Cataract Extraction :: instrumentation
J AAPOS. 2012 Apr ;16 (2):167 22662338
Southampton University Hospitals NHS Trust.
Most cited papers:
Light-induced maculopathy from the operating microscope in extracapsular cataract extraction and intraocular lens implantation.
A characteristic macular lesion has been noted in six patients who underwent extracapsular cataract extraction with posterior chamber lens implantation. The lesion appeared similar to that which other investigators have produced in monkeys as a response to the coaxial illumination of the operating microscope. On the first or second postoperative day, the lesion appeared as an oval area of mild yellow-white discoloration of the retina; gradually it developed mottled pigmentation over the next few weeks. The pigmentary changes were often subtle, but fluorescein angiography revealed a characteristic sharply circumscribed lesion. In most of our patients the lesion was just above or below the foveola, so that central vision returned to normal, but a paracentral scotoma was present. These findings should encourage the clinician to heed the warnings of those laboratory studies which have shown the phototoxic potential of the operation microscope's unfiltered coaxial illumination and force us to re-examine our filters and operating techniques.
"Equator ring" for maintenance of the completely circular contour of the capsular bag equator after cataract removal.
Hara Eye Hospital, Utsunomiya, Japan.
We designed an "equator ring," a flexible silicone rod with a groove on its inner surface, to maintain the circular contour of the capsular bag equator after cataract removal. After cataract extraction, the ring is inserted in the bag through a 5.0-mm circular capsulorhexis or 4.5-mm linear "dumbbell" opening. Then a conventional posterior chamber intraocular lens (PC-IOL) is inserted, with the IOL loops in the groove. The ring not only allows complete maintenance of the circular contour of the capsular bag equator for most conventional PC-IOLs, but also may prevent invasion of metamorphosed lens epithelial cells into the posterior capsule.
Department of Ophthalmology, School of Medicine, Keio University, Tokyo, Japan.
We designed four prototypes of a capsular bag supporting ring for supporting and preserving postoperative integrity of the capsular bag, independently of the intraocular lens (IOL) implanted following continuous curvilinear capsulorhexis. An open poly(methyl methacrylate) ring, inserted experimentally in cadaver eyes through a 3.5 mm incision, adjusted well to various capsular bag sizes and could be implanted with common IOL types. Although some capsular shrinkage occurred in vitro, the roundness of the capsular bag equator was preserved, suggesting that the ring may help maintain postoperative capsular bag integrity.
Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.
Oxygen free radical formation by conventional phacoemulsification devices has been postulated as a possible mechanism of corneal endothelial damage during surgery. To test this hypothesis, phacoemulsification probe-induced free radical production was visualized using a single photon-counting camera and an O(2-)-sensitive luciferin derivative, 2-methyl-6-[p-methoxyphenyl-3,7-dihydroimidazo [1,2-a]pyrazin-3-one (MCLA), which allows the visualization of spatial and temporal alterations in free radical production. Within 1 min after starting ultrasound emission, MCLA-dependent chemiluminescence was increased significantly, the intensity of which was maximal at the tip of the probe and tapered along a gradient toward distal portions. The chemiluminescence was suppressed significantly by adding either superoxide dismutase (300 U/ml) or sodium azide (20 mmol/l). By adding deuterium to the medium, MCLA-dependent chemiluminescence significantly increased, suggesting the involvement of singlet oxygen in the reaction.
Hara Eye Hospital, Utsunomiya, Japan.
OBJECTIVE To determine the efficacy of the equator ring in maintaining the circular contour of the capsule bag equator and transparency of the posterior capsule after crystalline lens extraction in 12 rabbit eyes. METHODS After phacoemulsification through a 5-mm window made by continuous circular capsulorrhexis in the central anterior capsule, a flexible silicone ring (outer diameter, 11.0 mm; width, 1.5 mm; and thickness, 1.5 mm) was implanted in the capsule in seven rabbit eyes. A 13.0-mm Sinskey-style posterior chamber intraocular lens was then implanted inside the ring. Three other eyes received only equator rings, and two others received only intraocular lenses. Eyes were followed up for 3.5 +/- 1.4 months (mean +/- SD) before enucleation and evaluation by stereomicroscopy; they then underwent light microscopic examination. RESULTS The two eyes that received only the intraocular lens had equatorial distortion and severe posterior capsule opacification. In nine (90%) of the 10 eyes that were implanted with the rings, the circular contour of the equator was preserved, and seven (70%) of these 10 eyes had transparent posterior capsules. CONCLUSION Implantation of the equator ring effectively maintained the circular contour of the capsule bag equator and inhibited cells at the bag equator from proliferating toward the center of the posterior capsule in the rabbit.
The authors analyzed 310 cataract operations that were randomly distributed between two operating rooms, each containing a microscope with different light intensities. The light intensity of one microscope was almost threefold greater than the other. One hundred seventy-seven patients were excluded from this study because of medical or ocular problems that might affect visual acuity. The remaining 133 patients are the subjects of this paper. Seventy-one were operated upon under high intensity light, and 62 were subjected to lower illumination in the operating room. Visual acuity after operation was correlated with type of microscope, age, sex, method of cataract extraction, and use of intraocular lenses. Reduced visual acuity (20/40 or worse) was consistently more common with high intensity light and with increasing age. Further investigation is recommended to establish the cause of this reduced acuity.
Tel Aviv University, Goldschleger Eye Institute, Ein Tal Eye Center, Israel.
BACKGROUND: Manual ECCE has proved to be safe surgery compatible with small incision, no stitches, possible topical anesthesia, very cost effective and quick rehabilitation. The technique has a learning curve and needs experience."Mini-nuc" stands for mini nucleus. This surgery can be achieved only if performed under positive intraocular pressure (IOP). METHODS: A BSS bottle is connected to the eye by an anterior chamber maintainer (ACM). The height of the BSS bottle controls the IOP during the surgery. Controlled IOP is a principle suggested for all kinds of cataract surgery. It creates continuous flow which washes out of the eye cortex debris, blood, pigment, etc. The BSS contains antibiotics and adrenalin, it creates low turbulence due to the small amount of BSS used per case, 30-50 cc. A round capsulorhexis is essential. A special way of hydrodissection creates a very small hard core nucleus delivered to the anterior chamber and is extracted out through a sclero-corneal tunnel using a glide introduced under the nucleus to guide the nucleus out. RESULTS: Positive IOP during all stages of surgery creates the best operative conditions for controlled surgery throughout all manipulations. This technique is a very cost effective system and at the same time provides a high quality procedure.
University of Toronto, Toronto, Canada. firstname.lastname@example.org
PURPOSE To present techniques and results of surgical repositioning of subluxed and dislocated capsular tension rings (CTRs). DESIGN Retrospective interventional case series. PARTICIPANTS Eleven patients with a previously implanted CTR in-the-bag for zonular weakness who presented with CTR-intraocular lens (IOL)-capsular bag decentration who underwent surgical repositioning. METHODS Data from 11 patients who underwent surgical repositioning were evaluated retrospectively for underlying diagnosis, interval between initial surgery and decentration, surgical technique, clinical results, and complications. MAIN OUTCOME MEASURES Capsular tension ring-IOL-capsular bag centration, final best-corrected visual acuity (BCVA), and surgical complications. RESULTS Of the 11 patients with CTR decentration, 3 had it early in the postoperative period, and 8 had it late. Mean (+/- standard deviation) durations from cataract extraction and CTR implantation to surgical repositioning were 6.1+/-7.9 months for those with decentration early and 49.6+/-15.3 months for late decentrations (overall range, 0.7-74.7). Of the 11 patients, 7 had pseudoexfoliation, and 4 of the 7 had associated glaucoma. Nine patients had subluxation of the CTR-IOL-capsular bag complex, which was managed by an anterior segment approach. A pars plana vitrectomy and levitation of the CTR was required in 2 patients due to complete dislocation of the CTR into the posterior vitreous. Surgical techniques for repositioning included single, double, or 3-point scleral suture loop fixation of the CTR through the capsular bag complex (8 eyes); use of the capsular tension segment (CTS) placed within the capsular bag for scleral suture fixation (2); or iris suture fixation of the IOL haptics (1). All patients achieved successful anatomical repositioning of the CTR-IOL-capsular bag complex. Mean preoperative BCVA improved from 20/100 to 20/40 postoperatively. After repositioning surgery, BCVA improved in 7 patients, was maintained in 2, and worsened in 2 (due to advanced glaucoma). CONCLUSION Postoperative CTR subluxation or dislocation is a risk for patients with severe or progressive zonulopathy. Decentrations may be effectively managed with scleral suture fixation of the CTR through the capsular bag or the use of the CTS.
Colleen DesRosiers, Marc S Mendonca, Craig Tyree, Vadim Moskvin, Morris Bank, Leo Massaro, Robert M Bigsby, Andrea Caperall-Grant, Shailaja Valluri, Joseph R Dynlacht, Robert Timmerman
Departments of Radiation Oncology, Indiana University Schools of Medicine and Dentistry, Indianapolis, IN 46202, USA. email@example.com
For most basic radiobiological research applications involving irradiation of small animals, it is difficult to achieve the same high precision dose distribution realized with human radiotherapy. The precision for irradiations performed with standard radiotherapy equipment is +/-2 mm in each dimension, and is adequate for most human treatment applications. For small animals such as rodents, whose organs and tissue structures may be an order of magnitude smaller than those of humans, the corresponding precision required is closer to +/-0.2 mm, if comparisons or extrapolations are to be made to human data. The Leksell Gamma Knife is a high precision radiosurgery irradiator, with precision in each dimension not exceeding 0.5 mm, and overall precision of 0.7 mm. It has recently been utilized to treat ocular melanoma and induce targeted lesions in the brains of small animals. This paper describes the dosimetry and a technique for performing irradiation of a single rat eye and lens with the Gamma Knife while allowing the contralateral eye and lens of the same rat to serve as the "control". The dosimetry was performed with a phantom in vitro utilizing a pinpoint ion chamber and thermoluminescent dosimeters, and verified by Monte Carlo simulations. We found that the contralateral eye received less than 5% of the administered dose for a 15 Gy exposure to the targeted eye. In addition, after 15 Gy irradiation 15 out of 16 animals developed cataracts in the irradiated target eyes, while 0 out of 16 contralateral eyes developed cataracts over a 6-month period of observation. Experiments at 5 and 10 Gy also confirmed the lack of cataractogenesis in the contralateral eye. Our results validate the use of the Gamma Knife for cataract studies in rodents, and confirmed the precision and utility of the instrument as a small animal irradiator for translational radiobiology experiments.