Cataract surgeries were carried out in fifty-one eyes of 36 horses over a 15-year period. Cataracts were removed using phacofragmentation and aspiration. Useful vision was restored after surgery in 30 horses. One year after surgery 16 of the 19 horses for which follow up information was available were still visual with several still being used as working horses. At 5-6 years after surgery three horses were still visual. The most frequent intraoperative complication was tearing of the posterior lens capsule. The most frequent postoperative problem was superficial corneal ulceration. Four eyes in three horses developed postoperative infectious endophthalmitis resulting in blindness.

Abstract. Ocular contents from a horse with a 4-week history of severe unilateral uveitis were submitted for histopathologic examination. A severe unilateral granulomatous chorioretinitis with intralesional Halicephalobus deletrix was diagnosed. The horse developed progressive neurologic signs several days following the surgery to remove ocular contents and implant a prosthesis and was subsequently euthanatized. A severe multifocal granulomatous encephalitis with intralesional H. deletrix, localized primarily to the optic chiasm, thalamus, and brain stem, was diagnosed from tissues acquired at necropsy. The other eye was not affected. This is the first report of ocular parasitism by H. deletrix and suggests possible systemic dissemination from a primary site in the eye.

The lens capsule of the eye functions, in part, as a deformable support through which the ciliary body applies tractions that can alter lens curvature and corresponding refractive power during the process of accommodation. Although it has long been recognized that characterization of the mechanical properties of the lens capsule is fundamental to understanding this physiologic process as well as clinical interventions, prior data have been limited by one-dimensional testing of excised specimens despite the existence of multiaxial loading in vivo. In this paper, we employ a novel experimental approach to study in situ the regional, multiaxial mechanical behavior of both normal and diabetic human anterior lens capsules. Furthermore, we use these data to calculate material parameters in a nonlinear stress-strain relation via a custom sub-domain inverse finite element method (FEM). These parameters are then used to predict capsular stresses in response to imposed loads using a forward FEM model. Our results for both normal and diabetic human eyes show that the anterior lens capsule exhibits a nonlinear pseudoelastic behavior over finite strains that is typical of soft tissues, and that strains are principal relative to meridional and circumferential directions. Experimental data and parameter estimation suggest further that the capsule is regionally anisotropic, with the circumferential direction becoming increasingly stiffer than the meridional direction towards the equator. Although both normal and diabetic lens capsules exhibited these general characteristic behaviors, diabetic capsules were significantly stiffer at each distension. Finally, the forward FEM model predicted a nearly uniform, equibiaxial stress field during normalcy that will be perturbed by cataract surgery. Such mechanical perturbations may be an underlying modulator of the sustained errant epithelial cell behavior that is observed well after cataract surgery and may ultimately contribute to opacification of the posterior lens capsule.

The objective of this study was to determine the frequency of intraoperative contamination of the anterior chamber with viable microorganisms during cataract phacoemulsification and intraocular lens implantation, and to evaluate the relationship of contaminant microorganisms to patients' extraocular and nasal cavity floras. Also, the impact of various aspects of the patient history and phacoemulsification procedure on the incidence of positive postoperative anterior chamber cultures was investigated. Twenty-two eyes from 13 dogs presented for elective cataract phacoemulsification and intraocular lens implantation were studied. Preoperatively, microbiologic samples of the conjunctiva, eyelid margins, nares, and rostral nasal cavity were collected. Postoperatively, anterior chamber fluid was aspirated. Samples were submitted for aerobic/anaerobic bacteriologic culture and antimicrobial susceptibility, Mycoplasma culture, and fungal culture. Anterior chamber aspirates collected at the conclusion of surgery were culture positive for at least one organism in 22.7% of eyes. Three aerobic bacteria and three fungi were isolated from the anterior chamber aspirates. Two fungi and one bacterium isolated from the anterior chamber were typed identically, and the bacterium had a similar antibiogram to organisms recovered from the patient's conjunctiva and eyelid margin. No statistically significant difference in contamination frequency was found for the investigated patient and surgical variables. We conclude that intraoperative contamination of the anterior chamber with viable bacterial and fungal organisms is a common occurrence in canine patients undergoing cataract phacoemulsification and intraocular lens implantation, and the external ocular flora is a likely source of some of these contaminating microorganisms. This contamination is independent of the patient and surgical variables investigated.

The biomechanics of the lens capsule of the eye is important both in physiologic processes such as accommodation and clinical treatments such as cataract surgery. Although the lens capsule experiences multiaxial stresses in vivo, there have been no measurements of its multiaxial properties or possible regional heterogeneities. Rather all prior mechanical data have come from 1-D pressure-volume or uniaxial force-length tests. Here, we report a new experimental approach to study in situ the regional, multiaxial mechanical behavior of the lens capsule. Moreover, we report multiaxial data suggesting that the porcine anterior lens capsule exhibits a typical nonlinear pseudo-elastic behavior over finite strains, that the in situ state is pre-stressed multi-axially, and that the meridional and circumferential directions are principal directions of strain, which is nearly equi-biaxial at the pole but less so towards the equator. Such data are fundamental to much needed constitutive formulations.

The effect of the topical carbonic anhydrase inhibitor, dorzolamide, on intraocular pressure in cats was studied. The intraocular pressure of both eyes of eight healthy cats was measured using applanation tonometery (Tono-Pen) during two phases: control and treatment. Both eyes were treated with 2% dorzolamide twice a day during the treatment phase. Application of dorzolamide resulted in a significant decrease of intraocular pressure over the treatment phase. By the fourth and fifth day of treatment, the mean intraocular pressure (+/- standard deviation) was 9.7 (+/- 1.5) mmHg, whereas the mean (+/- standard deviation) for the last 2 days of the control period was 12.2 (+/- 2.0) mmHg. Based on this study, dorzolamide is a potentially effective treatment for glaucoma in cats, significantly lowering intraocular pressure.

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Two‐dimensional real‐time ultrasonography was performed with three different methods to determine the optimal technique for scanning canine orbital soft tissues. The three techniques included positioning the transducer on the clipped closed eyelid (eyelid contact method), directly on the cornea (corneal contact method), or on a small waterfilled balloon in direct contact with the cornea (water bath offset method). Horizontal and vertical images from the three techniques were compared and graded for diagnostic quality. The corneal contact method provided superior anatomic definition of the posterior globe and extraorbital tissues, whereas the water bath method gave higher‐quality images of the anterior chamber and lens. Use of the eyelid contact method to image the eye and periorbital structures was not recommended because of multiple artifacts that severely degrade the image.