INTRAOCULAR PRESSURE IN SOUTHERN ROCKHOPPER (EUDYPTES CHRYSOCOME) AND MACARONI PENGUINS (EUDYPTES CHRYSOLOPHUS): EVALUATION OF INFLUENCING FACTORS

Abstract

Ophthalmic examinations were performed on 160 macaroni penguins (Eudyptes chrysolophus) and 90 southern rockhopper penguins (Eudyptes chrysocome) at eight North American zoos and aquaria. Intraocular pressure (IOP) was measured using rebound tonometry while penguins were held in two different body positions. Correlations between IOP and factors including age, body position, eye pathology, and housing parameters were evaluated. Normal macaroni penguins had a mean IOP of 42.0 ± 9.7 mm Hg. Normal rockhopper penguins had a mean IOP of 32.9 ± 6.2 mm Hg. Neither species had significantly different IOP between sexes or between left and right eyes of the same penguin. In both species, there was a negative linear correlation between age and IOP. In the macaroni population, IOP was significantly higher when IOP measurement was performed before ophthalmic exam; this was not true in rockhoppers. In both species, IOP measured in a horizontal body position was significantly higher than IOP measured in a vertical body position. In both species, eyes with corneal lesions had significantly lower IOP than normal eyes. In the macaroni penguin, eyes with rubeosis iridis had significantly lower IOP than normal eyes. In macaroni penguins, eyes with cataracts had significantly lower mean IOP than normal eyes; this was not true for rockhoppers.

Characterisation of cataracts and other ophthalmic findings in various species of captive penguins

“…6,12 Consistent with previous reports, no overt signs of active disease, such as blepharospasm, discharge or hyperemia, were noted in the penguins of the current study. 12 Chronic uveitis was found in eyes concurrently affected by cataracts, which is consistent with LIU due to the leakage of soluble lens protein through an intact lens capsule. 14,15 The diagnosis of this type of uveitis is presumptive and is made on the observation of cataracts and the absence of other ocular or systemic disease.…”

“…Consistent with previous reports, all stages of cataracts were observed 6–9,12 . Incipient cataracts were the most frequent (38/73 eyes; 52.1%).…”

“…Anterior subcapsular cataracts were present in 5.5% of eyes with cataracts, again all incipient cataracts. In dogs, common sites for initial opacity development are at the equator, Y‐suture regions or anterior and posterior subcapsular, and depending on aetiology, they may or may not progress 12 . Thus, periodic evaluation of these eyes would be very interesting to determine the progression of the cataract.…”

Treatment with chloroquine is retinotoxic in captive African penguins (Speniscus demersus). Attenuation and recovery of electroretinographic responses

“…Baseline values for ophthalmic parameters, including intraocular pressure, Schirmer tear test, modified phenol red thread test, echobiometry, ocular surface bacterial flora and refractive error have previously been published for various penguin species 31‐34 . However to our knowledge, this is the first report of full‐field ERG recording in penguins.…”

Clinical ophthalmic parameters of the Quaker parrot (Myiopsitta monachus)

“…Reports of normative reference values for standard ophthalmic diagnostic tests in various avian species reveal wide species variation 10–36 . Normative measurements of the psittacine eye are limited to intraocular pressures of the budgerigar ( Melopsittacus undulatus ) and ring‐necked parakeet ( Psittacula krameri ) , while tear production and ocular ultrasound biometric values are reported for Amazon parrots ( Amazona aestiva ) 37,38 .…”