Annalisa Canovetti

Morphologic study of the cornea by in vivo confocal microscopy and optical coherence tomography after bifocal refractive corneal inlay implantation

Purpose To evaluate the biocompatibility of the Flexivue Microlens intracorneal inlay based on healing of corneal wounds and analysis of corneal structural features using in vivo confocal microscopy (IVCM) and anterior segment optical coherence tomography (AS‐OCT). Setting Ophthalmology Department, Misericordia e Dolce Hospital, Prato, Italy. Design Case series. Methods The intracorneal inlay was inserted in a stromal pocket created in the nondominant eye of emmetropic presbyopic patients using a femtosecond laser. In vivo confocal microscopy and AS‐OCT examinations were performed preoperatively and 1, 6, and 12 months postoperatively. Results The mean follow‐up was 7.6 months. In the early postoperative period, IVCM showed intense cellular activity in the stroma around the inlay, edema, inflammation, and degenerative material deposition but normal regularity after 12 months. Anterior segment OCT showed a regular planar shape of the corneal pocket in all eyes. The mean of the side‐cut angles was 30.7 degrees. The mean difference between the measured and planned pocket depth was 9.77 &mgr;m. At 1 month, hyperreflective areas beneath the inlay and microfolds were observed in 21 of the 52 eyes. After 12 months, the anterior segment profile was regular and interface pocket reflectivity decreased over time. Six patients had inlay removal postoperatively (3 before 6 months; 3 before 12 months); after removal, IVCM and AS‐OCT showed clear corneas without signs of irregularity. Conclusion In vivo confocal microscopy and AS‐OCT analysis showed that the inlay elicited a low‐level wound‐healing response in its immediate vicinity with no alteration in the corneal structures. Financial Disclosure Dr. M. Fantozzi is a member of the Presbia medical advisory board. No other author has a financial or proprietary interest in any material or method mentioned.

Laser-Assisted Penetrating Keratoplasty: 1-Year Results in Patients Using a Laser-Welded Anvil-Profiled Graft

PURPOSE To describe a new laser-assisted penetrating keratoplasty technique combining a femtosecond anvil-like trephination pattern with the laser welding procedure. DESIGN Cohort prospective study with 1 year of follow-up (June 2011 through January 2013). METHODS This study was performed at Misericordia e Dolce Public Hospital, Prato, Italy. Twenty-four eyes of 22 patients underwent penetrating keratoplasty: 4 had granular dystrophy, 12 had keratoconus in its final stages, 3 had post-herpetic leukoma, and 5 had corneal scars. A femtosecond laser was used to create anvil-profiled cuts in donor and recipient corneas. Diode laser welding was performed, supporting standard suturing. All patients were evaluated for corrected distance visual acuity, pachymetry, manifest astigmatism, and endothelial cell density after 1, 3, 6, and 12 months. RESULTS Mean ± standard deviation postoperative corrected visual acuity was 0.48 ± 0.23 logarithm of the minimal angle of resolution (logMAR), 0.30 ± 0.18 logMAR, 0.18 ± 0.13 logMAR, and 0.13 ± 0.16 logMAR at 1, 3, 6, and 12 months, respectively. At the same follow-up times, mean pachymetry was 537 ± 57 μm, 533 ± 74 μm, 528 ± 72 μm, and 529 ± 58 μm, respectively; and mean endothelial cell density was 1945 ± 371 cells/mm(2), 1881 ± 410 cells/mm(2), 1781 ± 401 cells/mm(2), and 1730 ± 376 cells/mm(2), respectively. Mean manifest and topographic postoperative astigmatism were: 3.6 ± 2.5 diopters (D) and 4.65 ± 2.57 D at 1 month, 2.93 ± 2.34 D and 4.79 ± 2.85 D at 3 months, 2.82 ± 1.75 D and 3.44 ± 2.28 D at 6 months, and 2.08 ± 1.25 D and 2.73 ± 2.01 D at 12 months, respectively. All surgical operations were successful and without intraoperative complications. CONCLUSIONS The use of the anvil trephination profile was effective for performing laser-assisted penetrating keratoplasty. The large donor-recipient interface enables the laser welding procedure and good preservation of the recipients endothelial cell pool.

The 'anvil' profile in femtosecond laser-assisted penetrating keratoplasty.

Editor, T he introduction of the femtosecond (FS) laser technology in the surgery room has allowed great advances in the field of corneal surgery and in particular in penetrating keratoplasty (PK). The FS laser enables to design vertical and lamellar intrastromal incisions with a variety of shapes and angulations at a precise depth, with minimal collateral tissue injury (Yoo & Hurmeric 2011). Various incision patterns for the creation of a particular flap shape in PK have been described, to have a watertight closuring effect of the surgical wound, to prepare a biomechanically stable flap and to improve the healing process (Bahar et al. 2008; Yoo & Hurmeric 2011; Maier et al. 2012). An optimised wound shape maximises the surface area of the wound incision and improve fit and stability of the graft–host junction. In this letter, we describe a new anvil-shaped laser incision used in PK. This design has the purpose to create a more structurally stable and predictable wound configuration with the aim of a faster recovery of vision and higher optical quality compared with the conventional blade trephination and the most common laser-cut patterns. The ‘anvil’ profile is designed as described in the following (Fig. 1). Donor and recipient corneal trephination are performed using a 150 kHz FS laser (iFS150 , Intralase FS Laser; Abbott Medical Optics – AMO, Santa Ana, CA, USA). As concerned iFS150 settings, we refer to the following technical parameters for the donor trephination:

Aceclidine, brimonidine tartrate, and dapiprazole: Comparison of miotic effect and tolerability under different lighting conditions

PURPOSE: To evaluate the effect of 3 types of topically applied miotic eyedrops on the pupil diameter in normal eyes. SETTING: Department of Neurosciences, Section of Ophthalmology, University of Pisa, Pisa, Italy. METHODS: This prospective study comprised 60 eyes of 30 healthy volunteers treated with aceclidine 0.02%, brimonidine tartrate 0.20%, and dapiprazole 0.25%. Pupil diameter was measured under scotopic, mesopic (4 lux), and photopic (50 lux) conditions using an infrared pupillometer incorporated into a CSO topographer. The first measurement was obtained before single instillation of 1 type of miotic eyedrop. Subsequent measurements were taken after 30, 120, and 240 minutes. Each additional medication was tested after an interval of at least 6 weeks to avoid possible effects from the previously administered drug. All patients received a questionnaire and were asked to grade the tolerability of each eyedrop using a subjective scoring system. RESULTS: Aceclidine 0.02% had no significant miotic effect. Brimonidine tartrate 0.20% caused significant miosis within 30 minutes and 120 minutes; after 240 minutes, the effect under all luminance conditions decreased to baseline levels without reaching the initial level. Dapiprazole 0.25% had a miotic effect similar to that of brimonidine but produced many side effects including hyperemia and burning, which many patients said caused significant discomfort. CONCLUSIONS: Brimonidine tartrate 0.20% had the best miotic effect of the 3 agents tested and was well tolerated by the patients. The reproducible miotic effect of brimonidine tartrate under all lighting conditions might benefit postoperative refractive patients who report night‐vision difficulties related to large pupils.

Laser welding in penetrating keratoplasty and cataract surgery of pediatric patients: early results

Diode laser welding of ocular tissues is a procedure that enables minimally invasive closure of a corneal wound. This procedure is based on a photothermal effect: a water solution of Indocyanine Green (ICG) is inserted in the surgical wound, in order to stain the corneal tissue walls. The stained tissue is then irradiated with a low power infrared diode laser, delivering laser light through a 300-μm core diameter optical fiber. This procedure enables an immediate closure of the wounds: it is thus possible to reduce or to substitute the use of surgical threads. This is of particular interest in children, because the immediate closure improves refractive outcome and anti-amblyopic effect; moreover this procedure avoids several general anaesthesia for suture management. In this work, we present the first use of diode laser welding procedure in paediatric patients. 5 selected patients underwent cataract surgery (Group 1), while 4 underwent fs-laserassisted penetrating keratoplasty (Group 2). In Group 1 the conventional surgery procedure was performed, while no stitches were used for the closure of the surgical wounds: these were laser welded and immediately closed. In Group 2 the donor button was sutured upon the recipient by 8 single stitches, instead of 16 single stitches or a running suture. The laser welding procedure was performed in order to join the donor tissue to the recipient bed. Objective observations in the follow up study evidenced a perfect adhesion of the laser welded tissues, no collateral effects and an optimal restoration of the treated tissues.

The Use of Femtosecond Laser and Corneal Welding in the Surgery of Keratoconus

The laser-assisted lamellar and penetrating keratoplasty, supported by the use of laser welding procedure, is particularly suitable for keratoconus patients. Laser welding approach is based on the use of a near infrared laser that induces a photothermal effect mediated by a biocompatible chromophore (Indocyanine Green).

Deep stroma investigation by confocal microscopy

Laser assisted keratoplasty is nowadays largely used to perform minimally invasive surgery and partial thickness keratoplasty [1-3]. The use of the femtosecond laser enables to perform a customized surgery, solving the specific problem of the single patient, designing new graft profiles and partial thickness keratoplasty (PTK). The common characteristics of the PTKs and that make them eligible respect to the standard penetrating keratoplasty, are: the preservation of eyeball integrity, a reduced risk of graft rejection, a controlled postoperative astigmatism. On the other hand, the optimal surgical results after these PTKs are related to a correct comprehension of the deep stroma layers morphology, which can help in the identification of the correct cleavage plane during surgeries. In the last years some studies were published, giving new insights about the posterior stroma morphology in adult subjects [4,5]. In this work we present a study performed on two groups of tissues: one group is from 20 adult subjects aged 59 ± 18 y.o., and the other group is from 15 young subjects, aged 12±5 y.o.. The samples were from tissues not suitable for transplant in patients. Confocal microscopy and Environmental Scanning Electron Microscopy (ESEM) were used for the analysis of the deep stroma. The preliminary results of this analysis show the main differences in between young and adult tissues, enabling to improve the knowledge of the morphology and of the biomechanical properties of human cornea, in order to improve the surgical results in partial thickness keratoplasty.

Femtosecond laser assisted design of sutureless intrastromal graft as an alternative to partial thickness keratoplasty

Minimally invasive laser assisted surgery in ophthalmology is continuously developing in order to find new surgical approaches, preserve patient tissue and improve surgical results in terms of cut precision, restoration of visual acuity, and invasiveness. In order to achieve these goals, the current approach in corneal transplant is lamellar keratoplasty, where only the anterior or posterior part of the patient’s cornea is substituted depending on the lesion or pathology. In this work, we present a novel alternative approach: a case study of intrastromal sutureless transplant, where a portion of the anterior stroma of a donor cornea was inserted into the stroma of the recipient cornea, aiming to restore the correct thickness of the patient’s cornea. The patient cornea was paracentrally thin, as the result of a trophic ulcer due to ocular pemphigoid. A discoid corneal graft from the anterior stroma of a donor eye was prepared: a femtosecond laser cut with a trapezoidal profile (thickness was 300 μm, minor and major basis were 3.00 and 3.50 mm, respectively). In the recipient eye, an intrastromal cut was also performed with the femtosecond laser using a specifically designed mask; the cut position was 275 μm in depth. The graft was loaded into an injector and inserted as an intrastromal presbyopic implant. The postoperative analysis evidenced a clear and stable graft that selectively restored corneal thickness in the thinned area. Intrastromal corneal transplant surgery is a minimally invasive alternative to anterior or posterior lamellar keratoplasty in select cases. We believe that Sutureless Intrastromal Laser Keratoplasty (SILK) could open up new avenues in the field of corneal transplantation by fully utilizing the potential and precision of existing lasers.

Improving Boston type 1 keratoprosthesis procedure: one-touch femtosecond-assisted preparation and centration of donor carrier tissue.

Purpose: We describe a technique to avoid decentration of the visual axis of the Boston type 1 keratoprosthesis (Kpro), performing 2 concentric trephinations with femtosecond laser. Methods: Two concentric side cuts were performed in a donor cornea using the 150-kHz Intralase™ FS laser. Within the same applanation procedure, an 8.5-mm-diameter anterior side cut was performed, followed by a concentric 3-mm-diameter anterior side cut. Results: The technique was successfully replicated in 7 cases. Conclusions: Femtosecond laser-assisted double trephination results in a correctly prepared donor cornea, and in an inner side precisely matched with the prosthesis. At the end of the surgery, the Kpro was correctly centered.