Structural features of eyelid connective tissue in patients with primary open-angle glaucoma

Abstract

Purpose

To study the connective tissue (CT) structure of upper eyelid skin of primary open-angle glaucoma (POAG) patients.

Patients and methods

Forty-seven patients aged 47–91 expecting blepharoplasty formed 3 groups: group 1 [16 subjects without POAG, median age 55 years (interquartile range 54–55.5)], group 2 [12 subjects without POAG, median age 73 (72–76.5)], and group 3 [(19 subjects with POAG, median age 74 (70–80.5)]. Age differences between groups 1 and 2 and groups 1 and 3 are significant (p < 0.05). Thermodynamic parameters of skin samples taken during blepharoplasty: Endothermic peak ($T_{d}$, °C) and denaturation enthalpy ($\Delta H_{d}$, J/g of dry weight) were determined using differential scanning calorimetry.

Results

$\Delta H_{d}$ and $T_{d}$ in groups 1–3 were, respectively, 8.41 (7.42–10.25) and 66.55 (59.9–66.7); 7.10 (5.76–10.17) and 67.35 (67.0–68.03); 11.40 (9.0–14.9) and 67.70 (67.05–68.45). $T_{d}$ differences between groups 1 and 2 are significant (p < 0.05), and Spearman’s correlation between the age and $T_{d}$ is direct, medium (R = 0.638) and significant. $\Delta H_{d}$ in group 3 is significantly higher than in group 2. $\Delta H_{d}$ and $T_{d}$ in patients without POAG (groups 1 and 2) and those with POAG (group 3) are, respectively, 7.79 (6.9–10.17) and 66.6 (61.2–67,3); 11.40 (9.0–14.9); 67.7 (67.05–68.45); the respective differences are significant.

Conclusion

Patients without POAG show a significant increase in $T_{d}$ with age, while $\Delta H_{d}$ slightly decreases. In POAG, $\Delta H_{d}$ is significantly higher and $T_{d}$ tends to grow, which may indicate structural changes in eyelid CT (collagen accumulation and cross-linking level rise). Since the upper lid is unaffected by increasing IOP directly, the changes may be viewed as manifestations of systemic CT pathology.