Nóra Szentmáry

Elliptical nonmechanical corneal trephination: intraoperative complications and long-term outcome of 42 consecutive excimer laser penetrating keratoplasties.

Purpose: To assess intraoperative complications and long-term outcome of elliptical excimer laser trephination for penetrating keratoplasties (EELPKs) performed at the Friedrich-Alexander University of Erlangen, between 1989 and 2002. Methods: This was a retrospective, longitudinal, single-center, clinical, interventional case series. Forty-two eyes (14 Fuchs dystrophy, 11 corneal ulcer, 7 aphakic/pseudophakic bullous keratopathy, 9 corneal scars, 1 keratotorus) after EELPK were observed. Trephination was performed with a 193-nm Meditec excimer laser along metal masks with 0-8 orientation teeth/notches. Horizontal/vertical graft diameters ranged from 7.0/6.0 to 8.0/7.0 mm, and 12 to 24 interrupted sutures were used. Simultaneously, 11 eyes (26.2%) underwent cataract surgery, 3 (7.1%) underwent intraocular lens (IOL) exchange, and 1 (2.4%) underwent secondary IOL implantation. The main outcome measures included intraoperative complications, immune reactions, and final astigmatism/visual acuity at the end of follow-up. Results: During surgery, 4 (9.5%) recipients had iris bleedings, and 10 (23.8%) ring-shaped superficial corneal thermal donor damages were detected. One (2.4%) immunologic graft rejection was seen in Fuchs dystrophy, and 3 (7.1%) in corneal ulcers occurred during follow-up (4.7 ± 3.2 years). At the end of follow-up, corrected visual acuity (0.1/0.4; P < 0.001) and keratometric astigmatism (2.3 D/4.7 D, P = 0.001) increased significantly. Conclusions: In EELPK, intraoperative disadvantages, such as the need for interrupted sutures and a tendency toward higher and more irregular astigmatism, may be expected. This study does not have the power to statistically confirm the tendency of EELPK toward a lower rate of immunologic graft rejections after normal-risk keratoplasty. However, EELPK may have advantages in deep or perforated elliptically shaped corneal ulcers (such as in acanthamoeba keratitis).

Vignetting and field of view with the KAMRA corneal inlay.

Purpose. To evaluate the effect of the KAMRA corneal inlay on the retinal image brightness in the peripheral visual field. Methods. A KAMRA inlay was “implanted” into a theoretical eye model in a corneal depth of 200 microns. Corneal radius was varied to a steep, normal, and flat (7.37, 7.77, and 8.17 mm) version keeping the proportion of anterior to posterior radius constant. Pupil size was varied from 2.0 to 5.0 mm. Image brightness was determined for field angles from −70° to 70° with and without KAMRA and proportion of light attenuation was recorded. Results. In our parameter space, the attenuation in brightness ranges in between 0 and 60%. The attenuation in brightness is not affected by corneal shape. For large field angles where the incident ray bundle is passing through the peripheral cornea, brightness is not affected. For combinations of small pupil sizes (2.0 and 2.5 mm) and field angles of 20–40°, up to 60% of light may be blocked with the KAMRA. Conclusion. For combinations of pupil sizes and field angles, the attenuation of image brightness reaches levels up to 60%. Our theoretical findings have to be clinically validated with detailed investigation of this vignetting effect.

Corneal Curvature after Penetrating Keratoplasty before and after Suture Removal: A Comparison between Keratoconus and Fuchs’ Dystrophy

Purpose: To assess the differences concerning corneal curvature and visual acuity after penetrating keratoplasty (PKP) comparing keratoconus (KC) and Fuchs’ dystrophy (FUCHS). Methods: Inclusion criteria for this prospective, comparative, interventional study were: (1) one surgeon, (2) central round nonmechanical excimer laser PKP without previous surgery, (3) FUCHS (n = 35) or KC (n = 52), (4) standardized graft size (7.5–8.0 mm) and technique, 16-bite double running cross-stitch suture. In 69% of FUCHS, a triple procedure was performed. The main outcome measures were: keratometric astigmatism, surface regularity index, surface asymmetry index, keratometric central corneal power and best-corrected visual acuity before (1.2 ± 0.4 years) and after suture removal (1.8 ± 0.6 years). Results: Astigmatism did not differ significantly between KC and FUCHS (p > 0.1) before (3.3 dpt vs. 3.5 dpt median) and after suture removal (2.5 dpt vs. 3.0 dpt). Surface regularity index and surface asymmetry index were significantly higher in FUCHS than in KC (p < 0.001) at both time stages. Central power was significantly greater in KC than in FUCHS (p < 0.001) with sutures in place. Due to a significant steepening in FUCHS and flattening in KC, this difference was no longer present after suture removal. Visual acuity in KC exceeded that in FUCHS before (0.68 vs. 0.60) and even more after suture removal (0.86 vs. 0.60; p < 0.001). Conclusions: In KC, keratometric astigmatism is not higher than in FUCHS after PKP. After suture removal, graft topography in KC and FUCHS may be expected to regularize and the excessive corneal flattening in FUCHS to normalize in the mid-term.

Calculating the power of toric phakic intraocular lenses

Background and purpose:  A toric phakic intraocular lens (IOL) implanted in the anterior or posterior chamber of the eye has the potential to correct high or excessive ametropia and astigmatism with high predictability of the postoperative refraction and preservation of phakic accommodation. The calculation of spherical phakic lenses has been described previously, but a formalism for estimating the power of toric phakic lenses has not yet been published. The purpose of this study is to describe a mathematical strategy for calculating toric phakic IOLs.

Amniotic Membrane Transplantation for the Treatment of Infectious Ulcerative Keratitis Before Elective Penetrating Keratoplasty.

Purpose: Emergency keratoplasties for inflamed eyes are considered to have a worse prognosis because of immunologic graft rejection. Amniotic membranes have antiinflammatory and antiangiogenic abilities. Therefore, amniotic membrane transplantation (AMT) was performed to stabilize the situation of eyes with severe infectious keratitis before elective penetrating keratoplasty (PK). Methods: Retrospective, nonrandomized observational case series. Seven to 41 days (median, 20 days) after the onset of intensive antiinfectious medication, an AMT (6 multigrafts and 6 sandwich) was performed in 12 patients [8 men and 4 women; age 46–80 years (median, 66 years)] with herpetic (n = 5), bacterial keratitis (n = 3), or combinations (n = 4). Three to 12 months (median, 5 months) after cessation of the inflammatory status of the eye, a central elective PK (diameter, 7–8 mm) became feasible in 10 eyes. Follow-up ranged from 4 to 38 months (median, 20 months) after PK. Results: The primary success rate of AMT was 11/12 (92%). Five recurrences (41%) were treated successfully 4 times by repeat AMT (sandwich) and 1 time by emergency PK. In 2 of the 12 eyes, an irreversible endothelial immunologic graft reaction appeared 18 and 21 months after PK. One eye suffered from reversible recurrence of herpetic keratitis on the corneal graft. At the end of the follow-up, 10 of 12 grafts (83%) were clear. Conclusions: A rapid decrease in the inflammatory reaction and a fast reepithelialization because of AMT after intensive antiinfectious medication in case of severe ulcerative keratitis may help to avoid an emergency keratoplasty and improves the prognosis of the elective keratoplasty.

Interaction Between Topographic/Tomographic Parameters and Dry Eye Disease in Keratoconus Patients

Abstract Purpose: To determine the interaction between corneal topographic and tomographic parameters and dry eye syndrome (DES) in keratoconus (KC) patients. Methods: Seventy-seven eyes of 49 patients with KC (age 34.4 ± 11.6 years) were enrolled in this study. In these 77 eyes we recorded surface regularity index (SRI), surface asymmetry index (SAI) and Klyce/Maeda KC index (KCI) using the Topographic Modeling System (TMS-5, Tomey, Tennenlohe, Germany), Index of Surface Variance (ISV), Index of Vertical Asymmetry (IVA), KC Index (KI), Center KC Index (CKI), Index of Height Asymmetry (IHA) and Index of Height Decentration (IHD) using Pentacam (Pentacam HR, Oculus, Germany). Patients were subdivided into mild (grade 1–2) and severe stage (grade 3–4) KC groups according to Pentacam grading. To analyse tear film parameters we assessed in 77 KC eyes McMonnies questionnaire, Schirmer test and break-up time and in 26 eyes (10 eyes with mild KC, 16 eyes with severe KC) high-speed videokeratoscopy (during interblinking interval) using a novel commercially not available system (Tear Inspect). With Tear Inspect the analysed tear film parameters were (1) time of first irregularities of Placido rings and (2) time of eyelid closure. Patients were also subdivided into McMonnies questionnaire positive and negative groups. Results: We did not find significant difference between patients with mild and severe KC in any of the examined tear film parameters (p > 0.66). There was no significant difference in SRI, SAI, KCI, ISV, IVA, KI, CKI, IHA and IHD in McMonnies test positive and negative KC patients (p > 0.07). There was no correlation between SRI, SAI, KCI, ISV, IVA, KI, CKI, IHA and IHD and any of the examined tear film parameters (without high-speed videokeratoscopy) neither in 77 KC patients nor in mild or severe KC eyes (r < 0.3). Conclusions: There is no interaction between DES and topographic/tomographic changes in KC-patients.

Magnification and accommodation with phakic intraocular lenses

Background and Purpose:  The calculation of phakic lenses (PL) was described by van der Heijde et al. [Klin. Monatsbl. Augenheilkd (1988) Vol. 193, pp. 99–102] , but a formalism for estimating relative magnification compared with spectacle correction and accommodation effects are not yet published. The purpose of this study was to describe a mathematical strategy for calculating PL and relative magnification as a function of object vergence (phakic accommodation).

Impact of crosslinking/riboflavin-UVA-photodynamic inactivation on viability, apoptosis and activation of human keratocytes in vitro

Abstract Riboflavin-UVA photodynamic inactivation is a potential treatment alternative in therapy resistant infectious keratitis. The purpose of our study was to determine the impact of riboflavin-UVA photodynamic inactivation on viability, apoptosis and activation of human keratocytes in vitro. Primary human keratocytes were isolated from human corneal buttons and cultured in DMEM/Hams F12 medium supplemented with 10% fetal calf serum. Keratocytes underwent UVA light illumination (375 nm) for 4.10 minutes (2 J/cm2) during exposure to different concentrations of riboflavin. Twenty-four hours after treatment, cell viability was evaluated photometrically, whereas apoptosis, CD34 and alpha-smooth muscle actin (α-SMA) expression were assessed using flow cytometry. We did not detect significant changes in cell viability, apoptosis, CD34 and α-SMA expression in groups only treated with riboflavin or UVA light. In the group treated with riboflavin-UVA-photodynamic inactivation, viability of keratocytes decreased significantly at 0.1% riboflavin (P<0.01) while the percentage of CD34 (P<0.01 for both 0.05% and 0.1% riboflavin) and alpha-SMA positive keratocytes (P<0.01 and P<0.05 for 0.05% and 0.1% riboflavin, respectively) increased significantly compared to the controls. There was no significant change in the percentage of apoptotic keratocytes compared to controls at any of the used riboflavin concentrations (P = 0.09 and P = 0.13). We concluded that riboflavin-UVA-photodynamic-inactivation decreases viability of myofibroblastic transformation and multipotent haematopoietic stem cell transformation; however, it does not have an impact on apoptosis of human keratocytes in vitro.

Viability, Apoptosis, Proliferation, Activation, and Cytokine Secretion of Human Keratoconus Keratocytes after Cross-Linking

Purpose. The purpose of this study was to determine the impact of cross-linking (CXL) on viability, apoptosis, proliferation, activation, and cytokine secretion of human keratoconus (KC) keratocytes, in vitro. Methods. Primary KC keratocytes were cultured in DMEM/Hams F12 medium supplemented with 10% FCS and underwent UVA illumination (370 nm, 2 J/cm2) during exposure to 0.1% riboflavin and 20% Dextran in PBS. Twenty-four hours after CXL, viability was assessed using Alamar blue assay; apoptosis using APO-DIRECT Kit; proliferation using ELISA-BrdU kit; and CD34 and alpha-smooth muscle actin (α-SMA) expression using flow cytometry. Five and 24 hours after CXL, FGFb, HGF, TGFβ1, VEGF, KGF, IL-1β, IL-6, and IL-8 secretion was measured using enzyme-linked-immunoabsorbent assay (ELISA). Results. Following CXL, cell viability and proliferation decreased (P < 0.05; P = 0.009), the percentage of apoptotic keratocytes increased (P < 0.05) significantly, and CD34 and α-SMA expression remained unchanged (P > 0.06). Five hours after CXL, FGFb secretion increased significantly (P = 0.037); however no other cytokine secretion differed significantly from controls after 5 or 24 hours (P > 0.12). Conclusions. Cross-linking decreases viability, triggers apoptosis, and inhibits proliferation, without an impact on multipotent hematopoietic stem cell transformation and myofibroblastic transformation of KC keratocytes. CXL triggers FGFb secretion of KC keratocytes transiently (5 hours), normalizing after 24 hours.

Hornhautbrechwert nach ‚Descemet Stripping Automated Endothelial Keratoplasty‘ (DSAEK) – Modellierung und Konzept für die Berechnung von Intraokularlinsen

BACKGROUND AND PURPOSE Descemet stripping automated endothelial keratoplasty (DSAEK) is an established treatment option for pathologies of the corneal endothelium. It is typically accompanied with a hyperopic shift in refraction. The purpose of this work is to predict corneal geometry after DSAEK based on model data and to present a concept how to determine corneal power, e.g. for intraocular power calculation to prevent a refractive surprise with a subsequent cataract surgery. MATERIAL AND METHODS Based on data of the Kooijman schematic model eye we simulated a microkeratome cut parallel to the corneal front surface for donor trephination to determine the radial thickness profile of the posterior corneal donor lamella. This donor lamella was tension-neutrally adapted to the back surface of the host and the profile of the cornea after DSAEK was derived and characterized by a quadric surface. Comparison with the curvature of the host without and with donor could resample hyperopic shift which was published in literature. A method was shown how to determine corneal power after DSAEK. RESULTS From the data of the Kooijman schematic model eye and the donor characteristics central / peripheral corneal thickness was increased by 150 / 250μm due to adaptation of the donor lamella. Geometry of corneal back surface showed a reduced radius of curvature (by about 0.9mm) and a change in conic constant (by about -0.13). Persistent clinically observed hyperopic shift correlates to the change in geometry of the cornea due to adaptation of the donor lamella, which reduces corneal power by 0.88 D. CONCLUSION DSAEK leads to a hyperopic shift in refraction, which can be explained by a change in corneal back surface geometry. In case of subsequent cataract surgery, the intraocular lens power should be calculated with consideration of both corneal surfaces rather than keratometry or corneal topography in order to minimize a systematic hyperopic shift due to misinterpretation of corneal power after DSAEK. In case of a Triple-DSAEK, a target refraction of -1.5 D should be chosen in order to safely prevent postoperative hyperopia.