Ronald M. Kurtz

ofloxacin Penetration Into The Eye After Intravenous And Topical Administration

Purpose: To determine the aqueous and vitreous fluid penetration of ofloxacin after a combined topical and single intravenous dose protocol before vitrectomy surgery. Materials and Methods: Before undergoing vitrectomy surgery, patients were given two drops of ofloxacin 0.3% topically and a single intravenous dose of ofloxacin 400 mg. Aqueous (mean, 43 minutes) and vitreous (mean, 53 minutes) fluid samples were collected at the start of the surgical procedure. The samples were analyzed for ofloxacin penetration. Results: The mean aqueous fluid concentration was 1.083 μg/mL ± 0.406. The mean ± SD vitreous fluid concentration in nondiabetic patients with intact vitreous was 0.352 μg/mL ± 0.301. Vitreous levels obtained more than 50 minutes after administration (0.414 μg/mL ± 0.336) were generally higher than those obtained after less than 50 minutes (P = 0.12). Eyes with prior vitrectomies achieved better ofloxacin penetration (0.984 μ/g/mL ± 0.680) than did nonvitrectomized eyes. Conclusion: Ofloxacin achieved measurable aqueous fluid penetration after topical and intravenous administration. Aqueous levels were above the minimum inhibitory concentration for most ocular pathogens. Vitreous levels were adequate in vitrectomized eyes to achieve inhibitory concentrations against many common ocular pathogens. Combined preoperative topical and a single dose of intravenous ofloxacin may provide inhibitory aqueous and vitreous antibiotic levels in vitrectomized eyes in cases where intravitreal antibiotics are not considered and oral administration is not practical. RETINA 17:535‐539, 1997

Femtosecond subsurface photodisruption in scattering human tissues using long infrared wavelengths

Approximately 5 million people worldwide are blind due to complications from glaucoma, and an estimated 105 million have the disease. Current surgical techniques often fail due to scarring that is associated with disruption of the ocular surface tissues using conventional surgical methods. Demonstrated in the transparent cornea, femtosecond lasers can create a highly precise incision beneath the surface of a tissue. Since sclera is highly scattering with one micron light, the same wavelength used in cornea cannot be focused to the small spot necessary for photodisruption far beneath the surface of sclera. We now demonstrate completely subsurface incisions in human sclera by selecting a laser wavelength that is focusable beneath the surface, namely 1700 nm. Similar techniques may be used in other translucent tissues such as skin. Subsurface femtosecond photodisruption may be a useful for in vivo surgical technique to perform a completely subsurface surgery.

Accuracy of Digital Images for Assessing Diabetic Retinopathy

Background: To determine the accuracy of diabetic retinopathy status assessments with and without pupil dilation using digital fundus photographs acquired by a clinic staff person and interpreted remotely by ophthalmologists. Method: Using early treatment diabetic retinopathy study (EDTRS) grading criteria, diabetic retinopathy status assessments were made by an experienced (nonphysician) retinal grader (NPG) based on seven standard field 35-mm stereoscopic slides acquired by an experienced ophthalmic photographer. These assessments were compared with those of the same eyes made by two ophthalmologists and the NPG using digital photographs acquired by a clinic staff person using a high-resolution (800 × 600) digital color camera system. Results: Based on 35-mm slides, 38% of 244 diabetic patients had ETDRS >35 in at least one eye and 5% had vision-threatening diabetic retinopathy (ETDRS >53 or macular edema). The proportion of ungradable images was significantly greater for nonmydriatic than mydriatic assessments (30% versus 10% ungradable as determined by the NPG). For ETDRS level >35, specificity ranged from moderate to high (0.70 to 0.96) for the three graders, while sensitivity was poor to moderate (0.38 to 0.71), and the area under the receiver-operating characteristic curves was less than satisfactory (0.67 to 0.71). Conclusions: The low sensitivity of the digital assessments indicates a significant proportion of patients in need of referral would not have been referred. These findings suggest that implementation of a simplified screening system using nonphotographer clinic staff acquiring nonmydriatic images, with interpretation by an ophthalmologist, should take place with an understanding of potential limitations.

Femtosecond Lasers for Ultra-Accurate Surgery: Application to Corneal Surgery

We investigated refractive corneal surgical procedures utilizing amplified femtosecond laser pulses from a reliable and compact femtosecond laser system suited for medical applications. Procedures such as corneal flap cutting and laser keratomileusis have been demonstrated in vivo and in vitro. Cutting was found to be well confined and highly precise.