Tear production and corneal sensitivity in diabetes

Tear film and ocular surface changes in diabetes mellitus

“…sient visual acuity reduction due to tear film instability may be also present (43) . The most frequent and measurable clinical findings are reduced tear secretion, tear film instability, higher grade of conjunctival squamous metaplasia, lower goblet cell density and reduced corneal sensation, but diabetes mellitus also reduces the lipid layer of the tear film (4)(5)40,44) . The correlation between diabetes mellitus duration or diabetic retinopathy and diabetic complications in the ocular surface is controversial in the medical literature (5,42,45) .…”

Optical quality of the diabetic eye: a review

“…[16][17][18][19][20][21][22][23][24][25][26] Some ocular manifestations of DM are associated with lachrymal gland dysfunction and have been related to dry eye. Several clinical studies have demonstrated that people with DM are more vulnerable to dry eye than healthy subjects.…”

“…[16][17][18][19] In people with DM, the most frequent and measurable alterations of the tear film function are reduced tear secretion, [16][17][18][19][20][21][22] tear film instability (tear film break-up time (TBUT)), 17,18,20,21 higher degree of conjunctival squamous metaplasia, [16][17][18]21 lower globet cell density, 17,21 and reduced corneal sensitivity. 17,19,21,22 Although the mechanisms of these changes in the ocular surface with DM are still unclear, some studies suggest that diabetic neuropathy affects the innervation of the lachrymal gland and that the fluctuation in the glycaemic control could affect the ocular surface and lachrymal gland secretory function, causing a decrease in basal tear secretion and TBUT. 17,20,21 However, other studies showed that basal tear secretion and TBUT values do not change, but total and reflex tear secretions are significantly reduced in subjects with DM, suggesting that the decreased reflex tearing is due to a diminished sensitivity in cornea and conjunctiva.…”

“…29,40 Regarding endothelial cell hexagonality loss (pleomorphism), some authors reported a decrease in the percentage of hexagonal cells. 37,40 A number of studies have shown that people with DM have decreased corneal sensitivity, 17,19,21,22,27,28,33 make them more vulnerable to corneal trauma. Thickening and thinning of Schwann cell basal lamina, irregular distribution in the nerve beading pattern, and occasional axonal degeneration of the nonmyelinated corneal nerves have been found in people with DM.…”

“…86,87 Even though there are no studies evaluating the impact that these factors could have on HOAs in people with DM, these do have a thicker and more convex lens, [54][55][56] can develop premature cataracts, [9][10][11] and suffer a series of changes associated with lachrymal gland dysfunction and dry eye syndrome. [16][17][18][19][20][21][22][23][24][25][26] Patients with DM who undergo laser-assisted in situ keratomileusis are also at a significantly higher risk of developing postoperative epithelial complications, and refractive results tend to be worse compared with healthy people. 88 Few authors have investigated HOAs in people with DM.…”