Cutaneous active vasodilation in humans is mediated by cholinergic nerve cotransmission.

During heat stress, increases in blood flow in nonglabrous skin in humans are mediated through active vasodilation by an unknown neurotransmitter mechanism. To investigate this mechanism, a three-part study was performed to determine the following: (1) Is muscarinic receptor activation necessary for active cutaneous vasodilation? We iontophoretically applied atropine to a small area of forearm skin. At that site and an untreated control site, we measured the vasomotor (laser-Doppler blood flow [LDF]) and sudomotor (relative humidity) responses to whole-body heat stress. Blood pressure was monitored. Cutaneous vascular conductance (CVC) was calculated (LDF divided by mean arterial pressure). Sweating was blocked at treated sites only. CVC rose at both sites (P < .05 at each site); thus, cutaneous active vasodilation is not effected through muscarinic receptors. (2) Are nonmuscarinic cholinergic receptors present on cutaneous arterioles? Acetylcholine (ACh) was iontophoretically applied to forearm skin at sites pretreated by atropine iontophoresis and at untreated sites. ACh increased CVC at untreated sites (P < .05) but not at atropinized sites. Thus, the only functional cholinergic receptors on cutaneous vessels are muscarinic. (3) Does cutaneous active vasodilation involve cholinergic nerve cotransmission? Botulinum toxin was injected intradermally in the forearm to block release of ACh and any coreleased neurotransmitters. Heat stress was performed as in part 1 of the study. At treated sites, CVC and relative humidity remained at baseline levels during heat stress (P > .05). Active vasodilator and sudomotor responses to heat stress were abolished by botulinum toxin. We conclude that cholinergic nerve activation mediates cutaneous active vasodilation through release of an unknown cotransmitter, not through ACh.

Malignant lesions of the eyelids.

BACKGROUND: The ocular adnexal area contains virtually every tissue type; nearly any type of malignant tumor may develop in this area. However, the vast majority of malignant eyelid tumors are carcinomas. Three types of carcinomas produce most of the malignancies in this group. They are: basal cell carcinomas, squamous cell carcinomas, and sebaceous cell carcinomas. OBJECTIVE: The management of these three tumors is discussed. METHODS: A review of current treatment options for eyelid malignancies was performed. RESULTS: A summary of the current treatment of the three most common eyelid carcinomas is discussed. CONCLUSION: With early recognition and appropriate management of eyelid malignancies, an extremely favorable prognosis can be obtained. The management is twofold and consists of curing the patient of the malignancy and then restoring the form and function of the eyelid in order to save the eye if possible.

Evaluation of a collagen/hydroxylapatite implant for orbital reconstructive surgery.

A variety of autogenous and alloplastic materials have been used to correct enophthalmos. Hydroxylapatite (HA), is a calcium-phosphate-based compound that has been extensively studied as a bone replacement material. We studied the properties of a new dense particulate form of HA in a collagen matrix (PFC/HA) implanted in the subperiosteal space of ten rabbit orbits for a period of 6 months. All animals were studied with pre- and postoperative computed tomography (CT) scans, and measurements of induced proptosis and implant volume were made. The proptosis induced by the implant averaged 2.2 mm and was stable over a 6-month period. Implant volume was constant throughout the study. Three-dimensional computer-generated images of the soft tissue, skeletal, and implant surfaces confirmed the implant stability. All animals were studied histologically with fluorochrome bone markers, which revealed minimal foreign body reaction to the implant, no evidence of infection, and marked fibrovascular ingrowth. We found the PFC/HA to possess properties that make it an ideal implant material: ease of availability, ease of handling, no resorption, minimal immunogenicity, infection resistance, no observed migration, biointegration, and no risk of disease transmission. PFC/HA may make an excellent implant material to manage orbital volume.

Multiple endocrine neoplasia type III.

The multiple endocrine neoplasia (MEN) syndromes are autosomally dominant inherited disorders in which hyperplastic or neoplastic changes occur in a wide variety of tissues. The specific syndromes are classified according to the endocrine glands affected. MEN type I consists of an aggregation of tumors of parathyroid, pancreatic, and pituitary glands. The association of medullary carcinoma of the thyroid (MCT) and pheochromocytoma is called MEN type II or type IIA, and if combined with mucosal neuromas, intestinal ganglioneuromatosis, and prominent corneal nerves, is named MEN type III or type IIB. Individuals afflicted with MEN type III are characterized by a marfanoid habitus, mucosal neuromas involving oral and ocular tissues, and a number of ophthalmologic findings including prominent corneal nerves, thickened eyelids, and subconjunctival neuromas. These features are easily recognized during the ocular exam, allowing the ophthalmologist to make an early diagnosis of this syndrome prior to the onset of life-threatening manifestations like medullary thyroid carcinoma and pheochromocytoma.

Medial and lateral wall decompression for thyroid ophthalmopathy.

A two-wall decompression of the orbit, consisting of removal of the medial and lateral walls, was successful in eight patients with thyroid ophthalmopathy. The lateral wall was by removed by using the standard orbitotomy technique in addition to enlarging the space with a pneumatic burr, and the medial wall was removed through a direct medial canthal incision. Two patients had optic neuropathy, one had intermittent subluxation of the globe, and five had symptoms of exposure or increased pressure in the orbital area. In our eight patients, the two with optic neuropathy improved, the patient with subluxation of the globe became asymptomatic, and the other five had less exposure and were more comfortable. The amount of decompression ranged between 4 and 7 mm. The lacrimal sac was injured in one patient; temporary silicone intubation avoided any permanent sequela.

Comparative histopathologic study of various lens biomaterials in primates after Nd:YAG laser treatment.

A Nd:YAG laser was used to perform posterior capsulotomies on primates in whom one-piece silicone or three-piece polymethylmethacrylate intraocular lenses were in place for more than one year. The eyes were followed for eight weeks after treatment before enucleation. Histologically, no toxic effects caused by the dispersion of any of the biomaterial within the eyes and no significant inflammatory reactions were seen. The silicone lenses used in this study compared favorably with traditional polymethylmethacrylate lenses when posterior capsulotomies with a Nd:YAG laser were performed.

Localized endophthalmitis: a newly described cause of the so-called toxic lens syndrome.

We report five cases of post-extracapsular cataract extraction infection in which subsequent pathologic analyses identified the organisms and found the infection to be localized or confined to the lens capsular sac. The most common offending organisms were gram-positive pleomorphic bacilli. In one case, we were able to identify the bacteria as Propionibacterium acnes. We designate this condition a localized endophthalmitis. It should be considered any time a persistent, smoldering, postoperative inflammation occurs, and in the differential diagnosis of phacoanaphylactic endophthalmitis. The condition itself is not new, but undoubtedly many such cases have gone unrecognized or have been misdiagnosed as the so-called toxic lens syndrome. In localized endophthalmitis, a clinically visible inflammatory process may occur even when multiple diagnostic taps are negative, although when the cases first appeared, the surgeons were not aware of the entity and anaerobic cultures were not always obtained. A negative tap may be explained by the fact that metabolic products from the organisms are released from the bag into the anterior segment and vitreous. A synergistic reaction may occur between these organisms and retained lens cortical remnants that may cause or exacerbate a hypersensitivity reaction. The condition may be worsened by Nd:YAG capsulotomy. The pathogenesis of localized endophthalmitis has nothing to do with the type of intraocular lens fixation (lens capsular sac or ciliary sulcus); rather, the simple presence of a capsular sac after extracapsular cataract extraction is the prerequisite for the clinical condition.

Visual aberrations caused by optic components of posterior chamber intraocular lenses.

A 58-year-old airline pilot had cataract surgery with implantation of a posterior chamber intraocular lens with four positioning holes around the optic edge. During periods of maximum pupil dilation, such as at night, visual aberrations including glare, monocular diplopia, and haloes occurred and he was unable to work in his occupation. The symptoms were severe enough that lens exchange was required, and a posterior chamber lens with no positioning holes was successfully implanted. The symptoms immediately subsided postoperatively and his last known visual acuity was 20/15. This case, and the report of another patient with similar postoperative problems, illustrates that implantation of lens optics with a larger effective optical zone for posterior chamber lens implantation is desirable. This is particularly true now that younger, more active patients, many still engaged in occupations, are having lens implantations.

Posterior chamber intraocular lenses in a series of 75 autopsy eyes. Part III: Correlation of positioning holes and optic edges with the pupillary aperture and visual axis.

The possibility that undesirable visual complications such as glare, halo, monocular diplopia, or other visual aberrations can result from the presence of posterior chamber lens optic edges or such lens elements as positioning holes or loop-optic junctions within the pupillary aperture has received little attention. There is recent clinical evidence that these phenomena may be clinically significant. In a series of 75 autopsy eyes with posterior chamber intraocular lenses, we have observed that in 71% of cases an optic edge, or element of the optic such as a positioning hole, was situated either within the pupillary aperture and visual axis (average pupillary diameter 3.45 mm) or within 0.5 mm of the pupillary margin. This finding was most common (92%) in cases with asymmetric placement, less common (50%) in cases with symmetric placement. Many more young patients are now undergoing implantation surgery. These patients generally have wider, more mobile pupils, and they may be more aware of subjective symptoms, particularly at night. Subtle changes in implantation techniques and in lens design and manufacture can minimize complications related to this condition. These changes include symmetric loop placement (both loops in the capsular sac or both in the ciliary sulcus) to decrease optic decentration. Other measures such as making partial-depth positioning holes, increasing the size of the optic, eliminating or reducing the number of positioning holes, and placing positioning holes in tabs on the optic edges may function to increase the effective optical zone.

Posterior chamber intraocular lenses in a series of 75 autopsy eyes. Part I: Loop location.

Over a period of 27 months, November 1983 to February 1986, 75 eyes obtained postmortem with posterior chamber intraocular lenses (IOLs) were examined at the Center for Intraocular Lens Research, University of Utah Health Sciences Center. These IOLs were studied by histopathological techniques to determine the location of the loops. The most common combination, found in 47% of the specimens, was one loop in the lens capsular sac (bag) and one loop in the ciliary sulcus. In 32% of the specimens, both loops were in the capsular sac; in 17%, both loops were in the ciliary sulcus. Compared to results observed in other autopsy studies, in which capsular fixation was documented in less than 3% of cases, these findings reflect a trend toward capsular sac (in-the-bag) implantation of open-looped posterior chamber IOLs.