Visual fields during acute exposure to a simulated altitude of 7620 m.

BACKGROUND: The hypoxia associated with sudden exposure to high altitude is known to impair vision and may thereby affect flight safety. However, no data were available regarding hypoxic effects on visual fields. The aim of this study was to evaluate black-and-white visual field sensitivity with acute hypoxia during acute exposure to a simulated altitude of 7620 m. METHODS: Subjects were 15 male pilots 26-39 yr of age. We measured arterial oxygen saturation (S(aO2)%) using transdermal pulse oximetry while the visual field was measured within a 30 degrees eccentricity in the right eye by computerized perimetry. The subject breathed 100% O2 for 30 min before and during chamber ascent, then removed his mask while measurements were performed. RESULTS: The S(aO2)% and visual field sensitivities (mean +/- SD) at ground level were 99.1 +/- 0.4% and 43.9 +/- 2.1 dB, respectively. During hypoxia, the S(aO2)% dropped to 64.0 +/- 5.4% within 3 min. Mean visual sensitivity was significantly reduced by 7.2 +/- 1.6 dB. Furthermore, peripheral sensitivity was slightly but significantly more diminished than central sensitivity. CONCLUSIONS: Severe acute hypoxia reduces central and moderate peripheral black-and-white vision by a factor of two with the strongest effect in the periphery.

Long-term corneal retention of trichomes from bamboo shoots.

PURPOSE: To describe a rare case of corneal injury by trichomes of bamboo shoots. METHODS: A 58-year-old woman rubbed her right eye after touching a bamboo shoot, not knowing that there were many trichomes adherent to her hands. Severe conjunctival congestion and chemosis developed immediately but subsided the next day without visual impairment. Many trichomes were incidentally found to be embedded in the subepithelial region of the cornea on a routine slit-lamp examination. Three days after partial removal of the trichomes under a microscope, the epithelium had healed completely. RESULTS: Histopathologic examination showed bamboo trichomes in the epithelial scraping without inflammation. CONCLUSIONS: Trichomes of bamboo shoots may affect and stay in the cornea without significant inflammation because of their inert nature.

Acute corneal hydrops with perforation after LASIK-associated keratectasia.

Herein a case of acute corneal hydrops with perforation in keratectasia 9 years after bilateral laser in situ keratomileusis is presented. A 27-year-old man presented with right eye sudden loss of vision. Right eye best-corrected visual acuity was counting fingers. Left eye best-corrected visual acuity was 6/9. Right eye slit-lamp examination revealed diffuse corneal oedema with central epithelial cystic change. The interface between the flap and residual stroma was open and filled with fluid. This separation extended nearly to the flap margin. Shallow anterior chamber and aqueous leakage were noted the following day. An emergency penetrating keratoplasty was performed to the right eye. Histopathology of corneal button revealed reactive keratocytes with irregular, wrinkled collagen formation over ablated stroma. Marked stromal oedema was observed. Twelve months after corneal transplantation, vision improved to 6/6 with correction in the right eye.

Clinical outcomes of combined sutureless vitrectomy with triamcinolone stain to manage vitreous loss resulting from posterior capsule rupture during phacoemulsification.

PURPOSE: To investigate the efficacy of sutureless pars plana vitrectomy (PPV) combined with intracameral triamcinolone stain in the management of vitreous loss associated with phacoemulsification. SETTING: Department of Ophthalmology, Tri-Service General Hospital, Taipei, Taiwan, Republic of China. METHODS: This retrospective review comprised the charts of 21 patients who had sutureless PPV combined with intracameral triamcinolone stain to manage vitreous loss resulting from posterior capsule rupture during phacoemulsification. The charts were analyzed for type of cataract, posterior segment pathology, methods of anesthesia, intraocular lens (IOL) placement, postoperative visual acuity, intraocular pressure, and complications. Additional outcome measurements were duration of the surgical procedures, period of postoperative corneal edema, and time to achieve stable vision. RESULTS: Excluding 2 eyes with preexisting conditions, 18 of 19 eyes (94.7%) had a final best corrected visual acuity (BCVA) of 20/40 or better and 42.1% (8/19) had a final BCVA of 20/20 or better. The mean duration of the surgery was 25.3 minutes (range 16 to 40 minutes). Corneal edema was noted in 12 eyes (57.1%) 3 days postoperatively and 3 eyes (14.3%) at 7 days. Eleven eyes (52.4%) had stable vision at 1 week, and 16 eyes (76.2%) had stable vision within 1 month postoperatively. Four eyes (19.0%) had postoperative complications that included a displaced IOL in 3 eyes (14.3%) and cystoid macular edema in 1 eye (4.8%). CONCLUSIONS: Self-sealing, sutureless PPV combined with intracameral triamcinolone stain was a safe, reliable adjunct to manage vitreous loss during phacoemulsification. The surgery led to rapid visual recovery.

Comparison of clear corneal phacoemulsification combined with 25-gauge transconjunctival sutureless vitrectomy and standard 20-gauge vitrectomy for patients with cataract and vitreoretinal diseases.

PURPOSE: To compare effectiveness and outcomes of clear corneal phacoemulsification combined with 25-gauge transconjunctival sutureless vitrectomy and standard 20-gauge vitrectomy system for patients with clinically significant cataract and vitreoretinal diseases. SETTING: Department of Ophthalmology, Tri-Service General Hospital, Taipei, Taiwan, Republic of China. METHODS: Clear corneal phacoemulsification combined with 25-gauge transconjunctival sutureless vitrectomy was performed in the study group (15 eyes). Patients in the control group (15 eyes) had combined surgery with clear corneal phacoemulsification and the existing 20-gauge vitrectomy system, providing a comparison between 2 groups with regard to preoperative and postoperative best corrected visual acuity (BCVA), intraocular pressure, and intraoperative and postoperative complications. The additional outcome measurements in both groups were duration of the surgical procedures, time to return to preoperative corneal clarity, time to achieve stable vision, and subjective ocular irritation postoperatively. RESULTS: Postoperatively, BCVA improved in 12 eyes (80%) in the study group and in 11 eyes (73.3%) in the control group. Mean operative time for opening and closing the sclerotomy was significantly greater in the control group than in the study group. Time to return to preoperative corneal clarity and time to achieve stable vision showed no significant difference between the groups. Compared with the control group, postoperative ocular irritation in patients in the study group was considerably reduced. CONCLUSIONS: Combined sutureless surgery needed shorter setup time for sclerotomy and caused less postoperative ocular irritation than combined surgery with 20-gauge vitrectomy. Therefore, this type of procedure would be a good option for selected cases with cataract and vitreoretinal diseases.

Minocycline partially inhibits caspase-3 activation and photoreceptor degeneration after photic injury.

PURPOSE: To evaluate the possible role of caspase-3 in retinal photic injury, and to investigate whether minocycline can ameliorate light-induced photoreceptor degeneration. METHODS: Retinal photic injury was induced in rats by exposure to intense light. Expression of caspase-3 was studied using Western blot analysis, immunohistochemical staining and enzyme activity assay. Apoptotic photoreceptor cells were detected by the TdT-dUTP terminal nick-end labeling (TUNEL) method. Minocycline (15, 30 or 45 mg/kg) was administered before or after photic injury in rats randomly assigned to pretreatment and posttreatment groups. Minocycline and vehicle-treated retinas subjected to photic injury were compared with respect to Western blotting, enzyme activity assay, quantitative counts of TUNEL stains, morphometry of the outer nuclear layer (ONL) thickness and histopathological examination. RESULTS: After light exposure, active caspase-3 and poly-adenosine diphosphate-ribose-polymerase were upregulated in the retinas and increased caspase-3 immunoreactivity was observed in the ONL. Caspase-3 enzyme activity increased in the retinas that underwent photic injury, and this increase was significantly reduced in minocycline pretreated (30 and 45 mg/kg) and posttreated (45 mg/kg) groups. Intraperitoneal administration of minocycline before or after photic injury in rats also resulted in less TUNEL-positive photoreceptors, as assessed by the quantitative TUNEL counts. The degree of retinal degeneration, measured by the ONL thickness 14 days after photic injury, was significantly improved in minocycline pretreatment (45 mg/kg) rats. CONCLUSIONS: We demonstrate that increased caspase-3 activities localize specifically within the ONL after photic injury, and that minocycline partially inhibits caspase-3 activation and photoreceptor degeneration in this animal model.

Comparison of higher-order wavefront aberrations with 3 aberrometers.

PURPOSE: To evaluate the agreement of higher-order aberrations (HOAs) between aberrometers based on the Hartmann-Shack wavefront technology. SETTING: Department of Ophthalmology, Tri-Service General Hospital, Taipei, Taiwan. METHODS: Three clinical aberrometers WaveScan (Visx Inc.), LADARWave (Alcon Inc.), and Zywave (Bausch & Lomb Inc.) were used to measure HOAs in 34 cycloplegic eyes in 17 subjects. All the measurements in each subject were performed in 1 visit to reduce the impact of biologic fluctuation of HOAs. Each device was operated by an independent experienced operator, and the operators were blind to the data obtained from the other aberrometers. Root mean square (RMS) of coma, spherical aberration, and total 3rd- and 4th-order HOAs were compared between any 2 devices by a paired t test. RESULTS: WaveScan had the lowest mean RMS, whereas Zywave reported the highest mean RMS for any HOAs. The coefficients of variation were similar between any 2 devices. Paired t tests of RMS yielded a P value <.01 in 9 of 12 comparisons. In general, the largest discrepancies of HOA measures were between WaveScan and Zywave, and similar data were found between LADARWave and WaveScan. More than 80% of the absolute difference of HOA RMS between LADARWave and WaveScan, 50% to 78% between LADARWave and Zywave, and 38% to 59% between WaveScan and Zywave were within +/-0.1 microm. CONCLUSIONS: Significant discrepancies in HOA measurements were found among the 3 popular aberrometers. The HOA RMS data were closer between LADARWave and WaveScan, and HOA RMS by Zywave was generally higher than the other 2 devices. The 3 devices had comparable measurement variation.

The experience with Ritleng intubation system in patients with congenital nasolacrimal duct obstruction.

BACKGROUND: To report the clinical experience and success rate with Ritleng intubation system in patients with congenital nasolacrimal duct obstruction. METHODS: Twenty-four patients (32 eyes) with congenital nasolacrimal duct obstruction treated with the Ritleng intubation system were enrolled in this study. The mean age was 20.1+/-9.6 months. The technique involved introduction of a Prolene monofilament guide thread, securely fastened to silicone tubing, into a tubular metal probe that opened into the inferior meatus. Success was defined as complete resolution of previous symptoms and a normal result of dye disappearance test in cooperative patients. To establish relationship of success rate with patients' ages, these data were compared and analyzed. RESULTS: All eyes were successfully intubated with the Ritleng system. The Prolene monofilament spontaneously emerged from the nose in 19 (60%) of 32 eyes, making retrieval simple and uncomplicated. The overall success rate (of all aged groups) was 90%. In the group over 24 months of age, there was no significant decrease in the success rate (p > 0.1), but obvious difficulty in intubation and lengthy operation time were noted. CONCLUSIONS: Silicone intubation with the Ritleng system is an effective treatment for patients with congenital nasolacrimal duct obstruction, especially at young age. Comparing with conventional metal probe system, there was minimal nasal bleeding and trauma to the nasal mucosa with Ritleng intubation system. With the advantage of easy retrieval, operation time can be shortened, thereby improving patient care and decreasing potential morbidity.

Calcified cataractous lens.

We report a calcified cataractous lens in a 24-year-old man who had retinal degeneration in the right eye since childhood. The visual acuity had dropped to light perception. Clear corneal phacoemulsification was performed, and the shell of a 5.4 mm x 4.0 mm x 2.0 mm calcified substance was removed with a forceps using the can-opener technique. The specimen was analyzed using radiological study, histopathological examination, chemical element analysis, and transmission electron microscopy. Four years postoperatively, the patient's visual acuity was 20/200.