Characteristics of higher-order aberrations and anterior segment tomography in patients with pathologic myopia.

PURPOSE: To investigate prospectively the characteristics in the higher-order aberrations and anterior segment tomography in patients with pathologic myopia. METHODS: One hundred and twelve consecutive highly myopic patients (mean age 43.4 ± 9.3 years, spherical equivalent of refractive error ≥8 D and an axial length ≥26.5 mm) were studied. Thirty-seven emmetropic individuals (mean age 37.0 ± 14.5 years, spherical equivalent of refractive error ≤ ±1 D) were analyzed as controls. The ocular and cornea higher-order aberrations were measured using a Hartmann-Shack wavefront sensor (KR-1W; Topcon Corporation, Tokyo, Japan). The crystalline lens rise, the angle-to-angle, and the white-to-white values were measured using anterior segment OCT (SS-1000; Tomey Corporation, Nagoya, Japan). The mean curvature of the anterior corneal surface, the thickness at the thinnest central corneal point, the location of the central corneal point, the corneal volume, the anterior chamber volume, and the anterior chamber depth were measured using the Pentacam HR (Oculus, Inc., Wetzlar, Germany). RESULTS: The ocular total higher-order aberration for 4-mm pupil, the ocular spherical aberrations, and internal spherical aberration for 6-mm pupil were significantly higher in highly myopic eyes than in the emmetropic controls. The crystalline lens rise was significantly smaller in highly myopic eyes than in the emmetropic controls. The anterior chamber depth and the anterior chamber volume were significantly larger in highly myopic eyes than in the emmetropic controls. CONCLUSION: Highly myopic eyes had higher-order aberrations than emmetropic eyes because of the increasing internal aberrations.

Phacoemulsification with vitreous loss using phacoemulsifier and vitrector concurrently: bimanual-bipedal technique.

Vitreous loss is one of the adverse complications that can occur during phacoemulsification. Once vitreous loss is identified, procedural guidelines advise that phacoemulsification be ceased and the probe carefully withdrawn to minimize traction on the vitreous. Bimanual-bipedal technique described in this study holds the phacoemulsification probe in place and inserts the vitrectomy cutter through the pars plana port with the other hand. After removal of vitreous around the phacoemulsification tip, the vitrectomy cutter is switched to a cutting rate of zero. phacoemulsification can then be resumed with the vitrectomy cutter as a retainer of the lens fragments, similar to the hook of bimanual technique. Lens fragments are synergistically retained through aspiration between the vitrectomy cutter and phacoemulsification probe to prevent displacement. The bimanual-bipedal technique may offer a more streamlined and potentially safer approach for phacoemulsification with vitreous loss.

Evaluation of corneal biomechanics in patients with keratectasia following LASIK using dynamic Scheimpflug analyzer.

PURPOSE: To investigate the corneal biomechanics in eyes with keratectasia following LASIK using a dynamic Scheimpflug analyzer. DESIGN: Case-Control study. METHOD: The subjects in the study included 12 eyes with keratectasia after LASIK (KE), 24 eyes with keratoconus (KC), 17 eyes without keratectasia after LASIK (LASIK), and 34 eyes with normal corneas (Normal). Corneal biomechanics of the four groups were evaluated using a dynamic Scheimpflug analyzer. RESULTS: Compared with Normal (7.06 ± 0.54), the radius at the highest concavity (radius, mm) of LASIK (5.96 ± 0.76), KE (4.93 ± 0.61) and KC (5.39 ± 1.02) were significantly small. The Deflection Amplitude (HCDLA, mm) of Normal (0.94 ± 0.07) was significantly lower than those of KE (1.11 ± 0.10) and KC (1.06 ± 0.16), and was not significantly different from that of LASIK (0.98 ± 0.07). There were significant differences between LASIK and KE in radius and HCDLA (P < 0.05), whereas KE and KC had no differences in these parameters. CONCLUSIONS: Corneal biomechanical features evaluated using the dynamic Scheimpflug analyzer suggest that biomechanical properties in eyes with keratectasia, keratoconus, and LASIK are different from those of normal eyes. Although the biomechanics in eyes with keratectasia differs from that in eyes with LASIK, it is similar to that in eyes with keratoconus.

Visual Performance and Optical Quality of Standardized Asymmetric Soft Contact Lenses in Patients With Keratoconus.

Purpose: To evaluate the visual performance and optical quality of a standardized asymmetric soft contact lens (SCL) used for correction of higher-order aberrations (HOAs) in eyes with keratoconus. Methods: We included 30 eyes (26 patients) with keratoconus (average K: 45.7 ± 2.3 diopters [D]). The patients were subjected to corneal tomography, aberrometry, measurements of manifest refraction and visual acuity (VA), and visual analog scale (VAS) assessments. The study lenses were made using a molding method and consisted of six standardized types, in which an asymmetric power distribution of approximately 2 to 12 D (2-D step) was used to correct HOAs. The lens type suitable for each eye was selected based on the corneal tomography and aberrometry data. The on-eye performance of the lens was evaluated using aberrometry (4-mm pupil), over refraction, VA, and VAS. Results: The standardized asymmetric SCL improved the best spectacle-corrected VA from -0.07 ± 0.09 to -0.11 ± 0.08 logMAR (P < 0.05) and the mean VAS score from 66.2 ± 21.8 to 75.4 ± 20.5 (P < 0.05). Vertical coma decreased significantly (-0.50 ± 0.36 µm without SCL; -0.36 ± 0.34 µm with SCL; P < 0.01). In subgroup analysis, subjects in the high VAS group (score ≥ 75) accounted for 70% of all subjects, and this was the group in which the vertical coma decreased significantly from the level without the lens. Conclusions: A standardized asymmetric SCL can reduce HOAs and improve vision quality when compared with spectacles in patients with keratoconus who wear rigid gas-permeable lenses.

[Calcification on the posterior surface of an implanted silicone intraocular lens in a patient with asteroid hyalosis].

BACKGROUND: Calcification on the surface of the hydrogel intraocular lens (IOL) has been reported, but the mechanism of the surface calcification is not fully understood. We report a case of surface calcification on an implanted silicone IOL. The purpose of our study was to examine the clinical and ultrastructural findings associated with the late surface calcification of a silicone IOL. CASE: A 70-year-old Japanese man had undergone cataract surgery in his left eye, with uneventful phacoemulsification and silicone IOL (Allergan SI-55 NB) implantation with the manufacturer's cartridge and injector. He was referred again 29 months later with blurred vision, glare sensitivity, and decreased vision in his left eye. He was diagnosed as having aftercataract. Although YAG laser capsulotomy was performed, the opacity on the posterior surface gradually increased. The opacity was located mainly within the capsulotomy window on the posterior surface of the lens, although the patient maintained good visual acuity. LV : 0.2 (1.0 x S-2.0 D). The lens was removed 46 months after the initial surgery. Scanning electron microscopy (SEM) showed membranous deposits on the posterior optical surface of the silicone lens. There were high levels of phosphoric acid (P) and calcium (C) confirming calcification of the silicone IOL. Asteroid hyalosis was observed in the fellow eye of the patient. CONCLUSION: This is the first report of surface calcification of a silicone IOL in Japan. Although the mechanism of the calcification has not been determined, careful clinical follow-up of patients implanted with silicone lenses is necessary to determine if this phenomenon is rare and sporadic or if it may be more widespread. Since 5 similar cases of calcification in silicone lenses with accompanying asteroid hyalosis have been reported in other countries, we can conclude that silicone lens implantation in eyes with asteroid hyalosis should be avoided.

Quantitative Evaluation of the Natural Progression of Keratoconus Using Three-Dimensional Optical Coherence Tomography.

PURPOSE: We quantified the chronologic progression of keratoconus using anterior segment optical coherence tomography (AS-OCT). METHODS: A total of 217 eyes from 113 patients with keratoconus, keratoconus suspect, or forme fruste keratoconus were evaluated by corneal tomography using swept-source OCT. Age-dependent changes in the radius of the posterior best-fit sphere (Rpost), minimum corneal thickness (Tmin), and distance from the thinnest point to the corneal vertex (Dmin) were examined over follow-up periods of up to 5.79 years and were analyzed using generalized estimating equation (GEE) nonlinear regression model. RESULTS: Annual changes in Rpost (mean, -0.017 mm) and Tmin (-2.69 µm) were significantly higher in younger patients (P < 0.01, GEE nonlinear regression) and in patients with higher maximal K value (Kmax; P < 0.01, GEE nonlinear regression), whereas no changes were observed in Dmin. Even in patients 30 years or older, 14% of eyes revealed remarkable progression in Rpost. In eyes with acute hydrops, annual changes in Rpost (-0.22 mm) and Tmin (-33.8 µm) before acute corneal hydrops were more than 10 times faster than those in other eyes (P < 0.001, GEE nonlinear regression). CONCLUSIONS: Chronologic measurements of corneal tomography in keratoconus demonstrated that the progression of steepening at posterior corneal surface was found not only in patients under 30 years but also in older patients, particularly in advanced keratoconus. The rate of progression can be measured by mapping of corneal curvature and thickness using OCT, and the risk of progression was greater in younger patients with steeper Kmax.

Corneal topographic analysis of patients with Mooren ulcer using 3-dimensional anterior segment optical coherence tomography.

PURPOSE: To investigate the corneal topography and visual function of patients with Mooren ulcer using 3-dimensional anterior segment optical coherence tomography (3-D AS-OCT). METHODS: Fourteen eyes of 9 patients with Mooren ulcer were studied. Pachymetric and axial power maps were obtained by 3-D AS-OCT. The axial power maps were classified into 3 patterns by visual inspection. The distribution of the corneal dioptric power was analyzed by Fourier harmonic expansion. The magnitudes of the spherical component, asymmetry, regular astigmatism, higher-order irregularity, and radial distance from the corneal vertex to the thinnest point of the lesion were determined. RESULTS: The axial power maps of 9 eyes were classified into arcuate patterns, 4 into crab-claw patterns, and 1 eye into an intermediate pattern. The radial distance from the corneal vertex to the thinnest point of the lesion was significantly shorter in the crab-claw pattern group than in the arcuate pattern group (P = 0.007). The magnitudes of asymmetry, regular astigmatism, and higher-order irregularity of the crab-claw pattern group were significantly greater than those of the arcuate pattern group (P = 0.017, P = 0.011, and P = 0.030, respectively). CONCLUSIONS: Three-dimensional AS-OCT is able to evaluate the corneal topography of opacified peripheral lesions in eyes with Mooren ulcer, and the results showed that irregular astigmatism is higher when the lesion is closer to the center of the cornea.

Characteristics of corneal topographic and pachymetric patterns in patients with pellucid marginal corneal degeneration.

PURPOSE: To determine the characteristics of the shape of the cornea in patients with pellucid marginal corneal degeneration (PMD) and to compare these characteristics to those of eyes with keratoconus and eyes of normal subjects. METHODS: This was a retrospective, cross-sectional case-series in which 49 eyes of 33 patients with PMD, 51 eyes of 51 patients with keratoconus and 53 eyes of 53 subjects with normal corneas (controls) were examined and compared. For all eyes, we obtained the topographic patterns of the axial power maps, anterior and posterior elevation maps and pachymetric maps using a rotating Scheimpflug camera. The eyes were classified into the respective patterns by visual inspection of these maps. RESULTS: In eyes with PMD, the most common axial power map pattern was the crab claw pattern (78 %) followed by the inferior steepening pattern (18 %). In eyes with keratoconus, the most common pattern was the inferior steepening pattern (67 %). The most common pattern in the elevation maps for both surfaces was the asymmetric island in eyes with PMD and keratoconus. Although the decentered pattern, including the decentered oval (27 %) and decentered round (20 %) pattern, on pachymetric map was specific to eyes with PMD, the incidence of these patterns was relatively low. CONCLUSIONS: The similarity in the topographic and pachymetric patterns in eyes with PMD and keratoconus suggests that they may be a continuity of the same disorder with different phenotypes.

Evaluation of corneal epithelial and stromal thickness in keratoconus using spectral-domain optical coherence tomography.

PURPOSE: We sought to assess the corneal thickness of the epithelium and stroma in keratoconic and normal eyes by spectral-domain optical coherence tomography (SD-OCT). METHODS: Fifty-seven keratoconic and 20 normal eyes were studied. The eyes were examined by SD-OCT, and the keratoconic eyes were subdivided into 2 groups: those showing only smooth corneal thinning and corneal protrusion on the image (KC1 group) and those showing abnormalities in the Bowman layer or in the stroma, or in both (KC2 group). The thicknesses at the corneal vertex and at the superior, inferior, nasal, and temporal cornea 1.5 mm from the corneal vertex in the KC1 group were compared with those in the normal group. The OCT findings in the KC2 group were described. RESULTS: The epithelial thickness at the corneal vertex and at the inferior and temporal cornea, and the stromal thickness at all points were significantly thinner in the KC1 group than in the normal group (p < 0.05). The epithelial and stromal thicknesses at the corneal vertex were significantly correlated in the KC1 group and the normal group (r (2)  = 0.427, p < 0.0001).The epithelial thickness in the KC2 group was not uniform owing to Bowman layer scarring, stromal scars, and secondary corneal amyloidosis. CONCLUSIONS: Although epithelial thinning is associated with stromal thinning, when the cornea remains clear, the epithelial thickness may vary because of the irregularity of the stroma beneath the epithelium in patients with keratoconus.

Corneal biomechanical properties in 3 corneal transplantation techniques with a dynamic Scheimpflug analyzer.

PURPOSE: To compare the corneal biomechanical properties of eyes that have undergone penetrating keratoplasty (PK), deep anterior lamellar keratoplasty (DALK), and Descemet stripping automated endothelial keratoplasty (DSAEK). METHODS: This case-control study comprised 20 post-PK eyes, 14 post-DALK eyes, 15 post-DSAEK eyes, and 50 normal control eyes. A dynamic Scheimpflug analyzer (the Corvis ST) was used to evaluate the corneal biomechanical properties including deformation amplitude (DA) and radius at the highest concavity (R hc). RESULTS: In post-PK eyes, the mean DA was 1.20 ± 0.13 mm, which was significantly higher than those of the control eyes (1.07 ± 0.09) and the post-DSAEK eyes (1.08 ± 0.12). The DA (1.18 ± 0.18) in the post-DALK eyes was significantly higher than in the control eyes. The R hc in the post-PK (6.34 ± 0.37 mm), -DALK (6.04 ± 1.22), and -DSAEK (6.44 ± 0.58) eyes was significantly smaller than in the control eyes (7.57 ± 0.78). CONCLUSIONS: The dynamic Scheimpflug analyzer provides a method to obtain new biomechanical information on the cornea such as the DA and R hc, and these parameters differed among eyes that had undergone 3 different types of corneal surgery. Abnormalities in these parameters after the different corneal transplantation techniques may indicate larger deviations in the stress-strain reaction of the cornea and more uncertainty in the intraocular pressure measurements than in normal eyes.

Corneal topographic analysis by 3-dimensional anterior segment optical coherence tomography after endothelial keratoplasty.

PURPOSE: To investigate the characteristics of the corneal topography with three-dimensional (3-D) anterior segment optical coherence tomography (AS-OCT) following Descemet's stripping automated endothelial keratoplasty (DSAEK). METHODS: Thirty-four eyes of 33 patients following DSAEK were studied. In addition to conventional topographic maps, the elevation map of the intrastromal interface and pachymetric maps of the host and graft were obtained by corneal topographic analysis using 3-D AS-OCT. The coefficient of variation of the corneal power (CV-Pa, CV-Pp) and root mean squares of the corneal elevation (RMS-Ea, RMS-Ep) of the anterior and posterior corneal surfaces were determined. Based on the combination of the regularity and irregularity of the anterior and posterior surfaces, subjects were classified into four types: type 1, regular/regular; type 2, irregular/regular; type 3, regular/irregular; and type 4, irregular/irregular. RESULTS: The average graft decentration was 0.59 ± 0.23 mm. The proportion of types 1, 2, 3, and 4 were 59%, 9%, 24%, and 9 %, respectively. The CV-Pa (25.8 ± 8.9) and CV-Pp (-73.9 ± 18.0) of the type 1 corneas were significantly better than that of type 2 and type 3 corneas, respectively. The RMS-Ea (5.1 ± 1.3) and RMS-Ep (26.0 ± 7.3) of the type 1 corneas were significantly better than that of type 2 and type 3 corneas. CONCLUSIONS: An OCT-based corneal topographer might be useful in determining the factors associated with optical quality of the cornea following DSAEK by analyzing the topographic characteristics of host and donor separately.