A rabbit model for assessing symblepharon after alkali burn of the superior conjunctival sac

Abstract

Symblepharon due to chemical burns affects ocular surface health, and there are currently no satisfactory treatments. To improve our understanding of symblepharon, an appropriate animal model is urgently needed. We established a rabbit model of superior conjunctival sac alkaline burn to evaluate symblepharon severity. Alkali burns were induced in rabbits by contacting the superior conjunctival sac with 2 N NaOH-soaked semicircle filter paper (10 mm diameter) for 60 s, 90 s or 120 s. Clinical and histological features were examined, symblepharon severity was evaluated via conjunctival sac depth (grade I - IV) and volume measurements (grade a-d) post-injury at 4 weeks. With increasing alkali burn duration, corneal perforation and symblepharon severity increased. The 60 s group manifested a sub-conjunctiva scar. The 90 s group featured localized adhesion. The 120 s group was characterized by extensive scar hyperplasia and adhesion. The rabbit model exhibited stable and reliable symblepharon following an alkali burn of the superior conjunctival sac. For further research, 90 s is a suitable duration for conjunctival sac burn. The volume measured using conjunctival sac casting was considered when developing a successful evaluation system for symblepharon severity.

An eye on the dog as the scientist's best friend for translational research in ophthalmology: Focus on the ocular surface

“…In dogs, the conjunctival area is supposedly larger than in humans given the depth of the canine conjunctival fornices and the amount of conjunctiva covering the canine nictitating membrane, 76 although no objective data exist to date. In rabbits, the upper conjunctival fornix depth (20.36 mm) 36 is larger than in humans (15 mm), 35 while the conjunctival area is reportedly comparable (13.34–18.48 vs. 17.65 cm 2 , respectively), although the measurements did not include the rabbit's third eyelid (surgically removed by investigators) 37 …”

PNP Hydrogel Prevents Formation of Symblephara in Mice After Ocular Alkali Injury

“…Alkali has been used to injure the cornea in mice 9 , 11 , 13 ; however, these studies did not focus on the conjunctival effects as well as subsequent formation of symblephara. Prior studies have explored alkali injury on canine 25 and rabbit 26 conjunctiva using NaOH; however, genetic and therapeutic studies can be challenging in large animal models, in addition to the longer 4 to 5 weeks required for symblephara to develop. In our model, alkali injury caused the formation of symblephara with forniceal shortening without globe destruction within 7 days after injury.…”

“…An ideal animal model for symblephara should have tunable ocular surface injury without globe disruption and forniceal shortening due to adhesions. 26 One rabbit model of symblephara used a 10-mm filter paper crescent soaked in 2N NaOH for 90 seconds to induce symblephara. 26 In this study, symblephara formed in the late stages of alkali burns, around 4 weeks after NaOH injury, with fibroblast recruitment in the subconjunctival collagen fibers.…”

“…An alkali injury model described the formation of ocular symblephara in rabbits. 15 The rabbit ocular surface was injured with 2N NaOH for 90 seconds, and forniceal shortening and the formation of symblephara followed for 4 weeks. Although this model is useful for developing a basic understanding of the formation of symblephara, it may be difficult and expensive to use for high-throughput studies for testing therapeutics, with a long timeline until the formation of symblephara.…”

An Eye on the Dog as the Scientist’s Best Friend for Translational Research in Ophthalmology: Focus on the Ocular Surface

“…In dogs, the conjunctival area is supposedly larger than in humans given the depth of the canine conjunctival fornices and the amount of conjunctiva covering the canine nictitating membrane, 47 although no objective data exist to date. In rabbits, the upper conjunctival fornix depth (20.36 mm) 48 is larger than in humans (15 mm), 49 while the conjunctival area is reportedly comparable (13.34-18.48 vs. 17.65 cm 2 , respectively), although the measurements did not include the rabbit's third eyelid (surgically removed by investigators). 50 Conjunctival goblet cells are distributed individually in humans, dogs and rabbits, in contrast to clustered organization in mice and rats.…”