Rabbit conjunctival epithelium exhibits UTP-dependent Cl(-) secretion into the tears. We investigated whether fluid secretion also takes place. Short-circuit current (I(sc)) was 14.9 +/- 1.4 microA/cm(2) (n = 16). Four P2Y(2) purinergic receptor agonists [UTP and the novel compounds INS365, INS306, and INS440 (Inspire Pharmaceuticals)] added apically (10 microM) resulted in temporary (approximately 30 min) I(sc) increases (88%, 66%, 57%, and 28%, respectively; n = 4 each). Importantly, the conjunctiva transported fluid from serosa to mucosa at a rate of 6.5 +/- 0.7 microl x h(-1) x cm(-2) (range 2.1--15.3, n = 20). Fluid transport was stimulated by mucosal additions of 10 microM: 1) UTP, from 7.4 +/- 2.3 to 10.7 +/- 3.3 microl x h(-1) x cm(-2), n = 5; and 2) INS365, from 6.3 +/- 1.0 to 9.8 +/- 2.5 microl. h(-1) x cm(-2), n = 5. Fluid transport was abolished by 1 mM ouabain (n = 5) and was drastically inhibited by 300 microM quinidine (from 6.4 +/- 1.2 to 3.6 +/- 1.0 microl x h(-1) x cm(-2), n = 4). We conclude that this epithelium secretes fluid actively and that P2Y(2) agonists stimulate both Cl(-) and fluid secretions.

A method for measuring the tilt and decentration of intraocular lenses (IOLs) in the static eye using the Purkinje image locations is presented. The patient fixates on a target that is coaxial with the camera or is at a predetermined angle with the camera axis. A telecentric stop is introduced in the camera so the positions of the Purkinje images on the film are independent of their distance from the camera. Measurements of the image locations on the film are used with anterior chamber depth and corneal curvature measurement to calculate the tilt and decentration of the IOL. In a group of 14 randomly selected patients with posterior chamber IOLs, 13 gave Purkinje images that could be measured. The average tilt was 7.8 degrees and the average decentration was 0.7 mm.

We report for the first time that cultured lens epithelial cell layers and rabbit lenses in vitro transport fluid. Layers of the αTN4 mouse cell line and bovine cell cultures were grown to confluence on permeable membrane inserts. Fluid movement across cultured layers and excised rabbit lenses was determined by volume clamp (37°C). Cultured layers transported fluid from their basal to their apical sides against a pressure head of 3 cmH2O. Rates were (in μl ⋅ h−1 ⋅ cm−2) 3.3 ± 0.3 for αTN4 cells ( n = 27) and 4.7 ± 1.0 for bovine layers ( n = 6). Quinidine, a blocker of K+ channels, and p-chloromercuribenzenesulfonate and HgCl2, inhibitors of aquaporins, inhibited fluid transport. Rabbit lenses transported fluid from their anterior to their posterior sides against a 2.5-cmH2O pressure head at 10.3 ± 0.62 μl ⋅ h−1 ⋅ lens−1( n = 5) and along the same pressure head at 12.5 ± 1.1 μl ⋅ h−1 ⋅ lens−1( n = 6). We calculate that this flow could wash the lens extracellular space by convection about once every 2 h and therefore might contribute to lens homeostasis and transparency.

A doublet contact element was added to a long-working-distance objective to increase the numerical aperture to 0.75 and to maintain the focus during in vivo examination of the eye. Optical sectioning by use of confocal slits permits visualization of weakly scattering structures within the cornea. With photographic film and a 1/60-s exposure time to limit the effect of eye movement, an effective optical section half-thickness of approximately 20 microns was realized. Structures observed in the cornea include epithelial cells (surface, wing, and basal cells), nerve-fiber bundles in the subepithelial region, keratocytes and inflammatory cells in the stroma, and endothelial cells.