Biomedical subjects

Hiroyuki Nakashizuka

Publications and source records attributed to Hiroyuki Nakashizuka.

6 recordsLinked to original sources

PubMed2006

Thermal injury caused by chandelier fiber probe.

PURPOSE: To investigate thermal changes produced by a chandelier fiber probe (CFP). DESIGN: Interventional single case report and laboratory investigation. METHODS: When CFP was used for 25-gauge vitrectomy, an abnormal odor was emitted, and the CFP was instantly removed. To investigate this incident, the thermal change produced by the CFP was measured in air by means of an infrared sensor. Porcine Tenon capsular tissue was used to reproduce the intraoperative phenomenon. RESULTS: In our patient, the CFP tip melted, but this did not affect visual function. In the experiment, the uncoated CFP reached 49 C (120 F) at maximum illumination. When porcine Tenon capsular tissue was attached to the CFP tip, a temperature of 144 C (291 F) was reached at 50% of maximum illumination, and over 201 C (394 F) at 75%. The tip melted under these conditions. CONCLUSIONS: At present, we avoid the use of CFP during air exchange. This potential hazard of the CFP needs to be addressed.

Body Temperature↗

PubMed2006

25-gauge scleral tunnel transconjunctival vitrectomy.

PURPOSE: To compare the intraocular fluid leakage rate between 25-gauge (25G) transconjunctival vitrectomy with scleral tunnels and standard 25G transconjunctival vitrectomy. DESIGN: Single-center, retrospective, interventional case series. METHODS: Transconjunctival vitrectomies were conducted by the use of only 25G instruments with peripheral vitrectomy. Standard 25G vitrectomy was conducted in 542 eyes and 25G vitrectomy with scleral tunnels in 337 eyes. The scleral tunnel was created by inserting trocars at an oblique angle. RESULTS: The intraocular fluid leakage rate was significantly lower (Fisher exact probability test: P < .0001) when scleral tunnels were used in 25G vitrectomy (1%, five of 337 eyes) compared with standard 25G vitrectomy (9%, 50 of 542 eyes). The wound leakage rate was significantly lower when using (rather than not) scleral tunnels in 25G vitrectomy, both without air-gas (P = .0258) and with air exchange (P = .0007). CONCLUSION: The use of scleral tunnels in 25G transconjunctival vitrectomy reduces the frequency of wound leakage even when the peripheral vitreous is removed.

Adolescent↗

PubMed2004

Pars plana suture fixation for intraocular lenses dislocated into the vitreous cavity using a closed-eye cow-hitch technique.

We describe a modified intraocular cow-hitch technique for pars plana suture fixation of intraocular lenses (IOLs) that dislocated into the vitreous cavity in 3 patients who had a 3-port vitrectomy and IOL implantation because of retinal disease. To reposition the dislocated IOL after the residual vitreous was removed, 2 additional sclerotomies for suture fixation were made 3.0 mm posterior to the limbus. A loop (cow-hitch knot) was made with 10-0 polypropylene for suture fixation. After the neck of the cow-hitch loop was grasped with an intraocular forceps, the loop was used to lasso a haptic of the dislocated IOL, which was then pulled forward to the sclerotomy. The same procedure was used for the other haptic, and both sutures were secured to the sclera under scleral flaps. In all patients, the dislocated IOLs were repositioned without the need for extraction. The procedures were uneventful. Pars plana suture fixation with the intraocular cow-hitch technique can be used to reposition an IOL that has dislocated into the vitreous cavity.

Adult↗

PubMedDate not supplied

Twenty-gauge Transconjunctival Vitrectomy.

PURPOSE: To describe a new 20-gauge transconjunctival vitrectomy procedure that we designed, to evaluate its usefulness, and to compare two different methods of use. METHODS: The records of 431 patients (433 eyes) who underwent 20-gauge transconjunctival vitrectomy at the Surugadai Hospital of Nihon University between March 2003 and January 2004 were studied retrospectively. In surgical method 1, 20-gauge wounds were made through the conjunctiva and sclera together. In surgical method 2, 20-gauge conjunctival openings were made 2 mm posterior to the sclerotomies. Absorbable sutures were used to stitch the scleral and conjunctival openings simultaneously in both methods. RESULTS: A 20-gauge transconjunctival vitrectomy has various benefits and is indicated for nearly all ocular diseases. Moreover, it is not limited by the intraocular instruments required. However, since cannulas were not placed in all ports, conjunctival edema occurred more easily with surgical method 2 owing to the leakage of perfusion fluid. CONCLUSIONS: This new 20-gauge transconjunctival vitrectomy procedure has various benefits and is indicated for nearly all ocular diseases. It is not limited by the intraocular instruments required.

Adult↗

PubMedDate not supplied

Expanded indications for 25-gauge transconjunctival vitrectomy.

PURPOSE: We conducted 25-gauge (25G) transconjunctival vitrectomy to treat patients with various ocular diseases, and examined the possibility of expanding the indications for this system through combined use with 20G devices when needed. METHODS: The records of 167 patients (169 eyes) who underwent vitrectomy in our hospital between April and June 2004 were studied. Vitrectomy had been conducted using the 20G or 25G transconjunctival vitrectomy system. RESULTS: In 7 of the 169 eyes (4%), the 20G system was initially selected. Vitrectomy could be performed using the 25G system alone in 150 eyes (89%), while 20G devices were used in combination with the 25G system in 12 (7%). None of the 25G scleral wounds were sutured, while all the 20G scleral wounds were sutured at the completion of surgery. Low intraocular tension was noted in 15 of 162 eyes (9%), but all these eyes recovered within 2 to 4 days. In two eyes with macular hole, retinal detachment occurred, but reattachment was achieved after reoperation. No extensive vitreoretinal hemorrhage or postoperative infection was observed. CONCLUSIONS: By combining the use of 20G devices, indications for the 25G system can be expanded. However, postoperative low ocular tension must be addressed by carefully considering surgical indications and prevention measures.

Adolescent↗

PubMedDate not supplied

Varicella-zoster viral antigen identified in iridocyclitis patient.

BACKGROUND: The varicella-zoster virus (VZV) antigen has not been identified immunohistologically in iridocyclitis due to VZV. CASE: A 65-year-old woman diagnosed with iridocyclitis and secondary glaucoma underwent trabeculectomy. Samples of aqueous humor and juxtacanalicular and iris tissue were obtained for immunohistological and polymerase chain reaction (PCR) study. OBSERVATIONS: Slit-lamp microscopy revealed ciliary injection, corneal epithelial edema, mutton fat precipitates, flare, cells, and progressive iris atrophy in the right eye. Subsequently, scant eruptions on her right upper eyelid appeared and disappeared within a week. Although a diagnostic increase in the complement fixation antibody titer to VZV was not observed, we started medical treatment for VZV, on suspicion of iridocyclitis due to VZV. Despite medical treatment, the ratio of peripheral anterior synechia was greater than 60% and iris atrophy progressed in parallel. The intraocular pressure in the right eye remained above 30 mm Hg at 6 months after the first visit, so trabeculectomy was performed. VZV-specific DNA was detected in the aqueous humor by the PCR study. Immunohistological examination demonstrated numerous VZV antigen-positive cells in the iris stroma, in particular, vascular endothelial cells. CONCLUSION: To our knowledge, this is the first report of the detection of VZV antigen in the iris of an iridocyclitis patient.

Aged↗