Byoung Jin Ha

Mitomycin C does not inhibit exacerbation of granular corneal dystrophy type II induced by refractive surface ablation.

Purpose: To evaluate the effect of mitomycin C (MMC) on the exacerbation of corneal opacity that occurs in patients with granular corneal dystrophy type II (GCD II) after refractive corneal surface ablation. Methods: Ten eyes of patients with GCD II who underwent refractive corneal surface ablation with MMC were compared with 10 eyes that were not treated with MMC. Best spectacle-corrected visual acuity, the degree of corneal opacity, and contrast sensitivity were evaluated at least 3 years after surgery. Corneal opacities were quantified using Pentacam densitometry maps. Results: No measured between-group value showed a statistically significant difference. Conclusion: Simultaneous application of MMC does not prevent exacerbation of GCD II after refractive corneal surface ablation.

Effect of Accommodation on Vaulting and Movement of Posterior Chamber Phakic Lenses in Eyes with Implantable Collamer Lenses

PURPOSE To investigate and compare vaulting and movement changes during accommodation in eyes with the V4c and V4 implantable collamer lenses (ICL). DESIGN Comparative, observational case series. METHODS The medical records of 35 eyes (18 patients) with the V4 ICL and 51 eyes (26 patients) with the V4c ICL were retrospectively examined and included in analyses. Anterior chamber depth (ACD), posterior corneal surface-to-ICL distance (endo-ICL distance), pupil size, and postoperative vaulting were evaluated using the Visante anterior chamber optical coherence tomography system. Images were taken during the nonaccommodative and accommodative states 3 months after ICL implantation. Refractive error, keratometry values, axial length, intraocular pressure, and central corneal thickness were evaluated at 3 months postoperatively. RESULTS ICL vaulting did not significantly change during accommodation in eyes with either the V4 or V4c ICL (P = .532 for V4 ICL and P = .415 for V4c ICL). However, significant reductions in ACD, endo-ICL distance, and pupil size were observed during accommodation in both groups. In eyes with a V4 ICL, the change in [Δ] ACD was 0.2 ± 0.1 mm (P < .001), Δendo-ICL distance was 0.2 ± 0.1 mm (P < .001), and Δpupil size was 0.5 ± 0.9 mm (P = .021). For eyes with the V4c ICL, ΔACD was 0.2 ± 0.2 mm (P < .001), Δendo-ICL distance was 0.2 ± 0.2 mm (P < .001), and Δpupil size was 0.8 ± 1.2 mm (P < .001). The mean reductions of each parameter were not statistically different between eyes with the V4 ICL and the V4c ICL. CONCLUSIONS Contrary to the light stimulation response, accommodation does not significantly affect ICL vaulting differently in eyes with either the V4 or V4C ICLs.

A Case of Inadvertent Anterior Chamber and Corneal Stromal Injection with Antibiotics during Cataract Operation

Purpose To report a case of inadvertent anterior chamber and cornea stromal injection with high dose antibiotics and steroids during cataract operation. Methods During cataract operation on a 78 year-old female patient, high dose gentamicin (20 mg/0.5 ml) and dexamethasone (2 mg/0.5 ml) were inadvertently injected into the anterior chamber and cornea stroma when making cornea edema for sealing of the incision sites. Anterior chamber irrigation with balanced salt solution (BSS) was immediately administered. On postoperative day one, extensive cornea edema was noted, and best-corrected visual acuity was 0.2. Descemets membrane folds were observed around the corneal incision sites. Topical 5% NaCl and 1% prednisolone were started. Results Four weeks postoperatively, corneal edema began to reduce significantly. At four months postoperatively, corneal edema fully resolved, and best-corrected visual acuity was 0.8. However, some Descemets membrane folds still remained, and a decrease in the number of endothelial cells was noted by specular microscope. Conclusions In this case involving anterior chamber and cornea stromal injection with high dose antibiotics and steroids, immediate anterior chamber irrigation with balanced salt solution seemed an appropriate management, and the patients long-term visual acuity appears good. To prevent such mistakes, precise labeling of all solutions and use of different syringe needles should be considered.

Biomechanical Properties of the Cornea Measured With the Dynamic Scheimpflug Analyzer in Young Healthy Adults.

Purpose: To investigate the biomechanical properties of the cornea using the dynamic Scheimpflug analyzer in young healthy adults. Methods: This prospective cross-sectional population study included 944 eyes of 472 participants aged 20 to 40 years. Participants underwent ophthalmic investigations, including evaluation of biomechanical properties of the cornea using the dynamic Scheimpflug analyzer, manifest refraction, and measurements of keratometric values by autokeratometry, intraocular pressure (IOP) by noncontact tonometer, central corneal thickness (CCT) by ultrasound, and white-to-white distance by Scheimpflug tomography. Statistical analyses included determination of the reference interval with a bootstrapping method, linear quantile mixed-effects model, and Spearman correlation analysis between the corneal biomechanical parameters and other variables (age, manifest refraction spherical equivalent, CCT, IOP, white-to-white, and keratometric values). Results: The 90% CIs of all corneal biomechanical parameters demonstrated that the ranges of the 90% CIs for the reference data were almost identical with and without bootstrapping. Quantile regression to determine the fifth, 50th, and 95th percentiles of each corneal biomechanical parameter supported the findings from the nonparametric method with the 90% CIs. Correlation analysis showed significant correlations between the parameters and variables, but there was a relatively high Spearman correlation coefficient in the case of the correlations with the CCT and IOP. Conclusions: Using data from a large population of young healthy adults, we developed a database of normal values for multiple corneal biomechanical parameters obtained from the dynamic Scheimpflug analyzer. We conclude that the biomechanical properties of the cornea are influenced by the CCT and IOP.

Photorefractive keratectomy combined with corneal wavefront-guided and hyperaspheric ablation profiles to correct myopia.

Purpose To evaluate the effects of photorefractive keratectomy (PRK) combined with corneal wavefront–guided ablation profiles and hyperaspheric ablation profiles on changes in higher‐order aberrations (HOAs). Setting Yonsei University College of Medicine and Eyereum Clinic, Seoul, South Korea. Design Comparative observational case series. Methods Medical records of patients who had corneal wavefront–guided hyperaspheric PRK, corneal wavefront–guided mild‐aspheric PRK, or non‐corneal wavefront–guided mild‐aspheric PRK were analyzed. The logMAR uncorrected distance visual acuity (UDVA), manifest refraction spherical equivalent (MRSE), and changes in corneal aberrations (root‐mean‐square [RMS] HOAs, spherical aberration, coma) were evaluated 1, 3, and 6 months postoperatively. Results The records of 61 patients (96 eyes) were reviewed. There was no statistically significant difference in logMAR UDVA or MRSE between the 3 groups at any timepoint. Corneal RMS HOAs were significantly smaller in the corneal wavefront–guided hyperaspheric group and the corneal wavefront–guided mild‐aspheric group than in the noncorneal wavefront–guided mild‐aspheric group at each timepoint. Corneal spherical aberration was significantly smaller for corneal wavefront–guided hyperaspheric PRK than for noncorneal wavefront–guided mild‐aspheric PRK 6 months postoperatively. Changes in corneal spherical aberration (preoperatively and 6 months postoperatively) in corneal wavefront–guided hyperaspheric PRK were significantly smaller than in corneal wavefront–guided mild‐aspheric PRK (P = .046). Corneal coma was significantly smaller with corneal wavefront–guided hyperaspheric PRK and corneal wavefront–guided mild‐aspheric PRK than with noncorneal wavefront–guided mild‐aspheric PRK 3 months and 6 months postoperatively. Conclusion Corneal wavefront–guided hyperaspheric PRK induced less corneal spherical aberration 6 months postoperatively than corneal wavefront–guided mild‐aspheric PRK and noncorneal wavefront–guided mild‐aspheric PRK. Financial Disclosure None of the authors has a financial or proprietary interest in any material or method mentioned.

The Comparison of Central and Mean True-Net Power (Pentacam) in Calculating IOL-Power After Refractive Surgery

Purpose To compare the accuracy of central true net corneal power (cTNP) and mean true net corneal power (mTNP) of the Pentacam system to give a keratometry (K) reading for calculating IOL (intraocular lens) power in eyes following refractive surgery. Methods Refraction, an automated K-reading (Km), cTNP and mTNP were measured for 15 eyes that required cataract surgery and had previously undergone refractive surgery. The difference between postoperative manifest refraction values and target refraction values calculated with the SRK/T formula using cTNP were compared with the one using mTNP. Results The mean deviation from the desired post-cataract refractive outcome was 0.60 diopter (D) ±0.47 (standard deviation) using cTNP; 0.75±0.54 using mTNP (p=0.386). The actual refraction was within ±0.50D of the intended refraction for 60% (cTNP) and 33.3% (mTNP) of eyes, and within ±1.00D for 93% (cTNP) and 66.7% (mTNP) of eyes. Conclusions Although not statistically significant, the cTNP showed better accuracy than mTNP to give a keratometry (K) reading for post-refractive surgery eyes requiring cataract surgery.

Comparison of Outcomes Between Combined Transepithelial Photorefractive Keratectomy With and Without Accelerated Corneal Collagen Cross-Linking: A 1-Year Study

Purpose: To investigate the effects of combined transepithelial photorefractive keratectomy (tPRK) and accelerated corneal collagen cross-linking (CXL) on visual acuity and refractive outcomes. Methods: The medical records of 89 eyes (89 patients) undergoing combined tPRK and CXL (tPRK-CXL group) or tPRK alone (tPRK group) were retrospectively analyzed. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity, and manifest refraction spherical equivalent (MRSE) were evaluated preoperatively and 2 weeks, 1, 3, 6, and 12 months after surgery. Results: At 2 weeks after surgery, the tPRK-CXL group had better UDVA than the tPRK group (0.97 ± 0.22 vs. 0.85 ± 0.22, P = 0.015). At 2 weeks and 1 month after surgery, the tPRK-CXL group had a significantly lower spherical error than the tPRK group (0.24 vs. 0.63 D, P = 0.017, for 2 weeks and 0.43 vs. 0.57 D, P = 0.019, for 1 month). At 12 months after surgery, the tPRK-CXL group had a lower spherical error and MRSE than the tPRK group (0.30 vs. 0.44 D, P < 0.001, for the spherical error and 0.17 vs. 0.31 D, P < 0.001, for the MRSE). Both groups had comparable predictability, efficacy, and safety indices at 12 months after surgery. Conclusions: Combined tPRK and accelerated CXL demonstrated comparable predictability, efficacy, and safety compared with tPRK alone. Combined tPRK and CXL provides better UDVA in the early postoperative period and better refractive outcomes at 12 months postoperatively in terms of spherical error and MRSE.

Biomechanical Properties of the Cornea Using a Dynamic Scheimpflug Analyzer in Healthy Eyes

Purpose To investigate biomechanical properties of the cornea using a dynamic Scheimpflug analyzer according to age. Materials and Methods In this prospective, cross-sectional, observational study, participants underwent ophthalmic investigations including corneal biomechanical properties, keratometric values, intraocular pressure (IOP), and manifest refraction spherical equivalent (MRSE). We determined the relationship of biomechanical parameters and ocular/systemic variables (participants age, MRSE, IOP, and mean keratometric values) by piecewise regression analysis, association of biomechanical parameters with variables by Spearmans correlation and stepwise multiple regression analyses, and reference intervals (RI) by the bootstrap method. Results This study included 217 eyes of 118 participants (20–81 years of age). Piecewise regression analysis between Corvis-central corneal thickness (CCT) and participants age revealed that the optimal cut-off value of age was 45 years. No clear breakpoints were detected between the corneal biomechanical parameters and MRSE, IOP, and mean keratometric values. Corneal velocity, deformation amplitude, radius, maximal concave power, Corvis-CCT, and Corvis-IOP exhibited correlations with IOP, regardless of age (all ages, 20–44 years, and over 44 years). With smaller deformation amplitude and corneal velocity as well as increased Corvis-IOP and Corvis-CCT, IOP became significantly increased. We provided the results of determination of confidence interval from RI data using bootstrap method in three separate age groups (all ages, 20–44 years, and over 44 years). Conclusion We demonstrated multiple corneal biomechanical parameters according to age, and reported that the corneal biomechanical parameters are influenced by IOP.

Rotational Stability and Visual Outcomes of V4c Toric Phakic Intraocular Lenses

PURPOSE To investigate the clinical outcomes and rotational stability following implantation of V4c toric implantable collamer lenses (ICLs) (STAAR Surgical Company, Monrovia, CA) and to analyze the factors that influence rotational stability. METHODS In this prospective observational case series, the authors analyzed the visual outcomes and rotational stability in 52 eyes of 52 patients immediately and 3 and 6 months after implantation. Postoperative rotation was defined as the angle between the adjusted axis and alignment axis. Central vaulting of the ICL was measured in a non-accommodative state using Visante optical coherence tomography (Carl Zeiss Meditec, Jena, Germany). Vector analysis of refractive astigmatism was performed. Regression analysis was used to investigate the association between the degree of rotation 6 months postoperatively and the associated variables. RESULTS The mean efficacy index and safety index 6 months postoperatively were 1.35 ± 0.19 and 1.38 ± 0.22, respectively. In vector analysis, the magnitude of error was -0.20 diopters (D), indicating slight undercorrection. Absolute degree of rotation was 2.81° ± 1.87° immediately after the operation and 3.75° ± 2.92° and 3.87° ± 3.07° at 3 and 6 months postoperatively, respectively (P = .009). Bonferroni-adjusted post-hoc comparison showed that the absolute degree of rotation immediately after the operation was significantly smaller than that after 3 (P = .043) and 6 (P = .023) months, with barely any change after 3 months. No explanatory variable relevant to the absolute degree of rotation was discovered. CONCLUSIONS The V4c toric ICL is predictable, safe, and effective in correcting low and high levels of astigmatism, showing relatively good postoperative rotational stability. [J Refract Surg. 2018;34(7):489-496.].