Effect of Chalazion on Corneal Astigmatism
Divya N 1, Madhumitha.P. S 2, Panimalar A Veeramani 3,Bindu Bhaskaran Associate professor 1, Junior Resident 2, Associate Professor 3, Senior Resident Department of ophthalmology,Saveetha medical college and hospital,Chennai,Tamil Nadu,
India.
Corresponding author: Panimalar A Veeramani [email protected]
ABSTRACT
A common eyelid disease chalazion causes eye morbidity due to inflammation and cosmetic disfigurement. Important factors in corneal refractive surgery, intraocular lens power calculations for cataract surgery and visual acuity assessments are corneal topographic changes.
For better outcome of ocular surgery corneal astigmatism should be corrected earlier. The aim of this study is to evaluate changes in corneal astigmatism according to chalazion size and location.
Keywords:-Chalazia, Astigmatism, Wavefront, Corneal topography
Introduction
A chalazion is a meibomian gland lipogranulomatous condition which presents as swelling on the eyelids [1]. It is a condition that causes eye morbidity due to inflammation and cosmetic disfigurement [2]. This condition is associated with chronic blepharitis, seborrheic dermatitis [1]. Chalazia treatment includes such as warm compression and topical antibiotic eye drops or ointment and surgical incision and curettage, with or without triamcinolone intralesional injection [3] If left untreated amblyopia may develop in children with corneal astigmatism in rare cases [7]. It has been reported that pressure on the upper eyelid by chalazion induces hyperopia and astigmatism.7 Chalazia can increase higher-order aberrations (HOAs), as measured by the Hartmann–Shack aberrometer;
Literature Review
This study aims in establishing a strong relationship between chalazion and astigmatism and that a simple procedure could be done to achieve best corrected visual acuity.
Table 1 Demographic data of subjects Control 70
Chalazion group 44
Site
Upper eyelid 22 Lower eyelid 16 Both eyelid 6
Location
Nasal 10 Middle 25 Temporal 4 Whole. 3 Size Small 14
Lpp
Medium 17 Large 11
Table 2 Corneal topographic data between chalazion and control group Total Chalazion group Control group p-value
N (eyes) 114 44. 70
Gender 52:62. 19:25 33:37
Age (year). 41.59 ± 14.08 39.57 ± 13.83 42.86 ± 14.18 0.226
CCT (μm) 547.25 ± 39.90 546.91 ± 43.64 547.46 ± 37.69 0.943 ARK (D 42.96 ± 1.86 42.84 ± 2.08 43.03 ± 1.72 0.603
Astigmatism by ARK (D) -0.85 ± 0.99 −0.94 ± 1.44 −0.79 ± 0.58 0.546
Axis by ARK (°) 104.23 ± 63.36 108.63 ± 60.74 101.48 ± 65.26 0.579
SimK (D) 42.76 ± 3.49 42.43 ± 2.28 42.96 ± 4.08 0.434 Associate
Astigmatism by simK (D) 1.31 ± 0.96 1.53 ± 1.16 1.17 ± 0.78 0.074
Axis by simK (°) 84.74 ± 35.24b. 85.16 ± 28.23 84.47 ± 39.20 0.914
Mean K of posterior surface −6.28 ± 0.27 −6.25 ± 0.24 −6.29 ± 0.28 0.514 Astigmatism of posterior surface −0.44 ± 0.29−0.46 ± 0.26 −0.43 ± 0.32 0.691 Total RMS (μm) 1.81 ± 0.80 1.97 ± 1.05 1.71 ± 0.59 0.127 2nd order aberration (μm) 1.55 ± 0.70 1.68 ± 0.87 1.48 ± 0.55 0.184
Oblique astigmatism (Z−22; μm)0.04 ± 0.49 0.18 ± 0.52 −0.05 ± 0.45 0.013*
Defocus (Z02; μm) −0.85 ± 0.50 −0.83 ± 0.53 −0.87 ± 0.49 0.693
Vertical astigmatism (Z22; μm)−0.74 ± 1.06 −0.98 ± 1.16 −0.59 ± 0.98 0.057
3rd order aberration (μm) 0.67 ± 0.42 0.71 ± 0.53 0.64 ± 0.34 0.398
Vertical trefoil (Z−33; μm)−0.18 ± 0.40 −0.24 ± 0.44 −0.14 ± 0.37 0.216 Vertical Coma (Z−31; μm) 0.34 ± 3.01 0.13 ± 0.37 0.48 ± 3.84 0.555 Horizontal coma (Z13; μm)−0.04 ± 0.31 −0.04 ± 0.29 −0.04 ± 0.33 0.961 Oblique trefoil (Z33; μm) −0.02 ± 0.44 −0.06 ± 0.55 −0.01 ± 0.35 0.378 4th order aberration (μm) 0.40 ± 0.30 0.40 ± 0.30 0.40 ± 0.30 0.921
Oblique quadrefoil (Z−44; μm)0.01 ± 0.09 0.02 ± 0.10 0.00 ± 0.07 0.293 Oblique secondary astigmatism 0.01 ± 0.13 −0.01 ± 0.14 0.01 ± 0.11 0.333
Primary spherical (Z04; μm)0.17 ± 0.30 0.17 ± 0.32 0.16 ± 0.30 0.922 Vetical secondary astigmatism0.07 ± 0.18 0.05 ± 0.19 0.08 ± 0.18 0.447
Vertical quadrefoil (Z44; μm)−0.11 ± 0.23 −0.11 ± 0.22 −0.12 ± 0.24 0.888
Table 3 Corneal topographic data according to site of chalazion
Control Upper eyelid Lower eyelid Both eyelids p-value
N 70 22 16. 6
Gender (M:F) 33:37 10:12. 3:13 6:0
Age (year)42.86 ± 14.18 41.27 ± 12.41 38.63 ± 16.74 35.83 ± 11.16 0.519
CCT (μm) 547.46 ± 37.695583.27 ± 42.50 528.25 ± 45.57 555.00 ± 28.33 0.136
Average keratometry. 43.03 ± 1.72 43.38 ± 1.69 42.18 ± 2.58 42.82 ± 1.44 0.269
Astigmatism by ARK (D) -0.79 ± 0.58 −1.12 ± 1.93 −0.88 ± 0.85 −0.50 ± 0.45 0.490
Axis by ARK (°). 101.48 ± 65.26 118.16 ± 67.99 102.50 ± 53.94 92.00
± 57.73 0.750
SimK (D) 42.96 ± 4.08 43.11 ± 1.69 41.51 ± 2.99 42.42 ± 1.21 0.470
Astigmatism by simK 1.17 ± 0.78 2.01 ± 1.27 0.98 ± 0.59 1.23 ± 1.26 0.001*
Axis by simK (°) 84.47 ± 39.20 83.05 ± 25.31 88.31 ± 27.04 84.50 ± 43.78 0.470
Mean K of posterior surface−6.29 ± 0.28 −6.29 ± 0.29 −6.24 ± 0.15 −6.16 ± 0.25 0.653 Astigmatism of posterior surface−0.43 ± 0.32−0.53 ± 0.32 −0.36 ± 0.13 −0.42 ± 0.16 0.336 Total RMS (μm). 1.71 ± 0.59 2.35 ± 1.13 1.46 ± 0.39 1.96 ± 1.47 0.002*
2nd order aberration (μm) 1.48 ± 0.55 2.11 ± 1.04 1.23 ± 0.31 1.24 ± 0.20
<0.001*
Oblique astigmatism −0.05 ± 0.45 0.33 ± 0.57 −0.03 ± 0.40 0.21 ± 0.43 0.009*
Defocus (Z02; μm) −0.87 ± 0.49 −0.79 ± 0.72 −0.82 ± 0.25 −0.99 ± 0.10 0.820 Vertical astigmatism −0.59 ± 0.98 −1.55 ± 1.28 −0.48 ± 0.69 −0.25 ± 0.62 0.001*
3rd order aberration (μm)0.64 ± 0.34 0.85 ± 0.68 0.55 ± 0.17 0.62 ± 0.43 0.129
Vertical trefoil (Z−33; μm)−0.14 ± 0.37 −0.28 ± 0.54 −0.16 ± 0.21 −0.31 ± 0.50 0.470 Vertical Coma (Z−31; μm) 0.48 ± 3.84 0.23 ± 0.41 −0.02 ± 0.31 0.18 ± 0.30 0.939 Horizontal coma (Z13; μm)−0.04 ± 0.33 −0.025 ± 0.29 −0.13 ± 0.31 0.13 ± 0.15 0.398 Oblique trefoil (Z33; μm) −0.01 ± 0.35 −0.16 ± 0.72 −0.01 ± 0.28 0.14 ± 0.30 0.332 4th order aberration (μm) 0.40 ± 0.30 0.44 ± 0.21 0.39 ± 0.40 0.30 ± 0.27 0.802
Oblique quadrefoil 0.00 ± 0.07 0.03 ± 0.14 0.02 ± 0.05 −0.02 ± 0.03 0.422
Oblique secondary astigmatism0.01 ± 0.11 −0.02 ± 0.16 −0.00 ± 0.11 0.03 ± 0.15 0.618
Primary spherical (Z04; μm)0.16 ± 0.30 0.10 ± 0.23 0.29 ± 0.43 0.11 ± 0.09 0.243
Vetical secondary astigmatism 0.08 ± 0.18 0.10 ± 0.21 −0.01 ± 0.16 0.02 ± 0.06 0.230 Vertical quadrefoil −0.12 ± 0.24 −0.13 ± 0.25 −0.07 ± 0.11 −0.15 ± 0.33 0.876
SimK simulated keratometry, ARK autorefractokeratometry, RMS root mean square, D diopter;
Results were presented as mean ± standard deviation.*Statistically significant by ANOVA
Table 4 topographic changes according to chalazion location
Control Nasal Middle Temporal Whole p-
value
n 70 10 25 4 3
Gender (M:F) 33:37 5:5 9:16 2:2 2:1
Age (year) 42.86 ±
14.18
42.20 ± 16.29
38.12 ± 13.66
43.75 ± 14.48
45.67 ± 4.51 0.679
CCT (μm) 547.46 ±
37.69
550.50 ± 19.60
542.16 ± 50.65
542.25 ± 32.40
552.33 ± 14.05
0.952
Average keratometry by ARK (D)
43.03 ± 1.72 42.44 ± 1.71 42.83 ± 2.35 44.79 ± 1.51 42.51 ± 0.88 0.411
Astigmatism by ARK (D) -0.79 ± 0.58 −0.93 ± 1.01 −0.79 ± 58.50
−2.58 ± 3.19 −0.75 ± 0.35 0.046*
Axis by ARK (°) 101.48 ± 65.26
108.89 ± 61.53
115.00 ± 58.50
126.67 ± 70.77
105.00 ± 49.50
0.851
SimK (D) 42.96 ± 4.08 41.96 ± 1.91 42.33 ± 2.59 43.47 ± 1.62 43.86 ± 2.15 0.823 Astigmatism by simK (D) 1.17 ± 0.78 1.16 ± 1.14 1.54 ± 1.13 1.61 ± 1.79 2.30 ± 0.56 0.143 Axis by simK (°) 84.47 ±
39.20
80.00 ± 33.72
82.92 ± 27.77
103.00 ± 29.06
92.00 ± 22.54
0.843
Mean K of posterior surface (D)
−6.29 ± 0.28 −6.19 ± 0.20 −6.24 ± 0.24 −6.40 ± 0.34 −6.42 ± 0.37 0.543
Astigmatism of posterior surface (D)
−0.43 ± 0.32 −0.43 ± 0.13 −0.45 ± 0.32 −0.46 ± 0.19 −0.58 ± 0.13 0.942
Total RMS (μm) 1.71 ± 0.59 1.64 ± 0.76 2.03 ± 1.14 2.09 ± 1.48 2.37 ± 1.05 0.243 2nd order aberration (μm) 1.48 ± 0.55 1.35 ± 0.78 1.69 ± 0.82 1.90 ± 1.53 2.14 ± 0.93 0.219 Oblique astigmatism (Z−22
; μm)
−0.05 ± 0.45 0.06 ± 0.48 0.17 ± 0.49 0.44 ± 0.82 0.58 ± 0.47 0.033*
Defocus (Z02; μm) −0.87 ± 0.49 −0.75 ± 0.34 −0.94 ± 0.15 −1.09 ± 0.06 0.22 ± 1.80 0.003*
Vertical astigmatism (Z22; μm)
−0.59 ± 0.98 −0.56 ± 1.11 −1.00 ± 1.19 −1.18 ± 1.68 −1.51 ± 0.54 0.269
3rd order aberration (μm) 0.64 ± 0.34 0.65 ± 0.36 0.75 ± 0.66 0.67 ± 0.19 0.71 ± 0.30 0.877 Vertical trefoil (Z−33; μm) −0.14 ± 0.37 −0.27 ± 0.40 −0.31 ± 0.47 −0.01 ± 0.24 0.11 ± 0.51 0.212 Vertical Coma (Z−31; μm) 0.48 ± 3.84 0.18 ± 0.24 0.16 ± 0.41 −0.12 ± 0.39 0.10 ± 0.46 0.986 Horizontal coma (Z13; μm) −0.04 ± 0.33 −0.07 ± 0.26 −0.05 ± 0.28 0.15 ± 0.47 0.00 ± 0.24 0.820 Oblique trefoil (Z33; μm) −0.01 ± 0.35 −0.12 ± 0.42 −0.13 ± 0.64 0.29 ± 0.19 0.10 ± 0.24 0.349 4th order aberration (μm) 0.40 ± 0.30 0.43 ± 0.20 0.38 ± 0.34 0.36 ± 0.07 0.56 ± 0.50 0.885 Oblique quadrefoil (Z−44;
μm)
0.00 ± 0.07 0.03 ± 0.14 0.03 ± 0.10 0.01 ± 0.01 −0.05 ± 0.06 0.380
Oblique secondary astigmatism (Z−42; μm)
0.01 ± 0.11 −0.03 ± 0.12 −0.02 ± 0.12 0.15 ± 0.12 −0.14 ± 0.16 0.015*
Primary spherical (Z04; μm)
0.16 ± 0.30 −0.03 ± 0.12 −0.02 ± 0.12 0.20 ± 0.14 −0.11 ± 0.50 0.590
Vetical secondary astigmatism (Z24; μm)
0.08 ± 0.18 0.17 ± 0.26 0.20 ± 0.34 −0.03 ± 0.15 0.12 ± 0.41 0.754
Vertical quadrefoil (Z44; μm)
−0.12 ± 0.24 0.03 ± 0.25 0.05 ± 0.12 0.01 ± 0.20 −0.18 ± 0.39 0.710
Table 5 Corneal topographic changes according to chalazion size Control. Small Medium Large p-value
N 70 14. 17 11
Gender (M:F) 33:37 5:9 6:11. 7:4
Age (year) 42.86 ± 14.18 43.64 ± 19.08 38.47 ± 10.72 38.36 ± 10.00 0.543
CCT (μm) 547.46 ± 37.69 539.29 ± 27.84 555.29 ± 34.43 535.91 ± 60.86 0.526
Average keratometry by ARK 43.03 ± 1.72 43.66 ± 1.01 42.71 ± 2.11 42.09 ± 2.96 0.224
Astigmatism by ARK (D) -0.79 ± 0.58 −0.85 ± 0.88 −0.89 ± 1.67 −1.20 ± 1.82 0.688
Axis by ARK (°) 101.48 ± 65.26 108.33 ± 50.24 113.75 ± 66.37 121.00
± 55.42 0.714
SimK (D) 42.96 ± 4.08 43.07 ± 1.11 42.23 ± 2.30 42.05 ± 3.41 0.767
Astigmatism by simK (D). 1.17 ± 0.78 1.05 ± 0.67 1.69 ± 1.43 1.82 ± 1.13 0.037*
Axis by simK (°) 84.47 ± 39.20 89.93 ± 39.47 80.76 ± 26.52 84.45 ± 13.91 0.917
Mean K of posterior surface (D) −6.29 ± 0.28 −6.23 ± 0.19 −6.25 ± 0.27 −6.30 ± 0.29 0.858
Astigmatism of posterior surface −0.43 ± 0.32 −0.34 ± 0.12 −0.54 ± 0.36 −0.48 ± 0.14 0.322
Total RMS (μm) 1.71 ± 0.59 1.77 ± 0.96 1.90 ± 1.05 2.33 ± 1.24 0.113
2nd order aberration (μm) 1.48 ± 0.55 1.34 ± 0.37 1.68 ± 1.04 2.06 ± 1.00 0.036*
Oblique astigmatism (Z−22; μm) −0.05 ± 0.45 0.09 ± 0.48 0.09 ± 0.50 0.49 ± 0.55 0.006*
Defocus (Z02; μm) −0.87 ± 0.49 −0.89 ± 0.31 −0.94 ± 0.15 −0.56 ± 0.96 0.222
Vertical astigmatism (Z22; μm) −0.59 ± 0.98 −0.20 ± 0.87 −1.15 ± 1.21 −1.60 ± 1.01 0.002*
3rd order aberration (μm). 0.64 ± 0.34 0.63 ± 0.30 0.64 ± 0.44 0.94 ± 0.84 0.169
Vertical trefoil (Z−33; μm) −0.14 ± 0.37 −0.24 ± 0.34 −0.23 ± 0.43 −0.26 ± 0.60 0.691 Vertical Coma (Z−31; μm) 0.48 ± 3.84 0.01 ± 0.37 0.18 ± 0.42 0.22 ± 0.30 0.947 Horizontal coma (Z13; μm) −0.04 ± 0.33 −0.11 ± 0.32 0.03 ± 0.24 −0.01 ± 0.33 0.632 Oblique trefoil (Z33; μm). −0.01 ± 0.35 −0.04 ± 0.28 −0.02 ± 0.35 −0.19 ± 0.98 0.619
4th order aberration (μm) 0.40 ± 0.30 0.29 ± 0.18 0.38 ± 0.21 0.58 ± 0.45 0.094
Oblique quadrefoil (Z−44; μm) 0.00 ± 0.07 0.04 ± 0.12 −0.00 ± 0.05 0.05 ± 0.14 0.296
Oblique secondary astigmatism 0.01 ± 0.11 0.01 ± 0.13 −0.02 ± 0.11 −0.06 ± 0.17 0.264 Primary spherical (Z04; μm) 0.16 ± 0.30 0.10 ± 0.09 0.20 ± 0.26 0.22 ± 0.54 0.739
Vetical secondary astigmatism 0.08 ± 0.18 0.05 ± 0.16 0.03 ± 0.19 0.06 ± 0.22 0.840
Vertical quadrefoil (Z44; μm) −0.12 ± 0.24 −0.09 ± 0.18 −0.09 ± 0.21 −0.15 ± 0.31 0.903
SimK simulated keratometry, ARK autorefractokeratometry, RMS root mean square, D diopter;
Results were presented as mean ± standard deviation.; *Statistically
Methods
This cross-sectional study was conducted in saveetha medical college and hospitals, Thandalam , Department of Ophthalmology Outpatient department. A total of 44 eyes from 33 patients were included in the chalazion group and 70 eyes from 46 patients comprised the control group.
Chalazia were classified according to location and size. An autokeratorefractometer and a dual- Scheimpflug analyzer were utilized to evaluate corneal changes.
Methodology
Decreased vision due to a chalazion of the upper eyelid has been documented in a patient following laser-assisted in situ keratomileusis (LASIK) [9]. Corneal aberration has been found to affect visual function [10, 11]. Chalazion size and location are to be documented as it is necessary for better outcome of ocular surgery. We have included changes in corneal astigmatism that varies according to chalazion size and location.
44 eyes from 33 patients having eyelid chalazion were assigned to chalazion group. Control group comprised 22 contralateral normal eyes of chalazion patients and 48 eyes from 24 patients without a chalazion were randomly selected and matched according to age and sex. Patient medical history including diabetes mellitus and hypertension were obtained and local examination of eyes and eyelids were performed . Control group patients had no prior history of ophthalmic surgery nad were not using topical or systemic medications on examination.
Chalazia were classified according to their site (upper, lower, or both eyelid groups) and location (nasal, middle, temporal, or whole area of eyelid), according to their size; small (≤1/5 of eyelid), medium (2/5–3/5), or large (>4/5).
An autokeratorefractometer was utilized to measure keratometric values (K) including mean K, flat and steep K, astigmatism, and axis. Central corneal thickness (CCT), corneal topographic data and wavefront aberration data were obtained using a dual-Scheimpflug analyzer (Ziemer Group; Port, Switzerland). Simulated K (simK) were obtained from the central 3-mm zone of the corneas including flat and steep K, mean K, astigmatism (difference between steep and flat Ks), and the axis of the steep meridian. Corneal wavefront aberrations were analyzed, including total root mean square (RMS, in microns) ,total high order aberration, second order aberration, oblique astigmatism (Z−2 2 ), defocus (Z0 2), vertical astigmatism (Z2 2), third order aberration, vertical trefoil (Z−3 3 ), vertical coma (Z−1 3 ), horizontal coma (Z1 3), oblique trefoil (Z3 3), fourth order aberration, oblique quadrefoil (Z−4 4 ), secondary oblique astigmatism (Z−2 4 ), primary spherical aberration (Z0 4), vertical secondary astigmatism (Z2 4), and vertical quadrefoil (Z4 4).
Data Analysis
A total 114 eyes from 64 patients were included :
44 eyes in the chalazion group and 70 eyes in the control group .
Mean patient age was 40.0 ± 13.9 years in the chalazion group and 43.4 ± 14.0 years in the control group.
The chalazion group was divided into the various subgroups:
According to site of the chalazion, the upper eyelid (n = 22), lower eyelid (n = 16), and both eyelids (n = 6, 2) according to the location of the chalazion, the nasal eyelid (n = 10), middle eyelid (n = 25), temporal eyelid (n = 4), and whole eyelid (n = 3), and 3) according to the size of
the chalazion, small (n = 14), medium (n = 17), and large (n = 11) . Corneal topographic data for the chalazion and control groups are presented in Fig. 1 and Table 2.
CCT was not different between the two groups. Astigmatism measured by ARK was not different between the chalazion and control groups (p = 0.074; independent t-test). Oblique astigmatism (Z−2 2 ) was greater in the chalazion group compared with the control group (p = 0.013; independent t-test).
Other topographic data were similar between the chalazion and control groups. Astigmatism by simK, steep K by simK, total RMS, second order aberration, Z−2 2 , and Z2 2 were significantly different between these subgroups (p = 0.001, 0.022, 0.002, <0.001, 0.009, and 0.001, respectively; ANOVA).
Astigmatism by simK was greater in the upper eyelid group compared with the control and lower eyelid groups (p = 0.001 and 0.004, respectively). Steep K by simK significantly differed between upper and lower lids (p = 0.011). Total RMS was greater in the upper eyelid group compared with the control and lower eyelid groups (p = 0.004 and 0.003, respectively). Second order aberration was greater in the upper eyelid group compared with the control, lower eyelid, and whole eyelid groups (p = 0.001, <0.001, and 0.019, respectively). The Z−2 2 was greater in the upper eyelid group compared with the control (p = 0.06). The Z2 2 was greater in the upper eyelid group compared with the control and lower eyelid group, and lower in the upper eyelid group compared with whole eyelid group (p = 0.002, 0.008 and, 0.028, respectively). Corneal topographic changes according to chalazion location are presented in Fig. 3 and Table 4.
Astigmatism by ARK, Z−2 2 , Z0 2, and Z−2 were significantly different between groups (p = 0.046, 0.033, 0.003, and 0.015, respectively; ANOVA). Astigmatism by ARK was significantly different between the control and temporal area groups or between middle and temporal area group (p = 0.019 and 0.025). The Z0 2 was greater in the whole area group compared with the control, nasal, middle, and temporal area groups (p = 0.002, 0.021, 0.001, and 0.004, respectively; Tukey post hoc test). There was a significant difference in Z−2 4 between temporal and whole area groups (p = 0.018; Tukey post hoc test). Corneal topographic changes according to chalazion size are presented in Fig. 4 and Table 5. Astigmatism by simK, second order aberration, Z−2 2 , and Z2 2 were greater in the large-sized chalazion group (p = 0.037, 0.036, 0.006, and 0.002, respectively; ANOVA). Astigmatism by simK and second order aberration was greater in the large-sized chalazion group compared with the control (p = 0.049 for both; Tukey post hoc test). There was a significantly greater Z−2 2 in the large-sized chalazion group compared with the control (p = 0.003; Tukey post hoc test). Z2 2 was greater in the large-sized chalazion group compared with the control and small-sized chalazion groups (p = 0.015 and 0.004, respectively; Tukey post hoc test).
Results (Times New Roman, bold, 12)
Obliquei astigmatism was greater in the chalazion group compared with the control group (p <
0.05). Astigmatism by simulated keratometry (simK), steep K by simK, total root mean square, second order aberration, oblique astigmatism, and vertical astigmatism were significantly greater
in the upper eyelid group (p < 0.05). Astigmatism by simK, second order aberration, oblique astigmatism, and vertical astigmatism were significantly greater in the large-sized chalazion group (p < 0.05). Corneal wavefront aberration was the greatest in the upper eyelid chalazion group, whole area group, and large-sized chalazion group (p < 0.05).
Discussions (Times New Roman, bold, 12)
A chalazion is a very common eyelid disorder affecting individuals of all ages, which caused by pluggingof meibomian glands and chronic lipogranulomatous inflammation of the glands[12].
Chalazia have been reported to increase corneal astigmatism and HOAs [7, 8, 13, 14]. In this study, we have evaluated effects of chalazia on the cornea accordin to chalazia site, location, and size using corneal topography and wavefront analysis. This study revelas mechanical effects of chalazia on corneal astigmatism. Corneal topographical and wavefront assessments have been noted in patients having large sized chalazion have been noted. These changes might be due to following mechanisms. Compressive pressure of chalazia in excessive of these levels can induce the corneal astigmatism. Cornea under reduced strain by corneal refractive surgery (such as LASIK) may be more affected by lower pressure [9]. Lamellar orientation in human corneas has been related to mechanical properties [16, 17]. The mechanical effects increase in the meridian direction as they become closer to the center of the cornea [17]. The pressure-induced meridional strains were smallest at the corneal paracenter and periphery, with the largest recorded at the limbus [18].
The circumferential strains varied less between regions with the para-centre straining to the greatest extent. In the meridional direction, Young’s modulus of elasticity was greatest at the central and para-central corneal regions, while the greatest circumferential elastic modulus was found at the limbus [17, 18]. The para-central region of the human cornea was found to be stiffer in the meridional direction compared with the circumferential direction, suggesting a meridionally-orientated reinforcement of the para-central parts of the human cornea [18]. The human corneal stroma exhibit a preferred collagen orientation in the inferior-superior and nasaltemporal directions. At the limbus, the preferred orientation is tangential to the cornea [19].
Therefore, it is difficult for the pressure on the sclera to have an effect on the cornea in the meridian direction. Chalazia in the middle eyelid can induce corneal astigmatism easily in the meridian direction because it is located superior to the cornea and close to the center of the cornea. Chalazia generally affected Z−2 , an aberration of off-axis rays. HOAs influence sensitivity to contrast to varying degrees at different orientations [20]. These findings may have implications in pediatric patients at risk of amblyopia [13]. Transient chalazion-induced astigmatism can disturb the visual acuity, mislead intraocular lens calculation before cataract surgery, and result in serious error during refractive surgery. Therefore, in these cases, chalazia should be treated in the early phase. Chalazia on long term may induce the remodeling of corneal stroma through the secretion of inflammatory mediators including matrix metalloproteinases.
Chalazia excision can decrease corneal astigmatism and irregularity which is more prominent in single, firm, and central upper eyelid lesions [14]. Treatment modality includes incision and
curettage, intralesional triamcinolone injection, and intralesional botulinum injection.
CONCLUSION
Large-sized chalazia in the upper eyelid should be treated in the early phase because they induce great changes in corneal topography. Before corneal topography is performed Chalazion should be treated preoperatively .
Limitations
This study has its own limitations. In Patients with preexisting astigmatism it is difficult to differentiate whether the chalazion has induced astigmatism or not and their treatment eventually differs.
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