|Year : 2017 | Volume
| Issue : 4 | Page : 134-137
Light microscopic examination of the anterior chamber cells in uveitis
Eiman Abd El-Latif
Department of Ophthalmology, Faculty of Medicine, Alexandria University, Alexandria, Egypt
|Date of Submission||01-Jul-2017|
|Date of Acceptance||30-Jul-2017|
|Date of Web Publication||8-Mar-2018|
Eiman Abd El-Latif
5 Soliman Mahmoud Street, Cleopatra, Alexandria 32112
Source of Support: None, Conflict of Interest: None
Background Uveitis is a serious ocular condition with potentially blinding complications. It can be a sign of a large number of disorders with diverse etiologies, both infectious and noninfectious.
Methods A prospective study was done on patients who presented with uveitis and grade 4 anterior chamber cells. A 0.1 ml aqueous sample was withdrawn under aseptic conditions in the operation theatre. All samples were prepared and examined by the same pathologist.
Results Light microscopic examination of the aqueous sample from the 16 eyes with a hypopyon revealed predominant neutrophils. On the other hand, light microscopic examination of the aqueous sample from the 22 eyes without a hypopyon revealed predominant lymphocytes.
Discussion The convection currents of the aqueous can be regarded as a vertically oriented centrifuge. Some centrifugal force is exerted on the particles suspended in the aqueous humor, and examples of these particles are inflammatory cells in anterior uveitis.
Conclusion The predominant type of inflammatory cells is not the same in all cases of anterior uveitis.
Keywords: anterior chamber cells, uveitis
|How to cite this article:|
El-Latif EA. Light microscopic examination of the anterior chamber cells in uveitis. J Egypt Ophthalmol Soc 2017;110:134-7
| Introduction|| |
Uveitis is a serious ocular condition with potentially blinding complications. It can be a sign of a large number of disorders with diverse etiologies, both infectious and noninfectious. Moreover, it can be the first presentation of some systemic diseases, thereby adding to the challenge the ophthalmologist faces reaching the exact diagnosis.
Anterior uveitis is the most common form of uveitis. Active anterior uveitis is characterized by the presence of inflammatory cells in the anterior chamber (AC), and their number reflects disease severity. Hypopyon is a feature of intense inflammation in which cells settle in the inferior part of the AC and form a horizontal level. It has long been known that grade 4 AC cells are associated with development of a hypopyon in uveitis associated with certain diseases such as ankylosing spondylitis and Behçet’s disease, whereas a similar grade of cells is not known to be associated with a hypopyon in uveitis associated with diseases such as sarcoidosis and juvenile idiopathic arthritis for example .
The authors hypothesized that not all eyes with anterior uveitis and grade 4 AC cells tend to develop a hypopyon because the type of inflammatory cells in the AC might be different. The aim of this study was to test this hypothesis by performing light microscopic examination of samples from the aqueous humor of eyes with active anterior uveitis with grade 4 aqueous cells, some of them displaying a hypopyon, and others lacking a hypopyon, in an attempt to gain insight into the predominant type of cells in each of these categories.
| Methods|| |
This study was approved by the Alexandria University Faculty of Medicine Research Ethics Committee and followed the tenets of the Declaration of Helsinki.
A prospective study was conducted on patients who presented with uveitis and grade 4 AC cells to the Outpatient Clinic of the Ophthalmology Department of the Main University Hospital in Alexandria, Egypt, between April 2015 and May 2016. Patients, of any age and of either sex, who presented with uveitis showing grade 4 AC cells, with or without a hypopyon, were included. Another inclusion requisite was having a systemic disease, known to be associated with uveitis, diagnosed by the patient’s treating internist. The included patients had either Behçet’s disease or ankylosing spondylitis, confirmed by the treating rheumatologist, sarcoidosis confirmed by the treating pulmonologist, or juvenile idiopathic arthritis stated by the pediatric rheumatologist.
Eyes with a visibly hemorrhagic hypopyon were excluded from the study. Previous corticosteroid treatment whether topical, peribulbar, intraocular, or systemic during the preceding 3 months, as well as previous steroid-sparing immunosuppressive treatment during the preceding 6 months, and previous surgery, including intraocular injections, during the preceding 6 months were the other exclusion criteria.
A 0.1-ml aqueous sample was withdrawn under aseptic conditions in the operation theater from 22 eyes with anterior uveitis and grade 4+ cells, with a hypopyon, and another 16 eyes with the same grade of cells but without a hypopyon. All patients were examined and operated upon by a single surgeon (the author). In line with the method described by Hogan et al. , all samples were immediately mixed with an equal volume of fixative consisting with 1% glutaraldehyde and 1% formaldehyde. The samples were then delivered to the same laboratory, part of the same tertiary level of care university hospital, within 1 h of their withdrawal. In the laboratory, the fluid was subjected to centrifugation. Alcohol was then added to the sediment for fixation. The sediment was then stained with Leishman stain and examined under the light microscope using the oil-immersion lens that enables visualization of the cells with a 100-fold magnification. All samples were prepared and examined by the same pathologist.
Grade 4+ AC cells were defined as AC cells more than 50 in a 2-mm-long and 1-mm-wide slit beam with maximal light intensity and magnification. Evaluation was made before mydriasis as, even in normal eyes, cells and pigment clumps may develop after pupillary dilatation. A hypopyon was diagnosed clinically when the examiner could detect a horizontal level of inflammatory cells in the AC, either by direct illumination or by gonioscopy.
Data were analysed using the statistical package for the social sciences (version 20; SPSS Inc., Chicago, Illinois, USA).
| Results|| |
The current study included 38 eyes of 24 patients who presented with uveitis and grade 4 AC cells. The mean age of the patients was 32 years (range: 5–49 years). Eighteen patents were male and six patients were female. Fourteen patients had bilateral uveitis with grade 4 AC cells and 10 patients had unilateral condition (six right eyes and four left eyes).
Of the 14 patients with a bilateral condition, six patients had juvenile idiopathic arthritis, four patients had Behçet’s disease, and four patients had sarcoidosis. The 12 involved eyes of the six patients with juvenile idiopathic arhthritis showed no hypopyon, and neither did the eight involved eyes of the four patients with sarcoidosis. Seven eyes of the four patients with Behçet’s disease showed hypopyon and one eye did not. Of the 10 patients with unilateral uveitis, six patients had ankylosing spondylitis and four patients had Behçet’s disease. The six involved eyes of the six patients with ankylosing spondylitis showed hypopyon, as well as three of the four involved eyes of the four patients with Behçet’s disease ([Table 1]).
Light microscopic examination of the aqueous sample from the 16 eyes with a hypopyon revealed predominant neutrophils, representing more than 50% of the inflammatory cells detected per film (identified as a large cell with a segmented nucleus and a granular cytoplasm) in the 16 (100%) eyes, with two of these eyes (12.5%) showing a contribution of macrophages representing about 10% of the white blood cell population in the examined film.
On the other hand, light microscopic examination of the aqueous sample from the 22 eyes without a hypopyon revealed predominant lymphocytes, representing more than 50% of the inflammatory cells detected per film (identified with its round nucleus occupying most of the cell volume) in 21 (95.45%) eyes and one (4.55%) eye showed a pleomorphic inflammatory cell population composed of lymphocytes, neutrophils, macrophages, and eosinophils, in order of prevalence.
| Discussion|| |
Data regarding the risk factors for hypopyon and regarding its prognostic significance are limited. Nussenblatt  reported that the occurrence of hypopyon did not worsen the visual prognosis of patients with Behçet’s disease. However, the relationship between hypopyon and subsequent outcome in other forms of uveitis is not well understood.
Until 2010, the frequency of hypopyon had been described in two small-sized to moderate-sized series of patients with various types of uveitis. D’Alessandro et al.  retrospectively reviewed 155 cases of acute anterior uveitis and found 11 (7%) cases of hypopyon (duration of follow-up not reported), nine of which were associated with HLA-B27 . BenEzra et al.  reviewed 49 patients with Behçet’s disease, finding that 17 (35%) developed hypopyon over 6–10 years of follow-up. The incidence of hypopyon for other forms of uveitis is unclear.
In 2010, Zaidi et al.  retrospectively reviewed 4911 patients with uveitis. Of these patients, 41 (8.3/1000) cases of hypopyon were identified at the time of cohort entry. Of these, 2885 initially free of hypopyon were followed up over 9451 person-years, during which 81 (2.8%) developed hypopyon (8.57/1000 person-years). They reported that risk factors for incident hypopyon included Behçet’s disease [adjusted relative risk (RR)=5.30, 95% confidence interval (CI): 2.76–10.2], diagnosis of a spondyloarthropathy (adjusted RR=2.86, 95% CI: 1.48–5.52), and HLA-B27 positivity (adjusted RR=2.04, 95% CI: 1.17–3.56). Patients with both a spondyloarthropathy and HLA-B27 tended to have higher risk than either factor alone (crude RR=4.39, 95% CI: 2.26–8.51). Diagnosis of intermediate uveitis (+/− anterior uveitis) was associated with a lower risk of hypopyon (adjusted RR=0.35, 95% CI: 0.15–0.85). Hypopyon incidence tended to be lower among patients with sarcoidosis (crude RR=0.22, 95% CI: 0.06–0.90; adjusted RR=−0.28, 95% CI: 0.07–1.15).The cytology of the aqueous humor has been of interest to ophthalmologists for years. Amsler et al.  and Verrey , as well as von Sallman et al.  fixed aqueous humor cells on a glass slide, stained them and examined them using the light a microscope but were unable to find or provide insight into the causes of the different cases of uveitis. Most studies have found the lymphocyte to be the most abundant cell in endogenous endophthalmitis and the neutrophil to be the most abundant cell in hypopyon uveitis ,,.
To the best of the authors’ knowledge, fairly limited explanation is available in the literature as to why certain diseases tend to present with hypopyon significantly more than others. In addition, in order to better understand the risk and importance of hypopyon, here we suggest an explanation of the layering of the hypopyon leukocytes.
In Newtonian mechanics, the term centrifugal force is used to refer to an inertial force (also called a ‘fictitious’ force) directed away from the axis of rotation that appears to act on all objects when viewed in a rotating reference frame. The centrifugal force exerted on a particle is directly proportional to the mass of the particle (centrifugal force=mass of the particle×velocity2/radius of the path).
The convection currents of the aqueous can be regarded as a vertically oriented centrifuge. Some centrifugal force is exerted on the particles suspended in the aqueous humor, and examples of these particles are inflammatory cells in anterior uveitis. The predominant type of inflammatory cells is not the same in all cases of anterior uveitis. If the innate immune system is dominating the immune response in a case of anterior uveitis, the predominant inflammatory cell in the AC will be the neutrophil. On the other hand, if the specific immune system (cell-mediated immune response) is dominating the immune response in a case of anterior uveitis, the predominant inflammatory cell in the AC will be the lymphocyte.
Neutrophils are fairly uniform in size with an average radius of 6 μm. Lymphocytes, on the other hand, are smaller cells, with an average diameter of 3.5 μm. This difference in radius creates a difference in the mass of each of the two types of cells, as the specific gravity of the cell substance is not significantly different between both (mass=volume×specific gravity) (volume of a sphere=4.19×radius3). Hence, the centrifugal force exerted on the neutrophil is, on average, 5.1 times that exerted on a lymphocyte. The aqueous convection currents push the excess (high grade) of neutrophils to the angle recess, eventually accumulating in the inferior angle by means of gravity, to form a hypopyon. The smaller (<one-fifth) force exerted on lymphocytes does not seem to be enough to send the lymphocytes all the way along the radius of the path to the AC angle recess.
This explains the tendency of certain cases of anterior uveitis with a dense AC cellular reaction to form a hypopyon, and the lack of tendency of other cases of anterior uveitis with a similarly dense AC cellular reaction to form it.
Understanding this can have a useful clinical application. Determining whether the predominant AC reaction is innate, formed mainly of neutrophils, or specific, formed mainly of lymphocytes, helps the examining ophthalmologist shorten the list of differential diagnosis. Diseases known to excite an innate AC reaction include Behçet’s disease, HLA-B27 associated anterior uveitis, seronegative spondyloarthropathies, and acute bacterial endophthalmitis. Diseases known to excite a cell-mediated AC reaction include juvenile idiopathic arthritis, sarcoidosis, and Vogt Koyanagi disease.
Interestingly, a case of anterior uveitis that presents during the first attack with a dense AC reaction with a hypopyon, and during the recurrences with a similarly dense AC reaction without a hypopyon, is probably Herpes Zoster induced, a disease notorious for demonstrating the classic biphasic (double-humped) immune response, with an initial innate phase and later cell-mediated waves.
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