Kazutaka Kamiya

Corneal biomechanical properties in normal-tension glaucoma

Purpose:  To investigate the intraocular pressure (IOP) and corneal biomechanical properties of normal and normal‐tension glaucoma (NTG) eyes.

Corneal forward shift after excimer laser keratorefractive surgery

The excimer laser keratorefractive surgery inevitably compromises structural integrity of the cornea by the surgical tissue subtraction and loss of integrity of Bowman’s membrane. Forward shift of the cornea is commonly seen after both photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). Antero-posterior movement of the cornea is evaluated by measuring the posterior corneal elevation with the scanning-slit corneal topography (Orbscan). Eyes with thinner cornea, higher intraocular pressure, and higher myopia requiring greater laser ablation were more predisposed to forward shift of the cornea. After PRK, there was a trend toward progressive forward shift of the cornea, but the progression stabilized 6 months after surgery. Because progressive thinning and expansion of the cornea were not observed during the one-year observation period after PRK, the forward shift of the cornea does not represent true ectasia. Forward shift of both corneal surfaces would add to the tendency toward myopic regression after excimer laser surgery.

Evaluation of corneal elevation, pachymetry and keratometry in keratoconic eyes with respect to the stage of Amsler-Krumeich classification

Aim To evaluate corneal elevation, pachymetry and keratometry in keratoconic eyes according to the clinical stage of the disease. Methods This prospective comparative study was performed on one hundred and twenty-six eyes of 83 patients who had keratoconus, and 42 normal eyes of 42 age-matched subjects. Corneal elevation, pachymetry and keratometry were measured using a rotating Scheimpflug camera (Pentacam HR, Oculus) in these eyes. The area under the receiver operating characteristic (AUROC) curves was used to analyse the diagnostic significance of these parameters, with respect to each stage of Amsler-Krumeich classifications. AUROC was calculated to describe the predictive accuracy of the different indices and to determine the cut-off points where sensitivity and specificity were maximised. Results Posterior (0.980) and anterior (0.977) elevation differences showed the highest AUROCs, followed by dioptres (D) value (0.941), percentage thickness increase (PTI) 2 mm (0.931), PTI 4 mm (0.927), progression index (0.927), minimal pachymetry (0.923), average keratometry (0.914), anterior elevation (0.909), PTI 6 mm (0.906), posterior elevation (0.898), central pachymetry (0.889), PTI 8 mm (0.870), PTI 10 mm (0.864), corneal thickness spatial profile 2 mm (0.835) and cylinder (0.796). The differences in AUROC curves between anterior and posterior elevation difference measurements and other diagnostic parameters tended to be larger at the earlier stages of keratoconus. Conclusions Anterior and posterior corneal surface height data obtained by enhanced ectasia display, effectively discriminates keratoconus from normal corneas. Elevation difference measurements may provide useful information for improving the diagnostic accuracy of keratoconus, especially in the early stage of the disease.

Relationship between ciliary sulcus diameter and anterior chamber diameter and corneal diameter

PURPOSE: To evaluate the relationship between the horizontal ciliary sulcus diameter and anterior chamber diameter measured by 35 MHz ultrasound biomicroscopy (UBM) and the horizontal corneal diameter (white to white [WTW]) measured by scanning‐slit topography and to assess the repeatability (intraexaminer difference) of the 2 methods. SETTING: Department of Orthoptics and Visual Science, Kitasato University School, Sagamihara, Japan. METHODS: The repeatability and agreement of UBM and scanning‐slit topography were assessed using the intraclass correlation (ICC) and the Bland and Altman method (ie, mean difference and 95% limits of agreement [LoA]). RESULTS: Thirty‐one normal eyes of 31 subjects (mean age 22.6 years ± 4.8 [SD]) were evaluated. The mean differences between the repeated measurements were as follows: ciliary sulcus diameter, −0.05 mm (95% LoA, −0.38 to 0.28 mm); anterior chamber diameter, 0.02 mm (95% LoA, −0.42 to 0.45 mm); and WTW diameter, −0.02 mm (95% LoA, −0.18 to 0.13 mm). The agreement between ciliary sulcus diameter and WTW diameter was poor (ICC, 0.679). The mean difference was 0.41 mm (95% LoA, −0.46 to 1.28 mm). The agreement between the ciliary sulcus diameter and anterior chamber diameter was high (ICC, 0.918). The mean difference was 0.13 mm (95% LoA, −0.41 to 0.67 mm). CONCLUSION: Results suggest that direct measurement of the ciliary sulcus by UBM would reduce the percentage of complications related to intraocular lens sizing over the percentage when sizing is based on WTW diameter. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Long-Term Comparison of Posterior Chamber Phakic Intraocular Lens With and Without a Central Hole (Hole ICL and Conventional ICL) Implantation for Moderate to High Myopia and Myopic Astigmatism: Consort-Compliant Article.

AbstractThe study shows a promising next-generation surgical option for the correction of moderate to high ametropia. Hole implantable collamer lens (ICL), STAAR Surgical, is a posterior chamber phakic intraocular lens with a central artificial hole. As yet, however, no long-term comparison of the clinical results of the implantation of ICLs with and without such a hole has hitherto been conducted. A prospective, randomized, controlled trial was carried out in order to compare the long-term clinical outcomes of the implantation, in such eyes, of ICLs with and without a central artificial hole.Examinations were conducted of the 64 eyes of 32 consecutive patients with spherical equivalents of −7.53 ± 2.39 diopters (D) (mean ± standard deviation) in whom implantation of a Hole ICL was performed in 1 eye, and that of a conventional ICL was carried out in the other, by randomized assignment. Before 1, 3, and 6 months, and 1, 3, and 5 years after surgery, the safety, efficacy, predictability, stability, intraocular pressure, endothelial cell density, and adverse events of the 2 surgical techniques were assessed and compared over time.The measurements of LogMAR uncorrected and corrected distance visual acuity 5 years postoperatively were −0.17 ± 0.14 and −0.24 ± 0.08 in the Hole ICL group, and −0.16 ± 0.10 and −0.25 ± 0.08 in the conventional ICL group. In these 2 groups, 96% and 100% of eyes, respectively, were within 1.0 D of the targeted correction 5 years postoperatively. Manifest refraction changed by −0.17 ± 0.41 D and −0.10 ± 0.26 D occurred in from 1 month to 5 years in the Hole and conventional ICL groups, respectively. Only 1 eye (3.1%), which was in the conventional ICL group, developed an asymptomatic anterior subcapsular cataract.Both Hole and conventional ICLs corrected of ametropia successfully throughout the 5-year observation period. It appears likely that the presence of the central hole does not significantly affect these visual and refractive outcomes.Trial Registration: UMIN000018771.

Effect of Intraocular Forward Scattering and Corneal Higher-Order Aberrations on Visual Acuity after Descemet’s Stripping Automated Endothelial Keratoplasty

Purpose To assess the relationship of intraocular forward scattering and corneal higher-order aberrations (HOAs) with best spectacle corrected visual acuity (BSCVA) after Descemet’s stripping automated endothelial keratoplasty (DSAEK), and to compare these parameters between DSAEK and non-Descemet’s stripping automated endothelial keratoplasty (n-DSAEK) groups. Methods This retrospective study enrolled thirty eyes of 30 consecutive patients who underwent standard DSAEK, and who underwent successful phacoemulsification with intraocular lens implantation before DSAEK. The mean age at the time of surgery was 71.7 ± 10.4 years. We quantitatively evaluated the objective scattering index (OSI) using the double-pass instrument (OQAS II, Visiometrics) and corneal HOAs using Hartmann-Shack aberrometry (KR-9000PW, Topcon) 3 months postoperatively. Results The mean OSI, corneal HOAs, and logMAR BSCVA 3 months after DSAEK were 7.91 ± 3.58, 0.43 ± 0.27 μm, and 0.32 ± 0.25, respectively. We found a significant correlation between the OSI and logMAR BSCVA (Spearman correlation coefficient r=0.714, p<0.001), but no significant association between corneal HOAs and logMAR BSCVA 3 months postoperatively (r=0.209, p=0.267). We found no significant differences in any postoperative parameters between the DSAEK and n-DSAEK groups (p>0.05). Conclusions Our pilot study demonstrated that the postoperative corrected visual acuity was significantly correlated with intraocular forward scattering, but not with corneal HOAs in post-DSAEK eyes, suggesting that intraocular forward scattering plays a more essential role in postoperative visual performance than corneal aberrations after DSAEK. The detailed visual performance, such as HOAs and intraocular scattering, after n-DSAEK appears to be essentially equivalent to that after DSAEK.

Progression of Pellucid Marginal Degeneration and Higher-Order Wavefront Aberration of the Cornea

PURPOSE To report the time course of changes in corneal wavefront aberrations in a patient with pellucid marginal degeneration. CASE A 59-year-old man with pellucid marginal degeneration was followed-up annually with slit-lamp microscopy and videokeratography for 11 years. The anterior corneal height data of the videokeratography were expanded into the set of orthogonal Zernike polynomials to calculate wavefront aberrations for the central 3-mm cornea. OBSERVATIONS Although the patient complained of gradual deterioration of vision, there was no evident sign of disease progression on slit-lamp examination and visual acuity measurement. Color-coded maps of videokeratography showed slight deterioration over time, but no remarkable and decisive changes were seen. Coma-like aberration displayed a gradual, but apparent increase with a 1.67-fold worsening (0.473 microm to 0.792) during the 11-year follow-up period. Spherical-like aberration remained almost stable throughout the observation period. There were no obvious changes in crystalline lens and retina. CONCLUSIONS The results suggest that increases in coma-like aberrations of the cornea reflect the subclinical progression of pellucid marginal degeneration over the years.

Dry Eye After Small Incision Lenticule Extraction and Femtosecond Laser-Assisted LASIK: Meta-Analysis.

Purpose: To compare postoperative ocular surface integrity and innervation between small incision lenticule extraction (SMILE) and femtosecond laser–assisted laser in situ keratomileusis (FS-LASIK). Methods: The Cochrane Central Register of Controlled Trials, PubMED, and EMBASE were searched for prospective comparative studies. Trials meeting the selection criteria were quality appraised, and the data were extracted by 2 independent authors. The weighted mean differences (WMDs) and 95% confidence intervals (CIs) were used to compare dry eye examinations and corneal subbasal nerve density (SMILE—FS-LASIK). Results: The study covered 5 trials. No significant difference was found in the Schirmer test score between both groups (WMD = −1.91 and 0.27; 95% CI, −5.02 to 1.20 and −0.99 to 1.54; P = 0.23 and 0.67 at 1- and 6-month follow-ups, respectively). Tear breakup time in the SMILE group significantly exceeded that in the FS-LASIK group (WMD = 0.65 and 1.14; 95% CI, 0.20–1.10 and 0.18–2.10; P = 0.004 and 0.02, at 1- and 6-month follow-ups, respectively). Ocular surface disease index scores were significantly better in the SMILE group 6 months postoperatively (WMD = −10.12, 95% CI, −16.07 to −4.18, P = 0.0008). No significant difference was found in tear osmolarity between both groups (WMD = −5.19 and −6.37; 95% CI, −17.15 to 6.76 and −22.74 to 10.00; P = 0.39 and 0.45 at 1- and 6-month follow-ups, respectively). Higher corneal sensitivity was observed in the SMILE group 1 and 6 months postoperatively (WMD = 11.35 and 3.49; 95% CI, 7.29–15.40 and 1.76–5.21; P < 0.00001 and <0.0001, at 1- and 6-month follow-ups, respectively). Corneal subbasal nerve density was also significantly higher in SMILE-treated eyes than it was in FS-LASIK-treated eyes 1 month postoperatively (WMD = 4.72, 95% CI, 1.10–8.34, P = 0.01). Conclusions: According to this meta-analysis, the SMILE procedure has fewer negative impacts on the ocular surface and corneal innervation than does FS-LASIK. Furthermore, SMILE shows superiority over FS-LASIK by a exhibiting a lower risk of postoperative dry eye.

Effect of Light Scattering and Higher-order Aberrations on Visual Performance in Eyes with Granular Corneal Dystrophy.

This study was aimed to assess the relationship of intraocular forward scattering, corneal backward scattering, and corneal higher-order aberrations (HOAs) with corrected distance visual acuity (CDVA) in eyes with granular corneal dystrophy (GCD). We retrospectively examined forty two eyes of 42 consecutive patients who diagnosed GCD, and age-matched 20 eyes of 20 healthy subjects. We assessed objective scattering index (OSI) using the double-pass instrument (OQAS II, Visiometrics), corneal densitometry (CD) using the Scheimpflug rotating camera (Pentacam HR, Oculus), and corneal HOAs using the Hartmann-Shack aberrometry (KR-9000, Topcon). The OSI, CD, and corneal HOAs were significantly larger in the GCD group than those in the control group (Mann-Whitney U test, p < 0.001). We found significant correlations of logMAR CDVA with the OSI (Spearman correlation coefficient r = 0.577, p < 0.001), and with the CD (r = 0.340, p = 0.028), but no significant association with corneal HOAs (r = 0.061, p = 0.701). Intraocular forward scattering, corneal backward scattering, and corneal HOAs in eyes with GCD were higher than that in normal eyes. The CDVA was significantly correlated with intraocular forward scattering, but not with corneal HOAs in eyes with GCD, suggesting that light scattering, especially forward scattering, plays a more vital role in visual performance than corneal aberrations in eyes with GCD.

Relationship of corneal asphericity to intraocular lens power calculations after myopic laser in situ keratomileusis

Purpose To examine whether corneal asphericity affects underestimation in the SRK/T intraocular lens (IOL) power calculation after myopic laser in situ keratomileusis (LASIK) and to evaluate the predictability of IOL power underestimation using the asphericity. Setting Kitasato University, Kanagawa, and Miyata Eye Hospital, Miyazaki, Japan. Design Retrospective case series. Methods The clinical records of eyes that had IOL implantation during cataract surgery after previous myopic LASIK between May 2008 and October 2014 were reviewed. For eyes with an available clinical history, the effect of manifest refraction spherical equivalent before LASIK, axial length, and the asphericity (Q value) on cataract surgery and the refractive error in the use of the SRK/T formula were examined using stepwise multiple regression analysis. Predictions with the resultant regression equation and significant factors were evaluated with Bland‐Altman plots. Results Fifty‐four eyes of 37 patients were included. The mean duration from LASIK to cataract surgery was 9.1 years ± 3.5 (SD) (range 2 to 14 years). Multiple regression analysis using 22 eyes of 22 patients resulted in a significant factor, which was the Q value (P < .001, R2 = 0.80). The refractive errors in 53 eyes were predicted with tolerances of 64.5% and 87.0% within ±0.5 diopter (D) and within ±1.0 D, respectively. Bland‐Altman analysis showed that 95% of the limitation range was 2.59 D. Conclusions The corneal asphericity after myopic LASIK significantly correlated with the IOL power underestimation with use of the SRK/T formula. The refractive error could also be predicted well with the use of asphericity. Financial Disclosure None of the authors has a financial or proprietary interest in any material or method mentioned.