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Biomedical subjects

Michael W Belin

Publications and source records attributed to Michael W Belin.

8 recordsLinked to original sources
PubMed2006

Results from the multicenter Boston Type 1 Keratoprosthesis Study.

PURPOSE: To report indications, practices, complications, and outcomes from the first multicenter study on the Boston Type 1 keratoprosthesis. DESIGN: Prospective, noncomparative, interventional case series. PARTICIPANTS: We analyzed 141 Boston Type 1 keratoprosthesis surgical procedures, from 17 surgical sites, done from January 2003 through September 2005 in 136 eyes of 133 patients. METHODS: Forms reporting 70 preoperative, intraoperative, and postoperative parameters were collected and analyzed at a central data collection site (Cornea Consultants of Albany, Albany Medical College, Albany, New York). MAIN OUTCOME MEASURES: Visual acuity (VA) and keratoprosthesis survival. RESULTS: Common preoperative diagnoses were graft rejection, in 73 eyes (54%) (average prior grafts, 2.24); chemical injury (20 eyes [15%]); bullous keratopathy (19 eyes [14%]); and herpes simplex virus keratitis (9 eyes [7%]). Additionally, 82 eyes (60%) had preoperative glaucoma. Preoperative best-corrected VA ranged from 20/100 to light perception, and was <20/200 in 96% of eyes. At an average follow-up of 8.5 months (range, 0.03-24; standard deviation, 6.1; median, 12), postoperative vision improved to > or =20/200 in 57%. Among eyes at least 1 year after the operation (62 eyes), vision was > or =20/200 in 56% of eyes and > or =20/40 in 23%. At an average follow-up of 8.5 months, graft retention was 95%. Severe visual loss or failure to improve from keratoprosthesis was usually secondary to comorbidities such as advanced glaucoma, macular degeneration, or retinal detachment. CONCLUSIONS: The Boston Type 1 keratoprosthesis seems, based on early follow-up, to be a viable option after multiple failed corneal grafts or in some situations of a poor prognosis for primary penetrating keratoplasty.

Cornea↗
PubMed2006

Changes in the posterior cornea after laser in situ keratomileusis and photorefractive keratectomy.

PURPOSE: To study the changes in posterior corneal elevation after laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) using Scheimpflug topography with the Pentacam anterior segment imaging system (Oculus, Inc.). SETTING: Department of Ophthalmology, Albany Medical Center, and a private clinical practice, Albany, New York, USA. METHODS: In this prospective study, 121 consecutive myopic eyes (103 LASIK and 18 PRK) were evaluated preoperatively and postoperatively with the Pentacam to determine elevation changes in the posterior corneal surface. Changes in posterior elevation were calculated by comparing the best-fit sphere preoperatively and postoperatively to a fixed reference sphere using the central 9.0 mm preoperative cornea. Statistical and graphic analyses were performed. RESULTS: The 103 LASIK eyes had a mean correction of -3.76 diopters (D) and a mean ablation depth of 62.1 microm. The mean estimated residual bed thickness (RBT) (329 microm) demonstrated a mean posterior displacement of 2.64 +/- 4.95 microm. The 18 PRK eyes had a mean correction of -2.69 D and a mean ablation depth of 53.2 microm. The mean estimated RBT (464 microm) had a mean posterior displacement of -0.88 +/- 4.64 microm. The difference in the mean posterior corneal displacement between the LASIK and the PRK eyes was not statistically significant (P>.05, Student t test). CONCLUSIONS: There was no statistically significant difference in posterior corneal displacement between the LASIK and PRK patients. The changes in PRK and LASIK eyes appeared to be within acceptable measurement variation. Contrary to previous reports, ectatic changes to the posterior corneal surface did not routinely occur after LASIK surgery.

Cornea↗
PubMed2006

Clinical profile and early surgical complications in the Cornea Donor Study.

PURPOSE: The Cornea Donor Study was designed to investigate the safety and efficacy of older donor corneal tissue compared with younger donor tissue in recipient eyes at moderate risk to the graft from progressive endothelial failure. Baseline patient data, including indications for transplant, intraoperative complication rates, and early postoperative complication rates are described herein. METHODS: This study was a multicenter prospective, double-masked, controlled clinical trial. RESULTS: Fuchs dystrophy was the most common indication for corneal transplantation (61%). Intraoperative complications occurred in 33 (3%) patients. A persistent epithelial defect was the most commonly reported postoperative complication, occurring in 92 patients (8%). CONCLUSION: Intraoperative and postoperative complication rates were low. There was no apparent association between donor or recipient age and either intraoperative or early postoperative complication rates.

Adult↗
PubMed2006

Thin head and single use microkeratomes reduce epithelial defects during LASIK.

PURPOSE: To evaluate the effect of microkeratome design and head dimension (flap thickness) on the rate of epithelial defects. METHODS: A retrospective review of 4000 LASIK procedures performed between May 2000 and December 2003 was conducted. Intraoperative epithelial defects were identified in 326 cases. The microkeratome design (reusable vs disposable) and head dimensions (100, 130, and 150 micron) were recorded along with age, sex, central ultrasonic pachymetry, keratometry, preoperative refraction (sphere, cylinder, and axis), and Schirmer testing. The chi-square and Student t test were used in data analysis. RESULTS: A total of 326 (8.2%) procedures had an associated epithelial defect. With the reusable microkeratome, heads that produced thinner flaps were associated with a lower incidence of epithelial defects (P<.05 for all three groups, 100, 130 and 150 micron head). When compared to a reusable head of the same dimension and to the entire population of reusable heads, the disposable 130 head exhibited a significantly lower rate of epithelial defects (P<.0001). CONCLUSIONS: The results of this study support that both microkeratome design and head dimension (and resulting corneal flap thickness) play a role in the formation of epithelial defects. These are surgeon selectable factors, unrelated to technique or patient risk factors, which can be used to reduce the rate of epithelial defects and associated complications.

Adolescent↗
PubMed2004

Confocal microscopy: a report by the American Academy of Ophthalmology.

OBJECTIVE: To review the available evidence for the use of confocal microscopy in diagnosing infectious keratitis and for other applications for ophthalmic practice. METHODS: A MEDLINE search of the peer-reviewed literature for the years 1990 to 2001 yielded 94 citations. The search was limited to studies of human subjects published in English with abstracts. The Ophthalmic Technology Assessment Committee Cornea Panel evaluated these 94 articles for possible clinical relevance and selected 51 (54%) for content review by the panel members. Of these 51 articles, 24 were selected for the panel methodologist to review and rate according to the strength of evidence. RESULTS: Of the 24 articles, 21 (87.5%) were classified as case reports or case series and were rated as level III evidence. Three articles were classified as independent, masked, or objective comparisons performed in a narrow spectrum of patients or in a nonconsecutive series of patients and were rated as level II evidence. No studies were rated as level I evidence, defined as an independent masked comparison of an appropriate spectrum of consecutive patients. CONCLUSION: Confocal microscopy is a new technology with clinical applications in ophthalmology. Although confocal microscopy has been used in other fields of medicine, the optical transparency of the cornea and other structures of the eye provides a unique opportunity to apply this technology. The targeted literature review of 24 articles found no level I studies to support the use of confocal microscopy in the management of eye disorders. Three level II studies pertained to promising clinical applications of the confocal microscope and provided evidence that supports the use of confocal microscopy as an adjunctive modality for diagnosing Acanthamoeba keratitis. The remaining 21 articles, rated as level III evidence, focus on the use of confocal microscopy to facilitate the diagnosis of infectious keratitis, including amoebic and fungal, but currently there are no definitive studies of its role in the differential diagnosis of this condition. There are also level III studies that support the use of the confocal microscope in refractive surgery. Facilitating the diagnosis of infectious keratitis and applying the confocal microscope to refractive surgery may hold the greatest promise of this new technology.

Diagnostic Techniques, Ophthalmological↗
PubMed2002

Elevated intraocular pressure-induced interlamellar stromal keratitis.

PURPOSE: To describe a series of cases (Elevated Intraocular Pressure Induced Interlamellar Stromal Keratitis (PISK)) that appears to be identical to post-laser in situ keratomileusis (LASIK) diffuse lamellar keratitis (DLK), but was present at a later time frame and was associated with a significant elevation of intraocular pressure (IOP). Unlike DLK, this syndrome is not steroid responsive, but resolves with a lowering of the IOP. DESIGN: Retrospective, noncomparative, small case series. PARTICIPANTS: The medical records of four LASIK patients with IOP-induced interface changes for the 1-year period March 2000 to March 2001 were reviewed retrospectively. MAIN OUTCOME MEASURE: Slit-lamp appearance. RESULTS: In the four cases presented, the slit-lamp findings and visual degradation appeared identical to DLK. All cases, however, presented outside of the first postoperative week and were not associated with any antecedent trauma. All four cases failed to respond to high-dose topical steroids. Significant IOP elevations were noted in all cases, and the interface changes responded dramatically to both a lowering of the IOP and a discontinuation or lowering of the topical steroids. CONCLUSIONS: Elevated IOP-induced post-LASIK interface keratitis (PISK) is a poorly documented phenomena. Because the condition may be caused by or worsened by frequent topical steroids, early recognition is important. Treatment consists primarily of normalizing the IOP.

Adult↗