The document summarizes a study that used spectral domain optical coherence tomography (SD-OCT) to measure retinal thickness in the macular region of eyes with different degrees of myopia. The study found that as the degree of myopia and axial length increased, average foveal thickness increased while inner and outer macular thickness decreased. It also found that females had thicker average foveal thickness but thinner overall macular thickness compared to males. The study provides quantitative data on changes in macular thickness correlated with myopia severity, which can help define clinical features of high myopia and develop reliable follow-up methods.

1. RETINAL THICKNESS IN MACULAR
REGION OF HIGH MYOPIC EYES
USING SD-OCT
PRESENTING AUTHOR:
DR. RIDHIKA JHUNJHUNWALA (P.G. RESIDENT)
CO-AUTHOR:
1) DR. SNEHAL BHALSING (ASST. PROF.)
2) DR. ROOPA NAIK (HOD OPHTHALMOLGY)

2. INTRODUCTION
• Myopia or shortsightedness is a type of refractive error in which parallel rays of
light coming from infinity are focused in front of the retina when accommodation is
at rest. Myopia is the most common eye disorder and the complications of high
myopia are contributing factors to blindness1. In high myopia patients (generally
greater than −6.00 diopters, scleral ectasias are relatively frequent and involve the
posterior pole of the eye, leading to poor visual prognosis in adult life 2. The risks
of retinal detachment, chorioretinal atrophy, pigmentary degeneration, and posterior
staphyloma also increase with severity of myopia and increase in axial length3.
• Optical coherence tomography (OCT) is a noninvasive, cross-sectional imaging
technique that can measure macular thickness and is highly reproducible4
. This
technology allows in vivo measurement of retinal thickness and can provided more
accurate scanning, and much higher repeatability and make the detection of subtle
changes in the retina of patients with myopia earlier5.
• In the present study, the retinal thickness in the macular region of myopic patients
was measured using spectral domain OCT under free living conditions, and
analyzed differences among different diopter degrees and influences coming from
axial length, refractive error and gender. The purpose of this study was to provide
basis for defining the clinical features of high myopia and to find reliable
following-up methods for high myopia.

3. AIM
To investigate the changes of retinal thickness in macula of high myopic eyes
using SD-OCT.
MATERIAL AND METHODS
• A total of 82 eyes of 82 subjects (43 males and 39 females) were enrolled.
Thirteen patients were excluded because the OCT detection signal intensity
was <6. Patients were divided into three groups according to their refractive
error/axial length: Low myopia group (LMG) below 2D, Moderate myopia
group (MMG) between 2 to 6D and High myopia group (HMG) above 6D.
• SD-OCT was used to evaluate total average macular thickness, central
subfield thickness, inner/outer macular thickness. Associations between
macular thickness and refractive error/axial length were analyzed by Pearson
correlation analysis.

4. INCLUSION CRITERIA
Patients of middle- aged and young age group of either sex presenting with
refractive error and BCVA above 6/12 was included in this study.
EXCLUSION CRITERIA
Patients with glaucoma, media opacity, uveitis, retinal diseases or histories of
intraocular surgery, refractive surgery, neurologic diseases, and diabetes.

5. RESULT
• There was no significant difference in age among the three groups
(P=0.2789). The central subfield thickness increased with increase in
myopia. The total average macular thickness, inner/outer macular thickness,
decreased with increased myopia/axial length.
• Average foveal thickness had negative correlations with refractive error
(P<0.001), and positive correlations with axial length.
• The inferior and temporal inner macular thickness, all the quadrants of outer
ring, total average macular thickness featured positive correlations with
refractive error, and negative correlations with axial length.
• Average foveal thickness, superior and temporal inner macular thicknesses,
and temporal outer macular thickness was lower in females compared to
males.

6. • OCT image and topographical map of
macular thickness.
• The diameter of three rings are
respectively 1, 3 and 6mm. CST stands
for central subfield thickness, SIM, IIM,
NIM, TIM stand for superior of inner
ring, inferior of inner ring, nasal of
inner ring, and temporal of inner ring,
respectively. SOM, IOM, NOM, TOM
stand for superior of outer ring,
inferior of outer ring, nasal of outer
ring, and temporal of outer ring,
respectively.

7. Baseline data of three diagnostic groups
Group 1 Group 2 Group 3 P
Sample
numbers
26 34 22
Spherical
equivalent
diopter (D)
-1.49±1.38 -5.53±1.95 -9.88±1.76
1
<0.001
Axial length
(mm)
24.39±0.75 26.73±0.97 29.98±1.08
2
<0.001
Gender (M/F) 16/10 18/16 9/13
2
0.36
Age (a) 26.62±5.38 24.33±5.70 25.82±5.68 0.2789
Intraocular
pressure
(mmHg)
13.5±2.2 14.1±2.5 14.0±2.2 0.5928
1One-factor analysis of variance; 2Chi-square test.

8. Macular measurements (µm) in three diagnostic groups
Group 1 (n=26) Group 2 (n=34) Group 3 (n=22)
2
P
CST (µm) 244.56±12.19 254.33±11.61 261.75±11.83 <0.001
SIM (µm) 319.43±16.32 314.41±16.14 314.16±16.08 0.4148
IIM (µm) 315.56±15.84 308.37±12.24 301.25±12.09 0.0019
NIM (µm) 321.81±13.56 317.87±11.07 312.58±16.4 0.0662
TIM (µm) 308.93±14.65 299.62±10.29 296.91±11.49 0.0018
Average thickness
of inner ring (µm)
321.83±10.98 315.35±9.85 313.98±11.45 0.0229
SOM (µm) 283.68±13.26 271.54±8.11 258.00±9.1 <0.001
IOM (µm) 272.15±11.64 255.91±8.61 240.66±7.78 <0.001
NOM (µm) 306.75±11.29 295.37±6.49 285.25±7.94 <0.001
TOM (µm) 264.75±13.41 252.66±9.66 241.33±12.57 <0.001
Average thickness
of outer ring (µm)
281.13±10.92 269.75±11.8 245.25±11.77 <0.001
Total macular
thickness (µm)
280.71±12.41 265.33±11.87 260.74±10.11 <0.001

9. Correlations between macular measurements and
refractive errors and axial length
REFREACTIVE ERROR AXIAL LENGTH
r P r P
CST (µm) -0.318 <0.001 0.391 <0.001
SIM (µm) 0.118 0.165 -0.046 0.604
NIM (µm) 0.034 0.713 -0.038 0.64
IIM (µm) 0.151 0.044 -0.154 0.04
TIM (µm) 0.177 0.018 -0.151 0.044
Average thickness of inner
ring (µm)
0.183 0.03 -0.172 0.02
SOM (µm) 0.403 <0.001 -0.381 <0.001
NOM (µm) 0.245 0.003 -0.272 <0.001
IOM (µm) 0.475 <0.001 -0.497 <0.001
TOM (µm) 0.546 <0.001 -0.541 <0.001
Average thickness of outer
ring (µm)
0.483 <0.001 -0.483 <0.001
Total macular thickness(µm) 0.316 <0.001 -0.151 0.044

10. Gender differences in macular thickness measurement
1
M
1
F
a
P
Cases 43 39
Ages (a) 25.01±5.73 27.13±5.69 0.5180
Diopter (D) -5.46±4.38 -4.85±4.96 0.556
Axial length(mm) 25.56±1.73 26.03±2.01 0.258
Average thickness of inner ring (µm) 317.33±16.33 308.10±17.12 0.0145
Average thickness of outer ring (µm) 273.86±13.12 270.92±14.91 0.3451
Total macular thickness(µm) 274.16±13.17 273.92±14.59 0.9378

11. CONCLUSION
• With an increase in myopia degree/axial length, the
average foveal thickness increased and the inner/outer
macular thickness decreased.
• Females featured thicker average foveal thickness,
and thinner macular thickness compared to males.

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