Daisuke Tomida

The Contribution of the Posterior Surface to the Corneal Aberrations in Eyes after Keratoplasty

PURPOSE To investigate the contribution of posterior corneal surfaces to higher-order aberrations (HOAs) of the cornea, optical quality, and visual acuity after keratoplasty. METHODS Corneal topography of anterior and posterior surfaces and pachymetry were conducted using anterior segment optical coherence tomography (AS-OCT) in 40 eyes (10 eyes after penetrating keratoplasty [PK], 10 eyes after deep anterior lamellar keratoplasty [DALK], 10 eyes after Descemets stripping automated endothelial keratoplasty [DSAEK], and 10 normal eyes). Anterior, posterior, and total corneal HOAs were calculated using ray-tracing and decomposition into Zernike polynomials and were evaluated as root mean square values. Modulation transfer functions (MTFs) were also evaluated. RESULTS Topography maps of the anterior and posterior surfaces showed reverse patterns in the normal, PK, and DALK eyes, but not in DSAEK eyes. In the normal, PK, and DALK eyes, the total corneal HOAs were significantly smaller (~10%) than were the HOAs of the anterior surface (P < 0.01), whereas there was no significant difference between total and anterior HOAs in the DSAEK eyes (P = 0.483). In the normal, PK, and DALK eyes, the MTFs of the total cornea were slightly better than those of the anterior surface. In the DSAEK eyes, the MTFs of the total cornea were lower than those of the anterior surface. Visual acuity was significantly correlated with total and anterior surface HOAs (P < 0.05). CONCLUSIONS Posterior surfaces compensate for anterior aberrations in normal, PK, and DALK eyes. In DSAEK eyes, the posterior surface increased total corneal HOAs and had a negative influence on MTFs.

C9-R95X Polymorphism in Patients with Neovascular Age-Related Macular Degeneration

PURPOSE A non-sense mutation at codon 95 in the gene encoding complement factor C9 (C9-R95X) is found most frequently among Japanese. The authors investigated the association between C9-R95X and Japanese patients with neovascular age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV). METHODS The presence of the C9-R95X polymorphism was assessed by direct sequencing in Japanese patients with either PCV (n = 105) or neovascular AMD (n = 198) and 396 control subjects. Multivariate regression analyses were conducted. Photocoagulation was applied in the eyes of mice with a heterozygous defect in the C3 gene and control wild-type mice. Photocoagulation was also applied to wild-type mice before either anti-C9 antibody or isotype IgG was injected into the eyes. The eyes were collected later for measurement of vascular endothelial growth factor (VEGF) and histological evaluation of choroidal neovascularization (CNV). RESULTS The frequency of those with one or two C9-R95X variants was lower in neovascular AMD (2.02%) than in PCV (5.71%) and controls (6.05%). The presence of C9-R95X conferred a 4.7-fold reduction (95% confidence interval, 1.2-18.1; P = 0.021) in the risk for neovascular AMD after adjusting for the major AMD risk factors. A heterozygous defect in the C3 gene was associated with the reduced growth of laser-induced CNV, as was intraocular injection of anti-C9 antibody. This reduced CNV growth was accompanied by a decreased level of secreted VEGF in the intraocular fluid. CONCLUSIONS These findings support the notion that the haploinsufficiency of C9, a terminal complement complex component, engenders reduced intraocular secretion of VEGF and decreased risk for CNV development.

Suppression of Choroidal Neovascularization and Quantitative and Qualitative Inhibition of VEGF and CCL2 by Heparin

PURPOSE To study the effect of heparin on the development of laser-induced choroidal neovascularization (CNV) and to assess the underlying molecular mechanisms. METHODS Bone marrow transplantation (BMT) was conducted by intravenous injection of green fluorescence protein (GFP)-labeled bone marrow cells (1 × 10(7) cells) into irradiated (9 Gy) C57BL/6J mice. Laser photocoagulation was applied to induce CNV; subsequently, unfractionated heparin or phosphate-buffered saline was injected into mice that did or did not undergo BMT. The area of CNV, distribution of injected heparin, and quantities of infiltrating cells positive for Griffonia simplicifolia (GS) and GFP inside and outside the CNV were evaluated. Effects of heparin on the secretion of VEGF, CCL2, and TNF-α by ARPE19 cells and on the binding of VEGF, CCL2, TNF-α, and their receptors were analyzed in vitro. RESULTS Intravitreal injection of heparin at higher doses reduced the size of the CNV. Heparin localized at the vascular structures and photoreceptor layers adjacent to the laser scar. Only GS-positive cells infiltrating outside the CNV were reduced significantly, but not those inside the CNV or those expressing GFP. Relative decreases in VEGF and CCL2 levels were observed in media of ARPE19 cells at higher heparin concentrations. In vitro binding assays revealed that heparin and porcine ocular fluid, respectively, suppressed the binding of VEGF to VEGFR2 and CCL2 to CCR2. CONCLUSIONS Intravitreal heparin injection inhibited CNV development. Reduced VEGF and CCL2 secretion by RPE cells and suppression of VEGF-VEGFR2 and CCL2-CCR2 interactions at the laser site mediated by heparin may contribute to the pharmacologic effect.

Aetiology-specific comparison of long-term outcome of deep anterior lamellar keratoplasty for corneal diseases

Aims To evaluate the long-term outcome of deep anterior lamellar keratoplasty (DALK) for the treatment of herpetic keratitis, keratoconus, stromal scars and corneal dystrophies. Methods This retrospective consecutive case study includes 275 consecutive eyes of 254 patients who underwent DALK; 35 eyes with herpetic keratitis, 114 eyes with stromal scar, 93 eyes with keratoconus and 67 eyes with corneal dystrophy. Exclusion criteria included therapeutic DALK for the treatment of descemetocele or infectious keratitis, and eyes with limbal stem cell deficiency. Patients were examined at 1, 3 and 6 months, and 1, 3 and 5 years after DALK. Graft survival rate, best corrected visual acuity (BCVA), endothelial cell density (ECD) and postoperative complications were evaluated. Results The mean postoperative follow-up duration was 51±41 months. The graft survival rate of all subjects was 96.8% at 1 year, 89.9% at 3 years, 83.5% at 5 years and 74.1% at 10 years. At 6 months, BCVA significantly improved from 1.14±0.54 to 0.22±0.21 in the keratoconus group, from 1.13±0.60 to 0.44±0.54 in the herpes group, from 1.00±0.59 to 0.49±0.38 in the stromal scar group and from 1.04±0.52 to 0.32±0.29 in the corneal dystrophy group (all, p<0.0001). BCVA stabilised after 6 months thereafter up to 5 years. ECD decreased just after DALK and maintained >1000 cell/mm2 at 5 years in all groups. Conclusions DALK provides good visual acuity with slight ECD decrease over long term in all groups.

Immunological Rejection Following Allogeneic Cultivated Limbal Epithelial Transplantation

A llogeneic cultivated limbal epithelial transplantation (CLET), including living-related CLET, is recommended for bilateral cases with limbal stem cell deficiency or for unilateral cases in which the patient wishes to preserve the limbal function of the healthy fellow eye. For a long-term successful corneal epithelial restoration, it is important to maintain a suitable ocular surface environment and to prevent allograft rejection. Previous reports1-3 on allogeneic CLET have indicated only the incidence of allograft rejection, with no information on the clinical course or on anterior segment findings.Wepreviouslyexamined13patientswho underwent allogeneic CLETwithout any episodes of allograft rejection.2 The details of the epithelial sheet preparation and CLET procedures have also been outlined previously.4 Thereafter, we performed 37 allogeneic CLET procedures in 31 eyes and experienced 3 rejection episodes in 2 eyeswith characteristic clinical manifestations. Herein, we describe 2 cases who developed clinically significant allograft rejection reactions.

A Novel Entity of Corneal Diseases with Irregular Posterior Corneal Surfaces: Concept and Clinical Relevance

Various corneal diseases, such as hereditary corneal dystrophies, corneal infection, and bullous keratopathy, cause corneal opacity, scarring, and edema, leading to severely decreased visual acuity and loss of vision. These diseases were regarded as corneal opacity diseases, and the decreased visual acuity was considered to be predominantly caused by corneal opacity. The influence of corneal irregular astigmatism on vision has been poorly understood to date, mainly because accurate quantification of irregular astigmatism has been technically challenging. We have performed detailed analyses of the corneal higher-order aberrations (HOAs) of the anterior and posterior surfaces and total cornea in corneal diseases, using an anterior segment imaging system combined with a ray-tracing method. Subsequently, we conducted correlation analyses between corneal HOAs and visual acuities and characterized the typical HOA patterns in the corneal diseases. Our recent studies demonstrated that corneal HOAs directly degrade visual acuity in eyes with mild-to-moderate corneal opacities, such as corneal dystrophies, corneal scarring, and bullous keratopathy. The findings also suggested that correction of corneal HOAs using rigid gas-permeable contact lenses is effective in eyes with a smooth posterior surface and useful in certain patients with corneal scarring to some extent. Our data will be useful for decision making regarding surgical interventions, based on the amount of corneal HOAs. Our results further indicate the clinical relevance of irregular astigmatism in the posterior surfaces in assessing the visual function of eyes with various corneal diseases.