Search PubMed⌕ Search

Biomedical subjects

D J Apple

Publications and source records attributed to D J Apple.

At least 163 records · Page 9Linked to original sources
PubMed1991

The relationship between the stretching capability of the anterior capsule and zonules.

The stretching capability of the zonules was studied in 40 human eyes obtained postmortem from 27 patients. A continuous circular capsulorhexis (CCC) (2.2-6.8 mm) was performed, and the lenses were removed by either phacoemulsification (26 eyes) or planned extracapsular cataract extraction (ECCE) (14 eyes). Maximal zonular stretch was calculated as the difference in distance between the ciliary processes and the zonular insertion at rest and after maximal stretch. This zonular stretch test showed that zonules can stretch to a mean distance of 3.82 mm before rupturing. Capsular elasticity was measured in 35 of the eyes by gradually opening a modified caliper until the capsular opening was torn. The ratio between the circumference at rupture and the circumference at rest was used as an index of capsular elasticity. Circumference of the intact capsulorhexis could be enlarged an additional 62% before a radial tear occurred. In most cases, no significant correlation was seen between the capsular and zonular capability to stretch. Maximal zonular stretch decreased significantly with age by approximately 0.5 mm for every 5 yr, whereas capsular elasticity did not show a significant correlation with age. Two eyes with pseudoexfoliation had relatively friable zonules but the capsular elasticity was within normal limits. Patient age is probably the best indicator of the stretching capability of the zonules.

Age Factors↗
PubMed1990

Preparation and study of human eyes obtained postmortem with the Miyake posterior photographic technique.

A modification of the original Miyake technique of posterior photography of human eyes obtained postmortem is presented. A detailed description of globe preparation and equipment is described. Use of modern technology including a high magnification microscope system and video camera permits dynamic or realtime observations of tissue effects of various surgical procedures such as the cataract operation. This technique provides both a research and educational tool that can be used by ophthalmologists to improve the quality of surgery. Most important, it is an instructional tool that should reduce the "learning curve" that is inherent when modifying one's surgical technique.

Eye↗
PubMed1989

Sutured retropupillary posterior chamber intraocular lenses for exchange or secondary implantation. The 12th annual Binkhorst lecture, 1988.

The histopathologic findings of four eyes obtained postmortem with iris-sutured posterior chamber intraocular lenses (PC IOLs) are described. These IOLs were implanted as exchange procedures. In most instances, the loops were not situated in the ciliary sulcus but rather were suspended behind the iris and ciliary body. Therefore, the primary mechanism of fixation of iris-sutured PC IOLs appears to be the sutures themselves rather than adherence to the ciliary tissues. This report of four eyes is preliminary, but the pathologic analysis, showing few significant lesions attributable to the IOL, provides a reason for optimism for using this technique. A long-term clinical study comparing the results of sutured PC IOLs with those of anterior chamber IOLs (AC IOLs) used in secondary or exchange implantation, as well as collection and analysis of more pathologic specimens, should provide a more definitive answer as to the preferred procedure.

Aged↗
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

Evaluation of the biocompatibility and fixation of a new silicone intraocular lens in the feline model.

The biocompatibility and fixation of a new silicone intraocular lens was evaluated in the cat eye. Following extracapsular lens extraction, 14 cats were implanted with a silicone lens (SLM 2/UV type) with polypropylene modified J loops in one eye and a poly(methyl methacrylate) (PMMA) lens (Perspex CQ) of a similar design in the fellow eye. Half the lenses were placed in the ciliary sulcus and half in the capsular bag. The eyes were evaluated for up to one year. Neither lens material showed any signs of toxicity clinically or histopathologically. Both lenses achieved stable fixation in the capsular bag; however, some inflammatory reaction and lens dislocation were noted with sulcus placement of both lens types. The amount of proteinaceous and cellular debris on the explanted silicone lenses was significantly less than that on the PMMA lenses as assessed with methylene blue staining. All retrieved lenses were optically clear and no significant change in the lens surface morphology, clarity and/or optical properties was observed.

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↗
PubMed1989

[Protective effect of the anterior lens capsule: corneal endothelial cell loss following intercapsular phacoemulsification compared with phacoemulsification with large open capsulotomy].

In an experimental study using rabbits, the intercapsular technique was performed in 20 eyes to make a small anterior capsulotomy. A large, "can opener" capsulotomy was performed in 20 eyes, and ten eyes (five non-operated animals) served as controls. Endothelial cell loss was determined by vital staining with Trypan blue and Alizarin red S. Average endothelial cell loss with the intercapsular technique was 1.2%; with the can opener technique the cell loss was 6.6%. This difference was statistically significant (p less than 0.01). The percentage in the control eyes was 0.05%. Positive relations 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↗
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↗
PubMed1988

Simultaneous bilateral conjunctival and orbital lymphoma presenting as a conjunctival lesion.

A 44-year-old man with the diagnosis of a conjunctival lymphoma in the left eye was also found on further evaluation to have a lymphoma in the opposite orbit. The patient had no systemic signs of the disease, and was treated with localized radiation therapy. Although simultaneous presentation of lymphoma affecting the conjunctiva in one eye and the orbit on the opposite side is rare, any patient with an isolated conjunctival lymphoma should have a careful evaluation of the opposite eye and orbit, including an orbital computed tomographic scan to rule out simultaneous involvement.

Adult↗
PubMed1988

Surgical removal of an "inoperable" neurofibroma.

An 8-month-old girl had ipsilateral ptosis, proptosis, and glaucoma caused by a massive left-sided plexiform neurofibroma. The tumor extended from the cavernous sinus into the orbit, involving the optic nerve, extraocular muscles, and eyelid. Although the prognosis in such cases is considered very poor, most of the mass was excised by a radical neurosurgical and ophthalmologic procedure. Today, the patient remains asymptomatic with no further neurologic defects. This case is unusual in that the glaucoma developed prior to clinically evident eyelid involvement.

Blepharoptosis↗