Roberta Calienno

Femtosecond Laser Arcuate Keratotomy for the Correction of High Astigmatism after Keratoplasty

PURPOSE To determine the feasibility and initial outcomes of using a femtosecond laser to perform arcuate keratotomies to correct high post-keratoplasty astigmatism. DESIGN Prospective noncomparative interventional case series. PARTICIPANTS Twelve eyes of 12 consecutive patients (mean age 44.9+/-9.5 years) who presented with a high degree of astigmatism, noncorrectable with spectacles or contact lenses (10 post-penetrating keratoplasty, 2 post-deep lamellar keratoplasty), and were candidates for relaxing incisional corneal surgery. METHODS The Femtec (20/10 Perfect Vision, GmbH, Heidelberg, Germany) femtosecond laser performed paired 90-degree angled arcuate incisions on the graft button. The incision sites and depths were programmed at 1.00 mm inside the graft edge and at 90% of the corresponding local graft thickness, whereas the angular lengths of the cuts were determined by analyzing the locations and extents of the steepest meridians in the topographic map. MAIN OUTCOME MEASURES Changes in uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), mean subjective and topographically determined astigmatism; imaging of incisions by anterior segment optical coherence tomography (AS-OCT); and wound healing by in vivo confocal microscopy (IVCM). RESULTS Postoperative follow-up extended to 6 months. Mean uncorrected logarithm of the minimum angle of resolution (logMAR) BSCVA and UCVA improved from preoperative values of 0.25+/-0.16 and 1.05+/-0.18 to 6-month values of 0.11+/-0.12 (standard deviation) and 0.55+/-0.34, respectively (P<0.05). Mean subjective astigmatism was 7.16+/-3.07 diopters (D) preoperatively and 2.23+/-1.55 D at 1 month after surgery (P = 0.002) and remained stable to the end of follow-up. Anterior segment optical coherence tomography image analysis showed that the depth and location of the incisions were consistent with the preoperative surgical plan. In vivo confocal microscopy showed mild edema and keratocyte activation along the incision edges, together with initial epithelial ingrowth inside the wound, followed by subsequent moderate fibrotic scarring. CONCLUSIONS Arcuate keratotomies performed with the femtosecond laser were effective in reducing post-keratoplasty astigmatism. Laser-generated incisions within the graft button presented precise geometry and reliable depth of incision, with a wound healing pattern characterized by epithelial ingrowth and mild fibrosis. FINANCIAL DISCLOSURE(S) The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Corneal cross-linking: intrastromal riboflavin concentration in iontophoresis-assisted imbibition versus traditional and transepithelial techniques.

PURPOSE To determine differences in riboflavin concentration in the anterior, intermediate, and posterior stroma after 3 corneal cross-linking imbibition techniques (standard epithelial [epi]-off, epi-on, and iontophoresis-assisted administration) of 0.1% riboflavin. DESIGN Experimental laboratory investigation of human cadaver corneas not suitable for transplantation. METHODS Ten corneas underwent imbibition with epi-on (n = 3), epi-off (n = 3), iontophoresis (n = 3), and saline exposure (control; n = 1). Femtosecond laser was used to produce 3 8-mm discs of the superficial (0-150 μm), intermediate (150-300 μm), and deep stroma (>300 μm). Riboflavin concentration was measured with high-performance liquid chromatography. The main outcome measure was riboflavin concentration at the 3 evaluated depths. RESULTS The overall stromal concentration of riboflavin was 34.1 ± 7.1 μg/g in epi-off, 7.2 ± 3.7 μg/g in epi-on, and 15.0 ± 5.1 μg/g in iontophoresis. The mean riboflavin content in the superficial slice in the epi-off group was about 2-fold greater than that of the iontophoresis group (50.5 ± 5.3 μg/g and 23.6 ± 2.5 μg/g, respectively) and 4-fold greater than that of the epi-on group (11.7 ± 3.3 μg/g). Similar differences among the 3 groups were observed for the intermediate and posterior stromal slices, presenting an evident reduction of riboflavin concentration with increasing depth in all groups. Slice depth-dependent decrease in riboflavin concentration was statistically significant (general linear model (GLM); F1,6 = 62.265, P < .001), as was the group-dependent variation (GLM; F2,6 = 20.268, P = .002) and the slice depth group interaction (GLM; F2,6 = 18.004, P = .002). CONCLUSIONS Corneal cross-linking transepithelial iontophoresis imbibition yielded greater and deeper riboflavin saturation with respect to conventional epi-on, while maintaining the advantages of avoiding epithelial removal and shorter procedure time, but did not reach concentrations obtained with standard epi-off.

An in vivo confocal microscopy and impression cytology analysis of preserved and unpreserved levobunolol-induced conjunctival changes.

Purpose To provide an in vivo confocal microscopy (IVCM) and impression cytology analysis of preserved- and unpreserved levobunolol-induced changes of conjunctival epithelium. Methods 27 eyes of 27 patients were consecutively randomized to receive preserved or unpreserved levobunolol; all patients had a recent diagnosis of primary open angle glaucoma (POAG) or ocular hypertension and were not previously treated with topical medications. IVCM and impression cytology were performed before and after six months of therapy. Goblet cells density and a conjunctival epithelium regularity index were considered in the IVCM analysis, whereas impression cytology specimens were graded and scored in accordance with Nelsons method. Results After six months of therapy, IVCM and impression cytology parameters showed significant differences with respect to baseline in both groups (p<0.001); significant differences were also found between the two groups (p<0.001). The IVCM analysis showed a goblet cells density reduction (61% and 17% from baseline, respectively in group 1 and 2) (p<0.001) and an higher index of epithelial regularity (p<0.001) in both groups; the impression cytology analysis showed an higher score in both groups (p<0.001). Conclusions All the IVCM and impression cytology parameters correlated well with the conjunctival modifications induced by the topical therapy, suggesting the less toxicity of unpreserved drugs

Morphological modification of the cornea after standard and transepithelial corneal cross-linking as imaged by anterior segment optical coherence tomography and laser scanning in vivo confocal microscopy.

Purpose: In vivo analysis of corneal modifications after traditional and transepithelial corneal cross-linking (CXL). Methods: Forty eyes of 35 patients underwent traditional or transepithelial CXL; there was randomization of 20 eyes to each group. By means of in vivo confocal microscopy and anterior segment ocular coherence tomography, we evaluated corneal alterations at 1 week, 1 month, and 3, 6, and 12 months after the treatment. Results: During follow-up, in vivo confocal microscopy showed a significant decrease in anterior keratocyte density (P = 0.001) and more evident stromal edema and keratocyte activation (P = 0.001) in the traditional group, whereas in the transepithelial group, no significant changes were observed (P > 0.05). Anterior segment ocular coherence tomography indicated the presence of hyperreflective stromal line significantly deeper and more persistent in the traditional group (P < 0.001). Conclusions: The preliminary results suggest that traditional CXL induced marked corneal modifications, which were poorly evident in the transepithelial group.

Structural modifications and tissue response after standard epi-off and iontophoretic corneal crosslinking with different irradiation procedures.

PURPOSE The aim of this study is to investigate modifications in human cadaver corneas after different crosslinking procedures, including standard epi-off treatment, iontophoresis imbibition, and different exposure to ultraviolet A (UVA) sources (30 minutes at 3 mW and 9 minutes at 10 mW). METHODS A total of 12 human cadaver corneas was examined and divided as follows: 3 served as control (group 1), 3 were treated with a standard epi-off procedure (group 2), 6 underwent iontophoresis imbibition for 5 minutes, and then 3 were irradiated for 30 minutes with 3 mW UVA (group 3), and 3 for 9 minutes at 10 mW UVA (group 4). Deformation amplitude index was measured before and after the corneas underwent treatment. After treatment, corneas were prepared for hematoxylin-eosin and immunohistochemistry evaluation. The expression of TUNEL, matrix metalloproteinase-1 (MMP-1), collagen type I, and CD34 was investigate in all samples. RESULTS The deformation amplitude index decreased in all groups, in particular in group 4, indicating an improvement of corneal biomechanical properties. Immunohistochemical staining showed a significant stromal alteration in group 2, mild damage in group 3, and no modifications in corneal morphology in group 4. The TUNEL (P < 0.001) and MMP-1 (P = 0.002) positivity was more evident in group 4. Collagen type I positivity significantly increased in groups 3 (P = 0.002) and 4 (P = 0.002). The CD34 expression was more evident in groups 2 (P = 0.003) and 3 (P = 0.003). CONCLUSIONS Iontophoresis imbibition followed by UVA irradiation for 9 minutes at 10 mW determined less tissue damage and better stromal remodeling.

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 Corneal Biomechanical Properties Modification after Small Incision Lenticule Extraction Using Scheimpflug-Based Noncontact Tonometer

Purpose. To quantify the effect of small incision lenticule extraction (SMILE) on the corneal biomechanics using Scheimpflug noncontact tonometer (Corvis ST). Methods. Twenty eyes of twenty patients, evaluated as eligible for surgery, with high myopia and/or moderate myopic astigmatism, underwent small incision lenticule extraction (SMILE). All patients underwent Corvis ST preoperatively and postoperatively after 1 week, and 1 and 3 months to observe alterations of corneal biomechanical properties. The main outcome measures were Deformation Amplitude, 1st-AT, and 2nd-AT. The relationship between the amount of stroma removed and the percentage variation of the measured parameters from baseline was evaluated with generalized linear model from each time point. For completeness also intraocular pressure (IOP), central corneal thickness (CCT), and their variations after surgery were evaluated. Results. The ratio between the amount of removed refractive error and, respectively, changes of Deformation Amplitude, 1st-AT, and 2nd-AT were significantly modified at the 1st week after surgery (P = 0.005; P = 0.001; P = 0.024). At 1 and 3 months these values did not show statistically significant alterations. Intraocular pressure and central corneal thickness showed statistically significant changes during follow-up. Conclusions. No significant modifications in biomechanical properties were observed after SMILE so this procedure could induce only minimal transient alterations of corneal biomechanics.

The effect of standard and transepithelial ultraviolet collagen cross-linking on human corneal nerves: an ex vivo study.

PURPOSE To evaluate the early effect of standard and transepithelial collagen cross-linking on human corneal nerves in donor eyes by ex vivo confocal microscopy and acetylcholinesterase staining. DESIGN Experimental laboratory investigation. METHODS Eight human eye bank corneal buttons (mean age, 73.6 years) were included. Ultraviolet A collagen cross-linking was performed postmortem on 3 corneas with the standard protocol involving epithelial debridement and 4 corneas by the transepithelial approach. One cornea served as a control. Corneal nerves were evaluated using confocal microscopy and acetylcholinesterase histology. RESULTS Confocal microscopy demonstrated the absence of subbasal nerves in corneas treated by the standard technique. These nerves were preserved in corneas treated by the transepithelial approach. Stromal nerves were visible in both groups. Histology of corneas treated by the standard technique revealed localized swellings of the stromal nerves with disruption of axonal membrane and loss of axonal continuity within the treatment zone. These changes were absent in corneas treated by the transepithelial approach. CONCLUSIONS This study highlights the immediate effects of collagen cross-linking on the corneal nerves in an ex vivo model. The absence of subbasal nerves in the early phase of treatment appears to be attributable mainly to mechanical removal of epithelium, rather than ultraviolet light-induced damage. Localized swelling of the stromal nerves was the main difference between the 2 treatment protocols. Further research on laboratory animals would be necessary to verify these changes over a specified time course without the super-addition of postmortem changes.

Big bubble deep anterior lamellar keratoplasty: the collagen layer in the wall of the big bubble is unique

In big bubble (BB), deep anterior lamellar keratoplasty intracorneal injection of air separates Descemets membrane (DM) and the pre‐Descemets layer (Duas layer [DL]) to create a type 1 BB. We tested the hypothesis that air injection after excision or ablation of DL will fail to produce a BB.

Induced Inflammation and Apoptosis in Femtosecond Laser-Assisted Capsulotomies and Manual Capsulorhexes: An Immunohistochemical Study

PURPOSE To evaluate cellular inflammation and apoptosis induced in the central portion of capsulorhexes/capsulotomies during cataract surgery, comparing a conventional manual technique and a femtosecond laser-assisted procedure at different energy settings using two laser systems. METHODS Fifty-six capsulorhexes/capsulotomies were divided into four groups: the manual group (14 capsulorhexes) performed with the manual technique; the 7.0-µJ group (14 capsulotomies) (LensAR laser system; Lensar, Inc., Orlando, FL); the 10-µJ group (14 capsulotomies) (LenSx laser system; Alcon Laboratories, Inc., Fort Worth, TX); and the 13.0-µJ group (14 capsulotomies) (LenSx laser system). All samples were stained for cellular apoptosis analysis (TUNEL assay) and cellular induced inflammation (NF-κB). RESULTS One-way analysis of variance indicated a statistically significant difference in the percentage of NF-κB and TUNEL positive cells between the four groups, (F [3.52] = 14.717, P < .001) and (F [3.52] = 139.561, P < .001), respectively. Post-hoc analysis indicated a statistically significant difference in the percentage of NF-κB positive cells between the 13.0-µJ group and the manual, 7.0-µJ, and 10-µJ groups (P < .001, = .037, and < .001, respectively). Post-hoc analysis of differences in TUNEL positive cells indicated a significant difference between the 7.0-µJ and 10-µJ groups (P <.017) and between the 13.0-µJ group and the manual, 7.0-µJ, and 10-µJ groups (P < .001, < .001, and < .001, respectively). CONCLUSION The results show a higher percentage of NF-κB and TUNEL positive cells in the 13.0-µJ group compared to the 7.0-µJ, 10-µJ, and manual groups. Therefore, inflammatory response and cell death increased at increasing energies. An effective capsulotomy in femtosecond laser-assisted cataract surgery with minimal detrimental apoptotic and inflammatory effects is possible if the laser system is set to use the minimum energy level.