Lens Subluxation: “Zonular-Fibre-Attachment-To-Limbus Distance” (Z L D) As A Novel Diagnostic Parameter

To date, there is no established criterion to diagnose subluxation of the lens. This prospective study investigated the distance between the zonular fibre attachment and the limbus (ZLD) in 150 healthy volunteers using a new method. The normal values can serve to diagnose and quantify lens subluxation, which currently is a subjective diagnosis requiring standardization.

Healthy volunteers participated this non-invasive clinical study at the Eye Clinic of Charité – Medical University Berlin, Campus Virchow Clinic.

150 eyes of 150 subjects (average age 28 years, range 4-68 years) were included. Pupils were dilated with tropicamide 0.5% and phenylephrine 2.5% instilled twice 5 minutes apart in all but 4 subjects, who received only one drop. The ZLD was measured at the slit lamp as the distance between the insertion of the zonular fibres on the lens surface and the limbus. Vertical pupil diameter (PD) and refractive errors were also recorded. 145 right and 5 left eyes were examined. In most subjects, the ZLD was also measured photographically.

Zonular fibres could be visualised in 76 of 150 subjects, ZLD was 1.29±0.29 mm (mean±SD), range 0.7-2.1 and mean PD 8.79±0.58 mm (7.5-9.8). In 74 subjects, in whom the insertion of zonular fibres could not be seen, the distance between limbus and pupil margin was measured as a surrogate for the ZLD. In those, mean ZLD was 1.38±0.28 mm (0.7-2.1) and mean PD 8.13±0.58 mm (6.7-9.4). For all subjects (n=150) mean ZLD was 1.34±0.29 mm (0.7-2.1) and mean PD 8.47±0.66 mm (6.7 to 9.8). 

Average ZLD was 1.3 mm in normal subjects. Although in myopic eyes the pupil dilated more, refractive error did not have significant effect on ZLD. The normative data from this study can serve clinically and scientifically to diagnose and quantify lens subluxation.