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David J Spalton

Publications and source records attributed to David J Spalton.

14 recordsLinked to original sources
PubMed2006

Hydrophobic acrylic and plate-haptic silicone intraocular lens implantation in diabetic patients: pilot randomized clinical trial.

PURPOSE: To compare the capsular and uveal reaction after implantation of a plate-haptic silicone intraocular lens (IOL) (C11UB, Chiron) and a hydrophobic acrylic (AcrySof MA60, Alcon) IOL in diabetic patients. SETTING: Moorfields Eye Hospital and St. Thomas' Hospital, London, United Kingdom. METHODS: Thirty-five diabetic patients were recruited consecutively and randomly assigned to have implantation of either of the 2 IOLs. The percentage area of posterior capsule opacification (PCO), anterior capsule contraction (ACC), and postoperative inflammatory indices (flare and cells) were assessed objectively at 2 to 3 weeks, 6 months, and 1 year. Between-group and within-group analyses were conducted using the Student t test or Mann-Whitney test and Friedmann test, respectively. RESULTS: Between-group analysis showed the percentage area of PCO was significantly greater in patients with plate-haptic silicone IOLs at 6 and 12 months (P = .002). At 6 months, ACC was significantly greater in the plate-haptic group (P = .04), but the difference was not significant at 12 months. There was higher flare in the hydrophobic acrylic IOL group than in the plate-haptic silicone IOL group at 2 to 3 weeks (P = .08). Within-group analysis showed that over the follow-up period, the plate-haptic silicone group, but not the hydrophobic acrylic group, had a progressive increase in PCO (P = .003). In the hydrophobic acrylic group, but not the plate-haptic silicone group, there was a significant reduction in the mean anterior chamber flare value (P = .01). There was no significant difference in visual acuity or contrast sensitivity at any postoperative visit. CONCLUSION: In diabetic patients, hydrophobic acrylic IOLs can lead to an increased flare in the early postoperative period but they seem to be more favorable than plate-haptic silicone IOLs because the latter lead to more PCO.

Acrylic Resins↗
PubMed2005

Factors that influence the development of posterior capsule opacification with a polyacrylic intraocular lens.

PURPOSE: To identify factors that contribute to posterior capsule opacification (PCO) after implantation of a 5.5 mm polyacrylic (IOL). DESIGN: A retrospective analysis of a cohort of sequential images taken from the PCO database at St. Thomas' Hospital, London, to include all patients with an AcrySof MA30 lens and a 1-year retroillumination image. METHODS: Records of age, gender, axial length, and PCO measurements using the POCO software system were available. Images were divided into those with greater or less than 10% PCO. The degree of rhexis-IOL contact was recorded in clock hours. RESULTS: Images of 60 eyes were analyzed. Twenty-one eyes had more than 10% PCO. No correlation was found between PCO and age, gender, or axial length. Forty-eight eyes (80%) had some loss of rhexis-IOL contact. These eyes had increased PCO (P < .001) compared with eyes with complete IOL-rhexis contact. More PCO developed when the rhexis was partly on and partly off the IOL. CONCLUSIONS: PCO is reduced when the rhexis is in complete contact with the anterior IOL surface. The failure to achieve this accounts for the majority of increased PCO seen in patients implanted with this IOL model. PCO formation is related to surgical technique as well as IOL design, and comparisons cannot be made between IOLs without taking this into consideration. These results support the trend to the use of larger optic IOLs to prevent PCO and also support the "capsule compression" theory of PCO prevention.

Acrylic Resins↗
PubMed2005

Fellow eye comparison between the 1CU accommodative intraocular lens and the Acrysof MA30 monofocal intraocular lens.

PURPOSE: To examine the near visual clinical performance of an accommodative intraocular lens (IOL) when compared with a standard monofocal IOL in a fellow eye comparison. DESIGN: Prospective, randomized fellow eye comparison. METHODS: Thirty patients (60 eyes) with bilateral cataracts but otherwise normal eyes were recruited from a single university hospital cataract waiting list. Patients were randomized to receive either the 1CU accommodative IOL in their first eye or the Acrysof MA30 monofocal IOL. The alternative lens was then implanted in the second eye 4 to 6 weeks later. At all follow-up visits, a full assessment was made of distance, near and reading visual performance, and accommodative amplitude. RESULTS: Data are available for all patients at 6 months and 20 patients at 1 year. At 6 months, no difference was found in distance-corrected visual acuity between the two IOLs. Of the 1CU eyes, nine patients (30%) could read J6 or better at a reading speed of 80 words/min or better. In these nine patients, the mean difference in the amplitude of accommodation between the two eyes was 0.71 diopters. CONCLUSIONS: No measurable variable distinguished eyes that developed functional reading vision from those that did not. The accommodative IOL appears to produce improved near vision in some eyes, but it does not work in all eyes, and in eyes where there is apparent accommodation, there is a discrepancy between subjective reading performance and the modest measured increase of accommodative amplitude.

Accommodation, Ocular↗
PubMed2005

Comparison of posterior capsule opacification rates between hydrophilic and hydrophobic single-piece acrylic intraocular lenses.

PURPOSE: To determine the effect of intraocular lens (IOL) material on the development of posterior capsule opacification (PCO) at 1 year. SETTING: Department of Ophthalmology, St. Thomas' Hospital, London, United Kingdom. METHODS: One hundred six eyes of 53 patients with bilateral cataract and no other ocular comorbidity were prospectively randomized to receive a hydrophobic acrylic or hydrophilic acrylic single-piece IOL in the first eye to have surgery. The alternate IOL was implanted in the fellow eye 4 to 6 weeks later. All surgery was performed by a single surgeon. Postoperative follow-up was 1 day, 1 and 6 months, and 1 year. At each visit, the best corrected high- and low-contrast visual acuities were assessed and a high-intensity digital retroillumination photograph was taken. Posterior capsule opacification was assessed from the digital images by a single operator using a dedicated software program and calculated as the percentage area of opacified capsule. RESULTS: One year postoperatively, the median percentage area of PCO was 50.3% in the hydrophilic IOL group and 4.9% in the hydrophobic IOL group (P<.001). The difference in PCO was not accounted for by loss of contact between the capsulorhexis and IOL surface. Further analysis showed that lens epithelial cells tended to invade the posterior capsule at the haptic-optic junction. This was more marked in the hydrophilic IOL group. CONCLUSIONS: The rate of PCO was significantly higher with the hydrophilic IOL. However, the results cannot be attributed to the IOL material alone as they show the importance of both IOL material and design.

Acrylic Resins↗
PubMed2004

Effect of 1-piece and 3-piece AcrySof intraocular lenses on the development of posterior capsule opacification after cataract surgery.

PURPOSE: To evaluate the effect of 1-piece and 3-piece hydrophobic acrylic intraocular lenses (IOLs) on posterior capsule opacification (PCO) after cataract surgery. SETTING: Ophthalmology departments of 3 hospitals in the United Kingdom and Germany and the Department of Physics at a United Kingdom university. METHODS: A series of 131 patients having cataract surgery had implantation of an acrylic 1-piece (SA30AL) or an acrylic 3-piece (MA30BA) IOL (AcrySof, Alcon). Surgery was performed according to standardized protocol by a single surgeon at each hospital. Posterior capsule opacification was assessed using digital retroillumination photography. All images were analyzed at a single center according to a standard protocol. Data were analyzed 6 months and 1 year after surgery. RESULTS: There was no statistically significant difference in the percentage area of PCO between the 1-piece (mean 16.0% +/- 15.7% [SD]) and 3-piece (mean 13.6% +/- 19.8%) cohorts 6 months and 1 year after surgery (P =.0664). CONCLUSION: There was no evidence of a difference in the area of PCO after cataract surgery between 1-piece and 3-piece IOLs, which were otherwise matched for material and lens geometry.

Acrylic Resins↗
PubMed2004

POCOman: new system for quantifying posterior capsule opacification.

PURPOSE: To describe a new method of measuring posterior capsule opacification (PCO) and intraocular lens (IOL) rotation and report the validation of the method. SETTING: Ophthalmology Department, St. Thomas' Hospital, and Medical Imaging, Department of Physics, King's College, London, United Kingdom. METHOD: A new interactive software program, POCOman, was developed for the semiobjective assessment of PCO. Digital images of the posterior capsule, which can be acquired by any technique, are analyzed by the observer to determine the percentage area of PCO and assign a severity score. The system was validated by comparing it to clinical slitlamp evaluation of PCO and automated POCO system analysis using a library of 100 images taken from archives. The software also measures sequential IOL rotation for the evaluation of toric IOLs. RESULTS: An image could be analyzed in approximately 2 minutes. The results of the POCOman system correlated well with the results of the automated POCO system and clinical evaluation. CONCLUSIONS: The POCOman is an effective, user-friendly system for quantifying PCO. It can be obtained for free and has advantages over other methods.

Cataract↗
PubMed2003

Predicting posterior capsule opacification: value of early retroillumination imaging.

PURPOSE: To investigate the value of early retroillumination imaging of the posterior capsule in predicting the eventual development of posterior capsule opacification (PCO). SETTING: Ophthalmology Department, St. Thomas' Hospital, and Department of Physics, King's College, London, United Kingdom. METHODS: All patients with retroillumination images of the posterior capsule taken 6 months and 2 years after uneventful phacoemulsification with in-the-bag intraocular lens (IOL) implantation were selected. The images were taken using the same hardware and analyzed with the same software to calculate the percentage area of the posterior capsule covered by lens epithelial cells. The percentage area of PCO with all IOL types 6 months postoperatively was correlated with that at 2 years. RESULTS: One hundred forty patients had analyzable images at 6 months and 2 years. Of these, 63 had a poly(methyl methacrylate) (PMMA) IOL (Pharmacia 812A or Storz P497UV), 33 an acrylic (Alcon AcrySof MA30 or SA30), 22 a silicone (Allergan SI-30), and 22 a hydrophilic acrylic (Bausch & Lomb Hydroview H60). The correlation of the percentage area of PCO at 6 months with that at 2 years resulted in an r value of 0.71 (P <.0001) in the entire group. The r value was 0.48 in the PMMA group and 0.86 in the foldable IOL group (P <.0001) (r value: AcrySof, 0.66; silicone, 0.82; Hydroview, 0.75). CONCLUSIONS: Retroillumination imaging of the posterior capsule 6 months after cataract surgery predicted the PCO outcome at 2 years in eyes with foldable IOLs.

Acrylic Resins↗
PubMed2003

In vitro model for the study of human posterior capsule opacification.

PURPOSE: To develop and evaluate a model for the organ culture of human lens capsules that reduces problems inherent in preexisting models for the study of in vitro posterior capsule opacification (PCO). METHODS: Human lenses (N = 110) were isolated from donor eyes and supported externally within a lens holder system by medical-grade cyanoacrylate glue, allowing visualization of the entire capsular bag. After capsulorhexis and lens extraction were performed, the capsule specimens were maintained at physiological conditions for up to 4 weeks. The area of lens epithelial cell (LEC) coverage over the posterior capsule surface was determined objectively on a daily basis using a graticule. Lens epithelial cell behavior was correlated with clinical data and other in vitro PCO models. RESULTS: Cyanoacrylate glue did not appear to be toxic to LECs at the concentration used. The amount of viable epithelium after nuclear extraction was dependent on the age and postmortem time of the specimen. Viable LEC cultures were obtained from eyes up to 9 days postmortem. The time from death to culture or from enucleation to culture did not influence LEC viability if it was fewer than 5 days. The LEC proliferation rates and confluence times were age dependent and correlated closely between pairs of eyes. CONCLUSIONS: Results show that the lens holder model is a more physiological method for supporting the capsule and is a robust, reproducible system for the study of LEC migration and proliferation. It allows visualization within the entire capsular bag. Intraocular lenses can be implanted in this system in a way that more closely resembles the in vivo scenario. This model can be used to evaluate therapeutic measures to prevent PCO.

Adolescent↗
PubMed2003

The effect of posterior capsule opacification on visual function.

PURPOSE: To investigate how posterior capsule opacification (PCO) affects visual function in pseudophakic eyes. METHODS: One hundred and six eyes that had undergone uncomplicated phacoemulsification were recruited sequentially. Patients with surgical complications or other ocular disease were excluded. PCO was assessed by a digital retroillumination camera using a software program based on the analysis of texture in the image, and the percentage area within the central 3-mm zone of the posterior capsule was calculated. Visual function assessment included Early Treatment Diabetic Retinopathy Study (ETDRS) high- and low-contrast visual acuity, contrast sensitivity with the Pelli-Robson and CSV-1000 grating charts, and forward light-scatter by the direct-compensation method (van den Berg). RESULTS: The percentage PCO required for decline in high-contrast ETDRS was 78%; for low-contrast acuity and Pelli-Robson, 46%; for CSV-1000 contrast sensitivity, 38% to 51%; and for forward light-scatter, less than 1% PCO. CONCLUSIONS: Central PCO affects psychophysical test results with differing degrees of sensitivity. Forward light-scatter is the most sensitive, followed by contrast sensitivity and visual acuity.

Aged↗
PubMed2002

The effect of texturing the intraocular lens edge on postoperative glare symptoms: a randomized, prospective, double-masked study.

OBJECTIVE: To determine whether texturing the optic edge of the intraocular lens reduces photic symptoms in patients with square-edged acrylic intraocular lense implants. METHODS: Sixty patients underwent routine phacoemulsification performed by a single surgeon and were prospectively randomized to receive either the standard AcrySof MA30 intraocular lens (Alcon Laboratories, Ft Worth, Tex) (group 1) or an MA30 intraocular lens with a textured optic edge (group 2). Patients were seen at 1 month by an independent observer who was masked to treatment groups. A questionnaire on photic symptoms was completed, and attempts were made to elicit symptoms under mesopic and photopic conditions. RESULTS: At 1 month postoperatively, 20 (67%) of 30 patients in group 1 noticed symptoms compared with 4 (13%) of 30 patients in group 2 (P<.001). The mean duration of symptoms was 3.5 weeks in group 1 and 1 week in group 2 (P =.01). By provocative testing under photopic conditions, symptoms could be elicited in 26 patients (87%) in group 1 and 6 (20%) in group 2. No patients in either group were symptomatic at 3 months postoperatively. Under mesopic conditions, symptoms could be elicited in 27 patients (90%) in group 1 and 11 (37%) in group 2. There was no relationship between the incidence of symptoms and the degree of intraocular lens-rhexis contact. CONCLUSION: Photic phenomena can be significantly reduced by texturing the edge of a square-edged profile AcrySof intraocular lens.

Acrylates↗
PubMed2002

Failure of a discontinuous bend to prevent lens epithelial cell migration in vitro.

PURPOSE: To assess the effect of substrate geometry (discontinuous bend) on lens epithelial cell (LEC) growth in vitro. SETTING: Department of Ophthalmology, St. Thomas' Hospital, London, United Kingdom. METHODS: Culture wells with central depths of 0.4 mm, 1.0 mm, or 3.0 mm and a sharp square-edged profile (discontinuous bend) or a round-edged profile (continuous bend) were produced from a block of poly(methyl methacrylate). Freshly harvested bovine LECs were attached to the center of each well and cultured using standard techniques. Observations were made of whether LECs grew out of the wells and of the time required to do so. RESULTS: Lens epithelial cells migrated out of all the wells. There was no significant difference in the rate at which they migrated out of round-edged and square-edged wells. CONCLUSIONS: In vitro, a sharp discontinuous bend did not appear to induce contact inhibition of migrating LECs nor did it significantly hinder the rate at which LECs migrated. Therefore, a discontinuous bend in the lens capsule in isolation is unlikely to be responsible for the observed reduction in posterior capsule opacification associated with the use of square-edged IOLs.

Animals↗
PubMed2002

Mathematical modeling of the forces between an intraocular lens and the capsule.

PURPOSE: To model the pressure relationship between an intraocular lens (IOL) and the capsular bag. SETTING: Department of Physics, Kings' College, London University, London, United Kingdom. METHODS: A mathematical model was made of the forces between the capsule and IOL showing that the pressure related to the local radius of curvature of the IOL at any given point. The local radius of curvature for round-edged and square-edged IOLs was measured from electron micrographs of the IOL profiles, and the corresponding pressure profiles were calculated and compared. RESULTS: The pressure between an IOL and the capsular bag was proportional to the quotient of the tension in the capsule divided by the local radius of curvature of the IOL, with a constant of proportionality that depended on the coefficient of friction between the capsule and IOL. Measuring the local radius of curvature of the 2 IOL types suggested a pressure increase of at least 69% +/- 6% at the optic edge with the square-edged IOL. CONCLUSIONS: The mathematical model predicted that IOLs with square-edged optic profiles exerts higher pressure on the posterior capsule than IOLs with round-edged optic profiles. The higher pressure may form a physical barrier to lens epithelial cell migration onto the posterior capsule.

Humans↗