Patients with progressive supranuclear palsy (PSP) and patients with Parkinson disease frequently manifest signs of dry eyes, yet many remain asymptomatic. In this study, we established the relationships between blink rate, corneal sensitivity, and corneal nerve density in patients with ocular surface disease associated with PSP and Parkinson disease.
Fourteen eyes of 7 patients with PSP, 8 eyes of 4 patients with Parkinson disease, and 10 eyes of 5 age-matched controls were examined for meibomian dysfunction, ocular surface staining, and blink rate. Corneal sensitivity was measured with a Cochet-Bonnet esthesiometer, and corneal subbasal nerve density was measured by using confocal microscopy in vivo. Comparisons between variables were assessed by using generalized estimating equation models to account for possible correlation between fellow eyes of the same subject.
Abnormal ocular surface staining and meibomian disease were present in most subjects with PSP and Parkinson disease, but in none of the controls. Patients with PSP and Parkinson disease had lower blink rates (P < 0.001) and decreased corneal sensitivity (P < 0.001) compared with controls, whereas subbasal nerve density did not differ between groups. Blink rate was correlated with corneal sensitivity (r = 0.83, P < 0.001), but corneal sensitivity was not correlated with subbasal nerve density (r = -0.16, P = 0.78).
Patients with ocular surface disease associated with PSP and Parkinson disease might be asymptomatic because of decreased corneal sensitivity. Decreased corneal sensitivity was not explained by loss of corneal nerves but was associated with decreased blink rate.
"Parkinson's disease, for example, has an incidence of 13.4 per 100,000; only 4% of the cases occur in patients younger than 50 years . Patients with Parkinson's disease have lower blink rates compared with controls . In Parkinson's patients, dopaminergic dysfunction is thought to play a role in decreasing the blink reflex that leads to dry eyes. "
[Show abstract][Hide abstract] ABSTRACT: Dry eye syndrome is a disease of the ocular surface and tear film that is prevalent in older adults. Even though the degree of visual acuity loss in dry eye patients is commonly mild-to-moderate, in the aging population, this minimal change in visual status can lead to a significant decrease in visual function and quality of life. A healthy ocular surface is maintained by appropriate tear production and tear drainage, and deficiencies in this delicate balance can lead to dryness. In the aging eye, risk factors such as polypharmacy, androgen deficiency, decreased blink rates, and oxidative stress can predispose the patient to developing dry eye that is frequently more severe, has higher economic costs, and leads to worse consequences to the well-being of the patient. Understanding why elderly patients are at higher risk for developing dry eyes can provide insights into the diagnosis and management of the growing number of older adults struggling with dry eye and minimize the burden of disease on our aging population.
Journal of Ophthalmology 08/2014; 2014:781683. DOI:10.1155/2014/781683 · 1.43 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To investigate the effect of benzalkonium chloride (BAK) on corneal nerves.
Fifty-four adult New Zealand Albino rabbits were randomly divided into 3 groups. BAK at concentrations of 0.005%, 0.01%, or 0.02% was applied once daily to 1 eye of each rabbit for 9 days. The contralateral untreated eyes were used as controls. Corneal mechanical sensitivity, aqueous tear production, tear break-up time (BUT), fluorescein, and Rose Bengal staining scores were compared with those of control values on days 3, 6, and 9. Corneal whole mounts were immunostained with a specific antitubulin βIII antibody to label nerve fibers. Epithelial superficial nerve terminal, subbasal, and stromal nerve fiber densities were quantified. The structure of the central cornea was examined by means of in vivo confocal microscopy on day 9.
The topical application of BAK resulted in lower corneal sensitivity and higher Rose Bengal staining scores on day 3, whereas there were no significant changes in the BUT, Schirmer, and corneal fluorescein scores. Decreased nerve densities in superficial and subbasal layers were observed in BAK-treated eyes on days 3 and 6, respectively. The eyes treated with 0.02% BAK exhibited significantly reduced Schirmer scores, BUT, and stromal nerve fiber density, and increased fluorescein staining scores on day 9. Corneal superficial epithelial cell size was significantly larger in all BAK-treated eyes compared with that in control eyes.
The topical application of BAK can quickly cause corneal hypoesthesia without tear deficiency. Changes in corneal innervation significantly correlate with BAK-induced ocular surface changes.
[Show abstract][Hide abstract] ABSTRACT: To investigate the changes of the corneal microstructure of neurosurgically-induced neurotrophic keratitis patients compared to normal human corneas using in vivo confocal microscope (IVCM).
Journal of the Korean Ophthalmological Society 01/2014; 55(12):1765. DOI:10.3341/jkos.2014.55.12.1765
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