Incorporation and differentiation of hippocampus-derived neural stem cells transplanted in injured adult rat retina.
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PURPOSE: In a previous study it has been shown that adult rat hippocampus-derived neural stem cells can be successfully transplanted into neonatal retinas, where they differentiate into neurons and glia, but they cannot be transplanted into adult retinas. In the current study, the effect of mechanical injury to the adult retina on the survival and differentiation of the grafted hippocampal stem cells was determined. METHODS: Mechanical injury was induced in the adult rat retina by a hooked needle. A cell suspension (containing 90,000 neural stem cells) was slowly injected into the vitreous space. The specimens were processed for immunohistochemical studies at 1, 2, and 4 weeks after the transplantation. RESULTS: In the best case, incorporation of grafted stem cells was seen in 50% of the injured retinas. Most of these cells located from the ganglion cell layer through the inner nuclear layer close to the injury site. Immunohistochemically, at 1 week, more than half of the grafted cells expressed nestin. At 4 weeks, some grafted cells showed immunoreactivity for microtubule-associated protein (MAP) 2ab, MAP5, and glial fibrillary acidic protein (GFAP), suggesting progress in differentiation into cells of neuronal and astroglial lineages. However, they showed no immunoreactivity for HPC-1, calbindin, and rhodopsin, which suggests that they did not differentiate into mature retinal neurons. Immunoelectron microscopy revealed the formation of synapse-like structures between graft and host cells. CONCLUSIONS: By the manipulation of mechanical injury, the incorporation and subsequent differentiation of the grafted stem cells into neuronal and glial lineage, including the formation of synapse-like structures, can be achieved, even in the adult rat retina. (+info)
Retinal damage by air infusion during vitrectomy in rabbit eyes.
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PURPOSE: Visual field defects after vitrectomy can be seen after any surgery involving fluid-air exchange. To elucidate the effect during surgery of the infused air on the retina, the present study investigated the changes in the morphology of the rabbit retina induced by air infusion and the changes resulting from varying amounts of infused air pressure. METHODS: Eighteen eyes of 18 rabbits were used. A standard three-port vitrectomy with artificial posterior vitreous detachment followed by fluid-air exchange was performed in 12 eyes. During the fluid-air exchange, humidified air was infused with an air pressure of 25 or 40 mm Hg for 30 seconds. As a control, vitrectomy without fluid-air exchange was performed in six eyes. The eyes were enucleated and fixed immediately. Specimens were processed and examined by light and scanning electron microscopy (SEM). RESULTS: With SEM, sharply demarcated retinal lesions were observed at the opposite side from the infusion cannula in all eyes in which a fluid-air exchange was performed. At the lesion, the internal limiting membrane was often detached, and the underlying nerve fiber layer was exposed. Light microscopy revealed that the inner retina was most affected, with concomitant swelling of the inner plexiform layer and the inner granular layer. In addition, the retina was often focally detached with adhesion of some retinal pigment epithelial cells to the photoreceptor cells. Increased infused air pressure was accompanied by a significant increase in the area of retinal damage. In contrast, no morphologic change was observed in the control eyes. CONCLUSIONS: Air infusion during vitrectomy can cause mechanical retinal damage in the rabbit retina. The mechanical damage may result in a visual field defect after vitrectomy. (+info)
Ocular sports injuries: the current picture.
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OBJECTIVES: To determine the recent incidence of eye injury due to sport in Scotland, identify any trend, and establish which sports are responsible for most injury? The type of injury and final visual outcome is also evaluated. METHODS: A prospective observational study of ocular injuries sustained during sport was performed over a one year period. Only patients requiring hospital admission were included. Data were collected on a standardised proforma and entered into a central database. Patients were followed up for at least three months. RESULTS: Of 416 patients admitted because of ocular injury, 52 (12.5%) resulted from playing a sport. Although all racquet sports together accounted for 47.5% of these injuries, football was the single most common sport associated with ocular trauma, being responsible for 32.5% of cases. The most common clinical finding was macroscopic hyphaema occurring in 87.5% of patients. Overall the final visual acuity was 6/6 in 92.5% of patients. CONCLUSIONS: The incidence of eye injury due to sport at 12.5% is lower than previously reported, suggesting a change in the pattern of ocular trauma. Football is the single most common cause of ocular injury from sport in Scotland, but the wearing of protective headgear would be difficult to instigate. The incidence of hyphaema in sport related ocular trauma (87.5%) is almost double that of all ocular injury (47.8%), so the potential for serious visual loss as the result of a sports injury should not be underrated. Ophthalmologists have a role in protecting this young population at risk by actively encouraging the design and use of protective eyewear. (+info)
Trabeculectomy with mitomycin C in the treatment of post-traumatic angle recession glaucoma.
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AIM: The presence of traumatic angle recession is a risk factor for failure of glaucoma filtration surgery and a previous study has suggested that antimetabolite treatment should be used in these patients. This study was undertaken to determine for the first time the mid term results of trabeculectomy with intraoperative application of mitomycin C in patients with post-traumatic angle recession glaucoma. METHODS: A retrospective analysis was made of 43 consecutive trabeculectomy procedures in 41 young black/mixed race patients followed for a mean period of 25 months (range 2-66 months). Mitomycin C 0.02% was applied between the sclera and conjunctiva for 1-5 minutes at the time of surgery. The intraocular pressure and visual acuity were measured postoperatively. The success of this technique was analysed by using a Kaplan-Meier cumulative survival curve. RESULTS: The intraocular pressure was successfully controlled at last follow up without topical treatment in 77% (33/43 eyes) and the visual acuity was the same or better in 81% (35/43 eyes). Cumulative probability of success was 85% at 1 year follow up, 81% at 2 years, and 66% at 3 years and thereafter. Hypotonous maculopathy occurred in one patient and no cases of late bleb infection were found. CONCLUSIONS: In medically uncontrolled post-traumatic angle recession glaucoma trabeculectomy with mitomycin C is an effective surgical procedure with an acceptable complication rate. Good intraocular pressure control and preservation of vision can be expected in most patients. (+info)
Pathways for the response of the eye to injury.
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The role of a neural pathway in the disruption of the blood-aqueous barrier of the rabbit after two irritating stimuli, topical nitrogen mustard, and paracentesis, was studied. Retrobulbar anesthesia or section of the ophthalmic division of the trigeminal nerve decreased the breakdown of the blood-aqueous barrier, as measured by protein in the aqueous humor, after topical nitrogen mustard. Sensory denervation, accomplished with retrobulbar alcohol, virtually prevented the protein rise in the aqueous humor. Disruption of the blood-aqueous barrier after paracentesis, however, was not affected by retrobulbar anesthesia or alcohol denervation. Therefore, the increased protein in the aqueous humor after an irritative stimulus appears to be mediated by at least two pathways. The response to a stimulus such as nitrogen mustard depends on sensory innervation and is not mediated by prostaglandins to any important degree. The response to paracentesis does not require sensory innervation and appears to be mediated, at least in part, by prostaglandins. (+info)
Unusual presentations of accommodative esotropia.
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PURPOSE: Most patients with accommodative esotropia are first examined between the ages of 6 months and 2 years. This paper discusses unusual presentations of accommodative esotropia that occur outside of this age-group and/or have a precipitating event that triggered the esotropia. In a series of patients who were from 5 to 11 years of age, trauma was the precipitating event. In some of the patients under 6 months of age, high myopia, as well as a moderate to large amount of hyperopia, was the cause. In 1 teenager, diabetic ketoacidosis precipitated accommodative esotropia. METHODS: We reviewed all of our records for the past 25 years involving patients with a diagnosis of esotropia, and we found 17 patients who had unusual presentations of accommodative esotropia. Of 8 who were under the age of 6 months, 2 had high myopia and 6 had moderate to large amounts of hyperopia. Nine patients were older than age 5. Eight of the 9 had suffered trauma associated with the presentation of accommodative esotropia, and 1 patient's accommodative esotropia was associated with diabetes. The patients with myopia received their full myopic correction. The children under 6 months of age with hyperopia received their full cycloplegic refraction, and the children over age 5 received the most plus that they were able to accept in a noncycloplegic state consistent with good visual acuity (at least 20/30 in each eye). RESULTS: In 17 patients, accommodative esotropia was initially controlled with glasses. In a few of the trauma cases, bifocals were required for control of near deviation. Only 2 of the patients, in whom onset was under 6 months of age, came to surgery. One had hyperopia controlled for 2 years with glasses, and the other had myopia controlled for 3 years with glasses. CONCLUSIONS: Accommodative esotropia can occur prior to 6 months of age. It can also occur in older children (5 to 14 years of age) and can be precipitated by trauma or diabetic ketoacidosis. (+info)
Combined pars plana lensectomy-vitrectomy with open-loop flexible anterior chamber intraocular lens (AC IOL) implantation for subluxated lenses.
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OBJECTIVES: To review our experience with combined pars plana lensectomy-vitrectomy and open-loop flexible anterior chamber intraocular lens (AC IOL) implantation for managing subluxated crystalline lenses. METHODS: Retrospective review of 36 consecutive eyes (28 patients), all of which had subluxated crystalline lenses, managed by pars plana lensectomy-vitrectomy with insertion of an open-loop flexible AC IOL. The study was performed at the Medical College of Wisconsin, Milwaukee, over an 8-year period. RESULTS: An average preoperative visual acuity of 20/163 (range, 20/25 to hand motions) improved to 20/36 (range, 20/20 to 4/200) with surgery after a mean follow-up of 14 months (range, 1 to 59 months) (P < .001, Student's paired t test). Final visual acuity of 20/40 or better was achieved in 75% of eyes (27/36). Complications included cystoid macular edema (8% [3/36]), pupillary block (6% [2/36]), retinal detachment (3% [1/36]), hyphema (3% [1/36]), wound leak (3% [1/36]), and transient vitreous hemorrhage (3% [1/36]). No persistent ocular hypertension was seen, nor did angle abnormalities or corneal decompensation develop. CONCLUSIONS: Pars plana lensectomy-vitrectomy with AC IOL implantation appears to be an excellent technique for managing subluxated crystalline lenses. It is associated with a significant improvement in visual acuity (P < .001) and avoids many of the complications seen with extraction of a subluxated lens through a limbal wound. Additionally, use of an AC IOL offers a simplified alternative to placement of a ciliary sulcus sutured posterior chamber intraocular lens (PC IOL). (+info)
The effect of scleral search coil lens wear on the eye.
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BACKGROUND/AIM: Scleral search coils are used to measure eye movements. A recent abstract suggests that the coil can affect the eye by decreasing visual acuity, increasing intraocular pressure, and damaging the corneal and conjunctival surface. Such findings, if repeated in all subjects, would cast doubt on the credibility of the search coil as a reliable investigative technique. The aim of this study was to reassess the effect of the scleral search coil on visual function. METHODS: Six volunteer subjects were selected to undergo coil wear and baseline measurements were taken of logMAR visual acuity, non-contact tonometry, keratometry, and slit lamp examination. Four drops of 0.4% benoxinate hydrochloride were instilled before insertion of the lens by an experienced clinician. The lens then remained on the eye for 30 minutes. Measurements of the four ocular health parameters were repeated after 15 and 30 minutes of lens wear. The lens was then removed and the health of the eye reassessed. RESULTS: No obvious pattern of change was found in logMAR visual acuity, keratometry, or intraocular pressure. The lens did produce changes to the conjunctival and corneal surfaces, but this was not considered clinically significant. CONCLUSION: Search coils do not appear to cause any significant effects on visual function. However, thorough prescreening of subjects and post-wear checks should be carried out on all coil wearers to ensure no adverse effects have been caused. (+info)