Gender differences in iridocorneal angle morphology: a potential explanation for the female predisposition to primary angle closure glaucoma in dogs

Abstract

Female dogs have a significantly smaller AOD vs. males. This difference may render the female iridocorneal angle more susceptible to closure and may partially explain the 2:1 female/male predisposition to PACG. Further studies using goniodysgenic dogs are warranted.

Microscopic Lesions in Canine Eyes with Primary Glaucoma

“…Although the mechanisms of glaucoma development are incompletely understood, GD is considered a cause of primary glaucoma in the dog, referred to here as GDAG 3 or PACG 3,10,15,[17][18][19][20] ; it has been referred to as GD-related glaucoma in one study. 4 GDAG/PACG is also known as primary open-angle closed-cleft glaucoma, 3,10,21 primary closed-angle glaucoma, or simply primary glaucoma.…”

Genetics of Canine Primary Glaucomas

“…9,11,128,141,143,157,158,165 Similar to PACG, a higher prevalence and severity of PLD as well as a narrower ICA opening are generally observed in female dogs. 131,138,141,148,158 In some breeds, such as the English springer spaniel, flat-coated retriever, Great Dane, Samoyed, and Shiba Inu, no predisposition for PLD and ICA opening based on sex was documented. 9,12,130,132,156 The inheritance of PLD and the width of the ciliary cleft opening were documented in several breeds, including English springer spaniel, 9 flat-coated retriever, 143,156 Great Dane, 132 and Samoyed.…”

“…141 Furthermore, female dogs tend to have a narrower ICA opening, which may predispose them to angle closure. 138 The pathogenesis of canine PACG is still not well understood. A narrow ICA and ciliary cleft are considered to be the prerequisite structural abnormality and are related to PLD.…”

“…Furthermore, without the additional assessment of the ciliary cleft width by high-resolution ultrasonography or ultrasound biomicroscopy, the examination of the ICA by gonioscopy alone may not provide a full picture about the status of the aqueous humor outflow pathways. 3,127,138 …”

“…133,134 Similar to human PACG, and in contrast to the tendency in POAG, female dogs are twice as likely to be affected as male dogs. 1,3,9,131,[134][135][136][137][138][139][140] The reasons for this difference are not well understood; it is possible that a shorter axial globe length in female compared with male dogs may result in a higher susceptibility for IOP to increase. 141 Furthermore, female dogs tend to have a narrower ICA opening, which may predispose them to angle closure.…”