Roberto Pineda

Topical Bevacizumab in the Treatment of Corneal Neovascularization Results of a Prospective, Open-Label, Noncomparative Study

OBJECTIVE To study the safety and efficacy of topical bevacizumab in the treatment of corneal neovascularization (NV). DESIGN In a prospective, open-label, noncomparative study, 10 eyes from 10 patients with stable corneal NV were treated with topical bevacizumab, 1.0%, for 3 weeks and followed up for up to 24 weeks. MAIN OUTCOME MEASURES The primary safety variables were the occurrence of ocular and systemic adverse events throughout the course of the study. The primary efficacy variables were neovascular area, the area of the corneal vessels themselves; vessel caliber, the mean diameter of the corneal vessels; and invasion area, the fraction of the total corneal area covered by the vessels. RESULTS From baseline visit to the last follow-up visit, mean reductions were 47.1% (standard deviation [SD], 36.7%) for neovascular area, 54.1% (SD, 28.1%) for vessel caliber, and 12.2% (SD, 42.0%) for invasion area. The decreases in neovascular area and vessel caliber were statistically significant (P= .001 and P< .001, respectively). However, changes in invasion area did not achieve statistical significance (P= .19). Visual acuity and central corneal thickness showed no significant changes. Topical bevacizumab was well tolerated with no adverse events. CONCLUSIONS Short-term topical bevacizumab therapy reduces the severity of corneal NV without local or systemic adverse effects. APPLICATION TO CLINICAL PRACTICE Topical bevacizumab provides an alternative therapy in the treatment of stable corneal NV. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00559936.

Brillouin Optical Microscopy for Corneal Biomechanics

PURPOSE The mechanical properties of corneal tissue are linked to prevalent ocular diseases and therapeutic procedures. Brillouin microscopy is a novel optical technology that enables three-dimensional mechanical imaging. In this study, the feasibility of this noncontact technique was tested for in situ quantitative assessment of the biomechanical properties of the cornea. METHODS Brillouin light-scattering involves a spectral shift proportional to the longitudinal modulus of elasticity of the tissue. A 532-nm single-frequency laser and a custom-developed ultrahigh-resolution spectrometer were used to measure the Brillouin frequency. Confocal scanning was used to perform Brillouin elasticity imaging of the corneas of whole bovine eyes. The longitudinal modulus of the bovine corneas was compared before and after riboflavin corneal collagen photo-cross-linking. The Brillouin measurements were then compared with conventional stress-strain mechanical test results. RESULTS High-resolution Brillouin images of the cornea were obtained, revealing a striking depth-dependent variation of the elastic modulus across the cornea. Along the central axis, the Brillouin frequency shift varied gradually from 8.2 GHz in the epithelium to 7.5 GHz near the endothelium. The coefficients of the down slope were measured to be approximately 1.09, 0.32, and 2.94 GHz/mm in the anterior, posterior, and innermost stroma, respectively. On riboflavin collagen cross-linking, marked changes in the axial Brillouin profiles (P < 0.001) were noted before and after cross-linking. CONCLUSIONS Brillouin imaging can assess the biomechanical properties of cornea in situ with high spatial resolution. This novel technique has the potential for use in clinical diagnostics and treatment monitoring.

Brillouin Microscopy of Collagen Crosslinking: Noncontact Depth-Dependent Analysis of Corneal Elastic Modulus

PURPOSE Corneal collagen crosslinking (CXL) is designed to halt the progression of keratoconus and corneal ectasia by inducing corneal stiffening. However, it currently is difficult to monitor and evaluate CXL outcome objectively due to the lack of suitable methods to characterize corneal mechanical properties. We validated noncontact Brillouin microscopy to quantify corneal mechanical properties before and after CXL. METHODS CXL was performed on fresh porcine eyes using various presoaking times and light doses, with or without epithelial debridement. From Brillouin maps of corneal elastic modulus, stiffness and average modulus of anterior, middle, and posterior stroma were analyzed. Corneal stiffening index (CSI) was introduced as a metric to compare the mechanical efficacy of a given CXL protocol with respect to the standard protocol (30-minute riboflavin presoak, 3 mW/cm² ultraviolet illumination for 30 minutes). RESULTS Brillouin corneal stiffness increased significantly (P < 0.001) by epi-off and epi-on CXL. The increase of Brillouin modulus was depth-dependent, indicating that anterior stromal stiffening contributes the most to mechanical outcome. The increase of anterior Brillouin modulus was linearly proportional to the light dose (R² > 0.98). Compared to the standard epi-off procedure, a typical epi-on procedure resulted in a third of stiffness increase in porcine corneas (CSI = 33). CONCLUSIONS Brillouin microscopy allowed imaging and quantifying CXL-induced mechanical changes without contact in a depth-dependent manner at high spatial resolution. This technique may be useful to evaluate the mechanical outcomes of CXL procedures, to compare different crosslinking agents, and for real-time monitoring of CXL in clinical and experimental settings.

Alzheimer's Disease Amyloid-β Links Lens and Brain Pathology in Down Syndrome

Down syndrome (DS, trisomy 21) is the most common chromosomal disorder and the leading genetic cause of intellectual disability in humans. In DS, triplication of chromosome 21 invariably includes the APP gene (21q21) encoding the Alzheimers disease (AD) amyloid precursor protein (APP). Triplication of the APP gene accelerates APP expression leading to cerebral accumulation of APP-derived amyloid-β peptides (Aβ), early-onset AD neuropathology, and age-dependent cognitive sequelae. The DS phenotype complex also includes distinctive early-onset cerulean cataracts of unknown etiology. Previously, we reported increased Aβ accumulation, co-localizing amyloid pathology, and disease-linked supranuclear cataracts in the ocular lenses of subjects with AD. Here, we investigate the hypothesis that related AD-linked Aβ pathology underlies the distinctive lens phenotype associated with DS. Ophthalmological examinations of DS subjects were correlated with phenotypic, histochemical, and biochemical analyses of lenses obtained from DS, AD, and normal control subjects. Evaluation of DS lenses revealed a characteristic pattern of supranuclear opacification accompanied by accelerated supranuclear Aβ accumulation, co-localizing amyloid pathology, and fiber cell cytoplasmic Aβ aggregates (∼5 to 50 nm) identical to the lens pathology identified in AD. Peptide sequencing, immunoblot analysis, and ELISA confirmed the identity and increased accumulation of Aβ in DS lenses. Incubation of synthetic Aβ with human lens protein promoted protein aggregation, amyloid formation, and light scattering that recapitulated the molecular pathology and clinical features observed in DS lenses. These results establish the genetic etiology of the distinctive lens phenotype in DS and identify the molecular origin and pathogenic mechanism by which lens pathology is expressed in this common chromosomal disorder. Moreover, these findings confirm increased Aβ accumulation as a key pathogenic determinant linking lens and brain pathology in both DS and AD.

Diffuse lamellar keratitis: Incidence, associations, outcomes, and a new classification system

Purpose: To evaluate the incidence, associations, and visual outcomes in patients with diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK). Setting: University‐based refractive surgery center, Boston, Massachusetts, USA. Methods: This retrospective review comprised 2711 eyes that had LASIK between September 1996 and September 1999. All eyes that developed DLK after LASIK were included. They were divided into type I DLK (center sparing) or type II DLK (center involved) and then subdivided into A (sporadic—DLK not diagnosed in other patients treated on the same day) or B (cluster—other patients identified with DLK). Type IA corresponded to center sparing, sporadic; type IB, center sparing, cluster; type IIA, center involved, sporadic; and type IIB, center involved, cluster. The main outcome measures were incidence of DLK after LASIK, time to diagnosis, time to resolution, and changes in best spectacle‐corrected visual acuity (BSCVA). Unpaired t tests were used for statistical analyses. Results: Thirty‐six eyes (1.3%) developed DLK. Type I occurred in 58.3% of cases (type IA, n = 18; type IB, n = 3) and type II, in 41.7% (type IIA, n = 10; type IIB, n = 5). The mean time to diagnosis was not statistically significantly different between type I (1.8 days) and type II (1.1 days). Fourteen eyes (38.9%) developed DLK after an epithelial defect, representing an odds ratio of 13 times. The association with an epithelial defect was statistically significantly greater with type I (11/21 eyes, 52.4%) than with type II (3/15 eyes, 20.0%; P = .05). The mean time to resolution was 3.5 days in type I (type IA = 3.6 days; type IB = 2.7 days). This was significantly shorter than in type II, which had a mean time to resolution of 12.1 days (type IIA = 9.3 days; type IIB = 10.2 days) (P = .001). Loss of 2 or more lines of BSCVA occurred in 2 of 5 patients with type IIB and in no patients with types IA, IB, or IIA. Conclusions: Epithelial defects after LASIK increased the risk of DLK occurrence, especially type I. Type II DLK was associated with a prolonged time to resolution and carried a significantly higher risk of BSCVA loss than type I.

A Study of Topical Nonsteroidal Anti-inflammatory Drops and No Pressure Patching in the Treatment of Corneal Abrasions

OBJECTIVE To evaluate the effectiveness of an ophthalmic nonsteroidal anti-inflammatory drug (NSAID) in the treatment of noninfected, non-contact lens-related, traumatic corneal abrasions and no pressure patch. DESIGN A single-center, randomized, double-masked, placebo-controlled study. PARTICIPANTS One hundred patients with noninfected, non-contact lens-related, traumatic or foreign body removal-related corneal abrasions less than 36 hours in duration. INTERVENTION All patients received a cycloplegic drop and erythromycin or polymyxin B (Polysporin Ophthalmic Ointment, Burroughs Wellcome, Research Triangle Park, NC). Patients were then randomized to receive either ketorolac tromethamine 0.5% ophthalmic solution or control vehicle drops. MAIN OUTCOME MEASURES The main outcome measures were six subjective symptoms monitored daily, evaluation of corneal abrasion, and determination of adverse events. Long-term complications were determined 3 to 8 months after randomization. RESULTS Twelve patients were excluded from the study. One day after randomization, patients receiving ketorolac tromethamine 0.5% ophthalmic solution noted significantly decreased levels of pain (P < 0.002), photophobia (P < 0.009), and foreign body sensation (P < 0.003) as compared with the control vehicle group. In addition, the time to resumption of normal activities was shorter in the group who received ketorolac tromethamine 0.5% ophthalmic solution (P < 0.001). There was no statistical difference in the amount of tearing, healing time, acuity changes, or complication rates between the two groups. CONCLUSIONS Ketorolac tromethamine 0.5% ophthalmic solution provides increased patient comfort without clinical adverse effects when used as adjunctive therapy in the treatment of noninfected, non-contact lens-related, traumatic corneal abrasions.

Biomechanical characterization of keratoconus corneas ex vivo with Brillouin microscopy.

PURPOSE Loss of corneal strength is a central feature of keratoconus progression. However, it is currently difficult to measure corneal mechanical changes noninvasively. The objective of this study is to evaluate if Brillouin optical microscopy can differentiate the mechanical properties of keratoconic corneas versus healthy corneas ex vivo. METHODS We obtained eight tissue samples from healthy donor corneas used in Descemets stripping endothelial keratoplasty (DSEK) and 10 advanced keratoconic corneas from patients undergoing deep anterior lamellar keratoplasty (DALK). Within 2 hours after surgery, a confocal Brillouin microscope using a monochromatic laser at 532 nm was used to map the Brillouin frequency shifts of the corneas. RESULTS The mean Brillouin shift in the anterior 200 μm of the keratoconic corneas at the cone was measured to be 7.99 ± 0.10 GHz, significantly lower than 8.17 ± 0.06 GHz of the healthy corneas (P < 0.001). The Brillouin shift in the keratoconic corneas decreased with depth from the anterior toward posterior regions with a steeper slope than in the healthy corneas (P < 0.001). Within keratoconic corneas, the Brillouin shift in regions away from the apex of the cone was significantly higher than within the cone region (P < 0.001). CONCLUSIONS Brillouin measurements revealed notable differences between healthy and keratoconic corneas. Importantly, Brillouin imaging showed that the mechanical loss is primarily concentrated within the area of the keratoconic cone. Outside the cone, the Brillouin shift was comparable with that of healthy corneas. The results demonstrate the potential of Brillouin microscopy for diagnosis and treatment monitoring of keratoconus.

Phacoemulsification and thermal wound injury

The technique of lens nucleus phacoemulsification has revolutionized cataract surgery. However, the production of ultrasound energy is associated with heat generation that can result in damage to ocular tissue, in particular the corneoscleral wound site. Thermal damage to the corneoscleral wound site may result in difficulty with wound closure and consequent risk of wound leakage, as well as damage to the adjacent corneal stroma and endothelium, fistula formation, and the induction of high degrees of post-operative astigmatism. The loss of adequate flow of irrigation fluid around the phacoemulsification tip is the key factor in the development of phacoemulsification-induced thermal injury. Use of excessive ultrasound power and production of excessive frictional forces generated by contact of the vibrating phacoemulsification needle with the irrigation sleeve are also factors involved. In the event of a “phacoburn,” a specialized “gape suture” may help minimize surgically-induced astigmatism. The degree of induced astigmatism tends to wane over time; astigmatic keratotomy is an option in the setting of high degrees of residual astigmatism.

Ocular Changes in the Mucopolysaccharidoses after Bone Marrow Transplantation: A Preliminary Report

Metabolic correction and physiologic response were evaluated after bone marrow transplantation in mucopolysaccharidosis. Eleven patients were prospectively evaluated to determine the effect of bone marrow transplantation on the progressive ocular manifestations of these disorders. Follow-up of 0.6 to 2.8 years after successful donor stem cell engraftment showed that some patients had slow clearing of the corneal clouding, reduction of intracytoplasmic inclusions in the conjunctiva, resolution of optic nerve edema, and stabilized or improved retinal function as determined by electroretinography. These preliminary results suggest that early bone marrow transplantation may alter some of the progressive ophthalmic characteristics of the mucopolysaccharidoses. Long-term follow-up is necessary to determine if these early alterations in the ocular features are predictive of a prolonged functional improvement in the visual status.

Corneal ulceration and perforation with ketorolac tromethamine (Acular) use after PRK.

To report a case of corneal ulceration and perforation after PRK connected with high doses of ketorolac tromethamine (Acular®). Methods: A 31-year-old man presented 5 days after PRK in the left eye with corneal ulceration and perforation requiring penetrating keratoplasty. The patient admitted to using Acular® every hour, ciprofloxocin every hour, and prednisolone acetate 1% QID postoperatively. Results: Laboratory tests, including corneal cultures, were normal. A diagnosis of corneal ulceration secondary to incorrect use of high-dose ketorolac tromethamine was made. Conclusion: Judicious patient counseling is recommended when using topical NSAIDs in the setting of PRK.