Measurement of the Depth of the Anterior Chamber in Animals Using Scheimpflug Photography

Abstract

The technique of Scheimpflug photography was used to measure changes in depth of the anterior chamber of the eye and of lens thickness in small laboratory animals (Sprague-Dawley [SD] and Brown-Norway [BN] rats). The data were recorded with two different systems: the Topcon SL-45 camera, combined with linear microdensitometry, and the Zeiss SLC system. Values were recorded from normal unaffected eyes, in streptozotocin-induced diabetic animals, in those with naphthalene cataracts, and in those with cataracts induced by ultraviolet B (UVB) irradiation. In addition, the effect of topically applied beta-blockers (befunolol, betaxolol, timolol) on chamber depth was tested. The chamber depth increased constantly in normal eyes over the whole 6 week experimental period, accompanied by a constant increase in lens thickness. Under diabetic conditions, the depth increased minimally in BN rats and even slightly decreased in SD rats, in both cases accompanied by a massive lens swelling, as reflected by a prominent increase in lens thickness. In naphthalene cataracts, chamber depth decreased slightly during the second half of the experimental period, accompanied by a constant increase in lens thickness. Although different in their effects, beta-blockers in general clearly showed enhancing effects combined with diabetic cataracts: the anterior chamber became even narrower. In combination with the UVB cataract model, their effects were less pronounced.