A 37-year-old bull African elephant (
Lenticular abnormalities such as cataracts and lens luxation have been described in both Asian and African elephants [
Several methods used to surgically address cataracts in humans, wildlife, and domestic animals have been reported [
Keepers at the North Carolina Zoo (NCZ) reported that a 37-year-old, bull African elephant (
A complete ophthalmic examination was repeated six months later. The size of the cataracts had increased in both eyes and the elephant had an additional weight loss of 89 kg. A mature cataract was found in the right eye (Figure
Ophthalmic reexamination six months after the initial examination in 2010.
A mature cataract can be seen through the nondilated pupil in the right eye
The left lens was diagnosed with an incipient nuclear cataract during this reexamination
Ocular ultrasonography and electroretinography were performed to determine whether the elephant was a candidate for phacoemulsification and intraocular lens (IOL) implantation. Transcorneal B-scan ultrasonography revealed hyperechoic lens in both eyes, consistent with cataractous changes (Figure
B-mode ocular ultrasonography of the elephant’s right eye revealing a hyperechoic nuclear lens. Despite the clinical diagnosis of a mature cataract, the lens cortex appears to be less significantly affected in the ultrasound image. The crystalline lens thickness (A: 12.2 mm), crystalline lens diameter (B: 17.9 mm), and the vitreal chamber depth (C: 21.4 mm) are visible in this image, as well. Note that D is not a valid measurement and that the caliper measurements were inadvertently saved.
Unilateral phacoemulsification was chosen to remove the mature cataract in the right eye. Preoperative treatment with topical ophthalmic medications was implemented 24 hours prior to surgery. Medications were applied with a 1.0 ml syringe with the needless hub at a volume of 0.1 ml. These included 1.0% prednisolone acetate ophthalmic suspension (Omnipred, Alcon Laboratories, Inc., Fort Worth, Texas 76134) (q 30 minutes) to prevent endophthalmitis and reduce intraocular inflammation, 0.5% moxifloxacin hydrochloride ophthalmic solution (Vigamox, Alcon Laboratories, Inc., Fort Worth, Texas 76134) (q 30 minutes) to prevent endophthalmitis, and 1.0% nepafenac ophthalmic suspension (Nevanac, Alcon Laboratories, Inc., Fort Worth, Texas 76134) (q 12 hours) to control intraocular inflammation prior to surgery.
The elephant was induced with etorphine (1.5
The original plan was to perform surgery on the right eye, if possible, but the elephant went into right lateral recumbency and could not be maneuvered into left lateral recumbency. As a result, surgery was performed on his left eye.
A size 30 endotracheal tube is being placed, under manual control, along the left arm of this veterinarian.
A modified Y-piece apparatus and electric leaf blower were attached to the endotracheal tube to provide intermittent positive pressure ventilation (IPPV) and supplemental oxygen to the elephant bull during the duration of the anesthesia.
A modified retrobulbar block was performed following aseptic preparation of the periocular region and bulbar conjunctiva. Using a 19-gauge, 2.5-inch spinal needle with a slight bend, approximately 25 ml of 2% mepivacaine (Pharmacia & Upjohn Company, Pfizer Inc. NY, NY, USA) was deposited behind the globe from both dorsal and temporal conjunctival access points (Figure
A modified retrobulbar block was performed using a slightly bent, 19-gauge, 2.5-inch needle to deposit approximately 25 ml of 2% mepivacaine (Pharmacia & Upjohn Company, Pfizer Inc. NY, NY, USA) through the ventral and dorsal bulbar conjunctiva behind the globe.
Manual digital pressure was applied simultaneously to the upper and lower eyelids to displace the globe anteriorly, thereby providing better access to the sites of injection for the modified retrobulbar block described and shown in Figure
Due to the unconventional head position and limited access to the globe, a head-mounted microscope (Varioscope M5®, Acrivet, Veterinary Division of S&V Technologies AG, Hennigsdorf, Germany) was utilized (Figure
Due to the unconventional surgical location and positioning of the elephant, a head-mounted microscope (Varioscope M5®, Acrivet, Veterinary Division of S&V Technologies AG, Hennigsdorf, Germany) was utilized to facilitate visualization for the procedures.
Phacoemulsification was performed using a 45-degree, 4 cm long handpiece designed specifically for horses (Acrivet, Veterinary Division of S&V Technologies AG, Hennigsdorf, Germany).
The elephant was given naltrexone (500 mg IM, 500 mg IV) to reverse the effects of the etorphine and extubated. The animal became aroused and began moving his head within two minutes of receiving the injection. He was moderately disoriented and unable to rise on his own, requiring assistance with an overhead hoist (Figures
A series of images illustrating the use of an overhead hoist attached to a sling that was placed under his thorax prior to induction (see Figure
The elephant improved in attitude and activity level immediately following surgery and was able to navigate the holding area without issue, despite his being more than 9.00 diopters (D) hyperopic due to his being left aphakic postoperatively. All ophthalmic treatments were continued, as prescribed, for a total of 30 days. Thereafter, the medication frequencies were serially decreased at two-week intervals until they were discontinued 16 weeks after surgery. Due to the bull’s continued increase in appetite and improved ability to navigate the area in the barn, he was returned to the habitat approximately one month postoperatively. Three months after the initial surgery in the left eye, a full ophthalmic exam was performed. The left eye appeared to be stable and healing well after recovery. Ocular ultrasound of the right eye showed that the cataract had progressed and a ventral lens subluxation had developed. Topical therapy to constrict the pupil and prevent increased intraocular pressure of the right eye included latanoprost 0.01% ophthalmic solution (Bausch and Lomb, Bridgewater, NJ, 08807) (q 6 hours for 30 days) and pilocarpine hydrochloride 2% solution (Akorn Animal Health, Lake Forest, IL 60045) subconjunctivally (q 6 hours until time of surgery).
Preoperative topical medications were started three days prior to the planned phacoemulsification of the right eye. These included 1.0% prednisone acetate ophthalmic solution (q 12 hours) to prevent endophthalmitis and reduce intraocular inflammation, 0.5% moxifloxacin hydrochloride ophthalmic solution (q 8 hours) to prevent endophthalmitis, and 1.0% nepafenac ophthalmic suspension (q 12 hours) to control intraocular inflammation prior to surgery.
To prevent the elephant from going down into right lateral recumbency, it was trained to stretch out in left lateral recumbency (Figure
The elephant bull was photographed during a training session where he was practicing to lie down in left lateral recumbency on command, with the hope that he would end up in the appropriate position to perform phacoemulsification of his right eye.
The elephant was examined two weeks postoperatively and a complete ophthalmic examination was performed. Menace response, palpebral reflex, dazzle reflex, and pupillary light reflexes were present in both eyes. IOP in both eyes were within normal limits and the incision sites appeared to be healing well. The elephant was cleared to be let out into his habitat but was started on atropine ophthalmic solution (Akorn Animal Health, Lake Forest, IL 60045) 1 drop q 12 hours for 3 days.
Complete ophthalmic examinations were repeated at 3 weeks, 8 weeks, 12 weeks, 6 months, and 12 months. At the 8-week recheck, a small lens remnant was discovered in the vitreous in the right eye that could only be visualized when the pupil was fully dilated (Figure
A small piece of what appears to be lens nuclear material can be visualized within the ventromedial pupil at approximately the 4 o’clock position.
A corrective contact lens (+ 9.00 diopters) has been placed in the elephant’s right eye in an attempt to correct the marked hyperopia due to his being left aphakic (Acrivet, Veterinary Division of S&V Technologies AG, Hennigsdorf, Germany). Note the smaller circular area within the center of the lens (this is most readily visible along the ventromedial pupil extending from approximately 2:30 to 9:00 o’clock) that represents the corrective portion of the lens. The four black dots at the 12, 3, 6, and 9 o’clock edges of the corrective contact lens are to make it easier to visualize during subsequent examinations.
Cataracts are a common finding in many domestic species and are occasionally seen in African elephants (
Previously published methods for cataract removal in domestic and nondomestic species include lensectomy and phacofragmentation. A lensectomy, where the entire lens is removed, often requires multiple or larger incisions, which increases the potential damage to the anterior and posterior capsules and therefore exacerbates postsurgical complications in healing and recuperation [
Utilizing a trilaminar (three‐step) corneal incision, whereby a proximal hinge is created at the base of the incision, helps to prevent the incision from leaking. This technique is advantageous in the horse, since it prevents the iris/corpora nigra from migrating to the corneal incision during phacoemulsification of the lens and aspiration of the cortex [
Following bilateral phacoemulsification and irrigation/aspiration, the elephant bull was able to navigate his surroundings, forage normally, and be reintegrated into the herd, thereby improving his quality of life. Four years postoperatively, the elephant had mild visual impairment, but a normal attitude and mentation for an adult bull elephant. He weighed 5,515 kg, 88kg more than at the time of the second surgery, and attained a normal body condition score for a bull elephant of his age. The rapid postoperative recovery of the elephant following phacoemulsification and his quick acclimation to navigating and foraging after recovery indicated that this surgical procedure, with proper planning and execution, can be a safe and effective treatment for cataracts in adult elephants. Regular ophthalmic examination in elephants should be included in their annual health check program. Early detection and treatment of any ocular abnormality may avoid the development of subsequent irreversible ocular pathology.
The authors declare that they have no conflicts of interest.
The authors would like to thank everyone involved in making both of these surgeries a success.