Introduction

Glaucoma presents as a group of well recognized pathological changes involving the globe. These may result from one or more of a number of ocular disorders whose common end point is prolonged elevation of the intraocular pressure above normal limits. Corneal ulceration in cats is usually secondary to trauma. This report describes the successful clinical management of glaucoma and corneal ulceration in a cat.

History, Clinical Examination and Management

A two year old intact female cat was presented to the Teaching Veterinary Clinical Complex, Faculty of Veterinary sciences and Animal Husbandry Shuhama, SKUAST-K, with the history of reduced appetite, intermittent aggressive behavior and impaired vision from last 15days. As per owner there was gradual bulging of eye balls (over 15 days) and both eyes became red in color 6 days back. The owner had self medicated the cat with antibiotic and steroid eye drops and systemic antibiotics without any improvement, rather the cat became blind by left eye. The general clinical examination revealed normal temperature and mild increase in heart and respiration rates. The cat was active having dry and bulged eyes and hyphema in both eyes. The cat did not stumble on obstacle test. Maze test and pupillary light reflex were intact in right eye but absent in left eye. There was a corneal ulcer in right eye which was confirmed by fluoresce dye test (Fig. 1).

Fig. 1: Cat with bulged red eyes and fluoresce stained corneal ulcer in right eye (at day 0)

The intraocular pressure (IOP) measured with Schiotz tonometer was high in both eyes (40 mmHg in left and 46 mmHg in right eye). Ocular ultrasonography was done with 10 MHz transducer after ocular anesthesia. Ocular ultrasonography revealed cataract lens, retinal detachment and vitreous echogenic deposits in left eye (Fig. 2 and 3) but normal right eye.

Fig.2: Ocular ultrasonogram showing retinal detachment (a) and vitreous echogenic deposits (b)

Fig. 3: Ocular Ultrasonogram showing cataract lens (a)

On the basis of high IOP and clinical findings the cat was diagnosed to have glaucoma and corneal ulceration. The owner was advised to discontinue the self given medications especially the steroid eye drops. The cat was treated with eye drops (each ml of drops contained 22.26 mg of dorzolamide hydrochloride and 6.83 mg timolol maleate), ointment containing Nitrogen/Fresh Human Placental Extract – 0.25%/0.1g, and Caroboxy-methylcellulose (IP-0.5%) eye drops. The medications were used thrice daily for a week. After one week there was significant reduction in IOP (32 mmHg in left and 28 mmHg in right eye) and eye size but the ulcer had not healed completely (Fig. 4). The same treatment was continued for another week but used twice daily. As per telephonic conversation with the owner the cat regained full eye sight in right eye before the completion of treatment. But owner was advised to continue the eye drops for another two weeks and even more if the condition reoccurred.

Fig. 4: Improvement in hyphema and corneal ulcer at day 7 of treatment

Discussion

Glaucoma is a relatively uncommon clinical diagnosis in the cat, compared to the dog, although it is likely that many feline cases go unrecognized (McLellan and Miller 2011). Depending on the underlying pathogenesis, glaucoma may be unilateral in presentation or, less often, bilateral, and are most often seen in adult cats (Wilkie 1999). However, in present case glaucoma was bilateral. Disturbance to the optic nerve head, in terms both of its microcirculation and of the axoplasmic flow in its retinal ganglion cell axons, is the earliest and most significant effect of glaucoma. These changes are accompanied by retinal necrosis, which occurs as the result of a reduction in choroidal vascular perfusion, and this effect is greatest initially in the non-tapetal fundus (Nasisse 2006). In an uncontrolled situation, these events may progress to complete and irreversible blindness in the affected eye which was observed in left eye in present case.

Glaucoma is a medical emergency and IOP need to be decreased instantly by use of osmotic diuretics like manitol. In present case we did not use manitol because the cat was active and stable. The feline eye is remarkably resilient in terms of susceptibility to glaucomatous damage with relative preservation of ganglion cells in the retina of cats who have sustained acute IOP elevations, and relatively minor corneal changes observed (McLellan and Miller 2011). The present cat did not show typical signs of glaucoma except increased IOP and retinal detachment in left eye. We assume that glaucoma could have resulted in decrease in iridiocorneal angle leading to decreased tear production and hence corneal dryness. The dryness may have resulted in corneal ulceration, aggravated by use of steroid eye drops. The degree of discomfort, or at least overt clinical signs of discomfort, is highly variable in affected cats, and there are seldom signs of persistent, severe ocular discomfort unless IOP is markedly elevated (Morgan 1986).

In one retrospective study, 73% of glaucomatous cats were blind at the time of initial presentation (Blocker and van der Woerdt 2001). However, some vision may be preserved in chronically glaucomatous cats despite gross buphthalmos (Hampson et al., 2002) which could have been possible in the present case. The outlook for vision in cases of glaucoma is always guarded, and it remains one of the most challenging and potentially frustrating conditions for the clinician to manage (McLellan and Miller 2011). So, early recognition of the problem followed by prompt, appropriate therapy is essential if sight is to be preserved.

References

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