Biomedical subjects

T A Macky

Publications and source records attributed to T A Macky.

10 recordsLinked to original sources

PubMed2001

Anterior capsule opacification: correlation of pathologic findings with clinical sequelae.

OBJECTIVE: To evaluate the degree of anterior capsule opacification (ACO) in human eyes obtained postmortem containing various rigid and foldable posterior chamber intraocular lens (PC-IOL) designs and compare the findings with clinical sequelae of capsular shrinkage. DESIGN: Comparative autopsy tissue study with clinicopathologic correlations. MATERIALS: Three hundred formalin-fixed human eyes containing the following PC-IOL styles were analyzed: (1) one-piece polymethyl methacrylate (PMMA) optic-PMMA haptic (n = 50), one-piece silicone-plate IOL, with large (2) or small (3) fixation holes (n = 35), (4) three-piece PMMA optic-Prolene haptic (n = 50), (5) three-piece acrylic optic-PMMA haptic (n = 55), three-piece silicone optic with PMMA (6) or polyimide (7) haptics (n = 30), and (8) three-piece silicone optic-Prolene haptic (n = 80) lenses. TESTING: The eyes were sectioned in the equatorial plane for gross examination of the capsular bag from a posterior view. The cornea and iris were then excised for evaluation from an anterior view. MAIN OUTCOME MEASURES: ACO was scored in each eye from 0 to IV, according to the degree/area of capsule opacification. Capsulorrhexis size and IOL decentration were measured with calipers. RESULTS: The overall differences among the IOL groups regarding the three parameters were significant (ACO score: P < 0.001; capsulorrhexis diameter: P = 0.036; IOL decentration: P = 0.012). Mean ACO scores were highest with the large- and small-hole one-piece silicone-plate lenses (2.543 +/- 0.950) and lowest with the three-piece acrylic optic-PMMA haptic lenses (0.600 +/- 0.710). Of 10 cases of capsulorrhexis phimosis observed in the study, 7 cases were associated with three-piece silicone optic-Prolene haptic lenses, which also presented the highest mean decentration (0.375 +/- 0.601 mm). CONCLUSIONS: Our results confirm previous histopathologic observations that the rate of ACO is the lowest with acrylic lenses and higher with plate-haptic silicone IOLs. Nevertheless, clinical sequelae of capsular shrinkage are also very important with three-piece silicone optic-Prolene haptic designs. Thus, IOL material and design are significant factors in the development of ACO, but they ultimately also influence the clinical presentation of capsular shrinkage.

Acrylic Resins↗

PubMed2001

[Postoperative opacification of posterior chamber intraocular lenses - a review].

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.

Biocompatible Materials↗

PubMed2001