Alexander J. Brucker

Genetic variants near TIMP3 and high-density lipoprotein–associated loci influence susceptibility to age-related macular degeneration

We executed a genome-wide association scan for age-related macular degeneration (AMD) in 2,157 cases and 1,150 controls. Our results validate AMD susceptibility loci near CFH (P < 10−75), ARMS2 (P < 10−59), C2/CFB (P < 10−20), C3 (P < 10−9), and CFI (P < 10−6). We compared our top findings with the Tufts/Massachusetts General Hospital genome-wide association study of advanced AMD (821 cases, 1,709 controls) and genotyped 30 promising markers in additional individuals (up to 7,749 cases and 4,625 controls). With these data, we identified a susceptibility locus near TIMP3 (overall P = 1.1 × 10−11), a metalloproteinase involved in degradation of the extracellular matrix and previously implicated in early-onset maculopathy. In addition, our data revealed strong association signals with alleles at two loci (LIPC, P = 1.3 × 10−7; CETP, P = 7.4 × 10−7) that were previously associated with high-density lipoprotein cholesterol (HDL-c) levels in blood. Consistent with the hypothesis that HDL metabolism is associated with AMD pathogenesis, we also observed association with AMD of HDL-c—associated alleles near LPL (P = 3.0 × 10−3) and ABCA1 (P = 5.6 × 10−4). Multilocus analysis including all susceptibility loci showed that 329 of 331 individuals (99%) with the highest-risk genotypes were cases, and 85% of these had advanced AMD. Our studies extend the catalog of AMD associated loci, help identify individuals at high risk of disease, and provide clues about underlying cellular pathways that should eventually lead to new therapies.

Evolving guidelines for intravitreous injections.

Intravitreous (IVT) injection is increasingly being incorporated into the management of ocular diseases. While only fomivirsen sodium (Vitravene™) is currently approved by the Food and Drug Administration as an IVT injection, the number of approved IVT injections indications is anticipated to grow on the basis of promising results from ongoing clinical studies. Despite the potential benefits that may be derived from intraocular injections of different agents, no guidelines have been published previously for IVT injection. The purpose of this document is to identify specific strategies for the delivery of IVT injection that may reduce risks and improve outcomes. Consensus was sought among a panel of investigators, surgeons experienced with this technique, and industry representatives. Objective evidence was sought for all guidelines, but consensus was accepted where evidence remains incomplete. In the absence of either evidence or consensus, the current manuscript identifies outstanding issues in need of further investigation. It is anticipated that more complete guidelines will evolve over time, potentially altering some of the guidelines included here, based on new applications of IVT injection, additional clinical experience, and results of clinical trials.

Pathology of human cystoid macular edema

The light and electron microscopic findings are reviewed in two patients who had eyes enucleated for peripheral choroidal malignant melanomas. Preoperatively, cystoid macular edema was documented by fluorescein angiography in the melanoma-containing eye in both patients. Intracytoplasmic swelling (edema) of the Müller (glial) cells is the anatomical basis for the macular edema. Intercellular (extracellular) collections of fluid probably are late, endstage results of the process that result form prolonged, excessive, intracellular edema, cell death and disruption. The process probably rests on an ischemic basis, as evidenced by severe changes in the microvasculature. In the one patient in whom the optic nerve was available for study, marked intracellular swelling (edema) of glial cells in the lamina choroidalis of the optic nerve head was present, associated with compression of the adjacent axons. The nearby temporal, parapapillary retina also showed edema of Müller cells, and compression of the nerve fibers (ganglion cell axons), suggesting a more widespread process than was clinically evident. Again, severe changes were present in the microvasculature, both in the optic nerve and parapapillary retina. The underlying cause of the microvasculature changes that lead to ischemia, perhaps an intrinsic pharmacologic agent, is yet to be found.

Macular Edema and Cystoid Macular Edema

We examined the foveomacular regions from three eyes in which fluorescein angiography had demonstrated the characteristic appearance of cystoid macular edema by light and electron microscopy. Cystoid macular edema was present in two eyes (one of which was from a 63-year-old diabetic man) that contained peripheral choroidal melanomas, and in a third eye from a patient with diabetes only. By light microscopy, cystoid macular degeneration was obvious only in the third eye. The electron microscopic findings common to all three eyes were widespread swelling and necrosis of Müller cell cytoplasm. There was no enlargement of intercellular spaces. There was secondary neuronal degeneration. Retinal vascular changes, consisting mainly of endothelial cell abnormalities, were found in all cases but were far more common in the two eyes from diabetic patients. The retinal vascular changes were probably the cause of the cystoid macular edema.

Intravitreal injection of vascular endothelial growth factor small interfering RNA inhibits growth and leakage in a nonhuman primate, laser-induced model of choroidal neovascularization.

Purpose To determine the safety and efficacy of small interfering RNA (siRNA) directed against vascular endothelial growth factor (VEGF) in a nonhuman primate model of laser-induced choroidal neovascularization (CNV). Methods Each animal received laser rupture of Bruch’s membrane to induce CNV in both eyes. Each animal was then randomized to receive 0.05 mL of either vehicle alone or VEGF siRNA at 70 &mgr;g, 150 &mgr;g, or 350 &mgr;g in both eyes by intravitreal injection. Eyes were monitored weekly by ophthalmic examination, color photography, and fluorescein angiography for 36 days after laser injury. Electroretinograms were measured at baseline and at 5 weeks after laser. CNV on fluorescein angiograms were measured for area and graded for clinically significant leakage in a standardized, randomized, and double-masked fashion on days 15, 22, 29, and 36 after laser. Results VEGF siRNA did not cause any change in electroretinographic, hemorrhage, inflammation, or clinical signs of toxicity. A single administration of VEGF siRNA significantly inhibited growth of CNV and attenuated angiographic leakage in a dose-dependent manner. Conclusion Intravitreal injection of VEGF siRNA is capable of inhibiting the growth and vascular permeability of laser-induced CNV in a nonhuman primate in a dose-dependent manner. This study demonstrates preclinical proof of a principle that supports proceeding to clinical studies of VEGF siRNA in patients with exudative age-related macular degeneration.

Altered Retinal Vascular Response to 100% Oxygen Breathing in Diabetes Mellitus

The effect of 100% oxygen breathing on retinal blood flow was investigated using laser Doppler velocimetry in 19 normal eyes, and in 41 eyes of insulin treated diabetic patients. Of the diabetic eyes studied, nine had no retinopathy, 18 had background diabetic retinopathy, seven had proliferative diabetic retinopathy, and seven had proliferative diabetic retinopathy that had been previously treated by argon panretinal photocoagulation. Five minutes of 100% oxygen breathing produced an average decrease in blood flow of 61% (SD = 8) in normal eyes, 53% (SD = 10) in NR eyes, 38% (SD = 13) in background diabetic retinopathy eyes, 24% (SD = 18) in proliferative diabetic retinopathy eyes and 54% (SD = 8) in panretinal photocoagulation eyes. In six eyes with proliferative retinopathy measured before and after panretinal photocoagulation, a significant increase in vascular response to O2 was observed following photocoagulation (Wilcoxon signed rank test, P less than 0.05).

The posterior uveal bleeding syndrome.

Eight patients were observed who suffered varying degrees of visual loss secondary to multiple recurrent hemorrhages or serous fluid beneath the retinal pigment epithelium and neurosensory retina in the posterior fundus. Vitreous hemorrhage occurred in two patients. In all patients, hemorrhages or exudates were associated with orange subretinal lesions of which the clinical and fluorescein angiographic appearances were not previously familiar to the authors. Six of the eight patients were female, and all but one was black. Ages ranged from 40 to 79 years (median, 57 years). Final visual acuities ranged from 20/40 to hand motions. The term “posterior uveal bleeding syndrome” is proposed to describe these findings.

Vision-threatening Complications of Surgery for Full-thickness Macular Holes

OBJECTIVE To study complications of vitrectomy surgery for full-thickness macular holes. DESIGN A multicentered, randomized, controlled clinical trial. PARTICIPANTS Community and university-based ophthalmology clinics. INTERVENTION Standardized macular hole surgery versus observation. MAIN OUTCOME MEASURES Assessment of anatomic and visual outcomes and determination of postoperative complications at 12 months after randomization. RESULTS Posterior segment complications were noted in 39 eyes (41%). The incidence of retinal pigment epithelium (RPE) alteration and retinal detachment (RD) were 33% and 11%, respectively. One RD due to a giant retinal tear resulted in a visual acuity of light perception. Other complications included a reopening of the macular hole in 2 eyes (2%), cystoid macular edema in 1 eye (1%), a choroidal neovascular membrane in 1 eye (1%) and endophthalmitis in 1 eye (1%). Eyes with complications had significantly worse visual acuity outcomes as determined by the Early Treatment Diabetic Retinopathy Study, Word Reading, and Potential Acuity Meter charts (P < 0.01 for all comparisons). Eyes with macular holes greater than 475 microns were more than twice as likely to have complications than eyes with holes less than 475 microns (odds ratio [OR] = 2.2, P = 0.07). Before surgery, the stage of the hole was related to postoperative RPE changes (P < 0.0001) and the occurrence of postoperative RD (P = 0.0002). Intraoperative trauma was related to the occurrence of these complications (P < 0.0001 for RPE changes, P = 0.02 for RDs). Epiretinal membrane removal was related to RPE changes (P = 0.02) but not RDs. CONCLUSIONS The RPE alterations and RDs are common after macular hole surgery and result in significantly reduced postoperative visual acuity. The RPE changes may be related to surgical trauma or light toxicity. Further efforts to reduce complications associated with macular hole surgery are indicated.

Combined Hamartomas of the Retina and Retinal Pigment Epithelium

Combined hamartomas of the retina and retinal pigment epithelium are rare fundus lesions. By combining cases seen by members of The Macula Society, clinical data was collected on 60 patients with combined hamartomas. We reviewed the clinical presentations, ophthalmoscopic, and fluorescein angiographic features and differential diagnosis of this tumor. Of 41 patients with adequate follow-up information, 10 (24%) lost at least two lines of visual acuity, usually due to tractional distortion of the fovea, and four (10%) had improved visual acuity following either amblyopia therapy or vitreous surgery for macular traction.

Risk of Endophthalmitis After Intravitreal Drug Injection When Topical Antibiotics Are Not Required: The Diabetic Retinopathy Clinical Research Network Laser-Ranibizumab-Triamcinolone Clinical Trials

OBJECTIVE To report the incidence of endophthalmitis after intravitreal drug injection by means of a standardized procedure that does not require topical antibiotics, sterile gloves, or a sterile drape. METHODS Intravitreal injections of preservative-free triamcinolone acetonide or ranibizumab were administered in 2 prospective randomized clinical trials performed by the Diabetic Retinopathy Clinical Research Network. The standardized procedure for these trials requires the use of a topical combination product of povidone-iodine, a sterile lid speculum, and topical anesthetic, but does not require the use of topical antibiotics before, on the day of, or after injection. RESULTS As of February 23, 2009, a total of 3226 intravitreal injections of ranibizumab and 612 injections of preservative-free triamcinolone had been administered. Topical antibiotics were given on the day of injection in 361 (9.4%) of the 3838 cases, for several days after injection in 813 cases (21.2%), on the day of injection and after injection in 1388 cases (36.2%), and neither on the day of injection nor after injection in 1276 cases (33.3%). Three cases of culture-positive endophthalmitis occurred after ranibizumab injections (0.09%), and no cases occurred after triamcinolone injections. In all 3 cases of endophthalmitis, topical antibiotics were given for several days after the injection but not before injection. CONCLUSIONS The results suggest that a low rate of endophthalmitis can be achieved by means of a protocol that includes use of topical povidone-iodine, a sterile lid speculum, and topical anesthetic, but does not require topical antibiotics, sterile gloves, or a sterile drape. Trial Registration clinicaltrials.gov Identifiers: NCT00444600 and NCT00445003.