Megalocornea and anterior megalophthalmos (megalocornea spectrum) disorders are typically defined by corneal diameter > 12.5 mm in the absence of elevated intraocular pressure. Clinical features overlap with keratoglobus but are distinct from buphthalmos and severe (globus) keratoconus. Megalocornea spectrum disorders and keratoglobus are primarily congenital disorders, often with syndromic associations; both can present with large and thin corneas, creating difficulty in diagnosis, however, only keratoglobus is typically progressive. Molecular genetics provide significant insight into underlying aetiologies. Nonetheless, careful clinical assessment remains intrinsic to diagnosis. Surgical management can be challenging due to the enlarged ciliary ring and weakened zonules in megalocornea spectrum disorders and the extreme corneal thinning of keratoglobus. In this review, the established literature on measurement of corneal diameter, diagnosis of megalocornea, anterior megalophthalmos and keratoglobus, differentiation from severe keratoconus, recent molecular genetics research and key surgical modalities in the management of these rare disorders are outlined and discussed.

中文翻译：

---

巨角膜、前巨眼、角膜球和相关的眼前节疾病：综述

巨角膜和前巨眼（巨角膜谱）疾病通常定义为角膜直径 > 12.5 mm，但眼内压不升高。临床特征与球状角膜重叠，但不同于眼眶和严重（球状）圆锥角膜。巨角膜系疾病和角膜球主要是先天性疾病，通常与综合征相关；两者都可能出现大而薄的角膜，造成诊断困难，但是，只有角膜球通常是进行性的。分子遗传学提供了对潜在病因的重要洞察。尽管如此，仔细的临床评估仍然是诊断的本质。由于巨角膜谱系疾病中的睫状环扩大和小带减弱以及角膜球的角膜极度变薄，手术治疗可能具有挑战性。在这篇综述中，概述和讨论了关于测量角膜直径、诊断巨角膜、前部巨眼球和角膜球、与严重圆锥角膜的鉴别、最近的分子遗传学研究和治疗这些罕见疾病的关键手术方式的既定文献。