Four beams evanescent waves interference lithography for patterning of two dimensional features.

This work presents a theoretical study of using the interference of multiple counter-propagating evanescent waves as a lithography technique to print periodic two dimensional features. The formulation of the three dimensional Cartesian space expression of an evanescent wave is presented. In this work, the evanescent wave is generated by the total internal reflection of a plane wave at the interface between a incident dielectric material and a weakly absorbing transmission medium. The influences of polarization, incident angle and the phase shifting of the incident plane waves on the evanescent wave interference are studied. Numerical simulation results suggest that this technique enables fabrication of periodic two dimensional features with resolution less than one third the wavelength of the irradiation source.

To compare argon laser peripheral iridoplasty (ALPI) against systemic medications in treatment of acute primary angle-closure: mid-term results.

PURPOSE: To compare the clinical outcome of argon laser peripheral iridoplasty (ALPI) against systemic medications in treatment of acute primary angle-closure (APAC). METHODS: Consecutive patients with APAC were recruited and randomized to receive one of two treatment options: immediate ALPI or systemic acetazolamide +/- mannitol. All eyes were followed up for at least 6 months after laser iridotomy. Main outcome measures were intraocular pressure (IOP) and requirement for glaucoma medications. RESULTS: A total of 41 eyes (39 patients) were randomized into the ALPI group, and 38 eyes (32 patients) into the medical treatment group. There were no significant differences between the two groups in sex, age, presenting IOP, and duration of attack. Mean follow-up duration +/- SD was 15.7 +/- 5.8 months. There were no significant differences between the two groups in mean final IOP and requirement for glaucoma medications. CONCLUSIONS: There were no statistically significant differences in mean IOP and requirement for glaucoma drugs between APAC eyes treated with ALPI and systemic medications.

Immediate argon laser peripheral iridoplasty (ALPI) as initial treatment for acute phacomorphic angle-closure (phacomorphic glaucoma) before cataract extraction: a preliminary study.

PURPOSE: To study the safety and efficacy of immediate argon laser peripheral iridoplasty (ALPI) as initial treatment of acute phacomorphic angle-closure (phacomorphic glaucoma) before cataract extraction. METHODS: In all, 10 consecutive patients with acute phacomorphic angle-closure and intraocular pressure (IOP) > or =40 mmHg were recruited into the study. Each patient received topical atropine (1%) and timolol (0.5%), and immediate ALPI as initial treatment. The IOP at 15, 30, 60, and 120 min, and then 1 day, after ALPI were documented by applanation tonometry. Systemic IOP-lowering drugs were only started if IOP remained above 40 mmHg at 2 h after ALPI. Cataract extraction was subsequently performed as definitive treatment. RESULTS: In total, 10 patients (five male, five female), with a mean age+/-SD of 73.1+/-10.3 years were recruited. Mean duration of symptomatic attack was 128+/-232 h. After ALPI, the mean IOP was reduced from 56.1+/-12.5 to 45.3+/-14.5 mmHg at 15 min, 37.6+/-7.5 mmHg at 30 min, 34.2+/-9.7 mmHg at 60 min, 25.5+/-8.7 mmHg at 120 min, and 13.6+/-4.2 mmHg at 1 day. In one patient, systemic acetazolamide was administered, because the IOP remained above 40 mmHg at 2 h after ALPI. All 10 patients had uncomplicated cataract extraction performed within 4 days after ALPI. No complications from the laser procedure were encountered. CONCLUSION: Immediate ALPI, replacing systemic antiglaucomatous medications, appeared to be safe and effective as first-line treatment of acute phacomorphic angle-closure.

Effect of intracameral acetylcholine on latanoprost in preventing ocular hypertension after phacoemulsification and intraocular lens implantation.

PURPOSE: To evaluate the effect of intracameral acetylcholine on latanoprost in preventing ocular hypertension in the early period after phacoemulsification with posterior chamber intraocular lens (PC IOL) implantation. SETTING: Department of Ophthalmology and Visual Sciences, Prince of Wales Hospital, Shatin, Hong Kong, China. METHODS: Patients with uncomplicated cataract having phacoemulsification with PC IOL implantation were included in this prospective randomized double-masked clinical trial. The eyes were randomly assigned to 1 of 4 groups based on postoperative application of latanoprost 0.005% alone (Group 1), latanoprost 0.005% with intracameral acetylcholine (Group 2), intracameral acetylcholine alone (Group 3), and no medication (controls (Group 4). Intraocular pressure (IOP) was measured 3 and 24 hours postoperatively. The anterior chamber was examined for the level of cells and flare using slitlamp biomicroscopy. RESULTS: Three and 24 hours after surgery, the decrease in mean IOP in eyes receiving latanoprost alone was not statistically significantly different from that in control eyes (P >.05). Eyes receiving intracameral acetylcholine alone had a significant decrease in the mean IOP at 3 hours (P <.05) but not at 24 hours compared to control eyes (P >.05). There were no significant differences in the mean postoperative IOP decrease between eyes receiving latanoprost with intracameral acetylcholine and those receiving intracameral acetylcholine alone (P >.05). CONCLUSIONS: A single application of latanoprost did not significantly lower IOP in the first 24 hours after phacoemulsification with PC IOL implantation. Eyes receiving intracameral acetylcholine alone had a significantly greater decrease in IOP than control eyes at 3 hours but not at 24 hours. The addition of intracameral acetylcholine to latanoprost did not enhance or reduce latanoprost's IOP-lowering effect.

Immediate diode laser peripheral iridoplasty as treatment of acute attack of primary angle closure glaucoma: a preliminary study.

PURPOSE: To study the efficacy and safety of diode laser peripheral iridoplasty as a first-line treatment of acute primary angle-closure glaucoma (PACG) without the use of systemic anti-glaucoma medications. PATIENTS AND METHODS: Nine consecutive patients with acute PACG were recruited into the study. Each patient received topical pilocarpine (4%), timolol (0.5%), apraclonidine (1%), and immediate diode laser peripheral iridoplasty as primary treatment. The intraocular pressures (IOPs) 15, 30, and 60 minutes after diode laser peripheral iridoplasty were documented by Goldmann applanation tonometry. RESULTS: The mean IOP of this group of patients was reduced from 66.3 +/- 9.7 mm Hg, before diode laser peripheral iridoplasty, to 36.6 +/- 16.4 mm Hg at 15 minutes, 26.3 +/- 12.6 mm Hg at 30 minutes, and 18.9 +/- 8.4 mm Hg at 60 minutes after diode laser peripheral iridoplasty. In seven of the nine patients, the corneal edema cleared up 1 hour after diode laser peripheral iridoplasty. In the remaining patient, the cornea cleared up 12 hours after diode laser peripheral iridoplasty. No significant complications were encountered. CONCLUSION: Diode laser peripheral iridoplasty, together with topical antiglaucoma medications without adjunctive systemic carbonic anhydrase inhibitors and hyperosmotic agents, appeared to be effective and safe in controlling the IOP in acute PACG.

Nevus of Ota: a new classification based on the response to laser treatment.

BACKGROUND AND OBJECTIVE: For 60 years, Tanino's classification has been used to classify the extent of nevus of Ota. However, such classification not only fails to address variants such as phacomatosis pigmentovascularis but also cannot be used to predict the therapeutic outcome. Our objective is to retrospectively study our series of laser-treated patients with the aim of re-classifying nevus of Ota, so that such important issues can be taken into account. STUDY DESIGN/MATERIALS AND METHODS: One hundred nineteen patients that had received Q-switched laser treatment were recruited into the study. They were recalled for interview and examination for evidence of coexisting birthmarks and extracutaneous involvement. Two observers assessed the pre- and posttreatment clinical photographs for evidence of periorbital under-response (panda's sign), defined as the degree of periorbital laser clearing significantly less than clearing in the other area. RESULTS: A total of 47.8% of the patients with periorbital pigmentation were considered by the observers to have significant periorbital under-response (panda's sign). Additionally, 10.1% had other birthmarks, and extracutaneous involvement was seen in 31.4% of the patients. CONCLUSION: Periorbital under-response is commonly seen in patients with periorbital pigmentation. Taking this and other factors into consideration, we have proposed a new classification for nevus of Ota that allows for the prediction of the clinical outcome of laser treatment.

Epidemiological, clinical and laboratory characteristics of 19 serologically confirmed rickettsial disease in Singapore.

AIM: To identify epidemiological, clinical and laboratory features of serologically-proven typhus in the local setting. METHOD & RESULTS: Retrospective study looking at rickettsial serologies done over a six-month period and collection of the epidemological, clinical, laboratory and treatment response data from the case notes of the patients with an ordered rickettsial serology. Twenty of the 35 cases had a positive serology. Of these 20 patients, 18 were already clinically diagnosed as having murine typhus. All except one were males and all were migrant workers. Majority of the patients were construction workers staying in containers where rats abound. The most consistent clinical features were high fever (100%) for a median period of seven days, headache (94%) and cough (47%). The white cell count was usually normal (74%) but thrombocytopenia was common (68%). Transaminitis was also common (90%) with the AST component higher than the ALT in half of the cases. Response to doxycycline therapy was rapid and most (88%) were afebrile by 72 hours. CONCLUSION: Typhus (notably murine type) can be confidently diagnosed from consistent clinical features supported by epidemiological and laboratory clues. Early recognition with the prompt treatment response will result in shorter hospital stay with decreased cost. Serological testing may only prove useful in difficult situations when the clinical diagnosis is less clear.

Absence of trabecular meshwork-inducible stretch response (TISR)/oculomedin gene and proximal promoter mutation in primary open angle glaucoma patients.

We investigated the coding exon and promoter sequence in the trabecular meshwork-inducible stretch response (TISR)/oculomedin gene for mutations in Chinese primary open angle glaucoma (POAG) subjects. The entire TISR/oculomedin coding sequence, together with 138 bp of promoter sequence 5' to the start codon and 170 bp of the 3' untranslated region in 110 Chinese POAG patients and 108 unrelated control subjects without glaucoma, aged 50 years or above, were screened for alterations by DNA sequencing. One heterozygous sequence alteration, K28E, was identified in one control subject, and two homozygous sequence alterations, K28K and 135+36delC, were universally found in every sample. As a result, no common TISR/ oculomedin coding sequence nor any proximal promoter mutation that causes POAG was found. The effect of TISR/ oculomedin in glaucoma has yet to be established.

A retrospective analysis of complications in the treatment of nevus of Ota with the Q-switched alexandrite and Q-switched Nd:YAG lasers.

BACKGROUND: Studies on the use of Q-switched alexandrite (QS alex) and QS Nd:YAG lasers in the treatment of nevus of Ota were limited to case reports and small series. There was no study that looked at the complication rate of these systems. OBJECTIVE: To retrospectively study the complication rate of nevus of Ota patients that were treated with QS alex laser, QS Nd:YAG laser, or a combination of both. METHODS: The study was performed in a teaching hospital and a private hospital, where 513 patients with nevus of Ota had been treated since 1993. The 171 patients with 211 treatment sites were evaluated retrospectively following treatment with QS alex laser only (n = 58), QS Nd:YAG laser (n = 105) only, or a combination of both systems (n = 48). Patients were called back to be interviewed and examined by two independent clinicians to look for evidence of complications. RESULTS: Of the treatment sites, 15. 3% had hypopigmentation, 2.9% had hyperpigmentation, and texture changes and scarring were seen in 2.9% and 1.9%, respectively. The combined treatment group was associated with a significantly higher risk of complications. Thirteen patients had recurrence of their nevus after complete or near-complete clearance with laser treatment. CONCLUSION: Hypopigmentation is common after the use of QS laser for lightening of nevus of Ota. This particularly applies when alternate treatment with QS alex and QS Nd:YAG is used. Recurrence is an important issue and must be taken into consideration, especially when children are treated.

Efficacy and safety of inferior 180 degrees goniosynechialysis followed by diode laser peripheral iridoplasty in the treatment of chronic angle-closure glaucoma.

PURPOSE: To report the efficacy and safety of inferior 180 degrees goniosynechialysis followed by diode laser peripheral iridoplasty in the treatment of chronic angle-closure glaucoma with total synechial angle closure. METHODS: Five patients with chronic angle-closure glaucoma and total synechial angle closure whose intraocular pressures were higher than 21 mm Hg while taking maximally tolerated medications underwent goniosynechialysis followed by diode laser peripheral iridoplasty to the inferior half of the angle. Intraoperative complications, postoperative visual acuity, intraocular pressures, and complications were evaluated. RESULTS: Five eyes of five patients received the operation and the mean follow-up was 7.6 months (range, 6-12 months). The mean preoperative intraocular pressure was 33.8 +/- 5.8 mm Hg. The mean postoperative intraocular pressure at most recent follow-up was 15.8 +/- 2.2 mm Hg. Postoperative complications included transient increase in intraocular pressure, hyphema, and cataract. The success rate (intraocular pressure less than 20 mm Hg with or without medication) was 80.0%. CONCLUSION: It appears that 180 degrees goniosynechialysis followed by diode laser peripheral iridoplasty is an effective and safe surgical procedure for treating chronic angle-closure glaucoma with total synechial angle closure.

The association between cigarette smoking and ocular diseases.

OBJECTIVE: To review the effect of smoking on common ocular disorders. DATA SOURCES: Medline literature search, 1966 to 1999. STUDY SELECTION: The following key words were used: smoking; Graves' disease, age-related macular degeneration; glaucoma; cataract. DATA EXTRACTION: Epidemiological and experimental studies were reviewed. DATA SYNTHESIS: Cigarette smoking is an important risk factor for cardiovascular, respiratory, and malignant diseases. There is also a strong association between smoking and a number of common eye diseases, which include Graves' ophthalmopathy, age-related macular degeneration, glaucoma, and cataract. Despite the multifactorial aetiology of these ocular syndromes, smoking is an independent risk factor that has dose-response effects. It causes morphological and functional changes to the lens and retina due to its atherosclerotic and thrombotic effects on the ocular capillaries. Smoking also enhances the generation of free radicals and decreases the levels of antioxidants in the blood circulation, aqueous humour, and ocular tissue. Thus, the eyes are more at risk of having free-radical and oxidation attacks in smokers. CONCLUSION: Smoking, if continued, may perpetuate further ocular damage and lead to permanent blindness. Cessation of smoking and avoidance of passive smoking is advised to minimise the harmful effects of smoking on the eyes.

Efficacy and safety of the Ahmed glaucoma valve implant in Chinese eyes with complicated glaucoma.

AIMS: To evaluate the efficacy and safety of the Ahmed glaucoma valve implant in Chinese eyes with complicated glaucomas. METHODS: This retrospective study reviewed the final intraocular pressure, visual outcome, and incidence of complications in all patients with the Ahmed glaucoma valve implant performed at the Prince of Wales Hospital, Hong Kong, between June 1996 and November 1998. RESULTS: A total of 65 eyes from 60 patients were treated with the Ahmed glaucoma implant. At a mean follow up (SD, median) of 21.8 (9.2, 28. 0) months (range 6-37 months), the mean intraocular pressure was reduced from 37.0 (SD 12.1) mm Hg before the implant surgery to 16.1 (12.4) mm Hg at the last follow up after surgery. The success rate of intraocular pressure control of <22 mm Hg was achieved in 73.8% of operated eyes. Transient postoperative hypotony with shallow anterior chamber occurred in 10.8% of cases. The most common postoperative complication was the formation of encapsulated bleb (24.6%). CONCLUSIONS: The Ahmed glaucoma valve implant appears to be effective and relatively safe for treating complicated glaucomas in Chinese eyes. The success rate is comparable with those reported in non-Asian eyes. Formation of postoperative encapsulated bleb is, however, more commonly encountered.

Truncations in the TIGR gene in individuals with and without primary open-angle glaucoma.

PURPOSE: To investigate the coding exons in the trabecular meshwork-induced glucocorticoid response protein (TIGR) gene for mutations in primary open-angle glaucoma (POAG) in Chinese subjects. METHODS: Ninety-one Chinese patients with POAG and 113 of their family members without glaucoma were screened for sequence alterations in the TIGR gene by polymerase chain reaction, conformation-sensitive gel electrophoresis, and DNA sequencing. One hundred thirty-two unrelated individuals without glaucoma, aged 50 years or more, were studied as control subjects. RESULTS: Five sequence variants that lead to amino acid changes were identified. One was novel: Arg91Stop in one patient with POAG. Four had been reported: Arg46Stop in subjects with and without POAG, including an unaffected 77-year-old woman homozygous for Arg46Stop; Gly12Arg in subjects without glaucoma; and Asp208Glu and Thr353Ile in subjects with and without POAG. The previously reported 1-83(G-->A) and Arg76Lys polymorphisms were detected in both patients and controls and always occurred together. CONCLUSIONS: A different pattern of TIGR sequence variants exists in the Chinese than in non-Chinese populations. No common TIGR mutation that causes POAG was found. The occurrence of subjects without glaucoma who are heterozygous or homozygous for Arg46Stop suggests that reduction in the amount of TIGR protein does not cause glaucoma. Thus, the TIGR missense mutations known to cause POAG probably do not cause glaucoma by inactivating a normal TIGR function, but rather through the gain of a pathologic function.

Latanoprost versus timolol gel to prevent ocular hypertension after phacoemulsification and intraocular lens implantation.

PURPOSE: To evaluate the efficacy of latanoprost and timolol gel in preventing ocular hypertension in the early period after phacoemulsification and posterior chamber intraocular lens (PC IOL) implantation. SETTING: Department of Ophthalmology and Visual Sciences, Prince of Wales Hospital, Hong Kong, China. METHODS: This prospective randomized double-masked clinical trial comprised patients with uncomplicated cataract having phacoemulsification with PC IOL implantation. They were randomly assigned to 1 of 3 groups: postoperative application of timolol 0.5% gel-forming solution (Timoptol-XE(R)) (Group 1), latanoprost 0.005% (Group 2), and control (Group 3). Intraocular pressure (IOP) was measured 2, 4, and 24 hours postoperatively. The anterior chamber was examined for the levels of cells and flare using slitlamp biomicroscopy. RESULTS: Group 1 had a significantly greater reduction in mean IOP 2, 4, and 24 hours after phacoemulsification and PC IOL implantation than Group 3 (P <.05). There were no significant differences between Groups 2 and 3 at any interval (P. 05). No excessive postoperative anterior chamber inflammation was observed in any group. CONCLUSIONS: A single dose of latanoprost given after phacoemulsification and PC IOL implantation did not produce a significant IOP-lowering effect when compared with a control group in the first 24 hours postoperatively. A single dose of timolol gel produced a significant postoperative IOP decrease as soon as 2 hours and up to 24 hours after surgery. Timolol gel and latanoprost are safe, but timolol is more effective than latanoprost in preventing postoperative ocular hypertension.