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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 33  |  Issue : 4  |  Page : 1226-1230

Optical coherence tomography in dry eye after laser in-situ keratomileusis with omega-3 supplementation


1 Department of Ophthalmology, Faculty of Medicine, Menofiya University, Dakahlia, Egypt
2 Department of Ophthalmology, Ministry of Health Hospitals (Meet Ghamr Hospital), Dakahlia, Egypt

Date of Submission13-Jul-2020
Date of Decision21-Aug-2020
Date of Acceptance02-Sep-2020
Date of Web Publication24-Dec-2020

Correspondence Address:
Amany M. E. Mohamed
MBBCh, Department of Ophthalmology, Ministry of Health Hospitals (Meet Ghamr Hospital), Meet Ghamr, Dakahlia
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/mmj.mmj_185_20

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  Abstract 


Background
Dry eye is the most common complication after laser in-situ keratomileusis (LASIK). Anterior segment optical coherence tomography (AS-OCT) is a noninvasive and quick clinical tool for the evaluation of a tear film. Oral omega-3 supplementation has been shown to improve nerve regeneration after injury to the cornea.
Aim
The aim of this work was to evaluate tear menisci parameters by AS-OCT in diagnosis of dry eye after LASIK procedure and evaluation of the role of oral omega-3 supplementation in the management of dry eye after LASIK.
Patients and methods
A prospective randomized study was performed on 50 participants who underwent LASIK procedure. These participants were further divided in two groups: the first group included 25 cases supplemented with omega-3 fatty acids, and the second group included 25 cases without omega-3 supplementation. The mean age of the studied patients with omega-3 administration was 33.2 ± 10.49 years, with a range from 19 to 45 years. Cases with any inflammatory pathology of the lid were excluded from the study.
Results
Upper tear meniscus height, upper tear meniscus depth, and upper tear meniscus area were statistically lower than lower tear meniscus height, lower tear meniscus depth, and lower tear meniscus area preoperatively and 1 day, 1 week, and 1 month postoperatively among the studied patients. Upper and lower tear menisci parameters were statistically higher inomega-3-treated group than control group preoperatively and at 1 day, 1 week, and 1 month postoperatively.
Conclusion
AS-OCT is considered a noninvasive approach to produce a tear meniscus image and a potential tool to diagnose dry eye after LASIK.

Keywords: anterior segment optical coherence tomography, dry eye, laser in-situ keratomileusis, omega-3


How to cite this article:
Nassar MK, Zaky MA, Mohamed AM. Optical coherence tomography in dry eye after laser in-situ keratomileusis with omega-3 supplementation. Menoufia Med J 2020;33:1226-30

How to cite this URL:
Nassar MK, Zaky MA, Mohamed AM. Optical coherence tomography in dry eye after laser in-situ keratomileusis with omega-3 supplementation. Menoufia Med J [serial online] 2020 [cited 2021 Apr 19];33:1226-30. Available from: http://www.mmj.eg.net/text.asp?2020/33/4/1226/304489




  Introduction Top


Laser in-situ keratomileusis (LASIK) is the most commonly performed refractive surgery procedure for the correction of myopia, hyperopia, and astigmatism. Dry eye is the most common early and late postoperative complication after LASIK[1].

Omega-3 fatty acids are essential fatty acids that cannot be synthesized by the body and need to be obtained by dietary means. These include alpha linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid. Potential benefits of omega-3 fatty acids have been documented in dry eyes of varied etiologies, including  Meibomian gland More Details dysfunction, computer vision-associated dry eye, and contact lens-induced dry eyes. There are multiple actions of omega-3 fatty acids that may have positive influence on the pathophysiology of post-LASIK dry eye, such as nerve regenerating potential, anti-inflammatory activity, and effect on goblet cell density[2].

Combinations of nerve growth factor, docosahexaenoic acid, and pigment epithelium-derived factor have been shown to improve nerve regeneration after injury to the cornea[3].

Optical coherence tomography (OCT) was first reported in 1991 as a noninvasive cross-sectional ocular imaging technology and today is the most promising noncontact high-resolution tomographic and biomicroscopic imaging device in ophthalmology[4].

The first anterior segment (AS) OCT was available in 1994. Its current use in cornea and refractive surgery includes phakic intraocular lens implantation, LASIK enhancement, and lamellar keratoplasty[5].

Ultra-high-resolution OCT has been used for evaluation of tear fluid dynamics, contact lens fitting, imaging of corneal structures, and to describe the characteristics of epithelium, stroma, and Descemet's membrane in corneal dystrophies and degenerations[6].

OCT imaging is based on measuring the delay of light (typically infrared) reflected from tissue structures. OCT employs low-coherence interferometry to compare the delay of tissue reflections against a reference reflection. To obtain an OCT image, the instrument scans a light beam laterally, creating a series of axial scans (A-scans), after which it combines these A-scans into a composite image. Each A-scan contains information on the strength of reflected signal as a function of depth[7].

In the vertical OCT scans, the existence, number, and height of the conjunctival folds and their coverage by tear film were detected; three parameters were usually measured: the tear meniscus height (TMH), tear meniscus depth (TMD), and tear meniscus area. In summary, OCT can be a valuable noninvasive and quick clinical tool for the evaluation of a tear film[8].

The aim of this work was to evaluate tear menisci parameters by AS-OCT in diagnosis of dry eye after LASIK procedure and evaluation of the role of oral omega-3 supplementation in the management of dry eye after LASIK.


  Patients and methods Top


This prospective study was performed on 50 participants who underwent LASIK procedure for evaluation of tear menisci parameters by AS-OCT. This study was carried out in Meet Ghamr, a highly qualified eye center (Meet Ghamr Eye Center), in the period between August 2018 and August 2019. Approval for performing the study was obtained from the ethical committee of Faculty of Medicine, Menofyia University. Consent from all patients was taken. These participants were further divided in two groups: the first group included 25 participants with supplementation of omega-3 fatty acids for 1 week preoperatively and 1 month postoperatively, and a second group included 25 patients without omega-3 supplement.

The mean age of the studied patients with omega-3 administration was 33.2 ± 10.49 years old, with a range from 19 to 45 years. Overall, 80% of the studied groups were female and 20% were male. However, in the control group, the age of the studied patient was 33.6 ± 12.29 years, with a range from 19 to 48 years. Approximately two-thirds of the studied group were female (60%) and 40% were male, with no statistically significant difference between both groups [Table 1].
Table 1: Demographic data of the studied omega group and control group (n=50)

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Inclusion criteria

All participants had a negative history and signs of previous or present systemic and ocular disorders. Their age was 19 years or greater and had stable refractive error for the last 1 year.

Exclusion criteria

All participants with any inflammatory pathology of the lid margin, tarsal conjunctiva, lacrimal drainage abnormalities, or any history of lacrimal gland pathology were excluded from the study.

All the following criteria were an indication to be excluded from study: presence of structural or functional lid anomalies; current use of systemic corticosteroid, immunosuppressive therapy, antidepressants, antihistamines, or anticoagulants; presence of autoimmune diseases, collagen vascular diseases, or diabetes mellitus; pregnant, nursing, or lactating women; patients having malabsorption syndromes; patients with allergy to fish oils; and patients with contact lens use, and if using, it was stopped at least 2 weeks before recruiting the patients for the study.

Fourier-domain OCT system (RTVue-100; Optovue Inc., Fremont, California, USA) with a cornea anterior module long adapter lens (1.96-mm scan depth and 6-mm scan width) was used in this study. The device worked at 830-nm wavelength and had a scan speed of 26 000 axial scans per second. The axial resolution of the system was 3 μm [Figure 1].
Figure 1: Optovue device: (a) patient view and (b) operator view.

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To obtain the images of tear film, cross-line scan mode was used, and the participant was asked to fixate at a peripheral target to maintain the perpendicularity of the OCT beam at the surface of the targeted tissue, which was essential for obtaining accurate values.

For the visualization of the lower tear meniscus, the scan axis was centered at about the middle of the lower eyelid. For the visualization of the upper tear meniscus, the scan axis was centered at about the middle of the upper eyelid. During the imaging of the right eye, the patients were instructed to position their heads in a 45° turn to the left.

Vertical images were recorded at the 6-o'clock position of the cornea to obtain the lower tear meniscus values and at 12-o'clock position of the cornea to obtain the upper tear meniscus values 3 s after each blink, which repeated three times, and a built-in caliper was used [Figure 2].
Figure 2: Cross-line (a) 6-o'clock position and (b) 12-o'clock position.

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TMH was determined as the length from the point where the meniscus intersected with the cornea superiorly to the eyelid inferiorly. TMD was determined as the length from the apex of the fornix to the surface of the tear meniscus perpendicular to TMH. The borders of the tear meniscus were marked with a caliper, and an integrated analysis software calculated TMH, TMD, and the area in mm2 [Figure 3].
Figure 3: The tear meniscus parameters: TMH, TMD, and TMA. TMA, tear meniscus area; TMD, tear meniscus depth; TMH, tear meniscus height.

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Postoperative follow-up

Re-evaluation of all parameters of upper and lower eye tear menisci was done by Fourier-domain OCT system after LASIK for all cases at first day, first week, and repeated at the end of first month for the evaluation of upper and lower tear menisci values [Figure 4]. The participants of the first group were instructed to use oral supplementation of omega-3 fatty acids for 1 month.
Figure 4: Postoperative follow-up and the evaluation of the tear meniscus parameters: TMH, TMD, and TMA. TMA, tear meniscus area; TMD, tear meniscus depth; TMH, tear meniscus height.

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Statistical analysis

The collected data were analyzed by computer using Statistical Package of Social Services, version 24 (IBM SPSS Statistics for Windows; IBM Corp. Armonk, New York, USA). Data were represented in tables. Paired t test and Mann–Whitney test for comparison between two groups and Freidman test for comparison within same group were used to assess the efficacy outcomes through pre/post-LASIK data. The results were considered statistically significant when the significant probability was less than 0.05 (P < 0.05). P value less than 0.001 was considered highly statistically significant, and P value more than or equal to 0.05 was considered statistically insignificant.


  Results Top


There was a significant improvement in the visual acuity in the studied group after LASIK. It increased from a preoperative value of 0.209 ± 0.160 to 0.831 ± 0.230 at 1 month after the procedure.

The current study was conducted to evaluate the upper and lower tear menisci in diagnosis of dry eye using AS-OCT before and after LASIK.

This shows that upper tear meniscus height (UTMH), upper tear meniscus depth (UTMD), and upper tear meniscus area (UTMA) were statistically higher in omega-3-treated group than the control group preoperatively and at 1 day, 1 week, and 1 month postoperatively.

Moreover, the lower tear meniscus height (LTMH), lower tear meniscus depth (LTMD), and lower tear meniscus area (LTMA) were statistically higher in omega-treated group than control group at 1 day, 1 week, and 1 month postoperatively, but there was no statistical difference between both groups preoperatively [Table 2].
Table 2: Upper and lower tear menisci parameters preoperatively and postoperatively among the studied omega-3 and control groups

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This current study showed that UTMH and UTMA were statistically lower than LTMH and LTMA preoperatively and 1 day, 1 week, and 1 month postoperatively among the studied patients.

In addition, UTMD was statistically lower than LTMD preoperatively and 1 month postoperatively among the studied patient, but there was no statistical difference between UTMD and LTMD at 1 day and 1 week postoperatively [Table 3].
Table 3: Upper and lower tear menisci parameters preoperatively and postoperatively among the studied group by anterior segment optical coherence tomography

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  Discussion Top


The present study was designed to evaluate tear meniscus after LASIK surgery by AS-OCT by measuring the upper and lower tear menisci height, depth, and area preoperatively and at 1 day, 1 week, and 1 month postoperatively.

Giannaccare et al.[9] found in their meta-analysis higher improvement of dry eye symptoms and breakup time after omega-3 FA supplementation compared with placebo. So, we compared the preoperative data to postoperative changes (after LASIK) of TMH and TMD after administration of omega-3 FA.

A total of 50 cases (20 male and 30 female) were included in this study. The right eye only was subjected to preoperative and post-LASIK measurements of TMH and TMD by OCT. The mean age was 33.6 ± 12.16 years.

We divided the study group into two groups: one group (25 cases) with administration of omega-3 fatty acid and another control group (25 cases) without administration of it. The OCT parameters between the two groups were evaluated and compared.

In the current study, we noticed that the mean postoperative UTMH in the omega-3 group was 153 ± 20.16 mm, being higher than that of the control group (122 ± 23.19 mm). Similarly, the mean postoperative (UTMD) in the omega-3 group was 135 ± 13.79 mm, although that of the control group was 101.2 ± 22.99 mm. The mean postoperative UTMA also was higher in the omega-3 group than of the control. The findings observed in the other parameters regarding the lower tear meniscus such as LTMH, LTMD, and LTMA mirror those of the upper tear meniscus.

These results are consistent with those of other studies. In a recent meta-analysis of randomized clinical trials by Giannaccare et al.[9], they found that omega-3 fatty acid supplementation significantly improved dry eye symptoms and signs in patients with dry eye disease. Liu and Ji[10] stated that omega-3 FA supplementation improves the TBUT and Schirmer values but not ocular discomfort symptoms compared with placebo. Conversely, according to Zhu et al.[11], FA supplementation failed to ameliorate DED signs while improving ocular discomfort symptoms.

In the current study, the upper tear meniscus parameters (UTMH, UTMD, and UTMA) were statistically lower than lower tear meniscus parameters preoperatively and 1 day, 1 week, and 1 month postoperatively among the studied group. This also in accordance with earlier observations by Hu et al.[12].

There are some limitations in this study. The major limitation of this study is the lack of a control group. The follow-up period of all patients was for only 1 month. This is a short period relative to the 3–9 months it takes for tear secretion. The use of artificial tears after LASIK was not restricted owing to ethical issues. Regarding omega-3, we could not identify any relationship between the efficacy and the dose and duration of treatment. The optimal omega-3 FA dose, omega-6/omega-3 ratio, and duration of treatment for achieving therapeutic benefit have yet to be defined.

Quality and quantity of tear fluid are considered valuable parameters for the diagnosis of dry eye disease. AS-OCT has been introduced to evaluate tear fluid. AS-OCT is considered a noninvasive approach to produce a tear meniscus image and a potential tool to diagnose dry eye after LASIK.

Acknowledgements

Authors' contribution: Mostafa K. Nassar contributed toward manuscript drafting and revision. Study design and data acquisition were the main task of the author. The author approved this version to be submitted.

Marwa A. Zaky contributed toward manuscript drafting and revision. Analysis and interpretation of data were the main task for the author. The author approved this version to be submitted.

Amany M.E. Mohamed contributed toward manuscript drafting and revision. Follow-up of the cases and interpretation of data was the main task for the author. The author approved this version to be submitted.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Bhargava R, Kumar P. Oral omega-3 fatty acid treatment for dry eye in contact lens wearers. Cornea 2015; 34:413–420.  Back to cited text no. 3
    
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Leung CKS, Cheung CYL, Weinreb RN, Qiu Q, Liu S, Li H, Lam DSC. Retinal nerve fiber layer imaging with spectral-domain optical coherence tomography: a variability and diagnostic performance study. Ophthalmology 116:2009; 1257–1263.  Back to cited text no. 5
    
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Leung CKS, Chiu V, Weinreb RN, Liu S, Ye C, Yu M, Lam DSC. Evaluation of retinal nerve fiber layer progression in glaucoma: a comparison between spectral-domain and time-domain optical coherence tomography. Ophthalmology 2011; 118:1558–1562.  Back to cited text no. 6
    
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Sridhar MS, Martin R. Anterior segment optical coherence tomography for evaluation of cornea and ocular surface. Indian J Ophthalmol. 2018;66:367-372. doi:10.4103/ijo.IJO_823_17.  Back to cited text no. 7
    
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Ibrahim OM, Dogru M, Kojima T, Matsumoto Y, Wakamatsu TH, Tsubota K, Fujishima H. OCT assessment of tear meniscus after punctal occlusion in dry eye disease. Optom Vis Sci 2012; 89:E770–E776.  Back to cited text no. 8
    
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Giannaccare G, Pellegrini M, Sebastiani S, Bernabei F, Roda M, Taroni L, Campos EC. Efficacy of omega-3 fatty acid supplementation for treatment of dry eye disease: a meta-analysis of randomized clinical trials. Cornea 2019; 38:565–573.  Back to cited text no. 9
    
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Liu A, Ji J. Omega-3 essential fatty acids therapy for dry eye syndrome: a meta-analysis of randomized controlled studies. Med Sci Monit 2014; 20:1583.  Back to cited text no. 10
    
11.
Zhu W, Wu Y, Li G, Wang J, Li X. Efficacy of polyunsaturated fatty acids for dry eye syndrome: a meta-analysis of randomized controlled trials. Nutr Rev 2014; 72:662–671.  Back to cited text no. 11
    
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Hu L, Xie W, Liu J, Zhou Y, Zhou Q, Yu Y, Lu F. Tear menisci and corneal subbasal nerve density in patients after laser in situ keratomileusis. Eye Contact Lens 2015; 41:51–57.  Back to cited text no. 12
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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