Surgical outcomes in adult patients after repair of anterior segment trauma sustained during childhood.

PURPOSE: To evaluate the outcomes and possible benefit of surgery performed on adults for anterior segment trauma sustained during childhood. SETTING: Private practice. METHODS: A retrospective review of patient records was performed. Adult patients who had anterior segment surgery for injuries that occurred during childhood were identified. The surgical outcomes were evaluated to determine whether intervention was beneficial in this subgroup of patients. RESULTS: Six patients were identified. Preoperative best corrected visual acuity (BCVA) was 20/200 or worse in all patients. After surgery, the BCVA in 3 patients had improved to 20/30 or better and in 1 patient, to 20/60. The other 2 patients had less improvement; however, each noted subjective improvement in vision. No major intraoperative or postoperative complications occurred. CONCLUSION: In the absence of evidence of accompanying posterior segment trauma, surgery in adults to correct anterior segment damage from childhood trauma was safe and often beneficial.

Effect of latanoprost on intraocular pressure in steroid-induced glaucoma.

PURPOSE: To study the effect of monotherapy with latanoprost 0.005% on intraocular pressure (IOP) in a prospective nonrandomized clinical trial of patients newly diagnosed with steroid-induced secondary open-angle glaucoma. PATIENTS AND METHODS: Eight patients (16 eyes) with newly diagnosed steroid-associated secondary open-angle glaucoma were prescribed latanoprost 0.005% once a day in each eye. The initial IOP before treatment served as an internal control for each eye. Intraocular pressure was remeasured after 1 month of monotherapy with latanoprost. Investigators (WJS) were blinded to initial IOP at the time of remeasurement. After discontinuation of steroids, IOP was rechecked. If IOP was stable, latanoprost was discontinued. Intraocular pressure was rechecked 2 to 4 weeks later to confirm an association with steroid use. RESULTS: Intraocular pressure was significantly decreased after treatment with latanoprost (18.3 +/- 2.8 mm Hg) compared with initial IOP (25.3 +/- 9.1 mm Hg). This change represented a 28% decrease in IOP compared with baseline levels. Average IOP after discontinuation of steroids and latanoprost (17.3 +/- 1.4 mm Hg) did not differ from IOP measured during treatment with latanoprost, but it was significantly less than the initial IOP before treatment. No adverse effects were noted. CONCLUSIONS: Monotherapy with latanoprost is safe and effective in patients with steroid-induced glaucoma. Advantages include lack of systemic side effects and convenient once-daily dosing.

Effect of latanoprost on intraocular pressure following cataract extraction.

PURPOSE: To compare the effect of latanoprost 0.005% with that of a placebo (balanced salt solution [BSS]) applied after phacoemulsification on intraocular pressure (IOP). SETTING: Pasco Eye Institute, New Port Richey, Florida, USA. METHODS: A group of patients having cataract extraction by phacoemulsification was randomized following surgery to receive one drop of latanoprost 0.005% (1.5 micrograms) or a placebo (BSS). Exclusion criteria included ocular diagnosis in addition to cataract, previous eye surgery, history of glaucoma, previous use of glaucoma medications, or vitreous loss during surgery. Standard phacoemulsification was performed through a scleral tunnel approach and a one-piece, poly(methyl methacrylate) intraocular lens implanted in the capsular bag. Approximately 24 hours after surgery, IOP was measured with a Goldmann applanation tonometer by the surgeon. The anterior chamber reaction was qualitatively graded from 1+ to 4+. RESULTS: The study included 103 eyes (latanoprost = 53; control = 50). Latanoprost treatment resulted in significantly lower postoperative (IOP) (16.4 mm Hg +/- 3.7 [SD]) than preoperative IOP (17.9 +/- 3.0 mm Hg) (P < .025). There was no decrease in postoperative IOP in the control group (18.2 +/- 3.5 mm Hg) compared with preoperative IOP (18.3 +/- 2.6 mm Hg). When two groups were compared, postoperative IOP after treatment with latanoprost was significantly less than control IOP (P < .01). Preoperative IOP was not significantly different in the placebo and latanoprost groups. Anterior chamber reaction was not increased by latanoprost; it averaged 1+ in both groups. CONCLUSIONS: Latanoprost may pharmacologically enhance uveoscleral outflow immediately after cataract extraction. In this study, latanoprost was a safe, effective method of reducing postoperative IOP.

Implications of early systemic therapy on the incidence of endogenous fungal endophthalmitis.

OBJECTIVE: In the past, evidence of endogenous fungal endophthalmitis has been used as a guide to initiating potentially toxic antifungal therapy in patients with systemic fungal infections. Recently, however, a trend has developed to provide patients with antifungal therapy at the first evidence of fungal infection. The authors' study evaluates the incidence of endogenous fungal endophthalmitis in this setting. DESIGN: The design is a retrospective review of the medical records of patients examined by the inpatient ophthalmology consultation service to rule out endogenous fungal endophthalmitis between January 1994 and April 1996 at the University of Michigan Hospitals, Ann Arbor, Michigan. PARTICIPANTS: Two hundred fourteen eyes of 107 patients with a diagnosis of systemic fungal infection were studied. INTERVENTION: A review of medical records was performed. MAIN OUTCOME MEASURES: The findings of the ocular examination, the presence of risk factors for disseminated fungal infection, the type of antifungal therapy, and the source and identity of the isolated fungus were recorded. RESULTS: The majority of patients examined had either fungal growth from blood cultures or evidence of deep tissue fungal infection. All patients in the study were at risk for fungal disease with each having at least one risk factor for disseminated fungal infection. Of the patients examined, 93.4% already were receiving systemic antifungal therapy at the time of ophthalmologic consultation. Only 3 (2.8%) of the 107 patients examined had chorioretinal findings consistent with early endogenous fungal endophthalmitis. None had intravitreous involvement, and the ocular findings did not change the course of therapy. CONCLUSIONS: Early systemic treatment of deep tissue fungal infection appears to dramatically decrease the incidence of endogenous fungal endophthalmitis.

Differential intertectal delay between Rana pipiens and Xenopus laevis: implications for species-specific visual plasticity.

In the frog Xenopus laevis, the isthmotectal projection, which relays input from the ipsilateral eye, exhibits anatomical reorganization following surgical eye rotation performed during tadpole stages while the isthmotectal projection in the frog Rana pipiens fails to show reorganization. This plasticity has been shown to be dependent upon activation of the N-methyl-D-aspartate (NMDA) receptor located on tectal cell dendrites. The reorganization process in Xenopus is hypothesized to employ a Hebbian mechanism requiring correlated firing of ipsilateral and contralateral inputs to a given tectal cell; when an ipsilateral axon synapses onto a tectal cell that receives input from a contralateral axon with a matching receptive-field location, the correlation in activity triggers stabilization of the ipsilateral synapse. However, in neither Xenopus nor Rana do ipsilateral and contralateral inputs begin to fire simultaneously in response to a given visual stimulus; the ipsilateral input is delayed because it reaches the tectum indirectly, through a polysynaptic relay via the opposite tectum and nucleus isthmi. The objective of this experiment was to test whether there is a significant difference in this intertectal delay between Xenopus laevis and Rana pipiens in order to determine whether intertectal delay could be a contributing factor in this species-specific ability to exhibit visual plasticity. We have found that intertectal delay is 26.16 ms longer in Rana pipiens (36.53 ms) than in Xenopus laevis (10.37 ms).

Concanavalin A reduces habituation in the tectum of the frog.

In the tectum of Rana pipiens, responses to repeated flashes of light to the ipsilateral eye display considerable habituation. We have employed the plant lectin concanavalin A (Con A), which can diminish desensitization of glutamate receptors in vitro, in order to examine whether desensitization of glutamate receptors contributes to this habituation. The ipsilateral eye's projection reaches each tectal lobe indirectly, being relayed from the opposite tectal lobe via the tecto-isthmo-tectal projection. One of the sites along this pathway at which habituation may take place is the retinotectal synapse, where glutamate is a putative transmitter. Pretreatment of one lobe of the tectum with Con A significantly diminished the habituation of responses recorded in the other tectal lobe to light offset, with less of an effect on responses to light onset. These data suggest that OFF habituation may reflect glutamate receptor desensitization at the retinotectal synapse. In contrast, recordings from retinotectal terminals indicate that a primary site of habituation of ON responses is within the retina.

Acceleration by NMDA treatment of visually induced map reorganization in juvenile Xenopus after larval eye rotation.

Each tectal lobe of Xenopus frogs receives two topographic maps, one via the ipsilateral eye and one via the contralateral eye. The alignment of the ipsilateral map with the contralateral map depends upon binocular visual input during a critical period that extends from late tadpole to early juvenile stages. Rotation of one eye during the critical period leads to reorganization of the ipsilateral map, which eventually comes back into alignment with the contralateral map despite the abnormal eye position. The ipsilateral eye's map initially develops as if there had been no alteration in eye position; there is a delay of 4-6 weeks before reorganization can be detected by electrophysiological mapping. In this paper, the possible role of the NMDA receptor in the delay in reorganization is addressed. The degree of NMDA receptor activation may need to be above some threshold level to trigger reorganization. If NMDA receptor activation normally is below that level until after the first month postmetamorphosis, then exogenous NMDA might boost the process sufficiently to start the reorganization process sooner than usual. In order to test this possibility, the left eye of tadpoles was rotated and NMDA was applied to the right tectal lobe for 3-5 weeks, starting at 1 week postmetamorphosis. Electrophysiological mapping demonstrated that reorganization takes place more rapidly than in untreated frogs or frogs treated with vehicle only. This result is consistent with the interpretation that the activation of the NMDA receptor is a rate-limiting step in the activity-dependent matching of binocular maps in Xenopus tectum.

Xenopus exhibits seasonal variation in retinotectal latency but not tecto-isthmo-tectal latency.

1. The tectum of Xenopus receives visuotopic input from both eyes. The contralateral eye's projection reaches the tectum directly, via the optic nerve. The ipsilateral eye's projection reaches the tectum indirectly, via the nucleus isthmi and isthmo-tectal projection. 2. Because of the multi-synaptic nature of the ipsilateral pathway, there is an inherent delay between the time that information from the contralateral eye reaches the tectum and the time that information from the ipsilateral eye arrives at the tectum. The length of the intertectal delay is a function of the latencies of the contralateral and ipsilateral pathways. 3. The length of this intertectal delay has functional, as well as developmental, implications with regard to the role of N-methyl-D-aspartate receptors in tectal cell activity and development of orderly synaptic connections. 4. We have found that the latencies of the contralateral and ipsilateral pathways exhibit a seasonal variation, increasing during the winter months. The increases of both latencies during the winter were of similar magnitude, indicating that there were no significant changes in intertectal delay. The seasonal alteration in contralateral latency was not affected by dark-rearing and was affected to only a minor extent by a week-long alteration of ambient temperature.

Physiological effects of chronic and acute application of N-methyl-D-aspartate and 5-amino-phosphonovaleric acid to the optic tectum of Rana pipiens frogs.

Visually elicited activity contributes to the formation of orderly connections in the optic tectum of frogs. Glutamate receptors of the N-methyl-D-aspartate class participate in this process. Blocking those receptors interferes with activity-dependent refinement of maps in normal frogs and of ocular dominance bands in surgically produced animals with three eyes. Chronic application of N-methyl-D-aspartate sharpens the bands. The possibility that 5-amino-phosphonovaleric acid depresses tectal responsiveness was motivation for studying the effects of 5-amino-phosphonovaleric acid and N-methyl-D-aspartate applied both chronically and acutely. We evaluated tectal responsiveness to visual input by presenting flashes of light to one eye and recording responses in the ipsilateral tectal lobe. This method reveals the output of the tectal cells contralateral to the stimulated eye. These cells project via the nucleus isthmi to the opposite tectal lobe. We also mapped the receptive field dimensions of the crossed isthmotectal axons. Our results show that acute topical application of 500 microM or 1 mM N-methyl-D-aspartate dramatically increases spontaneous activity, while 100 microM N-methyl-D-aspartate causes little change. Chronic treatment with N-methyl-D-aspartate at a low dose (estimated to be in the micromolar range) shown to influence retinotectal mapping, reduces response latencies but produces no statistically significant changes in tectal cell firing rates or receptive field size. Acute application of 5-amino-phosphonovaleric acid produces complex results: 10 microM produces no changes in firing, 100 microM 5-amino-phosphonovaleric acid decreases firing, and doses of 500-100 microM increase the firing.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic effects of NMDA and APV on tectal output in Xenopus laevis.

In the South African clawed-toed frog Xenopus laevis, visual experience plays a crucial role in the formation of matching binocular maps in the tectum. The ipsilateral eye's projection, relayed through the crossed isthmotectal projection, displays marked plasticity in response to altered visual input during a critical period of development. This plasticity and the events responsible for the end of the critical period are mediated by N-methyl-D-aspartate (NMDA) receptor function. We have previously reported that chronic blockade of tectal NMDA receptors with the NMDA antagonist 5-amino-phosphonovaleric acid (APV) prevents plasticity of the crossed isthmotectal projection during the critical period, while chronic treatment with NMDA restores this plasticity after the end of the critical period. These results raise the question of whether the effects on plasticity are due to changes in electrical responsiveness of the treated tissue. In this study, we have quantitatively assessed the actions of APV and NMDA on certain aspects of tectal cell activity in Xenopus during and after the critical period by recording the output of the nucleus isthmi cells that are activated by the tectum after three weeks of treatment. We have found that chronic APV treatment does not alter tectal output, as indicated by the firing of isthmotectal axons, during the critical period and that chronic NMDA treatment increases tectal output in postcritical period Xenopus. Tectal output does not differ between normal Xenopus during and after the end of the critical period.(ABSTRACT TRUNCATED AT 250 WORDS)

Latency and temporal overlap of visually elicited contralateral and ipsilateral firing in Xenopus tectum during and after the critical period.

The mechanisms underlying the development of proper topographic registration of binocular maps in the tectum of Xenopus laevis involve correlation of activity patterns of ipsilateral and contralateral inputs. Recent evidence implicates NMDA-type glutamate receptors in this process. In general, NMDA receptors are considered to function optimally when there are multiple, simultaneous excitatory inputs to a dendrite. In the binocular system of the frog, however, the ipsilateral eye's response to a visual stimulus reaches the tectum later than the contralateral eye's response. The reason for this delay is that the ipsilateral pathway to the tectum is indirect, involving a relay in the opposite tectum and nucleus isthmi. In this paper, we evaluate the duration of the delay between arrival of contralateral and ipsilateral input in response to cessation of light and we also gauge the extent of temporal overlap in responses of the two inputs. We find that the average delay is about 10 ms and that this delay is not significantly different during the critical period vs later in development. The temporal overlap is 40-60 ms in duration. We conclude that the intertectal delay does not prevent a substantial period of simultaneous firing of ipsilateral and contralateral inputs in response to sudden changes in illumination. Therefore, the firing patterns of these afferents are compatible with a mechanism of activity-dependent alignment of binocular maps in the tectum.

Restoration of the plasticity of binocular maps by NMDA after the critical period in Xenopus.

Visual input during a critical period of development plays a major role in the establishment of orderly connections in the developing visual system. In Xenopus laevis, the matching of visual maps from the two eyes to the optic tectum depends on binocular visual input during the critical period, which extends from late tadpole to early juvenile stages. Alterations in eye position, which produce a mismatch of the tectal maps, normally evoke a compensatory adjustment in the map of the ipsilateral eye only during the critical period. However, continuous application of the glutamate receptor agonist N-methyl-D-aspartate (NMDA) after the normal end of the critical period restores this ability to realign the visual map.

N-methyl-D-aspartate antagonists prevent interaction of binocular maps in Xenopus tectum.

Glutamate receptors appear to play a key role in several forms of experience-dependent modification of both the strength of synapses and synaptic connectivity. In developing Xenopus frogs, the connections made by isthmotectal axons relaying visual input from the eye to the ipsilateral tectum are markedly influenced by the visual activity of contralateral retinotectal axons, and normal binocular visual input is necessary in order for the ipsilateral visuotectal map to come into register with the contralateral map. We have tested whether NMDA receptors play a role in establishment of the topographic matching of binocular maps during development. We have examined the effects of chronic treatment of tectum with either the receptor agonist NMDA or the antagonists APV or CPP applied throughout early postmetamorphic life using subpial implants of drug-impregnated elvax. Both antagonists blocked the matching of the ipsilateral map to the contralateral map, while NMDA permitted such matching. Our data therefore indicate that NMDA receptors are involved in the experience-dependent establishment of matching binocular maps during development.