy also showed that the amniotic membrane patch was degraded during the first few weeks after surgery, while the integrated amniotic tissues underwent progressive modifications characterized by early loss of amniotic epithelial cells, changes in fibrillar structure, and migration into the amniotic stroma by corneal stroma-derived cells. CONCLUSIONS Multiple layers of amniotic membrane can integrate into the corneal stroma with resulting increase in corneal thickness. This appears to be related to re-epithelialization of the transplanted membrane. Integrated amnion within the stromal defect undergoes progressive changes including contraction of tissue and repopulation by corneal stroma-derived cells.

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/mm2 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.

Descemetic and Predescemetic DALK in Keratoconus Patients: A Clinical and Confocal Perspective Study

Purpose. To evaluate the clinical outcomes and in vivo confocal microscopy (IVCM) features of keratoconus patients who underwent deep anterior lamellar keratoplasty (DALK). Methods. DALK was performed using the big bubble technique in all the patients. If the bubble was not successful to bare the descemet membrane, a manual dissection layer-by layer was performed to expose a deep stromal plane close to the DM. The patients were divided in two groups depending on the intraoperative baring of the descemet membrane: predescemetic DALK (PD-DALK) and descemetic DALK (D-DALK) group. Results. One month after surgery the D-DALK patients show an increase of mean BCVA. In the PD-DALK group mean BCVA did not show significant improvement as compared to preoperative values. At 6 months after surgery mean BCVA was found to be similar in both groups. At 1 month IVCM the peak of reflectivity of the interface was lower in D-DALK group compared to PD-DALK. At 6 months the values of reflectivity were comparable. Conclusions. At 1 month D-DALK seems to lead to a minor interface reflectivity and to a better BCVA; these differences disappear after 6 months and the values of interface reflectivity and BCVA are comparable between D-DALK and PD-DALK.

Customized Toric Intraocular Lens Implantation in Eyes with Cataract and Corneal Astigmatism after Deep Anterior Lamellar Keratoplasty: A Prospective Study

Purpose To investigate the effectiveness of toric intraocular lenses (IOLs) for treating corneal astigmatism in patients with cataract and previous deep anterior lamellar keratoplasty (DALK). Setting San Giovanni-Addolorata Hospital, Rome, Italy. Design Prospective interventional case series. Methods Patients undergoing cataract surgery after DALK for keratoconus were enrolled. Total corneal astigmatism (TCA) was assessed by a rotating Scheimpflug camera combined with Placido-disk corneal topography (Sirius; CSO, Firenze, Italy). A customized toric IOL (FIL 611 T, Soleko, Rome, Italy) was implanted in all eyes. One year postoperatively, refraction was measured, the IOL position was recorded, and vectorial and nonvectorial analyses were performed to evaluate the correction of astigmatism. Results Ten eyes of 10 patients were analyzed. The mean preoperative TCA magnitude was 4.92 ± 1.99 diopters (D), and the mean cylinder of the IOL was 6.18 ± 2.44. After surgery, the difference between the planned axis of orientation of the IOL and the observed axis was ≤10° in all eyes. The mean surgically induced corneal astigmatism was 0.35 D at 20°. The mean postoperative refractive astigmatism power was 1.13 ± 0.94 D; with respect to preoperative TCA, the reduction was statistically significant (p < 0.0001). The mean change in astigmatism power was 3.80 ± 1.60 D, corresponding to a correction of 77% of preoperative TCA power. Nine eyes out of 10 had a postoperative refractive astigmatism power ≤ 2D. Conclusions Toric IOLs can effectively correct corneal astigmatism in eyes with previous DALK. The predictability of cylinder correction is partially lowered by the variability of the surgically induced changes of TCA. This trial is registered with NCT03398109.

Epidemiology and economic impact of moderate and severe neurotrophic keratopathy in Italy

Neurotrophic keratopathy is a rare corneal disease caused by impaired corneal innervation. There is a paucity of published evidence on neurotrophic keratopathy with no published studies on the economics of neurotrophic keratopathy in the Italian or international literature. This cost analysis aimed at assessing the economic impact of moderate (persistent epithelial defect) and severe (corneal ulcer without perforation) neurotrophic keratopathy from the perspective of the National Health Service and patients in Italy. Treatment algorithm and health resource use information were collected from a panel of nine experts from Italian centres specialized in ocular/corneal conditions. National ambulatory and inpatient hospital tariffs were applied to units of service, and Agenzia Italiana del Farmaco (AIFA) published prices to pharmaceuticals. Mean annual per patient cost was derived as an average cost weighted by the proportion of patients on each respective treatment and length of the treatment. The National Health Service + patient perspective additionally included patients’ out-of-pocket expenses. The mean annual estimated National Health Service cost of treatment was €5167 (persistent epithelial defect) and €10,885 (corneal ulcer without perforation) per patient. Costs were largely driven by ambulatory visits and hospital interventions. The mean annual estimated National Health Service + patient cost was €5731 (persistent epithelial defect) and €11,478 (corneal ulcer without perforation) per patient, including cost of out-of-pocket expenses for pharmaceuticals and therapeutic contact lenses. Mean annual cost of neurotrophic keratopathy in Italy doubles with disease severity. Further research is warranted to provide more insight especially into societal costs.