Evaluation of a soluble sustained-release ophthalmic delivery unit in the dog.

A 5-mg hydroxypropyl cellulose soluble ocular insert was evaluated by placement in the upper and the lower conjunctival and bulbar nictitating membrane fornices in normal dogs. The insert was easily placed in the conjunctival fornices, but was difficult to place in the bulbar nictitating membrane fornix. The conjunctival inserts did not produce irritation of the cornea and the conjunctiva. Placement of the inserts beneath the nictitating membrane produced local irritation and chemosis. The sites of highest to lowest retention for the insert were upper conjunctival fornix, bulbar nictitating membrane fornix, and lastly, lower conjunctival fornix. Dissolution was nearly complete in 8 hours.     

Morphologic alterations in the anterior lens capsule of canine eyes with cataracts

OBJECTIVE: To examine the morphologic changes in the anterior lens capsule and lens epithelium of canine eyes with cataracts. SAMPLE POPULATION: Anterior lens capsules from the eyes of 25 dogs with cataracts and from an additional 10 canine globes with lenses subjectively assessed to be normal. PROCEDURE: Thickness of each anterior lens capsule was measured by use of a digital microscopic camera and imaging software. All 25 capsules from eyes with cataracts were submitted for light microscopy; 4 were also submitted for electron microscopy. RESULTS: Thickness of the anterior lens capsule increased with age for the normal lenses and the lenses with cataracts; the change with age was similar for both groups. Light microscopy revealed fibrous metaplasia of lens epithelial cells in 7 of 25 anterior lens capsules with focal thickenings of the posterior aspect of the capsule. Electron microscopy revealed deposition of collagen and basement membrane-like material by fibroblast-like cells. CONCLUSIONS: Results indicate that thickness of the anterior lens capsule in dogs increases with age and that this increase in thickness is not significantly different between normal lenses and lenses with cataracts. In addition, epithelial cells from lenses with cataracts may undergo metaplasia to form plaques composed of fibrous tissue and ectopic basement membrane produced by epithelial cells.     

Implantation of a foldable intraocular lens in dogs

A 1-piece, tripod-shaped, acrylic intraocular lens was implanted in the posterior chamber after phacoemulsification to remove cataracts in 20 eyes of 16 dogs. Biomicroscopy and intraocular pressure measurements were performed at 1, 8, 30, and 90 days after surgery; retinoscopy was performed at day 30. Complications were not encountered during implantation of the lens. All dogs had mild ocular inflammation characterized predominantly by aqueous flare and mild corneal edema at day 1, which resolved completely by day 8; 3 eyes had mild hyphema at day 1, which resolved by day 8. Three eyes developed fibrin in the anterior chamber, which resolved by day 30. Two eyes developed distorted pupils caused by adherence of vitreous humor or fibrin to the incision site. Postoperative intraocular pressure ranged from 7 to 21 mm Hg. Implantation resulted in 9 emmotropic eyes, 5 myopic eyes, and 6 hyperopic eyes. Maintenance of central lens position was excellent in 19 eyes; in 1 eyes, a disclocated superior haptic at day 2 was easily repositioned.     

Disturbances in European beech water relation during an extreme drought

Context

In the context of a probable increase in intensity and frequency of extreme summer drought events, a better understanding of the key processes involved in water relations is needed to improve the theoretical foundations of predictive process-based models.

Aims

This paper aims to analyse how temperate deciduous trees cope with water shortage.

Methods

The exceptional summer drought of 2003 in Europe provided an opportunity to monitor stomatal conductance and twig water potential in European beech (Fagus sylvatica L.) at predawn and midday and to analyse variations with respect to leaf height within the canopy. By comparing our field measurements of twig water potential to values found in the literature, we confirmed the strong impact of soil water shortage on crown water relations.

Results

This paper shows that (1) the vertical gradient of stomatal conductance within the crown disappeared under extreme soil water depletion; (2) at maximum drought intensity, predawn twig water potential (ψ _pd) reached ?2.3 MPa at a height of 14 m in the crown and ?2.0 MPa at a height of 10 m. The significant differences in ψ _pd between the two measurement heights in the canopy may be due to night transpiration; (3) there was a close relationship between predawn twig water potential and relative extractable soil water; (4) as drought conditions intensified, there was a close relationship between canopy radiation interception and predawn water potential, as estimated daily from relative extractable soil water.