[Techniques for preparing postmortem human eyes to perform anterior segment intraocular surgery]. / Técnicas para la preparación de ojos de cadáver utilizadas para practicar cirugía intraocular del segmento anterior.

We describe different methods to prepare postmortem human or animal eyes used at the Center for Research in Ocular Therapeutics and Biodevices at the Storm Eye Institute, Medical University of South Carolina, Charleston, SC, USA. These techniques have been utilized for performing different surgical procedures (phacoemulsification, extracapsular cataract extraction, etc.), and for training of surgeons in-transition. Performing these techniques in the wet-laboratory contributed to improve surgical skills to perform the critical steps of the phacoemulsification surgery. Pathological evaluation of pseudophakic postmortem human eyes using the Miyake-Apple posterior view and histology was helpful to analyze postoperative complications of cataract surgery (anterior capsule opacification and posterior capsule opacification) secondary to postoperative proliferation of lens epithelial cells into the capsular bag. Modifications in the surgical techniques and/or lens design may be helpful to reduce these postoperative complications. Implantation of various aphakic and phakic intraocular lenses in postmortem human eyes as well as animal eyes was helpful to analyze the sizing and fitting of new lens designs within the eye.

[Diffuse lamellar keratitis: prophylactic treatment with ketorolac tromethamine 0.5% in an animal model]. / Queratitis lamelar difusa: tratamiento profiláctico con ketorolaco trometamina 0,5% en un modelo animal.

PURPOSE: The objective of this study is to evaluate the use of a topical non-steroidal anti-inflammatory drug in the treatment of induced diffuse lamellar keratitis (DLK) in an animal model. MATERIALS AND METHODS: A corneal flap was created in 40 eyes of 20 Dutch-belted rabbits using the ASC microkeratome. The interface was inoculated with either Pseudomonas Aeruginosa Lipopolysaccharide (LPS) endotoxin or Ultra Palmolive liquid dish washer. The rabbits were divided in two groups: Group I (n=20) treated with ketorolac tromethamine ophthalmic solution 0.5% 4 times a day and the group II (n=20) used as control. The rabbits were examined at the slit lamp at day 1, 3, 5 and 7 postoperatively. DLK was graded from I-IV. RESULTS: At the end of the study 31 eyes were available for evaluation. 28 eyes (90%) developed DLK: 86% of the treated group and 94% of the control group during the follow-up. The treated group showed a lower rate of DLK as well as a lower severity. However, no statistically significant difference was found when comparing both groups (P>0.05). CONCLUSION: Pseudomonas aeruginosa LPS endotoxin and Palmolive Ultra can induce DLK in rabbit eyes. The postoperative prophylactic treatment with a topical non-steroidal anti-inflammatory drug showed a tendency towards a lower DLK rate as well as the severity of the disease.

[Diffuse lamellar keratitis. Postoperative prophylactic treatment with corticosteroids in an experimental animal study]. / Diffuse lamelläre Keratitis Tierexperimentelle Studie zur Evaluierung einer postoperativen Kortikosteroidprophylaxe.

PURPOSE: The aim of this experimental ani-mal study was to induce diffuse lamellar keratitis (DLK), and investigate a prophylactic treatment with corticosteroids. MATERIALS AND METHODS: A corneal flap was cut in 40 eyes from 20 Dutch-belted rabbits and the interface inoculated with either Pseudomonas aeruginosa lipopolysaccharide (LPS) endotoxin ( n=21) or Palmolive Ultra soap ( n=19). Half of the eyes were treated with topical corticosteroids and the other half remained untreated. Slitlamp examinations were performed 1, 3, 5 and 7 days postoperatively and DLK was graded from I-IV. RESULTS: At the end of the study 33 eyes were available for evaluation and 94% of the non-treated eyes developed DLK. Out of those eyes treated with steroids 19% developed DLK during the 1 week follow-up period. This was statistically significantly lower ( P=0.018) when compared to the untreated group. CONCLUSION: Pseudomonas aeruginosa LPS endotoxin as well as Palmolive((R)) Ultra caused a very high rate of DLK in rabbit eyes. The postoperative prophylactic treatment with corticosteroids showed a statistically significant lower DLK rate in this rabbit eye model.

[Complication profiles of posterior chamber intraocular lenses IOL). An analysis of 586 foldable and 2077 rigid explanted intraocular lenses]. / Komplikationsprofile von Hinterkammerlinsen. Eine Analyse 586 faltbarer und 2.077 rigider (PMMA-)explantierter Intraokularlinsen.

BACKGROUND: Foldable intraocular lenses (IOL) have become increasingly preferred choice for IOL implantation after cataract removal. However, both foldable as well as rigid IOLs are not yet complication-free and may need explanation. MATERIAL AND METHODS: A total of 2663 explanted posterior chamber IOLs (PCIOLs) were accessioned at the Center for Research on Ocular Therapeutics and Biodevices between January 1988 and September 2000. The lenses were examined grossly using a Leitz/Wild M-8-Zoom stereomicroscope. The clinical reasons for explanation were documented for foldable as well as for rigid lenses. RESULTS: Of a total of 2663 explanted PCIOLs, 586 were foldable lenses and 2077 were rigid PMMA lenses The most frequent reason for explantation of all 2663 IOLs studied was decentration/dislocation. Optic and haptic damage and posterior capsule rupture were significantly more often a reason for explantation in several foldable designs compared to rigid PCIOLs. Whereas rigid designs lead more often to corneal decompensation. The percentage of explanted IOLs because of inflammatory reactions decreased significantly from 1994 to 2000. CONCLUSIONS: The complication profiles of rigid and foldable IOLs revealed some apparent differences due to the nature of the IOL biomaterials and designs. IOL optic/haptic damage was a common complication for foldable IOLs, whereas it was only discovered in single digits for rigid PMMA IOLs. The possible explanation for this is, that the soft and flexible biomaterials, from which all the foldable IOLs were manufactured, are easier to be damaged during folding, unfolding and insertion procedure. In our opinion this relative disadvantage of foldable IOLs is by far outweighed by the numerous advantages of the small incision cataract surgery. The decreasing inflammatory reactions can be explained by advances in surgical techniques, especially the secure in-the-bag fixation of IOLs.

[Morphological autopsy findings in human eyes implanted with Ridley intraocular lenses]. / Morphologische Befunde menschlicher Autopsieaugen nach Implantation von Ridley-Intraokularlinsen.

BACKGROUND: Sir Harold Ridley's first cataract extraction with implantation of an intraocular lens (IOL) marked the beginning of a major change in the practice of ophthalmology. MATERIAL AND METHODS: Two human autopsy globes implanted with original Ridley IOLs were grossly examined from behind with the Miyake-Apple photographic technique. The anterior segments were evaluated histologically. One Ridley IOL was examined by scanning electron microscopy. RESULTS: Both IOLs maintained a clear visual axis and had been placed in the capsular sac. The right lens was decentered inferiorly, the left IOL was well centered. The posterior capsule showed only minimal capsular opacification. Scanning electron microscopy (SEM) of the explanted IOL showed a smooth, well polished surface. CONCLUSIONS: In this patient Ridley IOLs maintained an ideal visual rehabilitation of 20/20 in both eyes, 22 and 18 years postoperatively. One surprising finding was the presence of a square, truncated optic edge geometry, very similar to that seen in some modern foldable IOLs. In our opinion the absence of posterior capsule opacification of the Ridley IOL may have partially been a result of this nearly sharp optic edge, that we confirmed by SEM. Even 22 years after implantation the Ridley IOL showed a high finish quality. Many of Sir Harold Ridley's early concepts like the IOL placement in the posterior chamber and endocapsular implantation are now the standard of modern cataract surgery.

[Millenniums update on posterior capsule opacification (PCO) scores, centration, biocompatibility and fixation of foldable intraocular lenses (IOL) - an analysis of 1,221 pseudophakic post mortem globes]. / Nachstarrate, Zentrierverhalten, Biokompatibilität und Fixation intraokularer Faltlinsen - eine Milleniums-Analyse 1221 pseudophaker Autopsieaugen.

BACKGROUND: The ongoing and fast evolution of foldable IOL designs established the necessity to evaluate the different abilities of each lens style. The large IOL database (over 16,500 specimens) acquired in our laboratory, has permitted us to perform a clinico-pathological analysis on pseudophakic autopsy globes provided from sources worldwide, especially many Lions Eye banks in the United States. MATERIAL AND METHODS: We analyzed 6 foldable IOL styles commonly implanted in the United States, using one type of rigid IOL design (1-piece design rigid PMMA optics) as a comparison group. Posterior capsule opacification (PCO) score, decentration, fixation, presence or absence of a Nd:YAG laser posterior capsulotomy and area and intensity of Soemmerring's ring formation was discerned by examination under an operating microscope using the Miyake-Apple posterior photographic technique. RESULTS: The four lenses with the lowest rates ranging between 3.8 % and 21.7 % are modern designs, mostly implanted after 1992. The two lenses with the higher rates ranging between 23.1 % and 30.4 %, were all older designs, already prevalent prior to 1992. IOL fixation with both haptics in the capsular bag showed the best centration values and PCO scores. Our studies to date have shown in a preliminary fashion that the AcrySoftrade mark IOL displays the the lowest (best) biocompatibility score. CONCLUSIONS: Entering the new millenium, with evolution of modern surgical techniques and IOL designs, the incidence of the two major complications of cataract surgery, decentration and PCO are now finally diminishing.

[Postoperative opacification of posterior chamber intraocular lenses - a review]. / Postoperative Trübung von Hinterkammerlinsen - eine Ubersicht.

Postoperative opacification of intraocular lenses (IOLs) is a very unpleasant complication for the ophthalmic surgeon and the patient. We report on our experiences with opacification of different foldable IOL designs and rigid poly (methyl methacrylate) (PMMA) posterior chamber lenses.1. Snowflake degeneration of PMMA IOLs: This condition is an unanticipated and surprising late postoperative finding 8 to 15 years after implantation. In our opinion, this complication is probably not related to the PMMA biomaterial itself, but rather it appears to represent a manufacturing problem that has affected a selected, albeit large number of lenses manufactured in the 1980s-mid 1990s.2. Degeneration of UV absorber material and calcium deposits within the optic of hydrophilic IOLs: Two years postoperatively degenerations of UV absorber material and calcium deposits within the optic of single piece hydrophilic acrylic lenses SC60B-OUV manufactured by MDR (Medical developmental research Inc. Clearwater FL, USA) can occur. Although the precise mechanism is not fully known, it was assumed that these opacifications are due to premature aging of the UV blocking agent incorporated in the lens biomaterial and calcification.3. Calcification on the surface of the Bausch & Lomb Hydroviewtrade mark IOLs: Twelve to 15 months postoperatively granular surface calcifications in Hydroviewtrade mark IOLs occured. The mechanism is not fully understood. According to Bausch and Lomb studies, part of the components of the packaging contained silicone, which may have come off the packaging onto the lens optic, where it then appears to be a catalyst for calcium precipitation. The manufacturer has correlated a change in packaging with the appearance of the opacification. The manufacturer now believes that this problem has been solved. However, final verification will require a careful 1 - 2 years clinical study.4. Glistenings in the hydrophobic acrylic AcrySoftrade mark IOLs: The time frame of glistenings in the AcrySoftrade mark IOLs is highly variable. It has been suggested that the occurrence of glistenings may be related to variations in the temperature of the lens just prior to and or during insertion into the eye. Formation of vacuoles may occur within the submersed acrylic polymer when there is a transient increase and then decrease in temperature during the surgical procedure. "Glistenings" may then subsequently form by ingress of anterior chamber fluid. Contrast sensitivity can been decreased in some patients, but clinically significant decrease of visual acuity has been rare.

[Influence of surgery-related factors on the Nd:YAG laser capsulotomy rates of 3-piece silicone IOLs - analysis of 457 pseudophakic human globes obtained post mortem]. / Einfluss chirurgischer Faktoren auf die Kapsulotomierate dreistückiger Silikon-Intraokularlinsen - Analyse 457 pseudophaker Autopsieaugen12.

BACKGROUND: The purpose of this study was to analyze any possible surgical reasons which may have had caused posterior capsule opacification in 3-piece silicone IOLs that had required Nd:YAG laser treatment. Special attention was given to 1) quality of cortical clean up, 2) type of haptic fixation, and 3) continuous curvilinear capsulorhexis (CCC) size and shape. MATERIALS AND METHODS: Human eyes obtained post-mortem implanted with 3-piece silicone optic - PMMA haptic (SI 40 NB) and 3-piece silicone optic - Prolene haptic (SI 30 NB) designs IOLs, accessioned between January 1993 and December 2000 were evaluated by gross examination from behind under an operating microscope using the Miyake-Apple posterior photographic technique. The area and intensity of Soemmerring's ring and type of fixation was studied in 457 eyes. The mean diameter of the CCC and relation of the CCC edge to the optic rim were analyzed in 221 eyes. RESULTS: 1) The amount of Soemmerring's ring formation was significantly larger in the group of IOLs requiring Nd:YAG capsulotomy in both the SI 40 NB and SI 30 NB design than in the IOLs without capsulotomies. 2) The percentage of not in-the-bag fixated IOLs in both the SI 40 NB and SI 30 NB design was larger in the "Nd:YAG groups", without being statistically significant. 3) The "Nd:YAG groups" showed a significant higher amount of non overlapping clock hours of the CCC edge in relation to the optic rim. CONCLUSION: 1) The data confirm the clinical assumption that the incidence of PCO is correlated with the cortical clean up. 2) Our findings also support the clinical assumption, that poor IOL fixation increases the risk of PCO. 3) This study also verifies the relation of the CCC to PCO, namely a relatively small CCC covering the entire optic rim is best to reduce the Nd:YAG laser rate.

Surgeon and type of anesthesia predict variability in surgical procedure times.

BACKGROUND: Variability in surgical procedure times increases the cost of healthcare delivery by increasing both the underutilization and overutilization of expensive surgical resources. To reduce variability in surgical procedure times, we must identify and study its sources. METHODS: Our data set consisted of all surgeries performed over a 7-yr period at a large teaching hospital, resulting in 46,322 surgical cases. To study factors associated with variability in surgical procedure times, data mining techniques were used to segment and focus the data so that the analyses would be both technically and intellectually feasible. The data were subdivided into 40 representative segments of manageable size and variability based on headers adopted from the common procedural terminology classification. Each data segment was then analyzed using a main-effects linear model to identify and quantify specific sources of variability in surgical procedure times. RESULTS: The single most important source of variability in surgical procedure times was surgeon effect. Type of anesthesia, age, gender, and American Society of Anesthesiologists risk class were additional sources of variability. Intrinsic case-specific variability, unexplained by any of the preceding factors, was found to be highest for shorter surgeries relative to longer procedures. Variability in procedure times among surgeons was a multiplicative function (proportionate to time) of surgical time and total procedure time, such that as procedure times increased, variability in surgeons' surgical time increased proportionately. CONCLUSIONS: Surgeon-specific variability should be considered when building scheduling heuristics for longer surgeries. Results concerning variability in surgical procedure times due to factors such as type of anesthesia, age, gender, and American Society of Anesthesiologists risk class may be extrapolated to scheduling in other institutions, although specifics on individual surgeons may not. This research identifies factors associated with variability in surgical procedure times, knowledge of which may ultimately be used to improve surgical scheduling and operating room utilization.

Modeling the uncertainty of surgical procedure times: comparison of log-normal and normal models.

BACKGROUND: Medical institutions are under increased economic pressure to schedule elective surgeries efficiently to contain the costs of surgical services. Surgical scheduling is complicated by variability inherent in the duration of surgical procedures. Modeling that variability, in turn, provides a mechanism to generate accurate time estimates. Accurate time estimates are important operationally to improve operating room utilization and strategically to identify surgeons, procedures, or patients whose duration of surgeries differ from what might be expected. METHODS: The authors retrospectively studied 40,076 surgical cases (1,580 Current Procedural Terminology-anesthesia combinations, each with a case frequency of five or more) from a large teaching hospital, and attempted to determine whether the distribution of surgical procedure times more closely fit a normal or a log-normal distribution. The authors tested goodness-of-fit to these data for both models using the Shapiro-Wilk test. Reasons, in practice, the Shapiro-Wilk test may reject the fit of a log-normal model when in fact it should be retained were also evaluated. RESULTS: The Shapiro-Wilk test indicates that the log-normal model is superior to the normal model for a large and diverse set of surgeries. Goodness-of-fit tests may falsely reject the log-normal model during certain conditions that include rounding errors in procedure times, large sample sizes, untrimmed outliers, and heterogeneous mixed populations of surgical procedure times. CONCLUSIONS: The authors recommend use of the log-normal model for predicting surgical procedure times for Current Procedural Terminology-anesthesia combinations. The results help to legitimize the use of log transforms to normalize surgical procedure times before hypothesis testing using linear statistical models or other parametric statistical tests to investigate factors affecting the duration of surgeries.

Surgical subspecialty block utilization and capacity planning: a minimal cost analysis model.

BACKGROUND: Operational inefficiencies in the use of operating rooms (ORs) are hidden by traditional measures of OR utilization. To better detect these inefficiencies, the authors defined two new terms, underutilization and overutilization, and illustrated how these measures might be used to evaluate the use of surgical subspecialty ORs. The authors also described capacity planning (optimizing surgical subspecialty block time allotments) using a minimal cost analysis (MCA) model. METHODS: The authors evaluated post hoc all surgeries performed over 6 yr at a large teaching hospital. To prepare utilization estimates, surgical records were categorized relative to budgeted OR block time for each subspecialty. Surgical cases beginning and ending during budgeted OR block time were categorized as budgeted utilization, budgeted time not used for surgery was underutilization, and cases beginning before/after budgeted block time were classified as overutilization. Cases that overlapped budgeted and nonbudgeted OR block time were parsed and the portions were assigned appropriately. Probability distributions were fitted to the historical patterns of surgical demand, and MCA block time budgets were estimated that minimized the costs of underutilization and overutilization for each subspecialty. To illustrate the potential savings if these MCA budgets were implemented, the authors compared actual operational costs to the estimated MCA budget costs and expressed the savings as a percentage of actual costs. RESULTS: The authors analyzed data from 58,251 surgical cases and 10 surgical subspecialty blocks. Classic utilization for each block-day by surgical subspecialty ranged from 44-113%. Average daily block-specific underutilization ranged from 16 to 60%, whereas overutilization ranged from 4 to 49%. CONCLUSIONS: Underutilization and overutilization are important measures because they may be used to evaluate the quality of OR schedules and the efficiency of OR utilization. Overutilization and underutilization also allow capacity planning using an MCA model This study indicated that the potential savings, if the MCA budgets were to be implemented, would be significant.

Design of RCSS: Resource Coordination Systems for Surgical Services using distributed communications.

The plans for Resource Coordination for Surgical Services system (RCSS) incorporate a distributed objectbase with a coordinating server. User-centered information screens are customized for each geographic location in surgical services. User interfaces are designed to mimic paper lists and worksheets used by health care providers. Patient-specific and site-specific data will be entered and maintained by providers at each geographic location, but also rebroadcast and displayed for all providers. Although RCSS is primarily a communications system, it will also support review of surgical utilization and operative scheduling.

Surgical suite utilization and capacity planning: a minimal cost analysis model.

In this paper, we are concerned with cost reduction, operating suite utilization, and capacity planning in surgical services. We studied 58,251 computerized surgical records from a teaching hospital to determine a model for measuring operating suite utilization, analyzing the quality of surgical schedules, and allocating surgical suite budgets (capacity planning). The classical definition of operating suite (OR) utilization, encountered in the literature is the ratio of the total OR time used to the total OR time allocated or budgeted. To create a better measure of utilization, we measured underutilization and overutilization providing a more complete description of the overall use of resources. Because the costs of under and overutilization of operating suites are high, they are attractive potential targets for cost minimization and the magnitude of the potential savings are such that attempts to measure and eliminate this inefficiency could be financially rewarding.