Contact lens‐related complications
Authors: Costa Celso 
Published: January 2024

The use of contact lens is very popular and its global market is growing. They have numerous applications, some well‐established and others still not consensual but which have been gaining more and more approval, namely refractive errors, dry eye management, post refractive surgery rehabilitation, persistent epithelial defects, cosmetic approaches and drug delivery systems. Unfortunately, there are some complications caused by their use, some of them sight threatening. The purpose of this presentation is to review these problems and to provide a better understanding of them.The major mechanisms implicated are numerous: trauma, decreased corneal oxygenation, reduced corneal and conjunctival lubrication, allergic and inflammatory responses and infection. However, depending on the complication we are talking about, there are other factors involved, such as contact lens‐related factors (material, design, fit and wearing schedule) and environmental factors (ocular surface condition, external environment, occupational factors, medications and compliance).The symptomatology experienced by patients ranges from hypoesthesia and mild conjunctival hyperemia to photophobia, contact lens intolerance and even decreased visual acuity.Many complications have been described. The most important (most common or most serious) are contact lens discomfort (CLD), dry eye, corneal deepithelialization (CD), sterile infiltrates (SI), corneal neovascularization (CNV), infectious keratitis (IK) and giant papillary conjunctivitis (GPC). Superior epithelial arcuate lesion, contact lens‐related peripheral ulcer, corneal distortion, hypoesthesia, ptosis, pinguecula, corneal edema, allergy aggravation, herpes reactivation and endothelial changes have also been described.CLD is an episodic or persistent adverse ocular sensation related to lens wear with a variable incidence in the literature, ranging from 23% to 94% in different series, being less common with soft lenses. Dry eye plays its role acting as a risk factor for CLD and/or as a consequence of contact lens use. CD manifests as punctate epithelial keratopathy, epithelial abrasions, foreign body tracks, corneal dellen, microcysts, vacuoles, mucin balls and dimple veiling. GPC is one of the most common adverse effects of contact lenses and the papillary reaction of the upper tarsal conjunctiva is the main feature of this entity. CNV is the formation of new vessels basically found in capillaries and venules of the pericorneal plexus, which may progress to the corneal stroma. They are much more associated with soft contact lenses, especially in extended wearers. Of note, contact lens use is one of the most common causes of CNV usually highlighted. SI are the result of an immunological reaction, often do not contain overlying epithelial defect or anterior chamber reaction and may manifest as stromal deep opacities. IK may be caused by bacteria, viruses, fungus or parasites and prompt immediate care and close revaluations to anticipate disastrous outcomes.Conservative measures play a role in almost all complications and their prevention, such as patient education, lubrication, contact lens exchange when applicable and modification of environmental factors. Addressing and learning how to prevent or quickly diagnose all these complications is crucial to prevent serious consequences.