Search PubMed⌕ Search

Biomedical subjects

John D McCann

Publications and source records attributed to John D McCann.

5 recordsLinked to original sources

Treatment of prominent eyes with orbital rim onlay implants: four-year experience.

PURPOSE: Different approaches have been proposed to address the aesthetic or reconstructive challenge associated with relatively prominent eyes. Operations that address the soft tissues alone are prone to failure if the underlying orbital bony relationships are not addressed. Orbital rim advancement can serve as a supplement to orbital decompression in this setting or as an alternative for patients who may not maximally benefit from decompression surgery. METHODS: We report our 4-year experience with porous polyethylene orbital rim onlay grafts used to address relative proptosis in 24 patients. RESULTS: All patients had some degree of subjective and objective improvement. Proptosis decreased an average of 4.65 mm, with a range of 3 to 9 mm, based on single-observer Hertel exophthalmometry measurements (5.2 mm in those with concomitant decompression). Lagophthalmos was also improved in all patients with preoperative inadequacy in eyelid closure. Interpalpebral fissure size was reduced 1.3 mm on average, with a range of 0.5 to 6 mm (2 mm in those with concomitant decompression). Average follow-up was 41 months, with a range of 7 to 70 months. In 3 cases, we noted postoperative lower eyelid retraction with eyelid adhesion to the implant; possible risk factors for this complication included reoperative cases and simultaneous eyelid reconstruction with hard palate grafts. CONCLUSIONS: The porous polyethylene orbital rim onlay implant offers a relatively simple and effective surgical technique for the treatment of symptomatic relative proptosis. It can be used alone or in combination with other techniques including midface lift, lower eyelid retractor recession, and orbital decompression. To be effective, the implant should be placed so that it is flush with or overlapping the orbital rim; lateral displacement negates the effect of the implant in improving the eyelid/globe relationship. Postoperative eyelid retraction with tethering to the implant is a potential risk of the onlay implant, and although it may not be possible to avoid this in all cases, surgeries should be designed to minimize postoperative eyelid retraction.

Anthropometry↗

Use of vinyl polysiloxane impression material to protect and identify the nasolacrimal sac in endonasal dacryocystorhinostomy.

PURPOSE: To determine the role of vinyl polysiloxane impression material (trade name Reprosil) in endonasal dacryocystorhinostomy. METHODS: Case series of 15 consecutive endonasal dacryocystorhinostomies in which vinyl polysiloxane material was used to mark and protect the nasolacrimal sac. Vinyl polysiloxane is mixed from two tubes, then immediately injected in the sac through a preplaced 21-gauge cannula. It is important to be sure the cannula is in the sac to avoid false injection and extravasation. We have found it best to inject a small amount, usually 0.2 to 0.3 mL. RESULTS: A patent osteum was successfully created in 13 of the 15 cases (87%). Complications included two cases of retained vinyl polysiloxane that necessitated removal through an external excision. CONCLUSIONS: Endonasal dacryocystorhinostomy has several advantages compared with the external approach. There is no external scar and the bruising and swelling are substantially reduced, allowing patients to return to work more quickly. In addition, the adjacent nasal anatomy is directly visualized, allowing for simultaneous treatment of any relevant nasal pathology and precise manipulation of the nasal tissues.

Dacryocystorhinostomy↗

Bovine hydroxyapatite orbital implant: a preliminary report.

PURPOSE: To determine the safety and efficacy of bovine hydroxyapatite as an orbital implant material. METHODS: Prospective, consecutive case series of patients undergoing enucleation, evisceration, or secondary orbital implantation. A motility peg was placed in all consenting candidates. Patients were followed 1 week, 1 month, and several months after surgery for signs of inflammation, infection, extrusion, or other complication. RESULTS: Twenty-seven patients received a bovine hydroxyapatite orbital implant. Magnetic resonance imaging was obtained in 3 patients (3 orbits) approximately 4 weeks after surgery and showed signs of peripheral fibrovascular ingrowth in all three cases. Magnetic resonance imaging was obtained in 9 patients (9 orbits) 4 to 12 months after surgery and showed signs of incomplete fibrovascular ingrowth in 1 of 9 (11%) cases, subtotal fibrovascular ingrowth in 2 of 9 (22%) cases, and complete fibrovascular ingrowth in 6 of 9 (67%) of cases. Complications included postoperative chemosis in 3 cases (11%) and exposure requiring reoperation in 2 cases (7%). Motility peg placement was performed successfully in 5 patients (5 orbits). CONCLUSIONS: Bovine hydroxyapatite appears to be a safe and effective orbital implant material. The material appears to be biocompatible and nonallergenic. Bovine hydroxyapatite allows for fibrovascular integration and motility peg placement.

Adolescent↗

Orbital volume augmentation for late enophthalmos using the deep lateral wall.

Orbital volume augmentation to address enophthalmos and hollowing of the superior sulcus has been described with a variety of materials and from a variety of approaches.(1-4) A common location for volume augmentation is the inferomedial orbital wall; this surface is often the one that was expanded related to orbital trauma, and it is easily accessed through hidden conjunctival or caruncular incisions.

Adult↗