Corneal Refractive Surgery-related Dry Eye

Risk Factors and Management

Louis Tong; Yang Zhao; Ryan Lee

Expert Rev Ophthalmol. 2013;8(6):561-575.

Abstract and Introduction

Abstract

Dry eye is the most common post-operative complication in patients who undergo laser-assisted in situ keratomileusis and other photorefractive procedures. Epidemiological studies have found that almost all patients experience some form of dry-eye-related discomfort in the post-operative period. This review seeks primarily to identify patient factors, which predispose to this complication, as well as outline the possible interventions clinicians can consider to avoid, prevent and treat this complication. Numerous pre-, intra- and post-operative guidelines are provided. The ideal method of post-laser-assisted in situ keratomileusis dry eye prevention is a meticulous peri-operative management plan, as opposed to post-operative management alone. Newer modalities of photorefractive surgery may have differing effects on the ocular surface.

Introduction

Dry eye disease is defined as a multifactorial disease of the ocular surface and tear film that results in symptoms of discomfort, visual disturbance and tear film instability. It is characterized by hyperosmolarity of the tear film and inflammation of the ocular surface.^[1]

Photorefractive surgery induces dry eye or exacerbates pre-existing dry eye by causing increased tear osmolarity and inflammation of the ocular surface via various mechanisms.^[2] The three predominant techniques of photorefractive surgery now used in clinical practice are laser-assisted in-situ keratomileusis (LASIK), photorefractive keratectomy (PRK) and laser epithelial keratomileusis (LASEK). LASIK continues to be the most commonly performed surgery of the three.^[3] This discussion is hence centered upon LASIK, but still includes a study of some recent variants of laser corneal refractive procedures. While it is acknowledged that this topic has been extensively reviewed previously,^[4] this article focuses on providing concise, evidence-based guidelines to clinicians on how best to prevent or treat post-LASIK dry eye. This begins from a process of prudent patient selection combined with peri-operative treatment of the condition.

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Table 1. Studies investigating effect of hinge position on dry eye outcomes.
Study (year)	Sample size (eyes)	Hinge positions compared	Duration of follow-up (months)	Randomized or not	Corneal sensation	Schirmers test	TBUT	Corneal staining	Dry eye symptoms	Ref.
Donnenfeld et al. (2003)	104	Superior vs nasal	6	Yes	Worse in superior	No difference	No difference	Worse in superior	Not compared	[74]
Lee et al. (2003)	50	Superior vs nasal	6	Yes	Not compared	Worse in superior ^†	Worse in superior ^†	Not compared	Not compared	[76]
Huang et al. (2012)	86	Superior vs nasal	6	No	No difference	No difference	No difference	No difference	No difference	[78]
Mian et al. (2009)	56	Superior vs temporal	12	Yes	No difference	No difference	No difference	No difference	No difference	[79]
Vroman et al.(2005)	94	Superior vs nasal	6	Yes	No difference	No difference	No difference	No difference	No difference	[80]

^†Differences were observed at the 2-month interval after operation. Data at 6 months not reported.

Table 2. Table comparing different ablation laser platforms.
Study (year)	Laser systems compared	Sample size (number of eyes)	Duration of follow-up	Randomized or not	Dry eye parameters measured	Difference observed	Ref.
Flap creation laser platforms
Petznick et al. (2013)	Low-energy laser with corneal suction ^† versus high-energy laser with conjunctival suction ^‡	90	3 months	Randomized	Tear break-up time, Schirmer's test, corneal fluorescein staining, corneal sensitivity	None	[86]
Laser ablation platforms
Foo et al. (2011)	Conventional ^§ versus tissue-saving ^¶ versus wavefront-guided^#	72	3 months	Non-randomized	Tear lipid layer thickness ^‡‡, non-invasive tear break-up time ^‡‡, tear meniscus height	None	[88]
Moshirfaret al. (2011)	Wavefront-guided ^# versus wavefront-optimized ^††	44	3 months	Randomized	Schirmer's test	None	[87]