To determine the choroidal thickness in the macular area in patients with idiopathic macular hole in one eye and an unaffected fellow eye and in healthy controls.
Cross-sectional, prospective study.
Twenty-two patients with a full-thickness unilateral idiopathic macular hole and 22 age- and sex-matched controls were recruited. Enhanced depth imaging optical coherence tomography images were obtained by using spectral-domain optical coherence tomography. The choroidal thickness was measured in the subfoveal area and 1000 μm and 2000 μm away from the fovea in the nasal and temporal regions. The diameter of the macular hole and the axial length were determined.
Choroidal thickness was significantly different across the 3 groups at all locations ( P < .001, analysis of variance). The choroid was significantly thinner in eyes with idiopathic macular hole and in unaffected fellow eyes than in the control group ( P < .01, Tukey-Kramer test). The mean subfoveal choroidal thickness was 183.2 μm in the idiopathic macular hole group, 196.6 μm in the fellow-eye group, and 245.0 μm in the control group. A negative correlation between subfoveal choroidal thickness and axial length was found in all groups (macular hole, r = −0.53, P = .01; fellow eyes, r = −0.56, P < .01; controls, r = −0.52, P = .01); in control eyes, a negative correlation was found between choroidal thickness and age ( r = −0.48, P = .02).
Choroidal thickness was reduced in eyes with idiopathic macular hole and also in fellow unaffected eyes. This may suggest a contributing role of the choroid in the pathogenesis of idiopathic macular hole.
Idiopathic macular hole (MH) is a full-thickness defect of retinal tissue involving the anatomic fovea and affecting central visual acuity. The incidence of idiopathic MH was found to be 8.69 eyes per 100 000 population per year, with peak incidence occurring at approximately age 65 years. Although it is generally accepted that idiopathic MH is caused by vitreofoveal traction, other factors may be involved in its pathogenesis, including degenerative macular thinning, degeneration of macular cyst, intrinsic pigment epithelium disease, hormonal influences, and systemic vascular disorders. Also, local vascular alteration may have a role because of the decrease of choroidal blood flow with age, with reduction in density and diameter of the choriocapillaris.
Until now, in vivo measurements of the choroid have used echography, but with limited axial and (even more) lateral resolution, and with difficulty in knowing the exact position from which ultrasound of the posterior segment is obtained. Recently, Spaide and associates, by using spectral-domain optical coherence tomography (OCT), developed a method labeled enhanced depth imaging OCT that enables in vivo cross-sectional imaging of the choroid, so the thickness of the choroid can be measured. Spaide found that the thickness of the central choroid is negatively correlated with age and refractive error. The aim of this study was to determine the choroidal thickness in the macular area in eyes with idiopathic MH compared with unaffected fellow eyes and the eyes of healthy controls and to determine the correlation with patient age, axial length, and hole diameter.
A cross-sectional prospective study was performed at the Department of Ophthalmology of the University of Catania between November 2008 and October 2009. Consecutive patients examined at our retinal outpatient department with a full-thickness (stage 2, 3, or 4) idiopathic MH in one eye and an unaffected fellow eye were recruited. The staging of the MH was according to the Gass classification and was confirmed by OCT. For each patient with MH, each consecutive healthy subject with the same age and sex who fulfilled the inclusion and exclusion criteria was enrolled from our general outpatient department and served as a control; in the control group, 1 eye, randomly selected at the beginning of the study, was examined. The study followed the tenets of the Declaration of Helsinki; all subjects gave their informed consent after the aim and the possible risks of the study had been explained fully.
Exclusion criteria for all groups were: axial length more than 26.00 mm, amblyopia, glaucoma, previous uveitis, ocular trauma or tumor, tapetoretinal dystrophy, angioid streaks, previous central serous chorioretinopathy, choroidal neovascularization, geographic atrophy, drusen of more than 125 μm, confluent drusen, diabetic retinopathy, retinovascular abnormalities, proliferative retinopathy of any type, media opacities that could significantly interfere with OCT imaging, previous refractive surgery or any previous retinal laser or retinal surgery, use of systemic corticosteroids or any intravitreal medications, uncontrolled diabetes or hypertension, and presence of a not clearly detectable limit of the choroid at the measurement of choroidal thickness.
Measurement of choroidal thickness was performed by using the Heidelberg Spectralis (Heidelberg Engineering, Heidelberg, Germany), according to the enhanced depth imaging OCT technique described by Spaide. The camera was positioned close enough to the eye to obtain an inverted image of the choroid. This image was averaged over 100 scans with the automatic averaging and eye tracking features. Seven sections, each comprising 100 averaged scans, were obtained in a 5 × 15-degree rectangle encompassing the macula, and the horizontal section going directly through the center of the fovea was selected. In eyes with idiopathic MH, the horizontal scan passing through the center of the hole was chosen. The resulting images were viewed and measured with the supplied Heidelberg Eye Explorer software (version 184.108.40.206; Heidelberg Engineering). The choroid was measured from the outer portion of the hyperreflective line corresponding to the retinal pigment epithelium to the inner surface of the sclera. These measurements were made at the subfoveal choroid and at 1000 μm and 2000 μm, nasally and temporally, from the center of the fovea. Each image was measured by 2 independent observers (M.Z., A.L.) with discrepancies of more than 15% being resolved by open adjudication with the senior author (M.R.). Measurements of the minimum MH diameter were performed manually by Stratus OCT (Carl Zeiss Meditec, Inc, Dublin, California, USA) using the caliper function at the minimum width of the neurosensory retinal defect. The axial length was measured by A-scan ultrasonography (Cinescan S Quantel Medical, Clermont-Ferrand, France), and the average of 10 consecutive recordings was obtained.
The data obtained were analyzed with frequency and descriptive statistics. The values of the choroidal thickness detected in the 3 groups were compared by analysis of variance. If significant, multiple comparisons were performed by the Tukey-Kramer test. The correlations between subfoveal choroidal thickness and age, axial length, and minimum diameter of the hole were tested by linear regression analysis. A P value less than .05 was considered statistically significant. The statistical analyses used SPSS software version 16.0 (SPSS, Inc, Chicago, Illinois, USA).
The primary outcome measure was the choroidal thickness at 5 locations; the secondary outcome measures were the correlations between subfoveal choroidal thickness and patient age, axial length, and hole diameter.
Of the 30 patients with full-thickness unilateral idiopathic MH, 8 (26.7%) were excluded because they did not meet the eligibility criteria: 1 (3.3%) eye had glaucoma, 2 (6.7%) patients had a history of choroidal neovascularization, 1 (3.3%) patient had undergone previous photodynamic therapy, 1 (3.3%) patient had a history of vitreoretinal surgery, and 1 (3.3%) patient had uncontrolled hypertension; in 2 eyes, the limits of the choroid were not clearly detectable on enhanced depth imaging OCT. Useful scans were obtained from 22 patients (8 male [36.4%]; mean age ± standard deviation [SD], 68 ± 7 years) from the eye affected with idiopathic MH (MH group) and from the unaffected fellow eye (fellow eye group). The control group comprised 22 age- and sex-matched healthy eyes; in 1 subject, measurement was not possible because of poor visualization of the deep border of the choroid, and another subject (of the same age and sex) was included. The baseline demographic and clinical characteristics of the three groups are reported in Table 1 .
|Macular Hole Group (n = 22)||Fellow Eye Group (n = 22)||Control Group (n = 22)||P Value|
|Mean age ± SD (yrs)||68 ± 7||68 ± 7||67 ± 8||NS a|
|Gender (female/male)||14/8||14/8||14/8||NS b|
|Mean ± SD macular hole diameter (μm)||431 ± 276||—||—||—|
|Mean ± SD axial length (mm)||22.8 ± 0.6||22.9 ± 0.8||22.5 ± 0.9||NS a|
As shown in Table 2 , significant differences in choroidal thickness among the 3 groups were seen at all locations ( P < .001, analysis of variance). Compared with the control group, at each location the choroidal thickness was significantly thinner in the idiopathic MH and fellow eye groups ( P < .01, Tukey-Kramer test), with no significant difference between them ( P = not significant, Tukey-Kramer test). The mean ± SD subfoveal choroidal thickness was 183.2 ± 42.1 μm in the idiopathic MH group, 196.6 ± 39.3 μm in the fellow eye group, and 245.0 ± 52.7 μm in the control group ( Figure 1 ). Figure 2 shows enhanced depth imaging OCT images of the choroid of one eye with a MH, the unaffected fellow eye, and a control healthy eye. Table 3 reports values of age, axial length, and subfoveal choroidal thickness of all patients in the MH, fellow eye, and control groups.
|Location (mm)||Macular Hole Group (n = 22)||Fellow Eye Group (n = 22)||Control Group (n = 22)||P Value a|
|Nasal 2 mm ± SD||118 ± 44||126 ± 45||176 ± 56||<0.001|
|Nasal 1 mm ± SD||154 ± 42||166 ± 44||221 ± 61||<0.001|
|Fovea ± SD||183 ± 42||197 ± 39||245 ± 53||<0.001|
|Temporal 1 mm ± SD||183 ± 39||194 ± 36||238 ± 48||<0.001|
|Temporal 2 mm ± SD||166 ± 42||174 ± 42||223 ± 40||<0.001|
|P value (Tukey-Kramer)||NS b||<0.01 c||<0.01 d||—|
|Patient No.||Macular Hole Group||Fellow Eye Group||Control Group|
|Age (years)||Axial Length (mm)||Subfoveal Choroidal Thickness (μm)||Age (years)||Axial Length (mm)||Subfoveal Choroidal Thickness (μm)||Age (years)||Axial Length (mm)||Subfoveal Choroidal Thickness (μm)|