Eui Sang Chung

Homozygous granular corneal dystrophy type II (Avellino corneal dystrophy): natural history and progression after treatment.

Purpose: To describe the clinical features of homozygous granular corneal dystrophy type II (GCDII) with age and with several kinds of treatment in 18 homozygous patients in several different conditions. Methods: Eighteen homozygous GCDII patients, confirmed with DNA analysis, of 13 families were enrolled. Their clinical features that include age at detection by parents, visual acuity, and disease progression were evaluated. We also studied the recurrence patterns for the 13 patients who underwent phototherapeutic keratectomy, penetrating keratoplasty, lamellar keratoplasty, or deep lamellar keratoplasty. Results: The age at detection by the parents ranged from 3 to 5 years; visual loss begins in childhood with progression into the 20s. All of the patients who had undergone surgeries acquired better vision immediately after surgery. Corneal deposits reappeared soon after treatments. Recurrences became progressively more rapid and severe with treatments. Conclusions: The clinical features of homozygous GCDII are characterized by a severe granular type of corneal dystrophy with an early onset and rapid progression. After surgical treatment, recurrence is rapid and severe.

Prevalence of Granular Corneal Dystrophy Type 2 (Avellino Corneal Dystrophy) in the Korean Population

Purpose: This study investigates the prevalence of granular corneal dystrophy type 2 (GCD2; Avellino corneal dystrophy) in the Korean population. Methods: GCD2 homozygotes were identified through a collaboration of Korean referral centers for corneal disease. The genetic status of the patients and their immediate families were verified by DNA analysis. A lower bound for the gene prevalence was calculated using a model based on the Hardy-Weinberg principle. A second population-based model was developed to correct for known underestimation in the primary model. The corrected model used population data from the 2005 Korean census and fertility rates from historical Korean census data. Results: We identified 21 individuals homozygous for GCD2 (R124H mutation) from 16 Korean families. From this, we estimate that the overall prevalence (combining heterozygotes and homozygotes) is at least 8.25 affected persons/10,000 persons. Our corrected estimate for overall prevalence is 11.5 affected persons/10,000 persons. Conclusion: We present the first estimate of the prevalence of GCD2. Although uncommon, the prevalence of GCD2 in Korea is greater than anticipated. We believe that our approach could potentially be applied to estimating the prevalence of other rare diseases.

Ethical and regulatory guidelines in clinical trials of xenocorneal transplantation in Korea; the Korean xenocorneal transplantation consensus statement

To establish the consensus about the conditions for undertaking clinical trials in xenocorneal transplantation in Korea, specific issues regarding the xenocorneal transplantation on ethical and regulatory aspects are addressed, and the guidelines to conduct clinical trial of the xenocorneal transplantation are proposed.

Prospective contralateral eye study to compare 80- and 120-μm flap LASIK using the VisuMax femtosecond laser.

PURPOSEnTo compare visual outcomes and flap stability of LASIK with ultrathin 80- and 120-μm flaps created with a VisuMax femtosecond laser (Carl Zeiss Meditec, Jena, Germany) for moderate to high myopia and to evaluate the effect of corneal flap thickness on outcomes.nnnMETHODSnIn a prospective contralateral eye study, 36 consecutive patients (72 eyes) underwent bilateral LASIK for myopia ranging from -2.00 to -10.00 diopters using the VisuMax femtosecond laser and MEL-80 excimer laser (Carl Zeiss Meditec). One eye of each patient was randomized to have the 80-μm flap and the other to the 120-μm flap created with 200-kHz VisuMax femtosecond laser. Preoperative and postoperative tests included visual acuity, manifest refraction, contrast sensitivity, and flap thickness measured by anterior segment optical coherence tomography. Main outcomes and complications were checked at postoperative 1 week and 1, 3, and 6 months.nnnRESULTSnThere were no differences in visual outcome, residual refractive error, or contrast sensitivity between groups during follow-up, except for better uncorrected visual acuity at postoperative 1 day in the 120-μm group. Mean standard deviations of measured flap thickness during follow-up ranged from 3.16 to 3.80 μm in both groups. Opaque bubble layer, a unique complication in femtosecond LASIK, was more frequent in the 80-μm group (7 of 36: 19%) than in the 120-μm flap group (3 of 36: 8%) without a statistically significant difference (P = .301) and was related to thicker central cornea and steeper keratometric value, although it did not influence clinical results. Comparison of the intended versus achieved correction showed no significant differences between groups.nnnCONCLUSIONSnLASIK using the VisuMax femtosecond laser supplied good clinical results and flap reproducibility in both the 80- and 120-μm flap groups. Patients with relatively thin cornea may benefit from 80-μm flap LASIK.

Expression of neurotrophic factors and their receptors in keratoconic cornea.

Abstract Purpose: To measure the expression level and pattern of neurotrophic factors and their receptors in keratoconus (KC) cornea using quantitative RT-PCR (qPCR) and immunostaining. Materials and Methods: Twenty-one recipient corneal buttons after keratoplasty from KC cornea and four age-matched normal corneas were obtained. The 25 corneal tissues were divided into two pieces; one fragment of each sample was used for immunostaining whereas the other fragment was used for qPCR. Using primary antibodies and specific qPCR primer, immunostaining and qPCR were performed to analyze the expression level of the neurotrophic factors and receptors. Results: Nerve growth factor and its receptors (TrkA and p75NTR) were not expressed in the center of normal cornea. However, TrkA and the p75NTR were clearly expressed in a membrane bound staining pattern and the mRNA levels were significantly higher in KC (pu2009<u20090.001). The mRNA expression of brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF) and neurotrophin (NT)-4 mRNA was also elevated in KC (pu2009<u20090.001). BDNF was expressed in epithelium of normal cornea. However, in KC, its expression was found to be extending into the anterior stromal layer. CNTF was hardly expressed in normal cornea. In KC, the entire epithelium expressed CNTF, especially in perinuclear area. NT-4 was expressed throughout the epithelium and stroma in KC. Conclusion: The change in expression of neurotrophic factors in KC may suggest that these factors play an important role in the pathogenesis of KC and serve as new markers for the progression of KC.

Factors affecting near vision after monofocal intraocular lens implantation.

PURPOSEnTo identify factors that influence near vision after monofocal intraocular lens (IOL) implantation for distance vision.nnnMETHODSnA retrospective review was conducted of patients who underwent cataract surgery with monofocal IOL implantation from October 2009 to April 2010 at Samsung Medical Center. Eyes were classified as having good (⩾ J4) or poor (< J4) near vision. Factors analyzed included age, sex, intraocular lens (IOL) movement, axial length, pupil size, degree and type of astigmatism, IOL type, total aberration, and higher-order aberrations. Binary logistic regression and odds ratios with 95% confidence intervals were determined.nnnRESULTSnThis retrospective study involved 84 eyes of 84 patients. Thirty-four eyes were classified as having good near vision and 50 eyes as having poor near vision. All groups had a postoperative uncorrected visual acuity greater than 0.2 logMAR (Snellen 20/32) and a refractive error within ± 0.5 diopter of spherical equivalent. Pupil size and axial length were inversely associated with good near vision (P = .034 and .039, respectively). A pupil size smaller than 2.6 mm and an axial length less than 23.0 mm resulted in better near vision than larger measurements after monofocal IOL implantation for distant target.nnnCONCLUSIONSnAmong the factors analyzed, small pupil size and short axial length predicted good near vision after phacoemulsification and monofocal IOL implantation.

Effect of Suturing on Iatrogenic-Keratectasia after Laser in situ Keratomileusis

PURPOSE: To evaluate the influence of corneal suturing on the clinical course of iatrogenic keratectasia after laser in situ keratomileusis (LASIK), in order to improve quality of vision and to avoid progressive deterioration of visual acuity. METHODS: Three patients (four eyes) who had a perforation during LASIK or became keratectatic after LASIK received corneal suturing with 10-0 nylon immediately or up to 11 days after LASIK. Sutures were left in place for 1 to 4 months. Patients were followed for 20 to 23 months after suturing. RESULTS: All eyes had a significant improvement in uncorrected and best spectacle-corrected visual acuity after suturing. The improvements in visual acuity for all patients remained unchanged after suture removal. In patient 1, keratectatic changes were not detected in the sutured eye although they were detected in the contralateral unsutured eye. In patient 2, both eyes were sutured, one immediately and the other 11 days after LASIK; no keratectatic changes were noted in either eye. Slight progression of corneal protrusion was observed in patient 3, who had corneal suturing after development of prominent keratectasia 2 weeks after LASIK. This eye showed stable but moderate keratectatic change 9 months after suture removal. CONCLUSIONS: Flap suturing in patients during the course of keratectasia after LASIK improved both aided and unaided visual acuity. Prompt suturing seemed to provide a means of preventive management for iatrogenic keratectasia in anticipation of keratoplasty.

Mutation Analysis of the TGFBI Gene in Consecutive Korean Patients With Corneal Dystrophies

Background Mutations in the transforming growth factor β-induced gene (TGFBI) are major causes of genetic corneal dystrophies (CDs), which can be grouped into TGFBI CDs. Although a few studies have reported the clinical and genetic features of Korean patients with TGFBI CD, no data are available regarding the frequency and spectrum of TGFBI mutations in a consecutive series of Korean patients with clinically diagnosed CDs. Methods Patients with any type of CD, who underwent both ophthalmologic examination and TGFBI gene analysis by Sanger sequencing at a tertiary care hospital in Seoul, Korea from 2006 to 2013, were enrolled in this study. Results Among a total of 89 patients, 77 (86.5%) were diagnosed as having clinical TGFBI CD. Seventy-three out of 74 patients (98.6%) with granular CD type 2 (GCD2), had the p.R124H mutation. Of particular note, one patient with rapidly progressive CD had the p.R124H mutation as well as a novel nonsense variant with unknown clinical significance (p.A179*). In three patients with lattice CD type 1 (LCD1), one known mutation (p.R124C) and two novel variants (p.L569Q and p.T621P) in the TGFBI gene were identified. Conclusions This study provides epidemiological insight into CDs in a Korean population and reaffirms that GCD2 is the most common TGFBI CD phenotype and that p.R124H is the only mutation identified in patients with GCD2. In addition, we broaden the spectrum of TGFBI mutations by identifying two novel missense variants in patients with LCD1.