Surgical management of retinal traction caused by toxocariasis

We reviewed the results of vitreous surgery in 12 eyes of 12 patients with tractional macular detachment from Toxocara canis. We performed a vitrectomy and membrane peeling in all eyes, with additional scleral buckling in four eyes. After a minimum of six months' follow-up, ten of the 12 eyes (83%) had complete retinal reattachment. Visual acuity improved in seven eyes, two had no change, and three eyes had decreased visual acuity. Good postoperative vision correlated best with good preoperative vision. Preoperative traction retinal folds through the macula were associated with a poor visual outcome.     

A simplified approach to the treatment of Duane's syndrome

INTRODUCTION: To report the results of a large series of patients undergoing treatment for Duane's syndrome. METHODS: Patients with Duane's syndrome undergoing strabismus surgery of a horizontal muscle recession procedure, medial rectus recession for an esodeviation or lateral rectus recession for an exodeviation, in order to correct an abnormal head position (AHP) and a significant tropia in primary position were identified. Amount of recession varied with the angle of deviation in forced primary position, versions and ductions, and intraoperative forced ductions. Elimination of AHP was used as a criterion for success. RESULTS: Fifty nine patients were treated with either unilateral or bilateral medial or lateral rectus recession. Mean follow up was 3.1 years. Ninety three percent achieved a postoperative alignment of < or =15 degrees AHP, 66% achieved < or =5 degrees AHP. Only three patients, two from the unilateral Type II group and one from the bilateral combined Types I and II group, went on to have a second procedure for a noticeable residual AHP. CONCLUSIONS: Success (good to excellent results) of horizontal muscle recession was achieved in 93% of patients. Unilateral or bilateral horizontal rectus muscle recession offers a simple and effective surgical option for eliminating AHP and is our treatment of choice in patients with Duane's syndrome.     

A new approach to the problem of retinal neovascularization

Tumor cells introduced into the rabbit vitreous produced a form of retinal neovascularization, but only when the tumor cells were in direct contact with the vascularized retina. This contrasted with the production of neovascularization at a distance of several millimeters in other angiogenesis models. An extract of adult rabbit vitreous was found to inhibit the growth of limbal neovascularization induced by tumors implanted in the rabbit corneal stroma. The experimental model of retrolental fibroplasia provides a bioassay to investigate further the apparent inhibitory substances in the vitreous.     

A clinical approach to the diagnosis of retinal vasculitis

Retinal vasculitis is a sight-threatening inflammatory eye condition that involves the retinal vessels. Detection of retinal vasculitis is made clinically, and is confirmed with the help of fundus fluorescein angiography. Active vascular disease is characterized by exudates around retinal vessels resulting in white sheathing or cuffing of the affected vessels. In this review, a practical approach to the diagnosis of retinal vasculitis is discussed based on ophthalmoscopic and fundus fluorescein angiographic findings.     

Experimental traction retinal detachment in the cat

We developed a reproducible model of traction retinal detachment (TRD) in the cat eye by creating a serous retinal detachment and then injecting 2.5 × 10⁵ kitten dermal fibroblasts into the vitreous cavity at the site of a retinal wound. Serous detachments were produced by exposing an area of retina to focused light after intravenous injection of rose bengal (a photosensitizing dye). TRD developed rapidly within the first 2 weeks after fibroblast injection, accompanied by the formation of vitreoretinal strands and, to a lesser degree, epiretinal and/or subretinal proliferation. Histopathology demonstrated fibroblasts within the vitreous or along the posterior hyaloid face. Focal deposits of fibroblasts were occasionally found on the inner surface of the retina and/or in the subretinal space. Fibroblast proliferation was confirmed by uptake of radiolabeled thymidine. Deposition of collagen was noted at as early as 3 days after fibroblast injection. Neovascularization was not observed. Control eyes that did not receive fibroblasts showed resolution of serous detachment without retinal traction. In all eyes, retinal degeneration and thinning were seen in the area of previous photodynamic treatment. In this model of TRD, anteroposterior traction (due to vitreous strands) predominates, as is observed in experimental posterior penetrating ocular injury induced by intravitreal blood injection, which also results in vitreous strand formation. Our model, however, enables clinical assessment of TRD in the cat without the media opacification produced by vitreous blood. Offprint requests to: D.L. HatchellSupported by VA medical research funds, NIH research grant EY02903, core grant EY05722, the Helena Rubinstein Foundation, New York, and Research to Prevent Blindness, Inc., New York. Dr. D.L. Hatchell is a Research to Prevent Blindness, Inc., Senior Scientific Investigator. The authors have no commercial or proprietary interest in the chemicals, drugs, or devices used in this study     

Bevacizumab prior to vitrectomy for diabetic traction retinal detachment

Purpose

To assess the efficacy and safety of preoperative intravitreal bevacizumab (IVB) before vitrectomy for diabetic tractional retinal detachment (TRD).

Methods

Using ICD-9 codes, we located all patients with diabetic TRD who underwent 3-port 20-gauge vitrectomy primarily performed by one surgeon between January 2004 and January 2009. Eyes receiving IVB were compared with those not. The following outcomes were compared: visual acuity (VA), duration of surgery, and complication rates.

Results

A total of 99 eyes of 90 patients were included in the analysis. In all, 34 patients received IVB on an average of 11.5 (range, 3–30) days previtrectomy. Age was 46.5 and 51.6 in the IVB and non-IVB groups, respectively. VA was improved significantly in both groups: from 20/617 to 20/62 in the IVB group, and from 20/443 to 20/86 in the non-IVB group (P=0.11 between groups). Operating time and postoperative complications (glaucoma, RD, and revitrectomy rate) were similar in both groups. On comparing IVB and non-IVB eyes in younger patients (≤40), operating time was shorter (P=0.02) and a trend to better VA in the IVB group was seen.

Conclusions

Preoperative IVB may be a useful adjunct to vitrectomy for severe PDR complicated by TRD, particularly in younger diabetics.     

Blood coagulation factor XIII contributes to the development of traction retinal detachment

The blood coagulation factor XIII catalyzes the crosslinking of fibrin monomers at the end of the coagulation cascade. Additional functions are the enzymatic coupling of fibrinectin to itself, fibrin, and collagen. We located the two subunits of factor XIII in 20 surgically obtained periretinal membranes, using double label immunofluorescence microscopy. Both subunits of factor XIII could be detected in all specimens. The positive staining in all specimens examined prompted us to determine the source of factor XIII. The abundant fibroblastic cells did not contain factor XIII. Macrophages, half of which stained for the alpha-subunit of factor XIII could not account for the presence of factor XIII because these cells were not present in all specimens, and did not stain for the beta-subunit. Factor XIII is probably derived from the exudation of plasma and platelets through disrupted blood-ocular barriers. This is confirmed by the detection of both subunits in vitreous aspirates from patients with proliferative intraocular disorders (n = 15) by Western blotting.     

Proliferative retinal diseases: myofibroblasts cause chronic vitreoretinal traction.

Myofibroblasts are contractile cells having features intermediate between those of the fibroblast and smooth muscle. Myofibroblasts in preretinal membranes may cause retinal traction in proliferative retinal diseases. In this study, we demonstrate the presence of a chronically contractile subpopulation of myofibroblasts in pre-retinal membranes. Apha smooth muscle actin or desmin, both markers of the myogenically differentiated and chronically contractile subpopulation could be detected in a large majority of the examined membranes. Our findings may serve to explain the cellular basis of vitreoretinal traction in proliferative vitreoretinopathy and proliferative diabetic retinopathy.     

Clinical results in vitrectomy for diabetic traction retinal detachment.

A series of 75 eyes underwent pars plana vitrectomy for progressive diabetic traction retinal detachment of the macula. In all cases, the media was sufficiently clear to allow preoperative macular examination. The overall visual improvement was higher in phakic eyes (80%) than aphakic eyes (72%) and the rate of neovascular glaucoma was less in phakic eyes. The difference was not statistically significant, however. The final visual acuity corresponded to the degree of preoperative visual deterioration. Thus, surgery during the rapidly evolving proliferative and retracting process did not adversely affect the visual success rate when compared to previous reports on longstanding vitreous hemorrhage.     

A systematic approach to the management of microspherophakia

Microspherophakia is a rare developmental abnormality of the crystalline lens with a myriad of ocular and systemic associations. Glaucoma is a serious complication associated with this disorder. Early identification of the disease, timely visual rehabilitation, and appropriate management of the lens and glaucoma can help us prevent blindness from this condition. Multidisciplinary care with lifelong follow-up is recommended, as this typically affects the younger population. Current treatment protocols for this condition are mainly based on case reports and retrospective studies with shorter follow-up. Due to the rarity of this disease, designing a large randomized controlled trial to identify the merits and demerits of each management strategy is challenging. With cataract, glaucoma, and vitreoretinal specialists, each having their preferred way of managing microspherophakic lenses, we decided to do a comprehensive review of the existing literature to devise an integrated approach toward effective management of these patients. This review will collate all evidence and provide a very practical decision-making tree for its management.     

The role of tangential dispersion in retinal mosaic formation

Individual types of retinal nerve cell are spaced across the retina in an orderly manner, ensuring a uniform sampling of the visual field. This regularity in cellular spacing has been commonly attributed to fate determination mechanisms operating around the time of cell birth, an hypothesis presuming that the position of a nerve cell is fixed within the plane of the retina from the time of its determination. At odds with this view, recent results from X-inactivation mosaic mice indicate that certain classes of retinal nerve cell, those known to form orderly mosaics in the adult retina, disperse tangentially during development. Furthermore, studies defining the spatial characteristics of developing and mature retinal mosaics suggest that cell-cell interactions around the time of morphological differentiation lead to mutual repulsion. Modelling studies in turn show that nothing more than a simple minimal spacing rule between neighboring cells of the same type is sufficient for the creation of the global patterning observed in biological retinal mosaics. For some cell types, the size of this "exclusion zone" surrounding individual cells is shown to be an intrinsic characteristic of each cell type, invariant across the retina, and accounting for the variation in mosaic regularity across changes in cell density. These results show how short-distance movements driven by intercellular interactions at the local level may mediate the emergence of the global patterning characteristic of retinal mosaics during development.     

A multivariate approach to structural heterogeneity of retinal ganglion cells

Knowing neuronal types is essential for understanding the structural and functional organization of the nervous system. It has long been recognized that neuronal types should be discovered and not defined. This can be done using cluster analysis (CA). Despite there being many studies using CA to classify neurons, only a few of them meet its formal prerequisites. In the present study, we provide an example of using CA in combination with other multivariate techniques for examining neuronal diversity. A special emphasis is put on formal prerequisites to the data and procedure. The data under scrutiny are a sample of ganglion cells projecting to the basal optic nucleus [accessory optic system-projecting ganglion cells (AOS GCs)] in the common frog. There is physiological evidence that these cells comprise at least two functional types but their structural heterogeneity has not been addressed. Cells were labeled with horseradish peroxidase in vivo and examined in whole-mounted retinae using light microscopy. A sample of well-stained cells was obtained and used to estimate 18 structural parameters. A variety of clustering algorithms were used to classify the cells. The joint polar distribution of dendrite mass was monomodal. CA did not reveal a statistically reliable cluster structure in the sample. The clusters were not cohesive and well isolated. ANOVA-on-Ranks revealed no significant between-cluster differences. Our formal conclusion is that functionally distinct frog AOS GCs do not differ in morphology or dendritic arbor orientation. The advantages and limitations of the adopted approach are discussed.