I know what you’re thinking. You’re thinking that I’m going to write about optic neuritis since this is what everyone writes about. But, you will be wrong. This post is about the lesser well known portion of the eye – the conjunctiva.
In a small cross-sectional study of MS patients and controls, a group of investigators from Turkey have found that dry eyes are far commoner in MS than you’d expect by chance. The Schirmer test was below 10mm in 66.7% of the participants, whilst the TBUT was below 10s in 81.8% of MS patients. On average the Schirmer test result was 8.45mm in MS vs 17.36mm in controls and the TBUT was 8.12s vs 13.06s in controls.
As a result, on corneal biopsies showed that the degradation of the cornea was greater in MS; with 33% demonstrating grade 2 scores and 9.1% demonstrating grade 3 scores (see figure below).
It is thought that the dry eyes occur as a result of reduced corneal nerve innervation to the eye. In addition to providing sensation to the cornea, they provide growth support as well. With a reduction in the corneal nerve fibre density there is an obvious reduction in the health of the cornea.
Conjunctival impression cytology and tear film parameters in patients with multiple sclerosis
Purpose: To evaluate conjunctival impression cytology (CIC) findings and tear film parameters in patients with multiple sclerosis (MS) compared with controls.
Methods: Thirty-three patients with MS (MS group) and 33 age- and sex-matched healthy subjects (control group) were included in this cross-sectional comparative study. CIC grades, tear break-up time (TBUT), Schirmer 1 test results, and Ocular Surface Disease Index (OSDI) scores were compared between the two groups, and correlations between CIC grade, TBUT, Schirmer 1 test result, OSDI score, Expanded Disability Status Scale score, and disease duration were analyzed.
Results: Mean CIC grade was higher in the MS group than in the control group (1.48 ± 0.71 and 0.39 ± 0.56, respectively; p < 0.001). In the MS group, CIC of the 14 participants (42.4%) was grade 2-3. In the control group, CIC of the only one participant (3.3%) was grade 2, and none of them was grade 3. TBUT (8.12 ± 3.16, 13.06 ± 4.23 s in MS and control groups, respectively; p < 0.001) and Schirmer 1 test results (8.45 ± 5.75, 17.36 ± 10.89 mm in MS and control groups, respectively; p < 0.001) were lower, and OSDI score (36.36 ± 19.19, 13.70 ± 15.36 in MS and control groups, respectively; p < 0.001) was higher in the MS group compared to the control group.
Conclusion: In patients with MS, objective findings of dry eye, subjective symptoms related to dry eye, and CIC abnormalities, including high grades of conjunctival squamous metaplasia and goblet cell loss, are more common. Patients with MS should be monitored for ocular surface alterations and dry eye disease.