MRI in Lhermitte-Duclos disease.

Lhermitte-Duclos disease (LDD) is a disorder sometimes referred to as a dysplastic gangliocytoma of the cerebellum. This is a focally indolent growth of the cerebellar cortex in which the folia enlarge due to a profusion of dysplastic cortical neurons and a thickening of the molecular layer. Loss of Purkinje cells and thinning of medullary white matter results. The enlarged folia lose their secondary foldings and asymmetrically expand the cerebellar hemisphere. These morphologic features produce a characteristic pattern on some CTs and all MRIs, affording an opportunity for a preoperative diagnosis. MRI of a pathologic specimen suggested that the abnormal T1 and T2 signals corresponded to the atrophic folial white matter, thickened granule cell layer, and outer molecular layer. Because of inherent Hounsfield artifact in posterior fossa with CT, MRI is the imaging modality of choice, with better visualized striated pattern. The uniqueness of these imaging features obviates the need for an obligatory biopsy for asymptomatic patients and either permits more definitive planning for surgical decompression or, in restricted lesions, guides more assuredly complete excision of the cerebellar mass.

Infection after radial keratotomy.

PURPOSE/METHODS: Eight years after eight-incision radial keratotomy, a corneal ulcer developed around the inferotemporal incision in an otherwise healthy 39-year-old man. There was no history of corneal trauma or contact lens wear. RESULTS/CONCLUSIONS: Both Fusarium and Acanthamoeba organisms were eventually isolated from the ulcer. A therapeutic keratoplasty was performed. Inferotemporal incisions may be predisposed to epithelial breakdown and infection many years after radial keratotomy.

Clinical evaluation of the anterior constant focus (ACF) annular bifocal contact lens.

We evaluated the distance and near vision of 33 presbyopic patients who wore the Anterior Constant Focus (ACF) rigid gas permeable (RGP) bifocal lens. Twenty-seven patients (82%) wore the lenses for one year; the six patients who quit the study complained of unacceptable vision (four patients) and discomfort (two patients). Twenty-five patients (76%) obtained 20/25 or better distance vision, and 28 patients (85%) obtained J2 or better near vision. Contrast sensitivity was within normal limits in 24 of 33 (73%) patients. We feel the ACF lens provides good bifocal vision in a non-translating RGP design.

Incidence and management of complications of transsclerally sutured posterior chamber lenses.

Thirty eyes with an average follow-up of 23 months following transscleral fixation of a posterior chamber intraocular lens (IOL) were retrospectively reviewed for complications. The most common complication was erosion of the polypropylene suture knots through half thickness scleral flaps (22 eyes, 73%). The average time for suture erosion through the sclera was 9.4 months (range one to 12). The polypropylene suture knots eroded through the conjunctiva in five eyes (17% incidence) at an average of 12 months postoperatively (range six to 18 months). All conjunctival erosions were surgically repaired. Other complications included clinically significant lens tilt/decentration (3/30, 10%), open angle glaucoma (5/30, 17%), and suprachoroidal hemorrhage (1/30, 3%). The complications associated with transscleral fixation of posterior chamber IOLs are distinctly different from those associated with anterior chamber IOLs. Prospective clinical trials may provide further information about pseudophakic rehabilitation in the absence of capsular support.

A clinical evaluation of two multifocal soft contact lenses.

We fit two multifocal soft contact lenses, Bausch & Lomb's Bi-Tech and the Unilens contact lens from Unilens Corporation, in two separate populations of presbyopes. Most patients (24/42, 57%) had no prior contact lens experience. Patients were evaluated at 6 and 12 months for comfort, visual acuity, lens fit, and corneal findings. Both distance and near vision were found to be slightly decreased with each contact lens when compared to best corrected visual acuity with spectacles. Seventy-seven percent (14/18) of the Unilens wearers and 67% (16/24) of the Bi-Tech wearers continued to wear their lenses for at least 1 year. Those who discontinued lens wear did so because they were dissatisfied with their vision. Presbyopes who seek correction with soft contact lenses appear to be more tolerant of a decrease in distance vision than a decrease in near vision. Both lenses were comfortable and no corneal pathology was induced. Our results suggest that the Unilens (simultaneous vision design) provides more predictable correction of presbyopic symptoms than the Bi-Tech (alternating vision design) because it is independent of lower lid position and translation. Both of these lenses are viable options for the correction of presbyopic symptoms.

Clinical evaluation of the Tangent Streak trifocal contact lens.

The Tangent Streak trifocal is a rigid gas permeable contact lens with horizontal segments for distance, intermediate, and near correction. We undertook a prospective clinical evaluation of the Tangent Streak trifocal to determine the efficacy of this lens in correcting presbyopic symptoms. Distance, intermediate, and near corrections were compared using visual acuity and contrast sensitivity charts in 25 presbyopic ametropes. Compared to the original bifocal correction, the Tangent Streak trifocal provided 21 of 25 of study patients (84%) with subjectively improved intermediate vision, while maintaining distance and near vision. Twelve of 16 dissatisified bifocal contact lens wearers (75%) were successfully fit with the Tangent Streak trifocal. This study shows that the Tangent Streak trifocal lens can effectively provide multifocal vision to presbyopic ametropes.

Postkeratoplasty astigmatism control. Single continuous suture adjustment versus selective interrupted suture removal.

Two different suturing techniques performed during keratoplasty were retrospectively evaluated to compare postkeratoplasty astigmatism, number of suture manipulations, and time to optical stability. One group of patients (n = 31) received a combination of continuous 11.0 nylon suture and 12 or 16 interrupted 10.0 nylon sutures (CCIS), which were selectively removed post-operatively to reduce astigmatism. The second group of patients (n = 26) received a single continuous 10.0 nylon suture (SCS) that was adjusted postoperatively at the slit lamp to regulate corneal astigmatism. Compared with the CCIS technique, adjusting the single continuous suture resulted in less postoperative astigmatism (SCS, 1.5 +/- 1.1 diopters [D]; CCIS, 3.2 +/- 1.9 D), fewer suture manipulations per patient (SCS, 0.9 +/- 0.7; CCIS, 3.8 +/- 1.8), and earlier optical stability for visual rehabilitation (SCS, 2.6 +/- 1.5 months; CCIS, 9.6 +/- 4.7 months) (P less than 0.01). No continuous sutures were broken during adjustment. The adjustable single continuous suture may offer an improved method for early control of postkeratoplasty astigmatism.

Clinical study of keratoconus in central Kentucky.

Keratoconus is an ectatic corneal disorder that results in a central or inferior conelike anterior protrusion. This results in irregular myopic astigmatism, causing considerable visual impairment. We have completed a retrospective clinical study of keratoconus in the central Kentucky area. When compared to other national studies of keratoconus, our study patients generally had more severe disease at the time of diagnosis and had a higher rate of keratoplasty. Keratoconus treatment is highly successful, and early diagnosis is warranted to prevent unnecessary visual loss.

Collagen shield delivery of trifluorothymidine.

Corneal and aqueous levels of topically applied trifluorothymidine (F3T) were compared with and without the collagen shield in normal and damaged rabbit eyes. Shields were presoaked in 1% F3T for 15 minutes prior to application. Rabbits received either a presoaked shield, 1% F3T drops every two hours, or both. Corneal and aqueous levels of F3T were measured at 30 minutes, two, four, and eight hours. If 5 mm epithelial defects were created, the collagen shield and topical F3T drops produced significantly higher levels of F3T than drops alone at all periods tested (P less than .05). A presoaked shield alone produced greater levels of F3T than drops alone at 30 minutes and two hours (P less than .05). Collagen shields did not enhance F3T levels in eyes with intact epithelium. Implications for treatment of herpetic keratouveitis are discussed.

Contrast sensitivity in extended wear of the Boston IV lens.

Over a one-year period we evaluated subjective and objective factors associated with extended wear of Boston IV rigid gas permeable contact lenses. Patients wore the lens on an extended wear schedule, with removal at 2-week intervals for cleaning. We performed keratometry and endothelial cell counts and measured visual acuity, contrast sensitivity, refraction, and corneal thickness at the initial visit (with patients wearing their former glasses or soft or hard lenses) and again at 6 and 12 months (with patients wearing the Boston IV lens). Twenty-four of 31 patients (77%) completed the study. All measured parameters were checked for statistically significant change over time. Contrast sensitivity increased at all spatial frequencies tested, with the largest increments occurring at higher frequencies (P less than .001). The other parameters showed no significant changes (P greater than .05). Our data support the use of contrast sensitivity for qualitative assessment of visual function among contact lens wearers and suggest that contrast sensitivity testing may prove to be a more effective means of evaluating visual acuity in contact lens wearers over time than Snellen acuity.

Clinical evaluation of three bifocal contact lenses.

The ACC, Alges, and Tangent Streak bifocal contact lenses were fit in separate populations of presbyopic patients, some of whom had not previously worn contact lenses. Complete eye examinations were performed on fitting and at 6 and 12 months after fitting to determine how effectively the lenses corrected presbyopic symptoms. Patients were examined for subjective comfort, visual acuity, contrast sensitivity, and by slit lamp. Sixteen of the 24 ACC lens wearers (67%), 23 of 31 Alges lens wearers (74%), and 25 of 27 Tangent Streak lens wearers (93%) wore their lenses comfortably after 12 months. Nine of 18 failures (50%) were successfully refit in one of the other bifocal lenses. Most patients read 20/25 and J1 with contrast sensitivity in the normal range at distance and near. Twelve of 16 patients (75%) with no prior contact lens experience continued to wear the lenses at 12 months. We believe that bifocal contact lenses provide an acceptable alternative for the correction of presbyopia. Lens fitting requirements and patient selection are discussed.