Jules Baum

Basic tear flow. Does it exist

Tear flow and volume were measured in 15 normal volunteers, divided into young and old age groups, using subjective fluorophotometric analysis and Schirmer testing with and without topical anesthesia. Proparacaine 0.5% was found to anesthetize cornea and conjunctiva better than cocaine 4% and produced fewer complications. Older subjects responded to stimulation with less reflex tearing than younger subjects, but had an identical rate of physiologic tear flow, and equivalent corneal and conjunctival sensitivity. Tear flow and volume decreased significantly below physiologic values in both age groups following topical anesthetic instillation. Lid margin and cilia stimulation increased the tear turnover rate more than 300% despite adequate topical anesthesia. Flow rates determined by Schirmer testing with topical anesthesia were higher than both physiologic tear flow and tear flow following topical anesthesia when these values were determined by fluorophotometry. As sensory input was decreased, tear secretion fell correspondingly, implying that all significant tear flow results frp, reflex secretion.

Results of the Prospective Evaluation of Radial Keratotomy (PERK) Study One Year After Surgery

The Prospective Evaluation of Radial Keratotomy (PERK) study is a nine-center, self-controlled clinical trial of a standardized technique of radial keratotomy in 435 patients who had physiologic myopia with a preoperative refraction between -2.00 and -8.00 diopters. The surgical technique consisted of eight incisions using a diamond micrometer knife with blade length determined by intraoperative ultrasonic pachymetry and the diameter of central clear zone determined by preoperative refraction. At one year after surgery, myopia was reduced in all eyes; 60% were within +/- 1.00 diopter of emmetropia; 30% were undercorrected and 10% were overcorrected by more than 1.00 diopter (range of refraction, -4.25 to +3.38 D). Uncorrected visual acuity was 20/40 or better in 78% of eyes. The operation was most effective in eyes with a refraction between -2.00 and -4.25 diopters. Thirteen percent of patients lost one or two Snellen lines of best corrected visual acuity. However, all but three eyes could be corrected to 20/20. Ten percent of patients increased astigmatism more than 1.00 diopter. Disabling glare was not detected with a clinical glare tester, but three patients reduced their driving at night because of glare. Between six months and one year, the refraction changed by greater than 0.50 diopters in 19% of eyes.

Mitomycin C treatment for conjunctival-corneal intraepithelial neoplasia: a multicenter experience.

OBJECTIVE The purpose of the study is to evaluate the efficacy and risks of topical mitomycin C (MMC) for conjunctival-corneal intraepithelial neoplasia (CCIN). DESIGN The study design was a clinical case series of CCIN. PARTICIPANTS Seventeen patients, 16 with biopsy-confirmed CCIN and 1 with invasive squamous cell carcinoma (SCC), were included in the study. INTERVENTION Patients received topical drops of MMC 0.02% to 0.04% four times daily from 7 to 28 days. Retreatment was done in cases of lesion recurrence. MAIN OUTCOME MEASURES The size of the CCIN before and after the treatment and ocular complications post-MMC application were evaluated. RESULTS Ten patients remained disease-free after one course of MMC application. In one case, residual CCIN remained very small without regrowth. In the one patient with invasive SCC and in five patients with CCIN, regrowth occurred within 6 months of the first treatment. After retreatment, invasive SCC and CCIN in an additional two patients were eradicated. In two cases, although the size of the lesions decreased after two and three applications of MMC, regrowth occurred, and the CCIN returned to its original size. In the final case, limited recurrence has occurred and no retreatment has been done. The complications of MMC use included mild-to-moderate conjunctival hyperemia and mild allergy, which resolved after discontinuation of the treatment. Severe pain manifested when treatment was longer than 14 days. CONCLUSIONS Application of topical MMC is an efficient treatment for most but not all cases of CCIN.

Treatment of persistent corneal epithelial defect with extended wear of a fluid-ventilated gas-permeable scleral contact lens

PURPOSE To report treatment of persistent corneal epithelial defects unresponsive to other therapies by extended wear of a fluid-ventilated gas-permeable scleral contact lens. METHODS In this retrospective study, 14 eyes of 13 consecutive patients referred for the treatment of persistent corneal epithelial defects that failed to heal with conventional therapies or developed epithelial defects after penetrating keratoplasty for persistent corneal epithelial defects were fitted with an extended-wear gas-permeable scleral lens. These included seven eyes of six patients with Stevens-Johnson syndrome and seven eyes of seven patients who did not have Stevens-Johnson syndrome. Twelve eyes had undergone recent penetrating keratoplasty. All 14 eyes were fitted with a gas-permeable scleral contact lens designed to avoid the intrusion of air bubbles under its optic. An antibiotic and corticosteroid were added to the lens fluid reservoir or instilled before each lens insertion in 12 of 14 eyes. The lenses were worn continuously except for brief periods of removal for purposes of cleaning, replacement of the lens fluid reservoir, and examination and photography of the cornea. RESULTS Five of the seven persistent corneal epithelial defects associated with Stevens-Johnson syndrome healed. The persistent corneal epithelial defects of four of these eyes re-epithelialized within 7 days, and a fifth healed in 27 days of gas-permeable scleral lens extended wear. A sixth persistent corneal epithelial defect that failed to heal initially re-epithelialized after a subsequent penetrating keratoplasty and gas-permeable scleral lens extended wear. The seventh eye healed after 3 days of gas-permeable scleral lens extended wear, but the persistent corneal epithelial defect subsequently recurred. Three of seven non-Stevens-Johnson syndrome persistent corneal epithelial defects re-epithelialized within 36 hours, 6 days, and 36 days, respectively. Of the six (six of 14) persistent corneal epithelial defects that failed to heal with a gas-permeable scleral lens extended wear, one subsequently healed after multiple amniotic membrane grafts. Microbial keratitis occurred in four eyes (four of 14) and graft failure in one eye, all of which required repeat penetrating keratoplasty. CONCLUSION Extended wear of an appropriately designed gas-permeable scleral contact lens was effective in promoting the healing of persistent corneal epithelial defects in some eyes that failed to heal after other therapeutic measures. Re-epithelialization appears to be aided by a combination of oxygenation, moisture, and protection of the fragile epithelium afforded by the scleral lens. However, microbial keratitis represents a significant risk.

Clinically Atypical Granular Corneal Dystrophy with Pathologic Features of Lattice-like Amyloid Deposits: A Study of Three Families

Four patients from families in Pennsylvania, Massachusetts, and Argentina were diagnosed clinically as having granular dystrophy. Results of pathologic examination of the corneal buttons from each patient after penetrating keratoplasty confirmed granular deposits in the anterior third of the stroma. Amyloid was demonstrated within some of these granular deposits by Congo red staining with birefringence and dichroism and by electron microscopy. In addition to the morphologically granular deposits, numerous fusiform deposits identified as amyloid by histochemistry and electron microscopy and morphologically identical to those seen in lattice corneal dystrophy were detected deep to the granular deposits. It was further shown that the histochemical pattern of staining of the granular material by a series of lectins was similar to that present in corneas with lattice dystrophy. Although a relationship between these patients cannot be definitively proven, each family traces its origins to the Italian province of Avellino.

Initial therapy of suspected microbial corneal ulcers: I. Broad antibiotic therapy based on prevalence of organisms

The initial treatment of bacterial ulcers of the cornea should consist of a combination of antibiotics that are effective against the major pathogens in the community. A gram stain may be misleading and therefore may suggest inappropriate therapy. Antibiotic therapy should include subconjunctival injections and concentrated eye drops, but not systemic administration except following perforation. Initially, we use cefazolin and tobramycin or gentamicin. Bacitracin may be substituted as a topical medication. Antibiotic therapy should be changed only if the pathogen is reported to be resistant to initial therapy and if the corneal ulcer continues to worsen.

Transscleral iontophoresis of cefazolin, ticarcillin, and gentamicin in the rabbit.

Corneal iontophoresis produces high concentrations of drugs in the anterior segment but not in the vitreous humor of the phakic eye, presumably because transport is impeded by the lens-iris barrier. We have used two modifications to produce high levels of commonly used antibiotics in the vitreous humor of the phakic rabbit eye: the device is placed over the pars plana, circumventing the lens-iris barrier; the contact area of the column of fluid is kept small (less than or equal to 1 mm diameter) so as to provide a high current density. Applying 2 mAmp for 10 minutes, we were able to achieve mean vitreal concentrations of cefazolin, ticarcillin, and gentamicin of 94-207 micrograms/ml in the normal rabbit eye. Drug penetration showed a correlation with strength of current (0.1-2 mAmp) and with duration of iontophoresis (1-10 minutes) but not with concentration of the drug solution. Transscleral iontophoresis is a promising noninvasive technique to achieve high vitreal levels of charged solutes.

Three-year Results of the Prospective Evaluation of Radial Keratotomy (PERK) Study

The Prospective Evaluation of Radial Keratotomy (PERK) study is a nine-center clinical trial of a standardized technique of radial keratotomy in 435 patients who had simple myopia with a preoperative refractive error between -2.00 and -8.00 diopters (D). We report results for one eye of each patient. The surgical technique consisted of eight incisions using a diamond micrometer knife with the blade length determined by intraoperative ultrasonic pachymetry and the diameter of the central clear zone determined by the preoperative refractive error. At three years after surgery, 58% of eyes had refractive error within one diopter of emmetropia; 26% were undercorrected, and 16% were overcorrected by more than one diopter. Uncorrected visual acuity was 20/40 or better in 76% of eyes. The operation was more effective in eyes with a preoperative refractive error between -2.00 and -4.37 diopters. Between one and three years after surgery, the refractive error changed by 1.00 diopter or more in 12% of eyes, indicating a lack of stability in some eyes.

Bacterial Adherence to Extended Wear Soft Contact Lenses

The authors studied the adherence of Pseudomonas aeruginosa and Staphylococcus aureus to extended wear soft contact lenses (EWSCLs) with and without focal deposits using both a radiolabeling technique and electron microscopy. P. aeruginosa showed significant adherence to contact lenses in vitro. In contrast, S. aureus failed to show significant adherence to contact lenses in vitro (i.e., the radioactive uptake was not significantly above background). The extent of adherence of Pseudomonas was proportional to the number of focal deposits on the lenses. Results of electron microscopic examination showed the bacteria to be adherent primarily to large focal deposits (greater than or equal to 150 microns). There was no pseudomonal adherence to the small focal deposits (less than or equal to 50 microns) and little adherence to the areas in between the focal deposits. The authors hypothesize that worn lenses, especially those with large focal deposits, serve as a vehicle for the transport of P. aeruginosa to the cornea. This hypothesis could be a partial explanation for the high incidence of keratitis caused by P. aeruginosa in EWSCL patients.

Regional differences in ocular concentration of gentamicin after subconjunctival and retrobulbar injection in the rabbit.

We compared the penetration of radioactive carbon (14C) labeled-gentamicin into ocular tissues and fluids of albino rabbit eyes after subconjunctival (anterior subtenons) and retrobulbar (posterior subtenons) injections. In both normal and infected (Staphylococcus aureus endophthalmitis) eyes, higher levels of drug were produced with subconjunctival rather than with retrobullar admininistration in cornea, sclera, choroid and retina (as a unit), and iris; levels in the aqueous and vitreous humors of infected eyes were similar with the two routes of injection. Marked regional variations in the concentrations of gentamicin were noted in cornea, sclera, and choroid-retina after subconjunctival therapy. The pattern of these variations suggests that subconjunctival antibiotic penetrates the eye by direct diffusion. The low levels of drug after retrobulblar injection may be due to systemic absorption through the highly vascular orbital plexus of the rabbit.