Gout is a lesser-known risk factor for dry eye disease, yet this inflammatory arthritis is increasing in prevalence along with an aging population. Clinicians may potentially find dilated conjunctival vessels in patients with gout, as well as symptoms caused by subclinical ocular presence of monosodium urate crystals (MSU). A recent case-control investigation uses both objective tests and questionnaires to analyze tear function in those with this complex inflammatory disease, according to data published in Eye & Contact Lens.
Minimally invasive conjunctival impression cytology (CIC) was used to determine epithelial cell makeup in 66 participants, mean age 51.18 years: 34 patients diagnosed with gout and 32 sex- and age-matched healthy individuals. Tear function was evaluated with Schirmer I test and tear break-up time (TBUT). Dry eye symptoms were gauged using the Ocular Surface Disease Index (OSDI). Investigators also performed anterior segment and fundus examinations with a slit lamp.
CIC biopsy evaluates goblet cell density and presence of squamous metaplasia in a patient’s conjunctival epithelium, thus revealing health of the ocular surface. It is graded from 0 to 3, with grades 2 and 3 signifying abnormal cell changes. A significant difference was found between the case group which scored a CIC mean grade of 1.15, with the control group at 0.47 (P <.001). Ten participants with gout had a CIC grade of 2 or 3, although no healthy individuals obtained grade 2 or 3.
TBUT also showed significant differences: 88.2% of the case group experienced break-up time under 10 seconds, compared with 21.9% in the control group. “The high rate of patients with low TBUT suggests that tear stability is particularly affected in patients with gout,” the analysis noted. Mean break-up time was 7.00 seconds in case participants, and 12.75 seconds for those in the healthy cohort (P <.001).
Differences also arose using Schirmer 1 testing, with mean tear-soaked strip length of 9.74 mm in the case group and 17.16 mm in the control group (P <.001). Subjective perception of dry eye symptoms was higher in case individuals — mean OSDI score for those with gout was 20.04, and 6.19 in healthy participants (P <.001).
With uric acid excess, the MSU crystals can build up in a patient’s joints, as well as tissues outside the joints. MSU crystals have been detected in periocular and ocular regions, but how often they occur undetected by typical clinical tests is still unknown. This analysis speculates the eye has “low solvent ability” for MSU, and a lower temperature.
The study comprised a 32.4% female, 67.6% male gout cohort, and 31.2% female, 68.8% male control group.
Limitations of the research included a somewhat small sample size, and cross-sectional design. However, this is the first investigation to demonstrate changes such as conjunctival goblet cell loss in those with gout, according to the analysis. “Because studies on ocular surface findings in patients with gout are limited, the awareness of clinicians on this issue should be increased,” the researchers suggest.
Belviranli S, Turk HB, Oltulu P, et al. Tear function alterations and conjunctival impression cytology findings in patients with gout. Eye Contact Lens. Published online August 20, 2021. doi:10.1097/ICL.0000000000000832