Meibomian gland status comparison between active duty personnel and U.S. Veterans

Military Medicine, Aug 2000 by Molinari, Joseph F

Purpose: To evaluate the lid and meibomian gland status of active duty forces (ADF) and U.S. veterans (USV) to compare the prevalence of lid dysfunction and disease in each population. Methods: One examiner observed 113 consecutive patients in both groups during a 2-week period at two federal service optometry clinics. All eyes were graded with regard to negative findings (or normal), meibomian gland dysfunction (MGD), and/or meibomitis from an established criterion. Resuits: 90.36 of ADF had normal lid findings, 5.3% of ADF had MGD (all contact lens patients), and 4.496 of ADF had meibomitis; 28.996 of USV had normal findings, and 71.196 of USV had MGD or meibomitis (no patients wore contact lenses). Conclusion: Our findings reveal that a definite difference exists between ADF personnel and USV in eyelid physiology and pathophysiology. This difference should be noted by the clinician who evaluates such patients. This will affect the differential diagnosis of ocular symptomatology in the contact lens and non-contact lens patient.

Introduction

Although the meibomian glands were first discovered in 1666 by a German physician, Meibomius,1 it has only been in the last 20 years that researchers and clinicians have explored the anatomy, function, physiology, and pathophysiology of these ducted glands. Like other sebaceous glands, they are holocrine glands and secrete oil to the free border of the eyelid margin, allowing retention of the normal lacrimal secretion on the eye. Most importantly, these glands contribute to the composition of tears and precorneal lacrimal film.1-4 There have been many studies in the last 20 years describing meibomian glands and their impact on dry eye, contact lens wear, blepharitis, keratitis, and systemic skin problems.5-19 In 1990, Horn et al. reported the prevalence of meibomian gland dysfunction (MGD) as 38.9% in individuals other than 50 years of age.20 These investigators also found a highly significant positive correlation of MGD and age.20 They felt that with the upright posture of humans, gravity will eventually hinder the flow of sebum from the meibomian glands of the lower lid. This impediment of sebum flow with stenosis of the gland duct reduces the amount of sebum at the orifice on the lid margin, thus reducing the amount of sebum in the tear film of the eye and decreasing the tear layer volume on the eye. With this reduction, the aqueous volume portion of the tear is then compromised by an increased evaporation rate that can lead to a dry eye condition.21.22

The purpose of our study was to evaluate the lid and meibomian gland status in two distinct populations, active duty forces (ADF) and U.S. veterans (USA, and to compare the prevalence of lid dysfunction and disease in each population. This was done by having an experienced clinician examine 113 consecutive patients of both groups with a biomicroscope, evaluating them with a set diagnostic criteria, and then calculating the results and comparing the two populations.

Methodology

One examiner observed 113 consecutive patients in both groups of patients during a 2-week period at two federal service optometry clinics in the same region. The first group, ADF, were seen at the Optometry Clinic, 96 Medical Group at Eglin Regional Hospital, Eglin Air Force Base, Florida. This group had a mean age of 23.2 years and 89.3% male composition. The second group was observed at the Veteran Health Affairs Outpatient Clinic in Tallahassee, Florida. This group had a mean age of 68.1 years and 99.2% male composition. All eyes were graded in three categories-normal, MGD, and meibomitis-from the established criteria listed in Table I.

The results of the clinical observations during routine eye evaluations were recorded in clinical records. Biomicroscopic evaluation included observation of the lid, corneal, and conjunctival surfaces with 18x magnification for evidence of compromise. Gland secretions were observed with and without applying firm digital pressure against the lid margin directly under the lash margin. The background of the pupil and iris allowed for viewing of the expressed material on the anterior segment of the eye. The procedure was repeated if no expression was noted on the first try (Fig. 1).

Results

For the ADF patients, 90.3% had normal lid findings, 5.3% had MGD, and 4.4% had meibomitis. All of the individuals in the latter two subgroups were contact lens wearers. For the USV group, 71.1% had MGD or meibomitis and none wore contact lenses. The USV group had 28.9% normal lid findings with 14.2% MGD and 56.9% meibomitis.

Discussion

This study supports the conclusions of Horn et al. that older patients seem to have more problems with meibomian glands than a younger non-contact lens-wearing population.20 The criterion for objective clinical signs for MGD in the Horn et al. study was cloudy or absent secretion upon expression. From this model, the authors showed that the percentage prevalence of MGD increased with decade of age. Patients in the younger age group of 29 years and younger had a prevalence of 33%, whereas patients older than 60 years of age had a prevalence of 67.2%. In the former group, more than two-thirds of the patients wore contact lenses of various types. These findings are similar to our findings in terms of the combination of MGD and meibomitis; however, our younger population had fewer contact lens wearers.