Charles Q. Yu

Vascular endothelial growth factor mediates corneal nerve repair

PURPOSE To examine the expression of vascular endothelial growth factor (VEGF) and its receptors in the cornea and the trigeminal ganglion and to characterize the role of VEGF in mediating corneal nerve repair. METHODS Regeneration of the corneal subbasal nerve plexus after epithelial debridement was measured. The expression of VEGF and its receptors was examined in the trigeminal ganglia and in the cornea by RT-PCR, immunohistochemistry, and Western blotting. VEGF-mediated nerve growth was measured in a trigeminal ganglia explant assay. Anti-VEGF neutralizing antibody was used to examine the VEGF-dependent growth of neurons in vitro and regeneration of the corneal nerves in vivo. RESULTS After two distinct patterns of nerve regeneration, the subbasal nerves recovered to 65% of the preinjury density after 28 days. RT-PCR demonstrated gene expression of VEGF and VEGF receptors in the trigeminal ganglia. Immunohistochemistry showed staining for VEGF and its receptors in the trigeminal ganglia and for VEGFR1, VEGFR2, and neuropilin (NRP)-1 in the cornea. Western blot confirmed these results. In vitro, VEGF promoted the growth of explanted trigeminal ganglia by 91%. Blockage of VEGF signaling with anti-VEGF antibody reduced the growth of cultured neurons by 17% and the regeneration of subbasal neurons by 23%. CONCLUSIONS In addition to providing new information on the regeneration of murine corneal nerves, this study presents evidence that VEGF signaling influences the repair of corneal nerves by demonstrating that VEGF and VEGF receptors are present in the trigeminal ganglia and that abrogation of VEGF signaling reduces nerve growth in vitro and in vivo.

Prevention of postcataract endophthalmitis: evidence-based medicine.

Purpose of review To provide a summary of current peer-reviewed publications on the methods of prophylaxis against postcataract endophthalmitis. Recent findings Preoperative application of povidone–iodine remains the standard protocol for the prevention of postoperative endophthalmitis. More recent evidence suggests that intracameral cefuroxime administered at the conclusion of surgery significantly reduces the risk of endophthalmitis. However, its clinical use has been limited because of a lack of commercially available antibiotic indicated for intraocular injection. Although topical antibiotic application continues to be a controversial topic with respect to the types of antibiotic prescribed and dosage, most ophthalmologists do prescribe an antibiotic for the perioperative period. Resistance against antibiotics, including the very popular classes of fluoroquinolones, is rising. Most notably, methicillin resistance continues to increase over time. Summary Prevention of postcataract endophthalmitis remains a difficult topic to study given the low incidence. In addition to appropriate wound construction, a combination of povidone–iodine and antibiotics provide a reasonable approach in reducing the risk of this rare but serious infection.

Comparison of 2 wavefront-guided excimer lasers for myopic laser in situ keratomileusis: One-year results

Purpose To compare laser in situ keratomileusis (LASIK) outcomes between 2 wavefront‐guided excimer laser systems in the treatment of myopia. Setting University eye clinic, Palo Alto, California, USA. Design Prospective comparative case series. Methods One eye of patients was treated with the Allegretto Wave Eye‐Q system (small‐spot scanning laser) and the fellow eye with the Visx Star Customvue S4 IR system (variable‐spot scanning laser). Evaluations included measurement of uncorrected visual acuity, corrected visual acuity, and wavefront aberrometry. Results One hundred eyes (50 patients) were treated. The mean preoperative spherical equivalent (SE) refraction was −3.89 diopters (D) ± 1.67 (SD) and −4.18 ± 1.73 D in the small‐spot scanning laser group and variable‐spot scanning laser group, respectively. There were no significant differences in preoperative higher‐order aberrations (HOAs) between the groups. Twelve months postoperatively, all eyes in the small‐spot scanning laser group and 92% in the variable‐spot scanning laser group were within ±0.50 D of the intended correction (P = .04). At that time, the small‐spot scanning laser group had significantly less spherical aberration (0.12 versus 0.15) (P = .04) and significantly less mean total higher‐order root mean square (0.33 &mgr;m versus 0.40 &mgr;m) (P = .01). Subjectively, patients reported that the clarity of night and day vision was significantly better in the eye treated with the small‐spot scanning laser. Conclusions The predictability and self‐reported clarity of vision of wavefront‐guided LASIK were better with the small‐spot scanning laser. Eyes treated with the small‐spot scanning laser had significantly fewer HOAs. Financial Disclosure Dr. Manche is a consultant to Equity in Calhoun Vision, Inc., Krypton Vision, Inc., Refresh Innovations, Inc., Seros Medical, LLC, Veralas, Inc., Best Doctors, Gerson Lehrman, Guidepoint Global. Dr. Yu has no financial or proprietary interest in any material or method mentioned.

Biocompatibility of poly(ethylene glycol) and poly(acrylic acid) interpenetrating network hydrogel by intrastromal implantation in rabbit cornea

We evaluated the biocompatibility of a poly(ethylene glycol) and poly(acrylic acid) (PEG/PAA) interpenetrating network hydrogel designed for artificial cornea in a rabbit model. PEG/PAA hydrogel measuring 6 mm in diameter was implanted in the corneal stroma of twelve rabbits. Stromal flaps were created with a microkeratome. Randomly, six rabbits were assigned to bear the implant for 2 months, two rabbits for 6 months, two rabbits for 9 months, one rabbit for 12 months, and one rabbit for 16 months. Rabbits were evaluated monthly. After the assigned period, eyes were enucleated, and corneas were processed for histology and immunohistochemistry. There were clear corneas in three of six rabbits that had implantation of hydrogel for 2 months. In the six rabbits with implant for 6 months or longer, the corneas remained clear in four. There was a high rate of epithelial defect and corneal thinning in these six rabbits. One planned 9-month rabbit developed extrusion of implant at 4 months. The cornea remained clear in the 16-month rabbit but histology revealed epithelial in-growth. Intrastromal implantation of PEG/PAA resulted in a high rate of long-term complications.

Comparison of 2 femtosecond lasers for flap creation in myopic laser in situ keratomileusis: One-year results

Purpose To compare laser in situ keratomileusis (LASIK) outcomes between 2 femtosecond lasers for flap creation in the treatment of myopia up to 1 year. Setting University eye clinic. Design Prospective randomized eye‐to‐eye study. Methods Consecutive myopic patients were treated with wavefront‐guided LASIK. One eye had a flap created by the Intralase FS 60 kHz femtosecond laser, and the fellow eye was treated with the Intralase iFS 150 kHz femtosecond laser. Eyes were randomized according to ocular dominance. Evaluations included measurement of uncorrected distance visual acuity (UDVA), corrected distance visual acuity, contrast sensitivity and wavefront aberrometry. Results The study enrolled 122 eyes of 61 patients. The mean preoperative spherical equivalent refraction was −4.62 diopters (D) ± 2.32 (SD) and −4.66 ± 2.30 D in the 150 kHz group and 60 kHz group, respectively. Patients preferred the 150 kHz laser to the 60 kHz laser intraoperatively (52.5% versus 26.2%) (P = .005). One week postoperatively, UDVA was 20/16 or better in 85.2% in the 150 kHz group and 70.5% in the 60 kHz group; the difference was statistically significant (P < .05). At 12 months, there were no significant differences in refractive outcomes or higher‐order aberrations between the 2 groups. Conclusions Flap creation with the 150 kHz system and the 60 kHz system resulted in excellent LASIK outcomes. Intraoperatively, patients preferred the 150 kHz system, which yielded better UDVA in the early postoperative period. There were no significant differences at 1 year between the 2 laser systems. Financial Disclosure Proprietary or commercial disclosures are listed after the references.

A comparison of LASIK flap thickness and morphology between the Intralase 60- and 150-kHz femtosecond lasers.

PURPOSE To prospectively compare the achieved thickness and consistency of LASIK flaps created with a 60- and 150-kHz femtosecond laser. METHODS One hundred twenty eyes of 60 patients with myopia were treated with LASIK. One eye had flap created by the Intralase FS 60-kHz femtosecond laser (Abbott Medical Optics, Abbott Park, IL) and the fellow eye was treated with the IntraLase iFS 150-kHz femtosecond laser (Abbott Medical Optics). Eyes were randomized according to ocular dominance. Flap morphology and measurements were taken with anterior segment optical coherence tomography (AS-OCT) at the 1-month postoperative visit. RESULTS AS-OCT showed similar regular planar morphologies in both groups. The mean thickness of the flaps in the FS 60 group was significantly higher than that of the iFS 150 group (105.4 ± 3.9 μm vs 103.9 ± 4.8 μm, P = .009). The mean deviation from targeted flap thickness was not significantly different between the two groups. CONCLUSIONS The Intralase iFS 150-kHz femtosecond laser creates flaps of similar thickness and uniformity to the Intralase FS 60-kHz femtosecond laser.

Subretinal fluid is common in experimental non-arteritic anterior ischemic optic neuropathy

PurposeAnterior ischemic optic neuropathy (AION) is an important cause of acute vision loss for which several animal models exist. It has been associated with subretinal fluid in a previous study on patients but not yet so in animal models.Patients and MethodsA patient presented with acute non-arteritic AION (NAION) and underwent ophthalmic evaluation and testing including fluorescein angiography and spectral-domain optical coherence tomography (SD-OCT). On the basis of the patient’s findings, we used SD-OCT circular and volume scans to analyze retinal changes in a murine model of NAION.ResultsOne week after left eye vision loss, the patient had clinical and imaging findings consistent with NAION. On SD-OCT, there was prominent peripapillary retinal thickening consistent with intra-retinal edema and sub-foveolar fluid. Inspired by the findings in human AION, we looked for similar changes in murine NAION using SD-OCT. The circular scan did not adequately detect the presence of subretinal fluid. Using the 25-line scan, which covered a larger part of the posterior pole, we found that 100% of murine AION resulted in subretinal fluid at day 1. The subretinal fluid resolved by week 1.ConclusionThis study detailed a case of clinical NAION associated with intra-retinal and subretinal fluid. We also found that subretinal fluid was common in murine photochemical thrombosis model of AION and could be found far away from the optic disc.

Subjective Quality of Vision After Myopic LASIK: Prospective 1-Year Comparison of Two Wavefront-Guided Excimer Lasers.

PURPOSE To compare subjective quality of vision between two wavefront-guided lasers in the treatment of myopia up to 1 year postoperatively. METHODS In this prospective randomized study, 100 eyes of 50 patients were treated with wavefront-guided LASIK. One eye was treated with the WaveLight Allegretto Wave Eye-Q 400-Hz excimer laser (Alcon Laboratories, Inc., Hünenberg, Switzerland) and the other was treated with the VISX Star S4 IR CustomVue excimer laser (Abbott Medical Optics, Santa Ana, CA). Patients completed a questionnaire assessing quality of vision and visual symptoms preoperatively and at postoperative months 1, 3, 6, and 12. RESULTS The Allegretto system demonstrated non-statistically significant superiority in several subjective parameters as early as 1 month after surgery. At 12 months, there was better clarity during the day (P = .001) in the Allegretto group. Subgroup analyses were performed on eyes with preoperative higher order aberrations of 0.3 µm or less and in patients with preoperative higher order aberrations greater than 0.3 µm. In subgroup analysis, there were no differences between the two systems in eyes with low higher order aberrations or high higher order aberrations. Patients did not express any preference for one system over the other when surveyed at 1 year postoperatively. CONCLUSIONS One year after surgery, there were no differences in self-reported quality of vision outcomes with the exception of better clarity of vision during the day in the eyes treated with the Allegretto system. Patients did not express any preference for one treatment modality over the other.

Successful DMEK after intraoperative graft inversion

Purpose: Hardiness of a Descemet membrane endothelial keratoplasty (DMEK) graft is not well established. The aim of this study was to report a case of graft survival after intraoperative inversion. Methods: We describe a case of a 76-year-old man with Fuchs corneal dystrophy who underwent DMEK in the left eye. After deployment of the graft and a 15-minute sulfur hexafluoride gas fill, the graft was noted to be inverted. The graft was then reoriented and properly positioned. Results: Because of progressive graft detachment, rebubble was required at 2 weeks after surgery. At 2 months after surgery, the graft was clear and fully adherent. Specular microscopy revealed 27.9% endothelial cell loss of the donor cornea. Conclusions: Despite intraoperative inversion, this DMEK graft remained viable without excessive endothelial cell loss.

Day 1 wavefront aberrometry for prediction of refractive outcomes at year 1 in myopic LASIK.

PURPOSE To determine amount of change in wavefront aberrometric measurements from 1 day to 1 year after myopic LASIK. METHODS One hundred five eyes of 105 patients underwent wavefront-guided LASIK. Objective wavefront aberrometric refractions were recorded preoperatively, at postoperative day 1, and at postoperative year 1. Subjective manifest refractions were also collected at postoperative year 1. RESULTS When comparing objective wavefront aberrometric refractions at postoperative year 1 to postoperative day 1, there was a mean 0.33 diopter spherical equivalent myopic shift. There was no significant difference in the number of eyes within 1.00 diopter of emmetropia spherical equivalent measured by wavefront aberrometric refraction at postoperative day 1 or year 1. There was a correlation of R(2) = 0.14 between degree of preoperative myopia and myopic shift. Higher-order aberrations were overall not increased at day 1 but increased significantly by year 1. Objective aberrometric refractions at postoperative day 1 can be useful in prediction of long-term refractive outcomes. CONCLUSIONS There is a small myopic shift and an increase in higher-order aberrations when comparing wavefront aberrometry results at postoperative day 1 with those at postoperative 1 year.