Morphological study of the accommodative apparatus in the monkey eye

The Relationship Between the Change of Intraocular Lens Position and Capsular Bend After Cataract Surgery

PURPOSE

To explore the relationship between the change in intraocular lens (IOL) position and capsular bend after cataract surgery.

METHODS

Patients underwent phacoemulsification and IOL implantation (Alcon Laboratories, Inc). Patients were divided into two groups based on preoperative axial length: long axial length group (axial length ⩾ 26 mm) and normal axial length group (axial length > 22 but < 26 mm). Swept-source optical coherence tomography was performed at 1 day, 1 week, 1 month, and 3 months after mydriasis to obtain postoperative aqueous depth (PAD) and capsular bend index (CBI). The relationship between CBI and PAD changes was analyzed.

RESULTS

Eighty patients (80 eyes) were included in the study. PAD decreased gradually from 1 day to 1 week and increased from 1 week to 3 months. Mean CBI was moderately positively correlated with PAD changes (r = 0.586, P < .001). The IOL moved forward gradually when the CBI was less than 2.30 and the IOL gradually moved backward when the CBI was 2.30 or greater. The root mean square of the change in PAD was smaller in the long axial length group (0.08 ± 0.04 mm) than in the normal axial length group (0.09 ± 0.05 mm) during the 3 months after surgery (P = .036).

CONCLUSIONS

The position of the IOL was almost stable 1 month after operation, and postoperative capsule adhesion mainly occurred within 1 month. The change in PAD was related to capsule adhesion. The postoperative position of the IOL was relatively stable and capsular bend was relatively slow for the long axial length group over 3 months. [J Refract Surg. 2021;37(5):324-330.].

Anteriorly located zonular fibres as a tool for fine regulation in accommodation

PURPOSE

To describe an anteriorly located system of zonular fibres that could be involved in fine-tuning of accommodation.

METHODS

Forty-six human and 28 rhesus monkey eyes were dissected and special preparations were processed for scanning electron microscopy and reflected-light microscopy. Additional series of frontal and sagittal histological and ultrathin sections were analysed in respect to the origin and insertion of anteriorly located zonules. The presence of sensory terminals at the site of the originating zonules within the connective tissue of the ciliary body was studied by immunohistochemistry. For in-vivo visualization ultrasound biomicroscopy (UBM) was performed on 12 human subjects.

RESULTS

Fine zonular fibres originated from the valleys and lateral walls of the most anterior pars plicata that covers the anterior and inner circular ciliary muscle portion. These most anterior zonules (MAZ) showed attachments either to the anterior or posterior tines or they inserted directly onto the surface of the lens. At the site of origin, the course of the MAZ merged into the connective tissue fibres connecting the adjacent pigmented epithelium to the ciliary muscle. Numerous afferent terminals directly at the site of this MAZ-origin were connected to the intrinsic nervous network of the ciliary muscle.

CONCLUSIONS

A newly described set of zonular fibres features the capabilities to register the tensions of the zonular fork and lens capsule. The close location and neural connection towards the circular ciliary muscle portion could provide the basis for stabilization and readjustment of focusing that serves fast and fine-tuned accommodation and disaccommodation.