Implementation of a vision-screening program in rural northeastern United States

BACKGROUND

Rural populations comprise almost 20% of the US population and face unique barriers in receiving health care. We describe the implementation of a medical student-run free vision-screening clinic as a strategy to overcome barriers in accessing eye care in New Hampshire and Vermont.

METHODS

Medical students were trained by an ophthalmologist to administer screening eye examinations. Patients from New Hampshire and Vermont were enrolled through a free community clinic. Screening included a questionnaire, distance and near visual acuity, extraocular movements, confrontational visual fields, and Amsler grid. Patients who met predetermined screening criteria were referred to an ophthalmologist or optometrist for further evaluation. Data including patient demographics, appointment attendance, level of education, and diagnoses were recorded and analyzed.

RESULTS

Of 103 patients (mean age of 45.5±12.3 years, 63% female), 74/103 (72%) were referred for further evaluation, and 66/74 (89%) attended their referral appointments. Abnormal ophthalmologic examination findings were observed in 58/66 (88%) patients who attended their referral appointment. Uncorrected refractive error was the most common primary diagnosis in 38% of referred patients. Other diagnoses included glaucoma suspect (21%), retinal diseases (8%), amblyopia (8%), cataract (6%), others (6%), and normal examination (12%). Of the 8/74 (11%) referred patients who did not attend their appointments, reasons included patient cancellation of appointment, work conflicts, or forgetfulness. Patients traveled a mean distance of 16.6 miles (range: 0-50 miles) to attend screening examinations. Mean time for patients' last effort to seek eye care was 7.1 years (range: 1-54 years).

CONCLUSION

This study underscores the high prevalence of unmet eye care needs in a rural population. Furthermore, it demonstrates that using community health centers as a patient base for screening can yield a high referral attendance rate for this at-risk population and facilitate entrance into the eye care system in a rural setting.

Visual contrast sensitivity in Alzheimer's disease, mild cognitive impairment, and older adults with cognitive complaints

Deficits in contrast sensitivity (CS) have been reported in Alzheimer's disease (AD). However, the extent of these deficits in prodromal AD stages, including mild cognitive impairment (MCI) or even earlier, has not been investigated. In this study, CS was assessed using frequency doubling technology in older adults with AD (n = 10), amnestic MCI (n = 28), cognitive complaints without performance deficits (CC; n = 20), and healthy controls (HC; n = 29). The association between CS and cognition was also evaluated. Finally, the accuracy of CS measures for classifying MCI versus HC was evaluated. CS deficits were found in AD and MCI, while CC showed intermediate performance between MCI and HC. Upper right visual field CS showed the most significant difference among groups. CS was also associated with cognitive performance. Finally, CS measures accurately classified MCI versus HC. The CS deficits in AD and MCI, and intermediate performance in CC, indicate that these measures are sensitive to early AD-associated changes. Therefore, frequency doubling technology-based measures of CS may have promise as a novel AD biomarker.

Anterior Visual Pathway Gliomas: The Last 30 Years

Modern neuroimaging provides excellent characterization of anterior visual pathway gliomas, often obviating the need for biopsy of the tumor. Management remains controversial, but if there is progression, chemotherapy is preferred for young patients. Stereotactically guided conformal radiotherapy and proton beam radiotherapy allow smaller, more precise doses of radiation to be administered and can be considered in older children with progressive disease. A mouse model of NF-1 with optic pathway gliomas has the potential to provide important insights into the development of gliomas as well as serving as a model for their effective treatment.

Ocular pathologic findings of neurofibromatosis type 2

OBJECTIVE

To gain insight into the pathogenesis of neurofibromatosis type 2 (NF2) by investigating the ocular manifestations of this disease.

METHODS

Using standard histologic techniques, immunohistochemistry, and electron microscopy, we described the ocular pathologic findings of a 34-year-old woman who died from complications of NF2.

RESULTS

We identified 3 types of NF2-associated lesions: juvenile posterior subcapsular cataracts, epiretinal membranes, and an intrascleral schwannoma.

CONCLUSIONS

Our analysis indicated that dysplastic lens cells accumulate just anterior to the posterior lens capsule in juvenile posterior subcapsular cataracts and that dysplastic Müller cells may be a major component of NF2-associated epiretinal membranes. Clinical Relevance Our findings suggest that a subset of glial cells with epithelial features (Schwann cells, ependymal cells, and Müller cells) may be particularly sensitive to loss of the NF2 gene. Understanding the molecular basis for this sensitivity may lead to novel strategies for treating NF2.

Rapid and slow release phenytoin in epileptic patients at steady state: assessment of relative bioavailability utilizing Michaelis-Menten parameters

The bioavailability of phenytoin from rapid release capsule and oral solution formulations relative to that of a slow release capsule formulation was assessed in five patients who had participated in a three-way crossover study performed at steady state. The subjects then underwent dosage adjustment utilizing the slow release formulation, and estimates of their Michaelis-Menten parameters thus obtained were utilized in calculating the relative bioavailabilities. In addition, expected changes in steady-state plasma phenytoin concentrations were calculated assuming initial levels of 15 mg/liter, with increases and decreases in bioavailability of 10%. The consequences of such alterations in the extent of phenytoin absorption or average content of the dosage form may be clinically significant, particularly where the initial phenytoin level is equal to or greater than the patient's operative Km.

Rapid and slow release phenytoin in epileptic patients at steady state: comparative plasma levels and toxicity

Phenytoin plasma level and toxicity data were compared in a three-way crossover study performed in 18 patients at steady state. Formulations compared were a rapid and a slow release capsule and an oral solution. Plasma concentration-time integrals and maximum plasma phenytoin levels were significantly greater for the rapid release capsule and solution than for the slow release capsule. The incidence of nystagmus and toxicity did not differ for the three treatments, but the occurrence of mental symptoms was more frequent for the oral solution, possibly because of the solvent used in this formulation.