Emily C. Greenlee

Impact of a structured surgical curriculum on ophthalmic resident cataract surgery complication rates

PURPOSE: To determine whether institution of a structured surgical curriculum for ophthalmology residents decreased the rate of sentinel surgical complications. SETTING: Veterans Affairs Medical Center, Des Moines, Iowa, USA. METHODS: A retrospective review was performed of third‐year ophthalmic resident quality‐assurance surgical outcomes data at a single residency‐training site from 1998 to 2008. The primary outcome measure was defined as a sentinel event; that is, a posterior capsule tear (with or without vitreous loss) or vitreous loss (from any cause) occurring during a resident‐performed case. The study population was divided into 2 groups. Group 1 comprised surgical cases of residents trained before the surgical curriculum change (academic years 1998 to 2003) and Group 2, surgical cases of residents trained with the enhanced curriculum (academic years 2004 to 2008). Data from 1 year (academic year 2003 to 2004) were excluded because the transition to the enhanced curriculum occurred during that period. The data were analyzed and adjusted for surgical experience. RESULTS: In Group 1 (before institution of surgical curriculum), there were 823 cases with 59 sentinel complications. In Group 2 (after institution of surgical curriculum), there were 1009 cases with 38 sentinel complications. There was a statistically significant reduction in the sentinel complication rate, from 7.17% before the curriculum changes to 3.77% with the enhanced curriculum (P = .001, unpaired 2‐tailed t test). CONCLUSION: Implementation of a structured surgical curriculum resulted in a statistically significant reduction in sentinel event complications, even after adjusting for surgical experience.

Automated Segmentation of the Cup and Rim from Spectral Domain OCT of the Optic Nerve Head

PURPOSE To evaluate the performance of an automated algorithm for determination of the cup and rim from close-to-isotropic spectral domain (SD) OCT images of the optic nerve head (ONH) and compare to the cup and rim as determined by glaucoma experts from stereo color photographs of the same eye. METHODS Thirty-four consecutive patients with glaucoma were included in the study, and the ONH in the left eye was imaged with SD-OCT and stereo color photography on the same day. The cup and rim were segmented in all ONH OCT volumes by a novel voxel column classification algorithm, and linear cup-to-disc (c/d) ratio was determined. Three fellowship-trained glaucoma specialists performed planimetry on the stereo color photographs, and c/d was also determined. The primary outcome measure was the correlation between algorithm-determined c/d and planimetry-derived c/d. RESULTS The correlation of algorithm c/d to experts 1, 2, and 3 was 0.90, 0.87, and 0.93, respectively. The c/d correlation of expert 1 to 2, 1 to 3, and 2 to 3, were 0.89, 0.93, and 0.88, respectively. CONCLUSIONS In this preliminary study, we have developed a novel algorithm to determine the cup and rim in close-to-isotropic SD-OCT images of the ONH and have shown that its performance for determination of the cup and rim from SD-OCT images is similar to that of planimetry by glaucoma experts. Validation on a larger glaucoma sample as well as normal controls is warranted.

Construct validity of a surgical simulator as a valid model for capsulorhexis training

PURPOSE: To compare the performance on the EYESi surgical simulator capsulorhexis training module between medical students and residents and experienced cataract surgeons. SETTING: Department of Ophthalmology, University of Iowa, Iowa City, Iowa, USA. DESIGN: Comparative case series. METHODS: The study comprised medical students and residents at the University of Iowa and experienced cataract surgeons. Neither group had experience with the simulator. Each participant completed 4 trials on the capsulorhexis module. RESULTS: The 7 experienced surgeons achieved statistically significantly better total scores than the 16 medical students and residents on the easy level and the medium level of the capsulorhexis module (P = .004 and P = .000007, respectively). Experienced surgeons achieved significantly better scores in all parameters at the medium level, with better centering (P = .001), less corneal injury (P = .02), fewer spikes (P = .03), less time operating without a red reflex (P = .0005), better roundness of the capsulorhexis (P = .003), and less time completing tasks (P = .008). CONCLUSION: The surgical simulator capsulorhexis module showed significant construct validity (P<.05). Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Graft failure: III. Glaucoma escalation after penetrating keratoplasty

Glaucoma after penetrating keratoplasty is a frequently observed post-operative complication and is a risk factor for graft failure. Penetrating keratoplasty performed for aphakic and pseudophakic bullous keratopathy and inflammatory conditions are more likely to cause postoperative glaucoma compared with keratoconus and Fuchs’ endothelial dystrophy. The intraocular pressure elevation may occur immediately after surgery or in the early to late postoperative period. Early postoperative causes of glaucoma include pre-existing glaucoma, retained viscoelastic, hyphema, inflammation, pupillary block, aqueous misdirection, or suprachoroidal hemorrhage. Late causes include pre-existing glaucoma, angle-closure glaucoma, ghost cell glaucoma, suprachoroidal hemorrhage, and steroid-induced glaucoma. Determining the cause of IOP elevation can help guide therapeutic intervention. Treatments for refractory glaucoma include topical anti-glaucoma medications such as beta-adrenergic blockers. Topical carbonic anhydrase inhibitors, miotic agents, adrenergic agonists, and prostaglandin analogs should be used with caution in the post-keratoplasty patient, because of the possibility of corneal decompensation, cystoid macular edema, or persistent inflammation. Various glaucoma surgical treatments have reported success in post-keratoplasty glaucoma. Trabeculectomy with mitomycin C can be successful in controlling IOP without the corneal toxicity noted with 5-fluorouracil. Glaucoma drainage devices have successfully controlled intraocular pressure in post-keratoplasty glaucoma; this is, however, associated with increased risk of graft failure. Placement of the tube through the pars plana may improve graft success compared with implantation within the anterior chamber. In addition, cyclophotocoagulation remains a useful procedure for eyes that have refractory glaucoma despite multiple surgical interventions.

Diurnal fluctuation and concordance of intraocular pressure in glaucoma suspects and normal tension glaucoma patients.

Purpose The study objective was to determine the concordance of intraocular pressure (IOP) in glaucoma suspects (GS) and normal tension glaucoma (NTG) patients. Methods This was a retrospective review of diurnal curves of untreated GS and NTG patients. No subject had IOP greater than 21 mm Hg. We defined GS patients as having suspicious optic nerves with normal visual fields, and NTG patients as having glaucomatous optic nerves with associated visual field loss. Goldmann applanation tonometry was performed at 10:00, 13:00, 16:00, 19:00, 22:00, and 07:00. Linear association of OD and OS IOP was estimated using Pearson correlation coefficient (r). The diurnal period was divided into 7 time intervals of 3, 6, 9, 12, 15, 18, and 21 hours, and the absolute difference in change in IOP between fellow eyes and probability that it was within 3 mm Hg were calculated. Results The study included 68 GS and 95 NTG subjects. The diurnal curves of the OD and OS showed a parallel course in both groups. The average correlations (r) of OD and OS IOP over the 6 time points were 0.78 and 0.81 for GS and NTG, respectively. The mean absolute difference in IOP change between OD and OS over the 6 time intervals ranged between 1.4 and 1.9 mm Hg for GS, and 1.3 and 1.5 mm Hg for NTG subjects. The probability that this difference was within 3 mm Hg ranged between 87% and 94% for GS, and 86% and 93% for NTG subjects. Conclusions The diurnal variation in IOP between the 2 eyes in GS and NTG is largely concordant in approximately 90% of the time.

Variance Owing to Observer, Repeat Imaging, and Fundus Camera Type on Cup-to-disc Ratio Estimates by Stereo Planimetry

ObjectiveTo determine and compare variance components in linear cup-to-disc ratio (LCDR) estimates by computer-assisted planimetry by human experts, and automated machine algorithm (digital automated planimetry). DesignProspective case series for evaluation of planimetry. ParticipantsForty-four eyes of 44 consecutive patients from the outpatient Glaucoma Service at University of Iowa with diagnosis of glaucoma or glaucoma suspect were studied. MethodsSix stereo pairs of optic nerve photographs were taken per eye: 3 repeat stereo pairs using simultaneous fixed-stereo base fundus camera (Nidek 3Dx) and another 3 repeat stereo pairs using sequential variable-stereo base fundus camera (Zeiss). Each optic disc stereo pair was digitized and segmented into cup and rim by 3 glaucoma specialists (computer-assisted planimetry) and using a computer algorithm (digital automated planimetry), and LCDR was calculated for each segmentation (either specialist or algorithm). A linear mixed model was used to estimate mean, SD, and variance components of measurements. Main Outcome MeasuresAverage LCDR, interobserver, interrepeat, intercamera coefficients of variation (CV) of LCDR and their 95% tolerance limits. ResultsThere was a significant difference in LCDR estimates among the 3 glaucoma specialists. The interobserver CV of 10.65% was larger than interrepeat (6.7%) or intercamera CV (7.6%). For the algorithm, the LCDR estimate was significantly higher for simultaneous stereo fundus images (Nidek, mean: 0.66) than for sequential stereo fundus images (Zeiss, mean: 0.64), whereas interrepeat CV for Nidek (4.4%) was lower than Zeiss (6.36%); the algorithms interrepeat and intercamera CV were 5.47% and 7.26%, respectively. ConclusionsInterobserver variability was the largest source of variation for glaucoma specialists, whereas their interrepeat and intercamera variability is comparable with that of the algorithm. DAP reduces variability on LCDR estimates from simultaneous stereo images, such as the Nidek 3Dx.

Graft survival versus glaucoma treatment after penetrating or Descemet stripping automated endothelial keratoplasty.

Purpose: The aim of this study was to assess and compare the association of glaucoma therapy with graft survival after performing penetrating keratoplasty (PKP) and Descemet stripping automated endothelial keratoplasty (DSAEK). Methods: A retrospective chart review was performed of cases: primary PKP from January 1, 2003, to December 31, 2005, or primary DSAEK from January 1, 2006, to December 31, 2008. Eyes with a surgical indication of pseudophakic corneal edema were included in the statistical analysis. Eyes were stratified by glaucoma treatment into those with (1) no glaucoma treatment, (2) medical therapy only, or (3) surgical intervention. The main outcome measure was graft survival. Results: Fifty-seven PKP-operated and 156 DSAEK-operated eyes met the inclusion criteria. After PKP and DSAEK, respectively, the 5-year Kaplan–Meier graft survival was 94.7% and 93.8% in eyes with no glaucoma treatment (P > 0.99), 93.8% and 96.3% in eyes with medical therapy only (P > 0.99), and 56.8% and 50% in eyes with surgical intervention (P > 0.99). After both procedures were performed, graft survival was significantly worse in eyes with surgical intervention compared with that in eyes with no glaucoma treatment (P < 0.0001) or in eyes with medical therapy alone (P < 0.0001). Conclusions: PKP and DSAEK have comparable graft survival in eyes without glaucoma management and in those with comparable glaucoma management.

Escalation of glaucoma therapy after deep lamellar endothelial keratoplasty

Purpose: To determine the prevalence and risk factors for escalation of glaucoma therapy after deep lamellar endothelial keratoplasty (DLEK). Methods: Retrospective review of every case of DLEK performed at a tertiary care facility between December 1, 2003 and January 31, 2006. Results: Eighty eyes met the inclusion criteria. Escalation of glaucoma therapy occurred in 13 eyes (16.3%) during a mean follow-up period of 27.1 months. Ten eyes required additional topical medical therapy, and 3 eyes required surgical intervention. Glaucoma therapy escalation was significantly associated with preexisting glaucoma (42.9% vs. 10.6%; P = 0.008). Conclusion: Escalation of glaucoma therapy is not uncommon after DLEK, especially in eyes with preexisting glaucoma.

3D reconstruction of the optic nerve head using stereo fundus images for computer-aided diagnosis of glaucoma

The shape of the optic nerve head (ONH) is reconstructed automatically using stereo fundus color images by a robust stereo matching algorithm, which is needed for a quantitative estimate of the amount of nerve fiber loss for patients with glaucoma. Compared to natural scene stereo, fundus images are noisy because of the limits on illumination conditions and imperfections of the optics of the eye, posing challenges to conventional stereo matching approaches. In this paper, multi scale pixel feature vectors which are robust to noise are formulated using a combination of both pixel intensity and gradient features in scale space. Feature vectors associated with potential correspondences are compared with a disparity based matching score. The deep structures of the optic disc are reconstructed with a stack of disparity estimates in scale space. Optical coherence tomography (OCT) data was collected at the same time, and depth information from 3D segmentation was registered with the stereo fundus images to provide the ground truth for performance evaluation. In experiments, the proposed algorithm produces estimates for the shape of the ONH that are close to the OCT based shape, and it shows great potential to help computer-aided diagnosis of glaucoma and other related retinal diseases.

Ethnic differences in the systemic pharmacology for ophthalmologists

Ophthalmology utilizes many topical and systemic medications in its practice. Although the ethnic differences among ophthalmic medications are not extensive, there are reported differences among the various medications. Mydriatic agents, immunosuppressive agents, and glaucoma medications are all utilized in the practice of ophthalmology and have shown documented ethnic differences. Although these differences are unlikely to alter the utilization of these medications, it is helpful to remember the differences in efficacy or side effects based on ethnicity.