Volume 5, Number 3
Monday, January 24, 2005



In this issue: (click heading to view article)
Visual, Topographic and Endothelial Cell Counts One to Two Years After DLEK
Inhibition of Corneal Angiogenesis by Local Application of Vasostatin
Association Between Visual Attention and Mobility in Older Adults
Stage 0 Macular Holes: Observations by OCT
Recovery of Contour Integration and logMAR Visual Acuity in Children With Amblyopia
Briefly











Visual, Topographic and Endothelial Cell Counts One to Two Years After DLEK

The Lions Vision Research Laboratory, Portland, OR, evaluated whether the visual, topographic and endothelial cell count results observed one year after deep lamellar endothelial keratoplasty (DLEK) surgery remain stable up to two years after surgery.

In a prospective, noncomparative, interventional case series, 20 eyes of 20 patients with corneal edema from Fuchs" endothelial dystrophy underwent DLEK replacement surgery, with a 9.0-mm or 9.5-mm scleral access incision and a specialized intrastromal trephine. Snellen visual acuities, corneal topography and endothelial cell counts were prospectively measured preoperatively and one and two years after DLEK.

At one year postoperatively, best spectacle-corrected visual acuity (BSCVA) averaged 20/50 (range, 20/25 to 20/200), spherical equivalents (SE) averaged -0.194 +/- 1.521D, manifest refraction (MR) astigmatism averaged 2.04 +/- 1.05 D (range, 0.0 to 4.0D), topographic astigmatism averaged 2.3 +/- 1.1D, mean corneal curvature was 43.2 +/- 1.8D, surface regularity index (SRI) averaged 1.16 +/- 0.41 and surface asymmetry index (SAI) averaged 1.05 +/- 1.09. At two years postoperatively, BSCVA averaged 20/48 (range, 20/25 to 20/200), SE averaged -0.369 +/- 1.267D, MR astigmatism averaged 1.76 +/- 0.66D (range, 0.75 to 3.0D), topographic astigmatism averaged 2.4 +/- 1.1D, mean corneal curvature was 43.6 +/- 1.8D, SRI averaged 1.13 +/- 0.44 and SAI averaged 0.76 +/- 0.59. No significant change occurred in visual or topographic parameters between one year and two years postoperatively. Endothelial cell counts averaged 2335 +/- 468 cells/mm2 at one year and 2151 +/- 457 cells/mm2 at two years postoperatively. Investigators concluded that DLEK provides stable refractions, corneal topography, and endothelial cell densities as long as two years after surgery. The absence of corneal sutures in this technique seems to prevent the sutures in/sutures out changes in SE refractions and corneal topography sometimes seen after penetrating keratoplasty (PK), and thus, DLEK appears to be an excellent alternative to PK for patients with endothelial dystrophies.

SOURCE: Ousley PJ, Terry MA. Stability of vision, topography, and endothelial cell density from one year to two years after deep lamellar endothelial keratoplasty surgery. Ophthalmol 2005;112(1):50-7. 		Table of Contents











Inhibition of Corneal Angiogenesis by Local Application of Vasostatin

Local application of the endogenous angiogenesis inhibitor vasostatin (VS) is potentially feasible for treatment of corneal angiogenesis in humans, according to an animal study by Taiwanese researchers.

Investigators expressed and purified recombinant VS and studied its effects on the proliferation of endothelial cells using the methyl thiazolyl tetrazolium (MTT) assay in the absence or presence of angiogenic factors such as basic fibroblast growth factor (bFGF) or vascular endothelial growth factor (VEGF). They induced corneal neovascularization by implanting hydron pellets containing bFGF in rat corneal micropockets. The potency of VS to inhibit corneal angiogenesis was investigated by incorporation of VS with bFGF in hydron pellets or topical application of VS containing eyedrops to rat eyes implanted with bFGF pellets. They then evaluated the extent of corneal neovascularization by microscopic and histological analyses.

VS potently inhibited the growth of endothelial cells in the absence or presence of angiogenic factors such as bFGF or VEGF. In the rat corneal micropocket assay, concurrent incorporation of VS abolished the bFGF induced neovascularization. When formulated in a methylcellulose eye drop, VS remained intact and functional in a 4° C solution for more than seven days. Topical application of VS eye drops potently inhibited bFGF induced neovascularization in rat corneas.

SOURCE: Wu P-C, Yang LC, Kuo H-K, et al. Inhibition of corneal angiogenesis by local application of vasostatin. Mol Vision 2005;11:28-35.		 Table of Contents






Association Between Visual Attention and Mobility in Older Adults

Visual attention impairment and slowed visual processing speed in older adults may be independently associated with mobility problems, according to a cross-sectional study by the University of Birmingham (AL) Department of Ophthalmology.

The study included 342 adults aged 55 to 85 living independently in the community and recruited from primary eyecare practices. In addition to demographic, health and functional information, investigators collected the following variables at the second annual visit of a prospective study on mobility: a test of visual attention/processing speed; a performance mobility assessment; and self-reported measures of falls, falls efficacy, mobility/balance and physical activity.

Lower scores on visual attention/processing speed were significantly related to poorer scores on the performance mobility assessment, even after adjustment for age, sex, race, education, number of chronic medical conditions, cognitive status, depressive symptoms, visual acuity and contrast sensitivity. Scores on the visual attention/processing speed test were unrelated to the self-reported measures of mobility. The authors suggest that interventions to reverse or minimize the progression of mobility dysfunction in older adults should take this common aging-related deficit in visual processing into account.

SOURCE: Owsley C, McGwin G Jr. Association between visual attention and mobility in older adults. J Am Geriatr Soc 2004;52(11):1901-6. 		Table of Contents






Stage 0 Macular Holes: Observations by OCT

Investigators at Tufts University School of Medicine conducted a retrospective, observational case series aimed at introducing the concept of a Stage 0 macular hole based on optical coherence tomography (OCT) observations of the vitreoretinal interface in fellow eyes of patients with unilateral idiopathic macular holes. They also aimed to evaluate the subsequent risk of progression to a full-thickness macular hole.

Medical records of 94 patients with a unilateral Stage 2, 3 or 4 full-thickness macular hole, diagnosed between 1994 and 2000 at the New England Eye Center, were included in the study. Main outcome measure was the development of a full-thickness macular hole in the fellow eye on biomicroscopic fundoscopy or OCT. In 27 (28.7 percent) of 94 clinically normal fellow eyes, OCT detected an abnormality of the vitreoretinal interface but normal foveal anatomy. The vitreoretinal abnormalities were further subclassified into severe (four eyes), moderate (eight eyes), and mild (15 eyes) based on the intensity and morphology of the OCT signal. One of the four severe cases (25 percent) progressed to a full-thickness macular hole, four of the eight moderate cases (50 percent) became full-thickness macular holes, and no mild cases progressed to a full-thickness macular hole. Severe and moderate eyes seemed to share characteristic features on OCT that increased their risk of macular hole development (Stage 0 macular hole). The macular hole-free survival at 48 months was 94 percent for Stage 0-negative patients versus 54 percent for Stage 0-positive patients. Univariate analysis revealed that the presence of a Stage 0 macular hole was significantly associated with an almost six-fold increase in the risk of macular hole formation (relative risk: 5.8, 95 percent confidence interval 1.16 to 28.61).

Investigators describe the presence of a Stage 0 macular hole as having salient features on OCT consisting of normal foveal and normal retinal thickness and including the presence of a preretinal, minimally reflective thin band inserting obliquely on at least one side of the fovea. They believe their research proves that the presence of a Stage 0 macular hole in the fellow eye is a significant risk factor for the development of a second macular hole.

SOURCE: Chan A, Duker JS, Schuman JS, Fujimoto JG. Stage 0 macular holes: Observations by optical coherence tomography. Ophthalmol 2004;111(11):2027-32. 		Table of Contents






Recovery of Contour Integration and logMAR Visual Acuity in Children With Amblyopia

In several studies, researchers have found that integration of orientation information along contours defined by Gabor patches is abnormal in patients with strabismus and in untreated patients with anisometropic amblyopia. In this British study, investigators compared the rate and degree of recovery of contour-integration deficits with the recovery of logMAR visual acuity deficits in patients newly diagnosed with amblyopia secondary to anisometropia, strabismus or both.

Investigators measured contour-detection thresholds and optotype acuity in 17 newly diagnosed anisometropic amblyopes, six patients with strabismic amblyopia and four patients with combined anisometropic and strabismic amblyopia using a card-based procedure. Treatment comprised full refractive correction and full-time total occlusion therapy when necessary. They measured visual function at monthly visits during the course of treatment, with an average follow-up period of 16 weeks (12 to 24 weeks) for the entire group. They obtained complete data from 23 patients through eight weeks of follow-up.

Results showed significant interocular differences in contour-detection thresholds in 16 of the 27 patients at the first visit after initial refractive correction. Interocular differences in contour-detection thresholds declined to normal levels in most of the patients within eight weeks of the initiation of treatment. Interocular acuity differences remained significant in 19 of 23 patients at eight weeks of follow-up and continued to decline, but did not fully normalize, over the remainder of the follow-up period.

Based on these results, the authors of the study believe that refractive correction alone or in combination with occlusion therapy produces a normalization of contour-integration thresholds in amblyopia that is more rapid and complete than that achieved for visual acuity.

SOURCE: Chandna A, Gonzalez-Martin JA, Norcia AM. Recovery of contour integration in relation to logMAR visual acuity during treatment of amblyopia in children. Invest Ophthalmol Vis Sci 2004;45(11):4016-22. 		Table of Contents





BRIEFLY
  • ALCON, ALBANY MOLECULAR RESEARCH TO COLLABORATE. Alcon Research, Ltd., and Albany Molecular Research, Inc., have entered into a two-year collaboration agreement to discover and develop ophthalmic pharmaceuticals. Under the terms of the agreement, AMRI will screen samples from its natural product collections, which include more than 400,000 purified or partially purified fractions obtained from natural product sources and synthetic small molecules. The goal of the collaboration is to identify and develop lead compounds with desired biological activity against ophthalmic-related biological targets. AMRI will also provide custom chemical synthesis services to Alcon. The contract includes fee-for-service provisions and opportunities for AMRI to receive milestone payments based on the achievement of certain development and regulatory benchmarks. AMRI will receive royalty payments on net sales of commercial products that result from the collaboration. For more information on AMRI, go to www.albmolecular.com.
  • HEALTH CANADA EXPANDS APPROVAL OF INTRALASE FS LASER. Health Canada recently granted a device license amendment to IntraLase Corp. for the company"s IntraLase FS femtosecond laser, which replaces the handheld blade historically used to create the corneal flap in LASIK. IntraLase plans to commercialize the IntraLase FS laser in Canada, thereby expanding its global presence to 18 countries worldwide. More than 250,000 IntraLase-initiated LASIK procedures have been sold worldwide. Clinical studies have shown that the IntraLase laser significantly decreases the occurrence of blade-related complications, including invasive corneal incisions, corneal abrasions, "buttonhole" cuts and improperly formed flaps. It is also dramatically less likely to produce overly thin flaps or extremely thick flaps, which could lead to serious complications.
  • DRUG DELIVERY TECH COMPANY ACQUIRES INNORX. SurModics, Inc., a leading provider of surface modification and drug delivery technologies to the medical device industry, has acquired InnoRx, Inc., a company that develops novel therapies for the ophthalmology market. InnoRx was founded by retinal surgeon and inventor Eugene de Juan, Jr., MD. SurModics had already owned less than 20 percent interest in InnoRx; it paid approximately $4.1 million in cash and about 600,000 shares of stock to acquire the remainder. SurModics" initial focus will be to use InnoRx"s technology platform to treat age-related macular degeneration and diabetic macular edema.
  • NEW TOPICAL OPHTHALMIC PRODUCTS INTRODUCED. Fougera, a division of Altana, Inc., has introduced Gentamicin Sulfate Ophthalmic Ointment USP (Sterile) and Gentamicin Sulfate Ophthalmic Solution USP 0.3% (Sterile) to its line of topical ophthalmic products. The new prescription antibiotics are AT-rated to Garamycin O.O. and Garamycin O.S. by Schering. Gentamicin Sulfate Ointment is available in 1/8-ounce tubes; the solution is available in a 5-mL bottle. For more information on the company’s complete line of topicals or other Fougera products, call 800-645-9833 or go to www.fougera.com.

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