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Background RPE65 is an essential molecule in the retinoid-visual cycle, and RPE65 gene mutations cause the congenital human blindness known as Leber congenital amaurosis (LCA). Somatic gene therapy delivered to [...]

The article presents a study that describes a presumed migration of Parelaphastrongylus tenuis through the spinal cord into the eye of a llama. It mentions that the blindness of the eye is attributed to the migration of the parasite through the central nervous tissue. It affirms that parasitic larvae can migrate within the retina through systemic circulation.

Corneal neovascularization (CNV) accompanies many corneal disorders, particularly inflammation and ulceration. However, granulation tissue formation is uncommon. Moreover, corneal epithelial healing defects frequently are complications of the diabetic state (diabetic keratopathy). Topical naltrexone (NTX) therapy facilitates corneal epithelial wound healing in a standardized model of corneal abrasions in diabetic rats. Recently, we have noticed an unusual form of keratopathy accompanied by vascularization and granulation tissue formation associated with delayed epithelial wound healing in diabetic rats. The purpose of the present study was to determine if this keratopathy could be prevented with topical NTX therapy. Type-1 diabetes (glucose levels >400 mg/dl) was induced with streptozotocin. Eight weeks after induction of diabetes, a 5 mm central corneal wound was created in the right eye of each rat. Eye drops (0.05 ml) of 10[sub -4] or 10[sub -5] M NTX, or sterile vehicle (SV), were given topically for 4 times daily over a 7 day period. Normal (non-diabetic) rats received SV. CNV was monitored with a hand held Zeiss Slit-Lamp (Zeiss HSO 10 Hand Slit Lamp, Dublin, CA) every other day for a 3-week period after initial wounding. Trichrome histological staining was performed to determine the presence and extent of CNV, and hematoxylin and eosin staining was utilized for investigation of inflammatory cells. CNV did not occur in normal SV rats (n=26), or DB rats receiving 10[sup -4] M or 10[sup -5] M NTX (n=l 8/treatment). CNV was present in 41% of DB SV rats (n=29). The incidence of CNV in DB SV animals was significantly different from the Normal SV group, as well as from DB rats receiving 10[sup -4] M or 10[sup -5] M NTX (p<0.001). Granulation tissue was not present in the corneas of the animals with CNV until 4 days after onset of the CNV. These data indicate that topically applied NTX prevents neovascularization and granulation tissue formation in our standard model of diabetic corneal abrasion. [ABSTRACT FROM AUTHOR]

CASE DESCRIPTION A client-owned 2-year-old 1.8-kg (4-lb) male pet Rouen duck (Anas platyrhynchos domesticus) was evaluated because of severe swelling around the left eye following traumatic injury to the upper and lower eyelids and 2 associated surgeries that resulted in the removal of the entire upper and lower eyelid margins. CLINICAL FINDINGS At initial evaluation, ankyloblepharon of the left eye was observed, with no upper or lower eyelid margins and a large, round, fluctuant subcutaneous mass over the left orbit. Orbital exploration and histologic examination revealed a benign cyst consisting of fibrous tissue, conjunctiva, and skeletal muscle bundles. Bacterial culture of cystic fluid yielded few Staphylococcus delphini. TREATMENT AND OUTCOME Excision of the cyst and evisceration of the left globe were performed, and once daily treatment with orally administered enrofloxacin suspension (12.6 mg/kg [5.7 mg/lb]) and meloxicam (I mg/kg [0.45 mg/lb]) was initiated. Over the next 4 days, the cyst redeveloped and progressively enlarged. Accumulated fluid was aspirated from the cyst, and 20 mg of gentamicin was injected intraorbitally with ultrasound guidance. Over the subsequent 27-month period, no recurrence of clinical signs or adverse effects were reported by the owner. CLINICAL RELEVANCE To the authors' knowledge, this is the first report of cyst formation after adnexal injury and evisceration in birds and its successful treatment with intralesional gentamicin injection. Findings emphasized the importance of preserving lacrimal puncta during adnexal or eye removal surgeries in birds. Intralesional injection of gentamicin with the goal of destroying fluid-producing cells may be a safe and effective way to treat intraorbital cysts in birds and other species, although additional research would be required to confirm this. [ABSTRACT FROM AUTHOR]

This report describes a unique case of presumed migration of Parelaphastrongylus tenuis through the spinal cord into the eye of a llama where it survived and matured within the ocular environment. Blindness of the eye was most likely attributable to migration of the parasite through the central nervous tissue.