Morphologic Patterns Formed by the Anomalous Fibers Occurring Along the Anterior Capsule of the Crystalline Lens in People With the Long Anterior Zonule Trait

Abstract

People with the long anterior zonule (LAZ) trait, which may have prevalence near 2%, have zonular fibers that extend more central than usual along the anterior capsule of the crystalline lens. The anomalous fibers can be observed in vivo with clinical slit lamp biomicroscopy after pharmacologic pupil dilation, and although minimally studied, the LAZ trait may have importance to glaucoma, retinal degeneration, and cataract surgery. In order to further characterize LAZ morphology, a custom computer program was used to trace LAZ fibers seen on retro-illumination photos acquired during previous study at an academic, urban eye care facility in Chicago, IL, USA. There were 59 African-Americans (54 female; median age=70 years, 53–91 years) included in the analysis. After initial review of the zonule tracings, we identified three basic LAZ patterns. We called one pattern (47% of right eyes) a “non-segmental LAZ pattern,” which was predominated by fibers that could be visually traced to the dilated pupil border where they became obscured by the iris. Another pattern (35% of right eyes), the “segmental LAZ pattern,” was predominated by fibers that appeared to terminate abruptly without detectable extension to the pupil border. The third pattern (18% of right eyes), the “mixed LAZ pattern,” had a more equivalent mixture of the other two fiber morphologies. Compared to the “non-segmental” group, the “segmental” LAZ eyes had smaller central zonule-free zones (P<0.0001), and they tended to exhibit fewer LAZ fibers (P=0.07). These data improve understanding of LAZ clinical anatomy and may be helpful to future investigation.

Krukenberg’s Spindles Strongly Suggest Long Anterior Zonule Associated Pigment Dispersion Mechanism in Older Patients

“…In prior investigations, we have quantified LAZ in terms of number of detectable fibers by clock hour, zonule-free zone size, and LAZ pattern type. 26,35 Determining these parameters, which required detailed photographic documentation, could not be done in the current study. Future work may show whether these factors have any relationship to KS.…”

“…34 Further detail on LAZ morphology and detection is presented elsewhere. 11,20,26,35 To ensure definitive LAZ cases, we excluded subjects with < 5 LAZ fibers. 20,26,35 To provide estimation of the number/density of LAZ, investigators used the following arbitrary scale based on countable LAZ fibers: grade trace = 0 to 4, grade 1+ = 5 to 9, grade 2+ = 10 to 19, grade 3+ = 20 to 49, and grade 4+ = ≥ 50.…”

Research progress of lens zonules

“…During slit-lamp examination, the LAZs are observed as fine, radially oriented fibers on the anterior capsule, extending more central than usual along the anterior lens surface. 48 A significant correlation was found between LAZ and mild elevated intraocular pressure, 49 suggesting that the existence of LAZ might increase the risk of glaucoma. Khurana et al.…”

Long anterior lens zonules with retinal stripes: a case report

“…It sometimes causing a marked reduction in the ZFZ diameter. The estimated prevalence is from 1–2% and is associated with age > 50 years, female sex, and most binocular diseases [ 1 , 2 ]. But previous studies were mostly conducted among African Americans.…”