Dry Eye Disease After Refractive Surgery

The Incidence and Risk Factors for Dry Eye After Pediatric Strabismus Surgery

INTRODUCTION

This study aimed to investigate the incidence and risk factors for dry eye after pediatric strabismus surgery.

METHODS

Children aged 5-12 years who underwent strabismus surgery were included in this single-center, prospective, cohort study. The ocular surface assessments were conducted 1 day before and 1, 4, and 8 weeks after surgery. The main outcome measures were the incidence of dry eye after strabismus surgery and associated risk factors.

RESULTS

A total of 84 eyes (48 children) that underwent strabismus surgery were included in the study. The mean age at surgery was 7.21 years. The incidence of dry eye was 47.62% at 1 week, 10.71% at 4 weeks, 0% at 8 weeks after surgery. The preoperative tear breakup time (BUT) was lower in the dry eye group than that in the non-dry eye group (P ≤ 0.01). The univariate analysis showed that preoperative BUT was significantly associated with the incidence of dry eye after pediatric strabismus surgery (odds ratio [OR] 0.647, confidence interval [CI] 0.503-0.833, P ≤ 0.01).

CONCLUSIONS

Dry eye commonly occurs after pediatric strabismus surgery. Tear film instability is more common than deficient aqueous tear production in patients with dry eye after surgery. Children with a low preoperative BUT are more likely to develop dry eye after strabismus surgery.

Post-LASIK dry eye disease: A comprehensive review of management and current treatment options

Laser-assisted in situ keratomileusis (LASIK) is a unique corneal stromal laser ablation method that uses an excimer laser to reach beneath corneal dome-shaped tissues. In contrast, surface ablation methods, such as photorefractive keratectomy, include removing epithelium and cutting off the Bowman's layer and the stromal tissue of the anterior corneal surface. Dry eye disease (DED) is the most common complication after LASIK. DED is a typical multi-factor disorder of the tear function and ocular surface that occurs when the eyes fail to produce efficient or adequate volumes of tears to moisturize the eyes. DED influences quality of life and visual perception, as symptoms often interfere with daily activities such as reading, writing, or using video display monitors. Generally, DED brings about discomfort, symptoms of visual disturbance, focal or global tear film instability with possible harm to the ocular surface, the increased osmolarity of the tear film, and subacute inflammation of the ocular surface. Almost all patients develop a degree of dryness in the postoperative period. Detection of preoperative DED and committed examination and treatment in the preoperative period, and continuing treatments postoperatively lead to rapid healing, fewer complications, and improved visual outcomes. To improve patient comfort and surgical outcomes, early treatment is required. Therefore, in this study, we aim to comprehensively review studies on the management and current treatment options for post-LASIK DED.

In vivo confocal microscopy of sub-basal corneal nerves and corneal densitometry after three kinds of refractive procedures for high myopia

PURPOSE

To observe corneal nerve fibers and densitometry after small incision lenticule extraction (SMILE), femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) and laser-assisted subepithelial keratomileusis (LASEK) for high myopia.

METHODS

This is a prospective, cross-sectional research study. Patients with high myopia (equivalent spherical lens: -6.00 and -11.00D) who underwent laser corneal refractive surgery were divided into three groups: SMILE, FS-LASIK and LASEK. Scheimpflug imaging of corneal nerves in five areas was observed by confocal microscopy before and 6, 12 months after surgery. Corneal densitometry was measured by Pentacam anterior segment analysis system.

RESULTS

Overall, 59 patients were enrolled. The nerve density in the central area did not recover to the preoperative level in three groups until 12 months. The density and length of corneal nerves in central and lower area were better in the SMILE group 6 months postoperatively (p = 0.01), while nerve density did not differ significantly among three groups 12 months postoperatively (p = 0.18). Nerve fibers in central and temporal region were wider in LASEK than that in other two groups at 6- and 12-month follow-up. Corneal densitometry in the central 6 mm diameter was significantly higher in the LASEK group compared with other two groups 6 months postoperatively (p = 0.04). Twelve months postoperatively, corneal densitometry in range of all zone was lower in SMILE than in FS-LASIK and LASEK (p = 0.01, 0.03, 0.04).

CONCLUSIONS

Compared with FS-LASIK and LASEK, SMILE-treated eyes with high myopia had certain advantages in nerve density, length and nerve connection way and had better corneal transparency after operation.

Attrition und Osmokinetik – Zwei Konzepte zur Pathogenese des Trockenen Auges

Die neuen Erkenntnisse der Pathophysiolgie des Trockenen Auges erkennen das Zusammenspiel von Tränen, Augenoberfläche und Lidoberfläche als eine funktionelle Einheit an. Der Begriff der Benetzungsfähigkeit der Tränen in Abhängigkeit der mikrotektonischen Anatomie der Augenoberfläche relativiert die Anforderungen an Träne und Tränenersatzmittel. Das Model der Attrition, welches die Effekte der friktionsneutralisierenden Kapazität des Tränenfilms, der Reibung und die Bedeutung der Mechanotransduktionskapazität des Epithels zusammenfasst, wird eingeführt und dessen pathophysiologische Bedeutung erläutert. Attrition und Benetzung bestimmen zusammen grundlegende pathophysiologische Vorgänge in der Augenoberfläche wie Aktivierung von Nerven (subjektive Beschwerden) sowie Entzündung und beeinflussen damit die Dynamik der Pathophysiologie, und den Übergang von vorübergehenden Beschwerden zu einer manifesten Erkrankung des Trockenen Auges. Die Betrachtung der Osmolarität als numerischer statischer Grenzwert zur alleinigen Diagnose des Trockenen Auges ist klinisch nicht haltbar. Das neue, dynamische Model der Osmokinetik, zeigt dagegen eine Alternative auf, in der die Tageschwankungen und die Beachtung des durchschnittlichen Osmolaritätsniveaus gröβere Bedeutung gewinnen und damit der eigentlichen pathophysiologischen Bedeutung der Osmolarität gerechter wird.

Oral Aminoacids Supplementation Improves Corneal Reinnervation After Photorefractive Keratectomy: A Confocal-Based Investigation

Aim of this retrospective study was to estimate the effect of oral supplementation with amino acids (AA) on corneal nerves regrowth after excimer laser refractive surgery with photorefractive keratectomy (PRK). Based on the pre and post-surgical treatment received, 40 patients with 12 months of follow-up were distributed in two groups: 20 patients had received oral AA supplementation 7 days before and 30 days after PRK, and 20 patients without AA supplementation, as untreated reference control. All patients followed the same standard post-operative topical therapy consisting of an association of antibiotic and steroid plus sodium hyaluronate during the first week, then steroid alone progressively decreasing during 30 days and sodium hyaluronate for the following 3 months. In vivo corneal confocal microscopy was used to evaluate the presence of sub-basal corneal nerve fibers during 12 months after PRK. Results have shown that sub-basal nerves regenerated significantly faster (p <0.05), and nerve fibers density was significantly higher (p <0.05) with a more regular pattern in the eyes of AA treated patients with respect to the untreated control group. Therefore, our data indicate that oral supplementation with AA improved significantly corneal nerve restoration after PRK and could thus be considered as an additional treatment during corneal surgical procedures.

Neurotrophic keratopathy and refractive surgery

PURPOSE OF REVIEW

Corneal nerve function is an important consideration for the refractive surgeon. In patients without a history of neuropathy, refractive surgery can lead to destruction of corneal nerves and may predispose to keratopathy. The purpose of this review is to provide an update on the effect of refractive surgery on corneal nerve function and the potential for an increased risk of neurotrophic keratopathy development.

RECENT FINDINGS

Recent studies have reinforced that refractive surgery can cause anatomical and functional changes in corneal nerve function. Among the most commonly performed refractive surgery procedures are Laser Assisted In-situ Keratomileusis, Photorefractive Keratectomy, and Small Incision Lenticule Extraction. Due to differences in technique, these procedures can have varying effects on corneal nerve structure. Using in vivo confocal microscopy, postrefractive patients were found to have decreased total nerve density when compared with controls in the immediate postoperative period. In some studies, patients have been shown to undergo re-innervation and regain significant amounts of nerve function. The majority of studies have found that despite decreased nerve cell density, long-term outcomes of refractive surgery patients are generally favorable. However, loss of corneal nerve function can lead to a variety of serious effects ranging from dry eye disease, corneal hypoesthesia/anesthesia, neuropathic pain, to neurotrophic keratopathy and ulceration in the rare cases.

SUMMARY

Neurotrophic keratopathy is a rare occurrence after keratorefractive surgery and is largely due to damage to corneal nerves. Proper patient selection and counseling are essential to decrease the risk of development of this devastating complication.

[Regression and ablation profiles in corneal refractive surgery]

Regression after corneal refractive surgery is a complex phenomenon which seems inevitable. The choice of surgical technique has very little influence on regression for low myopia or myopic astigmatism. However, LASIK and SMILE are the two techniques of choice in the correction of high myopia. LASIK is also better for the correction of hyperopia, hyperopic astigmatism and mixed astigmatism. Intraoperatively, the choice of a wide optical zone and adherence to a thick residual stromal bed provide stability. Regression may also be reduced by modulating anti-inflammatory therapy, treating dry eye, and using mitomycin C in PKR. In all cases, obtaining keratometry during patient follow-up helps to identify the cause of the regression. The objective of this review is to synthesize recent data from the literature on regression in refractive surgery as a function of the ablation profiles used.

Study of tear film optics and its impact on quality of vision

Purpose:

To evaluate the relation of the tear film on the quality of vision comparing parameters in normal patients to those having dry eye disease.

Methods:

50 normal and 50 eyes with dry eye disease (DED) were included in the study. Patients were screened for dry eye with Schirmer's test, tear break up time, ocular surface staining, and assessment of meibomian gland disease. Their quality of vision was assessed using the Optical quality analysis system (OQAS). The results of dry eye evaluation were correlated with the parameters on the OQAS especially the mean objective scatter index (OSI).

Results:

Patients with dry eye and unstable tear film were found to have a significantly worse quality of vision and optical scatter (P < 0.05). They were also noted to have fluctuation of vision between blinks.

Conclusion:

Tear film optics can have an important bearing on the quality of vision and quality of life. A detailed assessment preoperatively will help improve surgical outcomes and patient satisfaction.

Association of Dry Eye Disease With Dyslipidemia and Statin Use

PURPOSE

To determine whether an association exists between dry eye disease (DED) and statin use and/or dyslipidemia.

DESIGN

Retrospective, case-control study.

METHODS

Setting: University of North Carolina (UNC)-affiliated healthcare facilities.

STUDY POPULATION

72,931 patients seen at UNC ophthalmology clinics over a 10-year period.

MAIN OUTCOME MEASURES

Odds ratios (ORs) calculated between DED and a history of low, moderate, or high-intensity statin use; and ORs calculated between DED and abnormal lipid panel values.

RESULTS

Total of 39,336 individuals (53.9% female) were analyzed after exclusion of individuals with confounding risk factors for DED. Of these, 3,399 patients (8.6%) carried a diagnosis of DED. Low-, moderate-, and high-intensity statin regimens were used by 751 subjects (1.9%), 2,655 subjects (6.8%), and 1,036 subjects (2.6%). Lipid abnormalities were identified as total cholesterol >200 mg/dL, 4,558 subjects (11.6%); high-density lipoprotein (HDL) <40 mg/dL, 2,078 subjects (5.3%); low-density lipoprotein (LDL) >130 mg/dL, 2,756 subjects (7.0%); and triglycerides (TGs) >150 mg/dL, 2,881 subjects (7.3%). The odds ratios (OR) of carrying a diagnosis of DED given the presence of low-, moderate-, and high-intensity statin use were 1.39 (95% confidence interval [CI]: 1.13-1.72); OR 1.47 (95% CI: 1.30-1.65), and OR 1.46 (95% CI: 1.21-1.75), respectively. The OR of carrying a diagnosis of DED given the presence of total cholesterol >200 mg/dL, HDL <40 mg/dL, LDL >130 mg/dL, and TGs >150 mg/dL were 1.66 (95% CI: 1.52-1.82), 1.45 (95% CI: 1.26-1.67), 1.55 (95% CI: 1.39-1.74), and 1.43 (95% CI: 1.27-1.61), respectively.

CONCLUSIONS

A history of statin use or dyslipidemia is associated with an increased odds of having a DED diagnosis. Further studies are needed to determine whether statin use and/or dyslipidemia increases the risk of DED.

Isotretinoin and the eye: A review for the dermatologist

Due to the prevalence of acne vulgaris, isotretinoin is one of the most prescribed drugs among physicians and dermatologists. Although exhibiting an adequate safety profile, adverse events secondary to isotretinoin use are common. Before prescribing isotretinoin, physicians usually inquire about pregnancy and perform serologic tests including cholesterol, triglycerides, and liver enzymes. Ocular manifestations are commonly neglected. Despite being generally mild, ocular manifestations related to either topical or systemic isotretinoin may cause important ocular morbidity. The ocular surface is the most affected site within the eye; however, retinal and optic nerve disease also have been documented. Evaporative dry eye disease, which may range from mild to severe, is the most common adverse ocular effect associated with isotretinoin use. The aim of this review is to present an up-to-date overview for the dermatologist about the prevention, diagnosis, and treatment of the ocular side effects of isotretinoin, and when to refer to the eye specialist.

Relationship between lipid layer thickness, incomplete blinking rate and tear film instability in patients with different myopia degrees after small-incision lenticule extraction

Objective

To elucidate the relationship between lipid layer thickness (LLT), incomplete blinking rate and tear film stability in patients with different myopia degrees after small-incision lenticule extraction (SMILE) and to determine whether there is a difference in the prevalence of dry eye disease (DED) after SMILE among patients with different myopia degrees.

Methods

Fifty patients (100 eyes) were enrolled in this study; they were divided into 3 groups according to the degree of spherical refraction: a low-myopia group (LMG; spherical refraction ≤-3.00 D, 20 eyes), a moderate-myopia group (MMG; -3.00 D < spherical refraction <-6.00 D, 40 eyes), and a high-myopia group (HMG; spherical refraction ≧-6.00 D, 40 eyes). Testing indicators included the ocular surface disease index (OSDI), fluorescein tear film breakup time (FBUT), corneal fluorescence staining (CFS), the Schirmer test (SI), lipid layer thickness (LLT), blink rate (BR) per 20 seconds, incomplete blinking rate, noninvasive keratograph assessment of first and average tear film breakup time (NIKBUT_f, NIKBUT_av), and tear meniscus height (TMH). Each indicator was evaluated preoperatively and postoperatively at 1 w, 1 mo and 3 mo.

Results

The mean age was 29.12±5.95 years. There were no significant differences among the three groups (p>0.05), except preoperative age (p = 0.006). There were significant differences in the FBUT among the three groups at postoperative 1 w and 1 mo (p<0.05). There were significant differences in the incomplete blinking rate and FBUT between the LMG and the HMG at postoperative 1 mo (p<0.05). The number of first tear film breakup points located beyond the 6 mm diameter of the cornea was higher in the HMG than in the other groups. The prevalence of DED in the LMG, the MMG, the HMG was 15%, 8% and 23%, respectively, at 1 w postoperative and 30%, 45% and 53%, respectively, at postoperative 1 mo. The change in LLT was significantly correlated with the changes in FBUT (r = 0.408, p<0.001) and incomplete blinking rate (r = -0.266, p = 0.007). The change in OSDI was negatively correlated with the change in SI (r = -0.502, p = 0.000).

Conclusions

The changes in LLT and incomplete blinking rate decreased the stability of the tear film. The changes in LLT, FBUT and incomplete blinking rate differed postoperatively with different myopia degrees. The prevalence of DED was higher in the HMG than in the other two groups.

Corneal nerve healing after in situ laser nerve transection

Purpose

We have previously reported that lamellar dissection of the cornea transects stromal nerves, and that regenerating neurites form a dense net along the surgical plane. In these experiments, we have disrupted the stromal nerve trunks in situ, without incising the cornea, to determine the regeneration events in the absence of a surgical plane.

Methods

Thy1-YFP mice were anesthetized and in vivo images of the corneal nerves were obtained with a wide-field stereofluorescent microscope. A far infrared XYRCOS Laser attached to 20X objective of an upright microscope was used to perform in situ transection of the stromal nerves. 3 types of laser transections were performed (n = 5/group): (i) point transection (a single cut); (ii) segmental transection (two cuts enclosing a segment of nerve trunk); and (iii) annular transection (cuts on all nerve trunks crossing the perimeter of a 0.8 mm diameter circular area centered on the corneal apex). Mice were imaged sequentially for 4 weeks thereafter to assess nerve degeneration (disappearance or weakening of original fluorescence intensity) or regeneration (appearance of new fluorescent fronds). Beta-3-tubulin immunostaining was performed on corneal whole-mounts to demonstrate nerve disruption.

Results

The pattern of stromal nerves in corneas of the same mouse and in corneas of littermates was dissimilar. Two distinct patterns were observed, often within the same cornea: (i) interconnected trunks that spanned limbus to limbus; or (ii) dichotomously branching trunks that terminate at the corneal apex. Point transections did not cause degeneration of proximal or distal segment in interconnected trunks, but resulted in degeneration of distal segment of branching trunks. In segmental transections, the nerve segment enclosed within the two laser cuts degenerated. Lack of beta-3 tubulin staining at transection site confirmed nerve transection. In interconnected trunks, at 4 weeks, a hyperfluorescent plaque filled the gap created by the transection. In annular transections, some nerve trunks degenerated, while others regained or retained fluorescence.

Conclusions

Interconnected stromal nerves in murine corneas do not degenerate after in situ point transection and show evidence of healing at the site of disruption. Presence or absence of a surgical plane influences corneal nerve regeneration after transection.

Corneal re-innervation following refractive surgery treatments

Laser refractive surgery is one of the most performed surgical procedures in the world. Although regarded safe and efficient, it has side effects. All of the laser based refractive surgical procedures invoke corneal nerve injury to some degree. The impact of this denervation can range from mild discomfort to neurotrophic corneas. Currently, three techniques are widely used for laser vision correction: small incision lenticule extraction, laser-assisted keratomileusis in situ and photorefractive keratotomy. Each of these techniques affects corneal innervation differently and has a different pattern of nerve regeneration. The purpose of this review is to summarize the different underlying mechanisms for corneal nerve injury and compare the different patterns of corneal reinnervation.

TFOS DEWS II Sex, Gender, and Hormones Report

One of the most compelling features of dry eye disease (DED) is that it occurs more frequently in women than men. In fact, the female sex is a significant risk factor for the development of DED. This sex-related difference in DED prevalence is attributed in large part to the effects of sex steroids (e.g. androgens, estrogens), hypothalamic-pituitary hormones, glucocorticoids, insulin, insulin-like growth factor 1 and thyroid hormones, as well as to the sex chromosome complement, sex-specific autosomal factors and epigenetics (e.g. microRNAs). In addition to sex, gender also appears to be a risk factor for DED. "Gender" and "sex" are words that are often used interchangeably, but they have distinct meanings. "Gender" refers to a person's self-representation as a man or woman, whereas "sex" distinguishes males and females based on their biological characteristics. Both gender and sex affect DED risk, presentation of the disease, immune responses, pain, care-seeking behaviors, service utilization, and myriad other facets of eye health. Overall, sex, gender and hormones play a major role in the regulation of ocular surface and adnexal tissues, and in the difference in DED prevalence between women and men. The purpose of this Subcommittee report is to review and critique the nature of this role, as well as to recommend areas for future research to advance our understanding of the interrelationships between sex, gender, hormones and DED.

Photorefractive keratectomy for patients with preoperative low Schirmer test value

Purpose

To compare dry eye signs and symptoms between patients with preoperative low and normal Schirmer test after Photorefractive keratectomy (PRK).

Methods

In this prospective, nonrandomized, comparative case series, 76 eyes of 76 patients were preoperatively categorized into two groups according to selected criteria for characterization of tear film status: the low Schirmer test value (STV) group and the normal STV group. For the tear function assessment, we performed a Schirmer test with and without anesthesia, tear break-up time (TBUT) test, and measurement dry eye symptoms using the Farsi translation of Ocular Surface Disease Index (OSDI) questionnaire pre- and 3 months post-operation.

Results

Postoperatively, the Schirmer and TBUT values were significantly lower in both groups than preoperatively (all p < 0.05). Deterioration in tear secretion was significantly greater in the low STV group (p = 0.012), but tear stability was more compromised in the normal STV group (p = 0.021). The changes in OSDI score were not significant between the two groups.

Conclusion

These results demonstrated that tear function deteriorates after PRK. Therefore, patients with low preoperative Schirmer test values should be thoroughly assessed for dry eye before proceeding with refractive surgery to eliminate postoperative complication.