Nanohole array as a lens

We demonstrate that a quasi-crystal array of nanoholes in a metal screen can mimic a function of the lens: one-to-one imaging of a point source located a few tens of wavelengths away from the array to a point on the other side of the array. A displacement of the point source leads to a linear displacement of the image point. Complex structures composed of multiple point sources can be faithfully imaged with resolutions comparable to those of high numerical aperture lenses.

Electric currents and lens regeneration in the rat

We studied the process of lens regeneration in the rat following an extracapsular lens extraction preserving the anterior lens capsule and anterior lens epithelium. We assessed clinically the clarity of the newly regenerated lens, evaluated changes in the lens electrical currents following surgery and during the regeneration process and correlated these changes with findings on light microscopy. Protein analysis of the regenerated lens was also undertaken. Experiments were performed in 41 Sprague-Dawley rats, sacrificed at 0, 2, 4 and 8 weeks postoperatively. Our results showed that complete lens regeneration occurred 8 weeks postoperatively only if the anterior epithelium was preserved and the lens capsule was closed surgically. Lens electrical currents, altered following surgery, recovered in parallel with the process of regeneration of the lens. The newly regenerated lens was optically clear and biochemical analysis revealed a pattern of protein expression resembling that observed during lens development. In conclusion, complete lens regeneration occurs in the rat and it is possible that lens electrical signals, together with other cues, may play an important role in this process. © 2009 Elsevier Ltd.

Primary cysts of the iris pigment epithelium. Clinical features and natural course in 234 patients

Objective: To describe the clinical characteristics, natural course, and complications of a large group of patients with primary iris pigment epithelium (IPE) cysts. Design: Observational case series. Participants: Two hundred thirty-four patients with primary IPE cysts participated. Results: Primary IPE cysts were classified as central in 6 patients (3%), midzonal in 50 patients (21%), peripheral in 170 patients (73%), and dislodged in 8 patients (3%). Central (pupillary) IPE cysts were found only in males, peripheral IPE cysts were found most often in females (69%), and no gender predilection was detected for midzonal and dislodged IPE cysts. Central and peripheral IPE cysts occurred in young patients (mean age, 20 and 33 years, respectively), whereas midzonal and dislodged IPE cysts were seen in slightly older patients (mean age, 52 and 45 years, respectively). Central IPE cysts were visible when the pupil was not dilated and appeared most often as a round or collapsed brown lesion arising from the pupillary margin, most commonly superonasally. Midzonal IPE cysts were brown and fusiform, best visualized after pupillary dilation. Peripheral IPE cysts produced a characteristic bulging in the iris stroma near the iris root, but they were directly visible in only 78% of cases. After wide dilation and patient and slit-lamp positioning, they appeared as a round clear lesion behind the iris, most often in the inferotemporal quadrant. Finally, dislodged IPE cysts appeared as a brown oval lesion, free floating in the anterior chamber (12%) or in the vitreous (12%), or fixed in the anterior chamber angle (75%). One hundred twenty-four patients (53%) were followed for a mean of 35 months (range, 3 months-19 years). In these patients, complications associated with IPE cysts included lens subluxation in one case (1%), iritis in one case (1%), focal cataract in two cases (2%), glaucoma in two cases (2%), and corneal touch in five cases (4%). Conclusion: Primary IPE cysts have characteristic clinical features that serve to differentiate them from intraocular malignancies. Most cysts have a benign clinical course, and treatment is rarely necessary.

Clinicopathological correlation of epiretinal membranes and posterior lens opacification following perfluorohexyloctane tamponade

Background/aims - Epiretinal and retrolental proliferation may occur during prolonged use of the novel tamponade agent perfluorohexyloctane (F H ). This study aims to determine whether there is any histological evidence that F H has a role in the formation of these membranes. Methods - Eight epiretinal membranes and three opaque posterior lens capsules were excised from patients in whom F H had been used as a long term retinal tamponade agent. The membranes and capsules were examined employing light microscopic methods, including immunohistochemistry. Results - The epiretinal membranes showed histological features typical of proliferative vitreoretinopathy (PVR) epiretinal membranes, but they also exhibited a dense macrophagic infiltration. In addition, three of the membranes contained multinucleated cells. Macrophages represented up to 30% of the cells present and appeared to contain large intracytoplasmic vacuoles. Similar cells were seen on the back of the posterior lens capsule in one specimen and all three capsules had posterior migration of lens epithelium. Conclusion - The pathological findings are not simply those of PVR. The macrophage infiltration suggests that there may be a biological reaction to F H which could reflect its surmised propensity to emulsify. Further investigations concerning the cellular response to this promising tamponade agent are warranted.

Contact lens use after contact lens-associated infectious ulcers

Purpose: The purpose of this study was to evaluate the outcome of patients with healed moderate to severe contact lens-associated corneal infectious ulcers who were re-fit with contact lenses. Methods: We retrospectively studied patients who were fit with contact lenses on our service and who had had moderate to severe corneal infectious ulcers associated with previous contact lens use. Six patients were included in the study. Results: Gas permeable contact lenses were fit in five patients, and a soft contact lens was fit in one patient. Successful fit was achieved in all cases and visual acuities were equal to or better than 20/30 in all patients. No significant complications were observed after a mean follow-up of 23 months (range, 6-45 months). Conclusion: In this small series of patients with a history of moderate to severe contact-lens related infectious keratitis, no complications were observed after contact lenses were refit. Contact lens wear in patients with a history of infectious keratitis may be safe and useful in order to achieve visual rehabilitation.

Hormone therapy and intraocular pressure in nonglaucomatous eyes

Objective: The influence of sex hormones on intraocular pressure (IOP) has been the focus of recent debate. Previous studies investigating the effects of hormone therapy (HT) on IOP in postmenopausal women have produced conflicting results but have been limited by small numbers of participants. The aim of our study was to compare IOP in women without glaucoma taking HT with those not taking HT. Methods: A prospective cross-sectional study of postmenopausal women visiting a single ophthalmic medical practitioner was conducted. All women with a history of intraocular disease, a family history of glaucoma, or refractive error exceeding ±5 diopters were excluded. Applanation tonometry was used to measure IOP, and participants were then asked if they were current HT users. Results: A total of 263 participants were recruited, of whom 91 reported current use of HT; 172 had never used HT. Within the HT group, 33 were taking an estrogen-therapy and 58 were taking a estrogen-progesterone therapy. Mean IOP in the HT group was significantly lower than that in the non-HT group; the mean difference was 1.41 mm Hg (P <0.001). This difference remained statistically significant after statistical correction for age, use of systemic ß-blockers, and time of IOP measurement. There was no significant difference in mean IOP between women taking combined versus those taking estrogen-only preparations. Conclusions: Our study showed that IOP was significantly lower in women taking HT than in those who had never taken HT, even after removing other possible influences on IOP. The IOP-lowering effect of HT deserves further investigation to explore whether it may represent a possible new therapeutic modality for glaucoma. © 2010 by The North American Menopause Society.

Effects of short term increase of intraocular pressure on optic disc cupping

Aims. To evaluate the effect of acute elevation of intraocular pressure (IOP) on optic disc cupping. Methods. 10 emmetropic and 10 myopic volunteers were included in this study. The cup area (CA) and cup volume (CV) of the optic disc were determined with the Heidelberg retina tomograph (HRT). After baseline determinations, a suction cup was used to increase the intraocular pressure (IOP) to 20-25 mmHg above the baseline and HRT images were obtained. Results. Baseline IOP was 13.5 (SD 1.3) mmHg and 12.6 (2.6) mmHg in the emmetropic and myopic groups, respectively. The IOP was elevated to 35.4 (3.3) mmHg and 34.4 (2.5) mmHg in the emmetropic and myopic groups, respectively. When compared with their baseline values, the cupping variables (CA and CV) were significantly increased (p <0.05) during the suction treatment in both emmetropic and myopic subjects. Conclusion. There was a significant enlargement in the optic disc cupping during the artificial increment of intraocular pressure in both emmetropic and myopic eyes. In non-glaucomatous eyes the optic nerve head has a partially dynamic topography dependent upon the level of IOP.

Recurrent vitreous occlusion of glaucoma drainage device tube in a patient with glaucoma in aphakia:A case report

Patients with spontaneous lens dislocation and glaucoma can be challenging to manage. We present a forty-six year old Caucasian lady who was referred with bilateral high intraocular pressure, and was subsequently diagnosed with glaucoma in association with lens dislocation and Marfan syndrome. Baerveldt glaucoma drainage device tubes were inserted in both eyes due to poor response to medical therapy. However, this was complicated by recurrent vitreous occlusion of both glaucoma drainage tubes requiring further multiple surgical interventions. There have not been any further recurrences of vitreous incarceration or posterior segment complications since, but the patient remains under close follow-up. © 2010 Ang et al; licensee BioMed Central Ltd.

Tono-Pen determination of intraocular pressure in patients with band keratopathy or glued cornea

Aims. To evaluate the intraocular pressure (IOP) measurements in patients with band keratopathy or glued corneas obtained from affected and non-affected areas. Methods. 15 patients with band keratopathy or glued corneas were prospectively recruited. When both eyes were affected, only the right eye was analysed. Tono-Pen readings of IOP were obtained sequentially from the affected and non-affected corneal surface. Additionally, Goldmann applanation tonometry was attempted. Results. Determination of IOP with the Tono-Pen was possible in all cases, while Goldmann tonometry was not performed in three patients because of severe corneal irregularities. The average of the Tono-Pen readings obtained from the affected cornea (34.8 (SD 14.0) mmHg) was consistently and significantly higher (p <0.001) than mean IOP obtained by the Tono-Pen from the non-affected area (14.8 (4.3) mmHg). The average of Goldmann tonometry readings (14.4 (6.1) mmHg) did not differ significantly from the Tono-Pen values obtained from the non-affected corneal area (p = 0.47) but was significantly lower than the Tono-Pen measurements obtained from the affected area (p <0.001) Conclusion. In patients with band keratopathy or glued corneas determination of IOP by Tono-Pen tonometry varies from affected to non-affected area. The Tono-Pen overestimates the level of IOP when it is applied to areas with band keratopathy or with glue.

Effect of sublingual application of cannabinoids on intraocular pressure:A pilot study

PURPOSE: The purpose of this study was to assess the effect on intraocular pressure (IOP) and the safety and tolerability of oromucosal administration of a low dose of delta-9-tetrahydrocannabinol (?-9-THC) and cannabidiol (CBD). PATIENTS AND METHODS: A randomized, double-masked, placebo-controlled, 4 way crossover study was conducted at a single center, using cannabis-based medicinal extract of ?-9-THC and CBD. Six patients with ocular hypertension or early primary open angle glaucoma received a single sublingual dose at 8 AM of 5 mg ?-9-THC, 20 mg CBD, 40 mg CBD, or placebo. Main outcome measure was IOP. Secondary outcomes included visual acuity, vital signs, and psychotropic effects. RESULTS: Two hours after sublingual administration of 5 mg ?-9-THC, the IOP was significantly lower than after placebo (23.5 mm Hg vs. 27.3 mm Hg, P=0.026). The IOP returned to baseline level after the 4-hour IOP measurement. CBD administration did not reduce the IOP at any time. However, the higher dose of CBD (40 mg) produced a transient elevation of IOP at 4 hours after administration, from 23.2 to 25.9 mm Hg (P=0.028). Vital signs and visual acuity were not significantly changed. One patient experienced a transient and mild paniclike reaction after ?-9-THC administration. CONCLUSIONS: A single 5 mg sublingual dose of ?-9-THC reduced the IOP temporarily and was well tolerated by most patients. Sublingual administration of 20 mg CBD did not reduce IOP, whereas 40 mg CBD produced a transient increase IOP rise. Copyright © 2006 by Lippincott Williams & Wilkins.

Control of intraocular pressure after deep sclerectomy

Aim: To study the long-term outcome of deep sclerectomy in patients with open angle glaucoma. Methods: Prospective consecutive series of 43 eyes (38 patients) with medically uncontrolled open-angle glaucoma undergoing deep sclerectomy. All patients underwent clinical assessment before and after surgery at day 7 and at months 1, 3, 6, 12, 18, 24, 36. Surgical success was considered if the patient's intraocular pressure (IOP)>22 mmHg and the IOP was lowered by more than 20% without the use of any medication. Kaplan-Meier survival curves were used to evaluate the success rate. Results: The mean follow-up time was 28.1±8.2 months. Mean IOP decreased significantly from a preoperative value of 24.6±5.5 mmHg to a postoperative value of 18.5±4.6 mmHg at 36 months (P>0.001). Microperforation of TDM occurred in three cases (7.0%) and ciliary body prolapse in one case (2.3%) but did not prevent completion of the operation. Postoperatively, hyphaema was detected in one case and shallow anterior chamber in another case and both were treated conservatively. Bleb encapsulation with elevation of IOP occurred in two cases (4.7%) and was treated with 5-fluorouracil subconjunctival injection. Goniopuncture with neodymium : YAG laser was performed in two cases (4.7%). There were no other late complications with the exception of failure of the operation. On the life-table analysis the success rate at 12, 24, and 30 months were 61.4, 36.6, and 18.9%, respectively. Conclusion: Deep sclerectomy reduced the IOP temporarily while minimising the risk of postoperative complications commonly encountered with standard trabeculectomy. However, after long-term follow-up surgery failed to maintain a low IOP. © 2006 Nature Publishing Group. All rights reserved.