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Chapter 111 - Vitreoretinal surgery
- from Section 23 - Ophthalmic Surgery
- Edited by Michael F. Lubin, Emory University, Atlanta, Thomas F. Dodson, Emory University, Atlanta, Neil H. Winawer, Emory University, Atlanta
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- Book:
- Medical Management of the Surgical Patient
- Published online:
- 05 September 2013
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- 15 August 2013, pp 700-701
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Summary
Vitreoretinal surgical techniques are used to approach disorders of the posterior segment of the eye. Over the past 30 years, great strides have been made in the ability to safely and effectively operate in this segment. The spectrum of disorders menable to operative intervention has broadened significantly with the evolution of advanced, smaller-gauge microsurgical instruments, computer-controlled infusion and aspiration systems, endolaser probes, perfluorocarbon heavy liquid for manipulation of detached retinal tissue, implantable slow-release pharmacological devices, wide-angle optical viewing systems, and long-acting gases and silicone oil for intraocular tamponade. The treatment of intraocular tumors with radioactive episcleral plaques has also become well-characterized and “evidence-based” through large-scale, prospective, randomized clinical trial data. The advent and sophistication of the pars plana approach with microsurgical vitrectomy instrumentation has allowed for the repair of most simple and complex primary and recurrent retinal detachments. The pars plana is the section of the eye located approximately at the junction of the iris and the sclera and is a safe place to insert intraocular instruments without damage to internal structures. However, in certain cases of primary retinal detachment, the most appropriate treatment remains scleral buckling surgery, as has been performed for over 60 years.
Scleral buckling surgery involves the placement of a strip of silicone around the outside of the globe to cause a slight indentation or buckle of the eye wall and support the intraocular retinal breaks and vitreous base. The procedure is effective because the external support helps close the causative retinal tear inside the eye. The retinal tear is repaired by a combination of support from the buckle and the formation of a chorioretinal scar induced by a thermal modality such as cryotherapy (freezing) or laser (heating). The usual procedure for addressing complex retinal detachments with very large or posteriorly located retinal tears, significant retinal scarring, vitreous hemorrhage, or severe cataract formation is to combine scleral buckle surgery with the more advanced intraocular vitrectomy techniques.
Chapter 115 - Enucleation, evisceration, and exenteration
- from Section 23 - Ophthalmic Surgery
- Edited by Michael F. Lubin, Emory University, Atlanta, Thomas F. Dodson, Emory University, Atlanta, Neil H. Winawer, Emory University, Atlanta
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- Book:
- Medical Management of the Surgical Patient
- Published online:
- 05 September 2013
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- 15 August 2013, pp 708-710
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Summary
Removal of an eye or the contents of an orbit may be indicated when the eye is affected by neoplasia or a severe infectious process, or when an end-stage ocular disease in a blind eye causes pain. These ophthalmic interventions are usually classified as:
Enucleation: the removal of the entire globe, including the sclera, intraocular contents, and the cornea. The stump of the optic nerve as well as the extraocular muscles are left behind.
Evisceration: the removal of intraocular contents including the lens, uvea, retina, vitreous humor, and in some cases the cornea. Only the sclera and extraocular muscles remain intact.
Exenteration: the removal of the globe and all of the orbital contents. This procedure may include removal of selective sections of orbital bone.
Following enucleations and eviscerations, an orbital implant is used to replace the globe and restore the lost orbital volume. The implant or sphere serves to maintain the structure of the orbit and to provide motility to the overlying prosthesis. For children, it additionally serves to maintain more normal growth of the surrounding orbital bones. In cases of exenteration, an osseointegrated prosthesis may be attached within the orbit, secured with metal support elements or magnets that are attached to bone.
Chapter 108 - General considerations in ophthalmic surgery
- from Section 23 - Ophthalmic Surgery
- Edited by Michael F. Lubin, Emory University, Atlanta, Thomas F. Dodson, Emory University, Atlanta, Neil H. Winawer, Emory University, Atlanta
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- Book:
- Medical Management of the Surgical Patient
- Published online:
- 05 September 2013
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- 15 August 2013, pp 693-695
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Summary
A vast array of surgical interventions may be performed in the treatment of ocular and periorbital disease. Because of the high technical difficulty, the subspecialist often performs a significant portion of the ophthalmic surgeries. Most procedures in ophthalmology involve microsurgery and are usually limited to the eye and orbit. Thus, typically there is minimal risk to other organs. Ophthalmic surgery offers a high probability of success, with a major positive impact on quality of life. Nevertheless, many patients with eye pathology are elderly, and some have significant systemic illness. Therefore, the risk of elective intervention must be balanced against the expected benefits, and appropriate counseling should be performed prior to surgery. Optimizing the management of medical problems preoperatively can make the surgery safer and minimize patient discomfort.
Anesthesia
The large majority of ophthalmic interventions can be performed under local anesthesia with intravenous sedation. In some cases, even topical anesthetics are sufficient. But there are ophthalmic surgeries that require general anesthesia, such as those that involve significant extraocular manipulation, for which the local anesthetic may not be as effective, or those that may be prolonged, as is often the case in many vitreoretinal and orbital procedures. Some periorbital or facial cosmetic interventions often necessitate general anesthesia as well. General anesthesia is also indicated in younger patients and those who may not be cooperative enough to remain motionless during surgery. In addition, general anesthetics are required in trauma cases with significant ocular laceration, where administration of local anesthetics may raise intraorbital pressure, necessitating subsequent extrusion of intraocular contents. Several choices exist in the route of administration of local ophthalmic anesthesia for intraocular surgery. The most widely used approach is injection of 3–7 mL of a mixture of lidocaine 2% and marcaine 0.75% through a retrobulbar approach using a blunted needle (Atkinson needle). This is often performed with a regional seventh nerve block to paralyze eyelid closure. The risks of local ophthalmic anesthesia are remote, but they may be significant. They include local damage through retrobulbar hemorrhage, extraocular muscle damage, and penetration of the globe or optic nerve. Systemic exposure to the injected medication through intravascular or subarachnoid injection of the anesthetic has been known to cause hypertension, seizures, apnea, or even death.
102 - Corneal transplantation
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- By C. Diane Song, Emory University, School of Medicine, Atlanta, GA, Enrique Garcia-Valenzuela, Emory University, School of Medicine, Atlanta, GA, G. Baker Hubbard III, Emory University, School of Medicine, Atlanta, GA, Thomas M. Aaberg, Sr., Emory University, School of Medicine, Atlanta, GA
- Edited by Michael F. Lubin, Emory University, Atlanta, Robert B. Smith, Emory University, Atlanta, Thomas F. Dodson, Emory University, Atlanta, Nathan O. Spell, Emory University, Atlanta, H. Kenneth Walker, Emory University, Atlanta
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- Book:
- Medical Management of the Surgical Patient
- Published online:
- 12 January 2010
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- 10 August 2006, pp 700-701
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Summary
Corneal transplant, also known as penetrating keratoplasty, has a 90% success rate as defined by clear grafts in 1 year. The primary indication for the procedure is a hazy or opaque cornea causing decrease in vision. The etiologies of corneal opacities include congenital defects, hereditary dystrophies, infection, and trauma. Occasionally, corneal transplants are performed simultaneously with cataract surgery, intraocular lens exchange, or with posterior segment surgery, depending on other conditions affecting vision. The procedure is not as common as lamellar keratoplasty, in which only the anterior surface of the cornea is grafted, leaving the posterior surface intact.
For most patients, the operation is performed on an outpatient basis under local anesthesia with monitored anesthesia care. Under special circumstances, a patient may require general anesthesia and overnight stay in the hospital. Depending on whether or not other intraocular surgeries are performed at the same time, the operation lasts between one half to two hours and involves removing the patient's hazy cornea and replacing it with a clear donor cornea that is sewn in place with nylon sutures. It is performed under an operating microscope and requires the patient to lie still. When the operation is complete, the patient is given topical medications and the eye should be patched overnight. Blood loss is minimal to none during the procedure.
Usual postoperative course
Expected postoperative hospital stay
Most patients go home on the day of surgery.
Operative mortality
Extremely low and generally associated with the anesthetic used.
103 - Vitreoretinal surgery
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- By G. Baker Hubbard III, Emory University, School of Medicine, Atlanta, GA, Enrique Garcia-Valenzuela, Emory University, School of Medicine, Atlanta, GA, Thomas M. Aaberg, Sr., Emory University, School of Medicine, Atlanta, GA
- Edited by Michael F. Lubin, Emory University, Atlanta, Robert B. Smith, Emory University, Atlanta, Thomas F. Dodson, Emory University, Atlanta, Nathan O. Spell, Emory University, Atlanta, H. Kenneth Walker, Emory University, Atlanta
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- Book:
- Medical Management of the Surgical Patient
- Published online:
- 12 January 2010
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- 10 August 2006, pp 702-703
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Summary
Vitreoretinal surgical techniques are used to address disorders of the posterior segment of the eye. Great strides have been made in the ability to safely and effectively operate in the posterior segment over the last 20 years. With the evolution of advanced microsurgical instruments, computerized infusion and aspiration systems, endolaser probes, perfluorocarbon heavy liquid for manipulation of detached retinal tissue, implantable slow-release pharmacological devices, wide angle optical viewing systems, and long-acting gases and silicone oil for intraocular tamponade, the spectrum of disorders which are amenable to operative intervention has broadened significantly. The treatment of intraocular tumors with radioactive episcleral plaques has also become well established in recent years. However, in many cases of primary retinal detachment, the most appropriate treatment remains the standard scleral buckling operation that has been performed for over 60 years.
The scleral buckling operation consists of placing a strip of silicone around the outside of the globe to cause a slight indentation or buckle of the eye wall. The buckle achieves its purpose because the indentation helps close the causative retinal tear inside the eye. A combination of support from the buckle and chorioretinal scarring induced by treating the tear with cryotherapy maintain closure of the retinal tear. Complex retinal detachments with very large or posteriorly located retinal tears, significant retinal scarring, vitreous hemorrhage, or severe cataract formation are usually approached with a combination of scleral buckle and the more advanced intraocular vitrectomy techniques listed above.
100 - General considerations in ophthalmic surgery
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- By Enrique Garcia-Valenzuela, Emory University, School of Medicine, Atlanta, GA, G. Baker Hubbard III, Emory University, School of Medicine, Atlanta, GA, Thomas M. Aaberg, Sr., Emory University, School of Medicine, Atlanta, GA
- Edited by Michael F. Lubin, Emory University, Atlanta, Robert B. Smith, Emory University, Atlanta, Thomas F. Dodson, Emory University, Atlanta, Nathan O. Spell, Emory University, Atlanta, H. Kenneth Walker, Emory University, Atlanta
-
- Book:
- Medical Management of the Surgical Patient
- Published online:
- 12 January 2010
- Print publication:
- 10 August 2006, pp 693-697
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Summary
Numerous types of surgical intervention can be performed in the treatment of diseases of the eye and its adnexa. Owing to the great degree of technical skill required to execute these interventions, subspecialists perform a significant portion of ophthalmic surgeries. Microsurgery is involved in all procedures and most of the operations are limited to intervention into the eye and orbit with minimal risk to other organs. Ophthalmic surgery offers a high probability of success with a major positive impact on the quality of life. However, many patients with eye pathology are elderly and some have significant systemic illness, so the risk of elective intervention must be balanced against expected benefits. Optimal preoperative management of medical problems can make surgery safer and minimize patient discomfort.
Anesthesia
The large majority of ophthalmic interventions can be performed under local anesthesia with intravenous sedation. In some cases, even topical anesthetics are sufficient. Ophthalmic surgeries that require general anesthesia are those that involve significant extraocular manipulation in regions where a local anesthetic is not effective, and those that are prolonged as occurs in many vitreoretinal and orbital procedures as well as some cosmetic operations. General anesthesia is also indicated in younger patients and individuals who may not remain motionless during surgery and trauma cases with significant ocular laceration where administration of local anesthetics may raise intraorbital pressure with consequent extrusion of intraocular contents.
Several choices exist in the route of administration of local ophthalmic anesthesia for intraocular surgery.
104 - Glaucoma surgery
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- By Anastasios P. Costarides, Emory University, School of Medicine, Atlanta, GA, G. Baker Hubbard III, Emory University, School of Medicine, Atlanta, GA, Enrique Garcia-Valenzuela, Emory University, School of Medicine, Atlanta, GA, Thomas M. Aaberg, Sr., Emory University, School of Medicine, Atlanta, GA
- Edited by Michael F. Lubin, Emory University, Atlanta, Robert B. Smith, Emory University, Atlanta, Thomas F. Dodson, Emory University, Atlanta, Nathan O. Spell, Emory University, Atlanta, H. Kenneth Walker, Emory University, Atlanta
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- Book:
- Medical Management of the Surgical Patient
- Published online:
- 12 January 2010
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- 10 August 2006, pp 704-705
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Summary
Multiple ocular conditions can lead to the development of glaucoma, which is the most common optic neuropathy. All therapeutic interventions are directed towards lowering the condition's greatest risk factor, intraocular pressure.
Typically, therapy is instituted in an ascending fashion, with topical medical therapy being the first and simplest option. Medications include topical beta adrenergic blockers, prostaglandin analogs, carbonic anhydrase inhibitors, alpha adrenergic agonists, and miotics; these agents, used alone or in combination, are often sufficient for control of intraocular pressure. In cases of open angle glaucoma requiring greater management of intraocular pressure, laser trabeculoplasty, an outpatient procedure, is used in conjunction with medications. For angle closure glaucoma, outpatient laser iridotomy is applied to relieve the pupillary block mechanism.
Incisional intraocular surgery is the most frequent choice when medical and outpatient laser procedures fail to diminish intraocular pressure, with trabeculectomy and aqueous tube shunt placement being the most commonly used procedures. Both approaches lower intraocular pressure by allowing aqueous humor to leave the anterior chamber and collect in the subconjunctival space. When other interventions have either failed or are unfeasible, such cyclodestructive procedures as laser ablation or cryoablation of the ciliary processes may be done. Incisional surgery is done in an operating room, usually on an outpatient basis; cyclodestructive operations are performed in a clinic setting; and local anesthesia is standard for both methods.
Usual postoperative course
Expected postoperative hospital stay
Glaucoma surgery usually does not require hospitalization, though monocular patients undergoing incisional surgery may be hospitalized.
106 - Eye muscle surgery
- Edited by Michael F. Lubin, Emory University, Atlanta, Robert B. Smith, Emory University, Atlanta, Thomas F. Dodson, Emory University, Atlanta, Nathan O. Spell, Emory University, Atlanta, H. Kenneth Walker, Emory University, Atlanta
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- Book:
- Medical Management of the Surgical Patient
- Published online:
- 12 January 2010
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- 10 August 2006, pp 708-709
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Summary
Eye muscle surgery is performed to correct strabismus, which is any horizontal, vertical, or torsional misalignment of the eyes that affects both children and adults. The disease can be congenital, acquired, restrictive, or paralytic. The purpose of surgery is to restore the eyes to their normal, anatomical position; to maximize the potential for binocularity; and, in some cases, to eliminate diplopia. Either one or multiple muscles may be involved in the operation and bilateral procedures are common. In cooperative children and adults, a postoperative adjustment of the muscle position may be performed once the effects of anesthesia have dissipated.
Strabismus surgery is most often performed under general anesthesia, though local anesthesia and even topical anesthesia can be used in adults.
Usual postoperative course
Expected postoperative hospital stay
Most strabismus surgery is performed on an outpatient basis. Hospitalization is unusual.
Operative mortality
Related to anesthesia. The incidence of malignant hyperthermia may be slightly higher in strabismus patients than in the general population.
Special monitoring required
None necessary.
Patient activity and positioning
For 2 weeks, patients are advised to avoid swimming and other activities that may introduce contaminated material into their eyes. Young children should be properly supervised and discouraged from rubbing their eyes. Dressings are usually unnecessary.
Alimentation
Oral intake should be resumed gradually, since nausea and vomiting are common after strabismus surgery, especially in children.
Antibiotic coverage
Topical antibiotic or antibiotic/steroid combination drops may be used optionally.
107 - Enucleation, evisceration and exenteration
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- By Enrique Garcia-Valenzuela, Emory University, School of Medicine, Atlanta, GA, G. Baker Hubbard III, Emory University, School of Medicine, Atlanta, GA, Thomas M. Aaberg, Sr., Emory University, School of Medicine, Atlanta, GA
- Edited by Michael F. Lubin, Emory University, Atlanta, Robert B. Smith, Emory University, Atlanta, Thomas F. Dodson, Emory University, Atlanta, Nathan O. Spell, Emory University, Atlanta, H. Kenneth Walker, Emory University, Atlanta
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- Book:
- Medical Management of the Surgical Patient
- Published online:
- 12 January 2010
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- 10 August 2006, pp 710-712
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Summary
Ophthalmic surgeons may want to remove ocular structures when they are affected by neoplasia, when they are distressed by a severe infectious process, or when an end-stage ocular disease is causing pain. There are three types of ophthalmic intervention:
Enucleation
Removal of the entire eyeball, including sclera and cornea, leaving a stump of the optic nerve and the extraocular muscles. An intraorbital prosthesis is usually implanted.
Evisceration
Removal of all intraocular structures, leaving only sclera and sometimes cornea. An ocular prosthesis is usually implanted.
Exenteration
Removal of the eyeball and the orbital contents which may include removal of orbital bone.
Enucleation is the most frequently performed surgical approach for elimination of intraocular structures. When ocular disease has rendered an eye completely blind (incapable of perceiving the brightest light), any possibility of visual recovery is minimal. Frequently, such severity of pathology makes an eye painful and cosmetically unacceptable in spite of medical treatment. Although there are several procedural choices, the most widely accepted surgery is removal of the eye or enucleation because of its long-term outcome and safety. A frequent scenario where enucleation is recommended is after severe ocular trauma. A blind eye should be enucleated within 2 weeks after trauma to prevent sympathetic ophthalmia, a rare complication where the exposed uveal tissue leads to autoimmune attack of the contralateral healthy eye. Other indications for enucleation include infectious endophthalmitis, end-stage glaucoma, and malignant intraocular tumors.
105 - Refractive surgery
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- By C. Diane Song, Emory University, School of Medicine, Atlanta, GA, Enrique Garcia-Valenzuela, Emory University, School of Medicine, Atlanta, GA, G. Baker Hubbard III, Emory University, School of Medicine, Atlanta, GA, Thomas M. Aaberg, Sr., Emory University, School of Medicine, Atlanta, GA
- Edited by Michael F. Lubin, Emory University, Atlanta, Robert B. Smith, Emory University, Atlanta, Thomas F. Dodson, Emory University, Atlanta, Nathan O. Spell, Emory University, Atlanta, H. Kenneth Walker, Emory University, Atlanta
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- Book:
- Medical Management of the Surgical Patient
- Published online:
- 12 January 2010
- Print publication:
- 10 August 2006, pp 706-707
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Summary
Done to reduce dependence on glasses or contact lenses, refractive surgery involves reshaping the cornea with incisions, heat, or laser to decrease myopia, astigmatism, or hyperopia. Presently, the most frequently performed refractive surgical procedure is laser-assisted in situ keratomileusis (LASIK).
LASIK can correct refractive error within a wide range. To deduce whether LASIK is a good option for a patient, a thorough preoperative eye exam is necessary. Indications may include intolerance to contact lenses, improved conditions for job-related or hobby-related activities, or a desire to lessen reliance on glasses and contact lenses.
Performed in an outpatient setting with topical anesthesia, the operation usually lasts about 15 minutes with the patient experiencing minimal discomfort. Both eyes may be operated on the same day. After it is cut, the thin corneal flap is lifted and reflected to allow the laser to reshape the cornea. The laser is programmed with the patient's refractive error; once that refractive error is corrected, the corneal flap is realigned into place.
Usual postoperative course
Expected postoperative hospital stay
Most surgeries are performed in a surgicenter on an outpatient basis.
Special monitoring required
The patient's eyes are generally not patched, though sunglasses may be necessary if there is sensitivity to light. Discomfort is minimal postoperatively.
Patient activity and positioning
Most patients will be able to see well enough on the first postoperative day to return to regular activity, though they require reading glasses for near vision if they are in the presbyopic age range.
101 - Cataract surgery
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- By G. Baker Hubbard III, Emory University, School of Medicine, Atlanta, GA, Enrique Garcia-Valenzuela, Emory University, School of Medicine, Atlanta, GA, Thomas M. Aaberg, Sr., Emory University, School of Medicine, Atlanta, GA
- Edited by Michael F. Lubin, Emory University, Atlanta, Robert B. Smith, Emory University, Atlanta, Thomas F. Dodson, Emory University, Atlanta, Nathan O. Spell, Emory University, Atlanta, H. Kenneth Walker, Emory University, Atlanta
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- Book:
- Medical Management of the Surgical Patient
- Published online:
- 12 January 2010
- Print publication:
- 10 August 2006, pp 698-699
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Summary
Cataracts are characterized by opacity of the crystalline lens of the eye and are the primary cause of preventable blindness in the world. They may be congenital or age related; secondary to exposure to drugs, toxins, or radiation; or the product of various metabolic diseases. Visually significant cataracts are a major public health issue and are found in 50% of persons 65 to 74 years of age and 70% of persons 75 years of age or older.
Modern cataract extraction with placement of an intraocular lens (IOL) is a highly effective and efficient operation to restore visual acuity and contrast sensitivity in patients with severe cataracts. Presently, the operation has evolved to the point where it involves constructing a small (2.5–3.5 mm) wound at the edge of the cornea. The incision is carefully shelved to minimize leakage through the wound, viscoelastic material is injected into the anterior chamber to protect the cornea, and the anterior capsule of the lens is removed. An ultrasound probe (phacoemulsification tip) is then inserted into the anterior chamber and used to fragment and remove the cataractous lens, though the capsule of the lens is left intact except for a small opening in the anterior portion through which the phaco tip had been inserted. An IOL with appropriate focusing power to neutralize any refractive error is chosen based on the size and corneal curvature of the patient's eye.
Non-Standard Fickian Self-Diffusion of Isotopically Pure Boron Observed by Neutron Reflectometry and Depth Profiling
- Shenda M. Baker, K. Wu, G. S. Smith, K. M. Hubbard, M. Nastasi, R. G. Downing, G. P. Lamaze
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- Journal:
- MRS Online Proceedings Library Archive / Volume 376 / 1994
- Published online by Cambridge University Press:
- 22 February 2011, 209
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- 1994
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Neutron reflectometry (NR) studies1 of thin films of amorphous 11B/l0B on silicon indicate that a non-standard form of Fickian diffusion occurs across the boron interface upon annealing. In order to verify this observation, the samples were examined by neutron depth profiling (NDP). Comparison of the results from models of a step function, standard Fickian diffusion and Fickian diffusion with a fixed composition at the interface were made and compared to the previous NR results. The diffusion constant resulting from the non-standard Fickian model for the NDP data differs slightly from that obtained from the commonly used Fickian diffusion model and is not inconsistent with the NR results. This finding suggests that more information regarding diffusion at interfaces can be gained from these higher resolution neutron scattering techniques.