The Effect of Ocular Demodex Colonization on Schirmer test and OSDI Scores in Newly Diagnosed Dry Eye Patients

Abstract

Objective: To determine whether ocular Demodex colonization results in differences in Schirmer test scores and Ocular Surface Disease Index (OSDI) questionnaire values in individuals with dry eye disease (DED) diagnosed for the first time. Method: Eighty-eight adults aged 40 to 68 years who were admitted to Ophthalmology outpatient clinic for routine ophthalmological examination or presbyopia examination and diagnosed with DED for the first time and who do not have any chronic disease were included in the study. All the patients were asked to complete the OSDI, which is widely used for assessing dry eye symptom severity and vision-related functioning. The Schirmer test was performed, and then two eyelashes were taken from the inferior eyelids of each eyes. After saline (0.09% NaCl) was added to the sample, it was quickly taken to the microbiology laboratory, which is located next to the Ophthalmology policlinic. The sample was evaluated by a parasitologist experienced in Demodex. Results: One hundred sixty-eight eyes of 84 patients were included in the study. Average Schirmer test score was 2.1±0.5, the OSDI questionnaire score was 61.82±10.95, and the mean age was 55.36±8.74 years in patients who had Demodex colonization (n=30), whereas the average Schirmer test score was 6.6±0.9 score, OSDI questionnaire score was 40.96±12.73, and the mean age was 49.12±6.87 years in patients without Demodex colonization (n=58). It has been observed that dry eye patients with Demodex colonization had a higher mean age (P: 0.001), higher mean OSDI score (P: 0.001), and lower average Schirmer test score (P: 0.001) compared with those without Demodex. The significant relationship between lower Schirmer test score and higher OSDI rates and occurrence of Demodex infestation continued after adjusting for mean age values (P=0.012; P=0.035). Conclusion: It was determined that the presence of ocular Demodex colonization was associated with the average Schirmer test scores, OSDI scores, and age values in patients with newly diagnosed DED. Demodex quantity was found increased in older aged patients, but the significant relationship between lower Schirmer test score and higher OSDI rates and Demodex infestation persisted even after controlling the mean age values. Supporting these findings with large-numbered and randomized-controlled studies will help in clarifying the association of the Demodex infestation with etiopathogenesis of dry eye.

Age differences in ocular demodicosis: Demodex profiles and clinical manifestations

“…We wondered whether young patients are more susceptible to corneal involvement than elderly patients. However, other studies that mostly included elderly patients have shown that the most common clinical features are MGD and eye dryness with predominantly D. folliculorum (15)(16)(17)(18)(19)(20).…”

Ocular Demodex: a systematic review of the clinical literature

“…84 Li et al 65 reported ocular Demodex to be less prevalent in people with aqueous-deficient dry eye disease, diagnosed using a tear clearance diagnostic test, relative to those without the condition. However, two studies have found no relationship between ocular Demodex density and Schirmer test scores (Lee et al 29 ; Chanlalit et al 33 ) and, in contrast, Ayyildiz et al 54 recently reported that ocular Demodex colonisation was associated with significantly poorer Schirmer test scores. These apparently divergent findings may relate to differences in the study populations, including the duration and severity of dry eye disease, the criteria used to diagnose the condition and the method(s) used to define the presence of Demodex.…”

Demodex and eye disease

“…Although Demodex infestation can present with little to no symptoms, there are co-morbidities that have been associated with its presence, such as blepharitis, 49,[72][73][74] meibomian gland dysfunction (MGD), 69,72,75,76 keratitis, 72,77 blepharokeratoconjunctivitis, 56 chalazion, 55,72,78 dry eye, 79 and pterygium. 80 The risk of Demodex in patients with blepharitis is 2.5-fold, while the risk in rosacea patients is threefold higher than in the general population.…”

“…94,101 Others have shown that the Schirmer test is reduced and the OSDI score is greater in dry eye patients with Demodex. 79 Other studies have used corneal and conjunctival staining, osmolarity, meibum expression and matrix metalloproteinas-9 levels, as outcome measures with conflicting relationships to demodicosis. 37,56,65,112,125,136,151,152 Clearly, there are no well-established correlations between Demodex and ocular signs, which mirrors the challenges encountered for studies in dry eye disease.…”