Relevance of relationships between eye structure measurements for risk of anterior chamber angle closure

Aim of the study
To analyze the relationships between eyeball length, anterior chamber depth and lens thickness with respect to age and refractive state and in chronic versus acute angle-closure glaucoma.

Material and methods
40 patients were evaluated: 180 patients with different refractive states and 60 patients with primary angle-closure glaucoma, acute angle closure glaucoma and cataract.

Results
We propose a predictive factor (PF) for anterior chamber angle closure based on ultrasound biometrics. PF = AC / AL / LT × 100. A significant decrease in PF with age was noted in all refractive states. In hypermetropia, PF was significantly lower than in myopia and emmetropia. PF is more sensitive than Lowe’s coefficient towards a tendency for angle closure with respect to age and refractive state. A significant difference in PF was observed between acute angle closure and cataract groups, and between chronic angle-closure glaucoma and cataract groups. Its significance was higher than the significance of Lowe’s coefficient between the respective groups. PF below 2.5 is a significant risk factor of anterior chamber angle closure.

Conclusions
The risk of anterior chamber angle closure is primarily determined by relationships between measurements of eyeball structures (eyeball length, anterior chamber depth, lens thickness). We propose a PF coefficient calculated from these relationships, which reliably predicts the risk of anterior chamber angle closure.