Evaluation of ciliary cleft changes after phacoemulsification using ultrasound biomicroscopy in dogs with cataracts

Abstract

IntroductionGlaucoma is one of the most serious complications that causes irreversible blindness after phacoemulsification in dogs; however, a clear mechanism has not been elucidated. This study aimed to analyse the possible anatomical factors associated with glaucoma after phacoemulsification using parameters that reflect the anatomical characteristics of dogs.Materials and methodsA total of 69 eyes of 48 dogs were included in this study. The patients were divided into three groups: normal eye (n = 18), cataract (n = 39), and post-phacoemulsification for at least 2 months after surgery (post-phaco, n = 12). For further analysis, the dogs were subdivided into two groups according to cataract stage: phacoemulsification non-candidate and candidate groups. Non-cataracts and incipient cataracts were categorized into the non-candidate group, whereas immature and mature cataracts were categorized into the candidate group. Measurements of the ciliary cleft parameters, including the area of the ciliary cleft (CCA), length of the ciliary cleft (CCL), width of the ciliary cleft (CCW), iridocorneal angle, and angle opening distance, were obtained using ultrasound biomicroscopy.ResultsCCA, CCL, and CCW were significantly higher in the candidate group than in the non-candidate group. CCA, CCL, and CCW were significantly reduced in the post-phaco group compared to those in the cataract group. Based on these results, we found that the ciliary cleft expanded in cataract-affected eyes and narrowed after phacoemulsification. This may indicate that the space between the trabecular meshworks became narrower, potentially leading to an increase in the resistance of the aqueous humor.ConclusionA narrowed ciliary cleft after phacoemulsification may be an anatomical factor associated with glaucoma.

Ultrasound biomicroscopy analysis of ciliary muscle dynamics and its relation to intra-ocular pressure after phacoemulsification in dogs

“…These observations imply that as cataracts develop, the ciliary muscle tends to relax, leading to the outward movement of the ciliary body. Such findings align with prior research conducted in humans and support the hypotheses posited in our study ( 10 , 28 ). As cataracts progress, an increase in lens thickness and a corresponding rise in zonular fiber tension occur, resulting in a biologically relaxed state of the ciliary body ( 10 , 11 , 29 , 30 ).…”

“…In our previous paper, we proposed that prophylactic medications targeting AH production, such as beta-blockers and carbonic anhydrase inhibitors, may be helpful in reducing IOP elevation caused by CC narrowing after phacoemulsification ( 28 ). Furthermore, based on the findings of this study, it is estimated that drugs like phenylephrine, which relax the ciliary muscle by acting on the parasympathetic nervous system, could potentially be beneficial in this context ( 51 ).…”