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Biomedical subjects

D T Azar

Publications and source records attributed to D T Azar.

At least 19 recordsLinked to original sources
PubMed2001

Amniotic membrane inlay and overlay grafting for corneal epithelial defects and stromal ulcers.

OBJECTIVES: To determine the effect of amniotic membrane transplantation (AMT) on persistent corneal epithelial defects (PEDs) and to compare the efficacy between inlay and overlay techniques. METHODS: Thirty patients (30 eyes) underwent AMT for PED. The use of AMT was restricted to patients in whom all previous measures, including bandage contact lens and tarsorrhaphy, had failed. The amniotic membrane was placed on the surface of the cornea in overlay (group A) or inlay (group B) fashion. RESULTS: The PED healed after the first AMT in 21 eyes (70%) within an average of 25.5 days after surgery and recurred in 6 eyes (29%). Among the 22 eyes treated with an overlay AMT (group A), the PED healed after the first AMT in 14 eyes (64%) within an average of 24.5 days and recurred in 4 eyes (29%). Among the 8 eyes treated with an inlay AMT (group B), the PED healed within an average of 27.4 days after AMT, which did not statistically significantly differ from group A (P = .72). The PED healed after the first AMT in 7 eyes (88%) and recurred in 2 (29%) of 7 eyes. CONCLUSIONS: The AMT can be helpful in the treatment of PED in which all other conventional management has failed. However, the success rate in our study was not as high as that previously reported, and our results showed a high incidence of recurrences of epithelial defects. We did not find any difference between overlay and inlay techniques in terms of healing time and recurrence rate.

Adult↗
PubMed2001

Phototherapeutic keratectomy for decentration and central islands after photorefractive keratectomy.

PURPOSE: To determine visual outcomes after treatment of decentration and central islands occurring after photorefractive keratectomy (PRK). DESIGN: Retrospective, noncomparative case series. PARTICIPANTS: Patients (n = 14) who exhibited decentration or central islands after PRK and photoastigmatic keratectomy (PARK). METHODS: Fourteen eyes with post-PRK decentration (group I) or central islands (group II) were treated by transepithelial phototherapeutic keratectomy guided by epithelial fluorescence without modulating agents, and subsequently were treated with PRK or PARK. Mean follow-up time was 9 months (range, 45 days-21 months). MAIN OUTCOME MEASURES: We analyzed pre- and postoperative keratometry, refractive errors, uncorrected visual acuity (UCVA), best-corrected visual acuity, and haze. In group I, we also measured pre- and postoperative decentration; in group II, we compared pre- and postoperative central island power. RESULTS: Group I showed improvement in centration (P = 0.003). Group II showed decreased central island power (P = 0.18). -LogMAR UCVA improved from 0.59 (20/80(+1)) to 0.17 (20/30) (P = 0.03) and from 0.74 (20/100(-1)) to 0.21 (20/30(-1)) (P = 0.01) after retreatment of groups I and II, respectively. CONCLUSIONS: Retreatment of patients having decentration and central islands after PRK results in improved visual outcomes.

Adult↗
PubMed2001

Posterior corneal surface changes after refractive surgery.

OBJECTIVE: To determine the frequency of changes in posterior corneal surface after laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). DESIGN: Nonrandomized, comparative trial. PARTICIPANTS: Ninety-five eyes (71 patients) that underwent PRK (n = 45) or LASIK (n = 50). CONTROLS: Twenty nonsurgery eyes were used to validate the method of analysis of the posterior corneal curvature (PCC). Seventy nonsurgery eyes were used for comparisons. METHODS: Float, apex-fixed best fit corneal curvature (ABC), and posterior elevation difference were evaluated in 20 elevation topography maps at 6 zone diameters (3-7 and 10 mm) and at two time points. Corneal elevation maps before and after PRK or LASIK were analyzed by the ABC and float methods and compared with a nonsurgery group. MAIN OUTCOME MEASURES: Posterior corneal curvature change (mm) was classified as flattening, steepening, or no change. RESULTS: Flattening of more than 0.12 mm was found in 22.2% of eyes (n = 10) in the PRK group, a change of +/-0.12 mm was found in 53.3% of eyes (n = 24), and steepening of more than 0.12 mm was found in 24.4% of eyes (n = 11) using the float method and in 28.9% of eyes (n = 13), 35.6% of eyes (n = 16), and 35.6% eyes (n = 16), respectively, using the ABC method. In the LASIK group, the float method registered flattening in 20% of eyes (n = 10), no change in 52% of eyes (n = 26), and steepening in 28% of eyes (n = 14), whereas the ABC method registered flattening in 30% of eyes (n = 15), no change in 40% of eyes (n = 20), and steepening in 30% of eyes (n = 15). The nonsurgery group showed a similar change in PCC at two different time points similar to that of the PRK and the LASIK groups. CONCLUSIONS: The differences observed in the PCC after PRK or LASIK were not statistically significantly different from those observed over time in the nonsurgery control group.

Adult↗
PubMed2001

Monovision outcomes in presbyopic individuals after refractive surgery.

PURPOSE: To characterize monovision outcomes and patient satisfaction with conventional monovision (dominant eye corrected for distance) and crossed monovision (dominant eye corrected for near) in presbyopic individuals after excimer laser photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). DESIGN: Retrospective observational case series. PARTICIPANTS: One hundred forty-four consecutive patients, 45 years or older, who were treated with excimer laser refractive surgery between December 1995 and June 1998. METHODS: Patients in whom the surgical outcome was monovision (MV) (distance vision spherical equivalent [SE] -0.50 to +0.50 diopter (D), near vision SE -3.75 to -1.00 D and anisometropia 1.00 D or greater), crossed MV (dominant eye corrected for near vision and the nondominant eye for distance vision) and full correction (bilateral SE -0.50 to +0.50) were identified. Data were abstracted and analyzed statistically. MAIN OUTCOME MEASURES: Preoperative and postoperative visual acuity and refraction. Patient satisfaction with monovision RESULTS: Forty-two patients had surgical outcome of MV. In MV patients, the average distance vision SE, near vision SE, and anisometropia were -0.04 +/- 0.27 D, -1.95 +/- 0.70 D, and 1.92 +/- 0.74 D, respectively. Patient satisfaction was 88% with MV. Twelve patients attained crossed MV. All patients with crossed MV were satisfied with their vision. Patient satisfaction with MV showed no relationship to gender, age at initial surgery, preoperative trial of monovision, laterality of treatment, type of monovision, or predictability of outcomes. CONCLUSIONS: Monovision may be a valuable option for presbyopic individuals considering refractive surgery. Crossed monovision can result in satisfactory visual outcomes.

Cornea↗
PubMed2001

Microkeratome-assisted posterior keratoplasty.

Microkeratome-assisted posterior keratoplasty is a new surgical technique that may be valuable in treating patients with corneal decompensation secondary to endothelial dysfunction. A hinged anterior stromal flap is fashioned in the host cornea using a microkeratome, and the diseased posterior stroma and endothelium are resected. A complementary donor stromal button is prepared using a microkeratome and an artificial anterior chamber. The donor button is transplanted and secured with sutures, and the flap is repositioned. The flap can be lifted later to remove the sutures or to correct residual refractive errors using an excimer laser. This technique may allow the use of infant corneal donor tissue and may improve the outcomes of posterior keratoplasty.

Aged↗
PubMed2001

Mitomycin C reduces corneal light scattering after excimer keratectomy.

PURPOSE: To evaluate the effect of intraoperative mitomycin C (MMC) on corneal light scattering after excimer laser keratectomy. METHODS: Phototherapeutic keratectomy (PTK) was performed in 24 rabbit eyes. After 40-microm epithelial ablation, animals were divided into three groups. In group 1, filter paper discs soaked with MMC (group 1A, 0.5 mg/mL; group 1B, 0.25 mg/ml) were applied for 1 minute. In group 2, annular filter papers soaked with MMC (group 2A, 0.5 mg/mL; group 2B, 0.25 mg/mL) were applied for 1 minute. Controls received vehicle only (group 3). Six-millimeter diameter 100-microm deep PTK was performed. Corneal light scattering was measured weekly from 1 to 6 weeks, at 10 weeks, and at 8 and 13 months using a scatterometer. A corneal light scattering index (SI) ranging from 0 to 10 was calculated; SI of 1 represents normal scattering. RESULTS: A statistically significant decrease in mean SI was noted in group 2A (annular MMC 0.5 mg/mL; p<0.05) as compared with the control group at 2 weeks. At 10 weeks, SI approached baseline levels in group 2 and the control group but showed significant increase in group 1 (MMC disc; p < 0.05). At 8 and 13 months, SI showed no statistical differences between groups. CONCLUSIONS: Controlled application of 0.5 mg/mL MMC in the corneal midperiphery transiently reduces corneal light scattering after excimer keratectomy in this rabbit model.

Alkylating Agents↗
PubMed2001

Survey of patients with granular, lattice, avellino, and Reis-Bücklers corneal dystrophies for mutations in the BIGH3 and gelsolin genes.

OBJECTIVES: To search for novel mutations that cause corneal stromal dystrophies and to confirm or revise the clinical diagnosis of patients with these mutations. PATIENTS: Through review of the records of the Cogan Eye Pathology Laboratory at the Massachusetts Eye and Ear Infirmary, Boston, and of clinical records, we ascertained 14 unrelated patients with the clinical or histopathologic diagnosis of granular (3 cases), Avellino (5 cases), lattice (5 cases), or Reis-Bücklers (1 case) corneal dystrophy. METHODS: Clinical records and histopathologic findings of the index patients and their relatives were reviewed. Patients and selected relatives donated a blood sample from which leukocyte DNA was purified and assayed for mutations in the BIGH3 gene and, in 2 patients, the gelsolin gene, using the polymerase chain reaction and direct genomic sequencing. RESULTS: All index patients with the diagnosis of granular dystrophy or Avellino dystrophy had the missense mutation Arg555Trp or Arg124His, respectively, previously reported in the BIGH3 gene. Of the 5 index patients with a prior diagnosis of lattice dystrophy, 2 had the originally reported lattice mutation (Arg124Cys) in the BIGH3 gene, 1 had a more recently reported missense mutation (His626Arg) in the same gene, 1 had the missense mutation Asp187Asn in the gelsolin gene, and 1 had no detected mutation in either gene. Affected members of the family with Reis-Bücklers dystrophy did not carry the previously reported mutations Arg555Gln or Arg124Leu but instead carried a novel missense mutation Gly623Asp in the BIGH3 gene. CONCLUSIONS: Molecular genetic analysis can improve the accuracy of diagnosis of patients with corneal dystrophies. Two patients with a prior diagnosis of lattice corneal dystrophy had their diagnosis changed to gelsolin-related amyloidosis (1 case) or secondary, nonhereditary localized amyloidosis (1 case). A novel mutation in the BIGH3 gene that causes Reis-Bücklers dystrophy was uncovered through this analysis, and another recently reported novel mutation was encountered. These findings serve to expand our knowledge of the spectrum of pathogenic mutations in BIGH3.

Adult↗
PubMed2001

Determination of corneal asphericity after myopia surgery with the excimer laser: a mathematical model.

PURPOSE: To determine the theoretical change of corneal asphericity within the zone of laser ablation after a conventional myopia treatment, which conforms to Munnerlyn's paraxial formula and in which the initial corneal asphericity is not taken into consideration. METHODS: The preoperative corneal shape in cross section was modeled as a conic section of apical radius R(1) and shape factor p(1). A myopia treatment was simulated, and the equation of the postoperative corneal section within the optical zone was calculated by subtracting the ablation profile conforming to a general equation published by Munnerlyn et al. The apical radius of curvature r(2) of the postoperative profile was calculated analytically. The postoperative corneal shape was fitted by a conic section, with an apical radius equal to r(2) and a shape factor p(2) equal to the value that induced the lowest sum of horizontal residuals and the lowest sum of squared residuals. These calculations were repeated for a range of different dioptric treatments, initial shape factor values, and radii of curvature to determine the change of corneal asphericity within the optical zone of treatment. RESULTS: Analytical calculation of r(2) showed it to be independent of the initial preoperative shape factor p(1). The determination of p(2) was unambiguous, because the same value induced both the lowest sum of residuals and the lowest sum of the squared residuals. For corneas initially prolate (p(1) < 1), prolateness increased (p(2) < p(1) < 1), whereas for oblate corneas (p(1) > 1), oblateness increased (p(2) > p(1) > 1) within the treated zone after myopia treatment. This trend increased with the increasing magnitude of treatment and decreased with increasing initial apical radius of curvature R(1). CONCLUSIONS: After conventional myopic excimer laser treatment conforming to Munnerlyn's paraxial formula, the postoperative theoretical corneal asphericity can be accurately approximated by a best-fit conic section. For initially prolate corneas, there is a discrepancy between the clinically reported topographic trend to oblateness after excimer laser surgery for myopia and the results of these theoretical calculations.

Cornea↗
PubMed2000

A new surgical technique of microkeratome-assisted deep lamellar keratoplasty with a hinged flap.

We describe a new surgical technique of microkeratome-assisted deep lamellar keratoplasty for treating patients with corneal stromal disease and normal endothelium. A microkeratome is used to create a hinged anterior stromal flap in the host cornea, and the diseased stroma is resected or ablated. A complementary donor stromal button, prepared using a microkeratome and an artificial anterior chamber, is transplanted prior to repositioning of the flap. The flap may be lifted at a later date, and an excimer laser used to correct residual refractive errors. Notwithstanding the preliminary and theoretical nature of this report, this technique may improve the outcomes of deep lamellar keratoplasty and may allow for decreased postoperative complications. Arch Ophthalmol. 2000;118:1112-1115

Corneal Diseases↗
PubMed2000

Late traumatic dislocation of laser in situ keratomileusis corneal flaps.

PURPOSE: To report the management and outcome of late-onset traumatic dislocation of laser in situ keratomileusis (LASIK) flaps. DESIGN: Retrospective, observational case series. PARTICIPANTS: Four patients with late-onset LASIK flap dislocation occurring after mechanical trauma at various intervals (10 days-2 months) after the procedure. INTERVENTION: In all cases of postoperative traumatic LASIK flap dislocation, the flap was refloated with scraping and irrigation of the underlying stromal bed within 12 hours of the injury. A bandage contact lens was placed, and a regimen including topical antibiotics and corticosteroids was instituted in all cases. MAIN OUTCOME MEASURES: Best spectacle-corrected visual acuity and complications associated with the surgery were monitored. RESULTS: Postoperative follow-up ranged from 4 to 21 months. Nonprogressive epithelial ingrowth was noted in one patient and diffuse lamellar keratitis developed in another patient. All patients recovered pretrauma spectacle-corrected visual acuity. CONCLUSIONS: Corneal LASIK flaps are prone to mechanical dislocation as late as 2 months after the procedure. Appropriate management results in recovery of optimal visual outcomes.

Adult↗
PubMed2000

Theoretical analysis of ablation depths and profiles in laser in situ keratomileusis for compound hyperopic and mixed astigmatism.

PURPOSE: To compare the theoretical ablation depths and profiles of 4 treatment strategies for compound hyperopic and mixed astigmatism. SETTING: Theoretical analysis. METHODS: Corneal contour drawings of theoretical corneal ablation profiles during laser in situ keratomileusis (LASIK) and photoastigmatic refractive keratectomy were made. The depths of tissue ablation in 4 treatment strategies for compound hyperopic astigmatism (Groups 1 to 4) and for mixed astigmatism (Groups 5 to 8) were compared: (1) combined hyperopic spherical and myopic cylindrical treatments (Groups 1 and 5); (2) combined spherical and hyperopic cylindrical treatments (Groups 2 and 6); (3) combined cylindrical treatments (Groups 3 and 7); (4) combined cross-cylinder and spherical equivalent treatments (Groups 4 and 8). RESULTS: In compound hyperopic astigmatism, the 4 approaches resulted in identical final curvatures, but the ablation depths were greatest in Group 1 (combined hyperopic spherical and myopic cylindrical treatments). The smallest amount of ablation occurred in Group 2 (combined hyperopic spherical and hyperopic cylindrical treatments) and Group 3 (combined hyperopic cylindrical treatments), which had similar tissue ablation patterns. In mixed astigmatism, the greatest ablation depth was in Group 5, followed by Group 8, and Groups 6 and 7. The tissue ablation depths and profiles were similar in Groups 6 and 7. CONCLUSION: The treatment approaches in Groups 2, 3, 6, and 7 (which avoided the use of minus cylinder) resulted in the smallest degree of stromal ablation. Patients with compound hyperopic or mixed astigmatism may benefit from reduced ablation depths by deferring treatment until hyperopic cylindrical and/or combined cylindrical treatments are available.

Astigmatism↗
PubMed2000

Outcome of corneal and laser astigmatic axis alignment in photoastigmatic refractive keratectomy.

PURPOSE: To compare the refractive results of laser astigmatic treatment in eyes in which the astigmatic axes of the eye and laser are aligned by limbal marking at the 6 o'clock position and in eyes that are not marked. SETTING: University Hospital and Clinics, Madison, Wisconsin, USA. METHODS: This retrospective study comprised 143 eyes that had photoastigmatic refractive keratectomy with the VISX Star excimer laser. The eyes were divided into marked (G1) and unmarked (G2) groups. Based on the preoperative astigmatism, each group was subdivided into low astigmatism (</=1.00 diopter [D]) and high astigmatism (>/=1.25 D). Early postoperative manifest refractions (1.0 to 2.5 months) were analyzed. The Alpins vector analysis method was used to calculate the target induced astigmatism, surgically induced astigmatism, difference vector (DV), magnitude of error (ME), angle of error (AE), and index of success (IS). RESULTS: There was no significant difference between the groups in DV, ME, and IS. When the subgroups were analyzed, the DV and ME were comparable; the IS in the G1 high astigmatism subgroup was significantly better than that in the G2 high astigmatism subgroup (0.22 +/- 0.08 and 0.29 +/- 0.04, respectively; P <.0001). There was comparable scatter of AE values; 30% and 36% in G1 and G2, respectively, had an AE of 0. Similar scatter was observed in the subgroups. Of the eyes that had an AE of 0, 90% and 43% in the high astigmatism subgroups of G1 and G2, respectively (P <.05), had full correction of astigmatism. CONCLUSION: Limbal marking and subsequent eye and laser astigmatic axis alignment improved the refractive outcome of laser astigmatic treatment of >/=1.25 D. A preliminary report of an ongoing prospective randomized study of eyes that had laser in situ keratomileusis is included.

Adult↗
PubMed2000

Differential expression of MT1-MMP (MMP-14) and collagenase III (MMP-13) genes in normal and wounded rat corneas.

PURPOSE: Several members of the matrix metalloproteinase (MMP) group have been identified in the rat cornea during corneal wound healing. The aim of the present study was to identify additional members of the MMP gene family in the rat cornea and localize the expression of membrane type-1 matrix metalloproteinase (MT1-MMP; MMP-14) and collagenase III (MMP-13) in normal and wounded corneas. METHODS: Adult rats underwent laser keratectomy on the right eye. Unwounded left eyes were normal controls. Corneas were collected and processed at different times post-wounding. Reverse transcription-polymerase chain reaction (RT-PCR) and DNA sequencing were used to discover the MMP genes expressed in the corneas. In situ hybridization was performed to localize the mRNA expression of MMP-14 and MMP-13. RESULTS: MMP-13 mRNA was detected in epithelial cells of wounded corneas, but not in normal controls; MMP-14 was found in both normal and wounded corneas. MMP-14 mRNA was expressed predominantly in the stromal keratocytes and rarely in the basal epithelial cells in normal and wounded corneas. MMP-13 mRNA was localized exclusively to basal cells of the epithelium at the wounded area from 6 hours to 3 days after wounding. CONCLUSIONS: MMP-14 and MMP-13 expression in rat corneas parallels that of gelatinases A and B, respectively. MMP-13 may play an important role in the gelatinase B-associated proteolytic cascade that allows rapid turnover of the extracellular matrix (ECM) components during corneal wound healing. MMP-14 may contribute to removing abnormal ECM components through activation of gelatinase A in rat corneas.

Animals↗