Kenneth L. Cohen

Effect of Trephine Tilt on Corneal Button Dimensions

Wound disparity, mismatch between the size and shape of the donor corneal button and its wound, probably determines the direction and amount of postkeratoplasty astigmatism. Tilting a hand-held trephine is thought to contribute to an oval wound and to wound disparity. We examined the contribution of trephine tilt to wound size and shape. Eyebank eyes were hand trephined at 0, 5, 10, 15, 20, and 25 degrees of tilt. The button endothelial edges were analyzed by the photogrammetric index method. All index values were significantly different from those for a theoretically circular or symmetric button. Although the most oval buttons were at 20 and 25 degrees, buttons were similarly oval and asymmetric for trephine tilt from 0 to 15 degrees. Neither ovality nor asymmetry correlated with angle of tilt. Even when no attempt is made to tilt a hand-held trephine, oval and irregularly shaped wounds may result.

Mucinous sweat gland adenocarcinoma of the eyelid

A 62-year-old woman developed a recurrent mucinous sweat gland adenocarcinoma of the eyelid. The clinical characteristics of this rare, primary adnexal neoplasm of skin in our patient were, to our knowledge, unique. The tumor mimicked a lacrimal sac tumor and had orbital extension demonstrated preoperatively by computed axial tomography. Orbital extension of the tumor mass was confirmed during a wide, en bloc, excisional biopsy.

Automatic quantitative measurement of ocular hyperemia

Evaluation of ocular hyperemia has been an important assessment in research studies of effects of contact lenses, medications, and pollutants on the eye. Hyperemia has been difficult to quantitate objectively. The purpose of this study was to validate a computer based image analysis system to quantitate hyperemia automatically and objectively in pixelated images of the external eye using two measures, the percent of the red color, RR, and the fraction of pixels which are blood vessels, VA. Validation was against an established photographic reference scale of ocular hyperemia and against the clinical pharmacologic effects of 0.5% dapiprazole hydrochloride, known to increase hyperemia, and 2.5% phenylephrine hydrochloride, known to decrease hyperemia. Color transparencies from the reference scale were converted to digital images. Temporal and nasal regions of the external eye were imaged directly to magnetic disk before and after pharmacologic intervention. Custom software automatically excluded unwanted regions, and quantitative image analysis produced RR and VA. RR and VA were each correlated with the reference scale. For each region and for each pharmacologic intervention, the mean RR and the mean VA, respectively, were compared at time zero and at a mean elapsed time of 713 +/- 47 s. RR and VA consistently increased as the hyperemia in the reference scale increased. Pearson correlation coefficients were 0.98 and 0.99, respectively, (p < 0.01). At 713 +/- 47 s after each pharmacologic intervention, RR and VA increased and decreased as expected (p < 0.001). Thus, this study successfully validated the methodology against expert clinical judgment and was able to measure automatically and objectively clinical changes in ocular hyperemia.

Sulfur hexafluoride gas in the repair of Descemet's membrane detachment

We report a case of successful attachment of a detached Descemets membrane using an intracameral injection of sulfur hexafluoride (SF6). Three months after cataract surgery, a 77-year-old woman was seen for almost total detachment of Descemets membrane. Surgical repair with a through-and-through mattress suture was unsuccessful. One month later, Descemets membrane was apposed by injecting 0.25 ml of 100% SF6 into the anterior chamber. Six months later the central corneal thickness measured 0.48 mm, and Descemets membrane was attached. We believe this to be the first reported case of successful attachment of Descemets membrane using an intracameral injection of 100% SF6.

Identification of unknown intraocular material after cataract surgery: Evaluation of a potential cause of toxic anterior segment syndrome

PURPOSE: To describe and identify unknown opaque material between the optic of an AR40 intraocular lens (IOL) injected with the Emerald Series implantation system (both AMO, Inc.) and the posterior capsule at the conclusion of routine phacoemulsification to prevent an outbreak of toxic anterior segment syndrome (TASS). SETTING: Ambulatory care center operating room, University of North Carolina Hospitals and Department of Ophthalmology, University of North Carolina School of Medicine at Chapel Hill, Chapel Hill, North Carolina, USA. METHODS: After coaxial phacoemulsification in multiple patients, opaque material was present between the optic of a posterior chamber IOL and the posterior capsule. Although there was no TASS, the material was removed from 2 eyes and analyzed with scanning electron microscopy (SEM) and x‐ray microanalysis (XRM). Similarly, crystalline lens, Klenzyme (Steris Corp.), Viscoat (sodium hyaluronate 3.0%–chondroitin sulfate 4.0%), and Provisc (sodium hyaluronate 1.0%) were analyzed. RESULTS: On SEM, the material had an irregular undulating surface similar to that of Provisc. Viscoat and the crystalline lens had smoother surfaces. On XRM, the material contained sodium, chlorine, and calcium, like Viscoat and Provisc, and phosphorous and sulfur, like Viscoat. The material also contained silicone, magnesium, aluminum, titanium, iron, and zinc. Klenzyme had smaller peaks of sodium, chlorine, and calcium and a higher carbon background than the unknown material. CONCLUSIONS: The material was likely ophthalmic viscosurgical device that was chemically and structurally altered by the cleaning and sterilization process. The silicone and metallic elements were probably from the Emerald Series implantation system as the disposable cartridge is coated with silicone and the reusable injector is metal.

Sarcoidosis of the Eyelid Skin

PURPOSE/METHODS A 34-year-old woman with a history of pulmonary sarcoidosis was referred for examination and treatment of suspected molluscum contagiosum nodules of the eyelids. After full ophthalmic examination, she underwent a biopsy of an eyelid nodule. RESULTS/CONCLUSIONS Histopathologic examination of the eyelid nodule showed numerous, noncaseating granulomas as well as giant cells. This case represents the rare findings of sarcoidosis of the eyelid skin in a patient with chronic but not ocular sarcoidosis.

Aeromonas Hydrophila and Plesiomonas Shigelloides Endophthalmitis

Aeromonas hydrophila and Plesiomonas shigelloides are gram-negative, facultatively anaerobic rod-like bacteria. Both organisms have a reputation for low virulence in humans. Only recently have two corneal ulcers, one case of posttraumatic endophthalmitis, and two possible conjunctival infections caused by A. hydrophila been reported. 1-3 To our knowledge, there have been no reports of P. shigelloides ocular infections. We treated a case of posttraumatic endophthalmitis caused by A. hydrophila and P. shigelloides.

Determining factors for corneal endothelial cell loss by using bimanual microincision phacoemulsification and power modulation.

Purpose: To determine risk factors for central corneal endothelial cell loss in bimanual microincision cataract surgery by using power modulation. Methods: Prospective study: 79 eyes (70 subjects) with uncomplicated bimanual cataract surgery by using power modulation. Cataracts were graded with the LOCS III system. Specular microscopy was performed preoperatively and postoperatively (5 weeks). Endothelial cell density was calculated (CD; cells/square millimeter). Endothelial cell loss (ECL = preoperative CD − postoperative CD; cells/square millimeter) and proportional loss of cells [PLC = (ECL/preoperative CD) × 100; %)] were calculated. Phacoemulsification time (seconds) and average phacoemulsification power in foot position 3 (%) were recorded. Results: Cataracts were moderate to high density, nuclear color = 3.96, and nuclear opalescence = 3.91. Endothelial cell loss = 196 cells/square millimeter (P < 0.0001). Proportional loss of cells = 8.12% (P < 0.0001). Average phacoemulsification power in foot position 3 was low (8.17%). Increased nuclear color and opalescence were correlated with more phacoemulsification time and higher average phacoemulsification power in foot position 3 (P < 0.0001). Endothelial cell loss and proportional loss of cells, respectively, were affected by increased nuclear color (P < 0.004, P < 0.003) and opalescence (P < 0.006, P < 0.004) but were not affected by phacoemulsification time. Average phacoemulsification power in foot position 3 had a mild effect on endothelial cell loss and proportional loss of cells (P = 0.02, P = 0.02). Conclusions: Despite the need for longer phacoemulsification time and increased power to emulsify denser cataracts, the amount of endothelial cell loss was only mildly affected by the average phacoemulsification power in foot position 3 and unaffected by total phacoemulsification time, showing that bimanual phacoemulsification with power modulation is an efficient and effective technique for performing cataract surgery.

Aqueous Vascular Endothelial Growth Factor as a Predictor of Macular Thickening Following Cataract Surgery in Patients With Diabetes Mellitus

PURPOSE To study associations between serum and aqueous vascular endothelial growth factor (VEGF) and insulin-like growth factor 1 (IGF-1) and macular edema measured with optical coherence tomography (OCT) following phacoemulsification in diabetic patients. DESIGN Cohort study. METHODS A pilot study of 36 consecutive diabetic patients undergoing planned phacoemulsification with IOL in 1 eye by one surgeon at the University of North Carolina consented to preoperative and postoperative OCT central subfield (CSF) thickness measurements and aqueous and blood samples for VEGF and IGF-1. Four patients with clinically significant macular edema (CSME) received laser preoperatively. Spearman-rank correlations were performed between growth factors and mean CSF or a clinically meaningful percent change in CSF (>11% of preoperative measurement) at 1 and 6 months postoperatively. RESULTS There were no surgical complications or new cases of CSME following surgery. Mean aqueous VEGF in patients with retinopathy, determined preoperatively, increased with increasing level of severity. Patients with preoperative CSME also had severe or worse retinopathy and the greatest mean aqueous VEGF. Significant preoperative correlations existed between aqueous VEGF and more severe retinopathy whether CSME was present or absent (r = 0.49; P = .007), and between aqueous VEGF and CSME (r = 0.41; P = .029). At 1 month postoperative, aqueous VEGF was positively correlated with >11% change from preoperative CSF regardless of CSME status (r = 0.47; P = .027). No noteworthy associations existed between CSF and IGF-1 values. CONCLUSIONS Aqueous VEGF was significantly positively associated with a clinically meaningful change in CSF in diabetic patients 1 month following cataract surgery. Accounting for preoperative CSF was important. Further study is indicated.

Topical ciprofloxacin versus topical fortified antibiotics in rabbit models of Staphylococcus and Pseudomonas keratitis

We tested the antibacterial activity of ophthalmic 0.3% ciprofloxacin against that of 5.0% cefazolin and 1.36% tobramycin in two experimental models of keratitis, using a methicillin-sensitive strain of Staphylococcus aureus and an aminoglycoside-sensitive strain of Pseudomonas aeruginosa, respectively. Both corneas of New Zealand white rabbits were intrastromally injected with either S. aureus or P. aeruginosa. Twenty-four hours later, each eye was topically treated hourly for 24 hours. In the S. aureus model, the control group received Tears Naturale Free (Alcon Laboratories, Inc., Fort Worth, TX), the ciprofloxacin group received 0.3%, ciprofloxacin and the cefazolin group received 5.0% cefazolin. In the P. aeruginosa model, the control group received Tears Naturale Free, the ciprofloxacin group received 0.3% ciprofloxacin, and the tobramycin group received 1.36% tobramycin. One hour after the last eyedrops were administered, the rabbits were killed, and their corneas were processed for quantification of bacteria. For the S. aureus model, the mean (±SEM) colony forming units (CFU) of the control, 7.1 x 106 (±4.0 x 106); ciprofloxacin, 6.4 x 102 (±1.6 x 102); and cefazolin, 1.3 x 103 (±1.8 x 102) groups were different (F=17.5; p=0.001). The ciprofloxacin and cefazolin groups were not different from each other (p=0.034). The mean (±SEM) CFU for the control group in the P. aeruginosa model was 2.8 x 108 (±1.7 x 107). All corneas in the ciprofloxacin and tobramycin groups were sterile. Short-term treatment with ciprofloxacin was an effective treatment when compared with both fortified cefazolin and fortified tobramycin in eradicating S. aureus and P. aeruginosa, respectively, in these rabbit models of bacterial keratitis.