David Davis-Boozer

Graft Dislocation and Hypotony after Descemet's Stripping Automated Endothelial Keratoplasty in Patients with Previous Glaucoma Surgery

PURPOSE To determine if patients with prior glaucoma surgery experience higher rates of postoperative graft dislocation after Descemets stripping automated endothelial keratoplasty (DSAEK) and to determine if postoperative hypotony may be a risk factor in these patients. DESIGN Retrospective, comparative analysis of an interventional case series. PARTICIPANTS Eight hundred fifty-four eyes (67 eyes with prior glaucoma surgery and 787 controls) from 582 patients who underwent DSAEK at 1 institution between January 2005 and April 2011. METHODS Groups were compared with regard to preoperative, intraoperative, and postoperative parameters. Continuous variables were compared using the independent samples t test or Mann-Whitney U test. Categorical variables were compared using the chi-square test or Fisher exact test. MAIN OUTCOME MEASURES Frequencies of postoperative graft dislocation and postoperative hypotony. RESULTS Study eyes before surgery differed from control eyes with regard to corneal thickness (768 vs. 655 μm; P<0.001) and intraocular pressure (13 vs. 16 mmHg; P<0.001). Postoperative graft dislocation occurred significantly more frequently in study eyes compared with control eyes (9% vs. 2%; P = 0.008). Among eyes in which dislocation occurred, postoperative hypotony was present in 5 study eyes (83%) and 0 control eyes. CONCLUSIONS Previous glaucoma surgery was associated with a significantly increased rate of graft dislocation compared with control eyes. Dislocation was related strongly to postoperative hypotony in eyes with prior glaucoma surgery. FINANCIAL DISCLOSURE(S) Proprietary or commercial disclosure may be found after the references.

Ultrathin DSAEK Tissue Prepared With a Low-Pulse Energy, High-Frequency Femtosecond Laser

Purpose: To evaluate the endothelial cell survival and stromal bed quality when creating deep stromal cuts with a low–pulse energy, high-frequency femtosecond laser to produce “ultrathin” tissue for Descemet stripping automated endothelial keratoplasty. Methods: Seventeen corneas were used for this study. Five corneas were cut with the laser at a depth of 420 to 500 &mgr;m to produce a tissue thickness of approximately ⩽70 &mgr;m. Five corneas served as an uncut comparison group. Vital dye staining and computer digitized planimetry analysis were performed on these corneas. The 7 remaining corneas were cut for scanning electron microscopy evaluation. Results: The mean central posterior stromal thickness of cut corneas was 60.6 &mgr;m (range, 43–72 &mgr;m). Endothelial cell damage in cut and comparison corneas was 3.92% ± 2.22% (range, 1.71%–6.51%) and 4.15% ± 2.64% (range, 1.21%–7.01%), respectively (P = 0.887). Low-magnification (×12) scanning electron microscopy revealed a somewhat irregular-appearing surface with concentric rings peripherally. Qualitative grading of higher magnification (×50) central images resulted in an average score of 2.56 (between smooth and rough). Conclusions: Ultrathin tissue for Descemet stripping automated endothelial keratoplasty can be safely prepared with minimal endothelial cell damage using a low–pulse energy, high-frequency femtosecond laser; however, the resulting stromal surface quality may not be optimal with this technique.

The endothelial safety of using a gentian violet dry-ink "S" stamp for precut corneal tissue.

Purpose: To determine the endothelium damage resulting from the application of “dry” gentian violet (GV) stromal markings on corneas precut for Descemet stripping automated endothelial keratoplasty (DSAEK) using a Moria “S” Stamp. Methods: Five precut corneas had the stromal graft bed marked with GV using the Moria “S” stamp and 6 precut corneas were left unmarked as controls. After applying the ink to the stamp, care was taken to allow the alcohol carrier to dry for 10 seconds before applying the dry dye to the stromal surface. Tissue was then trephinated and stained with calcein AM to assess endothelial viability. Grafts were photographed and digital pixel planometry, using an established analysis technique, was used to compare the damage between the control and experimental groups. Results: The mean percent cell damage of corneas treated with GV “S” stamp (n = 5) was 8.6% (range 4.4–12.9), and it was 8.1% (range 3.9–15.1) in the DSAEK control set (n = 6). Median percent cell damage was 6.7% among GV-treated corneas and 7.4% among control corneas. The distributions were not significantly different between groups (Mann–Whitney U test = 15.0, two-tailed P = 1.0). Moreover, no “S” pattern of damage was seen in any study eye. Conclusions: There were no significant differences in endothelial damage between the 2 groups. GV stromal markings may be applied without undue damage to the endothelium using the dry-ink technique described.

A novel dominant mutation in SAG, the arrestin-1 gene, is a common cause of retinitis pigmentosa in hispanic families in the Southwestern United States

Purpose To identify the causes of autosomal dominant retinitis pigmentosa (adRP) in a cohort of families without mutations in known adRP genes and consequently to characterize a novel dominant-acting missense mutation in SAG. Methods Patients underwent ophthalmologic testing and were screened for mutations using targeted-capture and whole-exome next-generation sequencing. Confirmation and additional screening were done by Sanger sequencing. Haplotypes segregating with the mutation were determined using short tandem repeat and single nucleotide variant polymorphisms. Genealogies were established by interviews of family members. Results Eight families in a cohort of 300 adRP families, and four additional families, were found to have a novel heterozygous mutation in the SAG gene, c.440G>T; p.Cys147Phe. Patients exhibited symptoms of retinitis pigmentosa and none showed symptoms characteristic of Oguchi disease. All families are of Hispanic descent and most were ascertained in Texas or California. A single haplotype including the SAG mutation was identified in all families. The mutation dramatically alters a conserved amino acid, is extremely rare in global databases, and was not found in 4000+ exomes from Hispanic controls. Molecular modeling based on the crystal structure of bovine arrestin-1 predicts protein misfolding/instability. Conclusions This is the first dominant-acting mutation identified in SAG, a founder mutation possibly originating in Mexico several centuries ago. The phenotype is clearly adRP and is distinct from the previously reported phenotypes of recessive null mutations, that is, Oguchi disease and recessive RP. The mutation accounts for 3% of the 300 families in the adRP Cohort and 36% of Hispanic families in this cohort.

The safety and efficacy of linezolid and daptomycin as an additive in Optisol-GS against methicillin-resistant Staphylococcus aureus.

Purpose: To evaluate the efficacy of adding either linezolid or daptomycin to Optisol-GS donor storage medium in reducing methicillin-resistant Staphylococcus aureus (MRSA) contamination of donor corneas. Methods: Optisol-GS was supplemented with either linezolid at 2×, 4×, or 10× minimum inhibitory concentration (MIC) or daptomycin and calcium at 5× or 50× MIC. Unsupplemented control groups were also used. Gentamicin-sensitive and gentamicin-resistant isolates of MRSA were added, and vials were refrigerated for 48 hours followed by sampling for viable colony counts immediately upon removal from refrigeration and after warming to room temperature for 3 hours. Safety studies of Optisol-GS supplemented with 50× MIC daptomycin and calcium were performed by evaluating the central corneal thickness and endothelial cell density of the donor cornea. Stability of daptomycin in Optisol-GS at storage was also tested. Results: No added benefit was observed with linezolid supplementation to Optisol-GS against gentamicin-sensitive MRSA, with reduction in viable colony counts by >90% in all groups. No benefit was observed with linezolid supplementation against gentamicin-resistant MRSA, with the majority of inocula remaining viable in all groups. Viable counts of gentamicin-sensitive MRSA and gentamicin-resistant MRSA were effectively reduced with both 5× MIC and 50× MIC daptomycin supplementation. 50× MIC daptomycin–supplemented Optisol-GS had no appreciable effect on the central corneal thickness or endothelial cell density of the donor cornea and was stable at storage for 14 days. Conclusions: The addition of daptomycin to Optisol-GS significantly increases the anti-MRSA activity of the medium without any apparent negative effects on donor corneal tissue.