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Nick Mamalis

Publications and source records attributed to Nick Mamalis.

At least 55 records · Page 3Linked to original sources
PubMed2005

Salzmann's-like nodular degeneration following laser in situ keratomileusis.

We report the development of bilateral Salzmann's-like corneal lesions located at the site of laser in situ keratomileusis (LASIK) flap margins in 2 patients. These lesions resulted in ocular surface irritation as well as induction of irregular astigmatism and associated loss of best corrected visual acuity. Both patients had bilateral LASIK before the occurrence of the corneal lesions. A biopsy was performed on 1 nodule. The epithelium overlying this raised bluish-white corneal lesion appeared irregular in thickness, with replacement of Bowman's layer by periodic acid-Schiff positive thickened basement membrane-like material. Underlying this basement membrane was a layer of relatively regular, hypocellular, collagenlike connective tissue, which demonstrated hyalinization on trichrome staining. Based on these 2 cases, it seems possible that the hyposecretion of tears, decreased blink rate, and Dellen effect that often occur following LASIK could produce the corneal irritation needed to induce Salzmann's nodular degeneration.

Adult↗
PubMed2005

Postoperative localized opacification of the new MemoryLens design: analyses of an explant.

We describe a different form of opacification of the new MemoryLens intraocular lens model CV232, leading to a decrease in visual acuity and requiring explantation. A well-circumscribed, centrally/paracentrally located opacification of the optic was observed, with the aspect of a small "lens inside the lens." Histochemical and surface analyses revealed the presence of calcified deposits within a void in the optic substance. This void was seen as a linear optic breach in analysis of an optic cylindrical block cut through the area of opacification, from a sagittal view. The origins of the optic void are unclear.

Aged↗
PubMed2005

Surface calcification of a 3-piece silicone intraocular lens in a patient with asteroid hyalosis: a clinicopathologic case report.

OBJECTIVE: To illustrate the laboratory findings in a patient with bilateral asteroid hyalosis who presented with calcified deposits on a 3-piece silicone intraocular lens (IOL). DESIGN: Observational case report. METHODS: A 76-year-old diabetic woman underwent uneventful cataract surgery in 1994 with implantation of a silicone-optic polypropylene-haptic IOL in the left eye. A neodymium:yttrium-aluminum-garnet (Nd:YAG) laser posterior capsulotomy was performed 2 years after cataract surgery, but persistent whitish deposits were observed on the posterior optic surface of the lens. Over the next 3 years, the opacification increased in the region corresponding to the capsulotomy. The IOL was explanted/exchanged. The right eye had cataract surgery in 1995. The acrylic lens implanted in this eye developed no opacities after 6 years. MAIN OUTCOME MEASURES: Gross, microscopic, and surface analyses of the explanted IOL. RESULTS: Gross and light microscopic analyses revealed the presence of confluent crustlike deposits on the central area of the posterior optic surface, as well as Nd:YAG pits. Individual spherules exhibiting a Maltese-cross pattern under polarizing light were also observed. Energy dispersive x-ray spectroscopic analyses demonstrated the composition of the confluent deposits to be similar to hydroxyapatite. CONCLUSIONS: An association between asteroid hyalosis and dystrophic calcification of IOLs has been reported only with silicone plate haptic designs. The material opacifying the 3-piece silicone lens probably was derived from the asteroid bodies or from the process that results in this vitreous condition. Clinical evaluation of other pseudophakic patients with asteroid hyalosis will confirm if this phenomenon is restricted to silicone IOLs.

Aged↗
PubMed2004

Surface calcification of silicone plate intraocular lenses in patients with asteroid hyalosis.

PURPOSE: To report three cases in which a silicone-plate lens was explanted because of whitish deposits on the posterior optic surface. DESIGN: Observational case series with clinicopathological correlation. PATIENTS AND METHODS: In the three instances, the deposits were observed at least 2 years after uneventful cataract surgery. All of the patients had unilateral mild asteroid hyalosis in the concerned eye. After explantation of the lenses, gross and light microscopic analyses were performed. The posterior optic surfaces of the lenses also underwent scanning electron microscopy coupled with energy dispersive x-ray spectroscopy for analysis of the elemental composition of the deposits. RESULTS: Gross and light microscopic analyses revealed well-demarcated areas of whitish deposits on the posterior optic surface of the lenses, as well as multiple pits caused by Neodymium:yttrium aluminum garnet laser treatments. The deposits formed an amorphous layer with a "crustlike" appearance, which was confirmed by scanning electron microscopy. X-ray spectroscopy analyses demonstrated the composition of the deposits to be similar to hydroxyapatite. CONCLUSIONS: The material opacifying the lenses was probably derived from the asteroid bodies or from a similar process that results in this vitreous condition. We were unaware of this association between asteroid hyalosis and late postoperative dystrophic calcification of silicone lenses.

Aged↗
PubMed2004

Capsular bag opacification after experimental implantation of a new accommodating intraocular lens in rabbit eyes.

PURPOSE: To evaluate the development of capsular bag opacification in rabbit eyes after implantation of an intraocular lens (IOL) designed to minimize contact between the anterior capsule and the IOL and ensure expansion of the capsular bag. SETTING: David J. Apple, MD Laboratories for Ophthalmic Devices Research, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. METHODS: Ten New Zealand white rabbits had a study IOL (new accommodating silicone IOL [Synchrony, Visiogen, Inc.]) implanted in 1 eye and a control IOL (1-piece plate silicone IOL with large fixation holes) implanted in the other eye. Intraocular lens position, anterior capsule opacification (ACO), and posterior capsule opacification (PCO) were qualitatively assessed using slitlamp retroillumination photographs of the dilated eyes. Anterior capsule opacification and PCO were graded on a 0 to 4 scale after the eyes were enucleated (Miyake-Apple posterior and anterior views after excision of the cornea and iris). The eyes were also evaluated histopathologically. RESULTS: The rate of ACO and PCO was significantly higher in the control group. Fibrosis and ACO were almost absent in the study group; the control group exhibited extensive capsulorhexis contraction, including capsulorhexis occlusion. Postoperative IOL dislocation into the anterior chamber and pupillary block syndrome were observed in some eyes in the study group. CONCLUSIONS: The special design features associated with the study IOL appeared to help prevent PCO. Complications in the study group were probably caused by the increased posterior vitreous pressure in rabbit eyes compared to human eyes and the relatively large size of the study IOL relative to the anterior segment of rabbit eyes.

Animals↗
PubMed2004

Posterior capsule opacification in rabbit eyes implanted with hydrophilic acrylic intraocular lenses with enhanced square edge.

PURPOSE: To evaluate the development of posterior capsule opacification (PCO) after implantation of single-piece hydrophilic acrylic intraocular lenses (IOLs) with an enhanced square edge. SETTING: John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. METHODS: The standard 570H Centerflex (Rayner Ltd.) design was compared to 2 new designs with enhanced square edges: the 570E and the 570C. Ten IOLs of each type were implanted in a randomized manner by the same surgeon in 15 pigmented rabbits. After a follow-up of 3 weeks, the rabbits were killed and the eyes were analyzed from the posterior view. The intensity of central PCO, peripheral PCO, and Soemmering's ring formation was graded from 0 to 4. The area of Soemmering's ring was graded from 0 to 4 based on the number of quadrants involved. Other parameters analyzed were capsulorhexis coverage of the IOL edge and IOL centration and fixation. Results from the posterior view were complemented by histopathological evaluation. RESULTS: Posterior capsule opacification was lowest in the 570C group, highest in the 570H group, and intermediate in the 570E group. There was a statistically significant difference between the 3 groups in peripheral PCO (P = .039). No significant difference was found between the groups in the other parameters analyzed. When cell ingrowth occurred with the 570H, it started at the optic-haptic junctions, as observed during the clinical follow-up and confirmed by gross and histopathological analyses. CONCLUSIONS: The square optic edge is the most important IOL design feature for PCO prevention. However, it should be present for 360 degrees around the IOL optic to provide an effective barrier effect.

Acrylic Resins↗
PubMed2004

Complications of foldable intraocular lenses requiring explantation or secondary intervention--2003 survey update.

The sixth annual survey of complications associated with foldable intraocular lenses (IOLs) requiring explantation or secondary intervention was sent to members of the American Society of Cataract and Refractive Surgery and the European Society of Cataract and Refractive Surgeons. Preoperative data about visual acuity, patient signs and symptoms, and complications requiring IOL removal were evaluated. Complications were then tabulated for each of the following major foldable IOL groups: 3-piece monofocal silicone, 3-piece hydrophobic acrylic, 1-piece hydrophobic acrylic with haptics, 3-piece hydrophilic acrylic (hydrogel), 1-piece hydrophilic acrylic (hydrogel), 1-piece plate-type silicone, 3-piece multifocal silicone, and Collamer. Two hundred seventy-three surveys were returned for evaluation. Dislocation/decentration, incorrect lens power, IOL calcification, and glare/optical aberrations were the most common reasons for removing foldable IOLs. Good surgical technique, accurate IOL power measurements, and high manufacturing standards for foldable IOL materials and designs are the most important factors in avoiding complications with foldable IOLs.

Acrylic Resins↗
PubMed2004

Wavefront corrections of intraocular lenses.

This article describes two currently available intraocular lenses (IOLs) that have special design features allowing for correction of optical aberrations other than spherical refractive errors. Although they are not yet fully "customized" lenses, their development has involved average aberrations measured with wavefront technology. An experimental IOL manufactured with a special technology is also described that, when used in conjunction with wavefront sensing, has the potential for full customization.

Animals↗
PubMed2004

Late postoperative opacification of a hydrophilic acrylic (hydrogel) intraocular lens: a clinicopathological analysis of 106 explants.

PURPOSE: To report clinical, pathologic, histochemical, ultrastructural, and spectroscopic analyses of MemoryLens intraocular lenses (IOLs) explanted from patients who had visual disturbances caused by postoperative opacification of the lens optic. DESIGN: Noncomparative, large case series with clinicopathologic correlation. PARTICIPANTS: A total of 106 hydrophilic acrylic IOLs of the same design explanted from 106 different patients. All patients had decreased visual acuity at presentation approximately 2 years after cataract surgery, associated with a whitish fine granularity on the optical surfaces of the IOLs. METHODS: The explanted IOLs were submitted to the John A. Moran Eye Center and were examined under light microscopy, histochemically, and with scanning electron microscopy (SEM) equipped with an energy dispersive x-ray spectroscopy detector with light element capabilities (EDS). MAIN OUTCOME MEASURES: The IOLs were examined for distribution, structure, and composition of the deposits causing opacification of their optic components. RESULTS: The average interval between lens implantation and opacification was 25.8+/-11.9 months. The most frequently associated medical and ophthalmic conditions were diabetes and glaucoma. However, some patients did not have any preexisting medical or ophthalmic conditions. Most of the IOLs had been implanted in 1999 and 2000. Microscopic analyses revealed the presence of multiple fine, granular deposits of variable sizes on the anterior and posterior optic surfaces, especially on the anterior surface. The deposits stained positive for calcium. The EDS confirmed the presence of calcium and phosphate within the deposits. CONCLUSIONS: The results obtained suggest the surface deposits to be composed, at least in part, by calcium and phosphate. A special polishing technique used in the manufacture of most of these IOLs may have caused changes in the lens surface leading to deposit formation. Further studies should be undertaken to confirm this hypothesis.

Acrylic Resins↗
PubMed2004

Late postoperative opacification of MemoryLens hydrophilic acrylic intraocular lenses: case series and review.

PURPOSE: To report clinical and spectrographic analyses of 2 explanted hydrophilic acrylic intraocular lenses (IOLs). SETTING: John A. Moran Eye Center, Salt Lake City, Utah, USA, and Johannes Gutenberg-University, Department of Ophthalmology, Mainz, Germany. METHODS: We report 6 cases of opacification of MemoryLens IOLs (Ciba Vision) that occurred approximately 2 years after implantation. The anterior and posterior surfaces of the IOLs had a white, frosted appearance, and the IOLs' interior looked brown, similar to the appearance of a brunescent cataract. Two of the IOLs were explanted because of a significant decrease in visual acuity. The IOLs were sent for further clinicopathologic analysis including scanning electron microscopy and energy dispersive x-ray spectroscopy (EDX). RESULTS: Microscopic analysis revealed multiple, fine, granular deposits of various sizes on the surface of the lens optics. The EDX analysis showed the presence of calcium within the deposits. CONCLUSIONS: Our cases show that hydrophilic acrylic IOLs can opacify even years after implantation. Analysis of the explanted IOLs revealed calcification.

Acrylic Resins↗
PubMed2004

Revised Miyake-Apple technique for postmortem eye preparation.

We describe a revised Miyake-Apple technique to prepare cadaver eyes. A plastic mold is used to hold the globe for marking and to facilitate inverting the globe. This decreases vitreous loss and creates a more secure eye. The method is easy, decreases the learning curve, and increases the quality of the prepared eyes.

Cadaver↗
PubMed2003

Cataract treatment in the beginning of the 21st century.

PURPOSE: To describe the principles upon which present day cataract treatment success resides. DESIGN: Literature review and collective experience of the authors. RESULTS: Surgical removal remains the standard treatment for cataract now and in the foreseeable future. Ultrasound cataract removal with a foldable "in-the-bag" intraocular lens with a truncated edge treated for dysphotopsia best correlates with core treatment principles, as we now understand them. Improving refractive results is an important trend. The worldwide burden of this problem is immense. CONCLUSIONS: While results for treatment of cataracts are excellent today, improvements in safety and refraction precision are needed. Other approaches are desperately needed to stem the worldwide tide of cataract related ocular dysfunction.

Cataract↗