5 research outputs found
Comparison of short term clinical results following implantation of acrylic foldable intraocular lens and polymethyl meth acrylate rigid intraocular lens in patients with diabetes mellitus
The modern cataract surgery has given good visual results, but this could deteriorate over times because of Posterior Capsule Opacification (PCO) which is the most frequent complication after cataract extraction. The blood-aqueous as well as blood-retinal barrier damage in diabetic eyes are likely to pose an increased risk of PCO, which can be prevented by improved surgical techniques and by selecting ideal intraocular lens materials and designs.
AIMS AND OBJECTIVES:
To compare the post-operative visual outcome and incidence of posterior capsular opacification after implantation of Hydrophobic Acrylic and poly methyl methacrylate (PMMA) intraocular lenses (IOLs).
MATERIALS AND METHODS:
Ethical clearance was obtained from the institutional ethics board. After the implantation of PMMA and Acrylic IOLs, all patients with Type 1 and Type 2 diabetes mellitus were studied during the study period from April 2014 to September 2014 as per the protocol excel.
INCLUSION CRITERIA:
1. Patient with age group 40-70 years with uncomplicated senile cataract.
2. Eligible cataracts in diabetics without retinal change
3. Using phacoemulsification technique.
4. Using continuous curvilinear capsulorrhexis technique.
EXCLUSION CRITERIA:
1. Patients with history of previous ocular diseases, surgery.
2. Patients with history of ocular trauma. previous glaucoma , corneal pathologies.
3. Operative complications, posterior segment pathologies.
The patients underwent complete ocular examination pre-operatively. It includes, UCVA and BCVA, pupillary reaction, IOP measurement , Slit lamp examination of anterior segment, cataract grading and posterior segment evaluation using +90D lens and B-scan was done. IOL power was calculated by SRK II formula. Diabetics were taken up for surgery only if PPBS was <140 mg /d1.
After obtaining consent from the patient, half of these patients were implanted with PMMA and remaining with Acrylic IOLs, and followed for a period of 6 months. During their follow-up UCVA, BCVA, Posterior capsular opacification &its grading were noted.
CONCLUSION:
Acrylic IOLs produce better visual result in diabetic patients than PMMA IOLs, and that acrylic IOLs may be a better choice in diabetics when PCO is taken into consideration. However, this must be confirmed by further randomized, prospective, and larger studies with longer follow up
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Digital Images Assessment of Posterior Capsule Opacification
A digital imaging system has been developed for the objective assessment of severity and morphology of posterior capsule opacification (PCO). The system is based on a Nikon FS-2 photo slit-lamp and a Kodak DCS 100 digital camera system. The slit-lamp was used with conventional (forward) illumination and studies were carried out to determine the best combination of slit-lamp and camera parameters to optimize the images. These were found to be a slit beam width of 3.5mm, slit angle of 45°, film speed (ISO) of 1600 for the camera and 800 for the digital storage unit (DSU), exposure compensation 0, flash intensity 2 and a magnification of 25x. A fixation stimulus was developed since it was shown to decrease the variability of the images and reduce the possibility of unwanted reflexes affecting the area of interest. In all cases a central 3mm x 3mm area of the posterior capsule, centred on the pupil, was analysed. The image processing software used throughout the work was Image Pro+ v4.51 (Media Cybernetics, Silver Spring, MD).
For validating the system, subjects who had previously had uncomplicated cataract surgery were recruited from the Nd:YAG capsulotomy clinics of the Royal Eye Unit at Kingston. Intra-observer repeatability was assessed by taking 6 repeat images for each of 10 subjects. The coefficient of variation for total spectral power in the image, a measure of the severity of opacification, was 1.5%. Inter-observer repeatability was tested for 3 observers, an ophthalmologist, an optometrist and a non-clinician, by recording 2 images for each observer for each of 9 subjects. There was a 6 fold increase in the limits of agreement when the non-clinician was involved indicating that suitable training is required to use the system in a repeatable fashion.
Severity of opacification was measured by calculating the log of the total spectral power in the Fourier Transform image of the area of interest. Results on 45 eyes correlated well with subjective grading of PCO by an experienced ophthalmologist: Within the 3 morphological groups, fibrotic, mixed and pearl, correlation coefficients of 0.909, 0.864 and 0.713 were found, which were all statistically significant.
Morphological classification was carried out by developing a simple expert system. The rules in the knowledge base were derived from known histological features of PCO and clinically observed changes. The weighted kappa score for agreement between the objective classifier and an experienced ophthalmologist was 0.61 indicating a good level of agreement. However 14 out of 45 cases did not exhibit agreement. It may be possible with further work to improve the classification rules to reduce this number.
New methods have been presented for objectively measuring the severity and morphologically classifying PCO. The system developed in this work shows distinct potential for use within primary care environments since it uses techniques and instruments whose operation is familiar to all practitioners involved. The validation studies presented here demonstrate variability in the measurements that is largely in agreement with previously published systems
Halbjahresergebnisse einer neuen faltbaren Hinterkammerlinse aus Acryl, AcrySof® MA60BM
Das Forschungsziel dieser Arbeit war die Abklärung der Frage, ob sich in implantierten Intraokularlinsen der Marke Acrysof®, die in Deutschland kurz nach deren Markteinführung erworben wurden, Mikrovakuolen im Optikkörper befinden. Diese sogenannten Glistenings, die der Hersteller auf eine neuartige Verpackung zurückführte, welche ausschließlich in den Vereinigten Staaten Verwendung fand, führten in den USA zu Explantationen und zum Rückruf so verpackter Kunstlinsen dieses Typs. Unser Arbeitsprogramm umfaßte hauptsächlich die Untersuchung von Patienten, bei denen eine Acrysof®-Intraokularlinse implantiert wurde, an der Spaltlampe und anschließende Dokumentation mittels Fotospaltlampe. Zusätzlich wurden Sehschärfebestimmungen durchgeführt. Analog wurden Untersuchungen und Dokumentationen bei Patienten, denen im gleichen Zeitraum und vom gleichen Operateur eine herkömmliche PMMA-Kunstlinse implantiert wurde, durchgeführt. In allen untersuchten Intraokularlinsen des neuen Modells aus Acryl konnten Mikrovakuolen festgestellt und fotografisch dokumentiert werden. Diese Veränderungen konnten in keiner der PMMA-Kunstlinsen beobachtet werden. In unseren Ergebnissen fanden sich sonst durchgehend Hinweise auf die mittlerweile von anderen gewonnenen Erkenntnisse über die neue Linse. Es konnten keine Hinweise auf eine Visusminderung durch die Glistenings festgestellt werden. Die Analyse der Literatur ergab, daß nach dem heutigem Stand der Erkenntnisse über die Glistenings, von einer Flüssigkeitsaufnahme in den Optikkörper der IOL ausgegangen wird. Die Flüssigkeit sammelt sich in einige mikrometer großen Räumen in der Polymerstruktur der Kunstlinse. Diese Mikrovakuolen werden durch die Brechkraftdifferenz zwischen deren Inhalt und dem IOL-Material optisch sichtbar und erscheinen bei der Spaltlampenuntersuchung als multiple Glitzerpunkte. Experimentelle Arbeiten haben gezeigt, daß die Ausbildung der Mikrovakuolen durch Temperaturschwankungen und durch die Anwesenheit von Serum begünstigt wird. Ein verstärktes Vorkommen der Glistenings bei Patienten, bei denen sich durch Beeinträchtigung der Blut-Kammerwasser-Schranke oder der Blut-Retina-Schranke, Serumbestandteile im Kammerwasser befinden können, hier sind besonders Diabetiker zu nennen, wurde von einigen Autoren berichtet. Auch wir konnten bei einer nachträglichen Auswertung unserer Unterlagen Hinweise darauf finden, daß es bei solchen Patienten zur verstärkten Glisteningbildung kommt. Die Aussage der Herstellerfirma, die Glistenings hingen mit der neuartigen Verpackung und Sterilisation der IOLs in dem AcryPak-System, welches nur in den USA zum Einsatz kam und 1995 vom Markt genommen wurde, zusammen, wurde durch unsere Ergebnisse widerlegt. Besonders die frühere englischsprachige Literatur spiegelt einen Konsens mit der vom Hersteller vertretenen Auffassung wider. Neuere Arbeiten, die unsere Ergebnisse bestätigen weisen auf ein Poster auf einem Kongress 1999 in Seattle als erstes bekanntwerden von Glistenings in herkömmlich verpackten AcrySof®-IOL hin, obwohl schon frühere Berichte von Autoren aus Europa, auch von unserer Arbeitsgruppe, vorlagen. Die Mikrovakuolen haben nur in sehr seltenen Einzelfällen, bei denen es zu massenhaftem Vorkommen gekommen war, zu Beeinträchtigungen der Sehfunktionen geführt und eine Explantation erforderlich gemacht. Trotzdem sind weitere Forschungen, für die wir einige Ansätze vorschlagen, notwendig. Auch das Vorkommen von schwerwiegenden Trübungen bei anderen Kunstlinsentypen zeigt die Notwendigkeit für verstärkte Forschungen und gesetzliche Regulierungen auf diesem Gebiet. Insbesondere die hervorragend niedrigen Nachstarraten, die mit der Implantation von AcrySof®-Kunstlinsen einher gehen, berechtigen jedoch zu ihrer Weiterverwendung. Während es unwahrscheinlich scheint, daß die Glistenings noch schwerwiegende Probleme bereiten werden, so ist jedoch gesichert, daß durch die Verwendung von AcrySof®Kunstlinsen weniger YAG-Laser-Kapsulotomien notwendig sind. Daß sich damit auch die mit diesem Eingriff verbundenen Kosten und Komplikationen reduzieren ist selbstredend. Der Verlauf der Forschungen zu diesem Thema wird dargelegt. Die Notwendigkeit präziserer Studienaufbauten und besserer technischer Ausstattung wird deutlich. Durch den fortgeführten Einsatz der AcrySof®-IOL wurde die ophthalmologische Sichtweise der IOL verändert. Die IOL wird heute als Implantat betrachtet, welches die Aphakie korrigiert aber auch den Nachstar verhüten soll. Im kleinen Rahmen der Entwicklungsgeschichte der IOLs selbst, könnte dies den Beginn einer neuen IOL-Generation bedeuten.This study has been conducted to clarify the presence of microvacuoles within the optics of implanted AcrySof®-brand intraocular lenses (IOLs). These lenses were implanted in the Federal Republic of Germany, shortly after they became commercially available in December 1994. According to the manufacturing company, microvacuoles, also called glistenings, were caused by a new type of packaging which was used in the USA only. This situation led to explantations of IOLs and to the recall of lenses packed in that new manner. The main thrust of our fesearch program was the slitlamp examination of patients who had an implanted AcrySof®-lens. The findings were documented by means of slitlamp-photography. In addition, visual acuity tests were conducted. At the Same time, analog examinations and documentations of a second group of patients were done. These patients had been operated by the Same surgeon ,during the Same months as the patients of the AcrySof®-Group, but had common poly(methy1 methacry1ate)-I0Ls in their eyes. In all acrylic intraocular lenses microvacuoles could be found and documented. This phenomenon could not be Seen in any of the examined poly (methyl methacrylate)-IOLs. Our research also identified newer findings published by other investigators concerning the Acrysof®-IOL, We did not detect any signs of visual acuity reduction caused by the glistenings. Our literature search reveals that the glistenings have to be looked at as fluid uptake from the aqueus to the optic-body of the IOL. The fluid gathers in spaces within the polymer-structure of the IOL. The glistenings have a dimension of a few micrometers. Due to the different refractive indices of the content of the vacuoles and the IOL-material, the microvacuoles become visible as multiple pinpoint glistenings. Experimental work has shown that the formation of the glistenings increases with fluctuating temperature and the presence of serum. Some investigators have reported an increased prevalence of glistenings in patients who may have serum-components in the aqueus, caused by a compromised blood-aqueus-barrier or a compromised blood-retina-barrier, e. g. persons with diabetes. In this regard a reevaluation of our data showed signs of increased glistening-formation in above mentioned patients. The statement of the manufacturing company, that glistenings coincide with the packaging- and sterilisation of the IOLs with the new AcryPak-system, could be disproved by our results. The early literature in English shows a Consensus with the manufacturer's assertion. However, recent studies, referring to a poster presentation at the 1999 ASCRS meeting in Seattle, as the first publication of glistenings in commonly packed AcrySof®-IOLs, confirm our results. Earlier reports had been published by european authors, including our study-group. Although glistenings have resulted in very few explantations due to reduced visual accuity further research on this topic is necessary. Furthermore, the existence of severe opacities in other types of IOLs, suggests the necessity of increased research and legal regulation concerning this topic. The very low rates of posterior capsule opacification (PCO) following AcrySof®-IOLimplantations justify their use. While it is not likely that the glistenings will cause any severe problems, it is evident that implantation of AcrySof®-IOLs results in lower laser-capsulotomy-rates with a decreasing number of capsulotomy-associated complications and healthcare-cost-reduction. The Course of scientific research on the PCO-preventive effect of the AcrySof®-IOL is described in our discussion. We conclude that studies should be planned more precisely and should be conducted with equipment of higher technical standards. The continuous use of AcrySof®-IOLs changed the ophthalmologists' understanding of IOLs as such. Today the IOL is looked upon as an implant that corrects aphakia, but should also prevent PCO. From the perspective of the history of IOLs, this could mark the beginning of a new generation of IOL