·Review Article·
Neutrophil-to-lymphocyte ratio in ocular diseases: a
systematic review
Bengi Ece Kurtul1, Pinar Altiaylik Ozer2
1Department of
Ophthalmology, Hatay Mustafa Kemal University Tayfur Ata Sökmen Faculty of
Medicine, Hatay 31040, Turkey
2Department of
Ophthalmology, Ufuk University Faculty of Medicine, Ankara 06830, Turkey
Correspondence
to: Bengi Ece Kurtul. Department of Ophthalmology, Hatay Mustafa Kemal
University Tayfur Ata Sökmen Faculty of Medicine, Hatay 31040, Turkey.
becekurtul@yahoo.com
Received:
Abstract
AIM: To summarize the results of studies investigating
neutrophil-to-lymphocyte ratio (NLR) and to identify the role of NLR in ocular
diseases.
METHODS: With the aim of identifying the studies related to
NLR, a search was conducted on http://www.ncbi.nlm.nih.gov/pubmed by utilizing
the key words “neutrophil lymphocyte ratio, ocular diseases, and eye diseases”
up to February 2018. All of the original articles were assessed according to
date of publications, countries, clinics and topics. Studies about ocular
inflammatory diseases were evaluated according to their qualifications, review
methods and results.
RESULTS: A total of 4473 publications, including original
research articles and reviews were screened. The number of publications was
shown a regular logarithmic increase over the years. The majority of studies
were performed by clinics in Turkey and many of these publications were
performed by oncology and cardiology clinics. A total of 75 publications were
identified to be about ocular diseases.
CONCLUSION: Elevated NLR as a cheap, reproducible, and readily
available marker could be used as a diagnostic and/or prognostic marker in
ocular diseases.
KEYWORDS: neutrophil-to-lymphocyte
ratio; ocular diseases; inflammation; publication
DOI:10.18240/ijo.2019.12.18
Citation: Kurtul
BE, Ozer PA. Neutrophil-to-lymphocyte ratio in ocular diseases: a systematic
review. thalmol 2019; 12(12):1951-1958
INTRODUCTION
Ocular
inflammatory and vascular diseases are one of the most common diseases
resulting in irreversible blindness worldwide. In the past decades, numerous
studies have highlighted that different inflammatory reactions play crucial
roles in various eye disorders, including neovascular age-related macular
degeneration (AMD), retinopathy of prematurity (ROP), and proliferative
vitreoretinopathy[1-3].
Neutrophil-to-lymphocyte ratio (NLR) is a novel and widely accepted
inflammatory marker which has been identified to be associated with the
severity and prognosis of many oncologic and cardiovascular diseases[4-9]. The predictive value of the NLR
has also been discussed with regard to ocular vascular and inflammatory
diseases such as diabetic retinopathy (DR), AMD, retinal vein occlusion (RVO),
glaucoma, and dry eye disease (DED)[10-14].
However, reviews regarding the role of NLR in these diseases are inadequate. In
this review, therefore, we aimed to present the recent scientific literature on
NLR, its usage areas and limitations in patients affected by ocular diseases.
MATERIALS AND METHODS
A systematic search of PubMed,
Embase.com, and Web of Science was made to elucidate all comparative studies
that compared the NLR value in several ocular diseases.
Search Strategy We examined PubMed, ScienceDirect,
ClinicalTrials.gov and Cochrane Library databases for articles up to February
2018, with no language restrictions. Key words used to describe studies were
“ocular” OR “eye” OR “disease” OR “inflammation” AND “lymphocyte” OR
“neutrophil” OR “neutrophil to lymphocyte ratio”. We adapted search phrases
based on diverse bibliographic databases and index terms. The references from
selected papers were also reached in this review process. Studies investigating
NLR and its potential role in the ocular diseases such as AMD, glaucoma,
retinal vascular diseases have been described in this review.
NEUTROPHIL-TO-LYMPHOCYTE RATIO &
OCULAR DISEASES
Studies of the predictive value of
the NLR in patients with ocular diseases are summarized in Table 1. Scheme
summarizing the role of NLR in ocular diseases is presented in Figure 1. As
shown in the Figure 1, the number of lymphocytes decreases when the
inflammation takes place in the eye. On the one hand inflammation induces
neutrophilia. On the other hand, physiologic stress induces lymphopenia. In
other words, the release of endogenous glucocorticoids in reply to
local/systemic disorders, including ocular disorders may play a significant
role in the production of the lymphopenia[13].
Table 1 Studies of the predictive
value of the NLR in patients with ocular disorders
|
Study |
Year |
Participants |
Cutoff |
Outcomes |
|
Chittawar et al[10] |
2017 |
Consecutive T2DM patients |
>2 |
NLR of 2.00
had sensitivity and specificity of 64.2% and 63% in predicting retinopathy. |
|
Dursun et al[12] |
2015 |
RVO vs healthy controls |
>1.89 |
The NLR
values were elevated in RVO patients than the control subjects. |
|
Ozgonul et
al[13] |
2016 |
POAG/OHT patients vs healthy controls |
>2.1 |
Patients with
POAG have increased NLR and PLR levels compared with controls. In addition,
there was a linear relation between PSD, a predictor of glaucomatous visual
field defects, and NLR. |
|
Sengul et al[25] |
2017 |
AMD patients vs healthy controls |
>2 |
The NLR and
PLR in neovascular AMD group was found to be significantly higher than
controls. NLR and PLR were conversely proportional to BCVA and directly
proportional to CMT. |
|
Erol et al[26] |
2017 |
Patients with CSCR vs
healthy controls |
>1.93 |
NLR and CRP
were higher in acute CSCR. NLR, CRP, and MPV were independent variables for
chronic CSCR. |
|
Hu et al[39] |
2017 |
Infants who were screened for ROP |
- |
LMR levels
were higher but NLR levels were lower in ROP group. Higher LMR is independently
associated with the development of ROP. |
|
Li et al[50] |
2017 |
PACG patients vs
healthy contros |
>1.854 |
Neutrophil
count, NLR, and WBC counts were higher in PACG. In multiple linear
regression, WBC, neutrophil, NLR, and LMR were found to be related with PACG. |
|
Kurtul et
al[54] |
2016 |
Patients with PEXS/with PXG vs
healthy controls |
>1.72 for PEX |
The NLR was
significantly higher in PEXS and PXG group than healthy controls. |
|
Ozgonul et
al[55] |
2017 |
Male patients with idiopathic
AAU vs male healthy controls |
>1.51 |
This study
demonstrated that patients with idiopathic AAU had increased NLR and PLR
levels compared with control subjects. There was also a correlation between
CRP and NLR (P=0.002, r=0.461). |
|
Gunes et al[66] |
2017 |
Patients with NAION vs
healthy controls |
>1.64 |
NLR
measurements were remarkably higher in patients with NAION than those with
healthy participants and were related with erythrocyte sedimentation rate.
Furthermore, the NLR was related with vision outcomes. |
|
Bisgaard et al[67] |
2017 |
Patients with MS and ON vs
healthy controls |
- |
The NLR was
higher in MS and ON than healthy controls. |
|
Hu et al[70] |
2014 |
Patients with pSS vs healthy
controls |
- |
RDW and NLR are significantly
correlated with disease activity in patients with pSS. |
|
Karaca et al[74] |
2014 |
Patients with keratoconus vs
healthy controls |
>2.24 |
NLR value was
higher in the progressive keratoconus group. There was also a linear
correlation between NLR and progression. |
NLR: Neutrophil-to-lymphocyte
ratio; RVO:
Retinal vein occlusion; POAG: Primary open angle glaucoma; OHT: Ocular
hypertension; PLR: Platelet
to lymphocyte ratio; BCVA: Best corrected
visual acuity; CMT: Central
macular thickness; CSCR: Central serous chorioretinopathy; CRP: C-reactive
protein; MPV: Mean platelet
volume; LMR:
Lymphocyte-to-monocyte ratio; WBC: White blood cell count; PEXS: Pseudoexfoliation
syndrome; PXG: Pseudoexfoliation
glaucoma; AAU: Acute anterior
uveitis; NAION: Non-arteritic
anterior ischemic optic neuropathy; MS: Multiple sclerosis; ON: Optic neuritis; pSS: Primary Sjögren’s syndrome.
Figure 1 Scheme summarizing the role
of neutrophil-to-lymphocyte ratio in ocular diseases.
Age-related Macular
Degeneration AMD is a multifactorial, progressive
disease and is the most common cause of
central vision loss in the individuals >50y, with the rate of 0.05%
before the age of 50 rising to 30% after 74 years of age[15-17]. The pathogenesis of AMD has not been fully
understood, although many possible factors such as oxidative stress,
atherosclerotic-like changes, and inflammatory processes have been proposed[18]. There is growing
proof to suggest a role for retinal pigment epithelial (RPE) cell destruction
and death, caused by diverse mechanisms including elevated inflammatory
response and oxidative stress in AMD producing photoreceptor death and vision
loss. The RPE cells exposed to oxidative stress can elicit inflammation. The
accumulation of lipids, mainly in the form of drusen, is related with a chronic
inflammation[19].
Studies in recent years appointed to
a pronounced role of inflammation in AMD pathogenesis. There is a large body of
evidence demonstrating the association of C-reactive protein (CRP) with
endothelial dysfunction, oxidative stress and reactive oxygen species (ROS)
production in AMD patients[20].
There are some studies presenting the association of the incidence of AMD with
CRP, tumor necrosis factor-α and oxidative stress[21-22].
Ilhan et al[23] concluded
elevated NLR levels in AMD patients than controls and demonstrated that those
higher NLR levels were linked with patients’ age and disease stage. NLR values
were 2.39, 2.79 and 1.7 among dry AMD, wet AMD, and controls, respectively. In
another study we investigated the link between AMD and NLR and found that NLR
levels in dry type and wet type AMD patients were higher than controls, at
1.65, 1.98 and 1.46, respectively[24]. Additionally, neovascular AMD patients had higher NLR
and platelet to lymphocyte ratio (PLR) levels than controls. Mean NLR values
were 2.52 and 1.92, and PLR values were 131.82 and 110.09 respectively[25]. In the lights of these studies, it
seems that the relation between elevated NLR and AMD may have stronger
consequence to the wet subtype of AMD and possibly related to angiogenesis-related
inflammatory mechanisms. It is clear that further studies are needed to explore this relationship in
terms of prognosis of the disease.
Central Serous
Chorioretinopathy Central serous chorioretinopathy
(CSCR) is defined as serous detachment of neurosensory retina and causes vision
threat. It commonly affects middle-aged male subjects. The accurate pathophysiologic mechanism remains
unknown[26].
However, studies on this subject suggest that CSCR is an inflammatory disorder.
Choroidal perfusion or vascular endothelial growth factor (VEGF) abnormalities
are present[27].
Numerous cytokines such as VEGF, IL-6, and IL-8 besides other proinflammatory
cytokines might also be elevated in CSCR patients[28]. In the study performed by Erol et
al[26],
they demonstrated elevated NLR in
patients with acute CSCR than those with chronic CSCR and controls. They supported
the idea that neutrophils play a main role in acute CSCR, while platelets are
involved in advancement to chronic CSCR. Although many previous studies have
found a significant connection between CSM and local proinflammatory markers
such as VEGF, IL-6, IL-8, studies investigating the relationship between CSCR
and systemic inflammatory markers such as NLR are sparse. So there is limited
information about NLR role on the pathogenesis of CSCR in the literature. We
therefore suggest that large-scale, prospective investigations are needed on
this issue.
Retinal Vascular Diseases
Diabetic retinopathy It has been highlighted that chronic
inflammation is crucial in both development and acceleration of microangiopathy
and macroangiopathy in patients with diabetes mellitus[29]. DR is a diabetes-induced
microangiopathy affecting the retinal vascular structures. The pathogenesis of
the disease includes inflammation, ischemia, and progressive RPE cell
degeneration. The most common cause of visual deterioration in diabetic
patients[30-31]. DR is a
progressive disorder that develops in phases, from mild nonproliferative DR to
moderate-severe nonproliferative DR and lastly to the final stage of
proliferative DR. In terms of pathogenesis of DR studies have shown that
inflammation plays a role[32-33]. In a previous
study, the systemic neutrophil count was found elevated and associated with the
presence and severity of DR, and investigators concluded that
neutrophil-mediated inflammation may play an important role in the pathogenesis
of DR[34].
Afterwards, Ulu et al[11]
explored the relationship between DR and inflammation by using NLR, which is an
established inflammatory marker being measured routinely in complete blood
count tests. In that study, when compared with controls, diabetes patients had
significantly elevated NLR values (P<0.001). Additionally, DR
patients had higher NLR levels compared to patients without DR (P<0.001).
Furthermore, NLR values were associated with the occurrence of DR (r=0.466,
P<0.001) and DR grades (r=0.630, P<0.001). In a similar
study, NLR was associated with retinopathy, as well as nephropathy and coronary
artery disease, in Indians with type-2 diabetes[10]. Taken together, it seems that
the NLR is associated with both the presence of DR and the degree of DR. We can
speculate on the basis of the studies data mentioned above that there is a
strong relationship between DR and systemic chronic inflammation.
Retinal vein occlusion The ethiopathogenetic mechanism of
RVO is not fully elucidated, but, RVO is known as a disease that goes with
thrombotic and inflammatory processes. In a previous study carried out by
Dursun et al[12],
the association between NLR and the development of RVO was assessed. The NLR
values of the patients (n=40) and the control group (n=40) were
compared. The NLR values were found to be elevated in RVO patients than the
controls (3.0±2.7 vs 1.5±0.3, P<0.001). In the receiver
operating characteristics (ROC) analysis, to predict RVO, the cutoff value for
NLR was found as 1.89, with 72.5% sensitivity and 100% specificity. According
to study results, they concluded that higher NLR was associated with the
development of RVO. Although it cannot be said accurately according to only the
results of this study, it is understood that inflammatory processes as well as
thrombotic pathways may take part in the etiopathogenesis of RVO.
Retinopathy of prematurity ROP is leading cause of blindness in
premature babies worldwide. The disease affects the immature retinal vascular
system and thus occurs in premature infants with an partly vascularized retina.
Angiogenic factors, cytokines, and oxidative and growth factors play role in
ROP processes[35].
Inflammation has also been implicated in ROP pathogenesis beyond immaturity[2,36-37]. Given the role of inflammatory processes in ROP
development, in the previous study, we evaluated the relationship between serum
NLR and development of ROP. We found higher NLR values in the ROP group
relative to non-ROP group (P=0.02). The lymphocyte count was
significantly lower in the ROP group compared to the non-ROP group (P=0.001).
But, in multivariate analysis, only lymphocyte count detected independent
predictor of ROP [odds ratio (OR) 0.599; 95% confidence interval (CI),
0.430-0.836; P=0.003][38].
In addition to our study, in a
recently published study, Hu et al[39] aimed to evaluate the
associations between development of ROP and serum lymphocyte-to-monocyte ratio
(LMR), NLR, and PLR. The LMR levels were significantly higher and NLR levels
were significantly lower in ROP group than controls. Logistic regression analysis
suggested that not NLR but LMR was an independent risk factor for ROP. In the
light of the results of these two studies, we can say that the diagnostic and
prognostic role of NLR in patients with ROP remain controversial. A possible
reason for this discrepancy is that the size of the sample in these studies is
relatively small. Additionally, subject heterogeneity and accompanying
comorbidities may also account for this discrepancy. Despite all of these
limitations, we can conclude that there is no significant relationship between
NLR and ROP yet. Perhaps the mechanisms those are more dominant than
inflammation may be involved in ROP development.
Glaucoma Glaucoma is a neurodegenerative
disease that leads to progressive optic disc atrophy and visual field defects,
and it is frequently linked to an elevated intraocular pressure (IOP). Elevated
IOP is a risk factor for disease progression that can give rise to progressive
irreversible blindness[40].
Progressive degeneration of retinal ganglion cells and axons is the main cause
of glaucomatous visual loss[41-42]. This is
particularly so with a rapidly aging worldwide and the relatively high
incidence of glaucoma being observed among the elderly[43-44].
Primary angle closure glaucoma
(PACG) is an important subgroup of glaucoma. Increasing evidences are thought
that inflammatory mechanisms may have a role in the pathophysiology of glaucoma[45-48]. In patients with PACG,
circulating leucocyte and platelet counts will increase. As mentioned earlier,
the NLR, PLR and LMR investigated as predictors of adverse events in various
cancer types and cardiovascular diseases. However, to date there are only four
papers which showed that NLR and PLR may be helpful as biomarkers in patients
with normal-tension glaucoma[49],
primary open angle glaucoma (POAG)[13,50],
and pseudoexfoliation glaucoma (PXG)[51]. These studies provide significant information that
there is a probable role for inflammation as an initiating or progressing factor
in PACG patients.
When it comes to the POAG, Ozgonul et
al[13]
assessed the NLR and PLR values in patients with POAG and compared the NLR and
PLR results of patients with POAG and ocular hypertension, and healthy
controls. They found elevated NLR (P=0.003) and PLR (P=0.049)
levels in POAG patients. Thus we suggest that these parameters may be useful in
patients with POAG.
Pseudoexfoliation syndrome Pseudoexfoliation syndrome (PEXS) is
an age-related, systemic, and multifactorial disease. The pathogenesis of PEXS
consists of genetic and nongenetic causes, such as age, race, ultraviolet
beams, autoimmune disorders, trauma, infections, inflammation, and oxidative
stress[13,52-53]. Inflammatory biomarkers may
have a key role in clinical practice for these patients. In this context, we
previously investigated the relationship between serum NLR and PEXS[54]. We divided
participants into three groups: group 1: 55 patients with PEXS, group 2: 19
patients with PXG, and group 3: 48 control subjects. The NLR was considerably
elevated in group 1 and 2 than the group 3 (P<0.001). In ROC
analysis, the area under the curve for NLR for predicting PEXS was 0.776, and
NLR of >1.72 with a sensitivity of 77% and specificity of 71%. In a
consequence, we concluded that elevated NLR is significantly associated with
PEXS and this parker can provide useful information for risk evaluation in
these population.
In another study, Ozgonul et al[51] found a
substantial difference in favor of NLR and PLR levels between PEXS and control
groups (P=0.012) and PXG and control groups (P=0.003 and P=0.024,
respectively). These 2 studies show that there is a significant positive
correlation between inflammation and PXG development. However, it is necessary
to investigate whether there is a relationship between NLR and the course and
prognosis of the disease or not.
Uveitis The term “uveitis” determines all
inflammatory disorders of intraocular structures. The link among uveitis and
inflammatory processes are being investigated for ages. Uveitis is a
vision-threatening disease with intraocular inflammation that originating from
different causes. And it is one of the leading causes of functional loss of
vision and blindness at Western countries[55]. The categorization of uveitis,
may be derived from anatomical involvement or aetiology of the intraocular
inflammation. Anatomically the disease is categorized as anterior,
intermediate, posterior, and panuveitis. With regard to intraocular
inflammation, uveitis can also be classified as an aetiological, such as,
infections, autoimmune/immunity-mediated systemic disorders, traumatic,
drug-induced and lens-induced uveitis. The most frequent uveitis type is acute
anterior uveitis (AAU), which is related to intraocular inflammation
influencing the anterior part of the eye. CRP is a dependable indicator of
inflammatory disorders and prior published studies demonstrated that elevated
serum CRP values were detected in patients with uveitis[56-57]. Although documents from the ophthalmology centers associated
with NLR and PLR have a tendency to increase and they have rose to importance
as a reliable tool of several ophthalmic disorders, studies searching the
clinical significance of these tools, as indicator of idiopathic AAU patients
are inadequate.
In a previous published study,
investigators assessed the levels of the NLR and the PLR in patients with
idiopathic AAU and compared with healthy controls[55]. They showed a substantial
difference in NLR between idiopathic AAU and control groups. Moreover,
correlation analysis showed a linear association between CRP and NLR (P=0.002,
r=0.461). According to ROC analysis, the area under the curve for NLR
(cut-off value: 1.51) to discriminate patients and controls was found to be
0.689, with a sensitivity of 77.8% and a specificity of 55.6%. Therefore, the
predictive power of NLR was better than PLR. Finally, in a study was compared
the value of hematological parameters, NLR, PLR, and mean platelet volume
(MPV), as reflectors of anterior uveal segment involvement in Behcet’s disease
(BD)[58].
That study showed that all MPV, PLR, and NLR levels of patients with anterior
uveitis were considerably higher than other patients and healthy subjects. The
area under the curves for NLR was 0.725, P<0.001 for PLR was 0.600, P=0.012,
and for MPV was 0.358, P<0.001. In consideration of these findings,
the authors recommended that MPV, PLR, and NLR are all useful for evaluation of
anterior uveal segment involvement in BD. But, the NLR is more sensibly
compared with the PLR and MPV in predicting the disease.
Ischemic Optic Neuropathy Non-arteritic anterior ischemic
optic neuropathy (NAION) can cause loss of vision in middle age and elderly
population. The pathogenesis of this situation is not elucidated, but it is
believed to be a multifactorial disorder where different combinations of some
local and systemic risk factors play a role in the development of NAION[59]. Acute ischemia
of the optic nerve head is commonly accepted in the pathogenesis of NAION[60-61]. Also, early inflammation
components were determined in clinical NAION[62-63]. NAION initially causes early cytokine mediated
changes[64],
and then progressive activation of inflammatory cells are taken place[62]. Bernstein et
al[63]
tested optic nerve changes in primate NAION models where capillary thrombosis
was triggered by laser light and demonstrated that early post-infarct
happenings showed inflammatory response and recommended that modulation of
inflammation might be helpful in the management of NAION. In a case-control
study, Polat et al[65]
evaluated the utility of NLR in NAION patients. They found elevated NLR
levels in patients with NAION than control subjects. Moreover it was inversely
association regarding best corrected visual acuity at the initial and third
month exam between groups. In ROC curve analysis, cut-off value of NLR for
predicting NAION was 1.94, with the 60% sensitivity and 63% specificity. As the
sensitivity and specificity of the cut-off value of NLR was determined somewhat
lower in this study, we recommended that the cutoff value may not be beneficial
for NAION patients in daily practice. Similarly, Gunes et al[66] found
considerably elevated NLR levels in NAION patients than in healthy subjects,
but in their study the cut-off value for NLR was 1.64, with 85% sensitivity and
41% specificity. Also, the NLR value was correlated with visual results. In
patients with higher NLR, the initial and final visual acuities were
significantly poor than in patients with lower NLR. Lastly, in a retrospective
study, it was shown that NLR was higher in multiple sclerosis and optic
neuritis patients compared to healthy controls[67]. In consideration of these
studies above mentioned, we can say that NLR may be helpful in clinical
performances to predict a NAION patient’s visual outcomes. But we should
keep in mind that certain diseases may affect the neutrophil and/or lymphocyte
count (and therefore NLR). So, there is also a need to compare the NLR with
other markers of inflammation, such as CRP and IL-6.
Dry Eye Disease DED is a chronic ophthalmic
situation that affects roughly 10%-30% of the people older than 50 years old[68]. Chronic ocular
surface inflammation is a key component of DED and the disease leads to ocular
pain, discomfort, and visual symptoms. Although the substantial role of
inflammation in its pathogenesis is widely accepted, the precise mechanism of
the inflammatory response is not elucidated yet. In the tear fluid increased
levels of several proinflammatory mediators have been demonstrated by various
studies. Because anti-inflammatory medications alleviate signs and symptoms of
DED, the idea of inflammatory pathways in the pathophysiology of the disease has been supported[69].
In addition to these studies, Hu et
al[70]
investigated the clinical significance of red blood cell distribution width
(RDW) and NLR in primary Sjögren’s syndrome (pSS) patients. They suggested that
RDW and NLR may
be useful tools to guess pSS disease activity. Sekeryapan et al[71] assessed the role
of NLR in patients with DED as an indicator of inflammation. The NLR values
were higher in non-Sjögren dry eye patients compared with control subjects.
Consequently, they suggested that non-Sjögren DED may be related with
inflammation and the NLR levels increases in inflammatory ophthalmic disorders.
Recently, Celik[14]
calculated the NLR and PLR values in patients with DED and controls, he found a
statistically significant difference in the NLR and PLR values between groups (P=0.032
and P=0.026, respectively). Consequently, both PLR and NLR may be
helpful to foresee the inflammatory response in DED. These results suggest that
non-Sjögren DED may be associated with systemic inflammation besides local
inflammation. In the light of these studies, we have thought that further
studies with large-scale are needed to confirm these outcomes and reveal the
significance of NLR values in grading DED and monitoring therapy.
Keratoconus Keratoconus is an ectatic corneal
disorder and leads to astigmatism, myopia, and vision disorder[72]. Even though
keratoconus is known as a noninflammatory disorder, current reports have
demonstrated that proinflammatory factors may also play a role in the
pathogenesis of the disease[73-74]. The relation
between NLR and keratoconus has been investigated, and the NLR values were
higher in progressive keratoconus patients compared to nonprogressive group and
controls[74].
There was also a positive correlation between NLR and disease progression (P<0.05).
In the ROC curve analysis, an NLR≥2.24 cutoff value predicted the disease
progression. However, in a large population size study, the investigators found
no significant relationship between CRP and keratoconus[75]. Like non-Sjögren DED,
keratoconus is a local inflammatory disease of the eye, so local inflammatory ocular
conditions may be thought to increase the serum NLR values.
CONCLUSION
In this review, we have presented a
useful summary of the evidence available in literature about the association of
NLR with ocular diseases. In conclusion, we think that several eye diseases may
also be associated with systemic inflammation in addition to local
inflammation. Thus, it seems that the NLR is easily performed, reproducible,
cheap, and reliable laboratory biomarkers to test the inflammatory response in
ocular inflammatory diseases. These NLR studies may also give us important
information to find some new potential clues or mechanisms for several eye
diseases. Nevertheless, these observations explain the need to improve further
prospective studies.
ACKNOWLEDGEMENTS
Conflicts of Interest: Kurtul BE, None; Ozer PA,
None.
REFERENCES