Yamamoto Y, Uno T, Shisida K, Xue L, Shiraishi A, Zheng X, Ohashi Y.
Demonstration of aqueous streaming through a laser iridotomy window against the corneal endothelium.
Arch Ophthalmol. 2006 Mar;124(3):387-93. doi: 10.1001/archopht.124.3.387.
Abstract/Text
OBJECTIVE: To determine the pathogenesis of the bullous keratopathy that is frequently observed in patients after argon laser iridotomy (ALI) by comparing the changes in aqueous flow after ALI with those that follow peripheral iridectomy in rabbit eyes.
METHODS: Silicone particles were injected into the anterior chamber of rabbit eyes as tracers to monitor aqueous flow. Particle tracking velocimetry with image analysis was used to determine the direction and speed of aqueous flow in 5 pigmented rabbits that underwent ALI and 5 that underwent peripheral iridectomy.
RESULTS: In the ALI group, silicone particles were found to stream through the iridotomy window against the corneal endothelium immediately after the pupil was constricted by a light stimulus. The mean +/- SD speed of the particles was 2.97 +/- 1.51 mm/s. In contrast, the mean +/- SD flow rate through the iridectomy window in the peripheral iridectomy group was significantly slower at 0.36 +/- 0.30 mm/s (P = .01).
CONCLUSION: Constriction of the pupil elicited marked aqueous streaming through the ALI window against the corneal endothelium. Clinical Relevance The mechanical stress to the corneal endothelium by the abnormal aqueous stream may be partially responsible for the corneal decompensation that follows ALI.
Kaji Y, Oshika T, Usui T, Sakakibara J.
Effect of shear stress on attachment of corneal endothelial cells in association with corneal endothelial cell loss after laser iridotomy.
Cornea. 2005 Nov;24(8 Suppl):S55-S58. doi: 10.1097/01.ico.0000178735.27674.52.
Abstract/Text
PURPOSE: Laser iridotomy often causes bullous keratopathy; however, the mechanism is unclear. We investigated whether changes in aqueous humor hydrodynamics after laser iridotomy have any role in corneal endothelial cell loss.
MATERIALS AND METHODS: Porcine corneal endothelial cells were plated onto glass slides. Following 1 or 3 hours for adhesion, the endothelial cells were exposed to shear stresses (0.1-10 dyne/cm) for 15 minutes, and the number of detached cells was counted. In addition, the pressure and shear stress on corneal endothelial layer were calculated in a virtual model of laser iridotomy.
RESULTS: The number of detached corneal endothelial cells increased with shear stresses in a dose-dependent manner. Significant increase of rate of detached corneal endothelial cells was observed at >0.3 dyne/cm after 1-hour attachment and at 1 dyne/cm after 3-hour attachment. The maximum pressure on corneal endothelial layer was 0.007 mm Hg, which is negligible compared with intraocular pressure. However, the maximum shear stress on the corneal endothelial layer could be> dyne/cm in some conditions of laser iridotomy.
CONCLUSIONS: The resistance of corneal endothelial cell loss to shear stress is time dependent. Shear stress could be a cause of corneal endothelial cell loss in some conditions of laser iridotomy.
Shimazaki J, Amano S, Uno T, Maeda N, Yokoi N; Japan Bullous Keratopathy Study Group.
National survey on bullous keratopathy in Japan.
Cornea. 2007 Apr;26(3):274-8. doi: 10.1097/ICO.0b013e31802c9e19.
Abstract/Text
PURPOSE: To present the results of a national survey on bullous keratopathy (BK) in Japan.
METHODS: A cross-sectional national survey was conducted for 963 eyes with BK seen between 1999 and 2001 by members of the Japan Cornea Society. Demographic characteristics, type of surgery, complications, and postoperative outcome were analyzed.
RESULTS: BK accounted for 24.2% (963 eyes) of total keratoplasties performed during the period. Graft clarity was maintained in 77.4% of cases, and immunologic rejection and elevated intraocular pressure was noted in 10.8% and 15.3%, respectively. Cataract surgery was the most common cause of BK (n = 428, 44.4%), and phacoemulsification and aspiration were performed in approximately 40% of cases. BK secondary to laser iridotomy (LI) was the second most common cause of BK (n = 225, 23.4%). LI was performed as a prophylactic measure in approximately one half of these cases. BK developed with a mean duration of 6.8 years after LI. Fuchs dystrophy was the cause of BK in 18 eyes (1.9%).
CONCLUSIONS: The causes of BK in Japan are considerably different from those in other Western countries. LI-related BKs showed a remarkably high number, whereas Fuchs dystrophy was observed only rarely.
Jacobi PC, Dietlein TS, Lüke C, Engels B, Krieglstein GK.
Primary phacoemulsification and intraocular lens implantation for acute angle-closure glaucoma.
Ophthalmology. 2002 Sep;109(9):1597-603. doi: 10.1016/s0161-6420(02)01123-5.
Abstract/Text
OBJECTIVE: To evaluate the safety and efficacy of primary phacoemulsification and intraocular lens implantation (PPI) for acute angle-closure glaucoma (ACG).
STUDY DESIGN: Prospective, nonrandomized comparative trial.
PARTICIPANTS AND INTERVENTION: Forty-three eyes of 43 patients with acute ACG and uncontrolled intraocular pressure (IOP) were treated by PPI. Thirty-two eyes of 32 patients treated by conventional surgical iridectomy (CSI) constituted the control group.
MAIN OUTCOME MEASURES: Postoperative visual acuity, IOP, number of antiglaucoma medications, complications, and secondary surgical interventions, if any, required for IOP control.
RESULTS: Glaucoma control was achieved in 31 eyes (72%) in the PPI group and in 11 (35%) in the CSI group (P = 0.01). Mean preoperative IOP was 40.5 +/- 7.6 mmHg (standard deviation) and 39.7 +/- 7.8 mmHg, respectively (P = 0.46). Mean postoperative IOP was 17.8 +/- 3.4 mmHg (PPI group) and 20.1 +/- 4.2 mmHg (CSI group) after a mean follow-up of 10.2 +/- 3.4 months (P = 0.03). Postoperatively, the mean number of ocular hypotensive medications was 0.18 +/- 0.45 (PPI group) and 0.45 +/- 0.62 (CSI group) (P = 0.0001). Relative increase in postoperative best-corrected visual acuity (logarithm of the minimum angle of resolution) was 0.52 +/- 0.29 (PPI group) and 0.19 +/- 0.21 (CSI group), respectively (P = 0.0001). Additional surgery was necessary in 5 eyes (11.5%) in the PPI group and in 20 eyes (63%) in the CSI group (P = 0.01). Intraoperative and postoperative complications were few and manageable.
CONCLUSIONS: CSI in patients with acute ACG was effective in reducing IOP initially but was associated with multiple surgical reinterventions. Conversely, primary PPI turned out to be safe and effective in reducing IOP and improving visual acuity. These results affirm that lens extraction may be considered the better procedure in uncontrolled ACG when faced with options of CSI or PPI.
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Results of the Endophthalmitis Vitrectomy Study. A randomized trial of immediate vitrectomy and of intravenous antibiotics for the treatment of postoperative bacterial endophthalmitis. Endophthalmitis Vitrectomy Study Group.
Arch Ophthalmol. 1995 Dec;113(12):1479-96.
Abstract/Text
OBJECTIVE: To determine the roles of immediate pars plana vitrectomy (VIT) and systemic antibiotic treatment in the management of postoperative endophthalmitis.
DESIGN: Investigator-initiated, multicenter, randomized clinical trial.
SETTING: Private and university-based retina-vitreous practices.
PATIENTS: A total of 420 patients who had clinical evidence of endophthalmitis within 6 weeks after cataract surgery or secondary intraocular lens implantation.
INTERVENTIONS: Random assignment according to a 2 x 2 factorial design to treatment with VIT or vitreous tap or biopsy (TAP) and to treatment with or without systemic antibiotics (ceftazidime and amikacin).
MAIN OUTCOME MEASURES: A 9-month evaluation of visual acuity assessed by an Early Treatment Diabetic Retinopathy Study acuity chart and media clarity assessed both clinically and photographically.
RESULTS: There was no difference in final visual acuity or media clarity with or without the use of systemic antibiotics. In patients whose initial visual acuity was hand motions or better, there was no difference in visual outcome whether or not an immediate VIT was performed. However, in the subgroup of patients with initial light perception-only vision, VIT produced a threefold increase in the frequency of achieving 20/40 or better acuity (33% vs 11%), approximately a twofold chance of achieving 20/100 or better acuity (56% vs 30%), and a 50% decrease in the frequency of severe visual loss (20% vs 47%) over TAP. In this group of patients, the difference between VIT and TAP was statistically significant (P < .001, log rank test for cumulative visual acuity scores) over the entire range of vision.
CONCLUSIONS: Omission of systemic antibiotic treatment can reduce toxic effects, costs, and length of hospital stay. Routine immediate VIT is not necessary in patients with better than light perception vision at presentation but is of substantial benefit for those who have light perception-only vision.
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田野保雄, 樋田哲夫編: 今日の眼疾患治療指針第2版. 医学書院, 2007.
本田孔士編:眼痛の診かた. 月刊眼科診療プラクティス72, 文光堂, 2001.
