Macular thickness mapping in exudative age-related macular degeneration.

PURPOSE: To report the feasibility of retinal thickness mapping for evaluating thickness differences in retinal areas with and without leakage shown by fluorescein angiography for patients who have age-related macular degeneration with choroidal neovascularization. METHODS: A custom-built version of the retinal thickness analyzer was used for thickness mapping. Retinal thickness was defined as the separation between vitreoretinal and pigment epithelium-choroid interfaces. Imaging was performed in 1 eye of 10 patients with the clinical diagnoses of age-related macular degeneration and choroidal neovascularization. Patients either had never undergone photodynamic therapy at the time of measurement (untreated) or had received one or more photodynamic therapy treatments (treated). Average retinal thicknesses in selected areas with and without the presence of leakage shown by fluorescein angiography were calculated and compared statistically. RESULTS: Retinal thickness (mean +/- SD) in areas with leakage (315 +/- 54 microm) was significantly greater than that in areas without leakage (280 +/- 28 microm) (P = 0.03). In untreated patients, areas with leakage (345 +/- 45 microm) were significantly thicker than areas without leakage (289 +/- 23 microm) (P = 0.02). In treated patients, retinal thickness in areas with leakage (271 +/- 33 microm) and without leakage (267 +/- 34 microm) was similar. CONCLUSION: Retinal thickness mapping may prove to be useful as an adjunct to fluorescein angiography to monitor choroidal neovascularization and its treatment.

Retinal topography and thickness mapping in atrophic age related macular degeneration.

AIM: To determine the relation between alterations in the retinal topography and thickness, visual acuity, and retinal pigment epithelium hypopigmentation in atrophic age related macular degeneration (AMD). METHODS: 22 patients, mean age 74 (SD 8) years, with atrophic AMD were recruited. An optical imaging system based on the retinal thickness analyser (RTA) was applied to generate a series of 20 optical section images that encompass 2 mm x 2 mm retinal areas. The optical section images were digitised and analysed to provide topographic maps of the vitreoretinal and chorioretinal surfaces and the retinal thickness. Vitreoretinal and chorioretinal surface elevations and retinal thickness were determined. RESULTS: Variation in the vitreoretinal surface height was moderately correlated with visual acuity (r = -0.4; p = 0.03; n = 22). Increase in variation of chorioretinal surface height was correlated with decrease in visual acuity (r = -0.5; p = 0.01; n = 22). The retinal thickness was not associated with visual acuity (r = 0.2; p = 0.2; n=22). Relative height of the vitreoretinal surface in eyes with retinal pigment epithelium (RPE) hypopigmentation was significantly less than eyes without RPE hypopigmentation (p = 0.005). Eyes with and without RPE hypopigmentation had a similar relative height of the chorioretinal surface (p = 0.4). Retinal thickness in eyes with RPE hypopigmentation was less than in eyes without RPE hypopigmentation (p = 0.04). CONCLUSION: Mapping of chorioretinal and vitreoretinal topography and retinal thickness provides objective and quantitative measurements of retinal structural abnormalities and shows promise as an adjunct for the evaluation of retinal structural changes due to AMD.

Findings on retinal topography and thickness mapping in age-related macular degeneration.

PURPOSE: To report alterations in the retinal topography and thickness in typical cases of age-related macular degeneration (ARMD). METHODS: An optical imaging system was applied to patients with ARMD with alterations in the retinal structures. The system generates a series of 20 optical section images that encompass a 2 mm x 2 mm retinal area. The optical sections are digitized and analyzed to provide topographic maps of the vitreo-retinal and chorio-retinal surfaces and the retinal thickness. RESULTS: Retinal topography and thickness mapping in a normal eye corresponded to normal anatomy. Topographic mapping in a patient with confluent drusen indicated elevation of the vitreo-retinal surface. Retinal topography in a patient with retinal pigment epithelium detachment displayed localized elevation of the chorio-retinal surface. The thickness map in a patient with geographic atrophy of the retinal pigment epithelium revealed retinal thinning. In the patients with choroidal neovascularization, the vitreoretinal and chorio-retinal surfaces were elevated. The chorio-retinal surface map in a patient with evolving disciform scar displayed topographic variations corresponding to the fibrovascular tissue underlying the serous detachment. CONCLUSION: Retinal topography and thickness mapping is useful for visualization and evaluation of pathologic alterations in retinal structures due to ARMD.

Aqueous and vitreous penetration of levofloxacin after oral administration.

OBJECTIVE: To investigate the penetration of levofloxacin, an optical S-(-)isomer of ofloxacin, into the aqueous and vitreous humor after oral administration. DESIGN: Randomized, clinical trial comparing tissue levels of levofloxacin after one or two doses 12 hours apart. PARTICIPANTS: Forty-five patients undergoing initial vitrectomy between February 1997 and June 1997 at the UIC Eye Center. METHODS: Aqueous, vitreous, and serum samples were obtained and later analyzed from 45 patients after oral administration of 1 500-mg tablet (group 1, 22 patients) or 2 500-mg tablets (group 2, 23 patients) 12 hours apart before surgery. MAIN OUTCOME MEASURES: Aqueous, vitreous, and serum concentrations of levofloxacin (micrograms/milliliter). RESULTS: Group 1 achieved mean aqueous, vitreous, and serum levels of 0.59 +/- 0.48 microg/ml, 0.32 +/- 0.34 microg/ml, and 4.34 +/- 3.59 microg/ml, respectively. Group 2 achieved mean aqueous, vitreous, and serum levels of 1.90 +/- 0.97 microg/ml, 2.39 +/- 0.70 microg/ml, and 8.02 +/- 3.14 microg/ml. CONCLUSIONS: Mean inhibitory aqueous and vitreous MIC90 levels were achieved against a majority of ocular pathogens, including Staphylococcus aureus and Staphylococcus epidermidis, Streptococcus pneumoniae (vitreous), Bacillus cereus (vitreous), Haemophilus influenzae, Moraxella catarrhalis, and most gram-negative aerobic organisms except Pseudomonas aeruginosa after two doses given 12 hours apart. Mean MIC90 levels were obtained in the vitreous for a majority of pathogens responsible for traumatic, postoperative, or bleb-related endophthalmitis.

Outcome of vitreoretinal surgery and penetrating keratoplasty using temporary keratoprosthesis.

PURPOSE: The use of a temporary keratoprosthesis has allowed earlier surgical intervention in eyes with coexisting vitreoretinal and corneal disease. We analyzed our experience with this type of surgery. METHODS: We retrospectively reviewed charts of patients in whom a temporary keratoprosthesis was used between 1987 and 1998. Analysis was focused on ocular history, indications for surgery, visual acuity (VA), intraocular pressure, anatomic results, and complications. RESULTS: A temporary keratoprosthesis was used in 31 eyes, 22 (71.0%) of which were for trauma-related indications. In 6 (19.4%) of the operated eyes, the fellow eye also had severely reduced VA. Retinal detachments were present in 30 (96.8%) eyes; most had evident proliferative vitreoretinopathy. Twelve (38.7%) eyes had vitreous hemorrhage, and 20 (64.5%) had corneal scars. Improvement in VA was seen initially in 45.1% of patients, and 51.6% maintained equal or better VA at their final visit as compared with before surgery. The common documented reasons for poor final VA were recurrent retinal detachments deemed inoperable (32.3%), phthisis (22.6%), and optic atrophy or macular scar (16.1%). Corneal grafts remained clear in 41.9%. Nine patients had further surgery. The most significant complication was one case of sympathetic ophthalmia. CONCLUSIONS: Combined vitreoretinal and corneal surgery using temporary keratoprostheses has been used in our institution to treat eyes with extreme abnormalities. Outcomes were less favorable than some reported in the literature, probably because of the severity of disease for which temporary keratoprostheses were reserved. Although results are probably better than the natural course of the disease, patients should be informed of realistic expectations for improvement and potential complications when offered this option.

Intraocular penetration of gentamicin after once-daily aminoglycoside dosing.

BACKGROUND: Intraocular concentrations-particularly intravitreal concentrations-after systemic administration of gentamicin are poor. Once-daily aminoglycoside dosing of intravenous gentamicin achieves peak serum levels up to five times higher than conventional dosing. Whether these increased serum levels of gentamicin improve the aqueous or vitreous concentrations in humans has not been determined. The authors sought to determine if the intraocular penetration of gentamicin would be improved using this method. METHODS: Patients undergoing vitrectomy procedures were administered intravenous gentamicin in a dose of 7 mg/kg approximately 1 hour before surgery. An adjustment in dosing was made for anyone more than 20% over his or her ideal body weight. Aqueous, vitreous, and serum samples were collected before any intraocular surgical manipulation. The samples were analyzed by fluorescence polarization immunoassay (TDx system). RESULTS: The average single gentamicin dose was 498 mg (range, 360-700 mg). The aqueous, vitreous, and serum levels averaged 1.14 microg/mL, 0.41 microg/mL, and 22.07 microg/mL, respectively. No correlation between serum level concentrations and time of administration was found for the aqueous and vitreous levels in this study. CONCLUSION: Although the average peak serum level of gentamicin was five times higher than previously reported, the vitreous levels averaged only 1.5 times higher. The blood-retinal barrier is difficult to penetrate even when higher serum levels are achieved. Due to its poor ocular penetration, gentamicin may not be among the best drugs for prophylaxis of penetrating eye injuries, surgical prophylaxis, or treatment of endophthalmitis.

Clinical assessment of the macula by retinal topography and thickness mapping.

PURPOSE: To report a quantitative and objective method for assessing pathologic alterations in retinal structures to improve the evaluation of macular diseases. METHODS: We used a system based on the scanning retinal thickness analyzer to generate serial optical section images of the retina and provide mapping of the retinal topography and thickness in a normal subject and in patients with representative maculopathies including traumatic macular hole, central serous chorioretinopathy, branch retinal vein occlusion, diabetic macular edema, and retinal pigment epithelial detachment. RESULTS: The effectiveness of the system in imaging both the vitreoretinal and chorioretinal interfaces was confirmed in the normal subject and in patients with various maculopathies. Mapping of retinal topography and thickness in a normal eye correlated well with normal anatomy, delineating the foveal depression clearly. The retinal thickness map in a patient with diabetic macular edema showed thickening of the retina and absence of a foveal depression. The patients with central serous chorioretinopathy and branch retinal vein occlusion had an elevated vitreoretinal surface. Conversely, the patient with retinal pigment epithelial detachments had a relatively flat vitreoretinal interface but an irregularly elevated chorioretinal surface. CONCLUSION: Quantitative mapping of retinal topography and thickness is a promising tool that may improve evaluation of macular diseases.

Influence of the cannulated vitrectomy system on the occurrence of iatrogenic sclerotomy retinal tears.

PURPOSE: To determine whether the use of the cannulated vitrectomy system decreases the incidence of sclerotomy-related retinal tears relative to traditional vitrectomy techniques. METHODS: Forty-one eyes of 77 patients in this study were randomly selected to undergo treatment with the cannulated port system. RESULTS: We demonstrated a statistically significant decreased incidence of sclerotomy tears in the cannulated group relative to the noncannulated group (1% vs. 7.7%, P < 0.05). The benefit of the cannulated port system appears to be greatest in cases in which an inexperienced surgeon is learning the techniques of vitreoretinal surgery, in eyes with a preoperative diagnosis of tractional diabetic detachment, and in surgery requiring membrane delamination (simple and extensive). CONCLUSION: The three-port vitrectomy system decreases the incidence of sclerotomy-related retinal tears.

Knowledge or noise. Scientific publication and the electronic journal.

Over the last few years, the Internet has grown exponentially and is developing a role in the exchange of scientific information. However, a number of problematic issues are associated with electronic publications, including limited transmission speed, undependable file longevity, poorly documented postpublication editing, copyright infringement, and cultural impediments to acceptance. By measure of citation frequency, electronic journals seem to have limited influence within scientific discourse, but this medium is as yet in its infancy. Since electronic publication enjoys many potential advantages over traditional print publication, it is expected to gain far greater influence over time. The American Medical Association group of publications recognizes this and intends to develop its electronic publications with attention to maintaining traditional critical scientific standards.

Aspartate separation of the scotopic threshold response (STR) from the photoreceptor a-wave of the cat and monkey ERG.

We recorded ERG responses at the cornea of cat and monkey and identified the initial negative wave elicited by very dim stimuli as the scotopic threshold response (STR) comparable to that previously recognized by intraretinal recordings of cat. The STR, but not the photoreceptor a-wave, was eliminated by intravitreal aspartate in both cat and monkey, which demonstrated that the STR origin was post-photoreceptoral. Intraretinal recordings before and after aspartate confirmed that the a-wave of cat with bright light was fast-PIII from photoreceptors, and further showed that there was minimal or no extracellular activity recordable near the photoreceptors with very dim stimuli after aspartate. This study showed practical ways to separate the STR from the photoreceptor a-wave in corneal records, by the range of stimulus intensity (STR with dim stimuli; photoreceptor a-wave with bright stimuli) and by response latency (STR, long latency; photoreceptor a-wave, short latency). These recordings provide the first evidence that the monkey has an STR, and that it is post-photoreceptoral like the STR of cat. Further, this provides support to consider that the corneal negative STR wave of the human ERG with dim light may also be post-photoreceptoral.