Intraocular lens power calculation after laser in situ keratomileusis for myopia and hyperopia: a standardized approach.

PURPOSE: (1) To determine the effect of myopic and hyperopic laser in situ keratomileusis (LASIK) on calculation of intraocular lens (IOL) power. (2) To determine a standard way to approach the IOL power determination after LASIK, and (3) To compare different suggested methods. METHODS: Biometric analysis and theoretical calculation of IOL powers for eyes undergoing LASIK for myopia and hyperopia were performed. RESULTS: Manual keratometry after LASIK for myopia resulted in underestimation of IOL power. Manual keratometry after hyperopic LASIK resulted in overestimation of IOL power. The amount of error was directly related to the amount of correction by LASIK. CONCLUSION: The pre-LASIK refraction can be used theoretically to determine an accurate IOL power.

Superficial hypertrophic dendriform epitheliopathy post-keratoplasty.

PURPOSE: To describe a distinct and unusual superficial dendriform keratopathy that can be seen in postkeratoplasty eyes. METHOD: Three Caucasian women in their sixth decade of life were referred to the Corneal and External Disease Service at the University of California, Davis, and underwent penetrating keratoplasty for different diagnoses. After keratoplasty, hypertrophic dendriform epithelial lesions were observed. These were refractory to debridement as well as topical antibiotic and steroid combinations. Immunofluorescent antibody testing was performed in all cases to rule out herpetic infection, and the patients were treated with nonpreserved lubricants and medications to eliminate medication toxicity as the cause of the lesions. RESULTS: All three patients in this series developed raised, hypertrophic epithelial lesions after keratoplasty, which were refractory to therapy. Comfort and mild increase in visual acuity were restored with the use of thin, moderate water content therapeutic contact lenses. CONCLUSIONS: Superficial hypertrophic dendriform epitheliopathy is a distinct syndrome that occurs postkeratoplasty in patients with preexisting chronic ocular inflammation, tear dysfunction, and/or lid disease exacerbated by the toxic effects of postoperative topical medication.

In vitro and in vivo effects of polyhexamethylene biguanide against herpes simplex virus infection.

PURPOSE: The differential diagnosis of Acanthamoeba keratitis frequently includes herpes simplex viral keratitis. Previous in vitro studies with chlorhexidine, a drug with antiacanthamoebic action, have suggested concomitant antiviral activity against herpes simplex virus. We tested another related antiacanthamoebic compound, polyhexamethylene biguanide (PHMB), to determine its activity against herpes simplex virus (HSV) in vitro and herpes simplex viral keratitis in vivo. METHODS: Equal aliquots of HSV-1 (McKrae) strain were incubated in a medium with no PHMB or with PHMB at 0.01, 0.02, or 0.05 for 5 min at 35 degrees C and the inoculum was then titered on a monolayer of E-2 cells (human corneal fibroblasts). Monolayers were examined on consecutive days and the percentage of plaque reduction was calculated. Eighteen rabbits (36 eyes) were inoculated with HSV-1 McKrae strain (10(5) pfu [plaque-forming units]/per eye). Rabbits were divided into three groups and treatment was initiated on day 3 postinfection. Group I received trifluorothymidine, group II received PHMB, and group III received artificial tears, each given five times daily in both eyes until day 10. Daily corneal swabbing to detect viral shedding and slit-lamp examination every 3 days were performed during this period. RESULTS: In vitro studies showed 62.5, 100, and 100% plaque reduction with 0.01, 0.02, and 0.05% PHMB, respectively. Slit-lamp examination of the rabbit corneas revealed faster resolution of dendrites in animals in group I treated with trifluorothymidine. Virus was not recoverable from corneal swabs in nine of 10 rabbits in group I by day 5, but all animals in groups II and III were still shedding HSV through day 8. CONCLUSION: Although PHMB has potent in vitro activity against HSV, it was not an effective treatment in the in vivo rabbit model of primary HSV keratitis at the concentration commonly used for treatment of Acanthamoeba infection. This suggests that 0.02% PHMB will not provide adequate antiherpetic coverage with treatment of keratitis of undetermined etiology in which the clinical differential diagnosis includes both herpes simplex and Acanthamoeba.

Screening corneas for human immunodeficiency virus type 1 proviral DNA by polymerase chain reaction.

PURPOSE: We evaluated the sensitivity of the polymerase chain reaction as a technique to directly screen potential donor corneas for human immunodeficiency virus type 1 (HIV-1) proviral DNA. METHODS: DNA from the central 8.0-mm cornea, limbal cornea, aqueous humor, and retina from 22 eyes of 11 cadavers seropositive for HIV was extracted and amplified by polymerase chain reaction using primers specific for the gag and env regions of the HIV-1 genome. The identity of amplification products was confirmed by Southern blot hybridization. RESULTS: Viral DNA was detected in four (18.2%) of 22 central corneas, one (4.5%) of 22 limbal corneas, one (6.3%) of 16 aqueous humor samples, and seven (31.8%) of 22 retinas. No correlation was noted between the presence of HIV-1 proviral DNA in samples from the central cornea and from the other tissues tested from the same eye. CONCLUSIONS: Within the limits of our assay, processing and analysis of limbal cornea, aqueous humor, and retina by polymerase chain reaction may not reliably ascertain the presence of HIV-1 in the central, transplantable cornea.

Comparative diagnosis of neonatal chlamydial conjunctivitis by polymerase chain reaction and McCoy cell culture.

Cervical and ocular swabs from 100 mother/newborn pairs delivering on the clinic service were assayed for Chlamydia trachomatis with standard McCoy cell culture and with standard and biotinylated polymerase chain reaction techniques, using primers directed against the major outer membrane protein gene and C. trachomatis-specific cryptic plasmid, respectively. Using the polymerase chain reaction, 20 (20%) mothers and seven (7%) neonates were positive for Chlamydia. All neonates positive by polymerase chain reaction were from mothers positive by polymerase chain reaction, yielding a 35% transmission rate. Only five of 20 (25%) mothers and two of seven (28%) neonates positive by polymerase chain reaction were positive by cell culture. All cell culture samples were positive by polymerase chain reaction testing. Culture and polymerase chain reaction analysis two weeks after treatment with oral erythromycin were negative. The polymerase chain reaction assay appears to be equally specific and more sensitive than McCoy cell culture for the detection of C. trachomatis from ocular specimens.

The use of polymerase chain reaction for the detection of chlamydial keratoconjunctivitis.

Ocular swabs from 30 consecutive patients with follicular conjunctivitis were screened for Chlamydia trachomatis, herpes simplex virus, and adenovirus by a variety of laboratory techniques. For the detection of C. trachomatis, we compared two polymerase chain reaction methods, McCoy cell culture isolation, and the direct fluorescein-conjugated monoclonal antibody test. Four of 30 patients tested positive for C. trachomatis by using both conventional and biotinylated polymerase chain reaction methods. Two of the four patients were also McCoy cell culture-positive for C. trachomatis and one of four patients tested positive by using a fluorescein-conjugated chlamydial monoclonal antibody test. All four patients responded to oral antibiotic treatment. On follow-up testing, all four patients were polymerase chain reaction-negative, McCoy cell culture-negative, and fluorescein-conjugated antibody test-negative for C. trachomatis. The polymerase chain reaction appears to be an equally specific and more sensitive method than McCoy cell culture or fluorescein-conjugated antibody testing for the detection of C. trachomatis from ocular specimens.

Antimicrobial efficacy and corneal endothelial toxicity of DexSol corneal storage medium supplemented with vancomycin.

Despite the presence of gentamicin in corneal storage medium, postoperative endophthalmitis may result from the transmission of bacteria via contaminated corneal tissue. The authors evaluated the antimicrobial activity and endothelial toxicity of vancomycin (10 micrograms/ml) in combination with gentamicin (100 micrograms/ml) in DexSol corneal storage medium. When tested against a panel of common ocular pathogens, vancomycin combined with gentamicin proved more effective than gentamicin alone for inhibiting the growth of Streptococcus pneumoniae at 4 degrees C after 1- and 5-day incubation periods. Ultrastructural and morphometric analyses of paired human corneas stored for 5 days in either DexSol supplemented with vancomycin combined with gentamicin or DexSol with gentamicin alone did not show a significant difference in endothelial toxicity between the two groups. These results suggest that vancomycin combined with gentamicin has superior antimicrobial effect and similar corneal toxicity when compared with media supplemented with gentamicin alone.