McMonnies Charles W
Honorary Professor, School of Optometry and Vision Science, University of New South Wales, 77 Cliff Avenue, Northbridge, Sydney, Kensington, New South Wales 2052 Australia.
Eye Vis (Lond). 2020 Feb 1;7:6. doi: 10.1186/s40662-019-0172-z. eCollection 2020.
Dry eye disease aetiologies can be classified dichotomously into aqueous deficient and evaporative types although many cases involve combinations of both. Differential diagnosis can be confounded by some features of dry eye disease being common to both aetiologies. For example, short tear break-up times are prime diagnostic findings of tear instability due to lipid and/or mucin deficiencies, but thin tear layers in aqueous deficient eyes also shorten tear break-up times, even at normal range rates of evaporation in eyes without lipid and/or mucin deficiencies. Because tear instability and short tear film break-up times due to thin tear layers can be independent of lipid and/or mucin deficiency, aqueous deficiency can be another form of evaporation-related dry eye. Conversely, tear layers which are thickened by punctal occlusion can be less susceptible to tear break-up. An inflamed lacrimal gland producing reduced quantities of warmer tears can be a basis for thin tear layers and tear instability demonstrated by shorter tear break-up times. Commonly used clinical tests for aqueous deficiency can be unreliable and less sensitive. Consequently, failure to detect or confirm aqueous deficiency as a contributor to short tear break-up times could result in too much weight being given to a diagnosis of meibomian gland deficiency. Less successful treatment outcomes may be a consequence of failing to detect aqueous deficiency. Refining disease classification by considering aqueous deficiency as a contributor to, or even a form of evaporation-related dry eye, could be the basis for more comprehensive and appropriate treatment strategies. For example, some treatment methods for evaporation-related dry eye might be appropriate for aqueous and mucin-deficient as well as lipid-deficient dry eyes. Anti-inflammatory treatment for the lacrimal gland as well as the conjunctiva, may result in increased aqueous production, reduced tear temperature, tear instability and evaporation rates as well as lower osmolarity.
干眼疾病的病因可分为水液缺乏型和蒸发过强型两类，不过许多病例是两者兼而有之。由于干眼疾病的某些特征在这两种病因中都很常见，因此鉴别诊断可能会受到混淆。例如，泪膜破裂时间短是脂质和/或黏蛋白缺乏导致泪液不稳定的主要诊断依据，但水液缺乏型干眼的泪膜层薄也会缩短泪膜破裂时间，即使在没有脂质和/或黏蛋白缺乏的眼睛中，正常蒸发速率下也是如此。由于泪膜层薄导致的泪液不稳定和短泪膜破裂时间可能与脂质和/或黏蛋白缺乏无关，水液缺乏可能是蒸发相关干眼的另一种形式。相反，泪小点阻塞导致泪膜层增厚可能不易出现泪膜破裂。泪腺发炎导致产生的温热泪液量减少，可能是泪膜层薄和泪膜破裂时间短所显示的泪液不稳定的原因。常用的水液缺乏临床检测方法可能不可靠且不太敏感。因此，未能检测或确认水液缺乏是短泪膜破裂时间的一个因素，可能会导致对睑板腺功能障碍的诊断权重过高。治疗效果不佳可能是未能检测到水液缺乏的结果。将水液缺乏视为蒸发相关干眼的一个因素甚至一种形式来完善疾病分类，可能是制定更全面、合适治疗策略的基础。例如，一些蒸发相关干眼的治疗方法可能适用于水液和黏蛋白缺乏以及脂质缺乏的干眼。对泪腺以及结膜进行抗炎治疗，可能会增加泪液分泌，降低泪液温度、泪液不稳定和蒸发速率以及渗透压。
