To describe the features of posterior staphylomas in myopic eyes with an axial length shorter than 26.5 mm causing visual loss in old age.
Retrospective, observational case series.
After reviewing cases of staphyloma, we isolated 16 eyes from 10 patients with an axial length <26.5 mm for further analysis. These patients had all undergone fundus photography and spectral-domain optical coherence tomography (SDOCT) and some had undergone 3-dimensional magnetic resonance imaging (3D-MRI).
The mean age of the patients was 70.0 ± 6.3 years (mean ± standard deviation; range 59–81). The mean axial length of the eyes with a posterior staphyloma was 25.14 ± 0.77 mm and the mean refractive error of the affected eyes was −4.28 ± 2.65 diopters. The median visual acuity was 20/60. All eyes presented with diffuse chorioretinal atrophy, which resembles pathologic myopic maculopathy. Fuchs spots previously were detected in 3 eyes (19%) and lacquer cracks in 2 (12%). SDOCT imaging of the macula showed decreased choroidal thickness in all eyes. A macular retinoschisis was detected in 5 eyes (31%), decreased ellipsoid zone reflectivity in 4 (25%), foveal retinal detachment in 2 (12%), a dome-shaped macula in 1 (6%), a choroidal neovascularization–related subretinal scar in 3 (19%), and loss of ellipsoid zone and outer nuclear layer in 3 (19%). The 3D-MRI scans from 8 eyes showed posterior staphylomas, lateral angulation, or protrusion in all eyes. No eye featured a tilted disc syndrome.
Posterior staphylomas in myopic eyes with an axial length shorter than 26.5 mm exhibit features resembling pathologic myopic maculopathy. This type of staphyloma might cause visual impairment in elderly patients and can be considered atypical forms of pathologic myopia in old age.
In 1801, Antonio Scarpa, a skilled anatomist, first used the term “staphyloma” to describe 2 eyes from a cadaver in which the posterior portion of each eye had pronounced outward bulges. Another posterior scleral protrusion, described by von Ammon in 1832, was postulated to be a congenital condition arising from incomplete closure of the fetal eye cleft. In 1856, Arlt’s anatomic studies established a connection between a posterior staphyloma and myopic refraction. Schnabel reviewed published data and his own cases, which included 34 highly myopic eyes with a refractive error of greater than 8 diopters (D) and 18 myopic eyes not exceeding 8 D. In the group of highly myopic eyes, there was only 1 without a posterior staphyloma, while no staphylomas were found in the second group. In addition, the prevalence of a staphyloma was found by Curtin and Karlin to increase from 1.4% in eyes with an axial length (AL) of 26.5–27.4 mm to 71.4% in eyes measuring 33.5–36.6 mm. Therefore, the presence of a posterior staphyloma and a high degree of myopia (worse refractive error or excessive AL) were thought to be synonymous.
Pathologic myopia is one of the leading causes of blindness worldwide, especially in East Asia because of its high prevalence. The commonly used criteria include a spherical equivalent (SE) of at least −8 D or an AL >26.5 mm. The clinical features of pathologic myopic maculopathy have been well characterized. These include myopic choroidal neovascularization (CNV), macular retinoschisis, macular holes with retinal detachment, lacquer cracks, and diffuse or patchy chorioretinal atrophy. However, the definition of pathologic myopia has not been standardized, although some studies showed that choroidal thickness is a better indicator than AL and SE. In clinical practice, one can encounter some nonpathologic myopic eyes presenting with features of pathologic myopic maculopathy, such as CNV, diffuse chorioretinal atrophy, staphylomas, or macula retinoschisis. Whether these eyes belong to another disease category related to aging processes or an atypical form of pathologic myopia is unknown.
In this study, 16 eyes from 10 patients with posterior staphylomas resembling pathologic myopic maculopathy, but without an AL >26.5 mm, are described. The most striking feature was the decreased choroidal thickness in these patients with a mean age of 70.0 ± 6.3 years and irregular oval-shaped type 1 staphylomas with extensions temporally and inferiorly. Lateral angulations and protrusions were found using 3-dimensional magnetic resonance imaging (3D-MRI) analysis. In addition, the SE values of all these eyes were not greater than 8 D. A retrospective analysis of clinical data, fundus photography, spectral-domain optical coherence tomography (SDOCT), and 3D-MRI is presented for these 16 eyes.
The medical records of patients with posterior staphylomas were reviewed retrospectively. This retrospective study was approved by the Institutional Review Board of Chang Gung Memorial Hospital, Taiwan (103–2767B) in 2014. The procedures used conformed to the tenets of the Declaration of Helsinki. All patients were examined between July 1, 2012 and June 16, 2014. The diagnosis of a posterior staphyloma using stereoscopic fundus photography was decided by agreement between 2 of the authors (N.K.W. and C.C.L.). Highly myopic eyes with an AL >26.5 mm were excluded. This arbitrary cutoff for AL was chosen for the purpose of this study to isolate a pure form of posterior staphyloma not qualified for the definition of pathologic myopia (SE of at least −8 D or an AL >26.5 mm).
All patients had undergone a comprehensive ophthalmologic examination, including a slit-lamp examination, indirect ophthalmoscopy, measurement of best-corrected visual acuity, evaluation of their spherical equivalent refractive error (measured using a KR-8100 Autorefractor; Topcon, Tokyo, Japan), and biometry (measured using an IOLMaster; Carl Zeiss, Jena, Germany). The IOLMaster measurement of AL has several advantages over ultrasonography, such as providing a true cornea-to-macula distance with patient fixation, avoiding interference from epiretinal membranes or foveoschisis because the measurement is done to the level of the retinal pigment epithelium. Stereoscopic fundus photography was done using a fundus camera (TRC-50EX; Topcon, or Nonmyd α-DIII; KOWA, Tokyo, Japan) after pupil dilation. Maculopathy was classified using international photographic classification and a grading system for myopic maculopathy.
All the eyes had been examined by SDOCT using a Spectralis HRA-OCT system (Heidelberg Engineering, Dossenheim, Germany). Some eyes were examined using multimodal confocal scanning laser ophthalmoscopy (cSLO) imaging including fundus autofluorescence (FAF), a fluorescence angiogram (FA), and indocyanine green angiogram imaging using a cSLO (Heidelberg Retina Angiograph HRA2; Heidelberg Engineering) as described previously.
High-resolution 3D-MRI images of the eyes were acquired with a 3-Tesla MRI scanner (Discovery MR750; GE Healthcare, Waukesha, Wisconsin, USA), using a T 2 -weighted coronal 3D-FSE-Cube pulse sequence with fat saturation and the following parameters: TR/effective TE = 2500/80 ms, echo train length = 100, FOV = 20 × 20 cm, matrix = 320 × 320, partition number = 80, thickness per partition = 1 mm, voxel size = 0.626 × 0.625 × 0.5 mm (interposition in the z-axis), NEX = 1, Arc = 2, and acquisition time = 2 minutes 23 seconds. Subjects were instructed to relax with their eyes closed during scans. The acquired volume data were processed on a GE AW VolumeShare 4 workstation (GE Healthcare). The configuration of the eyeball was demonstrated using a volume-rendering technique, and ALs were measured on multiplanar reformatted images.
Sixteen eyes of 10 patients (7 women and 3 men) were included in this study. Among these patients, 6 had bilateral and the other 4 had unilateral posterior staphylomas. The mean age of the patients was 70.0 ± 6.3 years (mean ± standard deviation; range 59–81). All patients presented with progressive visual loss. The mean AL of the eyes with a posterior staphyloma was 25.14 ± 0.77 mm with a range of 23.65–26.28 mm, and the mean refractive error (spherical equivalents) was −4.28 ± 2.65 D with a range of −0.88 to −9.88 D. The refractive errors of both eyes (right eye −9.88 D; left eye −9.62 D) of Patient 4 were overestimated because of nuclear sclerosis type cataracts; the patient reported that her myopia had been −4 D several years before she came to our clinic. The mean radius of corneal curvature was 7.49 ± 0.16 mm with a range of 7.16–7.75 mm, and the mean anterior chamber depth (ACD) was 3.14 ± 0.30 mm with a range of 2.50–3.50 mm. The clinical characteristics of the patients are shown in the Table .
|Patient/Sex||Age, y||Eye||SE (D)||BCVA||CC, mm||ACD, mm||AL, mm||Fundus||SDOCT||MRI a /B Scan b||Type of Staphyloma|
|1/F||67||OD||−4.00||20/60||7.73||3.41||26.1||Diffuse chorioretinal atrophy||Thin choroid, decreased EZ reflectivity||Staphyloma a||Type 1|
|2/F||78||OD||−0.88||CF/60 cm||7.75||3.44||24.95||Diffuse chorioretinal atrophy||Thin choroid, subfoveal EZ loss, retinoschisis||Staphyloma a||Type 1|
|78||OS||−2.38||20/60||7.65||3.47||25.15||Diffuse chorioretinal atrophy||Thin choroid, decreased EZ reflectivity||Staphyloma a||Type 1|
|3/F||75||OD||−1.75||20/60||7.16||2.5||23.65||Diffuse chorioretinal atrophy||Thin choroid, decreased EZ reflectivity||Staphyloma a||Type 1|
|4/F||70||OD||−9.88 c||20/1000||7.39||2.67||25.92||Atrophic lesion around neovascular membrane, Fuchs spot||Thin choroid, subretinal scar||Staphyloma a||Type 1|
|70||OS||−9.62 c||CF/80 cm||7.45||2.75||26.2||Atrophic lesion around neovascular membrane, Fuchs spot||Thin choroid, foveal atrophy||Staphyloma a||Type 1|
|5/M||67||OD||−2.13||20/100||7.58||3.1||24.47||Atrophic lesion around neovascular membrane, Fuchs spot||Thin choroid, subretinal scar||N/A||Type 1|
|67||OS||−2.25||20/40||7.61||3.52||25.64||Diffuse chorioretinal atrophy||Thin choroid||N/A||Type 1|
|6/M||73||OD||−3.5||20/60||7.53||3.01||25.34||Diffuse chorioretinal atrophy||Retinoschisis and detachment||Staphyloma b||Type 1|
|73||OS||−2.13||20/60||7.56||3.14||24.67||Diffuse chorioretinal atrophy||Retinoschisis, macula hole and detachment||Staphyloma b||Type 1|
|7/F||68||OD||−5.75||20/30||7.26||3.41||24.52||Diffuse chorioretinal atrophy||Thin choroid||N/A||Type 1|
|68||OS||−7.00||20/60||7.28||3.27||24.99||Diffuse chorioretinal atrophy, lacquer cracks||Thin choroid, retinoschisis||N/A||Type 1|
|8/F||59||OD||−2.00||20/100||7.5||3.14||23.77||Diffuse chorioretinal atrophy||Retinoschisis||Staphyloma a||Type 1|
|59||OS||−5.75||20/30||7.49||3.14||25.27||Diffuse chorioretinal atrophy, intrachoroidal cavitation||Intrachoroidal cavitation||Staphyloma a||Type 1|
|9/F||81||OD||−4.75||20/100||7.49||3.14||25.32||Diffuse chorioretinal atrophy, lacquer cracks||Thin choroid, foveal atrophy, dome−shaped macula, EZ loss||Staphyloma a||Type 1|
|10/M||62||OD||−4.63||20/600||7.42||N/A||26.28||Diffuse chorioretinal atrophy||Thin choroid, decreased EZ reflectivity||N/A||Type 1|