建立淚膜缺損相關乾眼症病變之紐西蘭白兔動物模式

Abstract

乾眼症（Dry eye disease, DED）又稱為Keratoconjunctivitis Sicca（KCS）為描述眼表因為多重因子所造成的淚腺功能異常，進而引起眼部不適的症狀、淚膜不穩定、嚴重甚至影響視力的疾病總稱，並且伴隨著淚膜滲透壓上升和眼部的炎症反應。此疾病為人類眼科學和獸醫眼科學上很常見的疾病。為了更瞭解這個疾病，有許多實驗動物模式曾嘗試被建立，以模擬出乾眼症的病生理特性，目前被廣泛使用過的物種包括小鼠、大鼠和兔子。本研究的目的即為嘗試建立淚膜缺損相關乾眼症病變之紐西蘭白兔動物模式，以作為後續實驗性治療乾眼症的可用模式。建立方式分為兩組，第一組為摘除全淚腺（Lacrimal glands）、哈得氏腺（Harderian gland）和第三眼瞼（Nictitating membrane）。第二組為摘除全淚腺（Lacrimal glands）、哈得氏腺（Harderian gland）和第三眼瞼（Nictitating membrane）之外，另外加上以濃度50%的三氯乙酸（Trichloroacetic acid）做結膜化學燒灼。評估乾眼症方式為術後每週追蹤Schirmer’s test (STT)、淚膜分解時間、螢光染色範圍、玫瑰紅染色範圍和淚液滲透壓。並於手術八週後做犧牲，進行角膜和結膜組織病理學分析。兩組結果在八週追蹤期間，皆可見顯著的淚水分泌量下降及淚膜分解時間下降。大多數術眼在螢光染色下呈現陽性點狀分佈的角膜糜爛病灶、玫瑰紅染劑也呈現陽性病灶。兩組皆呈現出淚液滲透壓上升趨勢且在組織病理學上出現角膜上皮厚度變薄之外，也皆出現明顯的杯狀細胞密度下降。本研究成功建立兩種穩定且具有高度再現性，不同程度的紐西蘭白兔乾眼症模式，提供後續其他學者對於該疾病的控制及治療上能夠有更多的研究機會。

Dry eye disease (DED), also called keratoconjunctivitis sicca (KCS), is a general term describing the abnormal function of the lacrimal glands caused by multiple factors on the ocular surface, which can cause eye discomfort, tear film instability, affect vision if too severe, and is accompanied by tear film osmolarity increase and inflammation of the eyes. DED is a very common disease in human ophthalmology and veterinary ophthalmology. In order to have a thorough understanding of this disease, various animal models have been established in order to mimic the diverse characteristics of DED, including mouse, rat, and rabbit. The aim of this study is to establish a stable rabbit model of DED by surgical removal of the lacrimal glands (LG), the harderian gland (HG), and the nictitating membrane (NM) with or without treating the bulbar conjunctiva with 50% trichloroacetic acid (TCA). Data from Schirmer’s test (STT), tear break-up time (TBUT), fluorescein stain (FS), rose bengal (RB) stain and tear osmolarity were collected as DED clinical parameters regularly each week and followed up for eight weeks post-operatively. On the post-operative eighth week, histopathologic analysis of the cornea and conjunctiva of the operated (right) and non-operated control (left) eyes was performed and the lesions of both groups were investigated. Both groups caused significant DED showing decreased STT and TBUT in the operated eyes. Most of the operated eyes revealed severe corneal punctate erosions with positive fluorescein stains and positive rose bengal stains. Increased tear osmolarity was also noted in both groups. In both groups, histopathology results showed a reduction of corneal thickness and a significant decrease of goblet cell number. This study successfully established two stable and reproducible models of dry eye in rabbits with different severity. These promising models can be used for further evaluation of novel treatment modalities for DED in humans and animals in the future.