Using a Novel Microfabricated Model of the Alveolar-Capillary Barrier to Investigate the Effect of Matrix Structure on Atelectrauma.

The alveolar-capillary barrier is composed of epithelial and endothelial cells interacting across a fibrous extracelluar matrix (ECM). Although remodeling of the ECM occurs during several lung disorders, it is not known how fiber structure and mechanics influences cell injury during cyclic airway reopening as occurs during mechanical ventilation (atelectrauma). We have developed a novel in vitro platform that mimics the micro/nano-scale architecture of the alveolar microenvironment and have used this system to investigate how ECM microstructural properties influence epithelial cell injury during airway reopening. In addition to epithelial-endothelial interactions, our platform accounts for the fibrous topography of the basal membrane and allows for easy modulation of fiber size/diameter, density and stiffness. Results indicate that fiber stiffness and topography significantly influence epithelial/endothelial barrier function where increased fiber stiffness/density resulted in altered cytoskeletal structure, increased tight junction (TJ) formation and reduced barrier permeability. However, cells on rigid/dense fibers were also more susceptible to injury during airway reopening. These results indicate that changes in the mechanics and architecture of the lung microenvironment can significantly alter cell function and injury and demonstrate the importance of implementing in vitro models that more closely resemble the natural conditions of the lung microenvironment.

Pseudophakia and polypseudophakia in the first year of life.

PURPOSE: To report a consecutive series of patients undergoing intraocular lens (IOL) implantation in the first year of life. A new procedure, referred to as temporary polypseudophakia, is reported. METHODS: A retrospective chart analysis was conducted. Ocular growth and refractive change, complications and reoperation rates, and outcomes were analyzed. RESULTS: Forty-seven eyes of 33 patients underwent IOL implantation in the first year of life. Average follow-up was 22 months (range, 7 weeks to 5 years). Thirty-two eyes of 22 patients had a single IOL implanted from 12 days to 11 months of age. Fifteen eyes of 11 infants received piggyback IOLs from 16 days to 6.8 months of age. Reoperation for complications within the anterior segment of the eye was needed in 23% of all patients (22% for single IOLs, 26% for piggyback IOLs). The average first postoperative refraction after single IOL was +7.98 D and after piggyback IOL was +1.67 D. The average last postoperative refraction was +1.76 D and -4.48 D, respectively. On average, eyes grew 2.68 mm over 17.5 months of follow-up. Eight patients were old enough for Snellen visual acuity, but each had deprivation amblyopia with visual acuities from 20/85 to 5/200. Of the remaining 25 patients, 17 had central, steady, and maintained fixation in the implanted eyes. CONCLUSION: IOL implantation in infancy is technically feasible and associated with a reoperation rate of approximately 25% in the first 2 years after implantation. Further follow-up is required before meaningful visual acuity data and long-term results can be reported.

The effect of anemia on retinopathy of prematurity in extremely low birth weight infants.

OBJECTIVE: Numerous risk factors for development of retinopathy of prematurity (ROP) in very low birth weight infants have been identified in the literature. However, the role of anemia in the development of ROP has not been adequately addressed. STUDY DESIGN: We retrospectively examined the medical records of all infants weighing < or = 800 g who were admitted to a university hospital between July 1, 1992 and December 30, 1997. Highest and lowest hemoglobin and hematocrit values and the number of blood transfusions were recorded at each week of life during hospitalization. Gestational age at birth, birth weight, race, sex, oxygen status, history of bronchopulmonary dysplasia, length of hospital stay, and sepsis were also identified as potential risk factors. Data were analyzed using logistic regression to adjust for these confounding variables. RESULTS: Infants were grouped according to ROP status in the following manner: stage 0 to 1 ROP, stage 2 ROP, and stage 3 to threshold ROP. Sex, gestational age at birth, bronchopulmonary dysplasia, ventilator days, length of hospital stay, and number of blood transfusions were significantly associated with severity of ROP by univariate analysis. Using a logistic regression model, only gestational age (p = 0.007) and number of blood transfusions (p = 0.04) remained statistically significant. CONCLUSIONS: Anemia did not affect severity of ROP as an independent risk factor. However, the number of blood transfusions did affect the highest stage of ROP in this group of premature infants. Infants who remained severely anemic (Hgb < or = 8 g/dl or Hct < or = 25%) for longer periods of time developed milder ROP than less anemic infants.

Postoperative intraocular pressure elevation after the use of Healon GV in pediatric cataract surgery.

Intraocular pressure elevation after the use of viscoelastic agents in uncomplicated cataract surgery has been well documented in adults. However, pediatric patients are thought to clear residual viscoelastic agents from the anterior chamber more easily than adults, presumably because of healthier trabecular meshwork. (1) We report on a series of 4 eyes of 4 children with previously normal intraocular pressure who underwent cataract extraction with primary (3 patients) or secondary (1 patient) intraocular lens implantation with Healon GV, which was complicated by marked postoperative intraocular pressure elevation (greater than 30 mm Hg). The patients, aged 5 to 14 years, had an intraocular pressure ranging from 34 to 50 mm Hg with Tonopen or applanation tonometry 1 day, postoperatively associated with nausea, eye pain, and microcystic corneal edema. Viscoelastic material was not entirely removed during surgery. Each of these cases occurred after a change in our preferred viscoelastic agent from one with less viscosity to Healon GV. Medical management controlled the elevated intraocular pressure in all cases without affecting the visual outcome. However, 1 patient with intractable nausea and vomiting required hospitalization for rehydration. With meticulous removal of all viscoelastic material at the completion of surgery, we have not documented any additional cases of postoperative pressure elevation.

In-the-bag secondary intraocular lens implantation in children.

BACKGROUND: Surgery for congenital cataracts in early infancy usually includes a primary posterior capsulectomy and an anterior vitrectomy. Initially, most of these infants have aphakia after surgery. Over time, remaining equatorial lens epithelial cells produce new cortical fibers, resulting in a ring of cortex trapped between the lens equator and the fused anterior and posterior capsulectomy edges. A potential space is maintained between the anterior and posterior capsular leaflets. We describe a technique for placing a secondary intraocular lens (IOL) within the capsular bag. PATIENTS AND METHODS: Eight children, ranging in age from 11 months to 14 years, who originally had aphakia after cataract extraction were operated on with the intent to reopen the capsular bag and place an IOL in the bag. RESULTS: Secondary in-the-bag IOL implantation was successfully completed in 7 of 8 children. This was accomplished by reopening the capsular bag 360 degrees at the edge of the fused anterior and posterior capsulectomy remnants, using the previously published vitrectorhexis technique. Residual cortical material was aspirated, and an IOL was placed within the capsular bag. In 1 child, aged 14 years, the capsular bag was reopened, but the lens was placed in the ciliary sulcus because the new anterior capsule edge could not be visualized for 360 degrees . CONCLUSION: Placement of secondary IOLs within the capsular bag can be accomplished successfully for selected patients in the pediatric population. Surgeons operating on infantile cataracts without primary IOL placement can facilitate capsular IOL sequestration later by limiting the anterior and posterior capsulectomy to 4 to 5 mm and performing a generous anterior vitrectomy to help prevent secondary closure of the smaller capsulectomy.

The Ahmed valve in refractory pediatric glaucoma.

PURPOSE: To evaluate the efficacy of the Ahmed Glaucoma Valve implant in pediatric patients with refractory glaucoma. METHODS: A retrospective chart review was conducted of 27 eyes from 23 consecutive pediatric patients (younger than 18 years) with refractory glaucoma treated with Ahmed Glaucoma Valve implant placement. The main outcome measure was time after surgery without failure. Success was defined as an intraocular pressure of 21 mm Hg or less without visually devastating complications or additional glaucoma surgery (exclusive of tube revision). Previous cycloablation, which was present in a subset of eyes, was examined as a possible influence on postoperative intraocular pressure control, glaucoma medication dependence, and surgical success. RESULTS: The median patient age was 4.8 years (range, 0.3 to 16.8 years), with a follow-up of 3 to 31 months (mean, 12.6 +/- 8.2 months). Intraocular pressure was reduced from a preoperative mean of 32.8 +/- 7.5 mm Hg to 16.7 +/- 5.4 mm Hg at 18 months postoperatively, with an overall success rate of 85.2% at last follow-up. Cumulative probabilities of success by Kaplan-Meier analysis were 90.6% at 12 months and 58.3% at 24 months. Compared with those that did not undergo previous cycloablation, eyes that had undergone previous cycloablation had a lower mean postoperative intraocular pressure at 3- and 6-month follow-up (P < .001 and P = .057, respectively) and required fewer glaucoma medications at postoperative examination time points up to 18 months (P < or = .01 at each time point). Fifteen eyes (56%) required glaucoma medications after surgery. The most common complication was corneal-tube contact, which occurred in five eyes (18.5%). One eye with a wound leak required anterior chamber reformation. Retinal detachment occurred in one aphakic eye 2 years postoperatively, resulting in loss of vision. One eye with neovascular glaucoma required enucleation after an enlarging (presumably preexisting) medulloepithelioma was discovered. CONCLUSIONS: Ahmed Glaucoma Valve implantation is a useful therapy for the treatment of refractory pediatric glaucoma, and it may be safely used in a subgroup of eyes with uncontrolled intraocular pressure despite previous cycloablation procedures.

Argon vs diode laser trabeculoplasty.

PURPOSE: To compare the efficacy of diode laser and argon laser trabeculoplasty in a randomized prospective study of 11 paired fellow eyes. METHODS: Fellow eyes of 11 patients, having had no prior laser trabeculoplasty and requiring laser trabeculoplasty to lower intraocular pressure, were randomly assigned prospectively to diode laser trabeculoplasty in one eye and argon laser trabeculoplasty in the other eye. RESULTS: In the diode laser group, the average baseline intraocular pressure was 21.6 +/- 2.0 mm Hg before trabeculoplasty and 19.6 +/- 2.1 mm Hg (or a 7.7% +/- 11.5% mean pressure reduction) at 1 month, 19.3 +/- 2.6 mm Hg (or a 6.9% +/- 13.5% mean reduction) at 2 months, and 19.0 +/- 3.3 mm Hg (or a 2.4% +/- 16.9% mean reduction) at 3 months postoperatively. In the argon laser group, the average intraocular pressure was 24.4 +/- 3.5 mm Hg before treatment and 17.6 +/- 1.7 mm Hg (or a 24.7% +/- 11.4% mean pressure reduction) at 1 month, 16.8 +/- 2.5 mm Hg (or a 26.7% +/- 15.3% mean reduction) at 2 months, and 15.5 +/- 1.2 mm Hg (or a 30.0% +/- 16.5% mean reduction) at 3 months after laser trabeculoplasty. The difference between argon and diode laser intraocular pressure reduction was statistically significant at 1 month (P < .01), 2 months (P < .01), and 3 months (P < .05) after treatment. CONCLUSION: Argon laser trabeculoplasty appears to be more effective than diode laser therapy in lowering intraocular pressure during the first 3 months after treatment.