Jon P. Gieser

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.

Localized retinal dysfunction in central serous chorioretinopathy as measured using the multifocal electroretinogram

PURPOSE To determine the extent of electrophysiologic dysfunction in patients with central serous chorioretinopathy (CSC). DESIGN Prospective observational case series. PARTICIPANTS Six patients with unilateral CSC (mean age, 40 years) were recruited into the study. METHODS Six patients with CSC underwent multifocal electroretinogram (mfERG) testing on both their clinically affected and opposite uninvolved eyes using the VERIS System, with a stimulus array of 103 scaled hexagons. The first positive peak responses were analyzed within six concentric ring annuli centered on the fovea. Amplitudes and implicit times were compared with those of an age-similar control group. MAIN OUTCOME MEASURES Local electroretinographic response amplitudes and implicit times within the central 40 degrees with the mfERG. RESULTS All the clinically uninvolved eyes showed mfERG amplitudes and implicit times within the normal range throughout the central 40 degrees of the retina. All six eyes with CSC showed reduced amplitudes and/or delayed implicit times that were limited to the regions of the macula in which clinical changes associated with CSC were apparent. CONCLUSIONS We observed electroretinographic changes only in the clinically affected eyes, and these were limited to regions with ophthalmoscopically apparent fundus changes. Our findings do not support the conclusion that functional impairment, as measured by the mfERG, in eyes with CSC extends beyond clinically observed fundus changes. We did not observe abnormal mfERG responses in the clinically normal eyes of such patients.

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 sclerotomyrelated retinal tears. RETINA 17:430‐433, 1997

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.

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 μg/mL, 0.41 μg/mL, and 22.07 μg/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.

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 × 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 vitreo-retinal 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.

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 × 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.

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 &mgr;m) was significantly greater than that in areas without leakage (280 ± 28 &mgr;m) (P = 0.03). In untreated patients, areas with leakage (345 ± 45 &mgr;m) were significantly thicker than areas without leakage (289 ± 23 &mgr;m) (P = 0.02). In treated patients, retinal thickness in areas with leakage (271 ± 33 &mgr;m) and without leakage (267 ± 34 &mgr;m) was similar. Conclusion: Retinal thickness mapping may prove to be useful as an adjunct to fluorescein angiography to monitor choroidal neovascularization and its treatment.