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Biomedical subjects

M R Tetz

Publications and source records attributed to M R Tetz.

14 recordsLinked to original sources
PubMed1992

Results of extracapsular cataract extraction with intraocular lens implantation in eyes with uveitis and Fuchs' heterochromic iridocyclitis.

A total of 63 cataractous eyes of 48 patients (group 1) with uveitis and 12 eyes of 12 patients (group 2) with Fuchs' heterochromic iridocyclitis underwent extracapsular cataract extraction (ECCE) with capsular bag fixation of a posterior-chamber intraocular lens (PC OIL). A perioperative regimen of systemic dexamethasone (0.8-1.5 mg/kg) was initiated. This dose was tapered by 20 mg/day, reaching zero within 4-8 days. Intraoperatively, synechiolysis was required in 51 of 63 eyes in group 1 and a sector iridectomy was necessary in 42 eyes. A fibrinous reaction occurred in 7 eyes. During a mean follow-up period of 2 years, 7 eyes developed uveitis recurrences that were successfully treated with topical and systemic steroids in 4 eyes; the other 3 eyes developed cystoid macular edema. Overall, mean visual acuity improved from 20/120 to 20/50. Intraoperatively, 3 patients in group 2 developed a transient hemorrhage from atypical anterior-chamber-angle vessels. Postoperatively, 3 eyes showed a transient fibrinous reaction. The mean visual acuity improved from 20/240 to 20/30. In patients with Fuchs' heterochromic iridocyclitis, ECCE with PC IOL implantation renders good intermediate results. In other selected patients with uveitis, in-the-bag IOL implantation may be performed with an acceptable risk. As judged from their improved visual acuity, 57 of 63 eyes (90.5%) benefited from the procedure.

Adult↗
PubMed1992

Measurement of potential visual acuity in 343 patients with cataracts. A prospective clinical study.

In 343 patients with cataracts (the largest consecutive series in which this subject has been addressed) and 63 patients with clear optic media, who served as the control group, potential visual acuity was measured with the Guyton/Minkowski Potential Acuity Meter (PAM). The control group included 32 cases of macular degeneration, 22 cases of glaucoma, and 9 cases of amblyopia. The cataract group comprised 46 patients with macular degeneration, 46 with glaucoma, and 8 with amblyopia; 5-7 days postoperatively, corrected visual acuity was measured in this group. Because of dense cataracts in 59 patients, no PAM value could be obtained. The visual acuity of 70.4% of the patients, in whom complete data were obtained, was within one Snellen line of the predicted value or better (21%). In general, postoperative predictions were accurate in patients with moderate cataracts. The results were not affected by glaucoma or amblyopia. In 17.5% of patients with macular degeneration, false-positive results were obtained. The control group, in which distance visual acuity was compared with the PAM values, rendered comparable results, with 86.9% of the PAM predictions being correct.

Adult↗
PubMed1989

Protective effect of the anterior lens capsule during extracapsular cataract extraction. Part II. Preliminary results of clinical study.

In a clinical study, 61 patients underwent phacoemulsification with subsequent intraocular lens (IOL) implantation. An intercapsular capsulotomy with phacoemulsification was performed on 23 patients and a can opener capsulotomy with phacoemulsification on 38 patients. Wide-field specular microscopy was performed preoperatively and postoperatively on all of the eyes in the study. The cell counts were not divulged to the surgeon before or at the time of surgery. Average endothelial cell loss for the intercapsular technique was 3.9%; with the can opener technique, the average cell loss was 10.1%. This difference was statistically significant (P less than 0.01). Positive correlations between endothelial cell loss relating to ultrasound time and/or the hardness of the cataract existed for the can opener group only (P less than 0.01). These results demonstrate that a protective effect is provided by the presence of the anterior lens capsule during lens substance removal.

Aged↗
PubMed1989

Protective effect of the anterior lens capsule during extracapsular cataract extraction. Part I. Experimental animal study.

In an experimental study using albino Rex rabbits, the intercapsular cataract extraction (ICCE) technique was performed in 20 eyes with a small anterior capsulotomy. A large, can opener capsulotomy was performed in another 20 eyes, and 10 unoperated eyes served as controls. Endothelial cell loss was determined by vital staining with Trypan blue and Alizarin red S stains. Average endothelial cell loss with the ICCE technique was 1.2%; with the can opener technique, the average cell loss was 6.6%. This difference was statistically significant (P less than 0.01). The percentage of endothelial cell loss in the control eyes was 0.5. A positive correlation between endothelial cell loss related to phacoemulsification time and/or the amount of irrigating fluid used existed for the can opener group only (P less than 0.01). These results demonstrate that the presence of an almost intact anterior lens capsule during removal of lens substance is protective to the corneal endothelium.

Animals↗
PubMed1989

A method to study the interaction between intraocular lens loops and anterior segment vasculature.

Gold-coated plastic casts of the anterior segment ocular microcirculation of the rabbit eye were studied by scanning electron microscopy to define the interaction between ciliary sulcus fixated intraocular lenses and the anterior segment vasculature. A detailed description of the technique is given. Interactions such as loop deformation by the tissue and loop erosion into the vascular tissue are shown. Possible clinical applications of this experimental model are discussed.

Animals↗
PubMed1989

Infectious complications of modern cataract surgery and intraocular lens implantation.

Over one million intraocular lenses are implanted each year during cataract surgery in the United States alone. Despite an impressive overall success rate, infection remains an important postoperative complication. Virtually every microbial organism has the potential to be an intraocular pathogen, and this article addresses both generalized and localized forms of microbial endophthalmitis. Successful outcome requires prompt clinical recognition, appropriate laboratory evaluation, initiation of antimicrobial therapy, control of inflammatory sequelae, and when necessary, surgical intervention.

Bacterial Infections↗
PubMed1988

Decentration of flexible loop posterior chamber intraocular lenses in a series of 222 postmortem eyes.

Two hundred twenty-two postmortem eyes containing posterior chamber intraocular lenses (IOLs) were analyzed for optic decentration in relationship to lens style, implant duration, and loop fixation site. Decentration values were not affected significantly by either lens style or implant duration. In 33.3% of specimens, both loops were situated within the lens capsular sac, 18.0% had both loops fixated in the ciliary sulcus, and in 48.7% one loop was fixated in the lens capsular sac and the opposite loop in the ciliary sulcus or zonular region. There was a statistically significant difference in the amount of decentration in the three fixation groups studied. Capsular fixation provides the best and most consistent centration compared with fixation of both loops in the ciliary sulcus or asymmetrical fixation with only one loop in the capsular sac.

Ciliary Body↗
PubMed1988

Posterior capsular opacification and intraocular lens decentration. Part I: Comparison of various posterior chamber lens designs implanted in the rabbit model.

Experimental phacoemulsification procedures were performed in 54 Rex rabbits. In 96 eyes, posterior chamber intraocular lenses (IOLs) were implanted in the capsular sac, and 12 eyes served as controls with no lens implantation. The IOLs were divided into eight groups consisting of both one-piece and three-piece styles with various optic designs. Each lens was evaluated for the relative effect on posterior capsular opacification (PCO) and optic decentration, two of the most common complications of modern cataract surgery and IOL implantation. Optics with a convex-anterior, plano-posterior design (the type of IOL optic most frequently implanted today) had the highest incidence of PCO. With capsular fixated IOLs, the features that have a statistically significant impact on reducing PCO include (1) one-piece, all-polymethylmethacrylate (PMMA) IOL styles, (2) a biconvex or posterior convex optic design, and (3) angulated loops. Lens decentration was not affected by the optic design, but statistical analysis showed that one-piece, all-PMMA IOL construction provided the most consistent centration.

Animals↗
PubMed1988

Posterior capsular opacification and intraocular lens decentration. Part II: Experimental findings on a prototype circular intraocular lens design.

In a prospective randomized study, 25 New Zealand white rabbit eyes were implanted with four intraocular lens (IOL) designs. These included a one-piece modified J-loop IOL, a three-piece modified J-loop IOL, a rigid disc IOL, and an experimental compressible disc (CD) IOL. The CD IOL revealed the lowest mean posterior capsular opacification (PCO) of all IOLs tested (P less than .01). With all lenses tested, a positive correlation between PCO and decentration was found (R = 0.55, P less than .05). These results suggest that because of its design features (i.e., one-piece construction, biconvex optic, posterior angulation of the fixation element), the CD lens produces a mechanical barrier against lens epithelial cell migration and reduces the incidence of PCO.

Animals↗
PubMed1987

Localized endophthalmitis: a newly described cause of the so-called toxic lens syndrome.

We report five cases of post-extracapsular cataract extraction infection in which subsequent pathologic analyses identified the organisms and found the infection to be localized or confined to the lens capsular sac. The most common offending organisms were gram-positive pleomorphic bacilli. In one case, we were able to identify the bacteria as Propionibacterium acnes. We designate this condition a localized endophthalmitis. It should be considered any time a persistent, smoldering, postoperative inflammation occurs, and in the differential diagnosis of phacoanaphylactic endophthalmitis. The condition itself is not new, but undoubtedly many such cases have gone unrecognized or have been misdiagnosed as the so-called toxic lens syndrome. In localized endophthalmitis, a clinically visible inflammatory process may occur even when multiple diagnostic taps are negative, although when the cases first appeared, the surgeons were not aware of the entity and anaerobic cultures were not always obtained. A negative tap may be explained by the fact that metabolic products from the organisms are released from the bag into the anterior segment and vitreous. A synergistic reaction may occur between these organisms and retained lens cortical remnants that may cause or exacerbate a hypersensitivity reaction. The condition may be worsened by Nd:YAG capsulotomy. The pathogenesis of localized endophthalmitis has nothing to do with the type of intraocular lens fixation (lens capsular sac or ciliary sulcus); rather, the simple presence of a capsular sac after extracapsular cataract extraction is the prerequisite for the clinical condition.

Aged↗
PubMed1987

Anterior chamber lenses. Part I: Complications and pathology and a review of designs.

Clinicopathologic data to assist ophthalmologists in choosing a safe and efficacious anterior chamber intraocular lens (IOL) are rapidly becoming available. Two important factors that have led to an increased success rate with some anterior chamber IOL styles are (1) attention to lens design and (2) attention to modern manufacturing and lens finishing techniques. We now know much more about how to achieve appropriate lens flexibility, which decreases the need for perfect sizing. Increased attention has been given to the anterior-posterior vaulting characteristics of IOLs. This has reduced the incidence of various complications such as the intermittent touch syndrome and the uveal chafing syndrome. We recognize several design flaws in some lens styles. For example, there is now a considerable decrease in the number of small-diameter, round-looped anterior chamber IOLs being implanted, particularly those with a closed-loop configuration. Several problems have been and continue to be caused by some poorly manufactured anterior chamber lenses with sharp optic and haptic edges. Technology to assure smooth lens finishing and polishing is available and readily accessible to all manufacturers. Defective lenses should soon be a thing of the past.

Anterior Chamber↗
PubMed1987

Anterior chamber lenses. Part II: A laboratory study.

An analysis of 606 surgically removed anterior chamber intraocular lens (IOL) specimens revealed that 351 or 58% of these were small-diameter, round loop, closed-loop styles. Because of the extremely high percentage of IOLs with this design received in our laboratory and the correlation of clinical histories with our histopathologic findings, we have concluded that such IOLs do not provide the safety and efficacy achieved by other anterior chamber lens designs. The finely polished, one-piece, all-PMMA styles fared well in our study. Although these one-piece styles comprise well over 50% of the American market share of anterior chamber IOLs, they comprise only 14% of all anterior chamber IOLs accessioned in our laboratory, compared to 58% for closed-loop designs. We believe that implantation of anterior chamber lenses with small-diameter, round, closed loops is no longer warranted. Patients in whom these IOLs have already been implanted should be carefully followed. It is our opinion that the FDA should recall or closely monitor all IOLs of this design and that implantation of closed-loop lenses should be discontinued in the United States. Furthermore, we believe that an IOL deemed to be not medically sound or worthy of implantation in the United States should not be marketed or donated outside of this country.

Anterior Chamber↗
PubMedDate not supplied

Posterior capsule opacification.

A complication of extracapsular cataract extraction with or without posterior chamber intraocular lens (PC-IOL) implantation is posterior capsule opacification. This condition is usually secondary to a proliferation and migration of residual lens epithelial cells. Opacification may be reduced by atraumatic surgery and thorough cortical clean-up. Clinical, pathological and experimental studies have shown that use of hydrodissection, the continuous curvilinear capsulorhexis and specific IOL designs may help reduce the incidence of this complication. Capsular-fixated, one-piece all-polymethylmethacrylate PC-IOLs with a C-shaped loop configuration and a posterior convexity of the optic are effective. Polymethylmethacrylate loops that retain "memory" create a symmetric, radial stretch on the posterior capsule after in-the-bag placement, leading to a more complete contact between the posterior surface of the IOL optic and the taut capsule. This may help form a barrier against central migration of epithelial cells into the visual axis. Various pharmacological and immunological methods are being investigated but conclusive data on these modalities are not yet available.

Cataract↗