Search PubMed⌕ Search

Biomedical subjects

D T Azar

Publications and source records attributed to D T Azar.

69 records · Page 4Linked to original sources
PubMed1992

Simultaneous corneal laceration repair, cataract removal, and posterior chamber intraocular lens implantation.

Frequently, patients with lens laceration or traumatic cataract coincident with corneal laceration, or both, must undergo two separate procedures-primary repair of the corneal laceration and secondary lens removal with or without intraocular lens implantation. We performed simultaneous corneal laceration repair, extracapsular cataract extraction, and posterior chamber lens implantation in seven patients with lacerating ocular injuries who met inclusion criteria for this procedure. With average follow-up of 10 1/2 months, all seven patients achieved visual acuity of 20/40 or better with spectacle correction. YAG posterior capsulotomy was the only additional procedure. One patient had macular pigmentation consistent with either traumatic or photic maculopathy. There were no other complications attributable to the surgical procedures. We believe that certain lacerating injuries of the anterior segment are particularly amenable to cataract extraction and lens implantation at the time of primary laceration repair. This approach obviates additional operative and anesthetic risks, while affording more timely visual rehabilitation.

Adult↗
PubMed1992

Altered epithelial-basement membrane interactions in diabetic corneas.

Morphologic alterations of the extracellular matrix in diabetes include thickening of the basement membrane and, as evidenced in the corneal epithelium, a decrease in the area of the basal cell membrane occupied by hemidesmosomes. To determine if the abnormal basement membrane in diabetes has altered epithelial recognition of sites for hemidesmosome formation and if diabetic epithelium can recognize sites for hemidesmosome formation on normal basement membrane, we recombined epithelial sheets and corneal stromas with denuded basement membranes in vitro using diabetic and control corneas. In recombinations of diabetic epithelium on normal stromas, the area of the basal cell membrane occupied by hemidesmosomes was 10.7%, significantly less than control recombinations (19.5%). Similarly, in recombinations of normal epithelium on diabetic stromas, the value (8.6%) was significantly decreased from control. These data may indicate altered cell-extracellular matrix interactions in diabetes.

Animals↗
PubMed1991

Reassembly of the corneal epithelial adhesion structures following human epikeratoplasty.

Ten epikeratoplasty lenticules removed after surgery were obtained for immunohistochemical and electron microscopic analysis to determine the pattern of re-formation of corneal epithelial adhesion structures. Antibodies to laminin and type VII collagen were used to determine the presence of basement membrane and anchoring fibrils, respectively. Electron micrographs were used to determine the percentage of basal cell membrane occupied by hemidesmosomes, the area of basal lamina per 100 microns of basal cell membrane, and the average maximum depth of penetration of anchoring fibrils into the stoma. Nine normal corneas served as controls. Compared with normal corneas (24.5% of basal cell membrane occupied by hemidesmosomes; 32.0 microns 2 basal lamina per 100 microns of basal cell membrane), lenticules removed for optical reasons had near-normal hemidemosomes as early as 10 weeks following surgery (mean, 20.3%). The area of basement membrane was reduced (16 microns 2 basal lamina per 100 microns of basement cell membrane). During the course of 2 to 3 years, irregularities and duplications of the basement membrane were noted. Compared with normal corneas, the two lenticules removed for persistent defects had a marked reduction of hemidesmosomes and basement membrane present under epithelium at 3 and 4 weeks (9.6% of basal cell membrane occupied by hemidesmosomes and 13.6 microns 2 basal lamina per 100 microns of basal cell membrane, and 5.4% of basal cell membrane occupied by hemidesmosomes and 7.2 microns 2 basal lamina per 100 microns of basal cell membrane, respectively.

Adult↗
PubMed1989

Decreased penetration of anchoring fibrils into the diabetic stroma. A morphometric analysis.

Morphometric measurements of epithelial adhesion structures were performed on electron micrographs of corneas of diabetic patients (ages 35 to 77 years) and controls of similar age (ages 21 to 79 years). Penetration of the anchoring fibrils from the deepest layer of the basal lamina into the stroma was significantly decreased in diabetics (0.41 +/- 0.02 microns) compared with controls of similar ages (0.65 +/- 0.03 microns). Significant thickening of the basal lamina in diabetics (50.1 +/- 7.6 microns 2/100 microns basal cell membrane) was noted compared with controls (32.0 +/- 6.3 microns 2/100 microns), but no significant differences were noted in the percentage of the basal cell membrane occupied by hemidesmosomes. Decreased penetration of the anchoring fibrils into the stroma may cause the loose adhesion between the stroma and basement membrane observed in diabetes.

Adult↗
PubMed1989

Repair of the corneal epithelial adhesion structures following keratectomy wounds in diabetic rabbits.

In corneal tissue from a diabetic patient 15 months after delayed epithelial healing following vitrectomy surgery, electron microscopy revealed a discontinuous basement membrane; immunohistochemically, fibronectin was present in the basement membrane zone. To determine whether alterations in repair of the basement membrane, anchoring fibrils and hemidesmosomes occur in wounds in diabetics, we studied the pattern of histochemical localization of bullous pemphigoid antigen (the intracellular hemidesmosome plaque component), laminin and type VII collagen (the anchoring fibril collagen) in alloxan-induced diabetic rabbits following superficial keratectomy. Ultrastructural studies of basal laminae and hemidesmosomes also were performed. Epithelial wound closure was complete by 66-72 h after 7-mm superficial keratectomies. Type VII collagen localized at the base of the epithelium at the wound periphery by 66 h, appearing as a beaded line underlying the epithelium; at 1 week, as in control rabbits, the localization zone extended across the wound bed. Polyclonal antibodies to laminin and bullous pemphigoid antigen showed similar localization. Small segments of basal laminae were noted by electron microscopy of the wound periphery as early as 66 h post-keratectomy. By 2 weeks, an increase in hemidesmonsomes associated with segments of discontinuous basal lamina was apparent. No obvious differences in the time or pattern of re-appearance of the adhesion complex in keratectomy wounds could be discerned between normoglycemic and hyperglycemic rabbits. Thus, healing defects in diabetics may be due to factors other than reassembly of adhesion structures.

Adult↗
PubMed1988

A-scan ultrasonography in the diagnosis of orbital dermoid cysts.

Eleven patients with anterior and deep orbital masses had A-scan ultrasonography. The ultrasonograms were all similar and demonstrated a dermoid-like pattern of low internal reflectivity and a high-rising, double-peaked posterior surface spike. Although the postoperative pathologic findings in seven cases confirmed the clinical diagnosis of dermoid cyst, other lesions, such as epidermoid cyst, sebaceous cyst, Graves's myopathy, and Ewing's sarcoma were found to show a similar ultrasonographic pattern. This stresses the importance of computed tomography in the diagnosis of orbital tumors.

Adolescent↗
PubMed1986

Comparative aqueous outflow facility measurements by pneumatonography and Schiotz tonography.

Tonography was performed on 36 eyes of 15 normal and 3 primary open angle glaucoma patients using pneumatonography and classical Schiotz tonography. The average values of the coefficient of outflow facility (C) for the whole sample were virtually identical with both methods. However, both intersubject and interobserver variability were significantly higher with penumatonography. Although both methods provide comparable aggregate estimates of aqueous outflow facility, we think that Schiotz tonography is more reliable than pneumatonography because of the greater mechanical stability of the Schiotz instrument on the eye. On the other hand, pneumatonography offers the advantage of a shorter test period (2 min instead of 4).

Adult↗
PubMed1985

Reversible visual loss following optic nerve injury.

A case of shrapnel injury to the optic nerve documented by computed tomography, resulting in total, but partially reversible visual loss, is presented. In view of the visual field defect and computed tomographic findings, a transient vascular insult is incriminated. The irreversible loss in the lower field of vision is related to the shearing effect of trauma on the vulnerable pial vessels supplying the upper half of the nerve.

Adolescent↗
PubMedDate not supplied

The use of confocal microscopy in evaluating corneal wound healing after excimer laser keratectomy.

Corneal wound healing following excimer laser keratectomy is the major cause of regression of treatment results. The amount of anterior stromal haze that develops may be influenced by topical medications. Over a period of 6 months, we followed 15 New Zealand white rabbit eyes that underwent excimer laser keratectomy with the VISX 193-nm ArF laser at a fluence of 150 mJ/cm2 for a depth of 130 microns. Eyes were randomized to treatment with prednisolone acetate, diclofenac sodium (Voltaren), a combination of both, and a control group. Drops were administered four times a day for 1 week, two times a day for 3 weeks, and the drops were then tapered. All eyes were reepithelialized by 5 to 7 days. The tandem scanning confocal microscope (TSCM) was used to evaluate the corneal wound in vivo weekly for a month and monthly for 6 months. During the early postoperative period, the TSCM revealed significant anterior stromal keratocyte activation with cell elongation and the spindle-shaped appearance of fibroblasts in all groups. Collagenous stromal scarring was evident initially, then slowly decreased in all treatment groups. This study shows that TSCM is clinically useful for successive in vivo examinations of corneal wounds after excimer laser keratectomy and for comparing the effects of various topical medications.

Animals↗
PubMedDate not supplied

LASIK complications: etiology, management, and prevention.

Laser in situ keratomileusis (LASIK) is a rapidly evolving ophthalmic surgical procedure. Several anatomic and refractive complications have been identified. Anatomic complications include corneal flap abnormalities, epithelial ingrowth, and corneal ectasia. Refractive complications include unexpected refractive outcomes, irregular astigmatism, decentration, visual aberrations, and loss of vision. Infectious keratitis, dry eyes, and diffuse lamellar keratitis may also occur following LASIK. By examining the etiology, management, and prevention of these complications, the refractive surgeon may be able to improve visual outcomes and prevent vision-threatening problems. Reporting outcomes and mishaps of LASIK surgery will help refine our approach to the management of emerging complications.

Cornea↗
PubMedDate not supplied

Success of monovision in presbyopes: review of the literature and potential applications to refractive surgery.

The monovision concept of correcting one eye for distance and the other for near may be utilized in presbyopes undergoing refractive surgery. We have performed a systematic review of published literature to evaluate the factors influencing monovision success, and to determine the visual outcome in patients with monovision. Articles in MEDLINE and published bibliographies reporting monovision prescription for correction of presbyopia were systematically identified and reviewed. Pertinent data were abstracted and, when feasible, statistically analyzed. The mean success rate was 73%. The success in monovision correlated with distance correction on dominant eye, alternating dominance, less than 50 seconds of are stereoacuity reduction, and less than 0.6 prism diopter of distance esophoric shifts. Monovision resulted in significant reduction of binocular contrast sensitivity function at spatial frequencies higher than 4 cycles per degree, and 2-6% reduction in task performance, but resulted in minimal reduction of binocular visual acuity, peripheral vision, visual field width and binocular depth of focus. The published literature indicates that monovision is an effective and reasonable therapeutic modality for correcting presbyopia. Proper patient selection and clinical screening are essential for monovision success.

Adult↗
PubMedDate not supplied

Eye infections after refractive keratotomy.

BACKGROUND: Ocular infections are serious and potentially vision-threatening complications of refractive keratotomy. We have performed an integrative review of published literature to address important issues concerning these complications. METHODS: Articles in MEDLINE and published manuscripts and abstracts reporting previously unpublished cases of infections after refractive keratotomy were systematically identified and reviewed. Our review did not target patients treated with relaxing incisions for postkeratoplasty astigmatism. Pertinent data were abstracted and analyzed. RESULTS: Forty-three cases (47 episodes: 42 keratitis and 5 endophthalmitis) of infection appeared in 26 published reports from 1975 to 1994. The frequency ranged from 0.25% to 0.70%. In 22 (47%) eyes, infection occurred before 2 weeks. Thirty-five (74%) infections were located in the inferior half of the cornea, and 22 (62%) were located in the inferotemporal quadrant. Thirty-one (66%) infections were bacterial (32% gram-positive, 23% gram-negative, 9% acid fast, 496 unknown), 5% fungal, 6% viral, 19% sterile, and 4% of unknown origin. Spectacle-corrected visual acuity after conservative treatment was 20/40 or better in 70% of eyes. Penetrating keratoplasty was performed in six cases. Potential associations included reoperations in 12 (26%) eyes, postoperative contact lens wear in 7 (15%), and intraoperative perforation in 7 (15%). CONCLUSIONS: The published literature indicates that infections after refractive keratotomy may compromise visual function. Approximately half of the infections occur in the first 2 weeks. Reoperations, postoperative contact lens wear, and intraoperative perforations may be significant risk factors.

Contact Lenses↗
PubMedDate not supplied

Excimer laser calibration system.

BACKGROUND: Excimer laser photoablation for refractive and therapeutic keratectomies has been demonstrated to be feasible and practicable. However, corneal laser ablations are not without problems, including the delivery and maintenance of a homogeneous beam. We have developed an excimer laser calibration system capable of characterizing a laser ablation profile. METHODS: Beam homogeneity is determined by the analysis of a polymethylmethacrylate (PMMA)-based thin-film using video capture and image processing. The ablation profile is presented as a color-coded map. Interpolation of excimer calibration system analysis provides a three-dimensional representation of elevation profiles that correlates with two-dimensional scanning profilometry. Excimer calibration analysis was performed before treating a monkey undergoing phototherapeutic keratectomy and two human subjects undergoing myopic spherocylindrical photorefractive keratectomy. Excimer calibration analysis was performed before and after laser refurbishing. RESULTS: Laser ablation profiles in PMMA are resolved by the excimer calibration system to .006 microns/pulse. Correlations with ablative patterns in a monkey cornea were demonstrated with preoperative and postoperative keratometry using corneal topography, and two human subjects using video-keratography. Excimer calibration analysis predicted a central-steep-island ablative pattern with the VISX Twenty/Twenty laser, which was confirmed by corneal topography immediately postoperatively and at 1 week after reepithelialization in the monkey. Predicted central steep islands in the two human subjects were confirmed by video-keratography at 1 week and at 1 month. Subsequent technical refurbishing of the laser resulted in a beam with an overall increased ablation rate measured as microns/pulse with a donut ablation profile. A patient treated after repair of the laser electrodes demonstrated no central island. CONCLUSIONS: This excimer laser calibration system can precisely detect laser-beam ablation profiles. The calibration system correctly predicted central islands after excimer photoablation in a treated monkey cornea and in two treated human subjects. Detection of excimer-laser-beam ablation profiles may be useful for precise calibration of excimer lasers before human photorefractive and therapeutic surgery.

Animals↗
PubMedDate not supplied

Effect of punctal occlusion by Freeman silicone plug insertion on tear osmolarity in dry eye disorders.

We retrospectively examined the effect of punctal occlusion by Freeman silicone plug insertion on dry eye disorders in 17 patients. Patients met at least two of the following criteria: history consistent with dry eye, interpalpebral rose bengal staining, and elevated tear film osmolarity. Plug insertion significantly decreased tear film osmolarity. Rose bengal staining decreased in 75% of the eyes examined. There were no cases of postoperative epiphora. Punctal plug insertion is therapeutic for dry eye disease, but extrusion is a significant problem.

Adult↗