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Oxygen delivery to the anterior chamber of the eye--a novel function of the anterior iris surface.

By means of pO2-needle electrodes the oxygen tension in the anterior chamber of rabbit and cynomolgus monkey eyes was measured and correlated with the topography. It can be clearly shown that the pO2 in front of the pupil is substantially lower than in front of the anterior iris surface. It is evident that the O2-supply of the anterior chamber is provided by the iris vasculature. This result was confirmed by measurements after partial or total iridectomy. A brief recapitulation of the morphology of the iris showed that the abundance of iris vasculature is well understandable in view of these pO2 measurements.

Animals↗

Autosomal dominant congenital miosis with megalocornea.

A family with AD congenital miosis is presented. The ocular symptoms were: megalocornea, iris translucency, microcoria with poor pupillary dilatation and goniodysgenesis with anterior insertion of the iris. This observation confirms that in congenital miosis abnormal development of the whole anterior eye segment may occur. The patients have an increased risk to develop glaucoma. If retinoscopy is impossible due to pin-point pupils, ultrasonic biometry to determine the axial length is recommended. An optical iridectomy could improve visual performance at low illumination; the complaints of photophobia, which are related to the iris translucency, persist.

Adolescent↗

Comparison of delayed-onset glaucoma and early-onset glaucoma after infantile cataract surgery.

PURPOSE: To investigate the causes and characteristics of glaucoma in children following cataract surgery. METHODS: Twenty-four patients (37 eyes) with uncomplicated congenital cataracts who developed glaucoma after cataract surgery were studied retrospectively. Variables included cataract morphology, surgical techniques, post-operative complications, time to the onset of glaucoma, gonioscopic findings, presence of microcornea and the histopathologic characteristics of the filtration angle (in one case). RESULTS: There was a bimodal onset of glaucoma after cataract surgery. Early-onset glaucoma occurred at a mean age of 6 months in 15 eyes and delayed-onset glaucoma at a mean age of 12 years in 22 eyes. Early-onset glaucoma was significantly (p = 0.018) more likely to be due to angle closure than delayed-onset glaucoma. With delayed-onset glaucoma, the filtration angle was open in 86% of eyes and significantly (p = 0.006) more eyes in the delayed-onset group had microcornea. Medical treatment was sufficient to control intraocular pressure in the delayed-onset group while the early-onset group required surgical treatment (P < 0.001). CONCLUSIONS: The onset of glaucoma after cataract surgery during infancy follows a bimodal pattern that is correlated with the configuration of the filtration angle. The early-onset glaucoma group had high incidence of angle closure requiring surgical treatment, while in the delayed-onset group non-surgical treatment was sufficient to control intraocular pressure. Prophylactic iridectomy in eyes at risk for pupillary block is recommended. Eyes with delayed-onset glaucoma have open filtration angles yet also have findings of incomplete development of filtration structures. Microcornea is a risk factor for delayed-onset glaucoma.

Adolescent↗

Strategy for decentralised prevention of angle closure glaucoma in Greenland.

In 1962 a blindness survey showed glaucomas to be responsible for 64% of all blindness in Greenland. In 1968 primary angle closure glaucoma was found to be the major glaucoma problem. Population studies using gonioscopy, optical anterior chamber depth, corneal thickness, diameter- and curvature measurements as well as ultrasound biometry were gradually performed. Prevalence was estimated at 5.1% in women and 1.6% in men aged 40+. Main findings were eye traits associated with increased risk of angle closure glaucoma: shallow anterior chamber depth and small corneal diameters. A high heritability (70%) was found. Surgical iridectomies and later YAG-laser iridotomies were introduced as routine procedures by travelling consultants and at the referral centre Rigshospitalet in Copenhagen. Eventually, in 1993-96 a surgical eye clinic was established in the capital Nuuk, also introducing phakoemulsification cataract surgery. Blindness due to glaucomas had fallen to about 9% of the registrations in Greenland per 1999. In 1999 an outreach model had to be established again, including consultants covering the 16 districts in 45 weeks and surgical teams of 2 surgeons 3 x 3 weeks per year. In 2002 the coverage was reduced to 31 weeks and only two surgical tours.--The possible consequences for glaucoma blindness will be discussed.

Glaucoma, Angle-Closure↗

Gonioscopic findings in trabeculectomies in young children.

To discover why trabeculectomy often fails in children, we studied a series of 27 procedures, focusing on intraocular and scleral factors that prevent humoral drainage. Gonioscopy was performed under anesthesia with Fluothan (ICI, UK), and trabeculectomy was considered successful when values were equal to or lower than 20 mm Hg. Only ten procedures proved successful, and all had large basal iridectomies plus visible anterior scleral openings at gonioscopy. Possible causes for the 17 failures are listed, together with indications for revision surgery.

Child↗

Neodymium:YAG pupilloplasty in pediatric aphakia.

An adequate pupillary aperture is required for accurate ophthalmoscopy and retinoscopy in pediatric aphakia. When pupillary miosis does not respond to pharmacologic dilation, optical iridectomy performed with a vitreous suction-cutting instrument under general anesthesia may be required. We report a 27-month-old aphakic child whose pupillary aperture was enlarged from 1 mm to 3.5 mm with neodymium (Nd):YAG pupilloplasty, following intramuscular sedation with meperidine, promethazine, and chlorpromazine. Removal of the laser chin rest and positioning of the patient on a table with adjustable height facilitated delivery of 140 applications at 2.5 to 4.3 mJ to the pupillary border. Levobunolol 0.5% controlled the transient posttreatment rise in intraocular pressure. We suggest that Nd:YAG pupilloplasty performed with sedation be considered as an alternative to intraocular surgery when pupillary miosis in pediatric aphakia does not respond to dilating agents.

Aphakia↗

Cataract surgery in children with uveitis.

PURPOSE: To report the technique and postoperative results of cataract surgery in children with uveitis. METHOD: Between 1988 and 1998, nine children (age range: 2.5-11 years) who developed secondary uveitic cataract and underwent cataract extraction were studied retrospectively. Seven children had juvenile rheumatoid arthritis and two had chronic anterior uveitis of unknown etiology. The surgical technique was lensectomy and wide anterior vitrectomy with limbal approach, lysis of anterior synechiae and in some cases, peripheral iridectomy. Postoperative aphakia was corrected with soft contact lenses in all patients. Follow-up ranged from 6 months to 6 years. RESULTS: Postoperatively, visual acuity in all patients improved and final visual acuity ranged from 20/70 to 20/25. Significant intraoperative complications did not occcur in any patient. One boy with juvenile rheumatoid arthritis developed cystoid macular edema 1 month postoperatively, which was successfully managed. He also developed hypertonia 1 year later, which was also successfully managed. Seven of the nine children had fewer and milder relapses of uveitis after surgery. CONCLUSION: Cataract surgery, using the lensectomy-vitrectomy technique in children with uveitis, is a safe technique with a relatively small percentage of postoperative complications and good functional results.

Aphakia, Postcataract↗

Surgical treatment of keratoconus at the turn of the 20th century.

PURPOSE: This paper reviews surgical modalities for treatment of keratoconus at the threshold of the 20th century. METHODS: All ophthalmic literature from 1895 until 1925 in English and German, available at the library of the Institute of Ophthalmology, London, United Kingdom, was studied with respect to this topic. RESULTS: Three thermal procedures were described; galvanocauterization with perforation, without perforation, and a non-contact application of heat to the corneal apex. Radial extension of a thermal burn to correct the minus cylinder represented a further modification. Excision of the conical area was suggested either as a lamellar dissection or as a full thickness trephination. Incision of the cone appeared to be less popular. In staged procedures, a combination of galvanocauterization, splitting of the cornea, conjunctival flap, and a subsequent optical iridectomy were applied. CONCLUSION: The treatment of keratoconus 100 years ago used refractive surgery to improve visual function by modifying corneal shape.

Cornea↗

The risks of precipitating acute angle-closure glaucoma with the clinical use of mydriatic agents.

The risks of precipitating acute angle-closure glaucoma is always present when eyes have shallow anterior chambers, and early recognition of angle-closure glaucoma is important to prevent permanent loss of vision. Two groups of patients with acute angle-closure glaucoma are presented: in the first the attack was immediately preceded by the use of a mydriatic agent and in the second a mydriatic agent had been used previously without incident but the patient later presented with a spontaneous acute attack. A shallow anterior chamber, and in particular inequality of anterior chamber depths of greater than 0.2 mm, were important indicators of susceptibility to angle closure, which is more common in women than in men. Where there is a risk of angle closure, tropicamide 0.5% appears to be the safest mydriatic agent and should be followed by the administration of a miotic agent in susceptible individuals. The need to carry out a peripheral iridectomy in the other eye is stressed, irrespective of the age of the patient. A case of acute glaucoma after the use of oral drops that contained belladonna for nasal allergy further highlights the risks of the use of systemic mydriatic agents in susceptible individuals.

Acute Disease↗

Evaluation of ocular arterial changes in glaucoma with color Doppler ultrasonography.

The purpose of this study was to evaluate hemodynamic changes of the retrobulbar vasculature caused by different intraocular pressures with color Doppler ultrasonography. Fifty normal eyes in 25 patients, 13 patients with normal tension glaucoma, and 19 patients with acute glaucoma and increased intraocular pressure (greater than 30 mm Hg) were enrolled in this study. In 15 of 19 patients with acute glaucoma patients, follow-up color Doppler ultrasonography was also undertaken after laser peripheral iridectomy when the intraocular pressure had returned to normal. The peak systolic velocity, end diastolic velocity, resistive index, time average maximum velocity, and pulsatility index were compared in different vessels, including the central retinal artery, lateral posterior ciliary artery, medial posterior ciliary artery, and ophthalmic artery in each orbit. The peak systolic velocity, end diastolic velocity, and time average maximum velocity of the central retinal artery were significantly lower (P<0.01) in acute glaucoma patients than in the control group. The resistive index and pulsatility index of the central retinal artery were significantly higher (P<0.01) in acute glaucoma patients than in the control group. The end diastolic velocity of the lateral and medial posterior ciliary arteries was significantly lower in patients with acute glaucoma than in the control group, and the resistive index and pulsatility index of both of these arteries were significantly higher (P<0.001) in patients with acute glaucoma than in the control group. However, no statistical significantly differences were found in the peak systolic velocity or time average maximum velocity in either of the posterior ciliary arteries; similarly, no statistically significant differences were noted in any of the parameters in the ophthalmic artery between the control group and the group with acute glaucoma. The pulsatility index of the central retinal artery and of the lateral and medial posterior ciliary arteries was significantly lower (P<0.01) in acute glaucoma patients after laser therapy than in acute glaucoma patients before laser therapy. The resistive index of both posterior ciliary arteries was also significantly lower (P<0.004) in acute glaucoma patients after laser therapy than before laser therapy. All parameters for all vessels examined among the normal subjects, the patients with normal tension glaucoma, and the patients with acute glaucoma after laser therapy when the intraocular pressure had returned to normal showed no statistically significant differences. Color Doppler ultrasonography is a good modality for both imaging and studying the hemodynamics of the perioptic nerve vessels.

Aged↗

[Clinical signs and differential diagnosis of iris melanoma].

Iris melanoma is the rarest type of uveal melanomas. Only 4-5% of uveal melanomas occur on the iris. Although the iris can be easily examined due to its location, differentiation of melanocytic malformations such as naevi or melanomas is difficult for the examiner. According to publications by Rones and Zimmermann, histological examinations showed 22% of tumors to be malignant and 78% to be benign. This lead to iridectomy and iridocyclectomy as therapeutic solutions to gain ground over enucleation. Follow-up of the clinical signs, transillumination, ultrasonic biomicroscopy, iris fluorescein angiography and photo-documentation of the clinical signs can be of great help in diagnosis of pigmented iris tumours. Growth of the tumour, secondary glaucoma, hyphaema, significant vascularisation of the tumour and increasing extent of pigmentation can be signs of malignant behaviour.

Diagnosis, Differential↗

[An attempt at surgical management of haemorrhagic glaucoma (author's transl)].

A surgical method for the treatment of haemorrhagic glaucoma is discussed here. The operation implies Scheie's procedure without peripheral iridectomy, and the insertion of a silicon catheter. Prior to intraocular surgery cyclocryotherapy is employed in order to improve the basic condition. The long term mode of action of this surgical technique may be due to creating a favorable outset for the formation of secondary aqueous veins.

Adult↗

[Laser-treatment of the anterior segment of the eye with the new glaucoma research laser (author's transl)].

The possibilities for treatment of the anterior segment of the eye with the new glaucoma research laser, model 152, constructed by Britt-Corp. are reported on, along with the possibilities of vasodesolation, pupilplastics, iridontomies and iridectomies. Especially mentioned is the technic and possibility of laser-trabeculopuncture. This laser archieves remarkable success also in open-angle glaucoma and closed-angle glaucoma provided the technic is suitable. It is shown that all operations can be carried out by an ambulant patients and practicly without any complications. There are no problems during the aftertreatment for the doctor or for the patient.

Anterior Chamber↗

[Diagnostic problems in intraocular melanoma].

PURPOSE: To evaluate accuracy of the diagnosis, rate of advancement and therapeutic possibilities of intraocular malignant melanomas, basing on our one-year clinical material. MATERIAL AND METHODS: The total of 288 consecutive patients with suspicion or diagnosis of intraocular malignant melanoma, referred in the year 1997 to the Department of Ophthalmology CM UJ, were analysed. There were 121 males and 167 females, aged 22-76, mean 50. The period of time between the patient's first ocular symptoms and his visit to the ophthalmologist ranged between 7 days and several years. Besides routine ophthalmological examination each patient underwent USG and, if necessary AF, ICG, CT and IMR. RESULTS: Diagnosis of malignant melanoma was confirmed in 141 cases. Among these patients in 69 brachytherapy was applied, in 20 surgical resection of the tumor and in 52 enucleation. In 111 cases other following diseases were diagnosed: iris cysts, deficient iridectomy, iris nevus, choroidal nevus, metastatic tumors, age-related macular degeneration, myelinated nerve fibres, Leber-Coats syndrome, toxoplasmosis and granulomatous uveitis. In 36 cases the diagnosis was not exact and those patients remained under periodic clinical observation. CONCLUSIONS: Our study shows that in many patients intraocular malignant melanoma is diagnosed too late and in these cases enucleation is the only method of treatment. The most diagnostic challenges are connected with differentiation of choroidal melanoma from choroidal nevus and exudative form of age-related macular degeneration.

Adult↗

Familial occurrence of pseudoexfoliation in Canada.

BACKGROUND: Genetic factors may play an important role in pseudoexfoliation syndrome. We describe the familial occurrence of pseudoexfoliation in Canadian families. METHODS: Probands with pseudoexfoliation were referred to a tertiary care glaucoma service in Ottawa because of a family history of pseudoexfoliation or glaucoma, or both. Probands and family members who agreed to participate underwent a systematic interview and eye examination. The pseudoexfoliation status was classified as affected, suspect or unknown based on preestablished criteria for the diagnosis of pseudoexfoliation and glaucoma. RESULTS: Thirty-four members of 10 families were assessed (18 affected, 2 suspect and 14 status unknown). Six families had two or more generations with pseudoexfoliation, and four families had one generation affected. There was a predominance of females among the affected subjects (17:1), and transmission in all cases appeared to be maternal. Eight of the families were of Irish/Scottish ancestry. Nine (50%) of the affected subjects had cardiovascular disease. Affected subjects tended to be older than suspects and those whose status was unknown (mean age 77, 67 and 55 years respectively). Seven subjects were affected unilaterally and 11 bilaterally. Affected subjects had moderate angle pigmentation in both eyes (mean +2.7, where 0 = no pigment and +4 = dense homogeneous pigment). The mean intraocular pressure in both eyes was higher for the affected subjects (23.1 [standard deviation (SD) 8.6] mm Hg) than for the suspects (16.8 [SD 6.1] mm Hg) and those of unknown status (16.8 [SD 2.9] mm Hg). An enlarged cup:disc ratio was seen in the affected subjects (mean 0.62). Eleven (61%) of the affected subjects had open angles on gonioscopy, and five had occludable angles and required peripheral iridectomy. Ten (56%) of the affected subjects were classified as having glaucoma, and 14 (78%) had evidence of cataract formation in at least one eye. INTERPRETATION: Pseudoexfoliation appears to be transmitted matrilineally, which raises the possibility of mitochondrial inheritance, X-linked inheritance or autosomal inheritance with genomic imprinting. A larger study of families with pseudoexfoliation is necessary to clarify the mode of transmission and to identify the gene(s) involved in the etiology of this disorder.

Adult↗

Management of subluxated crystalline lenses with planned intracapsular cataract extraction and anterior chamber intraocular lens implantation.

PURPOSE: To review the visual and surgical outcome of planned intracapsular cataract extraction (ICCE) and anterior chamber intraocular lens (AC IOL) implantation for subluxated crystalline lenses. METHODS: Eight eyes of 7 patients with subluxated lenses which underwent planned ICCE, AC IOL implantation and peripheral iridectomy by one surgeon between September 1995 and November 1996 were prospectively followed-up to ascertain their visual and surgical outcome. RESULTS: There were 4 male and 3 female patients. Their mean age was 64.4 years (range, 39-86 years). Seven lenses were removed by cryoextraction while one was removed with the aid of a vectis. The mean post-operative follow-up was 11.6 months, (range, 3-22 months). Excluding 1 eye with pre-existing ocular pathology, all eyes achieved a best corrected visual acuity (BCVA) of 6/12 or better post-operatively. One of these eyes, in a schizophrenia patient, developed subluxation of the AC IOL and retinal detachment 11 months after the cataract surgery due to repeated eye rubbing. The final BCVA became 6/120 after successful repositioning of the AC IOL and retinal re-attachment surgery. One eye achieved a BCVA of 6/36 due to age-related macular degeneration. CONCLUSION: Our results show that planned ICCE and AC IOL implantation is a useful and safe procedure in the management of subluxated lenses.

Adult↗

[Surgical treatment of pigmented tumors of the iris and iridociliary region].

The authors present a group of six patients with pigmented tumours of the iris and the iridocorneal angle where they performed excision of the tumour by iridectomy (3 patients) or iridiocycletomyy (3 patients). In all six patients with a pigmented tumour of the iris an impaired blood-ocular fluid barrier was found and colouration of the tumour mass by fluorescein. In one patient a heavily pigmented tumour was detected which masked the vascular network. Impaired permeability was found more markedly at the margins. Histological examination confirmed in five instances melanoma of the iris, in one instance a pigmented naevus was involved. During the mean observation period of 32.5 months none of the patients developed a relapse or metastases. Consistent with the extent of the surgical intervention, within 6 months at the latest in all patients the disorder of the blood-ocular fluid barrier improved.

Adult↗

Management of severe proliferative vitreo-retinopathy with perfluorocarbon liquids and silicone oil.

12 patients of retinal detachment with advanced proliferative vitreoretinopathy were managed with intraoperative perfluoro-N-octane and postoperative silicone oil injection from March 1994 to June 1996 in Kaohsiung Medical University Hospital. The combined intraoprative procedures included posterior vitrectomy (12 eyes), membrane peeling (12 eyes), lower peripheral iridectomy (8 eyes), endo-photocoagulation (8 eyes), retinotomy (8 eyes), and retinal fixation with tack (1 eye). After a minimum of 10 months of follow up, the retina was successfully reattached in 10 (84%) of the 12 eyes, 5 of these eyes had stable tractional detachments on the anterior part of the scleral buckle. Seven patients (58.3%) regained vision of 5/200 or better. The rate of improvement by listing best corrected visual acuity after operation was 75%. We think that the ability to readily remove additional pre-retinal fibrous tissue after the retina was flattened with perfluorocarbon liquids allowed the surgeon to perform a further complete membrane dissection. It can therefore improve the success rate of surgery and hence decrease the rate of complications that was previously thought to be caused by sillicone oil.

Fluorocarbons↗