A model for the mechanism of optic nerve sheath fenestration.

The mechanism by which optic nerve sheath fenestration relieves papilledema associated with increased intracranial pressure has not been clearly defined. A model was constructed to determine if the induction of fluid flow along the nerve sheath and through the fenestration could account for a reduction in pressure around the optic nerve, as might be expected according to Bernoulli's equation of fluid dynamics. The model states that as the velocity of a fluid increases, the pressure it exerts decreases. The model simulated fluid spaces corresponding to the intracranial vault, chiasm, and optic nerves. The unfenestrated model showed direct transmission of elevated intracranial pressure to the nerves, consistent with the production of papilledema. When one nerve was fenestrated, fluid flow along the nerve was initiated and pressure in that nerve sheath dropped substantially. In addition, pressure in the unfenestrated sheath dropped due to fluid communication across the chiasm. These lower intrasheath pressures were consistent with the bilateral resolution of papilledema after unilateral fenestration. The reduced intrasheath pressures persisted even when the intracranial pressure was again elevated to pathologic levels as long as active fluid flow continued along the nerve sheaths. Thus, induction of cerebrospinal fluid flow along the optic nerve sheath by fenestration appears to locally reduce the pressure around the optic nerve, in spite of persistently elevated intracranial pressure. This is in accordance with what would be predicted by Bernoulli's equation.

Cyanoacrylate-fixed silicone sleds in the orbit. An animal model.

Subperiosteal wedge-shaped sleds of various materials have been used in treating the enophthalmic anophthalmic socket and in correcting the enophthalmic seeing eye. Posterior fixation of the sled may be difficult, as the sled tends to migrate anteriorly. Tissue adhesives were studied as a fixation method for silicone sleds in rabbit orbits. Gross examination revealed that the sleds were secured in position until well encapsulated. Butyl 2-cyanoacrylate (Histoacryl Blue) induced minimal inflammation, while ethyl cyanoacrylate (Crazy Glue) caused a giant-cell response.

Intraocular coccidioidomycosis diagnosed by skin biopsy.

OBJECTIVE: To describe ocular findings in 2 patients with disseminated coccidioidomycosis diagnosed by skin biopsy. METHODS: The clinical and histopathologic findings of the 2 patients were reviewed retrospectively. RESULTS: One patient had a unilateral, granulomatous iridocyclitis with multiple iris nodules and a large vascularized anterior chamber mass, in the setting of pulmonary, cutaneous, and skeletal infection by Coccidioides immitis. The second patient developed papilledema and multifocal chorioretinitis accompanied by pulmonary, cutaneous, and meningeal C immitis infection. In each case, examination of the skin biopsy specimen revealed C immitis spherules. Treatments included local and systemic amphotericin B and oral fluconazole. CONCLUSIONS: Although rare, intraocular involvement can occur in the setting of disseminated coccidioidomycosis. A thorough systemic evaluation and biopsy of suspicious skin lesions can aid in the diagnosis.

Orbital optic glioma in neurofibromatosis. Magnetic resonance diagnosis of perineural arachnoidal gliomatosis.

In a patient with neurofibromatosis and orbital optic glioma, T2-weighted axial magnetic resonance images showed a fusiform area of high signal intensity with a central linear core of lower signal intensity. Computed tomographic images did not show a corresponding variation in tumor density. Histopathologic examination of the tumor revealed dense, circumferential, perineural glial proliferation. This "arachnoidal gliomatosis" is a feature of orbital optic gliomas in neurofibromatosis and, in our magnetic resonance scans, accurately corresponded with the region of high signal intensity within the tumor.

Nasolacrimal drainage system obstruction after orbital decompression.

We reviewed 123 cases of orbital decompression in 63 patients with dysthyroid ophthalmopathy. Of 90 cases of transantral ethmoidal orbital decompression, 14 (16%) resulted in epiphora. The tearing began between 11 and 18 months after surgery. All patients had obstruction distal to the common internal punctum. The delayed onset suggested progressive cicatricial obstruction of the nasolacrimal drainage system. Damage to adjacent tissues probably caused scarring to extend into the system.

Outcomes of cataract surgery by residents at a public county hospital.

PURPOSE: To determine whether outcomes of extracapsular cataract surgery with intraocular lens implantation performed by residents at an urban county hospital are comparable to previously reported patient outcomes at Veterans Affairs and university hospitals. METHODS: We performed a retrospective analysis of all extracapsular cataract procedures with intraocular lens implantation, both by standard extracapsular cataract extractions and by phacoemulsification, performed by first-year, second-year, and third-year residents at San Francisco General Hospital from January 1, 1994, through June 30, 1995. RESULTS: Final best-corrected visual acuity of 20/40 or better was achieved in 183 (84%) of 218 eyes. When patients with preexisting eye disease limiting visual potential were excluded, 20/40 or better visual acuity was achieved in 159 (94%) of 169 eyes. Vitreous loss occurred in six (16%) of 37 eyes operated on by first-year residents, in six (10%) of 63 eyes operated on by second-year residents, and in seven (6%) of 118 eyes operated on by third-year residents. The mean change in vision was a gain of 6 lines of Snellen acuity. CONCLUSIONS: Patients undergoing cataract surgery performed by residents at an urban county hospital have visual outcomes equivalent to those of patients at Veterans Affairs and at university facilities.

Treatment of facial palsies with external eyelid weights.

PURPOSE: Because ocular exposure is a major complication of facial paralysis, an external gold eyelid load weight was evaluated for effectiveness in the treatment of this problem. METHODS: We prospectively studied 12 patients with unilateral facial paralysis who were treated with the external eyelid weights. Follow-up examinations included corneal exposure, amount of artificial tear usage, patient comfort, and complications associated with the weights. Treatment end points were the patient's decision to undergo a canthoplasty or placement of an implanted weight or resolution of the facial paresis to better than House's grade IV/VI. RESULTS: Of the 12 patients studied, ten had decreased corneal exposure on the affected side, with a coincident decrease in artificial tear drop use and increased comfort. One patient had no improvement in a corneal defect, and one was unable to apply the weight. Five patients had some difficulty in positioning the weight, which was related to upper eyelid dermatochalasis in four of the five. Only two weights were lost in over two years of total wearing time. CONCLUSIONS: External eyelid weights are useful in the treatment of ocular exposure associated with facial paralysis. The weights decreased corneal exposure, decreased reliance on artificial tear drops, and increased patient comfort. The weights were helpful as a trial before implantation of eyelid weights and as a longer-term treatment for ocular exposure in patients with temporary facial paralysis. Loose upper eyelid skin may limit their usefulness in some patients.

The use of botulinum toxin in blepharospasm.

Twenty-two patients, 17 with benign essential blepharospasm and five with hemifacial spasm, received botulinum toxin by subcutaneous injections in the eyelids and eyebrows. All 22 patients received a standard treatment of 12.5 units of botulinum toxin per side at each injection session. The orbicularis oculi muscle showed pronounced weakness after injection and the spasms decreased. Spasms often recurred despite persistent orbicularis oculi muscle weakness. Side effects were minimal. All patients received some relief, which generally lasted six to 12 weeks.

Computed tomographic evaluation of the optic canal in sudden traumatic blindness.

Using computed tomographic scans and reformatted images of the optic canal region, we were able to define osseous abnormalities in nine patients with sudden traumatic blindness resulting from indirect trauma to the optic nerve. Six patients had optic canal fractures, two had fractures of adjacent structures, and one patient did not have a fracture. Patients received corticosteroid therapy, surgical decompression of the optic canal, both types of treatment, or no specific treatment for the nerve injury. Although there was no correlation between the abnormality identified by computed tomography and treatment results, our findings provided further evidence that a canal fracture is not necessary for injury of the optic nerve to occur. We recommend that patients with sudden visual loss after blunt head trauma undergo a computed tomographic scan of the optic canal region.

Assessing the risk of retinitis pigmentosa with age-of-onset data.

Early characteristic electrophysiologic and ophthalmoscopic changes may help predict the development of retinitis pigmentosa. Until recently, if these were absent or equivocal, the ophthalmologist had to rely on the family pattern of transmission and simple Mendelian genetic methods to calculate the patient's risk of manifesting the disease. We used data on age of onset of subjective night blindness in 229 patients with retinitis pigmentosa (189 with autosomal recessive disease, 27 with autosomal dominant disease, and 13 with X-chromosome-linked disease) with Bayesian methods of probability calculation to predict the risk of retinitis pigmentosa development in a given patient more accurately than is possible with simple Mendelian methods. The risk for one subject used as an example was reduced from 50% to 12.9%.

Retinitis pigmentosa without pigment.

Sixty-eight consecutive patients with retinitis pigmentosa were studied to determine the frequency of the nonpigmented form of the disease. There was an overall incidence of 22%. Fifty percent of all cases had no characteristic pigmentation, if the duration of night vision difficulty was three years or less. The nonpigmented form of retinitis pigmentosa was frequently an early stage of the disease and not an unusual or atypical variant. Patients without the pigmentary changes characteristic of the disorder also showed less functional impairment: the electroretinographic b wave was more apt to be recordable, although impaired, and the rod threshold, as determined by dark adaptation measurement, was less elevated. The clinician should suspect retinitis pigmentosa, even in the absence of pigmentary changes, if there is a family history of the disorder, night blindness, peripheral field loss, and an impaired or nonrecordable electroretinographic response.

Tarsal margin rotation with posterior lamella superadvancement for the management of cicatricial entropion of the upper eyelid.

PURPOSE: To report the efficacy of tarsal margin rotation with posterior lamella superadvancement in the management of cicatricial entropion of the upper eyelid. METHODS: In 15 consecutive patients, 22 eyelids with cicatricial entropion were managed with tarsal margin rotation and posterior lamella superadvancement. In a retrospective study, the technique and results were evaluated. RESULTS: In all 22 upper eyelids, the normal eyelashes rotated away from the surface of the eye. Mean follow-up was 12.9 +/- 12.4 months (range, 1 to 48 months). One eyelid developed buckling of the tarsus. Three eyelids needed electrolysis to treat isolated metaplastic cilia posterior to the normal lash line. CONCLUSIONS: Tarsal margin rotation with posterior lamella superadvancement appears to be effective in managing cicatricial entropion of the upper lid.

Decompression of the optic nerve sheath for vision-threatening papilledema caused by dural sinus occlusion.

Obstruction of the dural sinuses produces a clinical syndrome that resembles pseudotumor cerebri. In these patients, unremitting papilledema can cause blindness. We performed decompression of the optic nerve sheath in four patients who had occlusion of the dural sinuses. The operation achieved rapid relief of papilledema and recovery of vision. In three patients, fenestration of the nerve sheath of only one eye resulted in resolution of papilledema in both eyes. The procedure appears to relieve papilledema by filtering small quantities of cerebrospinal fluid into the orbit. It did not lower cerebrospinal fluid pressure in three patients who underwent lumbar puncture after surgery. Optic nerve sheath decompression is an effective operation for salvage of vision in patients with obstruction of the dural sinuses.

Histopathological evaluation of rotation sutures for involutional entropion.

Rotation sutures are a popular method of temporarily correcting involutional entropion. The permanence of the procedure depends on a fibrotic scar along the suture tracks. Sutures which create generous scars would probably produce the most satisfactory results. In this study 4-0 chromic gut, nylon, and silk sutures were evaluated in rabbit lower eyelids for their ability to create histologically demonstrable fibrous tracks. All three sutures incited inflammatory cells and fibroblastic activity with collagen formation at two and four weeks. Residual scar tracks were observed at six weeks (two weeks after suture removal) also. Human specimens showed similar types of scar formation from the sutures. It was apparent that all three sutures create fibrotic scars along their tracks sufficient to correct, at least temporarily, involutional entropion.

Use of botulinum toxin to treat blepharospasm in a 16-year-old with a dystonic syndrome.

A 16-year-old boy with generalized dystonia had continuous, severe blepharospasm and facial grimacing. Local intradermal injections of botulinum A toxin greatly reduced the spasms and improved function. No side effects were observed. Local botulinum A toxin injections may be useful in the treatment of eyelid and facial spasms in patients with generalized dystonias.

The clinical significance of retinitis pigmentosa without pigment: a computer assisted analysis.

Sixty-eight consecutive patients with retinitis pigmentosa were studied to determine the frequency of the non-pigmented form of the disease. There was an overall incidence of 22%. Fifty percent of all cases had no characteristic pigmentation, if the duration of night vision difficulty was three years or less. The study lends statistical support to the concept that the non-pigmented form of retinitis pigmentosa is frequently an early stage of the disease and not an unusual or atypical variant. Patient without the pigmentary changes characteristic of the disorder also showed less functional impairment: the ERG b-wave was more apt to be recordable, although impaired; and the rod threshold, as determined by dark adaptation measurement, was less elevated. The clinician should suspect retinitis pigmentosa, even in the absence of pigmentary changes, if there is a family history of the disorder, night blindness, peripheral field loss, and an impaired or non-recordable electroretinographic response.

Upper eyelid gold weight implantation in the Asian patient with facial paralysis.

Patients with facial paralysis may develop ophthalmic complications. Poor eyelid closure and lagophthalmos place the patient at increased risk for the development of corneal problems such as epithelial defects, stromal thinning, bacterial infection, and even perforation. Initial treatment should be conservative and include the use of ocular lubricants, moisture chambers, and taping of the lower eyelid into proper position. Surgical intervention may be required in patients who have failed medical therapy or in whom the facial paralysis is not expected to improve. Gold weight implantation in the upper eyelid has become a popular procedure to correct upper eyelid retraction and to improve corneal coverage. Previous descriptions of gold weight placement in the upper eyelid have focused on Caucasian eyelid anatomy. However, there are distinct anatomic differences between the Caucasian and Asian eyelids, which dictate the overlying aesthetic differences. We describe our technique for placement of a gold weight in the Asian upper lid, with attention to the maintenance of symmetric eyelid creases. We reviewed the charts of six Asian patients with facial paralysis who underwent gold weight placement in the upper eyelid for the correction of lid retraction. All patients did well functionally and aesthetically, and none developed an extrusion of the implant with this approach.

Management of ophthalmic complications of facial nerve palsy.

Six stages--supportive care (with or without tarsorrhaphy), planning for facial reanimation, lower eyelid and lateral canthal resuspension, passive upper eyelid reanimation, dynamic eyelid reanimation, and soft tissue repositioning--should be considered in the management of the ophthalmic complications of facial nerve palsies. Each stage should be considered in order, although action in each stage may not be appropriate for all patients. In addition, after appropriate consideration, two or more staged procedures may be performed at the same time. Treatment may be held at any stage in which the cornea is compensated and the patient is comfortable and happy. By employing this staged approach, the surgeon has a method of organizing therapy in a logical fashion, and the patient is offered a set of reassuring goals, which combine to make the treatment plan more effective.

Ophthalmic complications of water sports.

Those who participate in aquatic sports are at risk for some special ocular problems. These have been outlined here and include optical problems and refractive errors, pressure related disease, ocular trauma, infections and irritations, toxins, and complications of exposure to sun and wind. Awareness of these disorders may allow better management and prevention.