Incomplete Cut Research Articles

New Surgical Strategy for Corneal Tattooing Using a Femtosecond Laser

The purpose of this study was to describe a new method of femtosecond (FS) laser-assisted corneal tattooing and to report the results of this method in a case series. The study involved 6 eyes of 6 patients with total or partial corneal opacity. An FS laser was used for lamellar dissection and to make a side cut with a hinge, creating a corneal flap. Laser parameters were adjusted depending on ocular condition and the location of the corneal opacity. After lifting the corneal flap, further lamellar dissection with a diamond blade was performed up to the periphery of the limbal area. Using a cannula, dye was injected into the lamellar stromal bed and the space of the lamellar dissected pocket in the limbus, after which the flap was repositioned. The design and application of the FS laser for dissection and flap creation were successful in all cases. There were no significant complications other than an incomplete cut under band keratopathy in 1 eye. The cosmetic effects were satisfactory in all cases. No patient complained of pain for more than 1 day after surgery. The advantages of the FS laser-assisted corneal tattooing include a customized design, speed, decreased pain, reduced risk of perforation, and good wound healing. This procedure provides improvements over current corneal tattooing techniques, although it is relatively expensive.

Laser in situ keratomileusis: Literature review of a developing technique

We reviewed papers published in peer-reviewed journals describing techniques and results of laser in situ keratomileusis (LASIK) and summarized the instruments used, nomograms, preoperative and postoperative refractions, predictability, outcome, safety, and complications. We performed a similar review of abstracts published in the abstract books of the 1996 meeting of the International Society of Refractive Surgery, the 1997 meeting of the Association for Research in Vision and Ophthalmology, and the 1997 meeting of the American Society of Cataract and Refractive Surgery. The number of LASIK and photorefractive keratectomy (PRK) patients described in the abstracts were sorted by city. Mean weighted latitudes were calculated and compared for each procedure. The mean preoperative refraction in the papers was −12.59 diopters (D), which was statistically higher than that in the abstracts, −8.71 D (P < .001), and the mean postoperative refraction, −1.10 and +0.93 D, respectively. The mean percentage of cases within ±1.00 D was 67.0% in the papers and 82.5% in the abstracts. Uncorrected visual acuity (UCVA) of 20/40 or better was achieved in 49.2% of eyes in the papers and 83.2% of those in the abstracts; a UCVA of 20/20 or better was achieved in 22.0 and 56.6%, respectively. The proportion of eyes that lost two or more lines of best corrected visual acuity was 8.0% in the papers and 0.9% in the abstracts. Complications in the papers included irregular flap (4.0%), incomplete cut (2.5%), free cap (4.9%), perforated lenticule (2.6%), short flap (3.0%), sliding flap (1.4%), interface debris (6.8%), central island (5.3%), decentration (4.7%), epithelial ingrowth (4.3%), induced astigmatism (5.1%), wrinkles (5.9%), haze (8.7%), night vision problems (14.0%), and reoperation (8.2%). Mean latitude for LASIK cases (27.00 degrees ± 13.73 [SD]) was significantly lower than that for PRK cases (42.85 ± 11.7 degrees). Visual outcomes of LASIK surgery show significant improvements when recent abstracts are compared with published papers. This may reflect continued improvement in the surgical techniques, surgeons' skills, and visual outcomes.

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The Bernese periacetabular osteotomy described by Ganz et al restores the position and acetabular coverage of the dysplastic hip to nearly normal, but it has several disadvantages due to the asphericity of the osteotomy surfaces. Because this osteotomy is a series of straight cuts, incongruity at the site of the osteotomy and anterior displacement of the hip joint may occur in patients who need an extensive acetabular reorientation. We designed a curved periacetabluar osteotomy to improve these drawbacks.The direct anterior approach described by Murphy et al is used with the patient supine. The triple osteotomy is done with a specially curved osteotome, designed to approximately correspond to the circumferential curvature of the acetabulum. Except for the use of the osteotome, an incomplete cut of the ischium and a complete cut of the pubis are performed in the similr manner as those of the Bernese periacetabular osteotomy. The first step in osteotomy of the ilium is to score the inner table of the pelvis with a power drill. A C-shaped osteotomy line is started proximal to the anteroinferior iliac spine and ended in the distal part of the quadriilateral surface. The actual osteotomy along the scored line is done with the osteotome being directed proximally in the supraacetabular portion, posteriorly in the proximal part of the quadrilateral surface, and distally in the distal part of the quadrilateral surface. Then, the acetabular fragment can be redirected and is fixed with two or three screws. The posterior column of the acetabulum is kept intact. The results of the first 24 hips in 24 patients were prospectively studied with a minimum of 6-month follow-up. All hips had residual hip dysplasias. At operation, the osteotomized acetabular fragment was rotated without difficulty and was medialized as necessary. The averge lateral center-edge angle was 6 degrees preoperatively, compared with 29 degrees postoperatively. The average anterior center-edge angle was 8 degrees preoperatively, compared with 26 degrees postoperatively. Bone union and relief of pain were obtained in all hips.

Model nerve net can produce rectilinear, non-diffuse propagation as seen in the skin plexus of sea urchins

One of the simplest puzzles in neural connectivity is what can be the basis of the spine-converging or pointing response of echinoids to touch. Mediated by a conduction system in the skin, it is unique among known epithelial systems (unpolarized, Hopfield type nets) in propagating without significant curvature past the end of an incomplete cut, leaving a basically straight-edged shadow of no response. Known since 1881, this was analyzed by Bullock (1965, Comparative aspects of superficial conduction systems in echinoids and asteroids Am. Zool. 5, 545–562), who believed it demands that the plexus contains discrete, straight chains of neurons between every sensory site and every spine within 3 cm, a “curious and unprecedented” connectivity which seemed unlikely (here called “star” models). The present paper proposes a class of models by which non-diffuse, rectilinear propagation can occur in diffusely connected nerve nets. It requires that each neuron be influenced by several hundred neighbors, and that the average neuronal firing threshold be adjusted rather precisely. A threshold area must be initially stimulated. Several modifications approach realism based on animal data. It is shown by computer simulation that the proposed models support rectilinear propagation, and are insensitive to many changes in the detailed structure. Neither the present class nor the star models can be excluded on the present knowledge of anatomy of the echinoid plexus; they are viable alternatives. Tests of the two are proposed. Neither seems likely to be correct and we do not consider the puzzle solved.

Evidence that the anterior hypothalamus contributes to the control of tonic secretion of follicle-stimulating hormone in the female rat.

A horizontal knife cut was placed between the dorsal anterior hypothalamic area (DAHA) and the medial basal hypothalamus to examine the role of the DAHA in the selective secretion of follicle-stimulating hormone (FSH) following unilateral ovariectomy (ULO) and bilateral ovariectomy of the rat. Complete cuts markedly attenuated the increase in FSH observed 8 h after ULO, whereas incomplete or sham cuts did not. Concentration of luteinizing hormone (LH) did not increase in any group. These cuts also blocked the prolongation of estrous FSH secretion observed in long-term hemicastrated rats, since FSH levels on estrus were significantly lower in rats with complete cuts than in those rats given sham or incomplete cuts. In contrast, neural surgery had no effect on proestrous FSH concentrations. Finally, when FSH levels were monitored 2 days after bilateral ovariectomy, the postcastration rise in FSH was not altered by any neurosurgical procedures. These results support the hypothesis that a neural system originating in, or passing through, the DAHA is necessary for the selective increase in FSH following ULO.

Saphenous neuralgia: a complication of arterial surgery.

The saphenous nerve may be damaged during arterial surgery in the thigh as it emerges through the aponeurotic covering of the adductor canal. A clean cut of the nerve gives rise to anaesthesia, but an incomplete cut or tearing of the nerve, followed by its involvement in scar tissue, leads to saphenous neuralgia--a painful sensation in the area supplied by the nerve. Two hundred and fifty-seven arterial operations involving the course of the saphenous nerve in the thigh have been reviewed. Twenty-six of these operations were complicated by early failure of the arterial procedure necessitating amputation and have not been considered in assessing the incidence of damage to the nerve. One in five superficial femoral thromboendarterectomies and one in nine femoropopliteal bypass grafts were complicated by saphenous neuralgia. Profundaplasty was not followed by this complication. Appreciation of this troublesome symptom should lead to greater care of the nerve during surgery.

An electromagnetic biopsy device

This communication describes an electromagnetic biopsy device built at the Electronics Department of the Weizmann Institute, Israel, and presently undergoing evaluation at Tel-Hashomer Hospital. The device is intended to obtain biopsy samples froom the gastrointestinal tract after introduction through the natural openings to this tract. It wras originally intended to develop a device which would be easily passed, would be capable of taking multiple cuts without having to be withdrawn and reset after each cut, would not accidentally trip while being directed to the site of interest, could be backed off an incomplete cut and would permit the degree of vacuum to be con-trolled independently of the force activating the knife. This latter condition allows better control of the size of the biopsy speclimen than is achieved with several available devices.

Self-Supporting Heating Element

A heating element design is described, applicable to graphite or sheet metal, which has an electrical resistance comparable to a helix and a structural rigidity comparable to a cylinder. Incomplete cuts perpendicular to the axis create a number of electrically long paths in parallel, each with relatively short distances between regions of mechanical support.