Biomedical subjects
Publications and source records attributed to C L Schepens.
A thin, conical diathermy electrode with a smooth-surfaced bent, insulated tip was designed for use in narrow incisions, corners, and angles of dissected scleral flaps. It permits precise delivery of focal diathermy and avoids undesirable parafocal tissue damage. This electrode is especially valuable for preventing uveal bleeding from a sclerochoroidal incision over the pars plana ciliaris and for treating small posterior retinal breaks.
Two hundred consecutive closed vitrectomies through the pars plana were observed for at least five years after operation to determine the results and analyze the complications. Vitrectomy was performed to remove vitreous opacities in 56.5% of the eyes (group 1), as a preliminary procedure in the course of retinal reattachment in 42% (group 2), and to reconstruct the anterior segment in 1.5% (group 3). Of the group 1 eyes for which adequate follow-up data were available, visual acuity improved notably in 64.2% showed no change in 11.3%, and deteriorated in 24.5%. The respective percentages for the other groups were as follows: 23.3%, 19.2%, and 57.5% for group 2; and 0%, +66.7%, and +33.3% for group 3. The most common complication during operation was bleeding in the vitreous, especially in diabetic patients; retinal break, lens injury, and vitreous-base avulsion followed in frequency. Postoperative bleeding occurred in 23% of eyes but usually resolved spontaneously and required no further surgery. There was postoperative glaucoma in 20% of the eyes. Corneal decompensation (15% of all cases) and rubeosis iridis (also 15%) had a propensity to occur in diabetic patients. Multiple procedures seemed to predispose eyes undergoing vitrectomy to rubeosis. Fibrous ingrowth into the vitreous through the sclerotomy was seen in five eyes and was associated with retinal detachment in one.
We controlled the development of epithelial edema of the cornea during closed vitreoretinal surgery even when the technique required continuous use of a contact lens by gentle debridement of only the shaggy, edematous superficial layer of wing cells, using an olive-tip irrigator. This technique may avoid the necessity of completely removing the epithelium and the attendant postoperative complications.
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We developed a method for testing visual acuity using a general-purpose microcomputer which displays visual acuity targets on a television monitor, controls a staircase psychophysical testing procedure, and provides a printed record of mean visual acuity and standard deviation. This automated procedure can be used to increase the precision of clinical visual acuity testing and to determine if changes in a patient's visual acuity are statistically significant.
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Retinal functions were studied in 7 patients with snowflake degeneration and correlated with fundus appearance. Despite the presence of vitreous turbidity, scotomatic glare sensitivity was slightly elevated in only one case. Retinal functions were affected more extensively in the late stages of the disease; however, abnormal retinal functions were also detected in some patients who showed only slight fundus changes on ophthalmoscopic examination. Kinetic perimetry showed peripheral defects which were more pronounced in the upper field. Flicker perimetry revealed abnormalities that kinetic perimetry could not detect. Dark-adaptation tests showed elevated rod thresholds except during the early stage of the disease. In all patients, the scotopic b-wave of the electroretinogram elicited by dim white light was low in amplitude. The photopic b-wave and the photopic flicker responses showed decreased amplitudes in some patients. The scotopic b-wave, normally recorded as a second positive peak when deep red light is used, almost disappeared, leaving only a small, single positive peak, photopic in nature, in the late stages. However, no patient had a nonrecordable electroretinogram. The electro-oculographic light peak/dark trough ratio was abnormal in only a few patients. These results indicate that in snowflake degeneration, functional abnormalities of the retina are milder than those in other progressive primary retinal degenerations typically represented by retinitis pigmentosa.
Hyaluronic acid vitreous substitute (HYVISC) was used during 347 operations performed on 294 eyes of 286 patients. It was injected intraocularly in 266 operations (73 scleral bucklings, 175 open-sky vitrectomies, among others) on eyes with complex retinal detachments that were considered inoperable by ordinary surgical techniques. During 81 closed vitrectomies, it was applied extraocularly between the surgical contact lens and the cornea. Hyaluronic acid was found to be well tolerated by human eyes. In eyes that had been given a poor prognosis, scleral buckling with hyaluronic acid tamponade produced reattachment in 16% of the eyes; open-sky vitrectomy, scleral buckling, and hyaluronic acid salvaged 18%. It also appeared helpful in the preservation of corneal epithelial integrity and clarity during closed vitrectomy.
Description of Grieshaber nibbler for closed vitreous surgery: tip diameter is 1.6 mm, cutting is by four exquisitely cutting blades mounted on axis supported at both ends. Control console determines mode and speed of rotation. Oscillating cutting mode is recommended. Infusion is at the instrument's tip instead of its side. Unusually powerful but adjustable endo-illumination is available through fiberoptics. The fiberoptics tip is shaped to facilitate its introduction into the eye. A separate channel permits suction reversal. Five brief case descriptions illustrate versatility of the instrument. Its main advantages are its exquisite cutting properties, its powerful and adjustable endo-illumination, and its tip-end infusion hole.
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A specially designed silicone balloon, expanded in vivo with normal saline, was tested for possible use as a retinal tamponade in desperate cases of rhegmatogenous retinal detachment. In six pigmented rabbits there were extensive postoperative complications, but in eight owl monkeys results were noticeably better. When the seam of the balloon was in contact with the retina there were adverse effects; seamless areas of the balloon did not appear to disturb the retina. Histopathologic studies indicated that excessive expansion of the balloon can cause significant damage, but that carefully controlled expansion can probably minimize complications. The presence of the balloon appears to alter electroretinographic response, but without necessarily causing histopathologic changes. Balloons of this type have been used in treatment of a small number of otherwise inoperable cases of retinal detachment with promising results.
In 100 patients with fresh rhegmatogenous retinal detachments complete ocular and physical examinations including electrocardiograms were carried out. The incidence of coronary artery disease and systemic hypertension in these patients with retinal detachments was much greater than that found in the general population of similar age and sex. A vascular theory is proposed to explain these findings in light of our current concepts of the pathogenesis of retinal detachments. It is also suggested that retinal detachments may be one element of a generalized vasculopathy that involves the coronary arteries, the pulmonary vasculature, and perhaps the renal circulation in patients with systemic hypertension.
All patients were examined preoperatively and postoperatively by indirect ophthalmoscopy and biomicroscopy with a three-mirror lens. The average follow-up was eight months. Our technique of sclerotomy consisted of an incision parallel to the limbus, measuring 1.5 times the diameter of the surgical instrument. The pars plana location was always verified with transillumination. A mattress suture over the lips of the sclerotomy was used to prevent any leakage during the procedure. The intraoperative complications included ciliary body laceration (1%), retinal tears (8%), and vitreous base incarceration in the wound. The postoperative complications consisted of retina dragged into the wound (4%), vitreous tract left by the instrument (6%), neovascular ingrowth (6%), and external symptoms from the Dacron (32%) or polyglycolic acid (5%) suture. The rate of complications is considered low for such high-risk surgery.
Ten eyes developed fibrovascular ingrowth from the sclerotomy following closed vitreous surgery. The complication was detected by examining all patients postoperatively by indirect ophthalmoscopy and biomicroscopy with a three-mirror lens. The average follow-up was 13.2 months. Nine patients had proliferative retinal disease prior to surgery and related systemic disease. In six eyes, useful vision was lost due to the ingrowth. In three eyes, a stabilization occurred. In one eye, that of a 12-year-old girl with an undefined syndrome of cochlear and retinal neovascularization, the ingrowth involuted. Rubeosis iridis was observed in 6 eyes that developed vascular ingrowth as opposed to 11 eyes in a control group of 78 eyes. Eyes with rubeosis iridis should not have vitreous surgery, and careful dissection of the Tenon capsule should be done over the sclerotomy.
The Equator-Plus camera can photograph a 148-degree view of the fundus, measured from the nodal point of the eye. We tested this instrument clinically more than 800 times on over 700 eyes. The large field, which is three to four times that of any conventional fundus camera, is achieved by using a special contact lens as the front element in the camera optics. Photographs taken with the Equator-Plus camera can resolve a lesion as small as one-eighth of a disk diameter, if the contrast is good. Protruding tumors, choroidal or retinal detachment, and extensive disease of the choroid and fundus show up well with this technique. We obtained good pictures in 87% of the clinical tests. We have not observed complications of any kind after photography with the Equator-Plus camera.
When using an argon laser photocoagulator it is often advantageous and sometimes indispensable to treat the patient in a supine position. Stabilization of the laser beam requires the use of a microscope equipped with a beam manipulator (joystick) that maintains the orientation of the laser beam wherever it is placed, without the operator having to hold the joystick. A low-vacuum contact lens or a three-mirror lens, and a microscope suspended from a floor stand are used. The patient is placed in the supine position on a stretcher of adjustable height with his head in a foam rubber conformer. Local anesthesia may not be necessary, but if indicated, the patient should not be treated in an upright position. A lid block is rarely required. General anesthesia is used with patients who cannot cooperate. There are 4 main indications for treatment in the supine position: (1) cases in which great accuracy is needed, such as treatment near the macula; (2) all cases in which retrobulbar anesthesia is necessary, with or without a lid block; (3) cases in which the patient is unable to cooperate; and (4) cases that require prolonged photocoagulation.
The concept of "eye camp" represents a revolutionary approach to the massive problem of cataract-related blindness and visual disability. The "eye camp" involves comprehensive cooperative relief efforts on a large scale to combat the widespread incidence of cataract as it affects residents of rural areas, especially in developing nations. We worked in an eye camp in Johilpatti, India, in the rural province of Tamil Nadu. On this site, 216 cataract operations were performed in one morning by 8 doctors and 16 nurses. In this province alone, an estimated 700,000 persons have cataract requiring operation. However, presently existing facilities are equipped to handle a maximum of only 20,000 cases annually. But from June 1972 to June 1973, approximately 50,000 cataract operations were performed in the eye camps. Evidently, the eye camp idea has great potential to significantly reduce the incidence of untreated cataract in rural areas where there are chronic shortages of treatment facilities and medical personnel.
Communication between the retinal and the choroidal circulation occurred in one case of proliferative diabetic retinopathy and one case of Leber's disease (multiple miliary aneurysms) after argon laser photocoagulation treatment to eliminate abnormal retinal vasculature. In both instances rapid-sequence fluorescein angiography documented the choroidal origin of the anastomoses. Such anastomoses developed in areas where an excessively dense laser beam aimed at occluding retinal vessels presumably destroyed the underlying Bruch's membrane and permitted invasion of the retina by fibrovascular growth from the choriod. The occurrence of such growths is a potential complication of argon laser photocoagulation directly related to the power density used.