Clinical examination of the crystalline lens by retrocorneal specular microscopy

Confocal microscopy of the in-situ crystalline lens

The fine structure of the in-situ rabbit crystalline ocular lens from the ex-vivo rabbit eye was observed with a confocal scanning laser microscope in the scattered light mode. The images were observed through the full thickness of the cornea and aqueous humour to a depth of 50 microns in the anterior ocular lens. The following structures were observed from optical sections of the ocular lens: two concentric regions of the lens capsule, epithelial cells, lens sutures, and surface and interior regions of individual lenticular fibres. The observed lateral resolution of the microscope objective was degraded by imaging across thick (millimetre) structures. This study shows the feasibility of obtaining high-contrast images of transparent objects across 1.7 mm of ocular tissue (cornea and aqueous humour) using confocal light microscopy.

Cellular reactions on heparin surface-modified versus regular PMMA lenses during the first postoperative month. A double-masked and randomized study using specular microphotography

Specular microscopy was used for investigation of cellular reactions on the intraocular lens (IOL) anterior surface of Heparin surface-modified (HSM) versus regular polymethylmethacrylate (PMMA) lenses (Pharmacia types 700C versus 700B, respectively). The double-masked randomized study included 53 patients investigated at 1 and 4 weeks postoperatively. Giant cells were only found on control lenses and more frequently at 4 weeks. Small cells were found on both lens types, but in a higher frequency on the control lenses. The number of small cells decreased during the first 4 weeks on both the control and HSM lenses. However, those control lenses that had giant cells on their surface showed an increase in the number of small cells during the same time. The results of the current study show that HSM lenses give rise to less postoperative inflammatory cellular reactions than regular PMMA lenses.

Lens-capsule material of human and animal origin, studied by SEM

Lens-capsule material from healthy and cataractous human lenses and from rabbits was collected with specially designed forceps. Subsequently the capsule fragments were fastened, after short pre-fixation, onto a rubber substrate with small stainless steel tacks, to prevent rolling-up of the fragments during the fixation and drying procedure for the SEM. Finally the capsule fragments were studied by SEM. Marked morphological changes, e.g., irregular swelling (like blebs) of the nuclei, formation of deep grooves at the cell borders and complete loss of epithelial cells, were found in the lens capsules obtained from certain cataractous lenses. Differences in capsule thickness were found in pathological capsule material. The imprints (attachment-lines) of the lens-fibres on the epithelial cells were often difficult to visualize.

Cellular invasion on the surface of intraocular lenses. In vivo cytological observations following lens implantation

Cellular growth on intraocular lenses can be observed by using a specular microscope. We examined in vivo the cellular pattern on the surface of implanted lenses during the early postoperative period in 63 patients. In every case inflammatory cells were noted on the lens surface at some point during the observation period. These often showed a spindle-like appearance resembling fibroblasts. The density of the cell population increased during the following days but usually did not exceed 100 cells/mm2. From the end of the first week, multinucleated giant cells may appear. In one case, a patient with a severe postoperative iritis and hypopyon demonstrated an extremely pronounced and long-lasting cellular proliferation.

Specular microscopy of the anterior lens capsule after endocapsular lens implantation

Endocapsular phacoemulsification and complete in-the-bag intraocular lens (IOL) fixation was performed on 77 eyes. Specular microscopy of the anterior lens capsule was performed postoperatively, and the process of anterior capsule opacification after endocapsular cataract surgery was classified. Lens epithelial cells on the inner surface of the anterior lens capsule, facing the optical portion of the IOL, underwent a diffuse fibrosis. In more peripheral areas, where the anterior and posterior capsules were tightly adherent, the regularly proliferating lens epithelial cells retained their polygonal shape. These findings suggest the possibility of retaining the transparency of the anterior lens capsule postoperatively by refilling the capsular bag to apply internal pressure.

An estimate of the human lens epithelial cell size in vivo

There are few previous estimates of the size of the human lens epithelium. In this study the lens epithelium is measured by specular reflex photography with a macro camera. The results are corrected for cornea magnification. One hundred subjects were studied ranging in age from 11 to 75 and including 20 diabetics and 18 subjects with cataract. The results show a range of epithelial cell diameters from 8-21 microns with 97% of the measurements lying in the 9-17 microns range. Pleomorphism is marked. The mean cell size was 12.7 microns. Large differences exist in mean cell size between individuals, but no correlation was found with age, diabetes or cataract.

Clinical results of endocapsular phacoemulsification and complete in-the-bag intraocular lens fixation

Endocapsular phacoemulsification was performed in the Hara Eye Hospital on 77 eyes of 69 patients between October 1984 and January 1986. The age of patients ranged from 52 to 86 years with an average of 71 years. In 71 of 77 eyes, a posterior chamber lens was inserted. The procedure was attempted in 243 eyes and was successfully performed in 77 of them (32%). The causes of failure in 166 eyes were anterior capsule rupture in 149 eyes (90%) and posterior capsule rupture in 27 eyes (16%). With the exception of one eye lost to follow-up, the results of these cases were satisfactory. A postoperative visual acuity of better than 20/20 was achieved in 45 eyes (58%), better than 20/40, in 70 eyes (91%). The main postoperative complications in 50 completely recorded eyes were anterior capsule opacity in 44 eyes (88%), severe iris atrophy because of intraoperative ultrasound in seven eyes (9%), and posterior capsule opacity causing visual disturbance in three eyes (4%).

Posterior capsule opacification: a specular microscopic study

Posterior capsule opacification following extracapsular cataract extraction is a manifestation of migration of lens epithelial cells onto the posterior capsule. Collagen production by these epithelial cells results in white "fibrotic" opacities. These cells have myoblastic features and their contraction produces wrinkling of the posterior capsule resulting in visual distortion. A high magnification, in vivo specular microscopic study of human posterior capsules following extracapsular cataract extraction is described. In vivo findings correlate with histopathologic observations made on opacified posterior capsules. Lens epithelial cells migrate onto the posterior capsule and produce basement membrane and collagen. Collagen production is associated with a spindle-shaped appearance of the hyperplastic cells. This technique is useful for clinical research on posterior capsule opacification, including the evaluation of interventions designed to treat or prevent this complication.

Posterior capsule opacification in pseudophakic eyes

Posterior capsule opacification following extracapsular cataract extraction is a manifestation of proliferation of anterior lens epithelium onto the posterior capsule. In addition to Elschnig pearl formation, vision is decreased in two ways. Multiple layers of proliferated epithelium produce a frank opacity. Also, the lens cells show myofibroblastic differentiation and their contraction produces numerous tiny wrinkles in the posterior capsule resulting in visual distortion. Because the cells that proliferate are anterior lens epithelial cells and because proliferation begins at the site of apposition of anterior capsular flap and the posterior capsule, a wide anterior capsulectomy should help reduce the risk of and delay the onset of visual loss from this complication of extracapsular surgery. Polishing the posterior capsule at the time of surgery will not help in this regard unless there is a complicated cataract with pre-existing posterior migration of lens epithelium. The presence of a potential cleavage plane between the proliferating epithelium and the posterior capsule provides a therapeutic alternative to surgical or laser discission.