It’s in the Bag
ESCRS Heritage Lecture explores the enigma of the anterior hyaloid.
Published: Thursday, February 1, 2024
The anterior hyaloid has remained a matter of controversy since its earliest description in terms of its relationship with other parts of the intraocular anatomy, its strength, and its distinction from the posterior capsule. Research now confirms its actual nature and role in separating the anterior segment from the vitreous cavity, said Marie-José Tassignon MD, PhD in her Heritage Lecture at the 2023 ESCRS Congress in Vienna.
“Most illustrations tend to leave out the anterior hyaloid,” she noted. “But it is important because the anterior hyaloid is the membrane that separates the anterior segment from the posterior segment. And it is not the posterior capsule.”
Descriptions of the anterior hyaloid date back to the late nineteenth century, possibly the eighteenth. The hyalo-capsular ligament—“Wieger’s ligament”—that fastens the anterior hyaloid to the periphery of the posterior lens capsule was first demonstrated by Germain Wieger in 1883. In his 1887 medical thesis, Emil Berger created anatomical illustrations of the space between the anterior hyaloid and the posterior capsule, now known as Berger’s space (BS).1, 2
However, textbooks continued to describe Berger’s space as somehow “virtual” in nature. Professor Tassignon noted that in 1999, Jan Worst invited her to Groningen, Netherlands, to collaborate in research demonstrating it possible to use a staining technique to visualise BS. Further research conducted with the fluorophotometer (Fluorotron) developed by José Cunha-Vaz showed fluorescein injected into the anterior chamber primary posterior capsulorhexis did not diffuse into the vitreous so long as there was no damage to the anterior hyaloid.
Prof Tassignon noted the presence of Berger’s space can also be easily demonstrated by gently puncturing the posterior capsule with a lateral capsule-dragging approach and injecting an ophthalmic viscosurgical device underneath. If the anterior hyaloid is intact, the OVD will spread homogeneously until it reaches Wieger’s ligament. In addition, Prof Tassignon and her associates were able to demonstrate the presence and dimensions of BS and the anterior hyaloid face intraoperatively using an optical coherence tomography (OCT) system attached to the Opmi Lumera 700/Rescan microscope (Zeiss).3
These findings were important in confirming the safety of Prof Tassignon’s bag-in-the-lens (BIL) intraocular lens (IOL). Designed to prevent posterior capsule opacification, the lens is implanted after posterior capsulorhexis for implantation and clasps the anterior and posterior capsule in a groove between its plate-like haptics.
“Based on all these accumulations of knowledge, we were able to implement the ideal adult BS dimensions in the ideal Gullstrand eye model, which should be 8.0 mm to 9.0 mm,” Prof Tassignon said. “Definitely big enough to accommodate a lens of 7.5 mm, and that is why the diameter of the BIL is 7.5 mm.”
She added that while she has not conducted comparative studies, the BIL does not appear to endanger the retina. She has observed no excess in retinal detachment, and among normal eyes with no ocular nor systemic comorbidity factors implanted with the lens, there have been no instances of macular oedema.
She also noted that as a patient ages, their eyes become increasingly prone to anterior vitreous detachment, just as with posterior vitreous detachment. This can be demonstrated by a “spaghetti-like” diffusion of OVD injected beneath the posterior capsule.
A pathology of the hyaloid and posterior capsule, called anterior vitreolenticular interface dysgenesis (AVLID), appears to play a role in paediatric cataract, Prof Tassignon said. The condition arises from a repair mechanism from the lens epithelial cells in the capsular bag and the hyalocytes from the vitreous face that transform into fibroblasts, creating opaque plaques.
“In such cases, one option is to place the anterior capsule, anterior hyaloid, and posterior capsule within the groove of the lens, restoring the kind of attachment of the anterior hyaloid as it is in nature,” she added.
For citation notes, see page 48.
Marie-José Tassignon MD, PhD, FEBO is emeritus chair and chief of the department of ophthalmology at the University Hospital of Antwerp, Belgium. She is a past president of the ESCRS.