Anna Maria Demetriades

Combined phacoemulsification, intraocular lens implantation, and vitrectomy for eyes with coexisting cataract and vitreoretinal pathology ☆

PURPOSE To report the preoperative, intraoperative, and postoperative outcomes of combining phacoemulsification and posterior chamber intraocular lens (IOL) implantation with pars plana vitrectomy in eyes with significant cataract and coexisting vitreoretinal pathology. DESIGN Retrospective, consecutive, interventional case series. METHODS Charts of patients undergoing combined procedures at the Wilmer Ophthalmologic Institute between March 1995 and May 2000 were reviewed. RESULTS In all, 122 eyes of 111 patients were identified. Patient ages ranged from 27 to 89 years (mean 65). Forty-three eyes had diabetic retinopathy; 11 had undergone vitrectomy previously. Macular pathology (hole, membrane, choridal neovascularization) was present in 69 eyes. The most common indications for surgery were diabetic vitreous hemorrhage, macular hole, epiretinal membrane, and retinal detachment. In all cases, phacoemulsification and IOL implantation were performed before vitreoretinal surgery. Preoperative vision ranged from 20/30 to light perception and postoperative vision ranged from 20/20 to no light perception. In 105 patients vision improved, in 7 there was no change, and in 10 vision decreased. Postoperative complications included opacification of the posterior capsule, increased intraocular pressure, corneal epithelial defects, vitreous hemorrhage, retinal detachment and iris capture by the IOL. CONCLUSIONS Combined surgery is a reasonable alternative in selected patients. Techniques that may simplify surgery and reduce complications include: careful, limited, curvilinear capsulorhexis; in-the-bag placement of IOLs; use of IOLs with larger optics; suturing of cataract wounds before vitrectomy; use of miotics and avoidance of long-acting dilating drops in patients with intravitreal gas; and use of wide-field viewing systems.

Periocular injection of an adenoviral vector encoding pigment epithelium-derived factor inhibits choroidal neovascularization

Gene transfer provides an exciting new approach for the treatment of retinal and choroidal diseases. Two areas of concern are the potential for vector-related toxicity and uncertainties associated with prolonged transgene expression. One way to address these concerns for transfer of genes encoding secreted proteins is to transduce cells on the outside of the eye, provided the gene product can gain access to the eye and have the desired effect. In this study, we investigated the feasibility of this approach. Periocular injection of an adenoviral vector encoding β-galactosidase (AdLacZ.10) resulted in LacZ-stained cells throughout the orbit and around the eye. Compared to periocular injection of 5 × 109 particles of control vector, periocular injection of 5 × 109 or 1 × 109 particles of an adenoviral vector expressing pigment epithelium-derived factor (PEDF) regulated by a CMV promoter (AdPEDF.11) resulted in significantly elevated intraocular levels of PEDF and suppression of choroidal neovascularization. Periocularly injected recombinant PEDF was also found to diffuse through the sclera into the eye. Although similar experiments are needed in an animal with a human-sized eye, these data suggest that periocular gene transfer deserves consideration for the treatment of choroidal diseases.

Periocular gene transfer of sFlt-1 suppresses ocular neovascularization and vascular endothelial growth factor-induced breakdown of the blood-retinal barrier

Vascular endothelial growth factor (VEGF) is a critical stimulus for both retinal and choroidal neovascularization, and for diabetic macular edema. We used mouse models for these diseases to explore the potential of gene transfer of soluble VEGF receptor-1 (sFlt-1) as a treatment. Intravitreous or periocular injection of an adenoviral vector encoding sFlt-1 (AdsFlt-1.10) markedly suppressed choroidal neovascularization at rupture sites in Bruchs membrane. Periocular injection of AdsFlt-1.10 also caused significant reduction in VEGF-induced breakdown of the blood-retinal barrier, but failed to significantly inhibit ischemia-induced retinal neovascularization. Periocular delivery of an adenoviral vector encoding pigment epithelium-derived factor (PEDF), another secreted protein, resulted in high levels of PEDF in the retinal pigmented epithelium and choroid, but not in the retina. This may explain why periocular injection of AdsFlt-1.10 inhibited choroidal, but not retinal neovascularization. Periocular delivery offers potential advantages over other routes of delivery and the demonstration that sFlt-1 enters the eye from the periocular space in sufficient levels to achieve efficacy in treating choroidal neovascularization and retinal vascular permeability is a novel finding that has important clinical implications. These data suggest that periocular gene transfer of sFlt-1 should be considered for treatment of choroidal neovascularization and diabetic macular edema.

Verge: A Novel Vascular Early Response Gene

Vascular endothelium forms a continuous, semipermeable barrier that regulates the transvascular movement of hormones, macromolecules, and other solutes. Here, we describe a novel immediate early gene that is expressed selectively in vascular endothelial cells, verge (vascular early response gene). Verge protein includes an N-terminal region of ∼70 amino acids with modest homology (∼30% identity) to Apolipoprotein L but is otherwise unique. Verge mRNA and protein are induced selectively in the endothelium of adult vasculature by electrical or chemical seizures. Verge expression appears to be responsive to local tissue conditions, because it is induced in the hemisphere ipsilateral to transient focal cerebral ischemia. In contrast to the transient expression in adult, Verge mRNA and protein are constitutively expressed at high levels in the endothelium of developing tissues (particularly heart) in association with angiogenesis. Verge mRNA is induced in cultured endothelial cells by defined growth factors and hypoxia. Verge protein is dramatically increased by cysteine proteinase inhibitors, suggesting rapid turnover, and is localized to focal regions near the periphery of the cells. Endothelial cell lines that stably express Verge form monolayers that show enhanced permeability in response to activation of protein kinase C by phorbol esters. This response is accompanied by reorganization of the actin cytoskeleton and the formation of paracellular gaps. These studies suggest that Verge functions as a dynamic regulator of endothelial cell signaling and vascular function.

Trans-scleral delivery of antiangiogenic proteins

PURPOSE In this study, we investigated the penetration of various proteins into the mouse eye after a periocular injection of the protein or an adenoviral vector (Ad) expressing the protein. METHODS At several time points after the injection, the retina, retinal pigmented epithelium/choroid, and sclera were dissected and enzyme-linked immunosorbent assays were performed. RESULTS After a periocular injection of AdsFlt-1.10, AdTGFbeta.10, or AdPEDF.11, choroidal levels of pigment epithelium-derived factor (PEDF) and transforming growth factor-beta (TGF-beta) were not significantly different from scleral levels, and choroidal levels of sFlt-1 (soluble Flt-1 or soluble VEGF receptor 1) were only moderately reduced from scleral levels, indicating that each of these proteins penetrate the sclera well. In contrast, retinal levels of each of the three proteins were low compared to choroidal levels, suggesting poor penetration into the retina. Levels of PEDF in the choroid peaked 2 h after a periocular injection of PEDF protein and returned to baseline between 6 and 24 h, and peak levels in the retina were 8.6% of peak choroidal levels. Levels of green fluorescent protein, a protein unlikely to have any binding sites in mouse tissues, peaked in the choroid 2 h after the periocular injection and were undetectable by 4 h, while peak levels in the retina were 64.3% of peak choroidal levels. CONCLUSIONS These data suggest that size and binding characteristics of proteins are likely to influence their ability to penetrate the eye from the periocular space, but in general, proteins as large as 50-75 kDa penetrate well into the choroid, but not into the retina. Periocular injections are feasible for the treatment of choroidal neovascularization with proteins or vectors that express them, but additional investigations are needed before they can be considered for treatment of retinal diseases.

Protein Transport to Choroid and Retina following Periocular Injection: Theoretical and Experimental Study

Ocular neovascularization is a major cause of blindness in several diseases including age-related macular degeneration (choroidal neovascularization) and diabetic retinopathy (retinal neovascularization). Antiangiogenic agents with clinically significant effects exist, but a key question remains: how to effectively deliver drugs to the site of neovascularization. Periocular delivery of drugs or proteins is less invasive and safer than intravitreous delivery, but little is known regarding how and to what extent agents access intraocular tissues after periocular injection. We present a computational model of drug or protein transport into the eye following periocular injection to quantify movement of macromolecules across the sclera of the mouse eye. We apply this model to the movement of green fluorescent protein (GFP) across the mouse eye and fit the results of in vivo experiments to find transport parameters. Using these parameters, the model gives the profile of interstitial GFP concentration across the sclera, choroid and retina. We compare this to predictions of transport following intravitreous injections. We then scale up the model to estimate the transport of GFP into the human choroid and retina; the thicker sclera decreases transscleral delivery. This is the first model of ocular drug delivery to explicitly account for transport properties of each eye layer.

Peripheral ulcerative keratitis after clear corneal cataract extraction

A previously healthy 80-year-old man had uneventful clear corneal cataract extraction. An extensive peripheral corneal infiltrate with overlying epithelial defect at the incision site was noted at the regular follow-up visit 1 week after surgery. Corneal cultures showed no evidence of infectious keratitis. A systemic evaluation uncovered early-stage, active rheumatoid arthritis. This case illustrates that peripheral ulcerative keratitis may occur with a small clear corneal incision and may be the presenting sign of a previously undiagnosed rheumatoid disease.

Mouse model of post-surgical breakdown of the blood-retinal barrier

Purpose. Post-surgical macular edema is an important clinical problem resulting from breakdown of the blood-retinal barrier (BRB) after surgery. This study was designed to develop a mouse model of post-surgical BRB breakdown. Methods. Two 25-gauge needles, one for infusion and one for aspiration, were inserted through the limbus and into the lens of one eye of adult male C57BL/6 mice. The anterior portion of the lens was aspirated and the fellow eye was untreated. At several time points after surgery, the integrity of the BRB was assessed quantitatively, using [3H]mannitol as a tracer, or qualitatively, using immunohistochemical staining for albumin. Results. Eyes with partial lens extraction had a significant increase in retinal vascular leakage one day after surgery, which persisted two and three days after surgery, but by five days, was not significantly different from controls. Immunohistochemical staining for albumin demonstrated that the breech in the barrier was sufficient to allow passage of a 60 kDa protein into the retina, and was localized predominantly to retinal vessels. Conclusions. Partial lens extraction in mice results in BRB breakdown (primarily the inner BRB) that is highly reproducible in the severity of leakage and its time course. This provides a valuable tool for investigation of the molecular pathogenesis and new treatment approaches for post-surgical breakdown of the BRB.

Intraglandular Injection of Botulinum Toxin A Reduces Tear Production in Rabbits

Purpose: To develop an animal model and investigate the dose-dependent effect of an intraglandular injection of botulinum toxin A (BTX-A) on tear production. Methods: In a volume of 0.1-ml, 0.625-, 1.25-, or 2.5-U BTX-A was injected transconjunctivally in the superolateral lobe of the lacrimal gland of adult New Zealand white female rabbits. In the contralateral lacrimal gland, 0.1 ml of 0.9% sodium chloride was injected. Prior to injection and at 1-week postinjection, photographs were taken to evaluate pre- and postoperative eyelid position. Fluorescein and Rose Bengal stain were used to evaluate the corneal surface, and Schirmer test was used to assess tear production. Results: Glands injected with the intermediate (1.25 U) and the highest (2.5 U) doses of BTX-A displayed a statistically significant decrease in tear production (p = 0.002 and 0.007, respectively) compared with the contralateral saline-injected glands at 1 week. No corneal pathologic factors from excessive dryness were observed following the injection. While postinjection ptosis was observed (p = 0.025), no difference was seen between BTX-A and saline-injected eyes. Conclusions: In rabbits, intraglandular injection of BTX-A resulted in decreased tear production at 1 week. No additional reduction in tear production was seen with a BTX-A dose greater than 1.25 U, suggesting glandular receptor saturation at this dose. Despite suppression of tear production, no corneal pathologic factors were observed. Further studies are needed to refine this animal model with the ultimate goal of determining optimum delivery route and concentration to reduction in tear production while minimizing side effects in patients.

Isolated unilateral congenital lacrimal gland agenesis presenting as filamentary keratopathy in a child.

Congenital lacrimal gland agenesis is extremely rare, and there are only a few cases reported in the literature. These cases involve bilateral lacrimal gland agenesis associated, in some instances, with salivary gland agenesis and abnormalities of the lacrimal puncta and canaliculi. This report, to our knowledge, presents the first documented case of unilateral lacrimal gland agenesis, resulting in unilateral filamentary keratopathy.