Posterior capsule opacification.

Biomedical Diagnostics. Edited by Tuan Vo-Dinh Edited by Tuan VoDinh. CRC Press 20142014. Pages 311–356. Print ISBN: 978-1-42008514-3. eBook ISBN:. Bjorn Kemper is a senior researcher at the Biomedical Technology Center of the Srirang Manohar is an associate professor of biomedical photonic imaging. This volume discusses biomedical photonics, spectroscopy and microscopy, the basic physical principles underlying the technology and its applications.

https://www.spiedigitallibrary.org/journals/journal-of-biomedical-optics/volume-9/issue-5/0000/Book-Review-Biomedical-Photonics-Handbook/10.1117/1.1776177.pdf

Biomedical Photonics Handbook

A systematic overview of the incidence of posterior capsule opacification

Objective: To better define the effectiveness and risks of modern cataract surgery Design: Meta-analysis (formal systematic identification, selection, review, and synthesis) of published literature Patients: Patients described in 90 studies published between 1979 and 1991 that addressed visual acuity (n=17 390 eyes) or complications (n=68 316 eyes) following standard extracapsular cataract extraction with posterior chamber intraocular lens implantation, phacoemulsification with posterior chamber intraocular lens implantation, or intracapsular cataract extraction with flexible anterior chamber intraocular lens implantation Main Outcome Measures: The proportion of eyes with postoperative Snellen visual acuity of 20/40 or better and the proportion of eyes with each of 18 complications Results: The pooled percentage of eyes (weighted by sample size) with postoperative visual acuity of 20/40 or better was 955% (95% confidence interval [CI], 951% to 959%) among eyes without preexisting ocular comorbidity and 897% (95% CI, 893% to 902%) for all eyes The pooled percentage of eyes experiencing complications (weighted by sample size and, when pertinent, by quality score of the individual studies but not adjusted for variation in duration of follow-up) ranged from 013% for endophthalmitis to 197% for posterior capsule opacification Pooled proportions of eyes with other complications were as follows: bullous keratopathy, 03%; intraocular lens malposition/dislocation, 11%; clinically apparent cystoid macular edema, 15%; and retinal detachment, 07% Pooled results for postoperative Snellen visual acuity and most complications were similar for surgery performed via phacoemulsification vs standard extracapsular cataract extraction, although comparisons of the outcomes between these procedures should be interpreted with caution Conclusions: The published literature indicates that modern cataract surgery yields excellent visual acuity and, although not free of complications, is a very safe procedure regardless of the extraction technique used

Synthesis of the Literature on Visual Acuity and Complications Following Cataract Extraction With Intraocular Lens Implantation

Capsule contraction syndrome is an exaggerated reduction in anterior capsulectomy and capsular bag diameter after extracapsular cataract surgery. While rarely seen with can-opener-style capsulectomies with anterior radial capsular tears, it is relatively frequent with capsulorhexis. It is particularly common in patients with pseudoexfoliation and in eyes with a history of moderately severe uveitis. Its effects, which include extreme reduction in the capsulectomy opening, malposition of the opening, reduction in equatorial capsular diameter, and displacement of the IOL, seem more exaggerated in small capsulorhexis openings and in the older patient. Neodymium:YAG laser radial anterior relaxing capsulotomies done within three weeks of cataract surgery reduce the sphincter effect of the contraction and lessen the chronic zonular-traction-related complications of the condition, which may include spontaneous IOL dislocation and retinal detachment.

Capsule contraction syndrome

Purpose To report the incidence, management, and prevention of patient reports of glare and streaks around a point source of light or a dark shadow in the temporal field of vision after acrylic intraocular lens (IOL) implantation. Setting A private practice. Methods Cases in which patients complained vigorously of dysphotopsia were catalogued prospectively during the implantation experience in 6668 consecutive eyes having surgery between January 1995 and June 1999. The techniques of topical-intracameral anesthesia, temporal clear corneal incisions, and phacoemulsification were used in all cases. Alternate IOL styles were selected for use from July 1999 to April 2000. Results Fourteen cases (0.2%) were identified. The complaints resolved in 1, were diminished in 1, and were tolerated without change in 7. Five eyes of 4 patients required IOL exchange with capsular bag placement of a poly(methyl methacrylate) (PMMA) or silicone lens for resolution of symptoms. Selecting alternate IOL styles reduced the incidence of dysphotopsia. Conclusions Glare and streaks from a point source of light represent positive photic expressions of dysphotopsia, and temporal dark shadows represent similar negative photic expressions. Both appear to be associated with shiny square-edge optics made of high-refractive-index acrylic polymer. Intraocular lenses of PMMA and silicone with rounded edges, along with square-edge acrylic IOLs with nonreflective edges, appear less likely to cause clinically significant pseudophakic dysphotopsia.

Positive and negative dysphotopsia in patients with acrylic intraocular lenses.

Six cases of capsular bag distension after capsulorhexis, endophacoemulsification, and posterior chamber intraocular lens (IOL) implantation are presented Five cases bad prominent posterior subcapsular cataracts preoperatively In three cases, the anterior chamber depths were shallower and the apparent refractive errors were more myopic than normal after surgery All six cases exhibited an apparent early complete sealing of the anterior capsular remnant against the anterior IOL optic In each case, the capsular bag contained moderate particulate debris and flare while the adjacent vitreous and anterior chambers were clear I suspect the particles are epithelial cell and cortical debris suspended in a fluid comprising lens epithelial protein, cellular breakdown products, balanced salt solution, and water Five cases have received no specific treatment In one case, a neodymium:YAG laser anterior capsulotomy allowed a forward egress of fluid from the distended capsular bag and a return to normal pseudophakic anatomy

Capsular bag distension after endophacoemulsification and posterior chamber intraocular lens implantation

Purpose To verify the safety and effectiveness of the new AcrySof Natural (Alcon Laboratories, Inc.) blue-light filtering intraocular lens (IOL), which was designed to achieve a light-transmission spectrum similar to that of the natural human crystalline lens. Setting Multicenter U.S. clinical trial. Methods In a prospective randomized patient-masked multicenter study, 150 patients received the AcrySof Natural IOL and 147 patients received the AcrySof single-piece IOL as a control. Patients with bilateral age-related cataracts who were willing and able to wait at least 30 days between cataract procedures and had verified normal preoperative color vision were eligible for the study. Standardized surgery included a 4.0 to 5.0 mm capsulorhexis and phacoemulsification. All lenses were inserted in the capsular bag, with verification of in-the-bag placement of both haptics. In all bilateral implantation cases, the same model IOL was used in each eye. Postoperatively, contrast sensitivity and color perception were measured up to 180 days and up to 1 year (for visual acuity) after implantation. Results No statistically significant differences were discovered between the 2 patient groups in visual acuity, contrast sensitivity evaluated under mesopic and photopic conditions, or the number of patients who passed the Farnsworth D-15 color perception test. There were no lens-related adverse events in either group. Conclusions The blue-light filtering AcrySof Natural IOL was equivalent to the conventional AcrySof lens in terms of postoperative visual performance. Additional long-term clinical studies should show whether the IOL actually provides the theoretical benefits to retinal health.

Clinical results of the blue-light filtering AcrySof Natural foldable acrylic intraocular lens

Ovoid intraocular lenses (IOLs) accounted for approximately 35% of the lenses implanted in 1991. Despite their popularity among surgeons, patient observations and complaints suggest that ovoid lenses are associated with undesired optical images postoperatively. A pilot clinical study was carried out to test that hypothesis. A multicentered investigation of 289 cases with well-centered IOLs determined that 45% of 168 patients with ovoid lenses observed unwanted optical phenomena at some time after surgery, whereas 17% of 121 patients with round IOLs had similar complaints. Based upon the preliminary clinical study a laboratory investigation was designed to assess optical performance differences between ovoid and round IOLs. One testing system used scatterometry and a second, ray tracing analysis. Both methods determined that the truncated, thickened edge of ovoid lenses was associated with significant light scattering, possibly accounting for the extraneous light images observed by some patients. The results of the clinical and laboratory investigations suggest that undesired optical images produced by ovoid IOLs are due to lens shape rather than to the reduced dimension of the optic.

Undesired light images associated with ovoid intraocular lenses

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