Intraocular Structure Research Articles

Micrometer-Scale Resolution Imaging of the Anterior Eye In Vivo With Optical Coherence Tomography

To demonstrate a new diagnostic technique, optical coherence tomography, for high-resolution cross-sectional imaging of structures in the anterior segment of the human eye in vivo. Optical coherence tomography is a new, noninvasive, noncontact optical imaging modality that has spatial resolution superior to that of conventional clinical ultrasonography (< 20 microns) and high sensitivity (dynamic range, > 90 dB). Survey of intraocular structure and dimension measurements. Laboratory. Convenience sample. Correlation with range of accepted normal intraocular structure profiles and dimensions. Direct in vivo measurements with micrometer-scale resolution were performed of corneal thickness and surface profile (including visualization of the corneal epithelium), anterior chamber depth and angle, and iris thickness and surface profile. Dense nuclear cataracts were successfully imaged through their full thickness in a cold cataract model in calf eyes in vitro. Optical coherence tomography has potential as a diagnostic tool for applications in noncontact biometry, anterior chamber angle assessment, identification and monitoring of intraocular masses and tumors, and elucidation of abnormalities of the cornea, iris, and crystalline lens.

The Dimensions of Eyes with Chronic Angle-closure Glaucoma

The measurement of eyes with primary angle-closure glaucoma has been comprehensively documented in people of European ethnic origin. In comparison, few biometric studies have examined the relationship of one intraocular structure to another in people of Oriental or African ethnic background with primary angle-closure glaucoma. To determine the ocular characteristics of people with this ethnic background suffering from chronic angleclosure glacoma, both eyes of 46 patients with chronic angle-closure glaucoma were measured by contact A-scan ultrasonography, and the measurements were compared with those found in two groups of 23 matched normals. The correlation between the measurements obtained in the right and left eyes in each group was statistically significant (p < 0.001). Although the mean axial length was less (22.43 mm vs. 23.17 and 23.25 mm, p = 0.0001), the mean anterior chamber depth shallower (2.48 mm vs. 2.80 and 2.81 mm, p < 0.001). and the mean "relative lens position'' more anterior in eyes with chronic angle-closure glaucoma compared with normal, the mean lens thickness in all three groups was similar (4.73 mm). These measurements are significantly different from those reported in other ethnic groups. In comparison with the previously reported findings in Europeans, an anterior lens position without significant lens enlargement is responsible for the crowded anterior segment in our patients with chronic angle-closure glaucoma.

A New Ophthalmic Electronic Videoendoscope System for Intraocular Surgery

A new ophthalmic electronic videoendoscope system has a 20-guage probe for intraocular observation, a standard size for vitreous microsurgical instruments, and both endoscopic and operating microscopic images are displayed on a split-screen monitor system to provide surgeos a simultaneous view of both images. Using this endoscope system at any time during surgery, surgeons can examine the intraocular structure such as the ciliary sulcus, pars plana, or vitreous base and obtain valuable but otherwise unobtainable information for completing the surgery.

Characterization of galactose-containing glycoconjugates in the human retina: A lectin histochemical study

Seven specimens of morphologically normal formalin-fixed and paraffin-embedded human retina were studied using a panel of fourteen biotinylated lectins, all of which react with glycoconjugates containing galactose and N-acetylgalactosamine residues. Agaricus bisporus (ABA), Bauhinia purpurea (BPA), Phaseolus vulgaris (PHA-E), peanut (PNA) and Ricinus communis (RCA-I) agglutinins labeled photoreceptor cells prior to enzymatic predigestion. BPA and PNA bound specifically to cones. The plexiform layers reacted with ABA, BPA and PHA-E, while only ABA and PHA-E labeled the nuclear layers. After pretreatment with neuraminidase to remove terminal sialic acid, all five lectins, as well as Erythrina cristagalli (ECA), Helix pomatia (HPA) and Maclura pomifera (MPA) agglutinins labeled both rods and cones. Furthermore, the plexiform layers additionally reacted with ECA, PNA and RCA-I, and the nuclear layers with BPA and RCA-I after neuraminidase pretreatment. Retinal vascular endothelial cells consistently bound ABA, ECA, PHA-E and RCA-I, but they could also bind BPA, HPA, Bandeiraea simplicifolia (BSA-I), Dolichos biflorus (DBA) and Euonymus europaeus (EEA) agglutinins in unpretreated sections, as well as MPA, PNA, soybean (SBA) and Sophora japonica (SJA) agglutinins subsequent to predigestion with neuraminidase. The nonpigmented ciliary epithelium reacted with the same lectins as photoreceptor cells, but it was also labeled by DBA. Sambucus nigra agglutinin (SNA) did not specifically bind to any intraocular structure. These findings favor the theory that, in unpretreated specimens, Gal(beta 1----3)GalNAc (BPA and PNA) is mainly responsible for labeling of cones, while Gal(beta 1----3/4)GlcNAc units, partly substituted with terminal sialic acid (PHA-E and RCA-I), explain labeling of rods. Following pretreatment with neuraminidase, further Gal(beta 1----3)GalNAc (BPA and PNA) and, especially, Gal(beta 1----3/4)GlcNAc (BPA, ECA, PHA-E, PNA and RCA-I) and alpha GalNAc units (BPA, HPA and MPA), the latter partly linked to the protein backbone, contribute to labeling of photoreceptor cells. Gal(beta 1----3/4)GlcNAc units may be mainly responsible for labeling of nuclear and plexiform layers. Finally, other related receptor sites (SBA and SJA), some of which are blood-group specific (BSA-I, DBA, EEA and HPA) are restricted to retinal vascular endothelia.

In vivo binding of topically applied human bFGF on rabbit corneal epithelial wound.

We present the results of the first evaluation of human placenta extracted basic fibroblast growth factor (bFGF) in a rabbit corneal epithelium wound-healing model. Healing dose-response experiments after selective epithelial wounding with iodine vapors demonstrated that bFGF accelerated the repair process in a saturable manner. Corneal binding of topically applied 125I-labeled bFGF was investigated using radioassay and autoradiographic techniques. Basic FGF was shown to bind specifically to denuded epithelial basement membrane in a very stable fashion and not to the intact epithelium. No transfer of the topical bFGF to the aqueous humor or any intraocular structure could be observed. The stability of this interaction was further demonstrated by reextracting and characterizing the labeled factor from treated corneas. The specificity of the fixation was documented by in vivo topical competition with unlabeled bFGF or heparin. We propose that bFGF-basement membrane interactions play a role in corneal wound healing.

THE USE OF A MOHAIR BRUSH IN INTRAOCULAR SURGERY

To the Editor: —Barraquer and Boberg-Ans recently described a technique ( Brit. J. Ophth. 43:69-77 [Feb.] 1959) whereby injury to the lens may be prevented during intraocular procedures. These authors use a small mohair brush in their intraocular surgery. Even if the lens is accidently touched they find that no damage is produced by the soft brush either to the lens or any other intraocular structure. In addition, they describe the brush as being a very versatile piece of equipment and in most instances it can satisfactorily do the work of an irrigator, forceps, or iris repositer. After reading their description, I began using a small mohair brush for intraocular procedures and have found it to be most satisfactory. The brush is readily available at any store selling artist supplies. It is sterilized by boiling for 15 minutes before being used and this does not change the soft texture of the