Richard J. McMullen

Long-term outcome after implantation of a suprachoroidal cyclosporine drug delivery device in horses with recurrent uveitis.

OBJECTIVE To determine the long-term efficacy, complications, and duration of effect of a cyclosporine (CsA) suprachoroidal implant (CSI) in horses with equine recurrent uveitis (ERU). METHODS Horses with ERU were treated with a 6-mm diameter, 25 mg, reservoir matrix CsA implant in the deep sclera adjacent to the suprachoroidal space. Horses with follow-up >1 year were examined for frequency of uveitis episodes, complications, and vision at last recheck. RESULTS Data from 151 eyes of 133 horses from the USA and Europe that had CsA devices implanted for ERU were reviewed. Follow-up time ranged from 13 to 85 months after surgery, with a mean and median follow-up time of 28.9 and 26.3 months, respectively. Overall, at last follow-up 78.8% of eyes were considered visual and the overall mean frequency of uveitis episodes after CSI was 0.09 ± SD 0.08 episodes per month. The most common complications leading to vision loss at last follow-up were persistent uveitis episodes (54%), glaucoma (22%), mature cataracts (16%), and retinal detachment (6%). Persistent uveitis episodes tended to be the highest cause of vision loss in horses with <24 months and >48 months of follow-up. CONCLUSIONS This study demonstrated the long-term maintenance of vision of horses with ERU implanted with a CSI. The increased vision loss related to uveitis episode of inflammation in eyes after the likely depletion of CsA from the CSI suggests that a repeat CSI may be required at or before 48 months after surgery.

Evaluation of 30- and 25-diopter intraocular lens implants in equine eyes after surgical extraction of the lens

OBJECTIVE To determine appropriate intraocular lens (IOL) implant strength to approximate emmetropia in horses. SAMPLE POPULATION 16 enucleated globes and 4 adult horses. PROCEDURES Lens diameter of 10 enucleated globes was measured. Results were used to determine the appropriate-sized IOL implant for insertion in 6 enucleated globes and 4 eyes of adult horses. Streak retinoscopy and ocular ultrasonography were performed before and after insertion of 30-diopter (D) IOL implants (enucleated globes) and insertion of 25-D IOL implants (adult horses). RESULTS In enucleated globes, mean +/- SD lens diameter was 20.14 +/- 0.75 mm. Preoperative and postoperative refractive state of enucleated globes with 30-D IOL implants was -0.46 +/- 1.03 D and -2.47 +/- 1.03 D, respectively; preoperative and postoperative difference in refraction was 2.96 +/- 0.84 D. Preoperative anterior chamber (AC) depth, crystalline lens thickness (CLT), and axial globe length (AxL) were 712 +/- 0.82 mm, 11.32 +/- 0.81 mm, and 40.52 +/- 1.26 mm, respectively; postoperative AC depth was 10.76 +/- 1.16 mm. Mean ratio of preoperative to postoperative AC depth was 0.68. In eyes receiving 25-D IOL implants, preoperative and postoperative mean refractive error was 0.08 +/- 0.68 D and -3.94 +/- 1.88 D, respectively. Preoperative AC depth, CLT, and AxL were 6.36 +/- 0.22 mm, 10.92 +/- 1.92 mm, and 38.64 +/- 2.59 mm, respectively. Postoperative AC depth was 8.99 +/- 1.68 mm. Mean ratio of preoperative to postoperative AC depth was 0.73. CONCLUSIONS AND CLINICAL RELEVANCE Insertion of 30-D (enucleated globes) and 25-D IOL implants (adult horses) resulted in overcorrection of refractive error.

Epibulbar melanoma in a foal.

A case of epibulbar melanoma in a 6-month-old, gelded, chestnut Hanoverian foal is reported. The location and clinical appearance upon initial presentation led to the tentative diagnosis of staphyloma or a congenital mass of unknown origin. An attempt was made to surgically excise the mass under general anesthesia, but due to its infiltrative nature and intraoperative appearance, most, but not all was removed without compromising the integrity of the globe. Histopathological evaluation revealed a multinodular to packeted, poorly demarcated, unencapsulated, infiltrative exophytic melanocytic neoplasm composed of bundles and nests of plump spindloid to polygonal heavily pigmented epithelioid neoplastic cells interspersed with pigment-laden macrophages within a fine fibrovascular stroma. Upon examination after enucleation, neoplastic cells were found to infiltrate into the lateral cornea, sclera and the choroid. This is a unique case of an epibulbar melanoma with choroidal invasion in a foal. Based on the sudden onset and rapid growth as well as the histological evidence of invasion, well-differentiated features, heavy pigmentation, and no apparent mitoses, this neoplasm was considered to be a low-grade malignant melanoma. At 14 months after excision there is no evidence of recurrence.

A retrospective comparison of surgical removal and subsequent CO2 laser ablation versus topical administration of mitomycin C as therapy for equine corneolimbal squamous cell carcinoma

OBJECTIVE   To compare the complications and nonrecurrence rate following topical mitomycin C (MMC) therapy vs. CO(2) laser ablation for treating equine corneolimbal squamous cell carcinoma (SCC). STUDY DESIGN   Retrospective study. SAMPLE POPULATION   Twenty-five horses with corneolimbal SCC. PROCEDURES   Medical records of horses undergoing surgical tumor resection followed by either topical MMC therapy (0.04%) or CO(2) laser ablation between the years of 2004 and 2010 were reviewed. Recurrence and complications were compared between groups and within MMC subgroups defined by the time at which treatment was initiated relative to surgery. RESULTS   Therapy with topical MMC resulted in a nonrecurrence rate comparable to that achieved with CO(2) laser ablation (82.4% vs. 85.7%, respectively). Initiation of MMC following epithelialization of the surgical site a mean of 15 days postoperatively did not result in increased recurrence rates relative to treatment in the immediate postoperative period. Vision- or globe-threatening complications tended to occur with greater frequency in horses receiving topical MMC in the immediate postoperative period (5 of 6 major complications) relative to following epithelialization of the surgical site (1 of 6 major complications). CONCLUSIONS   Horses receiving adjunctive topical MMC therapy were no more likely to experience tumor recurrence than were horses undergoing CO(2) laser ablation in the horses in this study. Initiation of two to three rounds of MMC following epithelialization of the surgical site results in fewer major complications and achieves comparable disease resolution relative to treatment in the immediate postoperative period.

Effect of three treatment protocols on acute ocular hypertension after phacoemulsification and aspiration of cataracts in dogs.

OBJECTIVE To compare the effect of topical latanoprost, intracameral carbachol, or no adjunctive medical therapy on the development of acute postoperative hypertension (POH) and inflammation after routine phacoemulsification and aspiration (PA) of cataracts in dogs. DESIGN Retrospective study. PROCEDURES Dogs received either one drop of topical 0.005% latanoprost (21 dogs, 39 eyes), an intracameral injection of 0.3 mL of 0.01% carbachol (15 dogs, 30 eyes), or no adjunctive therapy (46 dogs, 90 eyes) immediately following PA of cataract(s). Intraocular pressure (IOP) was measured in all dogs 2 and 4 h after surgery. IOP was measured and aqueous flare assessed at 8 am the day after surgery. RESULTS Carbachol-treated dogs had significantly higher mean IOP (33.2 +/- SD 20.8 mmHg) 2 h after surgery than dogs receiving no adjunctive therapy (22.0 +/- SD 14.1 mmHg) (P = 0.049). There were no significant differences in IOP among groups at any other time point. There were no significant differences in number of POH episodes between dogs treated with carbachol (47%), latanoprost (29%), or dogs that received no adjunctive therapy (33%). There were no significant differences in mean aqueous flare grade between eyes treated with latanoprost (1.7 +/- SD 0.4) or carbachol (1.4 +/- SD 0.6), and eyes that received no adjunctive therapy (1.7 +/- SD 0.4). CONCLUSIONS Topical 0.005% latanoprost or intracameral injection of 0.3 mL of 0.01% carbachol after PA in dogs did not reduce POH or increase intraocular inflammation compared to dogs not receiving adjunctive therapy after PA of cataracts.

Infrared digital imaging of the equine anterior segment

Ocular photographs are an increasingly important method of documenting lesions for inclusion in medical records, teaching purposes, and research. Availability of affordable high-quality digital imaging equipment has allowed for enhanced capture of desired images because of immediate on-camera viewing and editing. Conversion of the standard digital camera sensor to one that is sensitive to infrared light (i.e. > 760 nm < 1 mm wavelength) can be done inexpensively. In the equine eye, advantages of infrared digital photography include increased contrast of anterior segment images, identification and monitoring of pigmentary changes, and increased visualization of the anterior segment through a cloudy or edematous cornea.

Retrospective evaluation of phacoemulsification and aspiration in 41 horses (46 eyes): visual outcomes vs. age, intraocular lens, and uveitis status.

OBJECTIVE To determine the effect of age at the time of surgery, intraocular lens (IOL) placement, and presence of chronic uveitis on visual outcome after phacoemulsification and aspiration (PA) of cataracts in horses. ANIMALS STUDIED Records of 41 horses (46 eyes) receiving unilateral or bilateral PA. METHODS Retrospective analysis of horses receiving unilateral or bilateral PA at the NCSU-VTH (35 horses, 39 eyes) and in Northern Italy (six horses, seven eyes) was performed. Visual status at last follow-up was compared to age at the time of surgery, IOL status, and presence of chronic uveitis preoperatively. Seven horses with chronic uveitis also underwent placement of a suprachoroidal cyclosporine implant. Clinical ophthalmic examinations and owner questionnaires were used to evaluate visual status. RESULTS Twenty-one of 46 eyes (46%) received an IOL and 12 of 46 eyes (26%) had chronic uveitis. Overall, 25 of 46 eyes (54%) were visual at last follow-up (mean 35.1 ± 34.8 months). Age (mean 8.6 ± 7.7 years) was not significantly associated with visual outcome. Fourteen of 21 (67%) pseudophakic eyes and 11 of 25 (44%) aphakic eyes were visual at last follow-up (P = 0.342). Eyes with preoperative chronic uveitis were significantly less likely to be visual (3 of 12 eyes [25%]) than horses without preoperative chronic uveitis (22 of 34 eyes [65%]) (P = 0.023). CONCLUSIONS Horses with chronic uveitis had significantly less favorable visual outcome after PA. Older age at surgery and IOL use were not associated with poor visual outcome.

Phacoemulsification and +14 diopter intraocular lens placement in a Saddlebred foal

A 2-month-old, 110-kg Saddlebred filly presented for evaluation of bilateral cataracts. A hypermature cataract in the left eye (OS) and an incipient nuclear cataract in the right eye (OD) were diagnosed. Electroretinography and ocular ultrasound revealed no contraindications for surgical removal of the cataractous lens OS. Phacoemulsification and implantation of a +14 diopter (D) intraocular lens (IOL) OS were performed at 4 months of age without complication, with the exception of a partial iridectomy performed on a small iris section that prolapsed through the corneal incision. Complete ophthalmic examinations, including ocular ultrasound and streak retinoscopy, were performed 1, 2, 6 weeks, 4 months, 1, and 2 years postoperatively. Diffuse corneal edema and a superficial corneal ulcer developed OS during the early postoperative period and resolved without complication. Dyscoria was identified owing to anterior synechia of the dorsomedial iris at the incision site. Two years after surgery, menace response, palpebral reflex, dazzle reflex, and pupillary light reflexes were present in both eyes (OU). The IOL remained centrally positioned within the capsule, with mild anterior tilting of the superior portion of the IOL and mild fibrosis of the lens capsule. The postoperative net refractive error was +0.31 D OS. Based on this report, a +14 D IOL may be the appropriate choice following lens extraction in a foal to achieve refraction near emmetropia at maturity. To our knowledge, this is the first report of phacoemulsification and IOL implantation in a foal with long-term follow-up.

The effect of 1% tropicamide-induced mydriasis and cycloplegia on spherical refraction of the adult horse.

OBJECTIVES To determine the effects of tropicamide 1% on the refractive state of the adult equine globe and identify the most appropriate time period (in relation to mydriasis) to perform streak retinoscopy. ANIMALS STUDIED Eight university-owned mares of various ages and breeds. PROCEDURES Topical tropicamide 1% was applied to one randomly selected eye from each of the horses to induce mydriasis and cycloplegia. The contralateral eyes served as controls. Streak retinoscopy and pupillometry were performed prior to, and every 5 min after tropicamide 1% installation for 90 min. RESULTS All values are expressed as mean ± SD. Both horizontal (2.8 ± 0.74 mm) and vertical (7.3 ± 1.29 mm) mean pupil diameters increased significantly (P < 0.04) in the treatment eyes compared with the control eyes (horizontal [0.48 ± 0.85 mm] and vertical [1.06 ± 1.31 mm] pupil diameter). No significant differences in the refractive states of the treatment (horizontal: +0.25 ± 0.43 D and vertical: +0.41 ± 0.37 D) or control (horizontal: +0.34 ± 0.39 D and vertical: +0.41 ± 0.37 D) eyes were identified at any time point. Three of the eight treatment eyes demonstrated blurry or reversing streak reflexes during streak retinoscopy evaluation following the application of topical tropicamide 1%. CONCLUSIONS While these reflexes did not significantly influence streak retinoscopy results, their presence may subjectively influence a novice retinoscopists ability to obtain accurate results. Therefore, optimal streak retinoscopy results may be obtained prior to, or 40- to 45-min following the application of topical tropicamide 1%, once near-maximal dilation has been achieved.

Clinical, histopathological and immunohistochemical characterization of a novel equine ocular disorder: heterochromic iridocyclitis with secondary keratitis in adult horses.

OBJECTIVE To describe the clinical, histopathologic and immunohistochemical characteristics of an equine ocular inflammatory disease resulting in anterior uveitis and corneal endothelial inflammation associated with iris pigment dispersion and retrocorneal fibrous membrane (RFM) formation. DESIGN Retrospective study. ANIMALS STUDIED Sixteen horses with evidence of pigmented keratic precipitates (KPs), corneal edema, and/or iris depigmentation. Information collected from the medical records included signalment, clinical signs, prereferral treatment duration and response to therapy, ophthalmic examination findings, postreferral treatment, response to therapy, and outcome. RESULTS Twenty-one eyes from 16 horses were affected. Age ranged between 9 and 25 years (Average 16.1 years). Blepharospasm, epiphora, and/or corneal opacification were the first clinical signs noted. At the time of referral pigmented KPs, corneal edema, iridal depigmentation, and retrocorneal membranes were commonly seen. Treatment included topical and/or systemic anti-inflammatories and antibiotics with variable response. Reduction or cessation of anti-inflammatory therapy resulted in worsening of clinical signs and disease progression. Eight eyes ultimately required enucleation. Histopathology changes include iridal pigment loss and dispersion, RFM formation, and keratitis. Variable degrees of lymphoplasmacytic inflammation were dominated by T-cells within the corneal stroma, RFM, iris, and ciliary body with occasional multinucleated giant cells. CONCLUSIONS Heterochromic iridocyclitis with secondary keratitis (HIK) is characterized by uveal inflammation with pigment dispersion and suspected corneal endothelial dysfunction. Horses being treated for HIK require diligent and frequent follow-up examinations in combination with aggressive local immune suppression to control the disease. However, HIK may not respond to therapy and enucleation may ultimately be required to ensure the horses comfort.